川东天台乡滑坡滑带特征及其工程意义

SLIP ZONE BEHAVIOR OF TIANTAIXIANG LANDSLIDE IN EAST SICHUAN PROVINCE AND ITS ENGINEERING SIGNIFICANCE

天台乡滑坡是川东典型的缓倾角红层基岩滑坡,对其滑带特征进行详细的研究有助于揭示缓倾角红层基岩滑坡的形成机制。物理性质实验证明,天台乡滑坡滑带土为可塑粉质黏土。X射线衍射分析表明,天台乡滑坡滑带土主要矿物成分为绿泥石、伊利石、石英、长石与方解石;扫描电镜观察发现,滑带土微观结构以片状结构与定向排列结构为主,微孔隙发育。作滑带土的直接慢剪试验,获得强度为:c=9.2～10.7kPa;=10.4°～12.3°;作滑带土三轴固结排水蠕变试验,获得蠕变强度为:c∞=18.1kPa;∞=8.0°。天台乡滑坡滑带滑带土中绿泥石和伊利石含量多,导致滑带的抗剪强度与蠕变强度低,是天台乡滑坡产生的主要内因。

The Tiantaixiang landslide is one of the typical gently dipping translational rock slides forming in the red beds in east Sichuan province.In order to discover the mechanism of these landslides,the slip zone behavior of Tiantaixiang landslide is studied in detail.Physical property tests show that the slip zone soil is plastic silty clay.The X-ray diffraction analysis reveals that the main mineral components of the slip zone are composed of chlorite,illite,feldspar,quartz and calcite.The results of scanning electron micrograph display that the microstructures of the slip zone are mainly sheet crystals and directional crystal structures,and micro pores developed well.Consolidated slow direct shear tests are conducted on the slip zone specimens.The results are c=9.2～10.7kPa and φ=10.4°～12.3°.Triaxial consolidated drained creep tests are conducted on the slip zone specimens to obtain the creep strength.The results show that the creep strength are c∞=18.1kPa and φ∞=8.0°.The large amount of chlorite and illite in the slip zone resulting in low shear strength and low creep strength is the main inner factor contributing to the sliding.