中老铁路隧道软弱围岩大变形特征试验研究  

Experimental Research on Large Deformation Characteristics of Weak Surrounding Rock Tunnel of China-Laos Railway

作　　者：谭忠盛[1] 李松涛 王建军 杨旸[1] TAN Zhongsheng;LI Songtao;WANG Jianjun;YANG Yang(Key Laboratory of Urban Underground Engineering,Ministry of Education,Beijing Jiaotong University,Beijing 100044,China;Sinohydro Bureau 3 Co.,Ltd.,Xi’an Shaanxi 710000,China)

机构地区：[1]北京交通大学城市地下工程教育部重点实验室,北京100044 [2]中国水利水电第三工程局有限公司,陕西西安710000

出　　处：《中国铁道科学》2021年第4期98-106,共9页China Railway Science

基　　金：国家自然科学基金资助项目(51978041)。

摘　　要：针对中老铁路穿越琅勃拉邦缝合带引发的隧道大变形问题,采用室内外试验、数值模拟等方法,研究缝合带内5座隧道的围岩强度、地应力场分布规律、围岩松动圈范围以及隧道宏观变形破坏特征,提出相应的变形控制措施。试验结果表明:隧道群岩石平均单轴抗压强度约12.7 MPa,采用广义Hoek-Brown屈服准则换算得到岩体平均抗压强度约1.67 MPa;空心包体应力解除法测得隧道群最大主应力均为水平方向,且与隧线方向大角度相交,最大与最小主应力之比均大于1.5;声波法测得围岩松动圈范围为5.5~7.0 m,超过隧道洞跨的0.65倍;围岩变形最大水平收敛达600 mm以上,相比同类隧道,隧道群的变形量更大、变形速率更高且水平挤压收敛变形更为突出。数值模拟进一步揭示,隧道群围岩变形具有显著的非线性和非对称性特征,会进一步加剧隧道围岩大变形的发生。为此,提出隧道变形控制措施以调整隧道断面结构形式、改变施工工法及台阶长度、优化锚杆间距和方位以及加强拱架和锁脚强度为主。Aiming at the large deformation problem of tunnels caused by China-Laos Railway crossing the Luang Prabang suture zone,indoor and outdoor tests and numerical simulation were carried out to study the strength of surrounding rock,the distribution of geo-stress field,the loose zone of surrounding rock and the macroscopic deformation and failure characteristics of 5 tunnels within the suture zone,and the corresponding deformation control measures were put forward.The tests results show that the average uniaxial compressive strength of the tunnel group rock is about 12.7 MPa,and the average compressive strength of the rock mass converted from the generalized Hoek-Brown yield criterion is about 1.67 MPa.By applying the hollowinclusion stress relief method,the maximum principal stress of the tunnel group is in the horizontal direction,which intersects with the tunnel line direction at a large angle.The ratio of the maximum principal stress to the minimum principal stress is larger than 1.5.The loose zone of surrounding rock measured by acoustic emission method is about 5.5-7.0 m,which is more than 0.65 times of tunnel span.The maximum horizontal convergence of surrounding rock deformation is more than 600 mm.Compared with similar tunnels,the deformation of this tunnel group is larger,the deformation rate is higher and the convergence deformation of horizontal extrusion is more prominent.The numerical simulation further reveals that the deformation of surrounding rock of tunnel group has significant nonlinear and asymmetric characteristics,which will further aggravate the large deformation occurrence of tunnel surrounding rock.Therefore,the control measures for tunnel deformation are put forward to adjust the structural form of tunnel section,change the construction method and the bench length,optimize the spacing and orientation of rock bolts and improve the strength of arch centering and locked springing.

关 键 词：中老铁路 软弱围岩隧道 试验研究 围岩变形 围岩单轴抗压强度 地应力 围岩松动圈 

分 类 号：U452.1[建筑科学—桥梁与隧道工程]