地震荷载下高含冰量冻土的动力特性试验研究

地震荷载作用下高含冰量冻土的动力特性试验研究对西北地区地震多发地段的冻土工程的抗震设计具有重要意义。通过选取兰州的重塑冻土进行动三轴试验,分别研究了地震荷载下不同控制温度(-6,-3,-1℃)、不同含水量(30%,50%,75%)以及不同围压(0.3,0.5,1,2 MPa)下高含冰量冻土的动应力应变关系和动弹性模量。试验结果显示,不同条件下冻土的动应力应变关系呈Hardin-Drnevich双曲线模型,并且不同温度、不同围压和不同含水量对模型参数都有着影响。动弹性模量随温度升高而减小,温度每升高1℃,弹性模量就下降12～15 MPa。围压对动弹性模量的影响有强化作用和弱化作用,-6℃时动弹性模量随围压增大而增大,-1℃时大应变情况下动弹性模量随围压增大而减小。对于高含冰量冻土,动弹性模量随含水量的增大先减小后增大。

Experimental Study on Dynamic Characteristics of Ice-rich Frozen Soil under Earthquake Load

Experimental study on dynamic characteristics of the ice-rich frozen soil under seismic load is of great significance to the seismic design of permafrost engineering in earthquake-prone areas in Northwest China. This paper conducts a dynamic triaxial test by selecting remolded frozen soil in Lanzhou and studies the dynamic elastic modulus and dynamic stress-strain relationship of the ice-rich frozen soil subject to different control temperatures(-6,-3,-1 ℃), different water contents(30%, 50%, 75%) and different confining pressures(0.3, 0.5, 1, 2 MPa) under seismic load. According to the test results, the stress-strain relationship tends to be a Hardin-Drnevich hyperbolic model, and the model parameters are influenced by different temperatures, different confining pressures and different water contents. The higher the temperature, the smaller the dynamic elastic modulus. For every 1 degree increase in temperature, the elastic modulus drops by 12～15 MPa. The influence of the confining pressure on dynamic elastic modulus has strengthening and weakening effect, the dynamic elastic modulus increases with the increase of confining pressure at-6 ℃, and the dynamic elastic modulus decreases with the increase of confining pressure at-1 ℃ under large strain. For ice-rich frozen soil, the dynamic elastic modulus decreases first and then increases with the increase of water content.