山区斜坡中微型桩及油气管道变形机制模型试验研究

Model experimental study on deformation mechanism of micro piles and oil-gas pipelines in mountain slopes

为探究不同形式微型桩加固下的滑坡-管道系统相互作用机制和破坏演变过程,以西南山区天然气管道滑坡抢险工程为背景,开展注浆常规桩和注浆花管桩防护边坡的大型室内模型试验。以应变、土压力传感器和百分表对滑坡系统内结构物的相应指标进行监测,通过对桩体弯矩、土压力和桩顶位移数据进行分析。研究结果显示,在滑坡体系中,由桩、滑体和管道组成的系统在滑坡发育中的变化具有协调一致性,变形可分为4个阶段:初始阶段、均匀变形阶段、快速变形阶段和破坏阶段。微型桩主要以发生在滑带附近的弯剪破坏为主,在滑带附近,桩前土压力达到最大值,花管桩以滑带为轴具有旋转趋势,导致桩底产生较大的土压力。弯矩大小整体上呈现出“S”形曲线分布,并且由于桩顶承台的联系作用,桩体上部产生较大弯矩。花管桩一侧由注浆形成的桩土复合结构能更好地抵抗滑坡推力,桩体达到极限强度并破坏之后,复合结构仍然能起到一定的抗滑作用。通过多元融合数据分析,观察到管道变形发生时间较晚,为抢险工作提供了时间窗口。管道主要表现为受弯破坏和挤压破坏,接口位置为管道防护的薄弱点。微型桩在山区油气管道防护中具有重要的应用潜力,进一步的研究和改进对微型桩在滑坡治理中的应用具有积极作用。

To investigate the interaction mechanisms and failure evolution processes of landslide-pipeline systems under different forms of micro-pile reinforcement,large-scale indoor model tests were conducted using grouting conventional piles and grouting flower tube piles for slope protection in the Southwest mountainous region,with a focus on the emergency rescue project of a natural gas pipeline landslide.Strain gauges,soil pressure sensors and dial gauges were used to monitor the corresponding indicators of the structural elements within the landslide system,and analysis was performed on the data of pile bending moments,soil pressures and pile head displacements.The results showed that the system consisting of piles,sliding masses and pipelines in the landslide exhibited coordinated changes during the development of the landslide,with deformation occurring in four stages:initial stage,uniform deformation stage,rapid deformation stage and failure stage.Micro-piles primarily experienced bending and shear failure near the sliding belt.Near the sliding belt,the soil pressure in front of the piles reached its maximum value,and the flower tube piles exhibited a rotational trend with the sliding belt as the axis,resulting in significant soil pressures at the pile base.The magnitude of bending moments exhibited an overall“S-shaped”curve distribution,and due to the interaction with the pile cap,larger bending moments were generated in the upper part of the piles.The pile-soil composite structure formed by grouting on one side of the flower tube piles better resisted the landslide thrust.Even after the piles reached their ultimate strength and failed,the composite structure still provided a certain degree of resistance against sliding.Through multidimensional integrated data analysis,it was observed that the deformation of the pipeline occurred later,providing a time window for emergency rescue work.The pipeline mainly experienced bending failure and compression failure,with the interface position being the weak point in pipeline protection.Micro-piles have significant potential for applications in the protection of oil and gas pipelines in mountainous regions,and further research and improvement play a positive role in the application of micro-piles in landslide control.