既有铁路路基沉降变形原因分析及治理方案研究

Analysis and Mitigation of Adverse Settlement of Existing Railway Roadbed

为研究既有铁路路基沉降的原因及其治理方案,通过对工程地质条件分析,采用数值模拟高压旋喷桩加固路基施工全过程,提出了既有铁路路基沉降的原因和合理治理方案,并得出结论:(1)路基结构中填料与原地面各层间的渗透性差异较大时,若路基填方底部分布一层软弱层(粉土),该路基易产生沉降变形;(2)地下水位的上升将引起路基断面内软弱土层软化,导致软弱土层的压缩性增大,致使路基承载力下降;(3)高压旋喷桩在进行路基加固时,桩内侧角度选取25°时,加固效果较为明显;(4)当斜向高压旋喷桩的实施保证土体的置换率达到20%左右时,在既有线上对路基(堤)下沉病害的治理效果显著。

This paper presents a case history of adverse settlement evaluation of the existing railway roadbed and its mitigation details. The factors that could result in the roadbed settlement and feasible settlement mitigation method are briefly discussed. The process of using the jet grout mitigating the roadbed was also numerically simulated with the site-specific soil parameters. The following results are obtained: 1) if the significant permeability differences exist between the subgrade structure and the original soil, the presence of silty soils will likely induce in the differential settlement within the roadbed;2) the raise of groundwater will soften the subgrade soils and increase the compressibility of the subgrade soils and then result in additional settlement;3) When applying the jet grout method, the best result is at time the column jetting angle is 25 degrees;4) When the replacement ratio of the jet grout-soil is reached 20%, the best mitigation results can be obtained.