摘要
在诸如第三系半成岩地层等富水软弱均质地层的隧道建设中,常采用水平高压旋喷桩进行洞内超前预加固,但水平旋喷桩往往因自身抗拉强度低在承受较大荷载时容易发生断裂破坏。依托云南临沧至清水河高速公路王家寨隧道工程,提出了一种在桩体内插入小直径钢管的水平高压旋喷复合结构。通过力学理论分析、数值模拟与现场监测,对比分析了水平高压旋喷桩素桩与复合结构的力学机制与对围岩加固作用,并对钢管布置形式及直径进行优化设计。研究表明:在300 kPa水压下,复合结构相比素桩的挠度值降低了34.8%,最大拉应力降低了37.5%,受力模式明显改善,承受的极限水压力荷载大幅提升至700 kPa,对围岩拱顶沉降、应力也有一定削减作用;增加拱顶钢管布置密度可有效降低桩体拉应力,而减少钢管直径则会导致钢管拉应力增大;建议实际工程中拱顶间隔1根桩体布置108 mm钢管,拱肩间隔2~3根布置89 mm钢管,边墙可不设钢管。
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.
作者
王秋懿
张海涛
张金江
徐华
王清华
许劲松
WANG Qiu-yi;ZHANG Hai-tao;ZHANG Jin-jiang;XU Hua;WANG Qing-hua;XU Jin-song(Yunnan Communications Investment&Construction Group Co.,Ltd.,Investment Company Limited,Kunming,Yunnan 650100,China;College of Environmental and Civil Engineering,Chengdu University of Technology,Chengdu,Sichuan 610059,China;Sichuan Engineering Technology Research Center of Complex Geology TBM Intelligent Excavation and Disaster Prevention,Chengdu,Sichuan 610059,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu,Sichuan 610031,China;College of Civil Engineering,Tongji University,Shanghai 200092,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2024年第8期2462-2473,共12页
Rock and Soil Mechanics
基金
交通运输部重点科技项目(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)。
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
tertiary semi-diagenetic rock
horizontal high-pressure jet grouting pile
steel tube composite structure
force mechanism
ultimate water pressure load
