大断面三孔小净距隧道围岩稳定性数值研究及工程实践  

Numerical study and engineering practice for surrounding rock stability of large cross-sectional triple tunnels

作　　者：李然 陈平[1] 张顶立 王圣涛[1] 申志军 潘红桂 Li Ran;Chen Ping;Zhang Dingli;Wang Shengtao;Shen Zhijun;Pan Honggui(China Tiesiju Civil Engineering Group Co.,Ltd.,Hefei 230023,China;Key Laboratory for Urban Underground Engineering of Ministry of Education,Beijing Jiaotong University,Beijing 100044,China)

机构地区：[1]中铁四局集团有限公司,安徽合肥230023 [2]北京交通大学城市地下工程教育部重点实验室,北京100044

出　　处：《土木工程学报》2022年第11期83-95,共13页China Civil Engineering Journal

基　　金：国家重点基础研究发展计划(2017YFC0805401);国家自然科学基金(51738002);高铁联合基金重点项目(U1934210)。

摘　　要：隧道支护设计的核心目标是提高围岩自稳能力,然而大断面三孔小净距隧道围岩失稳机制尚不明确,相关控制手段也鲜有研究。依托京张高铁长城站大断面三孔小净距隧道工程,系统研究其围岩稳定特性,提出相应的控制方法,并开展工程应用。研究表明:通过一系列三维数值分析,大断面三孔小净距隧道围岩稳定特征可以凝练为超前变形破坏大与夹岩变差易失稳;后行中洞由于受先行边洞开挖扰动的剧烈影响,造成过大超前变形和严重超前破坏,因此中洞安全状态最差;为防止围岩失稳破坏,提出纵向超前控制和横向夹岩控制两种方法,通过数值分析对超前支护参数进行优化,并研究管棚与帷幕注浆联合超前控制效果;控制措施在长城站得到工程实践,控制手段应用后,拱顶沉降减少62.5%,横向收敛缩小48.0%,围岩压力降低25.2%,有效保证隧道开挖安全。The core aim of tunnel support design is to improve the self-stability of surrounding rock.However,the rock instability mechanism of large cross-sectional closely-spaced triple tunnels is still unclear,and the control methods have been rarely studied.Relying on the large cross-sectional triple tunnels project of Great Wall Station of Beijing Zhangjiakou high-speed railway,the rock instability mechanism was systematically studied,the control methods were correspondingly put forward and subsequently applied to engineering practice.It was found that:through a series of three-dimensional numerical analyses,the rock instability of large cross-sectional triple tunnels shall be characterized by large pre-deformation,serious pre-failure,and unstable rock pillar.The lagging middle tunnel was severely disturbed by the leading side tunnel excavations,resulting in excessive pre-deformation and serious pre-damage.Hence,the middle tunnel was in the worst safety state.Two methods,namely the longitudinal pre-control and the lateral pillar protection,were proposed to prevent the entire failure of triple tunnels.The pre-support parameters were optimized through numerical analysis,and the combined control effect of pipe roof and curtain grouting was studied.These control measures were practically applied to the large cross-sectional triple tunnels of the Great Wall Station.After the application of the control measures,the crown settlement was reduced by 62.5%,the horizontal convergence was decreased by 48.0%,and the rock pressure was reduced by 25.2%,which effectively ensured the excavation safety of the tunnel project.

关 键 词：三孔小净距隧道 大断面隧道 围岩稳定性 超前支护 中夹岩 数值模拟 现场实测 

分 类 号：U458􀆰[建筑科学—桥梁与隧道工程]