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利用GDS应力路径三轴仪测定了上海第(4)层软黏土的静止土压力系数K_0,并利用弯曲元测定了K_0状态下的土体剪切波速和最大剪切模量G0。同时,测定了等向固结应力状态下的剪切波速和最大剪切模量G0,建立了最大剪切模量G0和等向围压σ’_c的函数关系,推导出G0与静止土压力系数K_0的函数关系,并基于K_0状态下的G0值计算了静止土压力系数K_0,对比了三轴试验得到的K_0真实值及通过计算得到的K_0理论值,以研究利用最大剪切模量G0反算静止土压力系数K_0的可能性。试验研究表明,利用应力路径三轴仪测定K_0系数时,在达到设定围压后,需充分消散加载过程中的超静孔隙水压力来保证K_0值的准确性。同时,基于等向和K_0应力状态下的最大剪切模量G0的K_0反算值和实测值非常接近,这也为根据现场波速测试结合室内试验确定现场K_0提供了可行性。
The static earth pressure coefficient K_0 of the fourth layer of Shanghai clay was measured by the GDS stress path triaxial apparatus. The shear wave velocity and the maximum shear modulus G0 of the soil under K_0 state were measured by the bending element. At the same time, the shear wave velocity and the maximum shear modulus G0 were measured under the condition of isotropic consolidation stress. The relationship between the maximum shear modulus G0 and the confining pressure σ’_c was established, and the relationship between G0 and resting earth pressure Coefficient K_0, and calculated the static earth pressure coefficient K_0 based on the value of G0 in K_0 state, and compared the true value of K_0 obtained by triaxial test and the calculated K_0 theoretical value to study the relationship between the maximum shear modulus G0 Calculate the possibility of resting earth pressure coefficient K_0. The experimental results show that when the K_0 coefficient is measured by stress path triaxial apparatus, the excess pore water pressure during loading should be fully dissipated to ensure the accuracy of K_0 after reaching the set confining pressure. At the same time, the K_0 inverse calculation based on the maximum shear modulus G0 under the isotropic and K_0 stress is very close to the measured value, which also provides the feasibility to determine the K_0 field based on the on-site wave velocity test combined with the laboratory test.