某站场帮填路基失稳原因分析及整治措施

Cause Analysis and Treatment Measures of Instability of Side Filling Subgrade in a Station Yard

某站场帮填路基在完成基床底层和表层填筑后,坡脚反压护道及路基顶面多处出现贯通裂缝,严重影响帮填路基上方邻近的既有线安全运营。通过补充勘察和现场调查,结合边坡稳定性计算,厘清帮填路基致灾机理,并针对现场情况提出应急加固措施及治理方案。结果表明:新建邻线并行路基大坡度无支护基坑开挖造成帮填路基坡脚卸载临空,进而导致帮填路基边坡沿软弱结构面产生牵引式变形;邻线基坑无支护开挖导致边坡稳定系数由1.28降至0.93,不满足路基边坡稳定性要求;在既有线和帮填路基间设置钢板桩和帮填路基清方减载可作为临时应急加固措施;钢管桩联合注浆加固既有线边坡,帮填路基清方并与新建邻线同步开挖、同步回填可作为永久工程处理措施。经现场验证,整治措施安全有效,经济效益、社会效益显著。

After the completion of the filling of the bottom layer and surface layer of the subgrade of a station yard,there are many through cracks in the back pressure berm at the slope toe and the top surface of the subgrade,which seriously affects the safe operation of the adjacent existing line above the side filling subgrade.Through the supplementary investigation and field investigation,combined with the slope stability calculation,the disaster mechanism of side filling subgrade is clarified,and the emergency reinforcement measures and treatment scheme are put forward according to the field situation.The results show that the excavation of the foundation pit of the new adjacent parallel subgrade with large slope without support causes the unloading of the slope toe of the side filling subgrade,which leads to the traction deformation of the side filling subgrade slope along the weak structural plane;the excavation of the foundation pit of the adjacent line without support causes the slope stability coefficient to decrease from 1.28 to 0.93,which does not meet the stability requirements of the subgrade slope;setting steel sheet piles between the existing line and the side filling subgrade and removing earthwork and reducing load of the side filling subgrade can be used as a temporary emergency reinforcement measures.Steel pipe piles combined with grouting can reinforce the existing line slope,remove earthwork of the side filling subgrade,and excavate and backfill synchronously with the new adjacent line which can be used as permanent engineering treatment measures.It has been proved to be an effective treatment measure by field verification,and has good economic and social benefits.