Cyclic triaxial tests and numerical analyses were undertaken, in order to evaluate the wave-induced pore water pressure in seabed sediments in the Hangzhou Bay. The cyclic triaxial tests indicate that the rate of pore...Cyclic triaxial tests and numerical analyses were undertaken, in order to evaluate the wave-induced pore water pressure in seabed sediments in the Hangzhou Bay. The cyclic triaxial tests indicate that the rate of pore water pressure generation in cohesive soils decreases with time, and the development of the pore water pressure can be represented by a hyperbolic curve. Numerical analyses, taking into account the generation and dissipation of pore water pressure simultaneously, suggest that the pore water pressure buildup in cohesive soils may increase with time continuously until the pore water pressure ratio approaches to 1, or it may decrease after a certain time, which is controlled by drain conditions. These phenomena are different from those in sands. For waves with a retum period of 100 a in the Hangzhou Bay, if the wave duration is more than 60 h, then the pore water pressure ratio will be close to 1 and soil fabric failure will take place.展开更多
The complex geometry and topology of soil is widely recognised as the key driver in many ecological processes. X-ray computed tomography (CT) provides insight into the internal structure of soil pores automatically an...The complex geometry and topology of soil is widely recognised as the key driver in many ecological processes. X-ray computed tomography (CT) provides insight into the internal structure of soil pores automatically and accurately. Until recently, there have not been methods to identify soil pore structures. This has restricted the development of soil science, particularly regarding pore geometry and spatial distribution. Through the adoption of the fuzzy clustering theory and the establishment of pore identification rules, a novel pore identification method is described to extract pore structures from CT soil images. The robustness of the adaptive fuzzy C-means method (AFCM), the adaptive threshold method, and Image-Pro Plus tools were compared on soil specimens under different conditions, such as frozen, saturated, and dry situations. The results demonstrate that the AFCM method is suitable for identifying pore clusters, especially tiny pores, under various soil conditions. The method would provide an optional technique for the study of soil micromorphology.展开更多
This paper describes a systematic study on the fundamental features of seismic soil pressure on underground tunnels, in terms of its magnitude and distribution, and further identifi es the dominant factors that signif...This paper describes a systematic study on the fundamental features of seismic soil pressure on underground tunnels, in terms of its magnitude and distribution, and further identifi es the dominant factors that signifi cantly infl uence the seismic soil pressure. A tunnel embedded in water-saturated poroelastic half-space is considered, with a large variety of model and excitation parameters. The primary features of both the total soil pressure and the pore pressure are investigated. Taking a circular tunnel as an example, the results are presented using a fi nite element-indirect boundary element(FE-IBE) method, which can account for dynamic soil-tunnel interaction and solid frame-pore water coupling. The effects of tunnel stiffness, tunnel buried depth and input motions on the seismic soil pressure and pore pressure are also examined. It is shown that the most crucial factors that dominate the magnitude and distribution of the soil pressure are the tunnel stiffness and dynamic soil-tunnel interaction. Moreover, the solid frame-pore water coupling has a prominent infl uence on the magnitude of the pore pressure. The fi ndings are benefi cial to obtain insight into the seismic soil pressure on underground tunnels, thus facilitating more accurate estimation of the seismic soil pressure.展开更多
Inundation of the Three Gorges Reservoir has created a 30-m water-level fluctuation zone with seasonal hydrological alternations of submergence and exposure, which may greatly affect soil properties and bank stability...Inundation of the Three Gorges Reservoir has created a 30-m water-level fluctuation zone with seasonal hydrological alternations of submergence and exposure, which may greatly affect soil properties and bank stability. The aim of this study was to investigate the response of soil pore structure to seasonal water-level fluctuation in the reservoir, and particularly, the hydrological change of wetting and drying cycles. Soil pore structure was visualized with industrial X-ray computed tomography and digital image analysis techniques. The results showed that soil total porosity(? 100 ?m), total pore number, total throat number, and mean throat surface area increased significantly under wetting and drying cycles. Soil porosity, pore number and throat numberwithin each size class increased in the course of wetting and drying cycles. The coordination number, degree of anisotropy and fractal dimension were indicating an increase. In contrast, the mean shape factor, pore-throat ratio, and Euler-Poincaré number decreased due to wetting and drying cycles. These illustrated that the wetting and drying cycles made soil pore structure become more porous, continuous, heterogeneous and complex. It can thus be deduced that the water-level fluctuation would modify soil porosity, pore size distribution, and pore morphology in the Three Gorges Reservoir, which may have profound implications for soil processes, soil functions, and bank stability.展开更多
Due to seasonal climate alterations,the microstructure and permeability of granite residual soil are easily affected by multiple dry-wet cycles.The X-ray micro computed tomography(micro-CT)acted as a nondestructive to...Due to seasonal climate alterations,the microstructure and permeability of granite residual soil are easily affected by multiple dry-wet cycles.The X-ray micro computed tomography(micro-CT)acted as a nondestructive tool for characterizing the microstructure of soil samples exposed to a range of damage levels induced by dry-wet cycles.Subsequently,the variations of pore distribution and permeability due to drywet cycling effects were revealed based on three-dimensional(3D)pore distribution analysis and seepage simulations.According to the results,granite residual soils could be separated into four different components,namely,pores,clay,quartz,and hematite,from micro-CT images.The reconstructed 3D pore models dynamically demonstrated the expanding and connecting patterns of pore structures during drywet cycles.The values of porosity and connectivity are positively correlated with the number of dry-wet cycles,which were expressed by exponential and linear functions,respectively.The pore volume probability distribution curves of granite residual soil coincide with the χ^(2)distribution curve,which verifies the effectiveness of the assumption of χ^(2)distribution probability.The pore volume distribution curves suggest that the pores in soils were divided into four types based on their volumes,i.e.micropores,mesopores,macropores,and cracks.From a quantitative and visual perspective,considerable small pores are gradually transformed into cracks with a large volume and a high connectivity.Under the action of dry-wet cycles,the number of seepage flow streamlines which contribute to water permeation in seepage simulation increases distinctly,as well as the permeability and hydraulic conductivity.The calculated hydraulic conductivity is comparable with measured ones with an acceptable error margin in general,verifying the accuracy of seepage simulations based on micro-CT results.展开更多
The geometric and spatial characteristics of pore structures determine the permeability and water retention of soils, which have important effects on soil functional diversity and ecological restoration. Until recentl...The geometric and spatial characteristics of pore structures determine the permeability and water retention of soils, which have important effects on soil functional diversity and ecological restoration. Until recently, there have not been tools and methods to visually and quantitatively describe the characteristics of soil pores. To solve this problem, this research reconstructs the geometry and spatial distribution of soil pores by the marching cubes method, texture mapping method and the ray casting method widely used in literature. The objectives were to explore an optimal method for three-dimensional visualization of soil pore structure by comparing the robustness of the three methods on soil CT images with single pore structure and porosity ranging from low (2–5%) to high (12–18%), and to evaluate the reconstruction performance of the three methods with different geometric features. The results demonstrate that there are aliases (jagged edges) and deficiency at the boundaries of the model reconstructed by the marching cubes method and pore volumes are smaller than the ground truth, whereas the results of the texture mapping method lack the details of pore structures. For all the soil images, the ray casting method is preferable since it better preserves the pore characteristics of the ground truth. Furthermore, the ray casting method produced the best soil pore model with higher rendering speed and lower memory consumption. Therefore, the ray casting method provides a more advanced method for visualization of pore structures and provides an optional technique for the study of the transport of moisture and the exchange of air in soil.展开更多
Variability in moisture content is a common condition in natural soils.It influences soil properties significantly.A comprehensive understanding of the evolution of soil microstructure in wetting/drying process is of ...Variability in moisture content is a common condition in natural soils.It influences soil properties significantly.A comprehensive understanding of the evolution of soil microstructure in wetting/drying process is of great significance for interpretation of soil macro hydro-mechanical behavior.In this review paper,methods that are commonly used to study soil microstructure are summarized.Among them are scanning electron microscope(SEM),environmental SEM(ESEM),mercury intrusion porosimetry(MIP)and computed tomography(CT)technology.Moreover,progress in research on the soil microstructure evolution during drying,wetting and wetting/drying cycles is summarized based on reviews of a large body of research papers published in the past several decades.Soils compacted on the wet side of op-timum water content generally have a matrix-type structure with a monomodal pore size distribution(PSD),whereas soils compacted on the dry side of optimum water content display an aggregate structure that exhibits bimodal PSD.During drying,decrease in soil volume is mainly caused by the shrinkage of inter-aggregate pores.During wetting,both the intra-and inter-aggregate pores increase gradually in number and sizes.Changes in the characteristics of the soil pore structure significantly depend on stress state as the soil is subjected to wetting.During wetting/drying cycles,soil structural change is not completely reversible,and the generated cumulative swelling/shrinkage deformation mainly derives from macro-pores.Furthermore,based on this analysis and identified research needs,some important areas of research focus are proposed for future work.These areas include innovative methods of sample preparation,new observation techniques,fast quantitative analysis of soil structure,integration of microstructural parameters into macro-mechanical models,and soil microstructure evolution charac-teristics under multi-field coupled conditions.展开更多
In this paper,mercury intrusion porosimetry(MIP)is used to test the pore structure of non-dispersible underwater concrete so as to study the influence of pouring and curing environment,age and slag powder on the pore ...In this paper,mercury intrusion porosimetry(MIP)is used to test the pore structure of non-dispersible underwater concrete so as to study the influence of pouring and curing environment,age and slag powder on the pore characteristics of concrete,analyze the pore characteristics,porosity and pore distribution of concrete in different hydration stages,and reveal the relationship between pore structure and permeability of concrete.The results show that the pore-size distribution of concrete in fresh water condition is better than that in sulfate environment and mixed salt environment,and therefore,sulfate as well as mixed salt are not conducive to the development of pore structure of non-dispersible underwater concrete;chlorine salt has little effect on the pore structure of nondispersible underwater concrete;under the three conditions of sulfate,chlorine and mixed salt,the porosity of concrete mixed with slag powder is lower than that of concrete without slag powder.The results indicate that the addition of slag powder can ameliorate the pore size distribution of non-dispersed underwater concrete,reduce the porosity,and make the concrete structure more compact,which is beneficial to improve the permeability resistance of concrete at the macro level.展开更多
The building of the infrastructure on the compressible and saturated soils presents sometimes major difficulties. The infrastructure undergoes strong settlement that can be due to several phenomena of consolidation of...The building of the infrastructure on the compressible and saturated soils presents sometimes major difficulties. The infrastructure undergoes strong settlement that can be due to several phenomena of consolidation of the soils. The latter results from the dissipation of the excess pore pressure and deformation of the solid skeleton. Terzaghi theory led to the equation modeling the dissipation of excess pore pressure. The objective of this study is to establish solutions, by analytical and numerical method, of the equation of the pore water pressure. We considered a compressible saturated soil layer, between two drainage areas and subjected to a uniform load. Separation of variables is used to obtain an analytical solution and the finite element method for the numerical solution. The results obtained by the finite element method have validated those of analytical resolution.展开更多
Pore water pressure has an important influence on mechanical properties of soil.The authors studied the characteristics of pore water pressure dissipating of mucky soil under consolidated-drained condition by using re...Pore water pressure has an important influence on mechanical properties of soil.The authors studied the characteristics of pore water pressure dissipating of mucky soil under consolidated-drained condition by using refitted triaxial instrument and analyzed the variation of pore pressure coefficient with consolidation pressure.The results show that the dissipating of pore water pressure behaves in different ways depends on different styles of loading.What is more,the pore water pressure coefficient of mucky soil is less than 1.As the compactness of soil increases and moisture content reduces,the value of B reduces.There is a staggered dissipating in the process of consolidation,in which it is a mutate point when U/P is 80%.It is helpful to establish the pore water pressure model and study the strength-deformation of soil in process of consolidation.展开更多
In seasonal frozen soil region,the engineering geological properties of loess-like soil will be deteriorated after freeze-thaw cycles.Through the freeze-thaw cycle experiment of remolded loess-like soil,under differen...In seasonal frozen soil region,the engineering geological properties of loess-like soil will be deteriorated after freeze-thaw cycles.Through the freeze-thaw cycle experiment of remolded loess-like soil,under different freezing temperatures,the authors carried out freeze-thaw cycle tests for 3 times and 20 times,respectively.With mercury intrusion porosimetry and granulometric analysis,from the micro-structure,the authors studied the law that freeze-thaw cycle times and frozen temperature effect on the variation of microscopic pore of loesslike soil.This result can provide theoretical basis for comprehensive treatment of problems in the construction of the project in seasonal frozen loess-like soil region.展开更多
Because of the cementation inherited from the parent rock,weathered granitic soil is usually susceptible to disturbance,which poses considerable challenges for laboratory characterization.The cone penetration test wit...Because of the cementation inherited from the parent rock,weathered granitic soil is usually susceptible to disturbance,which poses considerable challenges for laboratory characterization.The cone penetration test with pore pressure measurements has long been known for its reliability in site investigations and stratigraphic profiling.However,although extensive piezocone test results and experience are available for sedimentary soil,similar advances are yet to be made for weathered granitic soil.Moreover,the experience from sedimentary soil may not be directly applicable to weathered profiles because of the essentially different natures of the two types of geomaterials.This study performs seismic piezocone tests in a weathered granitic profile comprising residual granitic soil,completely weathered granite,and highly weathered granite.Pore pressure is measured at both the cone mid-face and the shoulder,and the effects of penetrometer size and penetration rate are considered.A series of updated soil behavior type charts is proposed to interpret the test results,thereby allowing the effect of weathering to be evaluated.This paper offers an important extension to the sparse data on the in situ responses of weathered materials.展开更多
基金This work was supported by the National Natural Science Foundation of China under the contract Nos 10372089 and 40476032.
文摘Cyclic triaxial tests and numerical analyses were undertaken, in order to evaluate the wave-induced pore water pressure in seabed sediments in the Hangzhou Bay. The cyclic triaxial tests indicate that the rate of pore water pressure generation in cohesive soils decreases with time, and the development of the pore water pressure can be represented by a hyperbolic curve. Numerical analyses, taking into account the generation and dissipation of pore water pressure simultaneously, suggest that the pore water pressure buildup in cohesive soils may increase with time continuously until the pore water pressure ratio approaches to 1, or it may decrease after a certain time, which is controlled by drain conditions. These phenomena are different from those in sands. For waves with a retum period of 100 a in the Hangzhou Bay, if the wave duration is more than 60 h, then the pore water pressure ratio will be close to 1 and soil fabric failure will take place.
基金supported by the National Natural Science Youth Foundation of China(No.41501283)the Fundamental Research Funds for the Central Universities(2015ZCQGX-04)
文摘The complex geometry and topology of soil is widely recognised as the key driver in many ecological processes. X-ray computed tomography (CT) provides insight into the internal structure of soil pores automatically and accurately. Until recently, there have not been methods to identify soil pore structures. This has restricted the development of soil science, particularly regarding pore geometry and spatial distribution. Through the adoption of the fuzzy clustering theory and the establishment of pore identification rules, a novel pore identification method is described to extract pore structures from CT soil images. The robustness of the adaptive fuzzy C-means method (AFCM), the adaptive threshold method, and Image-Pro Plus tools were compared on soil specimens under different conditions, such as frozen, saturated, and dry situations. The results demonstrate that the AFCM method is suitable for identifying pore clusters, especially tiny pores, under various soil conditions. The method would provide an optional technique for the study of soil micromorphology.
基金Supported by:National Natural Science Foundation of China under Grant No.51978462
文摘This paper describes a systematic study on the fundamental features of seismic soil pressure on underground tunnels, in terms of its magnitude and distribution, and further identifi es the dominant factors that signifi cantly infl uence the seismic soil pressure. A tunnel embedded in water-saturated poroelastic half-space is considered, with a large variety of model and excitation parameters. The primary features of both the total soil pressure and the pore pressure are investigated. Taking a circular tunnel as an example, the results are presented using a fi nite element-indirect boundary element(FE-IBE) method, which can account for dynamic soil-tunnel interaction and solid frame-pore water coupling. The effects of tunnel stiffness, tunnel buried depth and input motions on the seismic soil pressure and pore pressure are also examined. It is shown that the most crucial factors that dominate the magnitude and distribution of the soil pressure are the tunnel stiffness and dynamic soil-tunnel interaction. Moreover, the solid frame-pore water coupling has a prominent infl uence on the magnitude of the pore pressure. The fi ndings are benefi cial to obtain insight into the seismic soil pressure on underground tunnels, thus facilitating more accurate estimation of the seismic soil pressure.
基金funded by the National Natural Science Foundation of China(Grant No.41771321,41771320 and 41571278)Sichuan Science and Technology Program(Grant No.2018SZ0132)
文摘Inundation of the Three Gorges Reservoir has created a 30-m water-level fluctuation zone with seasonal hydrological alternations of submergence and exposure, which may greatly affect soil properties and bank stability. The aim of this study was to investigate the response of soil pore structure to seasonal water-level fluctuation in the reservoir, and particularly, the hydrological change of wetting and drying cycles. Soil pore structure was visualized with industrial X-ray computed tomography and digital image analysis techniques. The results showed that soil total porosity(? 100 ?m), total pore number, total throat number, and mean throat surface area increased significantly under wetting and drying cycles. Soil porosity, pore number and throat numberwithin each size class increased in the course of wetting and drying cycles. The coordination number, degree of anisotropy and fractal dimension were indicating an increase. In contrast, the mean shape factor, pore-throat ratio, and Euler-Poincaré number decreased due to wetting and drying cycles. These illustrated that the wetting and drying cycles made soil pore structure become more porous, continuous, heterogeneous and complex. It can thus be deduced that the water-level fluctuation would modify soil porosity, pore size distribution, and pore morphology in the Three Gorges Reservoir, which may have profound implications for soil processes, soil functions, and bank stability.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12102312 and 41372314)State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Open Foundation, Chengdu University of Technology, China (Grant No. SKLGP2021K011)
文摘Due to seasonal climate alterations,the microstructure and permeability of granite residual soil are easily affected by multiple dry-wet cycles.The X-ray micro computed tomography(micro-CT)acted as a nondestructive tool for characterizing the microstructure of soil samples exposed to a range of damage levels induced by dry-wet cycles.Subsequently,the variations of pore distribution and permeability due to drywet cycling effects were revealed based on three-dimensional(3D)pore distribution analysis and seepage simulations.According to the results,granite residual soils could be separated into four different components,namely,pores,clay,quartz,and hematite,from micro-CT images.The reconstructed 3D pore models dynamically demonstrated the expanding and connecting patterns of pore structures during drywet cycles.The values of porosity and connectivity are positively correlated with the number of dry-wet cycles,which were expressed by exponential and linear functions,respectively.The pore volume probability distribution curves of granite residual soil coincide with the χ^(2)distribution curve,which verifies the effectiveness of the assumption of χ^(2)distribution probability.The pore volume distribution curves suggest that the pores in soils were divided into four types based on their volumes,i.e.micropores,mesopores,macropores,and cracks.From a quantitative and visual perspective,considerable small pores are gradually transformed into cracks with a large volume and a high connectivity.Under the action of dry-wet cycles,the number of seepage flow streamlines which contribute to water permeation in seepage simulation increases distinctly,as well as the permeability and hydraulic conductivity.The calculated hydraulic conductivity is comparable with measured ones with an acceptable error margin in general,verifying the accuracy of seepage simulations based on micro-CT results.
基金supported by the National Natural Science Foundation Project(41501283)Beijing Science and Technology Plan Project(Z161100000916012)+2 种基金the National Key Research and Development Program(2017YFD0600901)Special Fund for Beijing Common Construction Projectthe Fundamental Research Funds for the Central Universities(2015ZCQ-GX-04)
文摘The geometric and spatial characteristics of pore structures determine the permeability and water retention of soils, which have important effects on soil functional diversity and ecological restoration. Until recently, there have not been tools and methods to visually and quantitatively describe the characteristics of soil pores. To solve this problem, this research reconstructs the geometry and spatial distribution of soil pores by the marching cubes method, texture mapping method and the ray casting method widely used in literature. The objectives were to explore an optimal method for three-dimensional visualization of soil pore structure by comparing the robustness of the three methods on soil CT images with single pore structure and porosity ranging from low (2–5%) to high (12–18%), and to evaluate the reconstruction performance of the three methods with different geometric features. The results demonstrate that there are aliases (jagged edges) and deficiency at the boundaries of the model reconstructed by the marching cubes method and pore volumes are smaller than the ground truth, whereas the results of the texture mapping method lack the details of pore structures. For all the soil images, the ray casting method is preferable since it better preserves the pore characteristics of the ground truth. Furthermore, the ray casting method produced the best soil pore model with higher rendering speed and lower memory consumption. Therefore, the ray casting method provides a more advanced method for visualization of pore structures and provides an optional technique for the study of the transport of moisture and the exchange of air in soil.
基金This work was supported by National Natural Science Founda-tion of China(Grant Nos.41925012 and 41902271)Natural Science Foundation of Jiangsu Province(Grant No.BK20211087).
文摘Variability in moisture content is a common condition in natural soils.It influences soil properties significantly.A comprehensive understanding of the evolution of soil microstructure in wetting/drying process is of great significance for interpretation of soil macro hydro-mechanical behavior.In this review paper,methods that are commonly used to study soil microstructure are summarized.Among them are scanning electron microscope(SEM),environmental SEM(ESEM),mercury intrusion porosimetry(MIP)and computed tomography(CT)technology.Moreover,progress in research on the soil microstructure evolution during drying,wetting and wetting/drying cycles is summarized based on reviews of a large body of research papers published in the past several decades.Soils compacted on the wet side of op-timum water content generally have a matrix-type structure with a monomodal pore size distribution(PSD),whereas soils compacted on the dry side of optimum water content display an aggregate structure that exhibits bimodal PSD.During drying,decrease in soil volume is mainly caused by the shrinkage of inter-aggregate pores.During wetting,both the intra-and inter-aggregate pores increase gradually in number and sizes.Changes in the characteristics of the soil pore structure significantly depend on stress state as the soil is subjected to wetting.During wetting/drying cycles,soil structural change is not completely reversible,and the generated cumulative swelling/shrinkage deformation mainly derives from macro-pores.Furthermore,based on this analysis and identified research needs,some important areas of research focus are proposed for future work.These areas include innovative methods of sample preparation,new observation techniques,fast quantitative analysis of soil structure,integration of microstructural parameters into macro-mechanical models,and soil microstructure evolution charac-teristics under multi-field coupled conditions.
基金This work is supported by the National Natural Science Foundation of China(51878116 and 51902270)Liaoning Province Key Project of Research and Development Plan(2020JH2/10100016)+1 种基金Dalian Science and Technology Innovation Fund Project(2020JJ26SN060)the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basins(China Institute of Water Resources and Hydropower Research),Grant No.IWHR-SKL-201910.
文摘In this paper,mercury intrusion porosimetry(MIP)is used to test the pore structure of non-dispersible underwater concrete so as to study the influence of pouring and curing environment,age and slag powder on the pore characteristics of concrete,analyze the pore characteristics,porosity and pore distribution of concrete in different hydration stages,and reveal the relationship between pore structure and permeability of concrete.The results show that the pore-size distribution of concrete in fresh water condition is better than that in sulfate environment and mixed salt environment,and therefore,sulfate as well as mixed salt are not conducive to the development of pore structure of non-dispersible underwater concrete;chlorine salt has little effect on the pore structure of nondispersible underwater concrete;under the three conditions of sulfate,chlorine and mixed salt,the porosity of concrete mixed with slag powder is lower than that of concrete without slag powder.The results indicate that the addition of slag powder can ameliorate the pore size distribution of non-dispersed underwater concrete,reduce the porosity,and make the concrete structure more compact,which is beneficial to improve the permeability resistance of concrete at the macro level.
文摘The building of the infrastructure on the compressible and saturated soils presents sometimes major difficulties. The infrastructure undergoes strong settlement that can be due to several phenomena of consolidation of the soils. The latter results from the dissipation of the excess pore pressure and deformation of the solid skeleton. Terzaghi theory led to the equation modeling the dissipation of excess pore pressure. The objective of this study is to establish solutions, by analytical and numerical method, of the equation of the pore water pressure. We considered a compressible saturated soil layer, between two drainage areas and subjected to a uniform load. Separation of variables is used to obtain an analytical solution and the finite element method for the numerical solution. The results obtained by the finite element method have validated those of analytical resolution.
文摘Pore water pressure has an important influence on mechanical properties of soil.The authors studied the characteristics of pore water pressure dissipating of mucky soil under consolidated-drained condition by using refitted triaxial instrument and analyzed the variation of pore pressure coefficient with consolidation pressure.The results show that the dissipating of pore water pressure behaves in different ways depends on different styles of loading.What is more,the pore water pressure coefficient of mucky soil is less than 1.As the compactness of soil increases and moisture content reduces,the value of B reduces.There is a staggered dissipating in the process of consolidation,in which it is a mutate point when U/P is 80%.It is helpful to establish the pore water pressure model and study the strength-deformation of soil in process of consolidation.
文摘In seasonal frozen soil region,the engineering geological properties of loess-like soil will be deteriorated after freeze-thaw cycles.Through the freeze-thaw cycle experiment of remolded loess-like soil,under different freezing temperatures,the authors carried out freeze-thaw cycle tests for 3 times and 20 times,respectively.With mercury intrusion porosimetry and granulometric analysis,from the micro-structure,the authors studied the law that freeze-thaw cycle times and frozen temperature effect on the variation of microscopic pore of loesslike soil.This result can provide theoretical basis for comprehensive treatment of problems in the construction of the project in seasonal frozen loess-like soil region.
基金This paper was financially supported by the National Natural Science Foundation of China(Grant No.41972285)the Youth Innovation Promotion Association CAS(Grant No.2018363)Key R&D projects of Hubei Province,China(Grant No.2021BAA186).
文摘Because of the cementation inherited from the parent rock,weathered granitic soil is usually susceptible to disturbance,which poses considerable challenges for laboratory characterization.The cone penetration test with pore pressure measurements has long been known for its reliability in site investigations and stratigraphic profiling.However,although extensive piezocone test results and experience are available for sedimentary soil,similar advances are yet to be made for weathered granitic soil.Moreover,the experience from sedimentary soil may not be directly applicable to weathered profiles because of the essentially different natures of the two types of geomaterials.This study performs seismic piezocone tests in a weathered granitic profile comprising residual granitic soil,completely weathered granite,and highly weathered granite.Pore pressure is measured at both the cone mid-face and the shoulder,and the effects of penetrometer size and penetration rate are considered.A series of updated soil behavior type charts is proposed to interpret the test results,thereby allowing the effect of weathering to be evaluated.This paper offers an important extension to the sparse data on the in situ responses of weathered materials.