浅埋大断面矩形顶管掘进面稳定性及支护压力分析

Analysis of stability and support pressure of driving face in shallow buried rectangular pipe jacking with large section

以苏州市轨道交通5号线某车站附属地下工程为背景,对矩形顶管掘进面稳定性问题进行研究.建立梯形楔形体修正模型,基于极限平衡理论,推导出有效支护压力表达式.通过最优化方法得到破坏模式及其对应的极限支护压力,并进行参数分析.结果表明:支护压力随土体强度参数增大而减小,随隧道几何参数增大而增大;与传统筒仓模型相比较,发现优化模型计算得出的极限支护压力值更大,且更有利于规避施工风险;工程实际支护压力(71.00~90.00 kPa)大于模型计算结果(51.36 kPa),说明仓内支护压力合适,由此推测,依托工程发生的地表塌陷或较大沉降是施工故障或不利地层条件引起的支护力不足造成的.

Based on the underground project attached to the station of Suzhou Rail Transit Line 5,the stability of driving face of the rectangular pipe jacking was investigated.The silo and wedge model was modified,and the effective support pressure was derived based on the limit equilibrium theory.The maximum support pressure was obtained by optimization method,and the parameter analysis was carried out.The results show that the support pressure is decreased with the increasing of soil strength parameter,and it is increased with the increasing of tunnel geometry parameter.The support pressure result obtained by the optimized wedge model is greater than that by the traditional silo model,which is conducive to avoiding construction risks.The actual support pressure(71.00-90.00 kPa)is greater than the theoretical calculation result of 51.36 kPa,which indicates that the support pressure is suitable.The surface collapse or large settlement is presumed to be construction failure or insufficient support force due to unfavorable stratum conditions.