荷载作用下砂土边坡-管道相互作用试验研究

Experimental study of sandy slope-pipe interaction under loading

随着我国西气东输、南水北调等重大工程的快速推进,埋地管道不可避免地会穿越高陡山区,并受到区域地形地貌的影响,而关于边坡-管道相互作用机制的认识还相对滞后,相关研究亟需加强。基于分布式光纤应变传感(distributed strain sensing,简称DSS)、粒子图像测速(particle image velocimetry,简称PIV)技术,开展加载工况下砂土边坡-管道相互作用的室内模型试验,探究了临坡地基极限承载力的影响因素,并研究了不同坡角下边坡土体变形破坏机制及埋地管道的结构响应特征。研究结果表明:(1)临坡地基经历了弹性压密、局部剪切和整体破坏3个阶段,并呈现不对称楔形破坏模式;(2)临坡地基极限承载力随着坡角的增大呈减小趋势,同一坡角下埋地管道的存在会降低临坡地基极限承载力;(3)管道对边坡滑裂面形成路径的影响程度随着坡角的增大而变大;(4)在荷载作用下埋地管道横截面环向应变呈“椭圆化”分布,据此提出了管周界面土抗力的简化计算模型与椭圆度计算式。相关结论对边坡-管道系统的变形控制与结构设计有一定的参考和借鉴意义。

With the rapid development of key projects in China,such as West-to-East Gas Transmission and South-to-North Water Diversion,buried pipelines will inevitably pass through the mountainous area and are affected by regional topography and landforms.However,the interaction mechanism between slope and pipelines is still relatively unclear.In this study,the model tests on sandy slope-pipe interaction under loading are carried out in laboratory based on distributed strain sensing(DSS)and particle image velocimetry(PIV)technologies.The factors influencing the bearing capacity of the foundation are investigated.The failure characteristics of the slope and the structural responses of the buried pipeline are also explored.The research results show that:(1)The slope foundation has undergone three stages:elastic compaction,local shear and overall destruction.The foundation shows asymmetrical wedge-shaped failure pattern.(2)With the increase in slope angle,the ultimate bearing capacity of the foundation decreases.Under the same slope angle,the presence of pipeline reduces the ultimate bearing capacity of the slope foundation.(3)With the increase in slope angle,the influence of the pipeline on the slope failure mechanism increases.(4)Under the loading of the slope,the circumferential strain in the cross-section of the buried pipe is“elliptically”distributed,and an ellipticity calculation formula and a simplified calculation model of the soil resistance around the pipe circumference are proposed.This study can provide a reference for the deformation control and structural design of buried pipelines in sandy slopes.