Ground fissure,as a common geo-hazard,impairs the integrity of the site soil and affects the seismic performance of engineering structures.In this paper,a finite element(FE)model for subway stations in a ground fissur...Ground fissure,as a common geo-hazard,impairs the integrity of the site soil and affects the seismic performance of engineering structures.In this paper,a finite element(FE)model for subway stations in a ground fissure area was developed and validated by using experimental results.Numerical analyses were conducted to investigate the seismic response and failure mode of subway stations in a ground fissure area with different locations.Effects of ground fissure on deformations and internal forces of a station,soil pressures and soil plastic strains were discussed.The results showed that the seismic response of the station was significantly amplified by the ground fissure,and stations in the ground fissure area displayed obvious rocking deformation during earthquakes as compared to those in the area without fissures.It also was found that the soil yielding around the station,the dislocation occurring in the ground fissure area,and the dynamic amplification effect were more significant under vertical ground motion,which weakened the station’s ductility and accelerated its destruction process.展开更多
Since the 1950's,212 earth fissures have been discovered in the Wei River Basin.During a field survey in 2016,an additional 48 earth fissures were discovered in Anren area,northeast of the Wei River Basin.The char...Since the 1950's,212 earth fissures have been discovered in the Wei River Basin.During a field survey in 2016,an additional 48 earth fissures were discovered in Anren area,northeast of the Wei River Basin.The characteristics and formation mechanisms of these fissures were studied through field investigations,measurements,trench excavation,and drilling.On-site investigations indicated that these earth fissures were distributed along a fault-controlled geomorphic boundary.Fissures trended at 60°-80°NE and were divided into five groups.Trenches revealed multiple secondary fissures,exposing severe soil ruptures in the shallow earth surfaces.Drilling profiles revealed that earth fissures dislocated several strata,and resembled synsedimentary faults.Seismic reflection profiles revealed buried faults beneath the earth fissures.The Anren area fissures formed in the following three stages:regional extension that initially generated multiple buried faults;seismic activity rupturing multiple strata,resulting in multiple buried fractures;and finally,erosion processes that propagated the buried fractures to the surface,forming the current earth fissures.展开更多
The recent upsurge in metro construction emphasizes the necessity of understanding the mechanical performance of metro shield tunnel subjected to the influence of ground fissures.In this study,a largescale experiment,...The recent upsurge in metro construction emphasizes the necessity of understanding the mechanical performance of metro shield tunnel subjected to the influence of ground fissures.In this study,a largescale experiment,in combination with numerical simulation,was conducted to investigate the influence of ground fissures on a metro shield tunnel.The results indicate that the lining contact pressure at the vault increases in the hanging wall while decreases in the footwall,resulting in a two-dimensional stress state of vertical shear and axial tension-compression,and simultaneous vertical dislocation and axial tilt for the segments around the ground fissure.In addition,the damage to curved bolts includes tensile yield,flexural yield,and shear twist,leading to obvious concrete lining damage,particularly at the vault,arch bottom,and hance,indicating that the joints in these positions are weak areas.The shield tunnel orthogonal to the ground fissure ultimately experiences shear failure,suggesting that the maximum actual dislocation of ground fissure that the structure can withstand is approximately 20 cm,and five segment rings in the hanging wall and six segment rings in the footwall also need to be reinforced.This study could provide a reference for metro design in ground fissure sites.展开更多
Granite residual soil slope is often destroyed,which poses great threats to Rong County in southeastern Guangxi,China.Heavy rainfall and fissures are the major triggering and internal factors.The fissure that controls...Granite residual soil slope is often destroyed,which poses great threats to Rong County in southeastern Guangxi,China.Heavy rainfall and fissures are the major triggering and internal factors.The fissure that controls the slope stability and the associated failure mechanisms remain unclear.The purpose of this study was to identify the controlling fissures through field investigation,elucidate the effect of its position,and analyze the failure process and hydrological response of residual soil slope through artificial flume model tests.The results comprised five aspects.(1)Surface weathering and unloading fissures could affect slope stability.(2)The failure processes with different fissure positions exhibited inconsistent characteristics.(3)The volume moisture content(VMC)had the most direct response at the fissure tip.The corresponding infiltration rate was the highest.The response time of pore water pressure(PWP)was longer than that of VMC.Fluctuations in PWP were associated with VMC and changes in the soil microstructure due to local deformation.(4)Slope failure was accompanied by serious soil erosion.This could be attributed to the infiltration direction and the interaction between soil and water.(5)Fissured soil slopes experienced five similar failure processes:sheet erosion and partial failure of the slope foot,occurrence of preferential flow and enlargement of the sliding area,creep deformation and tension fissure emergence,block sliding and gully erosion,and flow-slip.展开更多
Fissured clays exhibit unique geotechnical behaviors,with the stiffness characteristics evolving dynamically in response to environmental changes.To address this issue,reported here is a systematic assessment of how d...Fissured clays exhibit unique geotechnical behaviors,with the stiffness characteristics evolving dynamically in response to environmental changes.To address this issue,reported here is a systematic assessment of how dryingewetting(DW)cycles affect the small-strain stiffness characteristics of fissured clay.Resonant column tests are taken to examine the nonlinear attenuation behavior of the small-strain shear modulus(SSSM)and damping ratio of fissured clay under various DW cycle and consolidation pressure(25e200 kPa)conditions.Scanning electron microscopy(SEM)and computed tomography(CT)are employed to reveal the microstructure of fissured clay.The HardineDrnevich(H-D)model is used to describe the decay law of its SSSM,and the small strain stiffness characteristics of fissured soil are analyzed in view of damage mechanics.The results show that the SSSM of the fissured clay decreases as the DWcycles increase,with the greatest attenuation at original soil state.The damping ratio exhibits an incremental trend with escalating strain and a higher number of DW cycles.Regarding damage,DW cycles can lead to the formation of microcracks in the sample,and the aggregates disperse into smaller aggregates,which then aggregates again,resulting in structural damage.The damage variables of the samples under various confining pressures and DW cycles are analyzed based on the principle of strain damage.Finally,the volume changes and the distribution of different pore sizes obtained through CT are analyzed to investigate the stiffness attenuation under DW cycles.Additionally,the study examines the propagation direction of secondary cracks induced by primary fissures,which will play an important role in reduction of the stiffness.Our investigations contribute to understanding of soil mechanics and practical applications in areas where fissured clay is prevalent.展开更多
Fissured coal mass under triaxial unloading condition exhibits higher burst potential than the triaxial loading condition,which poses challenge to safety and productivity of resources extraction and underground space ...Fissured coal mass under triaxial unloading condition exhibits higher burst potential than the triaxial loading condition,which poses challenge to safety and productivity of resources extraction and underground space utilization.To comprehensively understand the mechanism of unloading-induced burst during excavation process,this study investigated the fracture and energy evolution of samples with different fissure types such as single,two parallel,and two coplanar-parallel using PFC2D modelling.Triaxial loading tests were conducted to determine the compressive strengths and other parameters.With increase of fissure inclination angle,the triaxial compressive strength decreases forβ=0°-30°,and then increase forβ=30°-90°.The strength of samples with two coplanar-parallel fissures is the highest.Fissure can significantly change the distribution of fracture and elastic energy.Secondary cracks were generated starting from both ends of the fissure.Forβ=0°-60°,low elastic strain energy area was produced around the fissure along the loading direction.The elastic strain energy is transferred to the outside of fissures.Forβ=75°-90°,only a small amount of high elastic strain energy was generated on both sides of the fissure.The fracture expansion under unloading conditions occurred due to tensile stress T caused by unloading differential rebound deformation and the shear stress on the fissure surface.展开更多
Taking the Pusa Collapse in Nayong County,Guizhou Province,China as a case study,this paper investigates the impact of multi-layer coal mining on karst mountains characterized by deep fissures.Based on field investiga...Taking the Pusa Collapse in Nayong County,Guizhou Province,China as a case study,this paper investigates the impact of multi-layer coal mining on karst mountains characterized by deep fissures.Based on field investigations and employing discrete element numerical simulations,the deformation and failure mechanisms of karst mountain containing deep and large fissures under multi-seam mining conditions was investigated.The influence of the direction of coal seam extraction and the sequence of extraction between multiple coal seams on the failure modes of karst mountain with deep and large fissures was studied.The results indicate that underground mining primarily manifests in the development of mininginduced fissures in the mountain body,subsidence and deformation of slope masses,and triggering the expansion of existing fissures,further driving overall deformation and damage to the slopes.Deep and large fissures control the deformation and failure modes of the slopes,with closer and longer deep and large fissures near the slope surface exerting greater influence on the slope mass.The impact of mining in the same coal seam direction on the slopes is mainly reflected in the process of slope deformation and failure.Downslope mining directly leads to overall subsidence of the slope mass,squeezing the front and lower parts of the slope mass.Upslope mining initially causes the foot of the slope to sink and the entire slope mass to move outward,and continuous mining leads to overall settlement and downward compression deformation of the slope.The sequence of mining between multiple coal seams mainly affects the overall and local deformation values of the slope mass.Downward mining leads to increased overall subsidence of the slope mass and exacerbates the backward tilt of the slope top.展开更多
To explore the effects of freeze‒thaw cycles on the mechanical properties and crack evolution of fissured sandstone,biaxial compression experiments were carried out on sandstone subjected to freeze‒thaw cycles to char...To explore the effects of freeze‒thaw cycles on the mechanical properties and crack evolution of fissured sandstone,biaxial compression experiments were carried out on sandstone subjected to freeze‒thaw cycles to characterize the changes in the physical and mechanical properties of fissured sandstone caused by freeze‒thaw cycles.The crack evolution and crack change process on the surface of the fissured sandstone were recorded and analysed in detail via digital image technology(DIC).Numerical simulation was used to reveal the expansion process and damage mode of fine-scale cracks under the action of freeze‒thaw cycles,and the simulation results were compared and analysed with the experimental data to verify the reliability of the numerical model.The results show that the mass loss,porosity,peak stress and elastic modulus all increase with increasing number of freeze‒thaw cycles.With an increase in the number of freeze‒thaw cycles,a substantial change in displacement occurs around the prefabricated cracks,and a stress concentration appears at the crack tip.As new cracks continue to sprout at the tips of the prefabricated cracks until the microcracks gradually penetrate into the main cracks,the displacement cloud becomes obviously discontinuous,and the contours of the displacement field in the crack fracture damage area simply intersect with the prefabricated cracks to form an obvious fracture.The damage patterns of the fractured sandstone after freeze‒thaw cycles clearly differ,forming a symmetrical"L"-shaped damage pattern at zero freeze‒thaw cycles,a symmetrical"V"-shaped damage pattern at 10 freeze‒thaw cycles,and a"V"-shaped damage pattern at 20 freeze‒thaw cycles.After 20 freeze‒thaw cycles,a"V"-shaped destruction pattern and"L"-shaped destruction pattern are formed;after 30 freeze‒thaw cycles,an"N"-shaped destruction pattern is formed.This shows that the failure mode of fractured sandstone gradually becomes more complicated with an increasing number of freeze‒thaw cycles.The effects of freeze‒thaw cycles on the direction and rate of crack propagation are revealed through a temperature‒load coupled model,which provides an important reference for an in-depth understanding of the freeze‒thaw failure mechanisms of fractured rock masses.展开更多
BACKGROUND Laparoscopic hepatectomy is a proven safe and technically feasible approach for liver tumor resection,but laparoscopic anatomical SVIII resection(LASVIIIR)remains rarely reported due to poor accessibility,d...BACKGROUND Laparoscopic hepatectomy is a proven safe and technically feasible approach for liver tumor resection,but laparoscopic anatomical SVIII resection(LASVIIIR)remains rarely reported due to poor accessibility,difficult exposure,and the deep-lying Glissonean pedicle.This study examined the safety,feasibility,and perio-perative outcomes of LASVIIIR via a middle hepatic fissure approach at our in-stitution.AIM To investigate the safety,feasibility,and perioperative outcomes of LASVIIIR via a middle hepatic fissure approach at our institution.METHODS From November 2017 to December 2022,all patients with a liver tumor who underwent LASVIIIR were enrolled.The perioperative outcomes and postope-rative complications were evaluated.RESULTS Thirty-four patients underwent LASVIIIR via a middle hepatic fissure approach from the side or cranio side and were included.The mean operation time was 164±54 minutes,and the intra-operative blood loss was 100 mL(range:20-1000 mL).The mean operative times were,respectively,152±50 minutes and 222±29 minutes(P=0.001)for the caudal side and cranial side approaches.In addition,the median blood loss volumes were 100 mL(range:20-300 mL)and 250 mL(range:20-1000 mL),respectively,for the caudal and cranial sides(P=0.064).Three patients treated using the cranial side approach experienced bile leakage,while 1 patient treated using the caudal side approach had subphrenic collection and underwent percutaneous drainage to successfully recover.There were no differences regarding postoperative hospital stays for the caudal and cranial side approaches[9(7-26)days vs 8(8-19)days](P=0.226).CONCLUSION LASVIIIR resection remains a challenging operation,but the middle hepatic fissure approach is a reasonable and easy-to-implement technique.展开更多
In the engineering practices,it is increasingly common to encounter fractured rocks perturbed by temperatures and frequent dynamic loads.In this paper,the dynamic behaviors and fracture characteristics of red sandston...In the engineering practices,it is increasingly common to encounter fractured rocks perturbed by temperatures and frequent dynamic loads.In this paper,the dynamic behaviors and fracture characteristics of red sandstone considering temperatures(25℃,200℃,400℃,600℃,and 800℃)and fissure angles(0°,30°,60°,and 90°)were evaluated under constant-amplitude and low-cycle(CALC)impacts actuated by a modified split Hopkinson pressure bar(SHPB)system.Subsequently,fracture morphology and second-order statistics within the grey-level co-occurrence matrix(GLCM)were examined using scanning electron microscopy(SEM).Meanwhile,the deep analysis and discussion of the mechanical response were conducted through the synchronous thermal analyzer(STA)test,numerical simulations,one-dimensional stress wave theory,and material structure.The multiple regression models between response variables and interactive effects of independent variables were established using the response surface method(RSM).The results demonstrate the fatigue strength and life diminish as temperatures rise and increase with increasing fissure angles,while the strain rate exhibits an inverse behavior.Furthermore,the peak stress intensification and strain rate softening observed during CALC impact exhibit greater prominence at increased fissure angles.The failure is dominated by tensile damage with concise evolution paths and intergranular cracks as well as the compressor-crushed zone which may affect the failure mode after 400℃.The second-order statistics of GLCM in SEM images exhibit a considerable dependence on the temperatures.Also,thermal damage dominated by thermal properties controls the material structure and wave impedance and eventually affects the incident wave intensity.The tensile wave reflected from the fissure surface is the inherent mechanism responsible for the angle effect exhibited by the fatigue strength and life.Ultimately,the peak stress intensification and strain rate softening during impact are determined by both the material structure and compaction governed by thermal damage and tensile wave.展开更多
Nearly 1100 fissures have formed on the Hebei Plain in China.Within the Yellow RiverQinghe River-Zhanghe River shallow buried paleochannel band on the plain,93 ground fissures controlled by paleochannels have develope...Nearly 1100 fissures have formed on the Hebei Plain in China.Within the Yellow RiverQinghe River-Zhanghe River shallow buried paleochannel band on the plain,93 ground fissures controlled by paleochannels have developed,of which the Wuyi-Fuping ground fissure is a typical paleochannel-controlled fissure located in Hengshui,Hebei Province,with a total length of 3 km,a dominant strike of NE78°,and nearly upright in the shallow layer.The surface damage observed in this fissure primarily manifests as beaded pits,and its activity shows distinct segmentation characteristics.On the trench profiles,the offset distance of shallow layers remains consistently around 20 cm within the depth range of 0 to-3 m.An evident flexure is observed in the strata at depths ranging from-4.5 to-7 m.The drilling profile reveals that there is an absence of dislocations in the deeper strata.Nonetheless,the shallow seismic physical profiles unveil the presence of underlying faults beneath the study area,underscoring the intricate formation process and genesis mechanism of the Wuyi-Fuping ground fissure.Firstly,the formation and evolution of the Qingling River's paleochannel were shaped by the actions of fault blocks and underlying faults.The interplay of the regional stress field,fault block movement,and fault activity played pivotal roles in driving the development of this paleochannel.Secondly,the paleochannel exerts a controlling influence on the development location and severity of the fissure.During pumping,the confined aquifer within the paleochannel undergoes water loss and compression,resulting in the formation of a surface subsidence funnel.When the tensile stress surpasses the soil's tensile strength at the funnel's edge,the soil fractures give rise to a ground fissure.Finally,large amounts of surface water generated by heavy rainfall and irrigation can cause existing hidden ground fissures to rupture,emerge,and expand.This paper provides a heretofore generally unknown example,promotes research on the mechanisms of paleochannel-controlled fissures,and has guiding significance for disaster prevention and reduction in this area.展开更多
The Fenwei Basin, covered by loess, experiences severe ground fissure disasters. These disasters disrupt the continuity of the loess and pose significant threats to engineering construction safety along transportation...The Fenwei Basin, covered by loess, experiences severe ground fissure disasters. These disasters disrupt the continuity of the loess and pose significant threats to engineering construction safety along transportation routes. Nevertheless, the crack characteristics and the influence zone of ground fissures in the loess layer remain inadequately investigated. To effectively prevent and control ground fissure disasters, physical model tests and the PFC(particle flow code) numerical simulation method are used to investigate the crack mechanism of buried ground fissures in the loess layer. The results show that there are two main cracks in the layer profile, which have a Y-shape morphology. As the dip angle of the preset cracks increased from 60° to 90°, the main deformation zone at the surface gradually shifted towards the footwall. The process of crack propagation from depth to surface is divided into five stages. Additionally, the results confirm the accuracy of the width of the rupture zone d2in the footwall calculated by the cantilever beam theory. These findings can offer theoretical guidance for determining the avoidance distance of ground fissures in loess regions, as well as for implementing disaster prevention and corresponding control measures for various stages of buried ground fissure propagation.展开更多
The Inner Mongolia mining area in western China are characterized by the development of numerous penetrating fissures,resulting in severe land damage.It is significant to reveal the underlying evolution mechanism and ...The Inner Mongolia mining area in western China are characterized by the development of numerous penetrating fissures,resulting in severe land damage.It is significant to reveal the underlying evolution mechanism and identify treatment timing for restoring the ecological environment.The Guanbanwusu mining subsidence area in Inner Mongolia,China was selected as the research case for this study.The evolution mechanism of different penetrating fissures was revealed by field measurement,physical simulation and theoretical analysis.The treatment timing prediction model for the mining subsidence area was established based on the enhanced Weibull time function.The results show that the ground fissures are mainly step-type and collapse-type fissures.The breaking form of overlying strata determines their vertical opening and horizontal dislocation.The high mining intensity in the western mining area results in a shortened period of dynamic fissure expansion and reduced closure degree.The damage extent of the overlying strata exhibits zoning characteristics both vertically and horizontally.The relative standard deviation of the prediction model is only 3.7%.Concurrently,the prediction model is employed to determine the optimal timing for treatment in the study area,estimated to be 259 days.Subsequently,once this threshold is reached,the study area undergoes treatment and restoration of its e cological environment.This study addresses the knowledge gap in this field by highlighting the interconnectedness between rock strata structure and evolution mechanism of penetrating fissures,thereby providing a method for determining the treatment timing in mining subsidence areas.展开更多
Heat transfer and temperature evolution in overburden fracture and ground fissures are one of the essential topics for the identification of ground fissures via unmanned aerial vehicle(UAV) infrared imager. In this st...Heat transfer and temperature evolution in overburden fracture and ground fissures are one of the essential topics for the identification of ground fissures via unmanned aerial vehicle(UAV) infrared imager. In this study, discrete element software UDEC was employed to investigate the overburden fracture field under different mining conditions. Multiphysics software COMSOL were employed to investigate heat transfer and temperature evolution of overburden fracture and ground fissures under the influence of mining condition, fissure depth, fissure width, and month alternation. The UAV infrared field measurements also provided a calibration for numerical simulation. The results showed that for ground fissures connected to underground goaf(Fissure Ⅰ), the temperature difference increased with larger mining height and shallow buried depth. In addition, Fissure Ⅰ located in the boundary of the goaf have a greater temperature difference and is easier to be identified than fissures located above the mining goaf. For ground fissures having no connection to underground goaf(Fissure Ⅱ), the heat transfer is affected by the internal resistance of the overlying strata fracture when the depth of Fissure Ⅱ is greater than10 m, the temperature of Fissure Ⅱ gradually equals to the ground temperature as the fissures’ depth increases, and the fissures are difficult to be identified. The identification effect is most obvious for fissures larger than 16 cm under the same depth. In spring and summer, UAV infrared identification of mining fissures should be carried out during nighttime. This study provides the basis for the optimal time and season for the UAV infrared identification of different types of mining ground fissures.展开更多
The main objective of this study is to determine the hydrogeochemical specificities of the groundwater of the Angovia mine operating permit, located in the Yaouré mountains in the center-west of Côte d’Ivoi...The main objective of this study is to determine the hydrogeochemical specificities of the groundwater of the Angovia mine operating permit, located in the Yaouré mountains in the center-west of Côte d’Ivoire. To do so, descriptive and multivariate statistical analysis methods with the SOM (Self Organizing Maps) algorithm were applied to the physicochemical parameters of 17 boreholes using the calcite (ISC) and dolomite (ISD) saturation indices. The results obtained have shown that the groundwater in the Angovia mine operating permit area has an average temperature of 27.52°C (long rainy season) and 27.87°C (long dry season) and has an average pH of 7.09 ± 0.35 during the main rainy season and 7.32 ± 0.35 during the main dry season. They are mineralized with an average electrical conductivity of 505.98 ± 302.85 μS/cm during the long rainy season and with 450.33 ± 233.74 μS/cm as average during the long dry season. The main phenomena at the origin of groundwater mineralization are water residence time, oxidation-reduction and surface inflow. The study of the relative age of the water shows that the groundwater in the Angovia mine operating permit area is mainly undersaturated with respect to calcite and dolomite. They are therefore very old in the aquifer with a slow circulation speed during the long rainy season and the long dry season.展开更多
Chronic anal fissure(CAF)is a painful tear or crack which occurs in the anoderm.The optimal algorithm of therapy for CAF is still debated.Lateral internal sphincterotomy(LIS)is a surgical treatment,considered as the&#...Chronic anal fissure(CAF)is a painful tear or crack which occurs in the anoderm.The optimal algorithm of therapy for CAF is still debated.Lateral internal sphincterotomy(LIS)is a surgical treatment,considered as the'gold standard'therapy for CAF.It relieves CAF symptoms with a high rate of healing.Chemical sphincterotomy(CS)with nitrates,calcium blockers or botulinum toxin(BTX)is safe,with the rapid relief of pain,mild sideeffects and no risk of surgery or anesthesia,but is a statistically less effective therapy for CAF than LIS.This article considers if aggressive treatment should only be offered to patients who fail pharmacological sphincterotomy.Aspects of anal fissure etiology,epidemiology and pathophysiology are considered with their meaning for further management of CAF.A molecular model of chemical interdependence significant for the chemistry of CAF healing is examined.Its application may influence the development of optimal therapy for CAF.BTX is currently considered the most effective type of CS and discussion in this article scrutinizes this method specifically.Although the effectiveness of BTXvs LIS has been discussed,the essential focus of the article concerns identifying the best therapy application for anal fissure.Elements are presented which may help us to predict CAF healing.They provide rationale for the expansion of the CAF therapy algorithm.Ethical and economic factors are also considered in brief.As long as the patient is willing to accept the potential risk of fecal incontinence,we have grounds for the'gold standard'(LIS)as the first-line treatment for CAF.The author concludes that,when the diagnosis of the anal fissure is established,CS should be considered for both ethical and economic reasons.He is convinced that a greater understanding and recognition of benign anal disorders by the GP and a proactive involvement at the point of initial diagnosis would facilitate the consideration of CS at an earlier,more practical stage with improved outcomes for the patient.展开更多
BACKGROUND Lateral internal sphincterotomy is still the approach of choice for the treatment of chronic anal fissure(CAF)with internal anal sphincter(IAS)hypertonia,but it is burdened by high-risk postoperative faecal...BACKGROUND Lateral internal sphincterotomy is still the approach of choice for the treatment of chronic anal fissure(CAF)with internal anal sphincter(IAS)hypertonia,but it is burdened by high-risk postoperative faecal incontinence(FI).Sphincter saving procedures have recently been reconsidered as treatments to overcome this risk.The most employed procedure is fissurectomy with anoplasty,eventually associated with pharmacological sphincterotomy.AIM To evaluate whether fissurectomy and anoplasty with botulinum toxin injection improves the results of fissurectomy and anoplasty alone.METHODS We conducted a case-control study involving 30 male patients affected by CAF with hypertonic IAS who underwent fissurectomy and anoplasty with V-Y cutaneous flap advancement.The patients were divided into two groups:Those in group I underwent surgery alone,and those in group II underwent surgery and a botulinum toxin injection directly into the IAS.They were followed up for at least 2 years.The goals were to achieve complete healing of the patient and to assess the FI and recurrence rate along with manometry parameters.RESULTS The intensity and duration of post-defecatory pain decreased significantly in both groups of patients starting with the first defecation,and this reduction was higher in group II.Forty days after surgery,we achieved complete wound healing in all the patients in group II but only in 80%of the patients in group I(P<0.032).We recorded 2 cases of recurrence,one in each group,and both healed with conservative therapy.We recorded one temporary and low-grade postoperative case of“de novo”FI.Manometry parameters reverted to the normal range earlier for group II patients.CONCLUSION The injection of botulinum toxin A in association with fissurectomy and anoplasty with a V-Y advancement flap improves the results of surgery alone in patients affected by CAF with IAS hypertonia.展开更多
One of the most intriguing aspects of the evolution of Mount Etna(eastern Sicily)is the switch from a fissuretype shield volcano coincident with the Ionian coast to an inland cluster of nested stratovolcanoes close to...One of the most intriguing aspects of the evolution of Mount Etna(eastern Sicily)is the switch from a fissuretype shield volcano coincident with the Ionian coast to an inland cluster of nested stratovolcanoes close to the currently active centre.Previous geological studies infer that the switch reflects a tectonically-driven rearrangement of the major border faults that direct the Etnean plumbing system,loosely dated at around 125 ka BP.New offshore structural studies throw this prevailing view into question,whilst a revised chronological framework indicates that the transformation from fissure-to central-type activity was abrupt,effectively occurring 129–126 ka BP.In recognising that this period corresponds closely with the Eemian sea-level highstand(Marine Isotope Stage 5e;124–119 ka BP),the paper examines whether eustatic fluctuations may have triggered the fundamental change in Mount Etna’s magmatic behaviour,and suggests that a similar tendency may affect other volcanic centres in the region.展开更多
The compression test on rock-like specimens with prefabricated closed multi-fissures made by pulling out the embedded metal inserts in the precured period was done on the servo control uniaxial loading instrument. The...The compression test on rock-like specimens with prefabricated closed multi-fissures made by pulling out the embedded metal inserts in the precured period was done on the servo control uniaxial loading instrument. The influence of fissure inclination angle and distribution density on the failure characteristics of fissure bodies was researched. It was found that, the fissure inclination angle was the major influencing factor on the failure modes of fissure bodies. The different developmental states of micro-cracks would appear on specimens under different fissure inclination angles. However, the influence of fissure distribution density on the failure mode of fissure bodies was achieved by influencing the transfixion pattern of fissures. It was shown by the sliding crack model that, the effective shear, which drove the relative sliding of the fissure, was a function of fissure inclination angle and friction coefficient of the fissure surface. The strain-softening model of fissure bodies was established based on the mechanical parameters that were obtained by the test of rock-like materials under the same experimental condition. And the reliability of experimental results was identified by using this model.展开更多
Henan Pingdingshan No.10 mine is prone to both coal and gas outbursts.The E_(9-10)coal seam is the main coal-producing seam but has poor quality ventilation,thus making it relatively difficult for gas extraction.The F...Henan Pingdingshan No.10 mine is prone to both coal and gas outbursts.The E_(9-10)coal seam is the main coal-producing seam but has poor quality ventilation,thus making it relatively difficult for gas extraction.The F_(15)coal seam,at its lower section,is not prone to coal and gas outbursts.The average seam separation distance of 150 m is greater than the upper limit for underside protective seam mining.Based on borehole imaging technology for field exploration of coal and rock fracture characteristics and discrete element numerical simulation,we have studied the evolution laws and distribution characteristics of the coal and rock fissure field between these two coal seams.By analysis of the influential effect of group F coal mining on the E_(9-10)coal seam,we have shown that a number of small fissures also develop in the area some 150 m above the overlying strata.The width and number of the fissures also increase with the extent of mining activity.Most of the fissures develop at a low angle or even parallel to the strata.The results show that the mining of the F_(15)coal seam has the effect of improving the permeability of the E_(9-10)coal seam.展开更多
基金National Natural Science Foundation of China under Grant No.52108473Project of Shaanxi Engineering Technology Research Center for Urban Geology and Underground Space under Grant No.2025KT-03Key Project of Education Department of Shaanxi Province under Grant No.23JY042。
文摘Ground fissure,as a common geo-hazard,impairs the integrity of the site soil and affects the seismic performance of engineering structures.In this paper,a finite element(FE)model for subway stations in a ground fissure area was developed and validated by using experimental results.Numerical analyses were conducted to investigate the seismic response and failure mode of subway stations in a ground fissure area with different locations.Effects of ground fissure on deformations and internal forces of a station,soil pressures and soil plastic strains were discussed.The results showed that the seismic response of the station was significantly amplified by the ground fissure,and stations in the ground fissure area displayed obvious rocking deformation during earthquakes as compared to those in the area without fissures.It also was found that the soil yielding around the station,the dislocation occurring in the ground fissure area,and the dynamic amplification effect were more significant under vertical ground motion,which weakened the station’s ductility and accelerated its destruction process.
基金the CMEC Technology Incubation Project(No.CMEC-KJFH-2018-02)the National Science Foundation of China(No.41877250)+2 种基金the Fundamental Research Funds for the Central Universities,CHD(Nos.300102263512 and 300102260401)Shaanxi Science and Technology Coordination Innovation Project(No.2011KTZB03-02-02)the National Geological Survey of China(No.DD20160264)。
文摘Since the 1950's,212 earth fissures have been discovered in the Wei River Basin.During a field survey in 2016,an additional 48 earth fissures were discovered in Anren area,northeast of the Wei River Basin.The characteristics and formation mechanisms of these fissures were studied through field investigations,measurements,trench excavation,and drilling.On-site investigations indicated that these earth fissures were distributed along a fault-controlled geomorphic boundary.Fissures trended at 60°-80°NE and were divided into five groups.Trenches revealed multiple secondary fissures,exposing severe soil ruptures in the shallow earth surfaces.Drilling profiles revealed that earth fissures dislocated several strata,and resembled synsedimentary faults.Seismic reflection profiles revealed buried faults beneath the earth fissures.The Anren area fissures formed in the following three stages:regional extension that initially generated multiple buried faults;seismic activity rupturing multiple strata,resulting in multiple buried fractures;and finally,erosion processes that propagated the buried fractures to the surface,forming the current earth fissures.
基金supported by the National Key Research&Development Program of China(Grant No.2023YFC3008404)the Key Laboratory of Earth Fissures Geological Disaster,Ministry of Natural Resources,China(Grant Nos.EFGD20240609 and EFGD20240610).
文摘The recent upsurge in metro construction emphasizes the necessity of understanding the mechanical performance of metro shield tunnel subjected to the influence of ground fissures.In this study,a largescale experiment,in combination with numerical simulation,was conducted to investigate the influence of ground fissures on a metro shield tunnel.The results indicate that the lining contact pressure at the vault increases in the hanging wall while decreases in the footwall,resulting in a two-dimensional stress state of vertical shear and axial tension-compression,and simultaneous vertical dislocation and axial tilt for the segments around the ground fissure.In addition,the damage to curved bolts includes tensile yield,flexural yield,and shear twist,leading to obvious concrete lining damage,particularly at the vault,arch bottom,and hance,indicating that the joints in these positions are weak areas.The shield tunnel orthogonal to the ground fissure ultimately experiences shear failure,suggesting that the maximum actual dislocation of ground fissure that the structure can withstand is approximately 20 cm,and five segment rings in the hanging wall and six segment rings in the footwall also need to be reinforced.This study could provide a reference for metro design in ground fissure sites.
基金financially supported by the National Natural Science Foundation of China(No.41901132)the Natural Scientific Project of Guangxi Zhuang Autonomous Region(Nos.2019GXNSFAA185015,2021GXNSFBA220025)+1 种基金the Interdisciplinary Scientific Research Foundation of Guangxi University(No.2022JCC026)the Project of Key Laboratory of Early Rapid Identification,Prevention and Control of Geological Diseases in Traffic Corridor of High Intensity Earthquake Mountainous Area of Yunnan Province(No.KLGDTC-2021-01)。
文摘Granite residual soil slope is often destroyed,which poses great threats to Rong County in southeastern Guangxi,China.Heavy rainfall and fissures are the major triggering and internal factors.The fissure that controls the slope stability and the associated failure mechanisms remain unclear.The purpose of this study was to identify the controlling fissures through field investigation,elucidate the effect of its position,and analyze the failure process and hydrological response of residual soil slope through artificial flume model tests.The results comprised five aspects.(1)Surface weathering and unloading fissures could affect slope stability.(2)The failure processes with different fissure positions exhibited inconsistent characteristics.(3)The volume moisture content(VMC)had the most direct response at the fissure tip.The corresponding infiltration rate was the highest.The response time of pore water pressure(PWP)was longer than that of VMC.Fluctuations in PWP were associated with VMC and changes in the soil microstructure due to local deformation.(4)Slope failure was accompanied by serious soil erosion.This could be attributed to the infiltration direction and the interaction between soil and water.(5)Fissured soil slopes experienced five similar failure processes:sheet erosion and partial failure of the slope foot,occurrence of preferential flow and enlargement of the sliding area,creep deformation and tension fissure emergence,block sliding and gully erosion,and flow-slip.
基金the financial support of the National Key Research and Development Program of China(Grant No.2019YFC1509901).
文摘Fissured clays exhibit unique geotechnical behaviors,with the stiffness characteristics evolving dynamically in response to environmental changes.To address this issue,reported here is a systematic assessment of how dryingewetting(DW)cycles affect the small-strain stiffness characteristics of fissured clay.Resonant column tests are taken to examine the nonlinear attenuation behavior of the small-strain shear modulus(SSSM)and damping ratio of fissured clay under various DW cycle and consolidation pressure(25e200 kPa)conditions.Scanning electron microscopy(SEM)and computed tomography(CT)are employed to reveal the microstructure of fissured clay.The HardineDrnevich(H-D)model is used to describe the decay law of its SSSM,and the small strain stiffness characteristics of fissured soil are analyzed in view of damage mechanics.The results show that the SSSM of the fissured clay decreases as the DWcycles increase,with the greatest attenuation at original soil state.The damping ratio exhibits an incremental trend with escalating strain and a higher number of DW cycles.Regarding damage,DW cycles can lead to the formation of microcracks in the sample,and the aggregates disperse into smaller aggregates,which then aggregates again,resulting in structural damage.The damage variables of the samples under various confining pressures and DW cycles are analyzed based on the principle of strain damage.Finally,the volume changes and the distribution of different pore sizes obtained through CT are analyzed to investigate the stiffness attenuation under DW cycles.Additionally,the study examines the propagation direction of secondary cracks induced by primary fissures,which will play an important role in reduction of the stiffness.Our investigations contribute to understanding of soil mechanics and practical applications in areas where fissured clay is prevalent.
基金supported by the National Science and Technology Major Project(2024ZD1000705)the Basic Research Project of Liaoning Provincial Department of Education-Key Project of Independent Topic Selection(LJ212410147007).
文摘Fissured coal mass under triaxial unloading condition exhibits higher burst potential than the triaxial loading condition,which poses challenge to safety and productivity of resources extraction and underground space utilization.To comprehensively understand the mechanism of unloading-induced burst during excavation process,this study investigated the fracture and energy evolution of samples with different fissure types such as single,two parallel,and two coplanar-parallel using PFC2D modelling.Triaxial loading tests were conducted to determine the compressive strengths and other parameters.With increase of fissure inclination angle,the triaxial compressive strength decreases forβ=0°-30°,and then increase forβ=30°-90°.The strength of samples with two coplanar-parallel fissures is the highest.Fissure can significantly change the distribution of fracture and elastic energy.Secondary cracks were generated starting from both ends of the fissure.Forβ=0°-60°,low elastic strain energy area was produced around the fissure along the loading direction.The elastic strain energy is transferred to the outside of fissures.Forβ=75°-90°,only a small amount of high elastic strain energy was generated on both sides of the fissure.The fracture expansion under unloading conditions occurred due to tensile stress T caused by unloading differential rebound deformation and the shear stress on the fissure surface.
基金supported by the National Key R&D Program of China(Grant No.2018YFC1504802)the National Natural Science Foundation of China(Grant No.52074042)。
文摘Taking the Pusa Collapse in Nayong County,Guizhou Province,China as a case study,this paper investigates the impact of multi-layer coal mining on karst mountains characterized by deep fissures.Based on field investigations and employing discrete element numerical simulations,the deformation and failure mechanisms of karst mountain containing deep and large fissures under multi-seam mining conditions was investigated.The influence of the direction of coal seam extraction and the sequence of extraction between multiple coal seams on the failure modes of karst mountain with deep and large fissures was studied.The results indicate that underground mining primarily manifests in the development of mininginduced fissures in the mountain body,subsidence and deformation of slope masses,and triggering the expansion of existing fissures,further driving overall deformation and damage to the slopes.Deep and large fissures control the deformation and failure modes of the slopes,with closer and longer deep and large fissures near the slope surface exerting greater influence on the slope mass.The impact of mining in the same coal seam direction on the slopes is mainly reflected in the process of slope deformation and failure.Downslope mining directly leads to overall subsidence of the slope mass,squeezing the front and lower parts of the slope mass.Upslope mining initially causes the foot of the slope to sink and the entire slope mass to move outward,and continuous mining leads to overall settlement and downward compression deformation of the slope.The sequence of mining between multiple coal seams mainly affects the overall and local deformation values of the slope mass.Downward mining leads to increased overall subsidence of the slope mass and exacerbates the backward tilt of the slope top.
基金supported by the National Natural Science Foundation of China(Project No.52074123).
文摘To explore the effects of freeze‒thaw cycles on the mechanical properties and crack evolution of fissured sandstone,biaxial compression experiments were carried out on sandstone subjected to freeze‒thaw cycles to characterize the changes in the physical and mechanical properties of fissured sandstone caused by freeze‒thaw cycles.The crack evolution and crack change process on the surface of the fissured sandstone were recorded and analysed in detail via digital image technology(DIC).Numerical simulation was used to reveal the expansion process and damage mode of fine-scale cracks under the action of freeze‒thaw cycles,and the simulation results were compared and analysed with the experimental data to verify the reliability of the numerical model.The results show that the mass loss,porosity,peak stress and elastic modulus all increase with increasing number of freeze‒thaw cycles.With an increase in the number of freeze‒thaw cycles,a substantial change in displacement occurs around the prefabricated cracks,and a stress concentration appears at the crack tip.As new cracks continue to sprout at the tips of the prefabricated cracks until the microcracks gradually penetrate into the main cracks,the displacement cloud becomes obviously discontinuous,and the contours of the displacement field in the crack fracture damage area simply intersect with the prefabricated cracks to form an obvious fracture.The damage patterns of the fractured sandstone after freeze‒thaw cycles clearly differ,forming a symmetrical"L"-shaped damage pattern at zero freeze‒thaw cycles,a symmetrical"V"-shaped damage pattern at 10 freeze‒thaw cycles,and a"V"-shaped damage pattern at 20 freeze‒thaw cycles.After 20 freeze‒thaw cycles,a"V"-shaped destruction pattern and"L"-shaped destruction pattern are formed;after 30 freeze‒thaw cycles,an"N"-shaped destruction pattern is formed.This shows that the failure mode of fractured sandstone gradually becomes more complicated with an increasing number of freeze‒thaw cycles.The effects of freeze‒thaw cycles on the direction and rate of crack propagation are revealed through a temperature‒load coupled model,which provides an important reference for an in-depth understanding of the freeze‒thaw failure mechanisms of fractured rock masses.
基金Supported by Guangdong Provincial Science and Technology Plan Project,No.2022A0505050065Guangdong Natural Science Foundation,No.2022A1515011632.
文摘BACKGROUND Laparoscopic hepatectomy is a proven safe and technically feasible approach for liver tumor resection,but laparoscopic anatomical SVIII resection(LASVIIIR)remains rarely reported due to poor accessibility,difficult exposure,and the deep-lying Glissonean pedicle.This study examined the safety,feasibility,and perio-perative outcomes of LASVIIIR via a middle hepatic fissure approach at our in-stitution.AIM To investigate the safety,feasibility,and perioperative outcomes of LASVIIIR via a middle hepatic fissure approach at our institution.METHODS From November 2017 to December 2022,all patients with a liver tumor who underwent LASVIIIR were enrolled.The perioperative outcomes and postope-rative complications were evaluated.RESULTS Thirty-four patients underwent LASVIIIR via a middle hepatic fissure approach from the side or cranio side and were included.The mean operation time was 164±54 minutes,and the intra-operative blood loss was 100 mL(range:20-1000 mL).The mean operative times were,respectively,152±50 minutes and 222±29 minutes(P=0.001)for the caudal side and cranial side approaches.In addition,the median blood loss volumes were 100 mL(range:20-300 mL)and 250 mL(range:20-1000 mL),respectively,for the caudal and cranial sides(P=0.064).Three patients treated using the cranial side approach experienced bile leakage,while 1 patient treated using the caudal side approach had subphrenic collection and underwent percutaneous drainage to successfully recover.There were no differences regarding postoperative hospital stays for the caudal and cranial side approaches[9(7-26)days vs 8(8-19)days](P=0.226).CONCLUSION LASVIIIR resection remains a challenging operation,but the middle hepatic fissure approach is a reasonable and easy-to-implement technique.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.41972283)the Fundamental Research Funds for the Central Universities of Central South University(Grant No.2021zzts0287)the China Scholarship Council(Grant No.202206370109).
文摘In the engineering practices,it is increasingly common to encounter fractured rocks perturbed by temperatures and frequent dynamic loads.In this paper,the dynamic behaviors and fracture characteristics of red sandstone considering temperatures(25℃,200℃,400℃,600℃,and 800℃)and fissure angles(0°,30°,60°,and 90°)were evaluated under constant-amplitude and low-cycle(CALC)impacts actuated by a modified split Hopkinson pressure bar(SHPB)system.Subsequently,fracture morphology and second-order statistics within the grey-level co-occurrence matrix(GLCM)were examined using scanning electron microscopy(SEM).Meanwhile,the deep analysis and discussion of the mechanical response were conducted through the synchronous thermal analyzer(STA)test,numerical simulations,one-dimensional stress wave theory,and material structure.The multiple regression models between response variables and interactive effects of independent variables were established using the response surface method(RSM).The results demonstrate the fatigue strength and life diminish as temperatures rise and increase with increasing fissure angles,while the strain rate exhibits an inverse behavior.Furthermore,the peak stress intensification and strain rate softening observed during CALC impact exhibit greater prominence at increased fissure angles.The failure is dominated by tensile damage with concise evolution paths and intergranular cracks as well as the compressor-crushed zone which may affect the failure mode after 400℃.The second-order statistics of GLCM in SEM images exhibit a considerable dependence on the temperatures.Also,thermal damage dominated by thermal properties controls the material structure and wave impedance and eventually affects the incident wave intensity.The tensile wave reflected from the fissure surface is the inherent mechanism responsible for the angle effect exhibited by the fatigue strength and life.Ultimately,the peak stress intensification and strain rate softening during impact are determined by both the material structure and compaction governed by thermal damage and tensile wave.
基金funded by the National Science Foundation of China(Nos.2022XAGG0400,42207202,42293351)the Open Fund of the Key Laboratory of Earth Fissures Geological Disaster,Ministry of Natural Resources,Geological Survey of Jiangsu Province,China(No.EFGD20240604)+2 种基金the Open Fund of the Observation and Research Station of Ground Fissure and Land Subsidence,Ministry of Natural Resources(No.GKF2024-06)the Fundamental Research Funds for the Central Universities of China University of Geosciences,Beijing(No.2-9-2021-014)the Fundamental Research Funds for the Central Universities of Chang'an University(No.300102264501-01)。
文摘Nearly 1100 fissures have formed on the Hebei Plain in China.Within the Yellow RiverQinghe River-Zhanghe River shallow buried paleochannel band on the plain,93 ground fissures controlled by paleochannels have developed,of which the Wuyi-Fuping ground fissure is a typical paleochannel-controlled fissure located in Hengshui,Hebei Province,with a total length of 3 km,a dominant strike of NE78°,and nearly upright in the shallow layer.The surface damage observed in this fissure primarily manifests as beaded pits,and its activity shows distinct segmentation characteristics.On the trench profiles,the offset distance of shallow layers remains consistently around 20 cm within the depth range of 0 to-3 m.An evident flexure is observed in the strata at depths ranging from-4.5 to-7 m.The drilling profile reveals that there is an absence of dislocations in the deeper strata.Nonetheless,the shallow seismic physical profiles unveil the presence of underlying faults beneath the study area,underscoring the intricate formation process and genesis mechanism of the Wuyi-Fuping ground fissure.Firstly,the formation and evolution of the Qingling River's paleochannel were shaped by the actions of fault blocks and underlying faults.The interplay of the regional stress field,fault block movement,and fault activity played pivotal roles in driving the development of this paleochannel.Secondly,the paleochannel exerts a controlling influence on the development location and severity of the fissure.During pumping,the confined aquifer within the paleochannel undergoes water loss and compression,resulting in the formation of a surface subsidence funnel.When the tensile stress surpasses the soil's tensile strength at the funnel's edge,the soil fractures give rise to a ground fissure.Finally,large amounts of surface water generated by heavy rainfall and irrigation can cause existing hidden ground fissures to rupture,emerge,and expand.This paper provides a heretofore generally unknown example,promotes research on the mechanisms of paleochannel-controlled fissures,and has guiding significance for disaster prevention and reduction in this area.
基金supported by National Natural Science Foundation of China (Grant NOs. 41877250, 41272284)the Key Laboratory of Earth Fissures Geological Disaster, Ministry of Natural Resources (No. EFGD20240601)the Natural Science Foundation of Shaanxi Province-General Project (grant number 2023-JC-YB-231)-Suitability Evaluation of Precast Prestressed Underground Comprehensive Pipe Gallery Crossing Active Ground Fissure。
文摘The Fenwei Basin, covered by loess, experiences severe ground fissure disasters. These disasters disrupt the continuity of the loess and pose significant threats to engineering construction safety along transportation routes. Nevertheless, the crack characteristics and the influence zone of ground fissures in the loess layer remain inadequately investigated. To effectively prevent and control ground fissure disasters, physical model tests and the PFC(particle flow code) numerical simulation method are used to investigate the crack mechanism of buried ground fissures in the loess layer. The results show that there are two main cracks in the layer profile, which have a Y-shape morphology. As the dip angle of the preset cracks increased from 60° to 90°, the main deformation zone at the surface gradually shifted towards the footwall. The process of crack propagation from depth to surface is divided into five stages. Additionally, the results confirm the accuracy of the width of the rupture zone d2in the footwall calculated by the cantilever beam theory. These findings can offer theoretical guidance for determining the avoidance distance of ground fissures in loess regions, as well as for implementing disaster prevention and corresponding control measures for various stages of buried ground fissure propagation.
基金supported by the Major Program of the National Natural Science Foundation of China(No.52394191)the Fundamental Research Funds for China University of Mining and Technology(Beijing):Doctoral Top-notch Innovative Talents Cultivation Fund(No.BBJ2023018,BBJ2023023)the Open Fund of State Key Laboratory of Water Resource Protection and Utilization in Coal Mining(No.GJNY-20-113-20).
文摘The Inner Mongolia mining area in western China are characterized by the development of numerous penetrating fissures,resulting in severe land damage.It is significant to reveal the underlying evolution mechanism and identify treatment timing for restoring the ecological environment.The Guanbanwusu mining subsidence area in Inner Mongolia,China was selected as the research case for this study.The evolution mechanism of different penetrating fissures was revealed by field measurement,physical simulation and theoretical analysis.The treatment timing prediction model for the mining subsidence area was established based on the enhanced Weibull time function.The results show that the ground fissures are mainly step-type and collapse-type fissures.The breaking form of overlying strata determines their vertical opening and horizontal dislocation.The high mining intensity in the western mining area results in a shortened period of dynamic fissure expansion and reduced closure degree.The damage extent of the overlying strata exhibits zoning characteristics both vertically and horizontally.The relative standard deviation of the prediction model is only 3.7%.Concurrently,the prediction model is employed to determine the optimal timing for treatment in the study area,estimated to be 259 days.Subsequently,once this threshold is reached,the study area undergoes treatment and restoration of its e cological environment.This study addresses the knowledge gap in this field by highlighting the interconnectedness between rock strata structure and evolution mechanism of penetrating fissures,thereby providing a method for determining the treatment timing in mining subsidence areas.
基金supported by the National Natural Science Foundation of China(Nos.52225402 and U1910206).
文摘Heat transfer and temperature evolution in overburden fracture and ground fissures are one of the essential topics for the identification of ground fissures via unmanned aerial vehicle(UAV) infrared imager. In this study, discrete element software UDEC was employed to investigate the overburden fracture field under different mining conditions. Multiphysics software COMSOL were employed to investigate heat transfer and temperature evolution of overburden fracture and ground fissures under the influence of mining condition, fissure depth, fissure width, and month alternation. The UAV infrared field measurements also provided a calibration for numerical simulation. The results showed that for ground fissures connected to underground goaf(Fissure Ⅰ), the temperature difference increased with larger mining height and shallow buried depth. In addition, Fissure Ⅰ located in the boundary of the goaf have a greater temperature difference and is easier to be identified than fissures located above the mining goaf. For ground fissures having no connection to underground goaf(Fissure Ⅱ), the heat transfer is affected by the internal resistance of the overlying strata fracture when the depth of Fissure Ⅱ is greater than10 m, the temperature of Fissure Ⅱ gradually equals to the ground temperature as the fissures’ depth increases, and the fissures are difficult to be identified. The identification effect is most obvious for fissures larger than 16 cm under the same depth. In spring and summer, UAV infrared identification of mining fissures should be carried out during nighttime. This study provides the basis for the optimal time and season for the UAV infrared identification of different types of mining ground fissures.
文摘The main objective of this study is to determine the hydrogeochemical specificities of the groundwater of the Angovia mine operating permit, located in the Yaouré mountains in the center-west of Côte d’Ivoire. To do so, descriptive and multivariate statistical analysis methods with the SOM (Self Organizing Maps) algorithm were applied to the physicochemical parameters of 17 boreholes using the calcite (ISC) and dolomite (ISD) saturation indices. The results obtained have shown that the groundwater in the Angovia mine operating permit area has an average temperature of 27.52°C (long rainy season) and 27.87°C (long dry season) and has an average pH of 7.09 ± 0.35 during the main rainy season and 7.32 ± 0.35 during the main dry season. They are mineralized with an average electrical conductivity of 505.98 ± 302.85 μS/cm during the long rainy season and with 450.33 ± 233.74 μS/cm as average during the long dry season. The main phenomena at the origin of groundwater mineralization are water residence time, oxidation-reduction and surface inflow. The study of the relative age of the water shows that the groundwater in the Angovia mine operating permit area is mainly undersaturated with respect to calcite and dolomite. They are therefore very old in the aquifer with a slow circulation speed during the long rainy season and the long dry season.
文摘Chronic anal fissure(CAF)is a painful tear or crack which occurs in the anoderm.The optimal algorithm of therapy for CAF is still debated.Lateral internal sphincterotomy(LIS)is a surgical treatment,considered as the'gold standard'therapy for CAF.It relieves CAF symptoms with a high rate of healing.Chemical sphincterotomy(CS)with nitrates,calcium blockers or botulinum toxin(BTX)is safe,with the rapid relief of pain,mild sideeffects and no risk of surgery or anesthesia,but is a statistically less effective therapy for CAF than LIS.This article considers if aggressive treatment should only be offered to patients who fail pharmacological sphincterotomy.Aspects of anal fissure etiology,epidemiology and pathophysiology are considered with their meaning for further management of CAF.A molecular model of chemical interdependence significant for the chemistry of CAF healing is examined.Its application may influence the development of optimal therapy for CAF.BTX is currently considered the most effective type of CS and discussion in this article scrutinizes this method specifically.Although the effectiveness of BTXvs LIS has been discussed,the essential focus of the article concerns identifying the best therapy application for anal fissure.Elements are presented which may help us to predict CAF healing.They provide rationale for the expansion of the CAF therapy algorithm.Ethical and economic factors are also considered in brief.As long as the patient is willing to accept the potential risk of fecal incontinence,we have grounds for the'gold standard'(LIS)as the first-line treatment for CAF.The author concludes that,when the diagnosis of the anal fissure is established,CS should be considered for both ethical and economic reasons.He is convinced that a greater understanding and recognition of benign anal disorders by the GP and a proactive involvement at the point of initial diagnosis would facilitate the consideration of CS at an earlier,more practical stage with improved outcomes for the patient.
文摘BACKGROUND Lateral internal sphincterotomy is still the approach of choice for the treatment of chronic anal fissure(CAF)with internal anal sphincter(IAS)hypertonia,but it is burdened by high-risk postoperative faecal incontinence(FI).Sphincter saving procedures have recently been reconsidered as treatments to overcome this risk.The most employed procedure is fissurectomy with anoplasty,eventually associated with pharmacological sphincterotomy.AIM To evaluate whether fissurectomy and anoplasty with botulinum toxin injection improves the results of fissurectomy and anoplasty alone.METHODS We conducted a case-control study involving 30 male patients affected by CAF with hypertonic IAS who underwent fissurectomy and anoplasty with V-Y cutaneous flap advancement.The patients were divided into two groups:Those in group I underwent surgery alone,and those in group II underwent surgery and a botulinum toxin injection directly into the IAS.They were followed up for at least 2 years.The goals were to achieve complete healing of the patient and to assess the FI and recurrence rate along with manometry parameters.RESULTS The intensity and duration of post-defecatory pain decreased significantly in both groups of patients starting with the first defecation,and this reduction was higher in group II.Forty days after surgery,we achieved complete wound healing in all the patients in group II but only in 80%of the patients in group I(P<0.032).We recorded 2 cases of recurrence,one in each group,and both healed with conservative therapy.We recorded one temporary and low-grade postoperative case of“de novo”FI.Manometry parameters reverted to the normal range earlier for group II patients.CONCLUSION The injection of botulinum toxin A in association with fissurectomy and anoplasty with a V-Y advancement flap improves the results of surgery alone in patients affected by CAF with IAS hypertonia.
文摘One of the most intriguing aspects of the evolution of Mount Etna(eastern Sicily)is the switch from a fissuretype shield volcano coincident with the Ionian coast to an inland cluster of nested stratovolcanoes close to the currently active centre.Previous geological studies infer that the switch reflects a tectonically-driven rearrangement of the major border faults that direct the Etnean plumbing system,loosely dated at around 125 ka BP.New offshore structural studies throw this prevailing view into question,whilst a revised chronological framework indicates that the transformation from fissure-to central-type activity was abrupt,effectively occurring 129–126 ka BP.In recognising that this period corresponds closely with the Eemian sea-level highstand(Marine Isotope Stage 5e;124–119 ka BP),the paper examines whether eustatic fluctuations may have triggered the fundamental change in Mount Etna’s magmatic behaviour,and suggests that a similar tendency may affect other volcanic centres in the region.
基金Project (10972238) supported by the National Natural Science Foundation of ChinaProject supported by the Open-End Fund of the Valuable and Precision Instruments of Central South University
文摘The compression test on rock-like specimens with prefabricated closed multi-fissures made by pulling out the embedded metal inserts in the precured period was done on the servo control uniaxial loading instrument. The influence of fissure inclination angle and distribution density on the failure characteristics of fissure bodies was researched. It was found that, the fissure inclination angle was the major influencing factor on the failure modes of fissure bodies. The different developmental states of micro-cracks would appear on specimens under different fissure inclination angles. However, the influence of fissure distribution density on the failure mode of fissure bodies was achieved by influencing the transfixion pattern of fissures. It was shown by the sliding crack model that, the effective shear, which drove the relative sliding of the fissure, was a function of fissure inclination angle and friction coefficient of the fissure surface. The strain-softening model of fissure bodies was established based on the mechanical parameters that were obtained by the test of rock-like materials under the same experimental condition. And the reliability of experimental results was identified by using this model.
基金financially supported by the State Key Basic Research Program of China(No.2011CB201203)the State Key Special Program of China(No.2011ZX05040-001-005)the National Natural Science Foundation of China(No.51374256)
文摘Henan Pingdingshan No.10 mine is prone to both coal and gas outbursts.The E_(9-10)coal seam is the main coal-producing seam but has poor quality ventilation,thus making it relatively difficult for gas extraction.The F_(15)coal seam,at its lower section,is not prone to coal and gas outbursts.The average seam separation distance of 150 m is greater than the upper limit for underside protective seam mining.Based on borehole imaging technology for field exploration of coal and rock fracture characteristics and discrete element numerical simulation,we have studied the evolution laws and distribution characteristics of the coal and rock fissure field between these two coal seams.By analysis of the influential effect of group F coal mining on the E_(9-10)coal seam,we have shown that a number of small fissures also develop in the area some 150 m above the overlying strata.The width and number of the fissures also increase with the extent of mining activity.Most of the fissures develop at a low angle or even parallel to the strata.The results show that the mining of the F_(15)coal seam has the effect of improving the permeability of the E_(9-10)coal seam.
