摘要
目前针对小曲率盾构开挖诱发地层沉降的理论研究一般将地基视为线弹性体,未考虑土体流变特性的影响,因此无法准确预测时间效应下盾构沿曲线路径开挖的沉降变化。首先,建立Boltzmann黏弹性地基中的小曲率隧道掘进力学模型,将线弹性地层参数泊松比、剪切模量进行Laplace变换,得到了黏弹性地层的时域参数;其次,将地层损失解及Mindlin位移解进行Laplace正逆变换,推导出黏弹性地层小曲率盾构施工中,因超挖地层损失、盾构尾部地层损失、刀盘面不平衡推力、盾壳不平衡摩擦力及盾尾注浆压力共同影响的沉降解;最后,将工程实测数据及三维数值模拟结果与解析解进行对比验证,得到了较好的一致性。此外,针对隧道曲率半径、盾构刀盘面半径及黏弹性地层剪切模量比等进行参数分析。分析结果表明:小曲率隧道内外侧横向地表沉降呈不对称分布,沉降峰值向内侧偏移,随时间增长,沉降槽曲线向下移动,沉降量增大;相较于较大的隧道曲率半径,较小的曲率半径发生等量变化时对地层沉降的影响更显著;隧道曲率半径及黏弹性地层剪切模量比的减小,刀盘面半径及超挖量的增大,使得盾构尾部处横向地表沉降增大,也使得刀盘面前方和后方地表的隆起与沉降均增大。
Current theoretical studies on ground settlement induced by small curvature shield excavation generally consider the foundation as linear elastic bodies,neglecting the rheological behavior of soil.Therefore,the time-dependent settlement changes of shield excavation along curved path cannot be accurately predicted.A mechanical model for small curvature tunneling in a Boltzmann viscoelastic foundation was established.Time domain parameters of the viscoelastic ground were obtained through Laplace transforms of the Poisson’s ratio and shear modulus for the linear elastic ground parameters.Then,the solutions for ground loss and Mindlin displacement were converted by positive and inverse Laplace transforms.During small curvature shield construction in the viscoelastic ground,a settlement solution was derived that accounts for the combined effects of over-excavated ground loss,shield tail ground loss,cutterhead face thrust imbalance,shield shell friction imbalance and slurry pressure at the shield tail.Finally,field measurements and three-dimensional numerical simulation results are compared with the analytical solution to verify its relative accuracy.In addition,the parameters of tunnel curvature radius,shield cutterhead face radius and viscoelastic ground shear modulus ratio are analyzed.The analysis results show that the transverse surface settlement inside and outside the small curvature tunnel is asymmetrically distributed,with the peak settlement shifting inward.The settlement trough curve shifts downward and the settlement volume increases with time.A smaller tunnel curvature radius has a more significant effect on ground settlement compared to a larger tunnel radius curvature with equal changes.Reduction in tunnel curvature radius and viscoelastic ground shear modulus ratio,along with growth in cutterhead face radius and over-excavated value,result in the increase in transverse surface settlement at the shield tail,as well as the increase in uplift and settlement of the longitudinal surface both before and behind the cutterhead face.
作者
张治国
陈胤吉
朱正国
魏纲
孙苗苗
ZHANG Zhi-guo;CHEN Yin-ji;ZHU Zheng-guo;WEI Gang;SUN Miao-miao(School of Environment and Architecture,University of Shanghai for Science and Technology,Shanghai 200093,China;State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,Shijiazhuang Tiedao University,Shijiazhuang,Hebei 050043,China;Department of Civil Engineering,Hangzhou City University,Hangzhou,Zhejiang 310015,China;Zhejiang Engineering Research Center of Intelligent Urban Infrastructure,Hangzhou City University,Hangzhou,Zhejiang 310015,China)
出处
《岩土力学》
北大核心
2025年第S1期309-321,共13页
Rock and Soil Mechanics
基金
国家自然科学基金(No.52478402,No.42177145)
省部共建交通工程结构力学行为与系统安全国家重点实验室课题(No.KF2022-07)
城市基础设施智能化浙江省工程研究中心课题(No.IUI2022-YB-01)
关键词
黏弹性地层
小曲率隧道
超挖量
地层沉降
LAPLACE变换
viscoelastic ground
small curvature tunnel
over-excavated value
ground settlement
Laplace transform
