地层沉陷过程中埋地高密度聚乙烯(HDPE)管道力学行为研究  

Mechanical response of buried HDPE pipes subjected to localized land subsidence

作　　者：周敏[1,2] 杜延军[1,2] 王非[1,2] 尤佺[1,2] 董冬冬[1,2] 

机构地区：[1]东南大学岩土工程研究所,江苏南京210096 [2]东南大学江苏省城市地下工程与环境安全重点实验室,江苏南京210096

出　　处：《岩石力学与工程学报》2017年第A02期4177-4187,共11页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51278100;41472258);东南大学优秀博士学位论文培育基金资助(YBJJ1632)~~

摘　　要：地层沉陷的发生和发展会导致管道的不均匀沉降变形,进而造成破坏失效。现有研究成果大多基于Winkler弹性地基梁理论进行地层沉陷作用下埋地管道受力变形的分析,这一理论适用的前提是"管土始终接触"。然而由于管土的刚度差异以及管道上方填土的土拱效应,可能出现"管土分离",致使Winkler弹性地基梁理论的适用性值得商榷。因此,需要以试验数据为基础,证实"管土分离"现象的存在,并研究此种状态下管道的受力变形变化规律。利用自制的大型模型试验箱,以长江砂为填料,通过下调控制模型箱底板的不同位移模式模拟地层沉陷的形成和发展,进而研究埋地HDPE双壁波纹管道的受力变形特征。试验结果表明:(1)在模型箱底板的下调过程中,HDPE管道及其填土表面的竖向位移均符合修正高斯分布曲线,且管道竖向位移曲线的宽度系数小于填土表面竖向位移曲线的宽度系数;(2)HDPE管道的上覆土压力在模型箱底板的下调过程中总体呈现出增加的趋势,并呈现出"三维土拱效应"的变化特征;(3)管道下方土压力测试数据证实了地层沉陷发展过程中的"管土分离"现象,而Winkler弹性地基梁理论由于采用了"管土不分离"的假定,其对于埋地管道竖向位移以及其纵向弯矩的计算过于保守,其管道竖向位移的计算值是本文实测值的1.1~9倍,纵向弯矩的计算值是实测应变计算值的3~11倍。The failure of buried HDPE pipes may occur as a result of large differential deformation caused by the localized land subsidence.The buried pipe subjected to the land subsidence is commonly analyzed using the theory of beams on Winkler elastic foundation.The theory assumes that the pipe deforms with soil and no separation is expected.However,separation of the pipe and soil may occur due to the stiffness difference and the soil arching effect triggered above the pipe when the land subsidence is developed.Therefore,it is necessary to investigate the possible ＂pipe-soil separation and performance of the pipe under this condition.In this study,series of large-scale model tests are conducted to investigate the mechanical responses of buried HDPE pipes by using a custom-made model box.Yangtze River sand is used as the backfill.Movable plates installed at the bottom of model box are lowered in target sequences to simulate the land subsidence.Test results show that（1） the vertical displacement of HDPE pipes and settlement trough at the soil surface are well fitted by using the modified Gaussian distribution curves.The width parameters of fitted curves for vertical displacement of HDPE pipes are smaller than those for settlement trough at the soil surface;（2） the earth pressure at the top of the HDPE pipe experiences an overall increase with lowering of bottom plates of the model box.Three-dimensional soil arching effect is observed during the test;（3） the earth pressures measured underneath the pipe reduce to zero with the lowering of the bottom plates.It is indicated that the pipe-soil separation occurs at the bottom of the pipe.It is also found that the vertical displacement and longitudinal bending moment of the HDPE pipe calculated by the theory of beams on Winkler elastic foundation are 1.1 to 9 times and 3 to 11 times those measured in this study,respectively.

关 键 词：土力学 地层沉陷 HDPE双壁波纹管道 模型试验 土压力 管道变形 管土分离 

分 类 号：TU432[建筑科学—岩土工程]