k_(0)固结与等向固结三轴不排水抗剪强度研究

Experimental study on undrained triaxial shear strength of k_(0) and isotropic consolidated soil

为研究不同固结方式下土体不排水抗剪强度的差异,基于应力控制式三轴仪对饱和细粒土进行了k_(0)固结和等向固结三轴不排水压缩试验,结果表明:k_(0)固结三轴不排水抗剪强度为等向固结不排水强度的0.87倍,后者高估了土体实际强度,实际应用中可在比对试验基础上,通过等向固结三轴试验结果换算k_(0)固结不排水抗剪强度;等向固结、k_(0)固结三轴不排水标准强度随塑性指数增大呈减小趋势,分布于0.27~1.15之间。标准强度随着超固结比的增大而增大,正常固结或接近正常固结的黏土,其标准强度介于0.27~0.47之间,OCR大于2.2的超固结黏土,其标准强度大于0.50。

To analyze the difference of undrained shear strength of soil under different consolidation paths,a series of undrained triaxial compression tests of k_(0) and isotropic consolidated fine-grained soils were carried out using the stress-controlled triaxial apparatus.It is shown that the undrained triaxial shear strength of k_(0) consolidated soil is 0.87 times that of isotropic consolidated soil and the latter overestimates the actual strength of soil.The undrained shear strength of k_(0) consolidated soil can be converted from the results of isotropic consolidation triaxial tests based on comparison tests in practical application.The normalized undrained strength of isotropic and k_(0) consolidated soil decreases with the increase of plastic index,ranging from 0.27 to 1.15.The normalized strength increases with the increase of the over-consolidation ratio(OCR),which is between 0.27 and 0.47 for normally or nearly normally consolidated clay,and for over-consolidated soil with OCR greater than 2.2,the normalized strength is greater than 0.50.