强风化炭质片岩隧洞大变形特征及合理开挖方案  

Characteristics of Large Deformation in Strongly Weathered Carbonaceous Schist Tunnel and Reasonable Excavation Scheme

作　　者：张明杰 吴永红[1] ZHANG Mingjie;WU Yonghong(Faculty of Civil Engineering and Mechanics,Kunming University of Science and Technology,Kunming 650500,Yunnan,China)

机构地区：[1]昆明理工大学建筑工程学院,云南昆明650500

出　　处：《水力发电》2024年第12期51-58,77,共9页Water Power

基　　金：国家自然科学基金资助项目(52369023)。

摘　　要：云南某高速公路隧道浅埋偏压段为强风化炭质片岩洞段,实际开挖过程中出现大变形,通过现场监控量测,得到该洞段大变形的规律及特点。采用有限差分软件FLAC 3D,左洞和右洞分别拟定三台阶法和三台阶法、三台阶法和三台阶七步法、三台阶法和双侧壁导坑法、三台阶七步法和三台阶七步法以及双侧壁导坑法和三台阶七步法等5种开挖组合方案,建立计算模型,对5种不同开挖方案下左右洞的变形特征进行计算分析。结果表明:右洞围岩竖向沉降持续时间较长,拱顶处变形量较大;左洞围岩水平收敛持续时间较长,向内挤出变形量较大;采用双侧壁导坑法和三台阶七步法的方案五开挖,左洞拱顶沉降、拱肩收敛及拱腰收敛分别减少了16.8%、36.6%、31.9%,右洞拱顶沉降、拱肩收敛及拱腰收敛分别减少了26.4%、15.1%、9.4%,说明该开挖方法可有效减小隧洞浅埋偏压段的大变形。The shallow-buried biased section of a highway tunnel in Yunnan Province is excavated in strongly weathered carbonaceous schist,and large deformation occurs during actual excavation.The regularity and characteristics of the large deformation of tunnel section are obtained through field monitoring and measurement.In order to obtain the reasonable excavation scheme,five excavation combination schemes for the excavation of left and right holes,including three-bench method and three-bench method,three-bench method and three-bench seven-step method,three-bench method and double sidewall heading method,three-bench seven-step method and three-bench seven-step method,and double sidewall heading method and three-bench seven-step method,are drawn up respectively,and the finite difference software FLAC 3D is used to calculated the deformation characteristics of left and right holes under the five excavation combination schemes.The results show that,(a)the vertical settlement of the surrounding rock of the right hole lasts a longer time,and the deformation at the arch top is larger;(b)the horizontal convergence duration of the surrounding rock in the left hole is longer,and the deformation of the inward extrusion is larger;and(c)when the excavation combination scheme V is used to excavate the left and right holes respectively,the settlement of arch top,the convergence of arch shoulder and the convergence of arch waist of the left hole are reduced by 16.8%,36.6%and 31.9%,respectively,and that of the right hole are reduced by 26.4%,15.4%and 15.9%,respectively,indicating that the excavation scheme can effectively reduce the large deformation of the shallow-buried biased section of the tunnel.

关 键 词：隧道开挖 强风化炭质片岩 大变形 双侧壁导坑法 三台阶七步法 有限元分析 

分 类 号：U455.4[建筑科学—桥梁与隧道工程]