单洞双线地铁盾构施工地表沉降规律研究

Study on Ground Settlement Law of a Double-track Running Tunnel in Construction

以北京地铁14号线某单洞双线盾构施工为背景,采用FLAC3D软件建立三维数值模型,研究盾构施工参数及地层参数对地表沉降的影响.研究表明:盾构推进时,沿隧道纵向地表沉降呈现4阶段变化规律.当盾构脱出盾尾时,地表沉降速率最大;随着注浆层的硬化,地表沉降值缓慢变化,并最终趋于稳定值;地层弹性模量对地表沉降的影响较大;当开挖面支护压力达到一定值后,增大开挖面支护压力,并不能有效的控制地表沉降;注浆层的硬化时间对地表沉降有一定的影响,但考虑到实际现场施工状况,取延迟6环注浆层硬化较为合理.

Based on a double-track running tunnel of Beijing metro line 14,a three-dimensional numerical model is established by FLAC3D software to study the influence of shield construction parameters and stratum parameters on ground settlement.Research shows that there are four obvious stages of surface settlement along the longitudinal direction of the tunnel during shield tunneling.When the shield is pulled out of the shield tail,the surface settlement rate is the largest.With the hardening of the grouting layer,the surface settlement value changes slowly and finally tends to be stable.The elastic modulus of stratum has great influence on surface settlement.When the support pressure of the excavation face reaches a certain value,the surface settlement cannot be controlled effectively by increasing the support pressure on the excavation face.The hardening time of grouting layer has a certain influence on the ground settlement,considering the actual construction situation,it is more reasonable to delay the hardening of 6 ring grouting layer.