考虑剩余剪应力的滑带土强度再生试验

用改造的直剪仪研究了滑带土再生强度与滑动面剩余剪应力比PRSS和强度再生时间的关系。结果表明,滑带土强度再生与上覆滑体压应力关系不大,但较高的剩余剪应力比PRSS妨碍滑带土强度再生,滑带土强度有效再生的界限PRSS在55%到70%之间。剩余剪应力比PRSS小于等于55%时,90 d时滑带土再生强度可达到慢剪强度的70%以上,PRSS大于等于70%时,90 d时滑带土再生强度不足慢剪强度的25%。滑带土强度再生过程中,黏聚力和内摩擦角增速不一致,PRSS小于等于55%时,黏聚力C在前30 d增速较快,30 d时增至慢剪强度C]的44.6%,此后增速均明显放缓,90 d时其值为慢剪强度C]的49%。内摩擦角φ在前90 d增速基本一致,90 d时其值占慢剪强度φ]的90.4%。黏聚力和内摩擦角90 d以后均趋于稳定。

Experimental study on strength regeneration of slip zone soils considering residual shear stress

The relationship between the percentage of residual shear stress(PRSS)and the time required for strength regeneration of slip zone soil was explored through a modified direct shear apparatus.The experimental results show that normal stresses has no direct effect on the strength regeneration of slip zone soil,but excessive residual shear stress hinders the strength regeneration.the corresponding threshold of effective strength regeneration of slip zone soil ranges from 55%to 70%.When PRSS≤55%,the strength regeneration of slip zone soil is greater than 70%of the slow shear strength at 90 days;when PRSS≥70%,the strength regeneration of slip zone soil is less than 25%of the slow shear strength at 90 days.During the processes of strength regeneration of slip zone soil,cohesion and internal friction angle increased with different speeds.When PRSS≤55%,cohesion C increased rapidly in the first 30 days,which would account for 44.6%of slow shear strengthC]at 30 days,then decreased significantly,and accounting for 49%of shear strengthC]at 90 days.The growth rate of internal friction angleφin the first 90 days is almost identical,at 90 days,its value accounts for 90.4%of the slow shear strengthφ].Cohesion and internal friction angle tends to be stable after 90 days.