非贯穿式浅埋矩形隧道导洞开挖顺序优化

Optimization of Excavation Sequence for Pilot Tunnels of a Non-penetrating Shallow Rectangular Tunnel

矩形隧道虽具有空间利用率较高的优点,但其承载性能较拱形隧道差。文章基于某新建CRD法非贯穿式地铁附属浅埋矩形隧道,对其导洞开挖顺序进行数值模拟分析。通过对比分析隧道围岩竖向位移和初期支护结构受力情况以及隧道上方的横向、纵向地表沉降等指标,揭示了该隧道初期支护结构及围岩的变形特点;继而选出较合理的开挖顺序进行施工,并通过施工监测数据检验了分析的合理性。研究表明:(1)隧道围岩的变形与导洞开挖顺序有密切的关系;(2)非贯穿式隧道开挖引起的地表沉降量随着隧道开挖深度增加而逐渐减小;(3)对于4导洞CRD法矩形隧道,采用左右非对称的导洞开挖顺序可有效控制围岩变形。

Rectangular tunnel has the advantage of high space utilization,but it is relatively rare because of its poor bearing capacity compared with arch tunnel,and the related research is also less.In this paper,based on a newly built non-penetrating shallow rectangular tunnel of subway subsidiary structure with CRD method,the different excavation sequences of pilot tunnels are numerical simulated and analyzed.By comparing and analyzing the vertical displacement of surrounding rock,the stress condition of primary support and the surface settlement of the tunnel,the deformation law of the supporting structure and surrounding rock of the tunnel is revealed.Then,a more reasonable excavation sequence is selected for construction,and its rationality is tested through the construction process.The results show that:(1)the deformation of tunnel surrounding rock is closely related to the excavation sequence of pilot tunnel;(2)the surface settlement caused by non-penetrating tunnel excavation decreases gradually with the increase of tunnel excavation depth;(3)for the rectangular tunnel with 4 pilot tunnels and excavated by CRD method,the unsymmetrical pilot tunnel excavation sequence can effectively control the deformation of surrounding rock.