摘要
悬索桥重力式锚碇边坡的长期变形与稳定性是影响该类桥梁结构正常使用的一个关键要素。为合理讨论这一问题,以泸定大渡河桥康定岸重力式锚碇边坡为例,首先开展了现场边坡土体剪切、压缩试验,通过三维弹塑性数值模拟方法确定坡体应力场,基于此确定直剪蠕变试验加载条件,进而针对主要由冰碛土构成的该坡体,进行直剪蠕变试验,根据试验结果揭示的土体蠕变特性随时间逐渐减弱的特征,结合Mohr-Coulomb强度准则,采用Burgers体与广义Kelvin体组成的两时段蠕变本构模型进行锚碇边坡的黏弹塑性分析。考虑锚碇发挥正常使用功能的要求,提出了特征点(散索鞍点)位移容许值判据,将强度折减法扩展应用于黏弹塑性坡体的长期变形与稳定性分析。实例分析表明,该锚碇在正常运营100a时散索鞍点朝河侧水平位移为13.91 cm,在正常使用极限状态的条件下,锚碇边坡的长期稳定系数为1.71。
The long-term deformation and stability of gravity anchorage slope is one of the most important problems affecting the natural serviceability of the suspension bridge engineering. In order to discuss the problem reasonably,the gravity anchorage slope on Kangding Bank of Dadu River Bridge in Luding is taken as an engineering example.Firstly,in-situ shear and compression tests of the slope soil are carried out. The stress field of the gravity anchorage slope is obtained with three-dimensional elastoplastic numerical simulation method. Based on these results,the loading conditions of the direct shear creep test are determined. Then the direct shear creep test is carried out for the slope mainly composed of moraine soil. The creep test results show creep behaviour of the moraine soil decreases with time. In light of the creep characteristics of the soil,time-dependent combination constitutive models consist of Burgers and general Kelvin model individually with Mohr-Coulomb strength principle is proposed and applied in visco-elastic-plastic numerical simulation analysis of the slope. Considering the requirements of natural serviceability of the anchorage,the criterion of allowable displacement at its unique point( saddle point of the anchorage) is applied. The shear strength reduction method for long-term deformation and stability analysis of the slope is also used. The results of the practical example obtained using the present method show horizontal displacement towards the river of the saddle point is 13. 19 cm when the anchorage-slope system has naturally served for 100 years. The long-term stability coefficient of the system is 1. 71 to meet the requirement of its natural serviceability limit state.
作者
陈廷君
肖世国
程强
周火明
CHEN Tingjun;XIAO Shiguo;CHENG Qiang;ZHOU Huoming(1Department of Geological Engineering,Southwest Jiaotong University,Chengdu 610031;Key Laboratory of High-speed Railway Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu 610031;Sichuan Provincial Transport Department Highway Planning,Survey,Design and Research Institute,Chengdu 610041;Chongqing Branch,Yangtze River Scientific Research Institute,Chongqing 400026)
出处
《工程地质学报》
CSCD
北大核心
2019年第3期632-639,共8页
Journal of Engineering Geology
基金
国家自然科学基金项目(51578466)
四川省交通运输科技项目(2013 A1-3,2014-C-1)资助~~
关键词
重力式锚碇
冰碛土
直剪蠕变试验
数值模拟
边坡长期稳定性
Gravity anchorage
Moraine soil
Direct shear creep test
Numerical simulation
Long-term stability of slope
