崩塌落石冲击埋地油气管道的动力响应机理研究

STUDY ON DYNAMIC RESPONSE MECHANISM OF ROCKFALL IMPACTING BURIED OIL AND GAS PIPELINE

高位崩塌落石是造成长输埋地油气管道破坏的主要地质灾害之一。本文通过111处山区管道崩塌案例分析,归纳出崩塌与埋地管道相互作用的3种模式:冲砸管道、牵引管道及埋没管道,其中冲砸管道的危害性最大,并建立了崩塌与管道相互作用的地质力学模型。采用有限元仿真软件系统模拟了落石冲击、土体与管道变形响应过程及影响因素,发现落石冲击管道的作用过程是一个瞬态过程、持续时间约0.1 s,揭示了土体和管道动态响应规律及管土相互作用机理,发现管土变形经历了从协调变形到非协调变形的发展演化过程。在此基础上通过不同的落石速度、管道埋深、内压、落石形状以及防护工程等影响因素分析,提出了崩塌区管道防护设计建议,管道埋深设计2.0 m以上、盖板厚度不小于0.2 m,可有效降低管道遭受落石冲击破坏的风险。

High level rockfall is one of the main geological disasters causing the damage of long-distance buried oil and gas pipelines.Based on the analysis of 111 mountain pipeline collapse cases,this paper summarizes three modes of interaction between collapse and buried pipeline,Smashing pipeline,traction pipeline and buried pipeline.Among them,smashing the pipeline is the most harmful.And the geomechanical model of the interaction between collapse and pipeline is established.The response process and influencing factors of rockfall impact,soil and pipeline deformation are simulated by the finite element simulation software.It is found that the rockfall impact process is a transient process with a duration of about 0.1 s,which reveals the dynamic response law of soil and pipeline and the pipe-soil interaction mechanism.The pipe-soil deformation can experience the development and evolution process from coordinated deformation to uncoordinated deformation.On this basis,through the analysis of influencing factors such as different rockfall velocity,pipeline buried depth,internal pressure,rockfall shape and protection engineering,some suggestions on pipeline protection design in collapse area are put forward.The buried depth of the pipeline is designed to be more than 2.0 m and the thickness of the cover plate is not less than 0.2 m,which can effectively reduce the risk of rockfall impact damage to the pipeline.