土石混合体边坡细观特征对滑面形成影响研究

EFFECT OF MICRO CHARACTERISTICS OF SOIL-ROCK MIXTURE SLOPE ON FORMATION OF SLIDING SURFACE

土石混合体是由软弱的土颗粒与刚度较大、强度较高的块石混合而成,因此土石混合体边坡失稳时,其滑动面受块石-土形成的细观结构特征影响,导致边坡稳定性分析存在诸多困难。本文基于一典型的土石混合体边坡,建立颗粒离散元数值模型,通过室内试验标定土体细观参数,结合强度折减法分析土石混合体边坡与纯土体边坡破坏模式及滑面形态的差别。结果表明:块石的存在使得土石混合体边坡的接触力链分布极不均匀,块石的存在使接触力链形成闭环,增大了滑动面积,对边坡有加固作用;土石混合体边坡的滑面发展趋势总倾向于穿过块石间的缝隙,滑面的发展与块石分布状况相关联;当块石含量达到20%以上时,边坡稳定性显著提高;块石含量达到30%~50%时,滑坡以局部块体运动为主,无法形成连续的滑动面。研究成果可为土石混合体边坡的变形破坏机理分析提供依据与参考。

As the mechanical properties of soil-rock mixture are complicated,the sliding surface of soil-rock mixture slope is affected by its microstructure characteristics.We established a typical soil-rock mixture slope model with particle discrete element method.The servo mechanism was applied to construct a numerical model with homogeneous stress.Then we calibrated the microparameters of contact model based on the laboratory test data.Combining the strength reduction method,we analysed the difference of the sliding surface morphology between the soil slope and soil-rock mixture slope.The results show that the existence of the block stone causes the nonuniform distribution of the contact force chain,and the block stone increases the slope stability.The development of the sliding surface tends to pass through the gaps between the blocks and is related to the location of block stone.Slope stability is closely related to rock content.As the content of rock reaches 30%~50%,the landslide is dominated by the movement of local block and cannot form a continuous sliding surface.The study provides the reference for the analysis of failure mechanism of soil-rock mixture slope.