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利用电动应变控制式直剪仪及直剪/残余剪切试验仪对南水北调磁县段不同黏粒含量的原状膨胀土进行快剪、饱和快剪、饱和固结快剪和反复直剪试验,研究黏粒含量对其抗剪强度的影响。研究表明:饱和后试样的抗剪强度明显降低,固结后强度提高,且饱和作用对黏粒含量较大的中膨胀土强度的削弱作用更为显著,固结作用对黏粒含量较小的弱膨胀土强度的“治愈”作用更显著;随黏粒含量的增大,黏聚力逐渐减小,内摩擦角则先减后增,其临界值在32%左右;峰值强度后的抗剪强度降低幅度随黏粒含量的增加而增大;土体的峰值强度τf随黏粒含量则先减后增,变化趋势比较平缓;残余强度τr随黏粒含量增加逐渐减小,成指数关系;残余强度内摩擦角φr与黏粒含量成对数关系,黏聚力cr则比较离散。
The rapid shear test, fast shear test, fast shear test and repeated direct shear test of intact expansive soils with different clay content in the Cixian section of South-to-North Water Diversion Project were carried out using the electric shear-controlled direct shear and the direct shear / residual shear tester Effect of clay content on its shear strength. The results show that the shear strength of the sample after the saturation decreases obviously, the strength increases after consolidation, and the saturation effect weakens the strength of the middle expansive soil with larger clay content. The consolidation effect is less on the clay content The strength of the weak expansive soil is more “cured”. With the increase of the clay content, the cohesion decreases and the internal friction angle decreases first and then increases. The critical value is about 32% Shear strength decreases with the increase of clay content; soil peak strength τf with the clay content then decreased first increase, the trend is relatively flat; residual strength τr decreases with the clay content increases, into Exponential relationship; residual strength of the friction angle φr and clay content logarithmic relationship, cohesion cr is more discrete.