Red Clay Engineering Performance Test And Numerical Simulation

As a special terrigenous soil,red clay is widely distributed in the Yunnan-Guizhou Plateau and its adjacent areas in the central and western Guangxi.It has poor physical properties but rather good mechanical properties.As the main soil involved in the engineering construction in Guizhou,red clay is often used in such projects as construction foundations,water conservancy roads and slopes.Although the red clay in our country has some achievements in the research at present,its research depth and breadth are much deficient than that of other soils in strength and deformation.The research on strain softening and mechanical properties of red clay is not adequate as well.In this paper,the red clay in deep foundation pit of a city's Hengfeng Center was taken as the research object.The indoor triaxial compression tests were carried out on undisturbed and remolded soils with different water content.The unconsolidated undrained(UU),consolidated undrained(CU)),the stress-strain relationship and strength characteristics of undisturbed red clay under Consolidated Drainage(CD)test scheme as well as the influence of water content on the deformation and strength index of red clay were analyzed.It analyzed the stress-strain curves and strength,destruction of the characteristics of the differences as well.Taking the consolidation undrained test as an example,the stress-strain curve of undisturbed red clay was fitted by the nonlinear model of Nanjing Academy of Water Conservancy and its softening characteristics were discussed and the numerical experiment was carried out in FLAC3D software to provide a computational model for engineering application.The main contents include:1.The conventional physical and mechanical tests and triaxial compression tests on red clay were carried out.The test contents include the UU,CU,CD tests of the 59%,41%,35.2%and 31.5%water content of original soil,and the CU test of the remolded soil.Based on the test results,the stress-strain relationship and strength-deformation characteristics of undisturbed red clay under three test conditions were analyzed.The influence of moisture content on the stress-strain relationship,strength index and failure morphology of red clay was analyzed as well.2.According to the undrained test data of undisturbed red clay and remolded red clay with 41%water content,it is found that in the two states of soil,the stress-strain curve,shear strength,stress path,failure mode,pore water pressure and solidification knot displacement and other aspects are different,of which undisturbed soil showed softening properties,while the remolded soil was strain hardening characteristics.The original soil shear strength is greater than the remineralized soil.The undisturbed soil was cut and damaged,and the remodeled soil was drum-shaped and destroyed.It is preliminarily speculated that the structural difference caused by the irreversible stress history and the irreversibility of the drying of the red clay cements is the cause of the difference in strength and deformation of the two kinds of soils.3.Based on the non-drainage test data of intact red clay with a water content of 41%,the model parameters are calculated and the mathematical expressions of the stress-strain relationship of undisturbed red clay are obtained.According to the mathematical expression,the stress-strain curve of the softening model is drawn and compared with the test curve.The fitting curve of the model calculation curve and the test curve is high,which shows that the model can better express the softening property of the stress-strain curve of the undisturbed red clay.4.Established a standard cylindrical FLAC3D numerical test model,it took in the cohesion and internal friction angle calculated by the non-linear model of Nanjing Water Resources Institute into FLAC3D softening model to conduct the original red clay triaxial compression numerical test.The numerical test of the stress-strain curve and the test curve has a higher consistency,indicating that Nanjing Institute of Water Resources nonlinear model can accurately reflect the undisturbed red clay softening properties.