论文部分内容阅读
将颗粒离散元法应用到盾构隧道端头土体细观力学行为的模拟计算,探讨了砂土地层端头土体滑移破损的宏观现象和细观机理,分析了端头土体滑移破坏形态和位移场的演变,得到了端头土体颗粒内部的孔隙率、配位数及滑动接触数等细观特征.结果表明:端头土体的破损和颗粒位移场是渐进性发展的,起因于洞门土体颗粒的力链初始断裂,最终在土体内部形成明显的非连续位移梯度和剪切滑移面,并在洞门上方形成明显的地表沉降槽.剪切滑移区域内,颗粒细观特征变化明显,孔隙率因剪胀而增大,由初始的0.16左右增大到0.19~0.20;配位数由初始的4.1左右减小到3.0左右;力链因断裂而发生弯曲,方向由柱状逐渐变成环状;颗粒间滑动接触数由初始的0增大到0.20~0.28.说明,剪切滑移面右侧土体处于松动、滑移的非稳定状态,颗粒力链断裂、细小剪切裂纹连接、合并与贯通形成优势剪切滑移面.
The particle discrete element method is applied to simulate the meso-mechanics behavior of the soil at the end of the shield tunnel. The macro-phenomena and meso-mechanism of soil slip damage at the tip of sand soil layer are discussed. The morphologies and the displacement fields were obtained, and the mesoscale features such as porosity, coordination number and sliding contact number were obtained.The results show that the damage of the tip soil and the particle displacement field are evolving progressively , Resulting in the initial fracture of the force chain of the soil particles in Dongmen Formation and finally the formation of obvious discontinuous displacement gradient and shear slip surface in the soil and the formation of obvious surface sedimentation trough above the tunnel door. The microscopic features of the particles changed obviously. The porosity increased due to dilatancy from about 0.16 to 0.19 ~ 0.20. The coordination number decreased from about 4.1 to 3.0. Bending and direction gradually changed from columnar to ring; the number of sliding contact between particles increases from the initial 0 to 0.20 ~ 0.28, indicating that the soil on the right side of shear-slip plane is in a loose and slippery unstable state and the particle force Chain fracture, small shear-crack connection, merger and through-formation Potential shear slip plane.