复合地基若干问题的数值模拟分析-numerical simulation analysis of several problems in composite foundation.docx

摘要CFG 桩是水泥粉煤灰碎石桩的简称，它是由水泥 、粉煤灰、碎石、石屑和砂加水拌 和形成的高粘结强度桩，和桩间土、褥垫层一起形成复合地基。CFG 桩具有施工速度快、 工期短、质量容易控制及工程造价低廉等特点。CFG 桩复合地基是软土地基处理中的一 种较为有效的方法, 近年来得到广泛的应用。 本文完成的主要工作和主要结论如下： (1)通过 ANSYS 有限元程序对 CFG 桩复合地基边(护)桩效应进行分析，讨论边(护) 桩对 CFG 桩复合地基沉降、土体应力和承载力的影响。分析表明由于边(护)桩的存在, 限 制了桩间土体的侧向挤出, 减小了土体的竖向位移。同时,边(护)桩增大了附加应力影响 范围, 能够在一定程度上提高复合地基的承载力，并促进了桩间土承载潜力的发挥。 (2)通过对边(护)桩的布置进行调整，如增加边(护)桩的排数，设置一排边(护)桩时， 调整单排边(护)桩距承台的距离或延长单排边(护)桩的长度等等，进一步利用 ANSYS 进 行分析，从而得出在不同的边 (护)桩的布置情况下其对承载力、沉降影响。分析表明在 其他条件不变的情况下，随着边(护)桩的排数增加，CFG 桩复合地基的承载力将有所提 高，而沉降则相应的减小。但排数达到两排以上时对承载力、沉降的贡献将相应的减小。 而在设置一排边(护)桩时，缩短单排边(护)桩距承台的距离或延长单排边(护)桩的长度， 此时承载力将有所提高，沉降则相应的减小。(3)通过 ANSYS 有限元程序对 CFG 桩复合地基在地震荷载作用下进行分析，当调整 承台与褥垫层之间的摩擦系数时，分析地震对上部结构影响的变化。通过分析研究表明 CFG 桩复合地基在地震作用下上部结构的震动位移会随着摩擦系数的增大而减小，而上 部结构的顶层与底层位移差则是随着摩擦系数的增大而变大。 关键词：CFG 桩复合地基；边(护)桩；有限元；地震 AbstractThe CFG pile is the shorter form of cement - fine coal -gravel pole. It is the highly adhesive strength pile which is composed of cement、gravel、screenings and sand by blendingwater, and formats composite foundation with inter-pile soil and bedding course layer. High construction speed、short project time、being easy to control quality and low construction cost characterize the CFG pile. CFG composite foundation is an effective method of handling softground and is widely applied in recent year.Main job and conclusion of the book is accomplished as follows:Analyzing the side-pile effect of CFG composite foundation by finite element analysis program , discuss the effect of subsidence、stress in soil mass and bearing capacity of the side-pile to CFG composite foundation. The analysis indicates that the side-pile confine theextrusion of soil and diminish vertical displacement. At one time, side-pile augment the effective extension of additional stress, could enhance bearing capacity and promote exertion of the bearing potential of the soil among the piles.By adjusting the arrangement of the side (protect) pile, for instance, increases thenumber of the side (protect) pile, adjusts th