剪切应变速率对淤泥土力学性状影响试验研究

为研究剪切应变速率对高含水量淤泥土力学性状的影响,运用SPAX-2000真三轴测试系统进行了不同周围压力和不同应变速率的固结不排水剪切试验,分析了淤泥土不排水抗剪强度和孔隙水压力随应变速率的变化规律。试验结果表明,高含水量淤泥具有“应变速率软化”现象。在剪切过程中(应变速率为10^-6/s～10^-2/s),淤泥土不排水抗剪强度随剪切应变速率增长而增长,符合指数变化规律;根据试验数据,建立了经验方程式,并求得其应变速率参数η_e1为0.130 5,η_e2为0.131 9;当变率增长10倍时,淤泥土的不排水抗剪强度增长率为13.12%。不同于强结构性黏土,淤泥土的强度随剪切应变速率呈渐进性变化,未出现明显临界速率转折点。在加载初期,孔隙水压力增长和最大孔隙水压力受应变速率影响较明显;在试验过程中,孔隙水压力变化具有一定波动性和滞后性。

Experimental Study on Effects of Shear Strain Rate on Mechanical Behavior of Muck Soil

In order to investigate the effects of shear strain rate on mechanical behavior of high water content muck soil based on SPAX-2000 test system, a series of true triaxial consolidation undrained shear tests were carried out under different confining pressures and different strain rates, variation rules of undrained shear strength of muck soil and the pore water pressure with strain rate were analyzed. The experimental results indicate that strain rate softening exists in muck soil. Under the experimental conditions (the strain rate ranges from 10^-6/s to10^-2/s), the undrained shear strength of muck soil increases with the increase of strain rate, the exponential rate equation can reflect relationship between the undrained strength and strain rate of muck soil. The empirical equations were established based on test data, the rate parameters η_e1 is 0.130 5 and η_e2 is 0.1319. When the strain rate increases 10 times, the growth rate of undrained shear strength is 13.12%. Different from strong structural clay, the shear strength gradually increases with the strain rate of muck soil without significant critical rate. The initial pore water pressure increase and the maximum pore water pressure are greatly affected by the strain rate. Another obvious feature of the pore water pressure is fluctuating and lagging.