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裂隙性是膨胀土区别于其他黏土的重要特性之一,裂隙对其自身的抗剪强度及边坡稳定具有控制作用。以邯郸南水北调中线工程段原状膨胀土为试样进行裂隙面强度试验,选取平直裂隙面的原状样开展直剪试验,并通过三轴试验对不规则形态的裂隙面剪切进行完善,同时与不含裂隙原状土样的反复直剪成果对比;在原状样基础上通过人工模拟裂隙面的方法进一步探究单一裂隙面倾角和充填黏土厚度对抗剪强度的影响。结果表明:裂隙间灰白色黏土的性质和组成等异于两侧土,其高含水率、高蒙脱石含量以及颗粒的定向排列等,导致膨胀土裂隙面强度远低于两侧无裂隙黄褐色膨胀土的峰值强度,接近残余强度;裂隙面强度随着裂隙倾角(30°~60°)和充填黏土厚度的增加而减小,裂隙面倾角的影响表现得更为突出。
Crack is one of the most important characteristics of expansive soils that are distinct from other clays. Cracks have a controlled effect on their own shear strength and slope stability. In order to test the strength of the cracked surface with the original expansive soil in the middle section of the South-to-North Water Diversion Project in Handan, direct shear tests were carried out on the original samples of the flat crack surface. The triaxial tests were performed to improve the shear fracture of the irregular shape. The comparison of the results of repeated direct shear tests on the intact crack-free soil samples was carried out. Based on the original samples, the influence of single crack plane inclination and the thickness of filled clay on the shear strength was further studied by simulating the fracture surface. The results show that the nature and composition of the off-white clay are different from those on both sides. The high water cut, the high montmorillonite content and the directional arrangement of the particles lead to the fracture surface strength of the expansive soil being much lower than that on both sides The peak strength of the expansive soil is close to the residual strength. The strength of the fracture surface decreases with the increase of the fracture angle (30 ° -60 °) and the thickness of the filling clay. The effect of the fracture surface inclination is more prominent.