临近既有铁路增建新线地基处理施工影响比较分析

Comparison analysis of the impact of soft ground improvement construction on existing railways near newly constructed lines

我国东南沿海一带,铁路既有线的建设时代久远、铁路路基建设标准低,地基土质条件差,受增建新线铁路路基的地基处理施工影响明显。对地基处理施工进行现场监测,选取施工影响小的地基处理方法对保障既有铁路运营安全至关重要。根据超孔隙水压力、地表位移和深层位移的现场施工监测数据,分析地基处理施工影响范围和程度,得到以下结论:(1)施工影响由大到小的排序为高压旋喷桩(管桩)>水泥搅拌桩>全方位高压喷射(MJS)桩>布袋桩;(2)水泥搅拌桩施工影响范围在5 m左右,高压旋喷桩施工影响范围高达10 m,布袋桩施工影响范围大约为3 m,MJS桩施工影响范围在4 m左右。对比高压旋喷桩、管桩、布袋桩和MJS桩与搅拌桩施工影响大小,优化临近既有铁路增建新线的地基处理方案,可以有效控制增建新线地基处理对既有铁路的扰动影响,确保既有铁路安全。

In the southeast coastal area of China,existing railway lines,constructed long ago with low construction standards for railway subgrades,face significant impacts from the construction of soft ground improvement for newly built railway lines.Through on-site monitoring of foundation treatment construction,it is crucial to select the soft ground improvement method with minimal construction impact to ensure the operation safety of the existing railway.Based on the on-site monitoring data of the excess pore water pressure,surface displacement,and deep displacement in the construction of soft ground improvement,the study assesses the extent and magnitude of construction impact.The key findings include:(1)Ranking of construction impact magnitude:High-pressure jet grouting column(pipe pile)>deep cement mixing column>MJS column>geosynthetic reinforced column;(2)Construction impact range:deep cement mixing column,high-pressure jet grouting column,geosynthetic reinforced column and MJS column are about 5 m,10 m,3 m and 4 m,respectively.The construction disturbance of high-pressure jet grouting pile,pipe pile,polymer bag grouting pile and deep cement mixing column are compared based on the differences of excess pore water pressure,surface displacement,deep displacement and construction disturbance range.It is provided a basis for comparison and selection of schemes for soft ground improvement of new railway lines adjacent to existing railways.This optimization effectively controls the construction disturbance of the soft ground treatment of the new line and ensures the safety of the existing railway.