黄土节理抗剪强度特性试验研究

试验得出表面形态、干密度和含水量对黄土节理的强度特性的影响,揭示出黄土节理表面形态对抗剪强度参数c、φ值的影响规律。在相同含水量和干密度的情况下,粗糙表面的节理粘聚力c值较平整表面节理的大,而节理的摩擦角φ值相差较小,说明黄土节理形态特征对节理粘聚力c值有较大影响,而对摩擦角φ值影响较小。干密度对黄土节理粘聚力c值的影响较大,而对内摩擦角φ值的影响较小。当试样含水量在一定范围之内,黄土节理的摩擦角随含水量的增加呈二次曲线变化。但当试样含水量较大时,测得试样抗剪强度稍有增大,是因为节理表面部分土体在法向压力作用下发生重塑,破坏面已不是原有节理面,重塑土体自身的抗剪强度发生作用,引起试验所测抗剪强度的增大。

Experimental Research on Shear Strength of the Loess Joints

An experiment has been carried out to oscertain the influence of surface contours, dry density and water content of loess on the loess joint intensity characteristic and reveal the rule of the influence of loess joint surface contours on the value of shear strength parameters c and φ. Under the same water content and dry density situation, the value of cohesive force c for rough surface joint is greater than that for smooth surface joint, but the change of the value of internal friction angle φ for the loess joint is small. It shows that the loess joint’ surface contour has great effect on the value of joint cohesive force c, but less effect on the value of the internal friction angle φ. The dry density has great effect on the value of joint cohesive force c, but less effect on the value of the internal friction angle φ. When the water content of test specimen is in a certain range, with the increase of water content, loess joint’ internal friction angle changes with a quadratic relationship; when the test specimen water content increase greatly, the experiment showed that the shear strength had only a slight increase, because partial soil body on the loess joint surface remolded under the normal pressure, the failure plane was already not the original joint plane, the shear strength of the remolded soil caused the increase of shear strength of the loess joint in the test.