大断面软弱围岩隧道洞口段施工工法比较分析  

Comparison of Construction Methods for Portals of Some Shallow Weak-Rock Tunnel

作　　者：邓祥辉[1,2] 

机构地区：[1]西安工业大学建筑工程学院,西安710021 [2]长安大学公路学院,西安710064

出　　处：《西安工业大学学报》2013年第12期974-981,共8页Journal of Xi’an Technological University

基　　金：国家自然基金委研究基金项目(51278063);交通部西部项目(2013318J12330);陕西省教育厅自然基金项目(2010JK599)

摘　　要：山岭隧道建设条件复杂,通常洞口段埋深较浅、围岩破碎,在施工过程中易发生坍塌、边仰坡失稳等事故.根据某隧道洞口段地质情况、地形条件以及设计参数,对拟采用的交叉中隔壁法和双侧壁导坑法进行施工和数值分析对比.研究结果表明:从施工上看,采用交叉中隔壁法有利于工期;从数值分析看,采用交叉中隔壁法和双侧壁导坑法完成开挖后,隧道结构Y向最大沉降分别为6.65cm和1.68cm,临时支撑X向最大变形分别为20.5cm和4.42cm,采用后者施工变形更小;从计算结果看,采用双侧壁导坑法施工,围岩和隧道支护结构受力更小.采用交叉中隔壁法施工后,C25喷射混凝土Y向最大拉应力为3.07MPa,远大于采用双侧壁导坑法的1.27MPa,且超过该喷射混凝土的极限抗拉强度.因此,从隧道变形和受力分析看,采用双侧壁导坑法施工更安全.Construction conditions of mountain tunnel are very complex. Generally, it is liable to the security risk event, for example collapse and face-upward slope failure. In the construction of tunnel portal in the conditions of shallow buried depth and broken surrounding rock. CRD method and double sides heading method are applied and compared in the portals of some tunnel according to geological condition, terrain condition and design parameters. The results show： It is beneficial to shorten construction period with CRD method according to comparing construction procedures. The maximum vertical displacements of tunnel structure are 6. 65 cm and 1. 68 respectively when CRD method and double sides heading method are used;Maximum horizontal convergenees of the temporary supports are 6.65 cm and 1.68 respectively. It is obvious that the deformations are smaller when double sides heading method is used. Meanwhile,it has been already proved by the calculation results that surrounding rock and supporting structures bear the smaller stresses. Especially, maximum tensile stress reachs 3. 07 MPa with CRD method and is more than ultimate tensile strength of C25 shotcrete while maximum tensile stress of C25 shotcrete is 1.27 MPa with double sides heading method. Therefore, it is safer with double sides heading method in this tunnel according to deformation and stress analysis.

关 键 词：大断面软弱围岩隧道 洞口段 施工工法 交叉中隔壁法 双侧壁导坑法 

分 类 号：U455.4[建筑科学—桥梁与隧道工程]