考虑加载速率影响的冻结含盐砂土强度准则研究

围压、加载速率等外部条件对冻结盐渍土强度影响显著。对-15℃德令哈含盐砂土进行了一系列不同加载速率、不同围压下的常规三轴剪切试验,依据广义非线性强度理论建立了考虑加载速率影响的冻结含盐砂土强度准则。依据试验结果采用二次函数拟合得到了子午面上的破坏函数,分析了加载速率对冻结含盐砂土强度及内摩擦角的影响。通过修正的Lade-Duncan强度准则给出了?平面上的破坏函数,探讨了加载速率对子午面破坏函数及偏平面形状函数的影响。提出的模型能够反映在加载速率、压融以及冰晶破碎等因素共同影响下的冻结含盐砂土强度的非线性特点。

Strength criterion for frozen saline sand considering effects of loading rates

The external conditions such as confining pressures and loading rates have significant influences on the strength of frozen saline soil. A series of conventional triaxial compression tests under different loading rates are carried out for Delingha frozen saline sand at a temperature of -15℃ with the confining pressures varying from 0.5 to 8 MPa. A strength criterion for the frozen saline sand, including the influences of loading rates, is established by use of the generalized nonlinear strength theory. Based on the conventional triaxial compression test results, the strength function in p-q plane is well fitted by the parabolic equation, and the relationship between loading rates and friction angles is analyzed. The strength function in π plane derived from the modified Lade-Duncan model considering the influences of loading rates and hydrostatic pressures is used. The proposed strength criterion can reflect the nonlinear strength characteristics of frozen saline sand, including the influences of change in the loading rates, pressure melting and ice crushing.