落石冲击荷载作用下埋地PCCP应力应变响应

Stress-strain Response of Pre-stressed Concrete Cylinder Pipe under Rockfall Impact Load

针对影响预应力钢筒混凝土管(PCCP)安全运行的落石冲击问题,以实际工程为原型,利用有限元理论建立了球形落石冲击埋地PCCP的“石-土-管”模型,在完成静力荷载工况计算的基础上,模拟落石冲击埋地PCCP的过程。通过改变落石半径、落石高度,分析不同落石冲击荷载作用下管道的应力和塑性应变规律。研究结果表明:落石冲击对PCCP的破坏主要为环向受拉塑性破坏;相比于落石高度,落石半径的改变对PCCP的影响更大;10m的悬空高度下,半径超过1.4 m的落石将会使混凝土管芯产生超过16.0×10^(-4)的塑性应变,砂浆产生超过9.1×10^(-4)的塑性应变,导致材料出现可见裂缝;冲击荷载对PCCP各部件的破坏顺序是混凝土管芯、砂浆、钢筒和预应力钢丝,且在混凝土管芯开裂后,钢筒和预应力钢丝的Mises应力将会迅速增大并屈服破坏。

A finite element model of rockfall-soil-pipe was established to study the influence of rockfall impact on the safe operation of Prestressed Concrete Cylinder Pipe(PCCP).The process of spherical rockfall impact on buried PCCP was simulated on the basis of the calculation of static load condition.By changing the radius and height of rockfall,the stress and plastic strain of pipeline under different rockfall impact loads were examined.Results demonstrated that PCCP under rockfall impact mainly suffered from circumferential tensile plastic damage.Compared with the height of rockfall,the change of rockfall radius had a greater influence on PCCP.At a suspension height of 10 m,the falling rock with a radius over 1.4 m would cause visible cracks in the material with the plastic strain of concrete tube core exceeding 16.0×10^(-4) and the plastic strain of mortar over 9.1×10^(-4).Under rockfall impact load,concrete tube core first witnessed damage,and then mortar,steel tube,and prestressed steel wire in sequence.After the crack of concrete tube core,steel tube and prestressed steel wire saw rapid increase and yield failure of Mises stress.