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通过水泥土平面应变试验和三轴压缩固结排水试验(CD试验),对水泥土力学特性进行研究,讨论两种试验条件下水泥土的应力-应变曲线变化特点和强度特性。试验结果表明,水泥土的应力-应变曲线为软化型,软化程度与围压有关,平面应变条件下水泥土软化明显;CD试验和平面应变试验的强度破坏线均为直线,可用摩尔-库仑强度准则来描述;两种试验条件下的残余强度均随围压的增加呈线性增大,其中平面应变试验残余强度高于CD试验,残余强度与峰值强度的比值随围压的增大而增大,增大速率减小;平面应变条件下,水泥土的破坏强度约为三轴CD试验的1.4～1.6倍。从微观结构和能量守恒原理解释了CD试验和平面应变试验水泥土软化成因,认为水泥水化物等凝胶材料是水泥土软化的主要因素,且中主应力的存在使水泥土软化更加明显。
The mechanical properties of cemented soil are studied by the plane strain test of cement soil and the three-axis compression consolidation drainage test (CD test), and the stress-strain curve change characteristics and strength characteristics of cemented soil under two test conditions are discussed. The test results show that the stress-strain curve of cement-soil is softening-type, and the degree of softening is related to confining pressure. The cement-soil softens significantly under the condition of plane strain. The strength failure curves of CD test and plane-strain test are straight lines. The residual strength of the two kinds of test conditions increases linearly with the increase of confining pressure. The residual strength of plane strain test is higher than that of CD test. The ratio of residual strength to peak strength increases with the increase of confining pressure, The rate of increase decreases; under the condition of plane strain, the failure strength of cement soil is about 1.4 ~ 1.6 times of that of triaxial CD test. From the microstructure and energy conservation principle, the causes of CD softening and soil softening of CD test and plane strain test are explained. It is considered that the cement material such as cement hydrate is the main factor of softening of cement soil, and the softening of cement soil is more obvious with the presence of main stress.