Study On The Engineering Characteristic Of Light Heterogeneous Soil Mixed Expanded Polystyrene

Being a new kind of light filling materials, Lightweight Soil Mixed with Expanded Polystyrene(hereafter as LSM-EPS) has been developed as a new technique for foundation treatment at present(Patent No.:02112812.X).It has different characteristics from conventional soil materials. Based on laboratory tests, the physics, strength and deformation characteristics of LSM-EPS are studied deeply in this paper in the view of the application in engineering. In concrete, it includes the works as follows:(1) Based on testing the density of the LSM-EPS at different mixing proportion, its density change rule varied with mixing proportion is obtained. The results of tests indicate that the content of expanded polystyrene grains is the main influence factor to the density of LSM-EPS. The cement-mixed ratio, water content and the properties of soil also have some influences to it. 7 days later, the density is almost independent of the age. The testing methods, curing conditions and so on have some influence to the density. That should be paid attention to during the test. It has a comparative significance to study the change rule of density of LSM-EPS with different cement-mixed ratio, water content, EPS grains content, and age and so on for adjusting the required density.(2) Based on unconfined compressive tests and triaxial shear tests, the stress-strain properties of LSM-EPS are analyzed. The results indicate that the uniaxial stress-strain curves are affected by cement mixed ratio, water content, density and age at various degrees. That means the properties of stress-strain are influenced by mixing proportion apparently. The stress-strain properties of the UU test and CU test are different with the different mixing proportion and ages.( 3 ) The simulation of stress-strain curves. The uniaxial and triaxial stress-strain curves are simulated .The results indicate that a hyperbolic model and strain softening model can reasonably simulate the stress-strain relations under uniaxial stresses conditions and a elastic-linear hardening model can reasonably simulate the stress-strain relations under triaxial stresses conditions. It can be made the base for constitutive model of LSM-EPS.(4) The influence factors for failure strain and deformation modulus of LSM-EPS are analyzed. Tests results demonstrate that failure strain changes with the change of cement mixed ratio, water content, density, age and has a linear relation with the compressive strength, while deformation modulus and compressive strength have the same relation. Deformation modulus is decreased with the increasing of confining pressure in the triaxial compression test. It's main for finding out the failure mode and acquiring the deformationcalculation parameters of mixed soil.(5) Compression deformation characteristic of LSM-EPS is analyzed according to uniaxial consolidation compression tests. Test results show that cement mixed ratio, density, water content, and age have an influence on compression deformation characteristic in different level. On this base, the compressive yield stress and compressive deformation modulus of LSM-EPS are confirmed, which provide the gist for controlling the deformation quantity of LSM-EPS during engineering. The relation between deformation and time of mixed soil during compression is made a pilot study. It takes for that most of the deformation of mixed soil is finished momently.(6) The change rule of compressive strength for LSM-EPS is analyzed. Firstly, the rule of uniaxial compressive strength changing with cement-dosage, water content, density and age is analyzed, which provide the basis for determining the mixing proportion according to the aim strength. After conversion between the cement mixed ratio and the cement content, the experienced calculation formula are obtained, which are convenient for engineering application. The main influence factors to the compressive strength of LSM-EPS are considered synthetically. Results show that cement content is the mostly influence factor to the compressive strength of LSM-EPS, and...