The cement-fly ash composite expansive stable grout was prepared to deal with the problems of poor stability and volume shrinkage of ordinary cement grout,and the effects of fly ash ratio and water-binder ratio on the...The cement-fly ash composite expansive stable grout was prepared to deal with the problems of poor stability and volume shrinkage of ordinary cement grout,and the effects of fly ash ratio and water-binder ratio on the properties of the grout and its consolidation were analyzed.In addition,the mineral composition and microstructural characteristics of grout consolidation with different mixing ratios were investigated.The experimental results indicate that fly ash and the increase of water-binder ratio reduce the strength of the grout consolidation,and increase the fluidity,bleeding rate,and setting time of the composite grout.However,the magnitude of the fly ash-induced strength reduction decreases with time.And the effect of fly ash on the setting time and compressive strength becomes more significant with the water-binder ratio.The later expansion performance of grout consolidation(after 7-42 d)is improved by fly ash.But the expansibility of consolidation with fly ash decreases at the early curing stage,and the reduction amplitude of expansion rate is smaller and the reduction age is shorter with the water-binder ratio increase.Fly ash improves the corrosion resistance performance of grout consolidation,and the corrosion resistance coefficient rises first and then falls with the fly ash ratio.And for 0.6:1 water-binder ratio,the corrosion resistance coefficient of the samples mixed with fly ash are greater than 100%.XRD and SEM show that fly ash inhibited the formation of ettringite in the early stage,which is unfavorable to the expansion of the slurry,and with the increase of age,this effect gradually weakened.展开更多
The fractured surrounding rocks of roadways pose major challenges to safe mining.Grouting has often been used to reinforce the surrounding rocks to mitigate the safety risks associated with fractured rocks.The aim of ...The fractured surrounding rocks of roadways pose major challenges to safe mining.Grouting has often been used to reinforce the surrounding rocks to mitigate the safety risks associated with fractured rocks.The aim of this study is to develop highly efficient composite ultrafine cement(CUC)grouts to reinforce the roadway in fractured surrounding rocks.The materials used are ultrafine cement(UC),ultrafine fly ash(UF),ultrafine slag(US),and additives(superplasticizer[SUP],aluminate ultrafine expansion agent[AUA],gypsum,and retarder).The fluidity,bleeding,shrinkage,setting time,chemical composition,microstructure,degree of hydration,and mechanical property of grouting materials were evaluated in this study.Also,a suitable and effective CUC grout mixture was used to reinforce the roadway in the fractured surrounding rock.The results have shown that the addition of UF and US reduces the plastic viscosity of CUC,and the best fluidity can be obtained by adding 40%UF and 10%US.Since UC and UF particles are small,the pozzolanic effect of UF promotes the hydration reaction,which is conductive to the stability of CUC grouts.In addition,fine particles of UC,UF,and US can effectively fill the pores,while the volumetric expansion of AUA and gypsum decreases the pores and thus affects the microstructure of the solidified grout.The compressive test results have shown that the addition of specific amounts of UF and US can ameliorate the mechanical properties of CUC grouts.Finally,the CUC22‐8 grout was used to reinforce the No.20322 belt roadway.The results of numerical simulation and field monitoring have indicated that grouting can efficaciously reinforce the surrounding rock of the roadway.In this research,high‐performance CUC grouts were developed for surrounding rock reinforcement of underground engineering by utilizing UC and some additives.展开更多
Grouting has been the most effective approach to mitigate water inrush disasters in underground engineering due to its ability to plug groundwater and enhance rock strength.Nevertheless,there is a lack of potent numer...Grouting has been the most effective approach to mitigate water inrush disasters in underground engineering due to its ability to plug groundwater and enhance rock strength.Nevertheless,there is a lack of potent numerical tools for assessing the grouting effectiveness in water-rich fractured strata.In this study,the hydro-mechanical coupled discontinuous deformation analysis(HM-DDA)is inaugurally extended to simulate the grouting process in a water-rich discrete fracture network(DFN),including the slurry migration,fracture dilation,water plugging in a seepage field,and joint reinforcement after coagulation.To validate the capabilities of the developed method,several numerical examples are conducted incorporating the Newtonian fluid and Bingham slurry.The simulation results closely align with the analytical solutions.Additionally,a set of compression tests is conducted on the fresh and grouted rock specimens to verify the reinforcement method and calibrate the rational properties of reinforced joints.An engineering-scale model based on a real water inrush case of the Yonglian tunnel in a water-rich fractured zone has been established.The model demonstrates the effectiveness of grouting reinforcement in mitigating water inrush disaster.The results indicate that increased grouting pressure greatly affects the regulation of water outflow from the tunnel face and the prevention of rock detachment face after excavation.展开更多
The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride so...The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride solutions of specific concentrations with different test ages.Hardened properties of the mixes were assessed in terms of weight loss and compressive strength.X-ray diffraction(XRD)and scanning electron microscopy(SEM)of mixes were performed to analysis the phase evolution and microstructure.The results demonstrated that the introduction of nano-SiO_(2) emulsion significantly decreased the compressive strength loss and calcium hydroxide(CH)crystal content of hydration production,and then enhanced the resistance of cement-based grouting materials to chloride ion penetration.This improvement derives from the filling and pozzolanic effects of nano-SiO_(2) particles,which were incorporated via an emulsion and attributed to a well dispersion in grouting matrix.展开更多
The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,h...The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.展开更多
Curtain grouting projects are characterized by their large scale and complexity,presenting significant challenges for real-time prediction of grout penetration using traditional methods.This study introduces an intell...Curtain grouting projects are characterized by their large scale and complexity,presenting significant challenges for real-time prediction of grout penetration using traditional methods.This study introduces an intelligent prediction method for grouting in fractured rock masses based on three core principles:integration of multi-source input features,fracture voxel modeling,and shortest path in sequential grouting.Three categories of data(geological structure data,grouting environmental data,and grouting operation data in the concept of a grouting geological model)are integrated and served as multi-source structured data in the intelligent prediction of grouting.A voxelization model quantifies the spatial characteristics of fractures,with voxel size optimized for capturing grouting paths.A shortest path algorithm based on a hierarchical solution is then developed to calculate grout penetration distances in the process of sequential grouting.A complete analysis framework is established,from the voxelization of the fracture network model to precise voxel classification,ultimately achieving an accurate prediction of grout penetration.The method demonstrates excellent performance on the test set,with validation against numerical methods in single-fracture and sequential grouting scenarios confirming its accuracy and prediction efficiency as hundreds of times faster than numerical methods.Application to the Dongzhuang hydraulic project’s grouting test area further validates its effectiveness in multi-hole grouting scenarios.展开更多
Due to the invisibility and complexity of the underground spaces,monitoring the propagation and filling characteristics of the grouting slurry post the water–sand mixture inrush in metal mines is challenging,which co...Due to the invisibility and complexity of the underground spaces,monitoring the propagation and filling characteristics of the grouting slurry post the water–sand mixture inrush in metal mines is challenging,which complicates engineering treatment.This research investigated the propagation law of cement-sodium silicate slurry under flowing water conditions within the caving mass of a metal mine.First,based on borehole packer test results and borehole TV images,the fractured strata before grouting were classified into four types:cavity,hidden,fissure,and complete.Second,an orthogonal experimental design was employed to evaluate the impact of four key factors—stratigraphic fragmentation,water flow rate,grouting flow rate,and water-cement ratio—on the efficacy of grouting within a caving mass at the site.The results indicate that the factors influencing grouting efficacy are ranked in the following order of importance:stratigraphic fragmentation>water flow rate>water–cement ratio>grouting flow rate.Ultimately,five propagation filling modes—pure slurry,big crack,small crack,small karst pore,and pore penetration—were identified by examining the propagation filling characteristics of slurry in rock samples,incorporating microscopic material structure analysis through scanning electron microscopy and energy spectrum analysis.The findings of this study provide valuable insights into selecting engineering treatment parameters and methodologies,serving as a reference for preventing and controlling water–sand mixture inrush in metal mines,thereby enhancing treatment efficacy and ensuring grouting success.展开更多
Concrete is one of the most important elements in building construction.However,concrete used in construction is susceptible to damage due to corrosion.The influence of corrosive substances causes changes in the reinf...Concrete is one of the most important elements in building construction.However,concrete used in construction is susceptible to damage due to corrosion.The influence of corrosive substances causes changes in the reinforcing steel and affects the strength of the structure.The repair method is one approach to overcome this problem.This research aims to determine the effect of grouting and jacketing repairs on corroded concrete.The concrete used has dimensions of 15 cm×15 cm×60 cm with planned corrosion variations of 50%,60%,and 70%.The test objects were tested using the Non-Destructive Testing(NDT)method using Ultrasonic Pulse Velocity(UPV).The test results show that the average speed of normal concrete is 5070 m/s,while the lowest average speed is 3070 m/s on the 70%planned corrosion test object.The test object was then given a load of 1600 kgf.At this stage,there is a decrease in speed and wave shape with the lowest average speed obtained at 2753 m/s.The repair method is an effort to restore concrete performance by using grouting and jacketing.Grouting is done by injecting mortar material into it.Jacketing involves adding thickness to the existing concrete layer with additional layers of concrete.After improvements were made,there was an improvement in the UPV test,with a peak speed value of 4910 m/s.Repairing concrete by filling cracks can improve concrete continuity and reduce waveform distortion,thereby increasing wave propagation speed.展开更多
Grouting is a widely applied technique for reinforcing fractured zones in deep soft rock tunnels.By infiltrating rock fissures,slurry materials enhance structural integrity and improve the overall stability of the sur...Grouting is a widely applied technique for reinforcing fractured zones in deep soft rock tunnels.By infiltrating rock fissures,slurry materials enhance structural integrity and improve the overall stability of the surrounding rock.The performance of grouting is primarily governed by the flow behavior and diffusion extent of the slurry.This review considers recent advances in the theory and methodology of slurry flow and diffusion in fractured rock.It examines commonly used grout materials,including cement-based,chemical,and composite formulations,each offering distinct advantages for specific geological conditions.Themechanisms of reinforcement vary significantly across materials,requiring tailored application strategies.The rheological properties of grouting slurries,particularly cement-based types,have been widely modeled using classical constitutive approaches.However,the influence of time-and space-dependent viscosity evolution on slurry behavior remains underexplored.Experimental studies have provided valuable insights into slurry diffusion,yet further research is needed to capture real-time behavior under multi-scale and multi-physics coupling conditions.Similarly,current numerical simulations are largely limited to twoand three-dimensional models of single-fracture flow.These models often neglect the complexity of fracture networks and geological heterogeneity,highlighting a need for more realistic and integrated simulation frameworks.Future research should focus on:(1)fine-scale modeling of slurry hydration and mechanical reinforcement processes;(2)cross-scale analysis of slurry flow under coupled thermal,hydraulic,andmechanical fields;and(3)development of realtime,three-dimensional dynamic simulation tools to capture the full grouting process.These efforts will strengthen the theoretical foundation and practical effectiveness of grouting in complex underground environments.展开更多
In the civil and mining industries,bolts are critical components of support systems,playing a vital role in ensuring their stability.Glass fibre reinforced polymer(GFRP)bolts are widely used because they are corrosion...In the civil and mining industries,bolts are critical components of support systems,playing a vital role in ensuring their stability.Glass fibre reinforced polymer(GFRP)bolts are widely used because they are corrosion-resistant and cost-effective.However,the damage mechanisms of GFRP bolts under blasting dynamic loads are still unclear,especially compared to metal bolts.This study investigates the cumulative damage of fully grouted GFRP bolts under blasting dynamic loads.The maximum axial stress at the tails of the bolts is defined as the damage variable,based on the failure characteristics of GFRP bolts.By combining this with Miner's cumulative damage theory,a comprehensive theoretical and numerical model is established to calculate cumulative damage.Field data collected from the Jinchuan No.3 Mining Area,including GFRP bolts parameters and blasting vibration data are used for further analysis of cumulative damage in fully grouted GFRP bolts.Results indicate that with an increasing number of blasts,axial stress increases in all parts of GFRP bolts.The tail exhibits the most significant rise,with stress extending deeper into the anchorage zone.Cumulative damage follows an exponential trend with the number of blasts,although the incremental damage per blast decelerates over time.Higher dynamic load intensities accelerate damage accumulation,leading to an exponential decline in the maximum loading cycles before failure.Additionally,stronger surrounding rock and grout mitigate damage accumulation,with the effect of surrounding rock strength being more pronounced than that of grout.In contrast,the maximum axial stress of metal bolts increases quickly to a certain point and then stabilizes.This shows a clear difference between GFRP and metal bolts.This study presents a new cumulative damage theory that underpins the design of GFRP bolt support systems under blasting conditions,identifies key damage factors,and suggests mitigation measures to enhance system stability.展开更多
Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were condu...Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were conducted,with varying pressures from 400 kPa to 800 kPa,to quantitatively evaluate the densification effect in unsaturated soils.The response of surrounding soil during compaction grouting was monitored.The changes in dry density and void ratio induced by compaction grouting were obtained by monitoring volumetric water content to determine compaction efficiency.In addition,a model was developed and validated to predict the effective compaction range.The results show that soil dry density increased rapidly during compaction grouting before being stabilized at a consistent level.As expected,it is positively correlated with grouting pressures(GPs)and negatively correlated with the distance from the injection point.At higher GPs,the difference in densification effect around the injection point after compaction grouting was significant.Interestingly,variations in ultimate dry density and peak earth pressures perpendicular to the injection direction exhibited axisymmetric behavior around the injection point when comparing the dry density and earth pressure results.Furthermore,soil densification resulted in a decrease in suction.However,no significant effect of GP on suction at different soil positions was observed.Moreover,compaction efficiency decreased with increasing distance from the injection point,showing a strong linear relationship.In addition,the model results for the effective compaction range were basically consistent with the extrapolated values from the experimental results.展开更多
The rapid development of urban rail transit has posed increasing construction and operational challenges for metro tunnels,often leading to structural damage.Grouting technology using cement-based materials is widely ...The rapid development of urban rail transit has posed increasing construction and operational challenges for metro tunnels,often leading to structural damage.Grouting technology using cement-based materials is widely applied to address issues such as seepage,leakage,and alignment correction in shield tunnels.This study investigates the additional stress induced by grouting in silty soil layers,using cement-based grouts with different water-to-cement ratios and polyurethane-modified cement-based materials.Results show that additional stress decreases with depth and is more influenced by horizontal distance from the grouting point.In staged grouting,the first injection phase contributes about 50%of the peak additional stress.A lower water-to-cement ratio(e.g.,0.6)increases additional stress but reduces grout flowability,while a higher ratio improves diffusion but increases the risk of grout loss.(≥1.0)The polyurethane-modified cement-based material enhances stress transfer performance,increasing peak additional stress by approximately 10%.These findings provide theoretical guidance for optimizing material selection and grouting design in metro tunnel repair within silty soil layers.展开更多
Groundwater inrush is a hazard that always occurs during underground mining.Grouting is one of the most effective processes to seal underground water inflow for hazard prevention.In this study,grouting experiments are...Groundwater inrush is a hazard that always occurs during underground mining.Grouting is one of the most effective processes to seal underground water inflow for hazard prevention.In this study,grouting experiments are conducted by using a visualized transparent single-fracture replica with plane roughness.Image processing and analysis are performed to investigate the thermo–hydro–mechanical coupling effect on the grouting diffusion under coal mine flowing water conditions.The results show that higher ambient temperature leads to shorter initial gel time of chemical grout and leads to a better relative sealing efficiency in the case of a lower flow rate.However,with a higher water flow rate,the relative sealing efficiency is gradually reduced under higher temperature conditions.The grouting pressure,the seepage pressure,and the temperature are measured.The results reveal that the seepage pressure shows a positive correlation with the grouting pressure,while the temperature change shows a negative correlation with the seepage pressure and the grouting pressure.The“equivalent grouting point offset”effect of grouting shows an eccentric elliptical diffusion with larger grouting distance and width under lower temperature conditions.展开更多
As the cost of grouting treatment for water control in coal roofs during underground coal mining continues to rise,coupled with the accumulation of industrial solid waste resulting from rapid economic development in C...As the cost of grouting treatment for water control in coal roofs during underground coal mining continues to rise,coupled with the accumulation of industrial solid waste resulting from rapid economic development in China,the ecological environment is facing severe challenges.To address these issues,this study,based on a high water-to-cement ratio,uses mine overburden(OB)and furnace bottom ash(FBA)as the primary raw materials,with sodium silicate as the modifier,to develop a new type of geopolymer grouting material with high stability and compressive strength for coal roof water control.Additionally,COMSOL software was used to numerically simulate the diffusion process of the grout slurry in fractures under dynamic water flow.The results indicate that,with a sodium silicate modulus of 1.5 and a dosage of 4%,the stability of the slurry increased by 26.2%,and the 28-day compressive strength improved by 130.98%.Numerical simulations further show that the diffusion process of the slurry is closely related to slurry viscosity,grouting pressure,and grouting time and that the diffusion pattern in the fractures is similar to that of ultra-fine cement slurry.This study provides a theoretical basis for coal mine roof grouting water control projects.展开更多
Grouting injection is a vital technique for addressing the challenges of high stress and significant deformation in the surrounding rock during deep mining operations,playing a crucial role in promoting green and low-...Grouting injection is a vital technique for addressing the challenges of high stress and significant deformation in the surrounding rock during deep mining operations,playing a crucial role in promoting green and low-carbon extraction methodologies.In this study,grouting reinforcement processes were examined by conducting grouting experiments on a fractured rock with varying negative pressures(0-100 kPa),followed by uniaxial compression testing of the grout-reinforced bodies.This investigation explored the diffusion patterns of grout under negative pressure and established a constitutive model of damage-bearing capacity for bodies reinforced by negative pressure grouting.It further studied the enhancement effect of negative pressure on the load-bearing capacity of the reinforced bodies and analyzed the instability mechanism of damage and failure in these bodies.The results indicated that the diffusion of grout under negative pressure is influenced by four types of forces,which alter the extent of grout diffusion within the fractured rock mass.Introducing a damage constitutive model that serially connects pore and framework elements characterizes the damage and failure behavior of groutreinforced bodies under different negative pressures.As the negative pressure increases,changes in porosity,water-to-cement ratio,and admixture quantity occur in the grout-reinforced specimens,with the strength mean curve showing a trend of first increasing and then decreasing,reaching a threshold at a negative pressure of 60 kPa.With increasing negative pressure,the negative pressure damage variable decreases and then increases,and the stronger the interfacial microelement connections caused by the negative pressure,the greater the bearing capacity,ultimately manifesting in different failure modes.展开更多
Grouting represents a reliable method for strengthening fractured rock masses and preventing seawater infiltration in subsea tunnel engineering. However, grouting composites are continuously subjected to harsh marine ...Grouting represents a reliable method for strengthening fractured rock masses and preventing seawater infiltration in subsea tunnel engineering. However, grouting composites are continuously subjected to harsh marine environments,experiencing both chemical and physical effects from high-concentration erosive seawater ions, elevated water pressure, and complex flow fields. This multi-factor erosion deterioration diminishes the waterproofing capabilities of grouting composites and threatens the service life of subsea tunnel linings. To investigate the erosion deteriortion mechanism induced by sulfate, erosion weakening experiments were conducted using a seawater flow simulation device. The research examined the compressive strength and permeability coefficient of grouting composites under different erosion durations, water-cement ratios, and grouting pressures. In the later stages of the experiment, the strength of grouting composites in the static water erosion control group(SEG) and dynamic water erosion group(DEG) decreased by 31.2% and 18.8%, respectively, compared to the freshwater control group(FG). Futhermore, the permeability coefficient exhibited significant increases. Subsequent microscopic analyses of the eroded grouting composites were performed. This research elucidated the erosion-weakening mechanism of grouting composites subjected to sulfate-induced degradation in complex marine environments. The study emphasizes the critical role of erosion resistance and durability in design and implementation. From practical perspective, this work establishes a foundation for developing enhanced strategies to improve the long-term performance and integrity of grouting composites in subsea tunnel applications.展开更多
The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous...The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous deep mining areas characterized by soft rock roadways,where it has demonstrated remarkable control results.This article systematically explores the evolution of grouted bolting,covering its theoretical foundations,design methods,materials,construction processes,monitoring measures,and methods for assessing its effectiveness.The overview encompassed several key elements,delving into anchoring theory and grouting reinforcement theory.The new principle of high pretensioned high-pressure splitting grouted bolting collaborative active control is introduced.A fresh method for dynamic information design is also highlighted.The discussion touches on both conventional grouting rock bolts and cable bolts,as well as innovative grouted rock bolts and cables characterized by their high pretension,strength,and sealing hole pressure.An examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic–organic composite materials,including their specific application conditions,was conducted.Additionally,the article presents various methods and instruments to assess the support effect of grouting rock bolts,cable bolts,and grouting reinforcement.Furthermore,it provides a foundation for understanding the factors influencing decisions on grouted bolting timing,the sequence of grouting,the pressure applied,the volume of grout used,and the strategic arrangement of grouted rock bolts and cable bolts.The application of the high pretensioned high-pressure splitting grouted bolting collaborative control technology in a typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kouzidong coal mine,Huainan coal mining area,was introduced.Finally,the existing problems in grouted bolting control technology for deep soft rock roadways are analyzed,and the future development trend of grouted bolting control technology is anticipated.展开更多
Soil is an essential component of what surrounds us in nature, providing as the basis for our infrastructure and construction. However, soil is not always suitable for construction due to a variety of geotechnical iss...Soil is an essential component of what surrounds us in nature, providing as the basis for our infrastructure and construction. However, soil is not always suitable for construction due to a variety of geotechnical issues such as inadequate bearing capacity, excessive settlement, and liquefaction susceptibility. Through improving the engineering qualities of soil, such as strength, permeability, and stability, ground grouting is a specific geotechnical method used. Using a fluid grout mixture injected into the subsurface, holes are filled and weak or loose strata are solidified as the material seeps into the soil matrix. The approach’s adaptability in addressing soil-related issues has made it more well-known in the fields of civil engineering and construction. In the end, this has improved groundwater management, foundation support, and overall geotechnical performance.展开更多
Grouting defects are an inherent challenge in construction practices,exerting a considerable impact on the operational structural integrity of connections.This investigation employed the impact-echo technique for the ...Grouting defects are an inherent challenge in construction practices,exerting a considerable impact on the operational structural integrity of connections.This investigation employed the impact-echo technique for the detection of grouting anomalies within connections,enhancing its precision through the integration of wavelet packet energy principles for damage identification purposes.A series of grouting completeness assessments were meticulously conducted,taking into account variables such as the divergent material properties of the sleeves and the configuration of adjacent reinforcement.The findings revealed that:(i)the energy distribution for the highstrength concrete cohort predominantly occupied the frequency bands 42,44,45,and 47,whereas for other groups,it was concentrated within the 37 to 40 frequency band;(ii)the delineation of empty sleeves was effectively discernible by examining the wavelet packet energy ratios across the spectrum of frequencies,albeit distinguishing between sleeves with 50%and full grouting density proved challenging;and(iii)the wavelet packet energy analysis yielded variable detection outcomes contingent on the material attributes of the sleeves,demonstrating heightened sensitivity when applied to ultrahigh-performance concrete matrices and GFRP-reinforced steel bars.展开更多
Bedding slope is a typical heterogeneous slope consisting of different soil/rock layers and is likely to slide along the weakest interface.Conventional slope protection methods for bedding slopes,such as retaining wal...Bedding slope is a typical heterogeneous slope consisting of different soil/rock layers and is likely to slide along the weakest interface.Conventional slope protection methods for bedding slopes,such as retaining walls,stabilizing piles,and anchors,are time-consuming and labor-and energy-intensive.This study proposes an innovative polymer grout method to improve the bearing capacity and reduce the displacement of bedding slopes.A series of large-scale model tests were carried out to verify the effectiveness of polymer grout in protecting bedding slopes.Specifically,load-displacement relationships and failure patterns were analyzed for different testing slopes with various dosages of polymer.Results show the great potential of polymer grout in improving bearing capacity,reducing settlement,and protecting slopes from being crushed under shearing.The polymer-treated slopes remained structurally intact,while the untreated slope exhibited considerable damage when subjected to loads surpassing the bearing capacity.It is also found that polymer-cemented soils concentrate around the injection pipe,forming a fan-shaped sheet-like structure.This study proves the improvement of polymer grouting for bedding slope treatment and will contribute to the development of a fast method to protect bedding slopes from landslides.展开更多
基金Funded by the National Natural Science Foundation of China(No.51979153)the Yunnan Key Research and Development Program(No.202103AA080016)。
文摘The cement-fly ash composite expansive stable grout was prepared to deal with the problems of poor stability and volume shrinkage of ordinary cement grout,and the effects of fly ash ratio and water-binder ratio on the properties of the grout and its consolidation were analyzed.In addition,the mineral composition and microstructural characteristics of grout consolidation with different mixing ratios were investigated.The experimental results indicate that fly ash and the increase of water-binder ratio reduce the strength of the grout consolidation,and increase the fluidity,bleeding rate,and setting time of the composite grout.However,the magnitude of the fly ash-induced strength reduction decreases with time.And the effect of fly ash on the setting time and compressive strength becomes more significant with the water-binder ratio.The later expansion performance of grout consolidation(after 7-42 d)is improved by fly ash.But the expansibility of consolidation with fly ash decreases at the early curing stage,and the reduction amplitude of expansion rate is smaller and the reduction age is shorter with the water-binder ratio increase.Fly ash improves the corrosion resistance performance of grout consolidation,and the corrosion resistance coefficient rises first and then falls with the fly ash ratio.And for 0.6:1 water-binder ratio,the corrosion resistance coefficient of the samples mixed with fly ash are greater than 100%.XRD and SEM show that fly ash inhibited the formation of ettringite in the early stage,which is unfavorable to the expansion of the slurry,and with the increase of age,this effect gradually weakened.
基金supported by the National Natural Science Foundation of China(NSFC)(grant No.52074169,No.51704280)the China Postdoctoral Science Foundation(No.2023M732109)the Opening Foundation of Shandong Key Laboratory of Civil Engineering Disaster Prevention and Mitigation(No.CDPM2021FK02).
文摘The fractured surrounding rocks of roadways pose major challenges to safe mining.Grouting has often been used to reinforce the surrounding rocks to mitigate the safety risks associated with fractured rocks.The aim of this study is to develop highly efficient composite ultrafine cement(CUC)grouts to reinforce the roadway in fractured surrounding rocks.The materials used are ultrafine cement(UC),ultrafine fly ash(UF),ultrafine slag(US),and additives(superplasticizer[SUP],aluminate ultrafine expansion agent[AUA],gypsum,and retarder).The fluidity,bleeding,shrinkage,setting time,chemical composition,microstructure,degree of hydration,and mechanical property of grouting materials were evaluated in this study.Also,a suitable and effective CUC grout mixture was used to reinforce the roadway in the fractured surrounding rock.The results have shown that the addition of UF and US reduces the plastic viscosity of CUC,and the best fluidity can be obtained by adding 40%UF and 10%US.Since UC and UF particles are small,the pozzolanic effect of UF promotes the hydration reaction,which is conductive to the stability of CUC grouts.In addition,fine particles of UC,UF,and US can effectively fill the pores,while the volumetric expansion of AUA and gypsum decreases the pores and thus affects the microstructure of the solidified grout.The compressive test results have shown that the addition of specific amounts of UF and US can ameliorate the mechanical properties of CUC grouts.Finally,the CUC22‐8 grout was used to reinforce the No.20322 belt roadway.The results of numerical simulation and field monitoring have indicated that grouting can efficaciously reinforce the surrounding rock of the roadway.In this research,high‐performance CUC grouts were developed for surrounding rock reinforcement of underground engineering by utilizing UC and some additives.
基金supported by the China Scholarship Council(CSC,Grant No.202108050072)JSPS KAKENHI(Grant No.JP19KK0121)。
文摘Grouting has been the most effective approach to mitigate water inrush disasters in underground engineering due to its ability to plug groundwater and enhance rock strength.Nevertheless,there is a lack of potent numerical tools for assessing the grouting effectiveness in water-rich fractured strata.In this study,the hydro-mechanical coupled discontinuous deformation analysis(HM-DDA)is inaugurally extended to simulate the grouting process in a water-rich discrete fracture network(DFN),including the slurry migration,fracture dilation,water plugging in a seepage field,and joint reinforcement after coagulation.To validate the capabilities of the developed method,several numerical examples are conducted incorporating the Newtonian fluid and Bingham slurry.The simulation results closely align with the analytical solutions.Additionally,a set of compression tests is conducted on the fresh and grouted rock specimens to verify the reinforcement method and calibrate the rational properties of reinforced joints.An engineering-scale model based on a real water inrush case of the Yonglian tunnel in a water-rich fractured zone has been established.The model demonstrates the effectiveness of grouting reinforcement in mitigating water inrush disaster.The results indicate that increased grouting pressure greatly affects the regulation of water outflow from the tunnel face and the prevention of rock detachment face after excavation.
基金Funded by a Science and Technology Project from the Ministry of Housing and Urban-Rural Development of the People’s Republic of China(No.2019-K-047)Yangzhou Government-Yangzhou University Cooperative Platform Project for Science and Technology Innovation(No.YZ2020262)。
文摘The chloride penetration resistance of cement-based grout materials was improved by nano-silica emulsion.Specimens of mixtures containing different nano-silica particles or emulsions were exposed in sodium chloride solutions of specific concentrations with different test ages.Hardened properties of the mixes were assessed in terms of weight loss and compressive strength.X-ray diffraction(XRD)and scanning electron microscopy(SEM)of mixes were performed to analysis the phase evolution and microstructure.The results demonstrated that the introduction of nano-SiO_(2) emulsion significantly decreased the compressive strength loss and calcium hydroxide(CH)crystal content of hydration production,and then enhanced the resistance of cement-based grouting materials to chloride ion penetration.This improvement derives from the filling and pozzolanic effects of nano-SiO_(2) particles,which were incorporated via an emulsion and attributed to a well dispersion in grouting matrix.
基金supported by the National Natural Science Foundation of China,Grant Nos.42477185,41602308the Zhejiang Provincial Natural Science Foundation of China,Grant No.LY20E080005+2 种基金the Zhejiang Province University Students Science and Technology Innovation Program,Grant No.0201310P28the PostGraduate Course Construction Project of Zhejiang University of Science and Technology,Grant No.2021yjskj05the Zhejiang University of Science and Technology Graduate Research and Innovation Fund,Grant No.2023yjskc10.
文摘The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.
基金supported by the National Natural Science Foundation of China(Grant No.U23A6018)Science and Technology Program of Hebei(Grant No.E2022202041,2022HBQZYCXY004,242Q9920Z)the project of“Key technologies of seepage control system for large-scale hydraulic projects”was also gratefully appreciated.
文摘Curtain grouting projects are characterized by their large scale and complexity,presenting significant challenges for real-time prediction of grout penetration using traditional methods.This study introduces an intelligent prediction method for grouting in fractured rock masses based on three core principles:integration of multi-source input features,fracture voxel modeling,and shortest path in sequential grouting.Three categories of data(geological structure data,grouting environmental data,and grouting operation data in the concept of a grouting geological model)are integrated and served as multi-source structured data in the intelligent prediction of grouting.A voxelization model quantifies the spatial characteristics of fractures,with voxel size optimized for capturing grouting paths.A shortest path algorithm based on a hierarchical solution is then developed to calculate grout penetration distances in the process of sequential grouting.A complete analysis framework is established,from the voxelization of the fracture network model to precise voxel classification,ultimately achieving an accurate prediction of grout penetration.The method demonstrates excellent performance on the test set,with validation against numerical methods in single-fracture and sequential grouting scenarios confirming its accuracy and prediction efficiency as hundreds of times faster than numerical methods.Application to the Dongzhuang hydraulic project’s grouting test area further validates its effectiveness in multi-hole grouting scenarios.
基金The National Natural Science Foundation of China,Grant/Award Number:42130706。
文摘Due to the invisibility and complexity of the underground spaces,monitoring the propagation and filling characteristics of the grouting slurry post the water–sand mixture inrush in metal mines is challenging,which complicates engineering treatment.This research investigated the propagation law of cement-sodium silicate slurry under flowing water conditions within the caving mass of a metal mine.First,based on borehole packer test results and borehole TV images,the fractured strata before grouting were classified into four types:cavity,hidden,fissure,and complete.Second,an orthogonal experimental design was employed to evaluate the impact of four key factors—stratigraphic fragmentation,water flow rate,grouting flow rate,and water-cement ratio—on the efficacy of grouting within a caving mass at the site.The results indicate that the factors influencing grouting efficacy are ranked in the following order of importance:stratigraphic fragmentation>water flow rate>water–cement ratio>grouting flow rate.Ultimately,five propagation filling modes—pure slurry,big crack,small crack,small karst pore,and pore penetration—were identified by examining the propagation filling characteristics of slurry in rock samples,incorporating microscopic material structure analysis through scanning electron microscopy and energy spectrum analysis.The findings of this study provide valuable insights into selecting engineering treatment parameters and methodologies,serving as a reference for preventing and controlling water–sand mixture inrush in metal mines,thereby enhancing treatment efficacy and ensuring grouting success.
基金supported by the Ministry of Education,Culture,Research,and Technology(Indonesia),Grant number 107/E5/PG.02.00.PL/2024,AZ.
文摘Concrete is one of the most important elements in building construction.However,concrete used in construction is susceptible to damage due to corrosion.The influence of corrosive substances causes changes in the reinforcing steel and affects the strength of the structure.The repair method is one approach to overcome this problem.This research aims to determine the effect of grouting and jacketing repairs on corroded concrete.The concrete used has dimensions of 15 cm×15 cm×60 cm with planned corrosion variations of 50%,60%,and 70%.The test objects were tested using the Non-Destructive Testing(NDT)method using Ultrasonic Pulse Velocity(UPV).The test results show that the average speed of normal concrete is 5070 m/s,while the lowest average speed is 3070 m/s on the 70%planned corrosion test object.The test object was then given a load of 1600 kgf.At this stage,there is a decrease in speed and wave shape with the lowest average speed obtained at 2753 m/s.The repair method is an effort to restore concrete performance by using grouting and jacketing.Grouting is done by injecting mortar material into it.Jacketing involves adding thickness to the existing concrete layer with additional layers of concrete.After improvements were made,there was an improvement in the UPV test,with a peak speed value of 4910 m/s.Repairing concrete by filling cracks can improve concrete continuity and reduce waveform distortion,thereby increasing wave propagation speed.
基金funded by the National Natural Science Foundation of China[U22A20234]Hubei Province key research and development project[2023BCB121]Wuhan innovation supporting projects[2023020201010079].
文摘Grouting is a widely applied technique for reinforcing fractured zones in deep soft rock tunnels.By infiltrating rock fissures,slurry materials enhance structural integrity and improve the overall stability of the surrounding rock.The performance of grouting is primarily governed by the flow behavior and diffusion extent of the slurry.This review considers recent advances in the theory and methodology of slurry flow and diffusion in fractured rock.It examines commonly used grout materials,including cement-based,chemical,and composite formulations,each offering distinct advantages for specific geological conditions.Themechanisms of reinforcement vary significantly across materials,requiring tailored application strategies.The rheological properties of grouting slurries,particularly cement-based types,have been widely modeled using classical constitutive approaches.However,the influence of time-and space-dependent viscosity evolution on slurry behavior remains underexplored.Experimental studies have provided valuable insights into slurry diffusion,yet further research is needed to capture real-time behavior under multi-scale and multi-physics coupling conditions.Similarly,current numerical simulations are largely limited to twoand three-dimensional models of single-fracture flow.These models often neglect the complexity of fracture networks and geological heterogeneity,highlighting a need for more realistic and integrated simulation frameworks.Future research should focus on:(1)fine-scale modeling of slurry hydration and mechanical reinforcement processes;(2)cross-scale analysis of slurry flow under coupled thermal,hydraulic,andmechanical fields;and(3)development of realtime,three-dimensional dynamic simulation tools to capture the full grouting process.These efforts will strengthen the theoretical foundation and practical effectiveness of grouting in complex underground environments.
基金funded by the National Natural Science Foundation of China(No.51974206)the Hubei Province Safety Production Special Fund Science and Technology Project(No.KJZX202007007).
文摘In the civil and mining industries,bolts are critical components of support systems,playing a vital role in ensuring their stability.Glass fibre reinforced polymer(GFRP)bolts are widely used because they are corrosion-resistant and cost-effective.However,the damage mechanisms of GFRP bolts under blasting dynamic loads are still unclear,especially compared to metal bolts.This study investigates the cumulative damage of fully grouted GFRP bolts under blasting dynamic loads.The maximum axial stress at the tails of the bolts is defined as the damage variable,based on the failure characteristics of GFRP bolts.By combining this with Miner's cumulative damage theory,a comprehensive theoretical and numerical model is established to calculate cumulative damage.Field data collected from the Jinchuan No.3 Mining Area,including GFRP bolts parameters and blasting vibration data are used for further analysis of cumulative damage in fully grouted GFRP bolts.Results indicate that with an increasing number of blasts,axial stress increases in all parts of GFRP bolts.The tail exhibits the most significant rise,with stress extending deeper into the anchorage zone.Cumulative damage follows an exponential trend with the number of blasts,although the incremental damage per blast decelerates over time.Higher dynamic load intensities accelerate damage accumulation,leading to an exponential decline in the maximum loading cycles before failure.Additionally,stronger surrounding rock and grout mitigate damage accumulation,with the effect of surrounding rock strength being more pronounced than that of grout.In contrast,the maximum axial stress of metal bolts increases quickly to a certain point and then stabilizes.This shows a clear difference between GFRP and metal bolts.This study presents a new cumulative damage theory that underpins the design of GFRP bolt support systems under blasting conditions,identifies key damage factors,and suggests mitigation measures to enhance system stability.
基金the National Natural Science Foundation of China(Grant Nos.42172298,42002289)the Shanghai Geological Star Program for their financial support.
文摘Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were conducted,with varying pressures from 400 kPa to 800 kPa,to quantitatively evaluate the densification effect in unsaturated soils.The response of surrounding soil during compaction grouting was monitored.The changes in dry density and void ratio induced by compaction grouting were obtained by monitoring volumetric water content to determine compaction efficiency.In addition,a model was developed and validated to predict the effective compaction range.The results show that soil dry density increased rapidly during compaction grouting before being stabilized at a consistent level.As expected,it is positively correlated with grouting pressures(GPs)and negatively correlated with the distance from the injection point.At higher GPs,the difference in densification effect around the injection point after compaction grouting was significant.Interestingly,variations in ultimate dry density and peak earth pressures perpendicular to the injection direction exhibited axisymmetric behavior around the injection point when comparing the dry density and earth pressure results.Furthermore,soil densification resulted in a decrease in suction.However,no significant effect of GP on suction at different soil positions was observed.Moreover,compaction efficiency decreased with increasing distance from the injection point,showing a strong linear relationship.In addition,the model results for the effective compaction range were basically consistent with the extrapolated values from the experimental results.
基金supported by the National Natural Science Foundation of China(No.42477185)Natural Science Foundation of Zhejiang Province(LQ24A020015)+1 种基金Research Achievement Award Cultivation Project of Zhejiang University of Science and Technology(2023JLYB001)the Postgraduate Course Construction Project of Zhejiang University of Science and Technology(2024yjskj05).
文摘The rapid development of urban rail transit has posed increasing construction and operational challenges for metro tunnels,often leading to structural damage.Grouting technology using cement-based materials is widely applied to address issues such as seepage,leakage,and alignment correction in shield tunnels.This study investigates the additional stress induced by grouting in silty soil layers,using cement-based grouts with different water-to-cement ratios and polyurethane-modified cement-based materials.Results show that additional stress decreases with depth and is more influenced by horizontal distance from the grouting point.In staged grouting,the first injection phase contributes about 50%of the peak additional stress.A lower water-to-cement ratio(e.g.,0.6)increases additional stress but reduces grout flowability,while a higher ratio improves diffusion but increases the risk of grout loss.(≥1.0)The polyurethane-modified cement-based material enhances stress transfer performance,increasing peak additional stress by approximately 10%.These findings provide theoretical guidance for optimizing material selection and grouting design in metro tunnel repair within silty soil layers.
基金National Natural Science Foundation of China,Grant/Award Number:41902292。
文摘Groundwater inrush is a hazard that always occurs during underground mining.Grouting is one of the most effective processes to seal underground water inflow for hazard prevention.In this study,grouting experiments are conducted by using a visualized transparent single-fracture replica with plane roughness.Image processing and analysis are performed to investigate the thermo–hydro–mechanical coupling effect on the grouting diffusion under coal mine flowing water conditions.The results show that higher ambient temperature leads to shorter initial gel time of chemical grout and leads to a better relative sealing efficiency in the case of a lower flow rate.However,with a higher water flow rate,the relative sealing efficiency is gradually reduced under higher temperature conditions.The grouting pressure,the seepage pressure,and the temperature are measured.The results reveal that the seepage pressure shows a positive correlation with the grouting pressure,while the temperature change shows a negative correlation with the seepage pressure and the grouting pressure.The“equivalent grouting point offset”effect of grouting shows an eccentric elliptical diffusion with larger grouting distance and width under lower temperature conditions.
文摘As the cost of grouting treatment for water control in coal roofs during underground coal mining continues to rise,coupled with the accumulation of industrial solid waste resulting from rapid economic development in China,the ecological environment is facing severe challenges.To address these issues,this study,based on a high water-to-cement ratio,uses mine overburden(OB)and furnace bottom ash(FBA)as the primary raw materials,with sodium silicate as the modifier,to develop a new type of geopolymer grouting material with high stability and compressive strength for coal roof water control.Additionally,COMSOL software was used to numerically simulate the diffusion process of the grout slurry in fractures under dynamic water flow.The results indicate that,with a sodium silicate modulus of 1.5 and a dosage of 4%,the stability of the slurry increased by 26.2%,and the 28-day compressive strength improved by 130.98%.Numerical simulations further show that the diffusion process of the slurry is closely related to slurry viscosity,grouting pressure,and grouting time and that the diffusion pattern in the fractures is similar to that of ultra-fine cement slurry.This study provides a theoretical basis for coal mine roof grouting water control projects.
基金the funding support from the Natural Science Foundation of China(Grant No.52130402)the Anhui Province Graduate Education Quality Engineering Project(Grant No.2023cxcysj088)the China Scholarship Council Grants Program(Grant No.202308340082).
文摘Grouting injection is a vital technique for addressing the challenges of high stress and significant deformation in the surrounding rock during deep mining operations,playing a crucial role in promoting green and low-carbon extraction methodologies.In this study,grouting reinforcement processes were examined by conducting grouting experiments on a fractured rock with varying negative pressures(0-100 kPa),followed by uniaxial compression testing of the grout-reinforced bodies.This investigation explored the diffusion patterns of grout under negative pressure and established a constitutive model of damage-bearing capacity for bodies reinforced by negative pressure grouting.It further studied the enhancement effect of negative pressure on the load-bearing capacity of the reinforced bodies and analyzed the instability mechanism of damage and failure in these bodies.The results indicated that the diffusion of grout under negative pressure is influenced by four types of forces,which alter the extent of grout diffusion within the fractured rock mass.Introducing a damage constitutive model that serially connects pore and framework elements characterizes the damage and failure behavior of groutreinforced bodies under different negative pressures.As the negative pressure increases,changes in porosity,water-to-cement ratio,and admixture quantity occur in the grout-reinforced specimens,with the strength mean curve showing a trend of first increasing and then decreasing,reaching a threshold at a negative pressure of 60 kPa.With increasing negative pressure,the negative pressure damage variable decreases and then increases,and the stronger the interfacial microelement connections caused by the negative pressure,the greater the bearing capacity,ultimately manifesting in different failure modes.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 42477194 and 52279115)Fundamental Research Funds for the Central Universities (Grant No. 202441008)。
文摘Grouting represents a reliable method for strengthening fractured rock masses and preventing seawater infiltration in subsea tunnel engineering. However, grouting composites are continuously subjected to harsh marine environments,experiencing both chemical and physical effects from high-concentration erosive seawater ions, elevated water pressure, and complex flow fields. This multi-factor erosion deterioration diminishes the waterproofing capabilities of grouting composites and threatens the service life of subsea tunnel linings. To investigate the erosion deteriortion mechanism induced by sulfate, erosion weakening experiments were conducted using a seawater flow simulation device. The research examined the compressive strength and permeability coefficient of grouting composites under different erosion durations, water-cement ratios, and grouting pressures. In the later stages of the experiment, the strength of grouting composites in the static water erosion control group(SEG) and dynamic water erosion group(DEG) decreased by 31.2% and 18.8%, respectively, compared to the freshwater control group(FG). Futhermore, the permeability coefficient exhibited significant increases. Subsequent microscopic analyses of the eroded grouting composites were performed. This research elucidated the erosion-weakening mechanism of grouting composites subjected to sulfate-induced degradation in complex marine environments. The study emphasizes the critical role of erosion resistance and durability in design and implementation. From practical perspective, this work establishes a foundation for developing enhanced strategies to improve the long-term performance and integrity of grouting composites in subsea tunnel applications.
基金the National Natural Science Foundation of China(Nos.52304141 and 52074154)。
文摘The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous deep mining areas characterized by soft rock roadways,where it has demonstrated remarkable control results.This article systematically explores the evolution of grouted bolting,covering its theoretical foundations,design methods,materials,construction processes,monitoring measures,and methods for assessing its effectiveness.The overview encompassed several key elements,delving into anchoring theory and grouting reinforcement theory.The new principle of high pretensioned high-pressure splitting grouted bolting collaborative active control is introduced.A fresh method for dynamic information design is also highlighted.The discussion touches on both conventional grouting rock bolts and cable bolts,as well as innovative grouted rock bolts and cables characterized by their high pretension,strength,and sealing hole pressure.An examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic–organic composite materials,including their specific application conditions,was conducted.Additionally,the article presents various methods and instruments to assess the support effect of grouting rock bolts,cable bolts,and grouting reinforcement.Furthermore,it provides a foundation for understanding the factors influencing decisions on grouted bolting timing,the sequence of grouting,the pressure applied,the volume of grout used,and the strategic arrangement of grouted rock bolts and cable bolts.The application of the high pretensioned high-pressure splitting grouted bolting collaborative control technology in a typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kouzidong coal mine,Huainan coal mining area,was introduced.Finally,the existing problems in grouted bolting control technology for deep soft rock roadways are analyzed,and the future development trend of grouted bolting control technology is anticipated.
文摘Soil is an essential component of what surrounds us in nature, providing as the basis for our infrastructure and construction. However, soil is not always suitable for construction due to a variety of geotechnical issues such as inadequate bearing capacity, excessive settlement, and liquefaction susceptibility. Through improving the engineering qualities of soil, such as strength, permeability, and stability, ground grouting is a specific geotechnical method used. Using a fluid grout mixture injected into the subsurface, holes are filled and weak or loose strata are solidified as the material seeps into the soil matrix. The approach’s adaptability in addressing soil-related issues has made it more well-known in the fields of civil engineering and construction. In the end, this has improved groundwater management, foundation support, and overall geotechnical performance.
基金supported by financial support from the National Natural Science Foundation of China(U1904177)the Excellent Youth Natural Science Foundation of Henan Province of China(212300410079)+2 种基金the Subproject of the Key Project of the National Development and Reform Commission of China(202203001)the Project of Young Key Teachers in Henan Province of China(2019GGJS01)Horizontal Research Projects(20230352A).
文摘Grouting defects are an inherent challenge in construction practices,exerting a considerable impact on the operational structural integrity of connections.This investigation employed the impact-echo technique for the detection of grouting anomalies within connections,enhancing its precision through the integration of wavelet packet energy principles for damage identification purposes.A series of grouting completeness assessments were meticulously conducted,taking into account variables such as the divergent material properties of the sleeves and the configuration of adjacent reinforcement.The findings revealed that:(i)the energy distribution for the highstrength concrete cohort predominantly occupied the frequency bands 42,44,45,and 47,whereas for other groups,it was concentrated within the 37 to 40 frequency band;(ii)the delineation of empty sleeves was effectively discernible by examining the wavelet packet energy ratios across the spectrum of frequencies,albeit distinguishing between sleeves with 50%and full grouting density proved challenging;and(iii)the wavelet packet energy analysis yielded variable detection outcomes contingent on the material attributes of the sleeves,demonstrating heightened sensitivity when applied to ultrahigh-performance concrete matrices and GFRP-reinforced steel bars.
基金supported by the Fujian Science Foundation for Outstanding Youth(Grant No.2023J06039)the National Natural Science Foundation of China(Grant No.41977259 and No.U2005205)Fujian Province natural resources science and technology innovation project(Grant No.KY-090000-04-2022-019)。
文摘Bedding slope is a typical heterogeneous slope consisting of different soil/rock layers and is likely to slide along the weakest interface.Conventional slope protection methods for bedding slopes,such as retaining walls,stabilizing piles,and anchors,are time-consuming and labor-and energy-intensive.This study proposes an innovative polymer grout method to improve the bearing capacity and reduce the displacement of bedding slopes.A series of large-scale model tests were carried out to verify the effectiveness of polymer grout in protecting bedding slopes.Specifically,load-displacement relationships and failure patterns were analyzed for different testing slopes with various dosages of polymer.Results show the great potential of polymer grout in improving bearing capacity,reducing settlement,and protecting slopes from being crushed under shearing.The polymer-treated slopes remained structurally intact,while the untreated slope exhibited considerable damage when subjected to loads surpassing the bearing capacity.It is also found that polymer-cemented soils concentrate around the injection pipe,forming a fan-shaped sheet-like structure.This study proves the improvement of polymer grouting for bedding slope treatment and will contribute to the development of a fast method to protect bedding slopes from landslides.
