锁儿头滑坡滑带土不同含水率大剪试验研究

锁儿头滑坡属特大型断层破碎带滑坡。该滑坡滑带土主要由强风化的中、上志留统千枚岩、板岩等构成，滑带土中粒径大于2 mm的颗粒含量约为30%，在滑带土颗粒组成中占有重要地位，其强度特征对滑坡体的稳定性分析具有重要影 响。为此，利用室内大型直剪仪对不同含水率下锁儿头滑坡滑带土的剪切特性进行试验研究，结果表明，在控制干密度为1.7 g/cm3情况下，不同含水率滑带土试样的剪应力-应变关系均呈现出弱应变硬化特征，而且法向压力越大，应变硬化特征越明显；在剪应变ε为10%时，相同含水率下滑带土剪切模量G0.1随法向压力的增大而增大，同一法向压力下的剪切模量G0.1与含水率间呈负线性相关关系；利用邓肯-张双曲线模型对锁儿头滑坡滑带土不同含水率下大剪试验剪应力-应变关系进行数据拟合，拟合效果良好，但该模型不能反映土的应变软化性质。

Experimental study of large scale direct shear test of sliding zone soil of Suoertou landslide with different moisture contents

Suoertou landslide which originated in fault rupture zone is a super large landslide, the sliding zone soil of the landslide consists primarily of highly weathered phyllite and slate in the Middle-Upper Silurian. There is about 30% amount of coarse particles of which size is greater than 2 mm in sliding zone soil; so the coarse particles occupy an important position in the soil particle composition and have serious influence on the stability of the landslide. The large scale direct shear apparatus is used here to investigate the direct shear strength behavior of the sliding zone soil under different moisture contents. The results show that there is a strain-hardening feature in the curve of the relationship between shear stress and shear strain with different water contents when the controlled dry density equals 1.7 g/cm3; besides, the more is the normal stress, the more is the hardening feature. The shear modulus G0.1 which is the modulus when the horizontal shear strain is 10% increases with the increment of normal stress at the same moisture content, and the shear modulus has a negative linear relation with moisture content at the same normal stress. The relationship between shear stress and horizontal shear strain can be simulated well by using Duncan-Chang hyperbolic model; but it can't reflect the strain softening feature of the sliding zone soil.