岩土力学2024，Vol.45Issue(8)：2462-2473,12.DOI:10.16285/j.rsm.2023.1361
第三系半成岩富水砂岩隧道水平高压旋喷桩复合结构超前预加固研究
Pre-strengthening of composite structure of horizontal high-pressure jet grouting pile in tertiary semi-diagenetic water-rich sandstone tunnel
摘要
Abstract
In tunnel construction through weak and homogeneous geological layers rich in water,such as the tertiary semi-diagenetic strata,horizontal high-pressure jet grouting piles are often used for advanced reinforcement within the tunnel.However,these horizontal jet grouting piles tend to fracture under significant loads due to their low tensile strength.Drawing on the Wangjiazhai Tunnel project of the Lincang to Qingshuihe Expressway in Yunnan,a new composite structure is put forward that involves inserting small-diameter steel pipes into the pile body.Through mechanical theoretical analysis,numerical simulations,and on-site monitoring,we conducted a comparative analysis of the mechanical mechanisms and reinforcement effects of raw jet grouting piles and composite structures on the surrounding rock.Furthermore,we optimized the layout and diameter of the steel pipes.The research indicates that under a water pressure of 300 kPa,the deflection of the composite structures decreases by 34.8％,and the maximum tensile stress decreases by 37.5％compared to the untreated piles,significantly improving the stress mode and enhancing the ultimate bearing capacity of the water pressure load to 700 kPa,while also reducing the settlement of the arch crown and stress on the surrounding rocks.Increasing the density of steel pipes arranged at the arch crown effectively reduces the tensile stress in the pile body,whereas reducing the diameter of steel pipes would lead to increased tensile stress in the pipes.For practical engineering applications,it is advisable to place 108 mm steel pipes at intervals of one pile at the arch crown,place 89 mm steel pipes at intervals of two to three piles at the arch shoulders,and steel pipes are not necessary for the sidewalls.关键词
第三系半成岩/水平高压旋喷桩/钢管复合结构/受力机制/极限水压荷载Key words
tertiary semi-diagenetic rock/horizontal high-pressure jet grouting pile/steel tube composite structure/force mechanism/ultimate water pressure load分类
土木建筑引用本文复制引用
王秋懿,张海涛,张金江,徐华,王清华,许劲松..第三系半成岩富水砂岩隧道水平高压旋喷桩复合结构超前预加固研究[J].岩土力学,2024,45(8):2462-2473,12.基金项目
交通运输部重点科技项目(No.2019-MS1-017) （No.2019-MS1-017）
隧道软弱围岩洞内水平高压旋喷桩法加固技术及效果评估(No.R110121H044).This work was supported by the Innovative Key Program of Ministry of Transport of China(2019-MS1-017)and the Reinforcement Technique and Effect Evaluation of Horizontal High Pressure Jet Grouting Pile Method in Weak Rock Tunnel(R110121H044). （No.R110121H044）
