第三系半成岩富水砂岩隧道水平高压旋喷桩加固机理及参数分析  

Reinforcement mechanism and parameter analysis of horizontal high-pressure rotary jet grouting piles for tunnels in tertiary semi-diagenetic water-rich sandstone

作　　者：许劲松 徐华[2,4] 张海涛 王秋懿 李宝华 XU Jinsong;XU Hua;ZHANG Haitao;WANG Qiuyi;LI Baohua(College of Civil Engineering,Tongji University,Shanghai 200092,China;College of Environmental and Civil Engineering,Chengdu University of Technology,Chengdu 610059,China;YCIC Investment Company Limited,Kunming 650100,China;Research on complex Geological TBM Intelligent Excavation and Disaster Prevention Engineering Technology in Sichuan Province,Chengdu 610059,China)

机构地区：[1]同济大学土木工程学院,上海200092 [2]成都理工大学环境与土木工程学院,四川成都610059 [3]云南交投集团投资有限公司,云南昆明650100 [4]四川省复杂地质TBM智能掘进与灾害防控工程技术研究中心,四川成都610059

出　　处：《岩土工程学报》2024年第12期2559-2569,共11页Chinese Journal of Geotechnical Engineering

基　　金：交通运输部重点科技项目(2019-MS1-017)。

摘　　要：第三系半成岩具备弱胶结、遇水软化等特征,隧道建设时易诱发涌水突泥和坍塌等地下地质灾害。依托云南临清高速公路王家寨隧道,结合现场地质条件与现有工程案例,采用水平高压旋喷桩对软弱围岩进行超前预加固。结合地基梁理论解析、数值模拟与现场监测方法,研究第三系半成岩水平高压旋喷桩加固机理及不同桩体参数对围岩加固效果的影响,并给出桩体参数建议范围,为类似工程提供参考。研究表明:旋喷桩加固后解析解与数值解的剪力与弯矩分布规律较为一致,在开挖未支护段桩体所受弯矩、剪力最大,最易发生断裂破坏;当围岩水压力在300 kPa时旋喷桩体最大拉应力达598.21 kPa,接近桩体极限抗拉强度,水压力小于300 kPa时水平旋喷桩能有效发挥梁、拱协同作用,拱棚效应与阻水效果显著,能将围岩压力传递给桩体后端及拱肩、边墙处,围岩沉降与地下水压得到有效控制,这与现场监测结果基本吻合;桩径、桩长、咬合厚度及搭接长度变化对桩体应力影响较大,影响程度为咬合厚度>桩长>搭接长度>桩径,建议在第三系半成岩富水砂岩隧道围岩水压力小于300 kPa进行超前预加固时,水平旋喷桩桩体参数范围为桩径65~70 cm、桩长10~13 m、咬合厚度25 cm、搭接长度3~4 m。The tertiary semi-diagenetic rocks are characterized by weak cementation and susceptibility to water softening,which can easily trigger underground geological disasters such as water inrushes,mud outbursts and collapses during tunnel construction.Focusing on the Wangjiazhai tunnel of the Lincan-Qingshuihe Expressway in Yunnan Province,considering the geological conditions and the relevant engineering case studies,the horizontal high-pressure rotary jet grouting piles are employed to pre-emptively strengthen the weak surrounding rock.Through the combination of theoretical analysis of foundation beams,numerical simulation and field monitoring methods,the reinforcement mechanism of horizontal high-pressure jet grouting piles in the tertiary semi-diagenetic formations is investigated,and the influences of varying pile parameters on the reinforcement effectiveness of the surrounding rock are examined,offering a suggested range for these parameters to serve as a reference for similar projects.The results indicate that the distribution of shear force and bending moment in both analytical and numerical solutions agrees with that in the unsupported section,where the pile experiences the highest bending moments and shear forces,making it most susceptible to fracture failure.Under the water pressure of the surrounding rock of 300 kPa,the maximum tensile force within the rotary jet grounting pile reaches 598.21 kPa,close to the ultimate tensile strength of the pile.When the water pressure is below 300 kPa,the horizontal rotary jet pile can effectively give full play of the combined effects of beam and arch,significantly enhancing both the arch action and the water-blocking effects.This allows the pressures on the surrounding rock to be redistributed to the pile rear,the spandrel and the sidewall.The settlement of the surrounding rock and the underground water pressure are effectively controlled,which are consistent with the field monitoring results.The pile diameter,length,occlusion thickness and overlap length significantly

关 键 词：第三系半成岩 水平高压旋喷桩 加固机理 现场监测 桩体参数分析 

分 类 号：TU43[建筑科学—岩土工程]