摘要
基坑卸荷将对下卧既有隧道产生附加荷载。结合工程实际,提出考虑隧道剪切效应及埋深效应的基坑开挖下卧隧道形变响应的半解析解。引入能考虑隧道埋深的修正基床反力系数,再由Mindlin解给出基坑卸荷对下卧隧道产生的附加荷载。视既有隧道为埋置于Pasternak地基上的Timoshenko梁,将附加荷载施加于隧道并计算其响应,提出可考虑隧道埋深及剪切效应的下卧隧道在基坑卸荷下的响应解。与三维有限元数值模拟、杭州地铁一号线九寨河基坑的测量结果的对比,验证了所提方法的准确性。针对隧道等效抗弯刚度、等效剪切刚度对隧道内力及变形的影响进行系统的敏感性分析。结果表明,采用Timoshenko梁模拟隧道可更好地分析隧道的力学响应;当提高隧道抗弯刚度,隧道的位移值、弯矩值和剪力值会显著下降,但其分布范围会增大;隧道最大正弯矩及最大剪力所在位置保持不变,不受隧道抗弯刚度值的影响,但最大负弯矩所在位置会随抗弯刚度的增大向隧道两端移动,当隧道剪切刚度超过抗弯刚度的20%时隧道位移、弯矩、剪力几乎均不再受剪切刚度的影响。所得结论可为类似工程提供一定理论支持。
Foundation pit unloading will create additional loads on the underlying existing tunnel.Based on the engineering practice,a semi-analytical solution considering the effect of foundation depth and tunnel shear effect is proposed to predict the longitudinal response of tunnel caused by the above excavation.A modified subgrade reaction coefficient considering different buried depth of tunnel is introduced,additional pressure induced by excavation is given based on the Mindin solution.By regarding the tunnel as a Timoshenko beam resting on the Pasternak foundation,the longitudinal deformations of the tunnel are analyzed.Compared with the three-dimensional finite element method and the measurements of the Jiusha river foundation pit crossing the No.1 metro line in Hangzhou,the accuracy of the proposed method is verified.The effects of bending stiffness and shear stiffness on the response of the tunnel are systematically analyzed.The results suggest that the mechanical response of tunnels could be better analyzed with the Timoshenko beam model.Increasing bending stiffness can effectively reduce the displacement,moment and shear of the tunnel,but increase the distribution range of them.At the same time,the increase of bending stiffness will not affect the location of maximum positive bending moment and the location of maximum shear force but will make the location of the maximum negative bending moment move toward both ends of the tunnel.When the shear stiffness exceeds 20%of the bending stiffness,the displacement and the bending moment,as well as the shear force of the tunnel,is hardly affected by the shear stiffness.The conclusions can provide some theoretical support for similar projects.
作者
徐日庆
程康
应宏伟
林存刚
梁荣柱
冯苏阳
XU Ri-qing;CHENG Kang;YING Hong-wei;LIN Cun-gang;LIANG Rong-zhu;FENG Su-yang(Research Center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou,Zhejiang 310058,China;Engineering Research Center of Urban Underground Development of Zhejiang Province,Hangzhou,Zhejiang 310058,China;Institue of Geotechnical Engineering Science,Hohai University,Nanjing,Jiangsu 210098,China;Norwegian Geotechnical Institute,Oslo 0806,Norway;Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China;Faculty of Engineering,China University of Geosciences(Wuhan),Wuhan,Hubei 430074,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2020年第S01期195-207,共13页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.41672264,No.41702313,No.41807262)
浙江省重点研发计划项目(No.2018C03G2010707)
