中主应力对黄土变形强度特性影响的试验研究

Experimental Research on theEffect of Intermediate Principal Stress on Loess Deformation and Strength

对陕西杨凌黄土进行真三轴试验,采用了不同含水率和固结围压下对不同中主应力比b的应力路径进行试验,研究了中主应力比b对重塑黄土的变形和强度的影响规律。试验结果表明:在一定的含水率和固结压力下,偏差应力和初始切线模量均随中主应力比b的增大而增大;在中主应力比b确定的情况下,偏差应力和强度最大值随着含水率的增大而减小。小主应变ε3在任意条件下始终表现为膨胀;中主应变ε2随着固结压力和b的增大由膨胀变为压缩,固结压力越高,决定中主应变压缩的最小b值越小。

The effect of intermediate principal stress on loess deformation and strength characteristics with different water contents and consolidation pressures is studied by using true triaxial apparatus in 3-D stress state. It is found that in certain water ratios and consolidation pressures, the values of initial elastic modulus and principal deviator stress increase with intermediate principal stress increasing; in certain intermediate principal stresses, the values of initial elastic modulus and principal deviator stress increase with water ratio falling. Expansibility appears in the direction of minor principle stress all the time while the direction of intermediate principle stress turns out to be from expansibility to compressibility with consolidation pressure and intermediate principal stress increasing. The larger consolidation pressure and the smaller intermediate principal stress ratio decide the change.