地下交叉工程下穿有轨电车路基的影响分析

地铁正线及竖井横通道交叉工程下穿有轨电车路基属于重要风险源,其空间位置关系复杂,区间、横通道施工均会对有轨电车路基产生影响,且影响时机及程度很难判定。为此,基于数值分析方法对交叉工程下穿有轨电车路基施工全过程进行模拟,评价交叉工程建设过程中及建成后对既有有轨电车路基的影响情况。计算结果表明,下穿段落横通道采用四台阶法、双排小导管超前加固,区间采用上下台阶法、单排小导管超前加固,能有效控制有轨电车路基沉降并保证有轨电车运营安全;横通道垂直下穿阶段对有轨电车路基沉降影响最大,占总沉降的46.6%;路基倾斜(不均匀沉降)最大值发生在区间3开挖完成、区间4未开挖阶段,需加强此时段路基监控量测。加强超前支护、合理选择施工工法是控制路基沉降的有效手段。

Analysis of the impact of underground cross- engineering on tram subgrade

It is an important risk source on crossing the existing tram subgrade by the engineering of main metro line and shaft cross aisle. Due to its complex position relation, both the construction of main metro line and shaft cross aisle would affect the tram subgrade. The timing and extent of impact is difficult to determine. Based on the numerical analysis method, the whole process of tram subgrade construction is simulated and the influence of the construction of the cross-engineering on tram subgrade is evaluated. The results show that adopting four steps method and double rows advance small pipe grouting at the cross aisle section, and benching tunneling method and one row advance small pipe grouting at the main metro line section could effectively control the tram subgrade settlements and ensure the safety of the tram operation; the greatest influence to the tram subgrade settlements is the stage of vertically crossing by the cross aisle, which accounts for 46.6% of the total settlement; the maximum value of subgrade tilt (non-uniform settlement) occurs after line 3 excavation, before line 4 excavation and it is necessary to strengthen the monitoring measurement of subgrade. Strengthening forepoling and choosing reasonable construction method is an effective approach to control the tram subgrade settlement.