摘要
为保障浅埋盾构隧道施工时盾构始发的安全性和稳定性,提出1种改进的对数螺旋线加直线的组合式滑动模式,并建立改进的端头土体极限平衡模型(M-SLEM),推导盾构始发时端头土体纵向合理加固长度的计算式;依托广州地铁18号线沙溪站盾构始发工程,计算M-SLEM和既有端头土体极限平衡模型(SLEM)下不同安全系数对应的端头土体纵向加固长度,对比隧道埋深、隧道直径、加固土体黏聚力和原状土体内摩擦角4种因素的影响及各自敏感性;采用数值模拟方法,验证2种模型下的土体滑移破坏模式和土体加固效果。结果表明:M-SLEM下,随着安全系数增大,端头土体纵向合理加固长度呈非线性增加趋势;端头土体纵向合理加固长度会随隧道埋深和隧道直径呈线性增加,随加固土体黏聚力和土体内摩擦角呈线性减小,且隧道埋深和加固土体黏聚力的影响相对较大;M-SLEM下的滑移线与数值模拟的吻合度较高,而SLEM明显低估了土体滑移范围;兼顾安全与经济,依托工程端头土体纵向加固长度取12.8 m时可获得良好的加固效果。
In order to ensure the safety and stability at the shield launching in the construction of shallow shield tunnel,an improved combined sliding mode of logarithmic spiral and straight line was proposed,and an improved limit equilibrium model(M-SLEM)for end soil was established to derive the calculation formula of longitudinal reasonable reinforcement length for the end soil at the shield launching.Relying on the shield launching project of Shaxi Station of Guangzhou Metro Line 18,M-SLEM and the existing end soil limit equilibrium model(SLEM)were used to calculate the longitudinal reinforcement lengths of end soil corresponding to different safety factors.The influence and individual sensitivity of the four factors including the tunnel depth,tunnel diameter,the cohesion of the reinforced soil and the internal friction angle of the undisturbed soil were analyzed.The failure modes of soil slip and the effects of soil reinforcement under the two models were verified by numerical simulation.The results show that according to M-SLEM,the longitudinal reasonable reinforcement length of end soil increases in a nonlinear trend as the safety factor increases.The longitudinal reasonable reinforcement length of end soil linearly increases with the depth and diameter of the tunnel,and linearly decreases with the cohesion of the reinforced soil and the internal friction angle of the soil.The influences of the tunnel depth and the cohesion of the reinforced soil are relatively large.The slip lines calculated by M-SLEM are closely coincided with those by numerical simulation,while SLEM apparently underestimates the slip range of the soil.Considering both safety and economy,a good reinforcement effect can be obtained when the longitudinal reinforcement length of end soil for the project is 12.8 m.
作者
晏启祥
陆志明
彭旸
孙明辉
王新强
雷元亮
YAN Qixiang;LU Zhiming;PENG Yang;SUN Minghui;WANG Xinqiang;LEI Yuanliang(Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu Sichuan 610031,China;The 2nd Engineering Co.,Ltd.,China Railway Construction Bridge Engineering Bureau Group Co.,Ltd.,Tianjin 300300,China)
出处
《中国铁道科学》
EI
CAS
CSCD
北大核心
2022年第6期65-75,共11页
China Railway Science
基金
国家自然科学基金资助项目(51678500,U1734205)
四川省科技计划资助项目(2019YFG0001)。
关键词
隧道
浅埋盾构隧道
盾构始发
端头土体
加固长度
极限平衡
Tunnel
Shallow shield tunnel
Shield launching
End soil
Reinforcement length
Limit equilibrium
