静/动载作用下埋地管道力学性能的试验分析

针对埋地管道开展了静载和循环荷载试验,综合分析了荷载类型、加载角度、管道外径和管道材质等因素对管道力学与变形性能以及管周土压力分布规律的影响。结果表明:静载作用下,管周土中垂直土压力大小与加载位置关系密切,水平土压力受“土拱效应”影响显著;管道呈现水平向外鼓胀、垂直径向压缩的椭圆状变形,且承压板荷载越大,管道变形越严重,同时管顶“土拱效应”越显著。循环荷载对埋地管道上方土层的沉降影响明显大于静载;改变承压板角度时效果差异明显,当加载范围关于管道轴线对称时埋地管道所受影响显著。对比不同外径和材质的埋地管道,发现当厚径比相同时,管径越大,壁厚越大,弹性模量也越大,管道的抗变形性能也就越好;公称压力相同时,聚丙烯管道抗变形能力强于外径相等的高密度聚乙烯管道。

Experimental Study on Mechanical Performance of Buried Pipes

Through experiments considering static and cyclic loading on buried pipes, the effect of loading types, load plate angle, the pipe outer diameter, and the material of pipe on mechanical and deformation properties of buried pipe and distribution characteristics of earth pressures around pipes was presented. The results show that under the static load, earth pressure of the soil below the loading plate is affected significantly. The vertical earth pressure is closely related to the loading position, and the horizontal earth pressure is apparently affected by the soil arching effect. The pipe’s horizontal deformation is outward bulging, and vertical deformation is radial compression. Just like an ellipse, and the load of the bearing plate is larger, the deformation of pipe is more serious, meanwhile, the soil arching effect above the pipe is more obvious. Long term effect of cyclic loading on buried pipe is apparently greater than that of static load, and the forms of soil settlement under these two kinds of load are different. Changing the loading angle of the bearing plate, the difference of results is obvious. When the loading range is symmetrical about the pipe axis, the buried pipe is affected significantly. Comparing buried pipes, which are different diameters and material, it is found that when thickness to diameter ratio is the same, the larger the diameter, the greater the wall thickness, and the elastic modulus is latger, the better the deformation resistance of pipe is. When the nominal pressures are same and the outer diameters are equal, polypropylene pipe has a better anti deformation ability than that of high-density polyethylene pipe.