膨胀性泥岩铁路隧道变形机理与仰拱底鼓控制技术研究  

Study on the Deformation Mechanism and Control Technology of Arch Bottom Bulging of Railway Tunnel in Expansive Mud Stone

作　　者：徐志平[1] XU Zhiping(China Railway First Survey and Design Institute Group Co.,Ltd.,Xi'an 710043,China)

机构地区：[1]中铁第一勘察设计院集团有限公司,西安710043

出　　处：《铁道标准设计》2024年第5期113-121,共9页Railway Standard Design

基　　金：中国国家铁路集团有限公司科技研发计划重大课题(K2020G034-PT01);中铁第一勘察设计院集团有限公司科研开发课题(17-20)。

摘　　要：为揭示膨胀性泥岩铁路隧道仰拱底鼓变形机理并提出对应控制措施,以西(宁)至成(都)铁路膨胀性泥岩隧道为背景,采用室内试验、数值模拟、案例调研等方法开展研究。结果发现:膨胀性泥岩在浸水后物理力学参数明显降低,随着浸水时间增加,降低速率逐渐减小,其膨胀系数为4.8%;FLAC3D中的应变软化模型通过湿度应力场与温度应力场的转化能较好模拟膨胀性泥岩浸水后的参数衰减效应,当初始含水率分别为5%、15%、25%时,膨胀力试验结果分别为37.84,123.90,189.06kPa;随着水位上升,隧周孔隙水压力逐渐增大,当地下水位分别为Z=-5 m、Z=0 m、Z=5 m、Z=10 m、Z=15 m、Z=30 m时,隧周最大孔隙水压力分别为0,100,125,200,250,350 kPa,仰拱底部随软化系数的增加由沉降逐渐变为隆起,隧底围岩软化及上部挤压造成的剪切破坏是仰拱底鼓的最大诱因;随着仰拱矢跨比增加,二次衬砌弯矩减小,拱底和墙脚位置二次衬砌弯矩减小值较大,因此仰拱底部受力得到优化;适当提高仰拱矢跨比,采用全环钢架+钢筋混凝土衬砌、加强基底排水、采用基底换填或管桩加固等措施是膨胀性泥岩铁路隧道设计关键。To reveal the deformation mechanism of arch bottom bulging of railway tunnel in expansive mud stone and propose corresponding control measures,indoor experiments,numerical simulations,case studies,and other methods are employed to study expansive mud stone tunnel of Xi'ning to Chengdu Railway.The results shows that the physical and mechanical parameters of the expansive mud stone significantly decreases after immersion,and rate of decrease gradually drops with increasing immersion time,its expansion coefficient is 4.8%.The strain-softening model in FLAC3D simulates the parameter attenuation effect of expansive mud stone effectively after immersion through the conversion of humidity stress field and temperature stress field,and when initial moisture content is 5%,15%,and 25%,results of the expansion force test are 37.84 kPa,123.90 kPa and 189.06 kPa,respectively.As water level rises the pore water pressure around tunnel gradually increases,and when groundwater levels are Z=-5 m,Z=0 m,Z=5 m,Z=10 m,Z=15 m,and Z=30 m,the maximum pore water pressure around the tunnel is 0,100,125,200,250,and 350 kPa,respectively.As softening coefficient increases,arch bottom gradually changes from settlement to uplift,and the softening of rock mass at the tunnel bottom and shear failure caused by upper compression are the biggest causes of the arch bottom bulging.As the rise to span ratio of arch bottom increases,bending moment of the secondary lining decreases,and bending moment at arch bottom and arch foot decrease significantly,and the stress at the arch bottom is optimized.Improving the rise to span ratio of the arch bottom appropriately,adopting measures such as full ring steel frame+reinforced concrete lining,strengthening drainage of the foundation,and using foundation replacement or pipe pile reinforcement are the keys to the design of railway tunnels in expansive mud stone.

关 键 词：铁路隧道 膨胀性泥岩 仰拱底鼓 变形机理 变形控制技术 参数优化 

分 类 号：U25[交通运输工程—道路与铁道工程] U459.1[建筑科学—桥梁与隧道工程]