地表载荷对硬岩区埋地管道应力应变影响分析

Analysis on influence of surface load to stress-strain characteristics of pipeline buried in hard rock region

为研究地表载荷对硬岩区埋地管道力学性能的影响,建立了管-土耦合三维数值模型,分析了地表载荷大小、作用面积、管道压力、管道径厚比及回填土弹性模量对管道应力分布、塑性应变、椭圆度的影响。结果表明：地表压载作用下,高应力区首先出现在管道顶部且呈椭圆形;随着地表载荷及其作用面积的增大,管道高应力区逐渐扩大,管道截面左右两侧也出现应力集中;随着回填土弹性模量、管道壁厚及内压的增加,管道顶部高应力区及最大等效应力均减小。塑性应变首先出现在管顶,且塑性区随地表载荷、载荷作用长度增加而增大,随回填土体弹性模量及管道壁厚增大而逐渐减小;当内压为0～4MPa时,管道塑性应变及塑性区随内压的增大而减小。管道椭圆度随回填土体弹性模量、管道内压、壁厚增加而逐渐减小,随地表压载增大而增大。

In order to study the influence of surface load on mechanical performance of pipeline buried in hard rock region,a pipeline- soil coupling 3D numerical model was built. The influences by magnitude of surface load,action area,inner pressure,radius- thickness ratio of pipeline and elasticity modulus of backfill soil on stress distribution,plastic strain and ovality of the pipeline were analyzed. The results showed that under the action of surface load,the high stress zone,which is oval,appears on the upside of the pipeline. With the increasing of surface load and force area,the high stress zone enlarges gradually,and the stress concentration appears on the left and right sides of the cross section in the pipeline. With the increasing of elasticity modulus of backfill soil,thickness and inner pressure of pipeline,the high stress zone shrinks,and the maximum equivalent stress decreases. The plastic strain zone appears on the upside of pipeline firstly,and it increases with the increasing of surface load and action length,but decreases with the increasing of elasticity modulus of backfill soil and thickness of pipeline. The plastic strain and plastic zone of pipeline decrease with the increasing of inner pressure when the inner pressure ranges from0 to 4 MPa. The ovality of pipeline decreases with the increasing of elasticity modulus of backfill soil,thickness andinner pressure of pipeline,but increases when the surface load increases.