浅埋软弱围岩隧道基于变形稳定性的施工方案研究

Deformation and Stability Based Study of the Construction Scheme for Shallow-Buried Tunnels in Weak Surrounding Rock

浅埋暗挖隧道施工不可避免地对地层产生扰动,引起地层变形;尤其是在建筑区地面荷载全部作用于建筑物基础时,对隧道结构变形和地表建筑物的沉降会形成很大的威胁。因此,优化施工方案对控制隧道围岩过度变形、有效减少地表建筑物沉降意义重大。文章以兰渝铁路人和场隧道下穿地表建筑物为工程背景,对台阶法、CD法及CRD法三种施工方案进行了数值模拟,对比分析了隧道围岩位移场、塑性区的分布特征,以及开挖对掌子面附近围岩的扰动效应、围岩变形的时空效应及基础沉降的影响,并提出了安全、经济的最佳施工方案。研究结果表明,人和场隧道采用台阶法施工是非常可行的。

The construction of a shallow-buried tunnel inevitably disturbs the stratum and causes ground settle- ment, especially in the building zone, where all ground loads act on building foundations, readily causing tunnel structure deformation and building settlement. Therefore the optimization of construction schemes is vital for con- trolling excessive deformations of the surrounding rock and reducing the settlements of surface buildings. Based on the construction of the Renhechang tunnel on the Lanzhou-Chongqing railway underneath surface buildings, a numerical simulation was carried out regarding the bench cut method, CD method, and CRD method, and a con- trastive analysis of the displacement field of surrounding rock and the distribution characteristics of the plastic zone was conducted. Additionally a study of the disturbance effect of excavation on surrounding rocks near the working face was performed, and the space-time effect of surrounding rock deformation and the influence on foundation settlement were analyzed. The soundest and most economic construction scheme is presented. The re- sults show that bench cut method is feasible for the Renhechang tunnel construction.