Large-scale field shear tests on ten specimens of the red-sandstone embankment at a highway in Hunan,China,were performed to examine mechanical characteristics and parameters of red-sandstone.The curves of thrust-disp...Large-scale field shear tests on ten specimens of the red-sandstone embankment at a highway in Hunan,China,were performed to examine mechanical characteristics and parameters of red-sandstone.The curves of thrust-displacement,failure mode,and shear strength parameters for red-sandstone with different water contents,different compactions,and different grain size distributions were obtained from the tests.A practical procedure of in-situ test for red-sandstone embankment was proposed to normalize the test equipment and test steps.Based on three-dimensional thrust-sliding limit equilibrium method,the formulas for calculating strength parameters of red-sandstone considering three-dimensional sliding surface were inferred.The results show that red-sandstone has typical complete curves of stress-strain,strain softening,which are caused by the special structure of red-sandstone;water content and compaction are important factors for strength and failure mode of red-sandstone;The average value of cohesion and internal friction angle of the specimens calculated by three-dimensional technique are 21.56 kPa and 29.29°,respectively,and those by traditional two-dimensional method are 25.52 kPa and 33.76°,respectively.展开更多
As a widely distributed geological and engineering material,the soil-rock mixture always undergoes frequentative and short-term freeze-thaw cycles in some regions.Its internal structure is destroyed seriously,but the ...As a widely distributed geological and engineering material,the soil-rock mixture always undergoes frequentative and short-term freeze-thaw cycles in some regions.Its internal structure is destroyed seriously,but the damage mechanism is not clear.Based on the damage factor,the damage research of properties of soil-rock mixture after different times of freeze-thaw cycles is investigated.Firstly,the size-distributed subgrade gravelly soil samples are prepared and undergo different times of freeze-thaw cycles periodically(0,3,6,10),and indoor large-scale triaxial tests are completed.Secondly,the degradation degree of elastic modulus is considered as a damage factor,and applied to macro damage analysis of soil-rock mixture.Finally,the mesoscopic simulation of the experiments is achieved by PFC3D,and the influence on strength between soil-rock particles caused by freeze-thaw cycles is analyzed.The results show that freeze-thaw cycles cause internal damage of samples by weakening the strength between mesoscopic soil-rock particles,and ultimately affect the macro properties.After freeze-thaw cycles,on the macro-scale,elastic modulus and shear strength of soil-rock mixture both decrease,and the decreasing degree is related to the times of cycles with the mathmatical quadratic form;on the meso-scale,freeze-thaw cycles mainly cause the degradation of the strength between soil-rock particles whose properties are different significantly.展开更多
基金Project(200612) supported by Hunan Province Transportation Department of China
文摘Large-scale field shear tests on ten specimens of the red-sandstone embankment at a highway in Hunan,China,were performed to examine mechanical characteristics and parameters of red-sandstone.The curves of thrust-displacement,failure mode,and shear strength parameters for red-sandstone with different water contents,different compactions,and different grain size distributions were obtained from the tests.A practical procedure of in-situ test for red-sandstone embankment was proposed to normalize the test equipment and test steps.Based on three-dimensional thrust-sliding limit equilibrium method,the formulas for calculating strength parameters of red-sandstone considering three-dimensional sliding surface were inferred.The results show that red-sandstone has typical complete curves of stress-strain,strain softening,which are caused by the special structure of red-sandstone;water content and compaction are important factors for strength and failure mode of red-sandstone;The average value of cohesion and internal friction angle of the specimens calculated by three-dimensional technique are 21.56 kPa and 29.29°,respectively,and those by traditional two-dimensional method are 25.52 kPa and 33.76°,respectively.
基金Project(50908234)supported by the National Natural Science Foundation of ChinaProject(2017G002-K)supported by the Key Subject of Science and Technology Research and Development Plan of China Railway General Corporation
文摘As a widely distributed geological and engineering material,the soil-rock mixture always undergoes frequentative and short-term freeze-thaw cycles in some regions.Its internal structure is destroyed seriously,but the damage mechanism is not clear.Based on the damage factor,the damage research of properties of soil-rock mixture after different times of freeze-thaw cycles is investigated.Firstly,the size-distributed subgrade gravelly soil samples are prepared and undergo different times of freeze-thaw cycles periodically(0,3,6,10),and indoor large-scale triaxial tests are completed.Secondly,the degradation degree of elastic modulus is considered as a damage factor,and applied to macro damage analysis of soil-rock mixture.Finally,the mesoscopic simulation of the experiments is achieved by PFC3D,and the influence on strength between soil-rock particles caused by freeze-thaw cycles is analyzed.The results show that freeze-thaw cycles cause internal damage of samples by weakening the strength between mesoscopic soil-rock particles,and ultimately affect the macro properties.After freeze-thaw cycles,on the macro-scale,elastic modulus and shear strength of soil-rock mixture both decrease,and the decreasing degree is related to the times of cycles with the mathmatical quadratic form;on the meso-scale,freeze-thaw cycles mainly cause the degradation of the strength between soil-rock particles whose properties are different significantly.
