基于物质点法的盾构隧道涌水涌砂模拟与应用

Simulation of Water-Soil Gushing in Shield Tunnel Based on Material Point Method and Its Application

为避免有限元方法模拟大变形时遇到网格畸变等限制,采用两相单点物质点法研究隧道涌水涌砂的演化机制及其对周围土体水力-土力学行为的影响规律。经砂土渗漏模型试验验证后,将该方法应用于某工程案例中,并结合监测数据分析地表沉降的发展、土体应力场和孔压场的演化等。在涌水涌砂作用下周围土体位移场可分为流动区、扰动区和静止区3个区域。利用流动区的发展可以揭示隧道涌水涌砂的影响,并将涌水涌砂过程分为初始、快速发展和稳定3个阶段。在初始涌砂阶段及时发现并采取控制,能够最大程度地降低涌水涌砂对周围土体的影响。最后,参数分析结果发现:隧道涌砂位置越高,砂土流失速率越快,在快速发展阶段对地层的影响越大;隧道涌砂位置越低,在稳定涌砂阶段产生的最终流动区面积越大,对土体应力场的影响也越大。

To avoid the limit of grid distortion when using a finite element method to simulate large deformation,a two-phase single-point material point method is employed to examine the evolution mechanism of water-soil gushing around shield tunnel and its influence laws on the hydro-mechanical behavior of soil.The proposed method is verified using a sand leakage model experiment and then applied in an engineering case.Based on the monitoring data,the development of ground settlement,the evolution of stress field,and pore pressure field in soil are analyzed in this study.With respect to water-soil gushing,the displacement field of the surrounding soil can be classified into three zones:flow,disturbed,and stationary zones.The development of the flow zone can help determine the influence of water-soil gushing.The process of water-soil gushing can be classified into three stages:initial,rapid developing,and stable stages.The influence of water-soil gushing on surrounding soil can be minimized by its timely detection and implementation of appropriate control measures at the initial stage.Finally,the parameter analysis results reveal that:the higher the gushing point location,the faster is the sand loss rate and the greater is the impact on the soil layers in the rapid developing stage;the lower the gushing point location,the larger is the final flow zone after the stable stage and the greater is the influence on the soil stress field.