摘要
地面沉降是当今危害较大的一种地质灾害问题,利用钻孔全断面分布式光纤监测技术监测地面沉降是一种有效的方法。光缆与土体的变形协调性是影响该技术准确获取地面沉降变形的重要因素。利用自主研发的离散元数值模拟软件MatDEM,建立了二维离散元光缆拉拔试验模型,探究了不同围压下光缆拉拔过程中光缆与周围土体的变形协调性问题。结果表明:二维离散元光缆拉拔模型能够准确反映光缆拉拔过程中的光缆应变分布和土体单元位移;不同围压下光缆拉拔力-拉拔位移曲线及应变分布曲线呈现出渐进式破坏模式;基于离散元方法获得的光缆滑脱深度,修正了光缆-土体变形协调系数。以苏州盛泽地面沉降数据为例,深入分析了不同围压和拉拔位移条件下了光缆-土体的变形协调性。该地区变形协调性较好的临界围压约为0.19 MPa,临界深度约为17 m。研究结果验证了离散元数值模拟方法在探究光缆-土体变形协调性方面的可行性,进一步论证了分布式光纤监测技术在地面沉降监测中的可靠性。
Land subsidence has been one of the main geological disasters with great harm. Full section monitoring of land subsidence borehole using distributed fiber optic sensing(DFOS) techniques has been proved to be an effective method. The deformation compatibility between cable and soil is a key factor which matters the land subsidence monitoring effectiveness. Using the discrete element numerical simulation software MatDEM, a 2D discrete element cable pull-out test model was established to explore the deformation compatibility between cable and the surrounding soil during pull-out under different confining pressures. The results show that the 2D discrete element cable pull-out tests model can accurately reflect the distribution of axial strain along cable and the displacement of soil element during the pull-out. The curves of pull-out force versus pull-out displacement and the distribution of axial strain along cable under different confining pressures show a progressive failure mode. Based on the slip depth of cable obtained by the discrete element method, the coefficient of cable-soil deformation compatibility is corrected. Moreover, the monitoring data of land subsidence in Shengze, Suzhou, was taken as an example to analyze the cable-soil deformation compatibility under different confining pressures and pull-out displacement conditions. The critical confining pressure is about 0.19 MPa and the critical depth is about 17 m in this region. The results verify the feasibility of the discrete element numerical simulation method in exploring the cable-soil deformation compatibility, and further demonstrate the reliability of DFOS in land subsidence monitoring.
作者
向伏林
杨天亮
顾凯
施斌
刘春
刘苏平
张诚成
姜月华
XIANG Fu-lin;YANG Tian-liang;GU Kai;SHI Bin;LIU Chun;LIU Su-ping;ZHANG Cheng-cheng;JIANG Yue-hua(School of Earth Sciences and Engineering,Nanjing University,Nanjing,Jiangsu 210023,China;Key Laboratory of Land Subsidence Monitoring and Prevention of Ministry of Land and Resources of China,Shanghai Institute of Geological Survey,Shanghai 201204,China;Nanjing Center,China Geological Survey,Nanjing,Jiangsu 210016,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2021年第6期1743-1754,共12页
Rock and Soil Mechanics
基金
国土资源部地面沉降监测与防治重点实验室开放基金(No.KLLSMP201702)
国家自然科学基金面上基金(No.41977217)
长江经济带地质资源环境综合评价(No.DD20190260)。
关键词
地面沉降
分布式光纤监测
变形协调性
离散元
MatDEM
land subsidence
distributed fiber optic sensing(DFOS)
deformation compatibility
discrete element
MatDEM
