某引水隧洞大变形缓冲层支护方案设计参数优化研究  

Optimization of design parameters for support scheme of a high compression cushioning layer in a diversion tunnel

作　　者：舒晓云 田洪铭[1] 陈卫忠[1] 朱珍德 杨帆 田云 张朝轩 张韬 SHU Xiao-yun;TIAN Hong-ming;CHEN Wei-zhong;ZHU Zhen-de;YANG Fan;TIAN Yun;ZHANG Chao-xuan;ZHANG Tao(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;College of Civil and Transportation Engineering,Hohai University,Nanjing,Jiangsu 210024,China;Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province,Shaoxing University,Shaoxing,Zhejiang 312000,China;Zhongshui North Survey,Design and Research Co.,Ltd.,Tianjin 300222,China)

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [2]河海大学土木与交通学院,江苏南京210024 [3]绍兴文理学院岩石力学与地质灾害浙江省重点实验室,浙江绍兴312000 [4]中水北方勘测设计研究有限责任公司,天津300222

出　　处：《岩土力学》2024年第10期3117-3129,共13页Rock and Soil Mechanics

基　　金：国家自然科学基金重大项目(No.42293355);国家自然科学基金(No.52179113,No.52279119,No.U2340229,No.42207199);博士后科研项目(No.ZJ2022155,No.GZC20240167);湖州市重点实验室基金(No.HGB23E002);武汉市知识创新专项基础研究项目(No.20220108010163)。

摘　　要：高地应力软岩隧道围岩变形具有显著的时效特性,容易引起运营期隧道衬砌结构开裂和破坏。以新疆某引水隧洞泥岩大变形段为背景,提出在初期支护与二次衬砌之间设置高压缩缓冲层的支护方案,以保证隧洞在运营期安全。首先针对现有缓冲层支护方案,开展了支护结构受力的现场监测与分析,然后采用数值仿真方法对缓冲层支护方案进行了参数优化,最后将优化后方案与原方案的支护效果进行了对比分析。(1)现有支护方案的监测结果表明:当现场安装密度为90~100 kg/m~3的5 cm聚乙烯缓冲层后,缓冲层易进入压密阶段,围岩形变压力达到0.36 MPa,衬砌受力仍具有非均匀性,缓冲层材料和厚度还有可优化的空间。(2)缓冲层支护参数优化表明:缓冲层平台应力偏大会导致其难以被压缩而降低吸能效果,偏小将难以有效限制围岩变形,两者都会造成缓冲层对围岩形变能的吸收不足,衬砌的安全性较低。随着缓冲层厚度的增加,衬砌破坏程度逐渐减小,但减小幅度逐渐减弱。对于本工程而言,当平台应力为0.5 MPa,压缩率≥0.6,厚度为10 cm时,缓冲层支护效果最佳。(3)对比分析表明:相比于原缓冲层支护方案,优化后的缓冲层支护将使得衬砌最大主应力减小了20%~30%,缓解衬砌的应力集中程度,可保障隧道支护结构的长期稳定。Soft rock tunnel surrounding rock deformation exhibits significant time-dependent characteristics,potentially causing cracking and damage of tunnel linings during operation.This study focuses on a highly deformable mudstone section in a water diversion tunnel in Xinjiang,and proposes a support scheme with a high compression cushioning layer between initial support and secondary lining to ensure the long-term safety of the tunnel.The existing cushioning layer support scheme was initially subjected to on-site monitoring and structural forces analysis.Subsequently,numerical simulation methods were used to optimize the cushioning layer support parameters.Finally,the optimized and original schemes were compared to analyse their respective support effects.(1)Monitoring of the existing support scheme reveals that,with the installation of a 5 cm polyethylene cushioning layer at a density of 90–100 kg/m3,the surrounding rock pressure reaches 0.36 MPa,indicating the compression phase of the cushioning layer.The non-uniformity of lining force is evident,suggesting potential for optimizing the cushioning layer material and thickness.(2)Optimization of cushioning layer support parameters indicates that if the stress of buffer layer platform is too high,it cannot fully absorb energy,and if too low,it cannot effectively limit surrounding rock deformation.Both scenarios result in insufficient energy absorption and low lining safety.Increasing the cushioning layer thickness gradually reduces lining damage degree,but the reduction rate diminishes over time.For this project,the optimal cushioning layer support is achieved with a platform stress of 0.5 MPa,a compression ratio of≥0.6,and a thickness of 10 cm.(3)Comparative analysis indicates that the optimized cushioning layer support reduces the maximum principal stress on the secondary lining by 20%–30%compared to the original scheme,alleviating stress concentration in the lining and ensuring the long-term stability of the tunnel support structure.

关 键 词：时效变形 隧道支护 缓冲层 数值模拟 参数优化 

分 类 号：TE93[石油与天然气工程—石油机械设备]