膨胀土裂隙面抗剪强度及影响因素试验研究

EXPERIMENT STUDY OF SHEAR STRENGTH OF CRACK SURFACE AND ITS INFLUENCING FACTORS FOR EXPANSIVE SOIL

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。

Fissure is one of important feature of expansive soil in different from other clays, which has control action on the shear strength and stability of expansive soil slope. The original expansive soil was chosen from Handan section of the middle project for South-to-North Water Transfer as samples for the strength of crack surface to make direct shear tests for in-situ soil samples with straight crack surface, and also to triaxial tests of irrrgular crack surfaces, for further test results were compared with repeated shear ones of original expansive soil without crack. On the basis of original soil research test, it was explored the influence of single angle of crack surface and filled clay thickness in remodling soil samples on shear strength by simulation of the crack surface. According to the results, the high moisture content and montmorillonite content and the directional arrangement of parcticles of the grayish-white clay that filled in the crack, made the strength of crack surface be much lower than the peak strength of yellow expansive soil without crack on each side, and closed to its residual strength. The strength of crack surface was decreased with the increase of crack angle （30° - 60°） and thickness of the filled clay, and the influence of angle of the crack surface was more obvious.