新型排水用轴向中空壁聚氯乙烯埋地管力学性能试验及数值分析

Mechanical properties test and numerical analysis of new axialhollow-wall PVC buried pipe for drainage

为了研究埋地轴向中空壁塑料排水管的变形与力学响应特性,以便充分利用材料与结构性能,基于模型箱试验,获得埋地管道受到土荷载、地面荷载和管土相互作用下管道及其管周土体的力学及其变形特性;基于ABAQUS有限元分析管截面在埋地外压、排水内压及两者组合作用下的应力和变形特性,建立管道的基本力学参数在砂箱试验与真实埋地条件下的换算关系,提出边界效应修正计算公式。研究结果表明:土柱法+分布角法适用于计算地面静荷载作用下埋地结构壁管道的管顶竖向压力,荷载扩散角宜取30°~35°;在地面静荷载作用下,管道径向变形计算方法中Spangler-Iowa公式偏保守,AWWA M23规范计算结果与试验结果较吻合,而考虑准永久值系数会导致变形计算结果偏小;在埋土外压作用下,管腰位置内壁易发生受压破坏;排水时,管顶位置内壁易发生受拉破坏;内外壁起主要承载作用,受力较大;中间筋主要起连接作用,受力时应力以中性轴为零点向两侧呈梯度增加;本文提出的边界效应修正计算公式是准确可行的。研究成果可为轴向中空壁塑料管等柔性埋地管道的结构设计、力学和损伤失效分析提供参考。

In order to study the deformation and mechanical response characteristics of buried Axial hollow-wall plastic drainage pipe,and achieve full utilization of materials and structures,based on the model box test,the mechanical and deformation characteristics of the buried pipeline and the soil around the pipeline under the soil load,ground static load and pipe-soil interaction were obtained.Based on ABAQUS finite element,the stress and deformation properties of the pipe cross section under the action of buried external pressure,drained internal pressure,and the combination of both were analyzed.The conversion relationship equation between the basic mechanical parameters of pipeline under sandbox test and real buried conditions was established.The results show that the soil column method combined with distribution angle method is suitable for calculating the vertical pressure of the pipe top under the static load of the ground,and the load diffusion angle should be 30°−35°.Under static ground loads,the Spangler-Iowa formula in the calculation method of pipeline radial deformation is conservative,and the results calculated by the AWWA M23 specification are in good agreement with the test results.Considering the quasi-permanent value coefficient will lead to a smaller deformation calculation result.Under the external pressure of buried soil,the inner wall of the pipe waist position is prone to compression failure.During drainage,the inner wall at the top position of the pipe is prone to tensile damage.The inner and outer walls play a major load-bearing role and are subjected to significant forces.The intermediate rib mainly plays the role of connection,and the stress increases in a gradient from the neutral axis to both sides when subjected to force.The proposed correction formula for calculation boundary effect is correct and feasible.The research results can provide reference for the structural design,mechanical and damage failure analysis of flexible buried pipelines such as axial hollow wall plastic pipes.