【摘要】 针对城市地下空间开发过程中经常出现的基坑工程漏水漏砂引发的灾害问题,利用离散元和计算流体力学耦合的方法(DEM-CFD方法)对灾害的发展过程进行数值模拟分析。在室内试验、平面双轴数值模型、渗流模型的基础上确定了土体和流体的细观参数,建立数值模型,模拟研究两类典型地层(富水砂层、富水砂层上覆黏土层)发生漏水漏砂后的地层变形规律、土体损失规律以及地应力场发展变化规律。研究结果表明,对于富水砂层,漏水漏砂后基坑外部地表形成沉降槽,地表沉降最大值与地层损失率成正相关;地下水一方面加速土体的流失,另一方面使地层发生朝向漏点的集中运动。对于富水砂层上覆黏土地层,存在使地表拉裂的临界地层损失率,且上覆黏土层越厚,临界地层损失率越大;根据漏水漏砂后的地层应力状态可将地层分为空洞区、松动区、主拉应力区以及复杂应力区。研究成果对于基坑工程漏水漏砂灾害的治理与精细化控制具有参考意义。更多还原

【Abstract】 With the large-scale development of underground space,the hazards induced by leakage of groundwater and sand in excavations occur frequently. DEM-CFD method was adopted to simulate the process of this kind of hazard. The microscopic parameters of soil and fluid were determined based on laboratory tests,biaxial model of the particle flow code and seepage model. A numerical analysis model was developed to research the laws of ground movement,ground loss and ground stress field due to the leakage of groundwater and sand. Two typical strata including water-rich sand stratum and water-rich sand layer overlying clay stratum were considered. The results show that,for the water-rich sand stratum,the leakage of groundwater and sand induces a settlement trough on the ground surface outside the excavation,the maximum value of ground surface settlement is proportional to the soil mass loss ratio,and the leakage of groundwater accelerates the ground loss and results in the concentrated movement of ground towards the leakage point. It is also indicated that,for the water-rich sand layer overlying clay stratum,there exists a critical soil mass loss ratio leading to the crack of the ground surface,and the thicker the clay layer,the greater the critical soil mass loss ratio is. Furthermore,the ground around the leakage point could be divided into hollow area,loose area,main tensile stress area and complex stress area. The results of the research provide a reference for the hazard control and delicacy management during the leakage of groundwater and sand in excavations.更多还原