为了研究影响泥水盾构开挖面上泥膜形成质量的主要因素,通过三维颗粒流程序(PFC3D)模拟了不同颗粒级配和不同密度的泥浆在泥浆压力作用下向不同孔径的地层中移动和泥膜的形成情况。模拟结果表明:增大泥浆d_(85)和泥浆密度有助于在地层表面形成良好的泥膜;地层孔径较大时,不易形成良好的泥膜,需要选择与之匹配的泥浆颗粒级配和泥浆密度。数值模拟得到了与室内试验一致的3种泥浆颗粒堆积形态:泥皮型、泥皮+渗透带型和渗透带型。当泥浆d_(85)与地层平均孔径Dp的比值d_(85)/D_p和泥浆密度较大时,堆积形态为泥皮型;当d_(85)/D_p和泥浆密度较小时,堆积形态为渗透带型。3种泥浆颗粒堆积形态中地层水压力从大到小排序为渗透带型、泥皮+渗透带型、泥皮型,而地层水平应力从大到小排序为泥皮型、泥皮+渗透带型、渗透带型。泥膜的支护机理为由泥浆和地层的水压力差对泥膜的作用力平衡地层的侧向土压力来保持开挖面的稳定。因此,形成的泥膜质量越好,泥膜的渗透系数就越小,泥膜处产生的水压力梯度就越大,可以提供的维持开挖面稳定的水平有效应力也就越大。影响泥膜形成质量的主要因素是泥浆颗粒级配、泥浆密度和地层孔径;在泥水盾构施工时,可以根据地层孔径调整泥浆颗粒级配和泥浆密度,使开挖面上能够形成良好的泥膜,从而保证开挖面的稳定。 In order to study the main factors that affect the quality of mud film formation on the excavation surface of slurry shield, the three-dimensional particle flow program (PFC3D) was used to simulate the migration and mud migration of mud with different particle sizes and densities into different pore sizes under mud pressure Film formation. The simulation results show that increasing mud d 85 and mud density can help to form a good mud film on the surface of the formation. When the formation pore size is large, it is not easy to form a good mud film, and the matching of the mud grain gradation and Mud density. Numerical simulation results show that there are three kinds of mud particle accumulation patterns in the laboratory experiment: muddy type, muddy type + infiltration type and infiltration type. When the ratio of d_ (85) to the average pore diameter Dp (d_ (85) / D_p and the mud density are large, the accumulation pattern is muddy type. When d_ (85) / D_p and mud density are small, Belt type. The order of formation water pressure in the three kinds of mud particle accumulation morphology is infiltration belt type, muddy permeability type and muddy type, and the horizontal stress of formation is in descending order of muddy type, muddy skin and permeable belt Type, permeability type. The supporting mechanism of the mud film is that the lateral earth pressure of the strata is balanced by the force of the water pressure difference between the mud and the strata on the mud film to keep the stability of the excavation face. Therefore, the better the quality of the mud film formed, the smaller the permeability coefficient of the mud film and the greater the gradient of water pressure generated in the mud film, and the greater the horizontal effective stress that can be provided to maintain the stability of the excavation face. The main factors affecting the quality of mud film formation are the mud particle size distribution, the mud density and the formation pore size. During the construction of slurry shield, the grading of mud particles and mud density can be adjusted according to the formation pore size so that a good mud can be formed on the excavation face Film, thus ensuring the stability of excavation surface.