川西全强风化卵石土边坡稳定性影响因素分析

Analysis on Factors Influencing Stability of Fully Weathered Pebble Soil Slopein Western Sichuan

研究目的:四川西部地区分布大量的全强风化卵石土(Q_(2)、Q_(3))地层,该类边坡遇水易软化失稳,出现垮塌、溜坍等灾害。以川西铁路典型边坡工程为依托,利用颗粒流数值模拟分析该类边坡破坏及发展的全过程动态问题,研究坡率、坡高、含水率三种因素对边坡稳定性的影响,获得敏感性顺序,提出边坡设计时坡率、坡高的控制建议,为风化卵石土地层的边坡工程建设提供技术支撑。研究结论:(1)全强风化卵石土边坡整体失稳时符合牵引式滑动特征,滑体呈现散体状;(2)该类边坡稳定性因素敏感性顺序为:坡率>坡高>含水率,当坡率由1∶1.5增加至1∶0.75时,边坡稳定性系数降幅达1.9,含水率由14%增加到16%时,软化作用明显,坡高较小时边坡更稳定;(3)建议边坡设计时,坡率小于1∶1.25,坡高控制在8 m以下,并做好防排水措施,使边坡含水率控制在14%以下;(4)本研究可为川西地区全强风化卵石土边坡稳定性分析和防护设计提供依据。

Research purposes:There are a large number of fully weathered pebble soil(Q_(2),Q_(3))formations in the west Sichuan region,which are prone to instability,collapse and slide when encountering water.Based on the slope engineering of west Sichuan region railways,the dynamic problems of the whole process of slope failure were analyzed and the influences of slope rate,slope height and water content for slope stability were considered with particle flow code.According to the influence of property,the sensitivity order is obtained,and the control suggestions of slope ratio and slope height are put forward in slope design,so as to provide technical support for the construction of slope engineering in weathered pebble soil layer.Research conclusions:(1)The characteristics of failure for fully weathered pebble soil slope were completely in accord with pull-type slip,landslide body was dispersed.(2)The sensitivity order of influencing factors on stability is as follows:slope rate>slope height>water content;the stability factor of slope decreased by 1.9 with that slope rateincreased from 1∶1.5 to 1∶0.75,the safety factor decreased by 0.5 as a result of being softened with that the water content increased from 14%to 16%,the slope was more stable with low height.(3)It was recommended for slope design that the slope rate needed to be less than 1∶1.25,the slope height should be controlled below 8 m,and waterproof-drainage measures had better be taken to control water content under 14%.(4)The study can provide corresponding references for stability analysis and protection design of fully weathered pebble soil slope for west Sichuan region.