Experimental Study On Dynamic Characteristics Of Red Sandstone Soil In South Jiangxi Province

Red sandstone soil is widely distributed in Jiangxi and other regions,and it is widely used in engineering construction.Red sandstone soil is more special than other soils.It has the characteristics of easy softening,disintegration,and large changes in strength when exposed to water,which can easily cause some problems in engineering.At present,there are many researches on the physical and static characteristics of red sandstone soil,but there are few reports on its dynamic characteristics.In recent years,the engineering construction of Ganzhou is very large.There are many problems with dynamic characteristics in construction,so it is important to study the dynamic characteristics of red sandstone soil.Experimental study on dynamic characteristics of red sandstone soil is based on the “Three-dimensional minimum potential energy analysis method for dynamic stability of slope under earthquakes”(No.20151BAB206026).The main working contents of this paper are as follows:(1)Through a series of soil mechanics tests,some basic physical and mechanical indicators of red sandstone soil had been measured.These parameters provided reference for subsequent analysis of dynamic characteristics.(2)The GDS Dynamic Triaxial Test System was used to test the red sandstone soil step by step.The dynamic stress-dynamic strain relationship of red sandstone soil under different consolidation conditions was analyzed.The dynamic stress-dynamic strain was based on the Hardin-Drnevich viscoelastic model.The curve was fitted and the relevant parameters in the model were obtained.(3)Based on the dynamic stress-dynamic strain relationship of red sandstone,the dynamic elastic modulus was calculated.By analyzing the dynamic elastic modulus with dynamic strain,the relationship between dynamic elastic modulus and dynamic strain was established.According to the fitting result of dynamic stress-dynamic strain,the maximum dynamic elastic modulus formula of red sandstone soil was obtained.The maximum dynamic shear modulus was obtained using the relationship between dynamic axial strain,dynamic shear strain,elastic modulus,and shear modulus.Using the formula of equivalent damping ratio in soil dynamics,the relationship between damping ratio and dynamic strain of red sandstone soil was obtained.(4)A single-stage loading test of red sandstone soil was performed using a GDS dynamic triaxial test system.The hysteretic curves of soil under different consolidation conditions were compared and analyzed.Taking the axial dynamic strain as 5% as failure criterion,the dynamic strength curve and dynamic stress ratio curve of red sandstone soil under different consolidation conditions were obtained.The variation law of dynamic strength and dynamic stress ratio of soil was analyzed,and the fitting relation of dynamic strength was given.According to the dynamic strength curve,the dynamic shear strength index of red sandstone soil was obtained,and the relationship between the dynamic shear strength index and the failure time was analyzed.(5)The stiffness-softening characteristics of red sandstone soil were studied.The effects of consolidation conditions and loading conditions on the stiffness softening characteristics were analyzed.A stiffness-softening model of red sandstone soil was established,and the softening parameters under isotropic consolidation conditions were obtained through fitting.