超长水泥土搅拌桩的荷载传递特性

大型构筑物实体下超长水泥土搅拌桩的桩身应力和变形观测结果表明,对桩身质量良好的水泥土桩,在长期荷载作用下呈现出接近刚性摩擦桩的荷载传递特性和较高的桩土应力比,并且,只要桩身中下部水泥土强度有保证,群桩中桩身轴力的有效传递深度可达25m以上.     

水泥土搅拌桩承载力计算方法探讨

针对水泥土室内拌制的强度很高、现场拌制的强度很低的情况产生的搅拌桩工程事故 ,提出了按现场水泥土强度设计的思想 ,从而避免了按室内拌制水泥土强度进行设计而和现场施工质量脱节的弊端。此外 ,也克服了超长水泥土桩因静载荷试验影响深度有限而得出不合实际的承载力的情形     

水泥搅拌桩复合地基作为重力式挡墙基础的应用

当前,水泥搅拌桩技术在处理深层软基的工程中应用非常广泛。在实际工程中,水泥搅拌桩主要以形成复合地基的形式提高软土地基的承载力,从而使地基承载力达到各类工程所需的地基承载力要求。本文以泉州市丰泽区浔美工业区45号路重力式挡墙的深层软基处理为例,阐述水泥搅拌桩复合地基作为重力式挡墙基础的应用。     

水泥搅拌桩承载力现场试验研究

通过水泥搅拌桩地基的载荷试验,准确地评价该地区承载力,同时对有效桩长、桩间土承载力发挥系数和利用载荷试验确定该地区的承载力标准值进行探讨。     

水泥深层搅拌桩支护基坑的设计与施工

介绍用深层搅拌桩支护基坑的设计与施工方法.深层搅拌桩在我国建筑工程中不仅用于地基加固,而且在基坑支护中也得到了广泛应用.但当地基情况太差,基坑较深或场地较窄时,该工法就受到一定限制.笔者通过多次学习与实践,认为增加槽底加固桩可扩大其使用范围,并可大幅度降低工程造价.     

水泥土搅拌桩变掺量施工工艺研究

基于对在上部荷载作用下复合地基中水泥土搅拌桩桩身应力分布特征的认识,对水泥土搅拌桩处理深厚软土地基,提出了沿桩身改变水泥掺量的施工工艺。通过在某软土地基进行试桩和对桩身质量的检测,研究了利用该工艺改善水泥土搅拌桩质量的施工方法。研究结果表明,采用变掺量施工工艺可提高水泥土搅拌桩的上部桩身强度,对于较长的水泥土搅拌桩,可改善搅拌桩的整体成桩质量,而且该施工工艺符合上部荷载作用下桩的受力特性。     

深层水泥搅拌桩加固永嘉软土的探讨

通过对深层水泥搅拌桩的检测分析和具体的工程实例，探讨水泥搅拌桩对永嘉软土地基加固的适宜性及存在的问题。     

土钉与水泥搅拌桩组合支护施工质量监控

结合泉州市鑫亿大厦工程实例,介绍了一种改良的组合支护形式-土钉和水泥搅拌桩组合支护体系在特殊地质条件下的应用,并总结了施工、监测经验。     

深层搅拌桩复合地基在某小区住宅工程中的应用

通过工程实例,介绍了深层搅拌桩施工工艺,阐述了施工技术和质量控制措施。     

湿法双轴双向深层水泥搅拌桩施工技术研究

随着经济的发展,深层搅拌桩施工法在高速公路、隧道、市政设施以及建筑基坑工程中的应用越来越多,特别是在高速公路的路基处理中应用较多,但多为粉喷桩。湿法深层搅拌桩近年才开始应用,而湿法双轴双向深层搅拌桩则应用的更少。通过该项技术的研究,获取了湿法双轴双向深层搅拌桩的各项技术参数,并将研究成果成功应用于软土地基的加固施工,地基承载力大幅提高,为高架桥的施工提供了交通导改条件,促进了工程整体施工的顺利进行。     

基桩在水平和竖向荷载作用下的受力分析

在水平和竖向荷载的共同作用下,基桩与土体之间的相互作用是一个三维空间的问题。本文通过综合分析,采用层状横向各向同性弹性半空间地基模型,利用有限元-有限层法,并考虑P-Δ效应对桩身内力的影响,对基桩的P-Δ效应进行了分析。     

External Stability of Group Column Type Deep Mixing Improved Ground Under Embankment Loading

The Deep Mixing Method (DMM), a deep in-situ soil stabilization technique using cement and/or lime as a binder has been often applied to improve soft soils. Group column type improvement has been extensively applied to foundations of embankment or lightweight structures. A design procedure for the group column type DM ground has been established in Japan mainly for application of embankment, in which two failure patterns are assumed: sliding failure in the external stability and rupture breaking failure in the internal stability. The internal stability of the improved ground has been investigated experimentally, and it was found that the DM columns show various failure modes: shear, bending and tensile failure, depending not only on the ground and loading conditions but also on the location of each column. However, the current design does not incorporate the effects of these failure modes, but only that of shear failure mode. For the external stability, it is known that a collapse failure pattern, in which the DM columns tilt like dominos, could take place instead of sliding failure. The current design method, which does not take into account this failure pattern, might overestimate the external stability. In this study, a series of centrifuge model tests and elasto-plastic FEM analyses were performed to investigate the external stability of group column type DM improved ground under embankment loading. The centrifuge model study has revealed that the improved ground does not fail with a sliding failure pattern but with a collapse failure pattern in the model test condition. The FEM analyses confirmed the model test results and showed that the improved ground could fail with sliding failure in a certain type of ground conditions such as a floating type improved ground. A simple calculation incorporating the collapse failure pattern gave reasonable estimation of the embankment pressure at ground failure. This paper demonstrates the importance of simulating appropriate failure pattern for evaluating the external stability accurately.     

Internal Stability of Group Column Type Deep Mixing Improved Ground Under Embankment Loading

The Deep Mixing Method (DMM), an in-situ soil stabilization technique using cement and/or lime as a binder, is often applied to improve soft soils. The group column type pattern is extensively applied to stabilize foundations of embankment or lightweight structures. An improved-ground design procedure in Japan assumes two failure patterns related to external and internal stabilities. For the external stability, a collapse failure pattern where the DM columns tilt like dominos could take place instead of a sliding failure pattern. For the internal stability, the DM columns show shear, bending and tensile failure mode, depending not only on the ground and loading conditions but also on the location of each column. However, the current design does not incorporate the effect of these failure modes, but only the shear failure mode. In this study, a series of centrifuge model tests was carried out to investigate the internal stability of group column type improved ground under embankment loading. This paper describes the failure modes of DM columns and a proposed simple calculation that takes into account the bending failure mode.     

受压U肋加劲板局部稳定受力性能数值模拟

为了掌握受压U肋加劲板的局部稳定受力性能,考虑残余应力与初始几何缺陷,建立U肋加劲板局部稳定试验试件的有限元模型,通过考虑不同宽厚比的试验验证该数值模拟方法的正确性;将U肋加劲板及其腹板简化为四边简支板,并通过数值模拟方法验证四边简支板简化模型的正确性。结果表明:采用数值模拟方法计算得到的破坏模态和应力 位移曲线与试验曲线吻合较好,所计入的残余应力和几何缺陷大小是合理的;采用简化的四边简支板模型和试验试件模型计算的应力 位移曲线从开始到峰值吻合较好,在下降段四边简支板模型下降斜率有所增大;在分析受压U肋加劲板受力性能时,可以选用等效四边简支板简化模型分析其局部稳定承载力。     

钉形水泥土双向搅拌桩施工技术

介绍了钉形水泥土双向搅拌桩的特点、成桩机械、施工工艺等;通过工程实例提出了钉形桩施工技术参数、施工技术要点,进行了成桩质量分析和经济对比分析,对于该项新技术的推广应用具有重要意义。     

大面积堆载下水泥土搅拌桩复合地基数值模拟

针对广州龙穴地区某软基处理工程,应用三维有限元计算方法,建立了一个本场地搅拌桩复合地基的数值模型.通过一系列针对现场试验的模拟,将计算结果与实测资料相比较.证明了模型能够较为精确地反映复合地基变形特性.最后,运用所建模型实现了对所研究场地在大面积上覆荷栽下沉降变形的预测,从而检验拟定搅拌桩地基加固方案是否能够满足设计标准,为确定施工方案提供了参考.     

水泥搅拌桩支护条件下的深基坑土方开挖关键施工技术

广州南沙滨海花园五期住宅项目工程的基坑超大、超深,由于地处淤泥质土层,且工期较紧,因此采取基坑支护、土方开挖同步施工方法。详细介绍了在基坑支护出现大位移情况下,应用土方分块、土方抽条、分离式施工、核心筒处基坑后置等关键技术措施,确保了基坑支护结构的安全性和可靠性,使基坑施工得以顺利完竣。     

水泥搅拌桩复合地基设计计算

指出水泥搅拌桩设计计算中应注意的几个问题，同时总结了水泥搅拌桩设计计算的一般步骤，以使工程实践中的水泥搅拌桩的设计计算更为合理。     

水泥搅拌桩-锚杆组合支护结构受力特性及变形性态的研究

水泥搅拌桩 -锚杆组合支护结构是一种新型的组合支护结构 ,本文采用有限元方法进行各种参数研究 ,分析了该组合支护结构的受力特性及变形性态。通过计算结果与实测数据的比较 ,表明本文所得结论对该组合支护结构的应用有一定的指导价值     

微型桩芯搅拌桩破坏模式与承载力设计研究

微型桩芯水泥搅拌桩在江苏沿海沿江地区的地基加固工程中已有应用,并逐步推广。本文阐述了该复合桩的构造特点、复合桩复合地基的工作特性,分析了复合桩在竖向荷载作用下的外圈界面、无芯段桩体水泥土、有芯段桩体水泥土、内圈界面与桩芯混凝土破坏等五种破坏模式,通过工程案例介绍了复合桩的承载力、桩芯优化长度和复合桩复合地基承载力设计方法。