The stability of the tunnel portal slope is crucial for ensuring safe tunnel construction.Thus,a sound stability evaluation is of significance.Given the unique geological characteristics of tunnel portal slopes,it is ...The stability of the tunnel portal slope is crucial for ensuring safe tunnel construction.Thus,a sound stability evaluation is of significance.Given the unique geological characteristics of tunnel portal slopes,it is necessary to establish a specific evaluation indicator system that differs from those used for ordinary slopes.Based on the unascertained measure method,uncertainties in the indicator are addressed by introducing the left and right half cloud asymmetric cloud model to optimize the linear membership function.The subjectivity of confidence criterion level identification is also improved by using the Euclidean distance method.Thus,a stability evaluation model for the tunnel portal slope is established based on the improved unascertained measure method.Finally,using the collected tunnel portal slope data,the results of four evaluation methods are compared with the safety factor levels.The evaluation methods include the traditional unascertained measure method,the method improved by using the left and right half cloud asymmetric cloud model,the method improved by using the Euclidean distance method,and the method improved by using both the left and right half cloud asymmetric cloud model and the Euclidean distance method.The results show that the accuracy rates of these four methods are 50%,55%,85%,and 90%,respectively.Among them,the joint improvement method has the slightest deviation,with only one level,while the other three methods had deviations of two levels.This result verifies the stability and effectiveness of the joint improvement method,providing a reference for tunnel portal slope stability evaluation.展开更多
Deep-seated toppling in the upper reaches of the Lancang River,southwest China involves deformations exceeding 100 m in depth.The slope deformation is initiated by river downcutting and evolves distinctive characteris...Deep-seated toppling in the upper reaches of the Lancang River,southwest China involves deformations exceeding 100 m in depth.The slope deformation is initiated by river downcutting and evolves distinctive characteristics with a depth of river incision.In this study,we propose a system for evaluating the stability of deep-seated toppled slopes in different evolutionary stages.This system contains identification criteria for each evolutionary stage and provides the corresponding stability evaluation methods.Based on the mechanical and kinematic analysis of slope blocks,the specific stage of slope movement can be identified in the field through outcrop mapping,in situ tests,surface displacement monitoring,and adit and borehole explorations.The stability evaluation methods are established based on the limiting equilibrium theory and the strain compatibility between the undisturbed zone and the toppled zone.Finally,several sample slopes in different evolution stages have been investigated to verify the applicability and accuracy of the proposed stability evaluation system.The results indicate that intense tectonic activity and rapid river incision lead to a maximum principal stress ratio exceeding 10 near the slope surface,thus triggering widespread toppling deformations along the river valley.When considering the losses of joint cohesion during the further rotation process,the safety factor of the slope drops by 7%e28%.The self-stabilization of toppling deformation can be recognized by the layer symmetry configuration after the free rotation of the deflected layers.Intensely toppled rock blocks mainly suffer sliding failures beyond the layer symmetry condition.The factor of safety of the K73 rockslide decreased from 1.17 to 0.87 by considering the development of the potential sliding surface and the toesaturated zone.展开更多
Real-time quantitative PCR(qPCR)is a reliable and widely used technique for analyzing the expression profiles of target genes in different species,and reference genes with stable expressions have been introduced for t...Real-time quantitative PCR(qPCR)is a reliable and widely used technique for analyzing the expression profiles of target genes in different species,and reference genes with stable expressions have been introduced for the normalization of the data.Therefore,stability evaluation should be considered as the initial step for qPCR experiments.The fall armyworm Spodoptera frugiperda(J.E.Smith)(Lepidoptera:Noctuidae)is a polyphagous pest that consumes many plant species and seriously threatens corn production around the world.However,no studies thus far have examined the stability of reference genes in this pest.In this study,the expression profiles of the eight candidate reference genes of Actin,elongation factor 1 alpha(EF1α),elongation factor 2(EF2),glyceraldehyde-3-phosphate dehydrogenase(GAPDH),ribosomal protein L3(RPL3),ribosomal protein L13(RPL13),alpha-tubulin(α-TUB),and beta-1-tubulin(β-1-TUB)were obtained from S.frugiperda in different samples and the stability was evaluated byΔCt,BestKeeper,geNorm,NormFinder,and RefFinder methods.The results of pairwise variation(V)calculated by GeNorm indicated two reference genes could be selected for normalization.Therefore,the combinations of the most stable reference genes for different experimental conditions of S.frugiperda were shown as follows:EF2 and RPL13 for developmental stages,RPL3 andβ-1-TUB for larval tissue samples,EF2 and EF1αfor the larval samples treated with different temperatures,RPL3 and EF1αfor the larval samples under starvation stress,and RPL13 and EF1αfor all the samples.Our results lay the foundation for the normalization of qPCR analyses in S.frugiperda and could help guarantee the accuracy of subsequent research.展开更多
Rock slide is one of the common geohazard in the Three Gorges Reservoir area, and it affects the shipping of the Yangtze River and the safety of people living on the banks. In order to investigate the internal fractur...Rock slide is one of the common geohazard in the Three Gorges Reservoir area, and it affects the shipping of the Yangtze River and the safety of people living on the banks. In order to investigate the internal fracturing mechanism of rock mass, distributed microseismic monitoring network was arranged with 15 three component geophones(3C geophones), deployed at borehole and out of the sliding mass in the unstable Dulong slope. Stein Unbiased Risk Estimation(SURE) method was used to noise suppression for the microseismic record, and decomposition parameters of the Continuous Wavelet Transform(CWT) were determined with maximum energy of correlation coefficient(MECC) method. The signal-to-noise ratio was tripled after the process, and source parameters are obtained with full waveform inversion. The rupture volume model was counted by the irregular grid statistics with the events’ density. It shows that the rock slide is of a small scale and composed of a single block. Moreover, the relationship among microseismicity, displacement and rainfall were discussed in the paper. The deformation rate was dramatically changed in the period of intensive events. There is a good consistency especially in the rainfall period. Although there is a time delay, continuous rainfall is more likely to cause the increase of microseismic events. The results show that the Dulong slope is a shallow rock slide in the state of creep deformation, and the rupture mechanism of the rock mass is left-lateral normal fault with shear failure. The research provides more key information for the early warning and prevention of rock slides and helps to reduce the risk of geohazards.展开更多
One of the main issues in tree stability evaluations is the scheduling of adequate monitoring programs. Generally, after a tree analysis, an arborist indicates the required maintenance operations and the timing for pe...One of the main issues in tree stability evaluations is the scheduling of adequate monitoring programs. Generally, after a tree analysis, an arborist indicates the required maintenance operations and the timing for periodical inspection. Field conditions, tree species and biomechanical defects influence the plan. Three old trees （Populus spp. and Celtis australis） located within Golf Club Verona （Sommacampagna, Italy） were monitored periodically from 2010 to present. In addition to visual assessment, authors used sonic tomography to evaluate development of internal defects and planning the maintenance. The aim of this work is to identify a methodology for observing significant difference in tomograms, in order to understand the appropriate interval between instrumental analyses.展开更多
A scientific and rational evaluation on road-region ecosystem stability is the premise to properly deal with the relationship between highway constructing and ecological environment protecting to a sustainable develop...A scientific and rational evaluation on road-region ecosystem stability is the premise to properly deal with the relationship between highway constructing and ecological environment protecting to a sustainable development. Based on the connotative meaning and the procedure of evaluation on road-region ecosystem stability, this paper studied the principles and the method on determining the evaluation index system on road-region ecosystem stability. It put forward an index system for assessing road-region ecosystem stability as a reference. On the basis of detailed analyze of the multidimensional space of road-region ecosystem, a new multi-objective comprehensive evaluation method for road-region ecosystem stability is presented and a calculation tormula for multi-objective comprehensive level of road-region ecosystem stability. This method was used to evaluate road-region ecosystem stability of Lin-Chang highway. This method possessed definite theoretical value and reliability in practice.展开更多
In underground mining,especially in entry-type excavations,the instability of surrounding rock structures can lead to incalculable losses.As a crucial tool for stability analysis in entry-type excavations,the critical...In underground mining,especially in entry-type excavations,the instability of surrounding rock structures can lead to incalculable losses.As a crucial tool for stability analysis in entry-type excavations,the critical span graph must be updated to meet more stringent engineering requirements.Given this,this study introduces the support vector machine(SVM),along with multiple ensemble(bagging,adaptive boosting,and stacking)and optimization(Harris hawks optimization(HHO),cuckoo search(CS))techniques,to overcome the limitations of the traditional methods.The analysis indicates that the hybrid model combining SVM,bagging,and CS strategies has a good prediction performance,and its test accuracy reaches 0.86.Furthermore,the partition scheme of the critical span graph is adjusted based on the CS-BSVM model and 399 cases.Compared with previous empirical or semi-empirical methods,the new model overcomes the interference of subjective factors and possesses higher interpretability.Since relying solely on one technology cannot ensure prediction credibility,this study further introduces genetic programming(GP)and kriging interpolation techniques.The explicit expressions derived through GP can offer the stability probability value,and the kriging technique can provide interpolated definitions for two new subclasses.Finally,a prediction platform is developed based on the above three approaches,which can rapidly provide engineering feedback.展开更多
0 INTRODUCTION Submarine slope slides refer to a geological process occurring on submarine slopes or continental margin slopes,where a large amount of sediment or rock layers on the slope lose stability and slide down...0 INTRODUCTION Submarine slope slides refer to a geological process occurring on submarine slopes or continental margin slopes,where a large amount of sediment or rock layers on the slope lose stability and slide downward along the sliding surface(Kamran et al.,2023;Tong et al.,2023;Hampton et al.,1996).展开更多
Embankment stability is the primary problem for the expressway construction in permafrost regions.The proposed Qinghai-Tibet Expressway(QTE)is planned to construct along the Qinghai-Tibet Project Corridor.Confronted w...Embankment stability is the primary problem for the expressway construction in permafrost regions.The proposed Qinghai-Tibet Expressway(QTE)is planned to construct along the Qinghai-Tibet Project Corridor.Confronted with harsh environmental condition and intense heat exchange between earth and atmosphere,it is necessary to predict and evaluate the stability of the proposed QTE.In this study,the factors affecting the embankment stability are analyzed firstly.And then,a scheme for the stability evaluation of the embankment is established.Finally,the evaluation scheme is used for the pre-evaluation of the stability for the proposed QTE with different geothermal regulation measures(GRMs).The results indicate that the influencing factors include climatic environment,permafrost property,engineering condition and geological condition,and among them,engineering condition and permafrost property are the main influence factors for embankment stability.The stability of the proposed QTE varies greatly in the different geomorphological regions.The application effect and contribution to embankment stability of the existing GRMs are different,and using GRMs cannot completely overcome the influence of various factors on expressway stability.In the construction process,different GRMs should be adopted depending on the geomorphological environment where the embankment is located to ensure the embankment stability.展开更多
Slope is the carrier of geological disasters. Local slope deformation and destruction are the beginning of the formation of collapse, landslide and debris flow. For the evaluation of slope stability, it is the purpose...Slope is the carrier of geological disasters. Local slope deformation and destruction are the beginning of the formation of collapse, landslide and debris flow. For the evaluation of slope stability, it is the purpose of this evaluation to distinguish unstable, unstable, basically stable and stable slopes in the town area of Taoyuan Township. Combined with field ground investigation and remote sensing images, the data of soil thickness, stratum lithology, terrain slope, slope structure type, regional rainfall, geological structure, human activities and slope height of each slope are collected, and the slope stability evaluation is carried out for rocky slopes and soil slopes. The expert consultation method is used to assign weight and grade assignment to each factor, and the fuzzy comprehensive evaluation method is used to evaluate the stability of 95 natural slopes divided by Taoyuan Township. Based on the evaluation results, the slope stability zoning map of the study area is drawn, and the regional slope stability distribution law is summarized. The evaluation results can provide basic information for local geological disaster management, urban planning, road planning, etc.展开更多
Salt-cavern underground gas storage is technically faced with non-uniform distribution of stratified salt rocks,complex solution mining mechanism,difficult control of solution mining process,less operation safety and ...Salt-cavern underground gas storage is technically faced with non-uniform distribution of stratified salt rocks,complex solution mining mechanism,difficult control of solution mining process,less operation safety and stability of caverns and difficult reconstruction and utilization of old caverns.In view of these technical difficulties,the design concept was fully updated based on the design experience and field practice of Jintan gas storage in Jiangsu,for purpose of maximizing salt layer utilization ratio,improving solution mining efficiency,shortening construction time and ensuring cavity safety.Based on the updated design concept,five series of key technologies were proposed in site evaluation,cavern design and control,stability assessment and storage capacity parameter design,old cavern screening and utilization,and gas storage operation and monitoring.The following results were obtained from the actual application of these key technologies to the Jintan gas storage.First,the actual drilling coincidence rate of geological program is high.Second,the cavern is morphologically coincident with the design.Third,the cavern deformation retract rate is in line with the stability evaluation result.Fourth,old caverns are successfully reconstructed and utilized.Fifth,the arrangement of the monitoring network ensures the operation safety of salt-cavern underground gas storage and makes an important contribution to the peak shaving and supply guarantee of natural gas in the Yangtze River Delta region.In conclusion,the research results provide guidance for the design and engineering implementation of salt-cavern underground gas storage construction program,as well as a theoretical and technical support for the construction of similar gas storages.展开更多
According to the rock engineering property and stability of high-steep open-pitslopes, various factors were collected on the basis of rock engineering system (RSE) theory,and the interaction matrix of stability evalua...According to the rock engineering property and stability of high-steep open-pitslopes, various factors were collected on the basis of rock engineering system (RSE) theory,and the interaction matrix of stability evaluation was established.Then, the stabilityevaluation index (S_p) of the slope was put forward.Ranges of the S_p value and the correspondingstable state were given on the basis of thirty-six samples.It is found that the followingrelationships exist: unstable (easy landslide): S_p<-0.20; mid-stable (may be landslide):-0.20<S_p<0.63; stable (no landslide): S_p>0.63.Finally, the stability evaluation indexwas applied on the high-steep open-pit slope of one mine.Analysis results and monitoringdata indicate that the index meets the necessity of the property of slope engineering, and ithas an important engineering purpose for landslide forecasting of high-steep slopes.展开更多
Polymer aging under environmental conditions causes deterioration of service properties.Understanding the aging behavior and mechanism is important not only for lifetime prediction,but also for material improvement an...Polymer aging under environmental conditions causes deterioration of service properties.Understanding the aging behavior and mechanism is important not only for lifetime prediction,but also for material improvement and development.Therefore,comprehensive characterization of polymer materials during aging is crucial.In this review,various analytical methods for characterization of chemical changes,physical changes and service properties are introduced.Based on that,methods for stabilization evaluation and lifetime prediction,especially sensitive evaluation methods are reviewed.Chemical changes include molecular weight changes by chain scission and crosslinking,functional group changes on the surface and in the bulk,formation of free radicals,formation of small molecular species as the degradation products,and chemical distribution by heterogeneous aging and additives migration.Physical changes include crystallization changes (post-or chemi-crystallization)and morphology changes (cracking,debonding,etc.).Service property changes include deterioration of processability,mechanical properties,electrical properties and appearance.In the end,existing problems and future research perspective are proposed,including relationship between chemical/physical changes and service properties,introduction of modern mathematical and computer tools.展开更多
It is well known that the deformation and damage of reservoir colluvium landslides are often determined by the combined dynamics of reservoir water level change and rainfall.Based on the systematic analysis of the cha...It is well known that the deformation and damage of reservoir colluvium landslides are often determined by the combined dynamics of reservoir water level change and rainfall.Based on the systematic analysis of the change law of reservoir water level,rainfall and displacements of reservoir colluvium landslide,this paper proposes the compound hydrodynamic action of rainfall and reservoir water as the unload-load parameter,and the landslide displacement as the unload-load response parameter.Based on this,a physical prediction model of the compound hydrodynamic unload-load response ratio of reservoir colluvium landslide was established,and the quantitative relationship between the compound hydrodynamic unload-load response ratio and its stability evolution was in-depth analyzed and determined.On the basis of the above research,taking Shuping landslide,a typical hydrodynamic pressure landslide as an example,the unload-load response ratio model is used to systematically evaluate and predict the stability evolution law and the change trend of the landslide under compound hydrodynamic action.The prediction result shows that the variation law of the compound hydrodynamic unload-load response ratio is consistent with the dynamic evolution law of its stability.Therefore,the above studies show that the compound hydrodynamic unload-load response ratio parameter is an effective displacement dynamic evaluation parameter for reservoir colluvium landslides,so it can be used in the prediction of the reservoir colluvium landslides.展开更多
Deep high-energy rock masses are susceptible to dynamic and static disasters in underground caverns when stress waves superimpose on them. Scientifically evaluating the stability of surrounding rock mass under such co...Deep high-energy rock masses are susceptible to dynamic and static disasters in underground caverns when stress waves superimpose on them. Scientifically evaluating the stability of surrounding rock mass under such conditions is fundamental for predicting and preventing related hazards. This study combines laboratory dynamic disturbance tests with numerical simulations to analyze changes in the three-dimensional stress state of surrounding rock caused by stress waves. It was found that stress waves not only alter the magnitude of unit stresses but also cause rotation of the principal stress axes. Based on the failure approach index(FAI), a new dynamic response evaluation index for brittle surrounding rock—the Energy Hazard Index(FAI_(E)) is proposed from an energy perspective. This index can derive functional expressions based on different strength criteria, offering good extensibility. Using the Mohr-Coulomb strength criterion as an example, the specific functional expression of FAI_(E) is provided. Comparison with experimental results confirms that the evaluation outcomes align with the dynamic response characteristics of surrounding rock mass, simultaneously considering both tensile and shear failure modes. Parameter sensitivity tests demonstrate the applicability of the index under complex conditions. Furthermore, the relationship between FAIE and commonly used dynamic disturbance evaluation parameters—such as Peak Particle Velocity(PPV)—has been examined, demonstrating that FAIE provides a more accurate and direct assessment of stability. Finally, a rapid engineering application method for FAIE is presented. The research findings hold significant importance for future stability evaluation and support design of surrounding rock in deep underground engineering projects.展开更多
A laser technique based scanning system was employed to make a comprehensive scanning through borehole forunmapped cavity under open pit bench,then the three-dimensional data will be obtained,and these data were used ...A laser technique based scanning system was employed to make a comprehensive scanning through borehole forunmapped cavity under open pit bench,then the three-dimensional data will be obtained,and these data were used for theoreticalanalysis and numerical simulation to analyze the stability of cap rock.Acoustic emission techniques were also adopted to carry outlong term real time rupture monitoring in cap rock.Therefore,a complete safety evaluation system for the cap rock was establishedto ensure safe operation of subsequent blasting processes.The ideal way of eliminating collapse hazard of such cavity is cap rockcaving through deep-hole blasting,thus,two deep-hole blasting schemes named as vertical deep-hole blasting scheme and one-timeraise driving integrated with deep-hole bench blasting scheme were proposed.The vertical deep-hole blasting scheme has moreexplosive consumption,but the relatively simple blasting net work structure can greatly reduce workloads.However,the one-timeraise driving integrated with deep-hole bench blasting scheme can obviously reduce explosive consumption,but the higher technicalrequirements on drilling,explosive charging and blasting network will increase workloads.展开更多
Yima Coal Corporation is considering to adopt highwall mining method withauger machine to recover coal from north surface pit that has reached final highwall position. Themajor geomechanical issues associated with aug...Yima Coal Corporation is considering to adopt highwall mining method withauger machine to recover coal from north surface pit that has reached final highwall position. Themajor geomechanical issues associated with auger mining are highwall and pillar stability. Based onthe field investigation and laboratory test results of mechanical parameters, numerical modeling iscarried out to assess the stability of highwall and pillar. Field measurements of highwalldeformation have been used to validate and ensure the confidence for the development of realisticmodels. The results of numerical modeling show that the mining method is feasible for mining theseam of 10 m thickness in north surface coal mine.展开更多
The optimum design of the highway excavation slope angle is one of the most important problems to the highway construction and to the slope improvement. The Dawu Section of Jingzhu (Beijing Zhuhai) Highway is taken a...The optimum design of the highway excavation slope angle is one of the most important problems to the highway construction and to the slope improvement. The Dawu Section of Jingzhu (Beijing Zhuhai) Highway is taken as an example to illustrate the study method for excavation slope angle design. The analysis of the engineering condition from different angles with different factors shows that the stability of the slope is calculated by using residual pushing force and the Sarma method. Then the sensitive analysis of the slope stability is conducted by using residual pushing force method. Finally, the optimum angle of design is presented on the precondition of ensuring the whole stability of slope and the economic reasonability. The study results show that the most sensitive factors are the shear strength parameter and the seismic force, and that the optimum excavation slope angle is 60°.展开更多
Buoy is the structure which is floated on sea surface in order to indicate the presenting obstacle such as reef and shallow sea and to show the direction of sea route to ship during sailing. Generally, the conventiona...Buoy is the structure which is floated on sea surface in order to indicate the presenting obstacle such as reef and shallow sea and to show the direction of sea route to ship during sailing. Generally, the conventional material of buoy is steel and it has some problems. Firstly this steel light buoy has safety risk in case of collision between ship and steel buoy. Secondly steel buoy revealed high corrosion environment of salted water and oxide and corrosion of steel can lead to marine pollution. Thirdly it needs too much maintain cost because of its heavy weight. In this study, in order to overcome these problems we changed the buoy material from conventional steel body to polyethylene body. Polymer buoy body was designed with module type part and it can reduce total weight up to 43.12%. To evaluate the strength of that part, the structure analysis simulation was carried out with respect to stress, displacement, and strain. Maximum stress was 1.667 × 107 N/m2 and it was 25% of yielding stress of base material. Maximum displacement and strain were 3.164 mm and 0.00433353 and they are too small value and in safe range with comparing to total length of body. The stability of polymer buoy body was compared with conventional buoy with respect to center of gravity, center of buoyancy, metacenter, oscillation period, and tilt angle by wind, tidal current, and wave. Every value was improved comparing conventional one and we can get more stable buoy. Therefore the new polymer buoy body could prove its safety and stability.展开更多
The distribution of Coulomb failure stress （CFS） change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated...The distribution of Coulomb failure stress （CFS） change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated. Comparing the CFSs before and after the slope excavation （stress loading and unloading processes）, the dangerous internal zone and the most likely failure external area are attained. Given the shear cracks on the top surface while tensile stress or cracks along the toe of the slope, we analyze the high cutting-angle steep slope in Kaixian county of the Three Gorges Reservoir region. We bring forward that the peak value of CFS after excavation can reach to the order of 0.1 MPa, which is greatly higher than that of before. Our preliminary results are useful for optimizing the reinforcement structure during the steep slope stabilization engineering.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42377191,42072300)“The 14th Five Year Plan”Hubei Provincial advantaged characteristic disciplines(groups)project of Wuhan University of Science and Technology(Grant No.2023A0303).
文摘The stability of the tunnel portal slope is crucial for ensuring safe tunnel construction.Thus,a sound stability evaluation is of significance.Given the unique geological characteristics of tunnel portal slopes,it is necessary to establish a specific evaluation indicator system that differs from those used for ordinary slopes.Based on the unascertained measure method,uncertainties in the indicator are addressed by introducing the left and right half cloud asymmetric cloud model to optimize the linear membership function.The subjectivity of confidence criterion level identification is also improved by using the Euclidean distance method.Thus,a stability evaluation model for the tunnel portal slope is established based on the improved unascertained measure method.Finally,using the collected tunnel portal slope data,the results of four evaluation methods are compared with the safety factor levels.The evaluation methods include the traditional unascertained measure method,the method improved by using the left and right half cloud asymmetric cloud model,the method improved by using the Euclidean distance method,and the method improved by using both the left and right half cloud asymmetric cloud model and the Euclidean distance method.The results show that the accuracy rates of these four methods are 50%,55%,85%,and 90%,respectively.Among them,the joint improvement method has the slightest deviation,with only one level,while the other three methods had deviations of two levels.This result verifies the stability and effectiveness of the joint improvement method,providing a reference for tunnel portal slope stability evaluation.
基金supported by the National Natural Science Foundation of China(Grant Nos.42307220 and 42090055)the Postdoctoral Research Project Funding of Shaanxi Province(Grant No.2023BSHEDZZ210).
文摘Deep-seated toppling in the upper reaches of the Lancang River,southwest China involves deformations exceeding 100 m in depth.The slope deformation is initiated by river downcutting and evolves distinctive characteristics with a depth of river incision.In this study,we propose a system for evaluating the stability of deep-seated toppled slopes in different evolutionary stages.This system contains identification criteria for each evolutionary stage and provides the corresponding stability evaluation methods.Based on the mechanical and kinematic analysis of slope blocks,the specific stage of slope movement can be identified in the field through outcrop mapping,in situ tests,surface displacement monitoring,and adit and borehole explorations.The stability evaluation methods are established based on the limiting equilibrium theory and the strain compatibility between the undisturbed zone and the toppled zone.Finally,several sample slopes in different evolution stages have been investigated to verify the applicability and accuracy of the proposed stability evaluation system.The results indicate that intense tectonic activity and rapid river incision lead to a maximum principal stress ratio exceeding 10 near the slope surface,thus triggering widespread toppling deformations along the river valley.When considering the losses of joint cohesion during the further rotation process,the safety factor of the slope drops by 7%e28%.The self-stabilization of toppling deformation can be recognized by the layer symmetry configuration after the free rotation of the deflected layers.Intensely toppled rock blocks mainly suffer sliding failures beyond the layer symmetry condition.The factor of safety of the K73 rockslide decreased from 1.17 to 0.87 by considering the development of the potential sliding surface and the toesaturated zone.
基金financially supported by the fund from the KeyArea Research and Development Program of Guangdong Province,China(2020B020223004)the Innovation Team Project in Guangdong Provincial Department of Education(2017KCXTD018)the Guangzhou Science and Technology Plan Projects,China(201704020190,201805010008 and 201904010135)。
文摘Real-time quantitative PCR(qPCR)is a reliable and widely used technique for analyzing the expression profiles of target genes in different species,and reference genes with stable expressions have been introduced for the normalization of the data.Therefore,stability evaluation should be considered as the initial step for qPCR experiments.The fall armyworm Spodoptera frugiperda(J.E.Smith)(Lepidoptera:Noctuidae)is a polyphagous pest that consumes many plant species and seriously threatens corn production around the world.However,no studies thus far have examined the stability of reference genes in this pest.In this study,the expression profiles of the eight candidate reference genes of Actin,elongation factor 1 alpha(EF1α),elongation factor 2(EF2),glyceraldehyde-3-phosphate dehydrogenase(GAPDH),ribosomal protein L3(RPL3),ribosomal protein L13(RPL13),alpha-tubulin(α-TUB),and beta-1-tubulin(β-1-TUB)were obtained from S.frugiperda in different samples and the stability was evaluated byΔCt,BestKeeper,geNorm,NormFinder,and RefFinder methods.The results of pairwise variation(V)calculated by GeNorm indicated two reference genes could be selected for normalization.Therefore,the combinations of the most stable reference genes for different experimental conditions of S.frugiperda were shown as follows:EF2 and RPL13 for developmental stages,RPL3 andβ-1-TUB for larval tissue samples,EF2 and EF1αfor the larval samples treated with different temperatures,RPL3 and EF1αfor the larval samples under starvation stress,and RPL13 and EF1αfor all the samples.Our results lay the foundation for the normalization of qPCR analyses in S.frugiperda and could help guarantee the accuracy of subsequent research.
基金supported by the Chongqing Administration of Science and Technology(Grants No.cstc2021jxjl20008,cstc2020jcyj-msxm X1068)the Chongqing Administration of Planning and Natural Resources(Grant No.KJ-2019018)。
文摘Rock slide is one of the common geohazard in the Three Gorges Reservoir area, and it affects the shipping of the Yangtze River and the safety of people living on the banks. In order to investigate the internal fracturing mechanism of rock mass, distributed microseismic monitoring network was arranged with 15 three component geophones(3C geophones), deployed at borehole and out of the sliding mass in the unstable Dulong slope. Stein Unbiased Risk Estimation(SURE) method was used to noise suppression for the microseismic record, and decomposition parameters of the Continuous Wavelet Transform(CWT) were determined with maximum energy of correlation coefficient(MECC) method. The signal-to-noise ratio was tripled after the process, and source parameters are obtained with full waveform inversion. The rupture volume model was counted by the irregular grid statistics with the events’ density. It shows that the rock slide is of a small scale and composed of a single block. Moreover, the relationship among microseismicity, displacement and rainfall were discussed in the paper. The deformation rate was dramatically changed in the period of intensive events. There is a good consistency especially in the rainfall period. Although there is a time delay, continuous rainfall is more likely to cause the increase of microseismic events. The results show that the Dulong slope is a shallow rock slide in the state of creep deformation, and the rupture mechanism of the rock mass is left-lateral normal fault with shear failure. The research provides more key information for the early warning and prevention of rock slides and helps to reduce the risk of geohazards.
文摘One of the main issues in tree stability evaluations is the scheduling of adequate monitoring programs. Generally, after a tree analysis, an arborist indicates the required maintenance operations and the timing for periodical inspection. Field conditions, tree species and biomechanical defects influence the plan. Three old trees （Populus spp. and Celtis australis） located within Golf Club Verona （Sommacampagna, Italy） were monitored periodically from 2010 to present. In addition to visual assessment, authors used sonic tomography to evaluate development of internal defects and planning the maintenance. The aim of this work is to identify a methodology for observing significant difference in tomograms, in order to understand the appropriate interval between instrumental analyses.
文摘A scientific and rational evaluation on road-region ecosystem stability is the premise to properly deal with the relationship between highway constructing and ecological environment protecting to a sustainable development. Based on the connotative meaning and the procedure of evaluation on road-region ecosystem stability, this paper studied the principles and the method on determining the evaluation index system on road-region ecosystem stability. It put forward an index system for assessing road-region ecosystem stability as a reference. On the basis of detailed analyze of the multidimensional space of road-region ecosystem, a new multi-objective comprehensive evaluation method for road-region ecosystem stability is presented and a calculation tormula for multi-objective comprehensive level of road-region ecosystem stability. This method was used to evaluate road-region ecosystem stability of Lin-Chang highway. This method possessed definite theoretical value and reliability in practice.
基金supported by the National Natural Science Foundation of China(Grant No.42177164)the Distinguished Youth Science Foundation of Hunan Province of China(Grant No.2022JJ10073)the Outstanding Youth Project of Hunan Provincial Department of Education,China(Grant No.23B0008).
文摘In underground mining,especially in entry-type excavations,the instability of surrounding rock structures can lead to incalculable losses.As a crucial tool for stability analysis in entry-type excavations,the critical span graph must be updated to meet more stringent engineering requirements.Given this,this study introduces the support vector machine(SVM),along with multiple ensemble(bagging,adaptive boosting,and stacking)and optimization(Harris hawks optimization(HHO),cuckoo search(CS))techniques,to overcome the limitations of the traditional methods.The analysis indicates that the hybrid model combining SVM,bagging,and CS strategies has a good prediction performance,and its test accuracy reaches 0.86.Furthermore,the partition scheme of the critical span graph is adjusted based on the CS-BSVM model and 399 cases.Compared with previous empirical or semi-empirical methods,the new model overcomes the interference of subjective factors and possesses higher interpretability.Since relying solely on one technology cannot ensure prediction credibility,this study further introduces genetic programming(GP)and kriging interpolation techniques.The explicit expressions derived through GP can offer the stability probability value,and the kriging technique can provide interpolated definitions for two new subclasses.Finally,a prediction platform is developed based on the above three approaches,which can rapidly provide engineering feedback.
基金supported by the National Natural Science Foundation of China(Nos.42090054,42377192)the Scientific Research Project of Power China Huadong Engineering Corporation Limited(No.KY2022-KC-02-02)the Natural Science Foundation of Hubei Province,China(No.2022CFA002)。
文摘0 INTRODUCTION Submarine slope slides refer to a geological process occurring on submarine slopes or continental margin slopes,where a large amount of sediment or rock layers on the slope lose stability and slide downward along the sliding surface(Kamran et al.,2023;Tong et al.,2023;Hampton et al.,1996).
基金Project(2019QZKK0905)supported by the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program,ChinaProject(41901074)supported by the National Natural Science Foundation of China+2 种基金Project(2020A1515010745)supported by the Natural Science Foundation of Guangdong Province,ChinaProject(SKLFSE201810)supported by the Open Fund of the State Key Laboratory of Frozen Soil Engineering,ChinaProject(2019MS119)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Embankment stability is the primary problem for the expressway construction in permafrost regions.The proposed Qinghai-Tibet Expressway(QTE)is planned to construct along the Qinghai-Tibet Project Corridor.Confronted with harsh environmental condition and intense heat exchange between earth and atmosphere,it is necessary to predict and evaluate the stability of the proposed QTE.In this study,the factors affecting the embankment stability are analyzed firstly.And then,a scheme for the stability evaluation of the embankment is established.Finally,the evaluation scheme is used for the pre-evaluation of the stability for the proposed QTE with different geothermal regulation measures(GRMs).The results indicate that the influencing factors include climatic environment,permafrost property,engineering condition and geological condition,and among them,engineering condition and permafrost property are the main influence factors for embankment stability.The stability of the proposed QTE varies greatly in the different geomorphological regions.The application effect and contribution to embankment stability of the existing GRMs are different,and using GRMs cannot completely overcome the influence of various factors on expressway stability.In the construction process,different GRMs should be adopted depending on the geomorphological environment where the embankment is located to ensure the embankment stability.
文摘Slope is the carrier of geological disasters. Local slope deformation and destruction are the beginning of the formation of collapse, landslide and debris flow. For the evaluation of slope stability, it is the purpose of this evaluation to distinguish unstable, unstable, basically stable and stable slopes in the town area of Taoyuan Township. Combined with field ground investigation and remote sensing images, the data of soil thickness, stratum lithology, terrain slope, slope structure type, regional rainfall, geological structure, human activities and slope height of each slope are collected, and the slope stability evaluation is carried out for rocky slopes and soil slopes. The expert consultation method is used to assign weight and grade assignment to each factor, and the fuzzy comprehensive evaluation method is used to evaluate the stability of 95 natural slopes divided by Taoyuan Township. Based on the evaluation results, the slope stability zoning map of the study area is drawn, and the regional slope stability distribution law is summarized. The evaluation results can provide basic information for local geological disaster management, urban planning, road planning, etc.
基金supported by the CNPC Major Science and Technology Project“Research and Application of Key Technologies in Geology and Gas Reservoir Engineering of Underground Gas Storage”(No.:2015E-400201).
文摘Salt-cavern underground gas storage is technically faced with non-uniform distribution of stratified salt rocks,complex solution mining mechanism,difficult control of solution mining process,less operation safety and stability of caverns and difficult reconstruction and utilization of old caverns.In view of these technical difficulties,the design concept was fully updated based on the design experience and field practice of Jintan gas storage in Jiangsu,for purpose of maximizing salt layer utilization ratio,improving solution mining efficiency,shortening construction time and ensuring cavity safety.Based on the updated design concept,five series of key technologies were proposed in site evaluation,cavern design and control,stability assessment and storage capacity parameter design,old cavern screening and utilization,and gas storage operation and monitoring.The following results were obtained from the actual application of these key technologies to the Jintan gas storage.First,the actual drilling coincidence rate of geological program is high.Second,the cavern is morphologically coincident with the design.Third,the cavern deformation retract rate is in line with the stability evaluation result.Fourth,old caverns are successfully reconstructed and utilized.Fifth,the arrangement of the monitoring network ensures the operation safety of salt-cavern underground gas storage and makes an important contribution to the peak shaving and supply guarantee of natural gas in the Yangtze River Delta region.In conclusion,the research results provide guidance for the design and engineering implementation of salt-cavern underground gas storage construction program,as well as a theoretical and technical support for the construction of similar gas storages.
基金Supported by the National Natural Science Foundation of China(50874042)
文摘According to the rock engineering property and stability of high-steep open-pitslopes, various factors were collected on the basis of rock engineering system (RSE) theory,and the interaction matrix of stability evaluation was established.Then, the stabilityevaluation index (S_p) of the slope was put forward.Ranges of the S_p value and the correspondingstable state were given on the basis of thirty-six samples.It is found that the followingrelationships exist: unstable (easy landslide): S_p<-0.20; mid-stable (may be landslide):-0.20<S_p<0.63; stable (no landslide): S_p>0.63.Finally, the stability evaluation indexwas applied on the high-steep open-pit slope of one mine.Analysis results and monitoringdata indicate that the index meets the necessity of the property of slope engineering, and ithas an important engineering purpose for landslide forecasting of high-steep slopes.
基金financially supported by the 2023 High-level Scientific Research Foundation for the Introduction of Talent of Hefei Normal University (No.2023rcjj08)the Research Project of Hefei Normal University (No.2023QN06).
文摘Polymer aging under environmental conditions causes deterioration of service properties.Understanding the aging behavior and mechanism is important not only for lifetime prediction,but also for material improvement and development.Therefore,comprehensive characterization of polymer materials during aging is crucial.In this review,various analytical methods for characterization of chemical changes,physical changes and service properties are introduced.Based on that,methods for stabilization evaluation and lifetime prediction,especially sensitive evaluation methods are reviewed.Chemical changes include molecular weight changes by chain scission and crosslinking,functional group changes on the surface and in the bulk,formation of free radicals,formation of small molecular species as the degradation products,and chemical distribution by heterogeneous aging and additives migration.Physical changes include crystallization changes (post-or chemi-crystallization)and morphology changes (cracking,debonding,etc.).Service property changes include deterioration of processability,mechanical properties,electrical properties and appearance.In the end,existing problems and future research perspective are proposed,including relationship between chemical/physical changes and service properties,introduction of modern mathematical and computer tools.
基金supported by the National Natural Science Foundation of China(No.41372297)the Natural Science Foundation of Shandong Province(No.ZR2020KE004)+1 种基金the Open Fund of Key Laboratory of Geological Safety of Coastal Urban Underground Space,Ministry of Natural Resources(No.BHKF2021Y05)the Qingdao Postdoctoral Applied Research Project and the Open Foundation of Geo-Engineering Surveying Institute of Qingdao(No.2019-QDDZYKF02).
文摘It is well known that the deformation and damage of reservoir colluvium landslides are often determined by the combined dynamics of reservoir water level change and rainfall.Based on the systematic analysis of the change law of reservoir water level,rainfall and displacements of reservoir colluvium landslide,this paper proposes the compound hydrodynamic action of rainfall and reservoir water as the unload-load parameter,and the landslide displacement as the unload-load response parameter.Based on this,a physical prediction model of the compound hydrodynamic unload-load response ratio of reservoir colluvium landslide was established,and the quantitative relationship between the compound hydrodynamic unload-load response ratio and its stability evolution was in-depth analyzed and determined.On the basis of the above research,taking Shuping landslide,a typical hydrodynamic pressure landslide as an example,the unload-load response ratio model is used to systematically evaluate and predict the stability evolution law and the change trend of the landslide under compound hydrodynamic action.The prediction result shows that the variation law of the compound hydrodynamic unload-load response ratio is consistent with the dynamic evolution law of its stability.Therefore,the above studies show that the compound hydrodynamic unload-load response ratio parameter is an effective displacement dynamic evaluation parameter for reservoir colluvium landslides,so it can be used in the prediction of the reservoir colluvium landslides.
基金supported by the National Natural Science Foundation of China (Grant No.52279116,Grant No.52109142)the Key projects of the Yalong River Joint Fund of the National Natural Science Foundation of China (Grant No.U1865203)。
文摘Deep high-energy rock masses are susceptible to dynamic and static disasters in underground caverns when stress waves superimpose on them. Scientifically evaluating the stability of surrounding rock mass under such conditions is fundamental for predicting and preventing related hazards. This study combines laboratory dynamic disturbance tests with numerical simulations to analyze changes in the three-dimensional stress state of surrounding rock caused by stress waves. It was found that stress waves not only alter the magnitude of unit stresses but also cause rotation of the principal stress axes. Based on the failure approach index(FAI), a new dynamic response evaluation index for brittle surrounding rock—the Energy Hazard Index(FAI_(E)) is proposed from an energy perspective. This index can derive functional expressions based on different strength criteria, offering good extensibility. Using the Mohr-Coulomb strength criterion as an example, the specific functional expression of FAI_(E) is provided. Comparison with experimental results confirms that the evaluation outcomes align with the dynamic response characteristics of surrounding rock mass, simultaneously considering both tensile and shear failure modes. Parameter sensitivity tests demonstrate the applicability of the index under complex conditions. Furthermore, the relationship between FAIE and commonly used dynamic disturbance evaluation parameters—such as Peak Particle Velocity(PPV)—has been examined, demonstrating that FAIE provides a more accurate and direct assessment of stability. Finally, a rapid engineering application method for FAIE is presented. The research findings hold significant importance for future stability evaluation and support design of surrounding rock in deep underground engineering projects.
基金Projects(51204206,41272304,41372278) supported by the National Natural Science Foundation of China
文摘A laser technique based scanning system was employed to make a comprehensive scanning through borehole forunmapped cavity under open pit bench,then the three-dimensional data will be obtained,and these data were used for theoreticalanalysis and numerical simulation to analyze the stability of cap rock.Acoustic emission techniques were also adopted to carry outlong term real time rupture monitoring in cap rock.Therefore,a complete safety evaluation system for the cap rock was establishedto ensure safe operation of subsequent blasting processes.The ideal way of eliminating collapse hazard of such cavity is cap rockcaving through deep-hole blasting,thus,two deep-hole blasting schemes named as vertical deep-hole blasting scheme and one-timeraise driving integrated with deep-hole bench blasting scheme were proposed.The vertical deep-hole blasting scheme has moreexplosive consumption,but the relatively simple blasting net work structure can greatly reduce workloads.However,the one-timeraise driving integrated with deep-hole bench blasting scheme can obviously reduce explosive consumption,but the higher technicalrequirements on drilling,explosive charging and blasting network will increase workloads.
文摘Yima Coal Corporation is considering to adopt highwall mining method withauger machine to recover coal from north surface pit that has reached final highwall position. Themajor geomechanical issues associated with auger mining are highwall and pillar stability. Based onthe field investigation and laboratory test results of mechanical parameters, numerical modeling iscarried out to assess the stability of highwall and pillar. Field measurements of highwalldeformation have been used to validate and ensure the confidence for the development of realisticmodels. The results of numerical modeling show that the mining method is feasible for mining theseam of 10 m thickness in north surface coal mine.
基金theNationalNaturalScienceFoundationofChina (No .40 0 72 0 85 )
文摘The optimum design of the highway excavation slope angle is one of the most important problems to the highway construction and to the slope improvement. The Dawu Section of Jingzhu (Beijing Zhuhai) Highway is taken as an example to illustrate the study method for excavation slope angle design. The analysis of the engineering condition from different angles with different factors shows that the stability of the slope is calculated by using residual pushing force and the Sarma method. Then the sensitive analysis of the slope stability is conducted by using residual pushing force method. Finally, the optimum angle of design is presented on the precondition of ensuring the whole stability of slope and the economic reasonability. The study results show that the most sensitive factors are the shear strength parameter and the seismic force, and that the optimum excavation slope angle is 60°.
文摘Buoy is the structure which is floated on sea surface in order to indicate the presenting obstacle such as reef and shallow sea and to show the direction of sea route to ship during sailing. Generally, the conventional material of buoy is steel and it has some problems. Firstly this steel light buoy has safety risk in case of collision between ship and steel buoy. Secondly steel buoy revealed high corrosion environment of salted water and oxide and corrosion of steel can lead to marine pollution. Thirdly it needs too much maintain cost because of its heavy weight. In this study, in order to overcome these problems we changed the buoy material from conventional steel body to polyethylene body. Polymer buoy body was designed with module type part and it can reduce total weight up to 43.12%. To evaluate the strength of that part, the structure analysis simulation was carried out with respect to stress, displacement, and strain. Maximum stress was 1.667 × 107 N/m2 and it was 25% of yielding stress of base material. Maximum displacement and strain were 3.164 mm and 0.00433353 and they are too small value and in safe range with comparing to total length of body. The stability of polymer buoy body was compared with conventional buoy with respect to center of gravity, center of buoyancy, metacenter, oscillation period, and tilt angle by wind, tidal current, and wave. Every value was improved comparing conventional one and we can get more stable buoy. Therefore the new polymer buoy body could prove its safety and stability.
基金supported by Sinoprob-Deep Exploration Program in China sponsored by Ministry of Land and Resources of the People’s Republic of China (No.0819011A90)National Natural Science Foundation of China (No.D0408/4097409)
文摘The distribution of Coulomb failure stress （CFS） change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated. Comparing the CFSs before and after the slope excavation （stress loading and unloading processes）, the dangerous internal zone and the most likely failure external area are attained. Given the shear cracks on the top surface while tensile stress or cracks along the toe of the slope, we analyze the high cutting-angle steep slope in Kaixian county of the Three Gorges Reservoir region. We bring forward that the peak value of CFS after excavation can reach to the order of 0.1 MPa, which is greatly higher than that of before. Our preliminary results are useful for optimizing the reinforcement structure during the steep slope stabilization engineering.
