共查询到19条相似文献，搜索用时 156 毫秒
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研究目的:研究混凝土芯水泥土搅拌桩在路堤荷载下的荷载传递规律和变形控制机理。创新要点:评价路堤荷载下混凝土芯水泥土搅拌桩的地基处理效果,测量混凝土芯的竖向应力变化规律和复合地基桩土荷载分担特点,并分析填土过程中混凝土芯水泥土搅拌桩复合地基的固结规律。研究方法:通过埋设沉降板、分层沉降管、测斜管、土压力盒、孔隙水压力计以及钢筋应力计,在路堤填筑过程中对混凝土芯水泥土搅拌桩复合地基进行了长期现场试验。重要结论:1.混凝土芯水泥土搅拌桩复合地基的总沉降、工后沉降以及深层水平位移控制效果均较好,优于普通水泥土搅拌桩复合地基;2.混凝土芯水泥土搅拌桩复合地基的桩土应力比以及荷载分担比均大于普通水泥土搅拌桩复合地基,能有效减小土体表面的荷载量,对于控制沉降有一定的效果。3.在路堤这种柔性荷载作用下,混凝土芯水泥土搅拌桩上部会出现一定的负摩擦阻力,存在一个"中性点"。4.混凝土芯水泥土搅拌桩复合地基的固结速率较快,能有效控制由于主固结引起的长期沉降。 相似文献
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郑军锋 《福建工程学院学报》2019,(4):307-313
对新建兴泉铁路黄塘车站挤密螺纹桩复合地基的桩、土沉降及应力进行监测,分析了路堤荷载下桩、土沉降及差异沉降变化规律,桩土应力比与差异沉降关系。结果表明:桩、土沉降及差异沉降均随路堤填土高度的增加而呈线性增大;桩顶和桩间土应力随路堤填土高度的增加均不断增大,且桩顶应力大于桩间土应力;桩土应力比随着桩土差异沉降的增加先增加后减小,最终趋于稳定。结合修正的Terzaghi土拱理论提出了简化桩土应力比随桩土差异沉降变化曲线。现场试验分析结果有助于完善挤密螺纹桩复合地基设计理论,为工程实践提供一定的参考。 相似文献
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加芯搅拌桩复合地基设计施工要点 总被引：1，自引：0，他引：1
加芯搅拌桩具有高承载力、低沉降、造价低、保护环境、应用范围广等特点。2001年11月作者在昆明吴井广发苑二期工程中设计加芯搅拌桩复合地基，是云南省建设工程中首次应用加芯搅拌桩技术，之后发起组建云南《加芯搅拌桩复合地基研究》科研项目组，任科研负责人、项目组组长。3年来云南省应用加芯搅拌桩地基处理建房约15万平米，本文依据作者加芯搅拌桩存在三种破坏状态、具有设计可调性论述，总结工程实践经验，结合专利《加混凝土芯水泥土搅拌桩》(ZL02275785．6)撰写，以满足教学、科学研究和专利实施工程应用需要。 相似文献
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本以水泥搅拌桩复合地基为例，应用有限元软件Plaxis对轴对称荷载作用下复合地基沉降计算模型进行计算分析，研究了沉降发展规律以及加固深度，土体渗透系数对下卧层固结沉降的影响等问题，得出了一些有益的结论。 相似文献
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通过对水泥搅拌桩固结机理的分析,研究水泥搅拌桩提高软土复合地基承载力的技术措施。结合武夷山市变电站工程实例,水泥搅拌桩设计直径550 mm,桩身设计强度等级1.5 kpa,采用搅拌喷浆施工方法形成水泥桩,使用慢速维持荷载法对加固效果进行复合地基荷载试验,最大试验荷载加至180 KN,绘制了P-S曲线。结果显示复合地基承载力特征值均为90 kpa,表明水泥搅拌桩能够满足软土地基加固要求。 相似文献
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结合珠江三角洲地区某水闸软土地基的处理,介绍了水泥土搅拌桩在处理软土地基中的设计和施工.该工程地基水泥土搅拌桩处理后,经检验,最大沉降量与最大沉降量差均较小,工程运行情况良好. 相似文献
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本文对水泥土的固结机理和水泥土挤密桩的加固原理进行了理论分析.水泥土挤密桩加固是基于复合地基原理的一种加固方法.力口固机理是以桩间土的侧向挤密和桩身置换作用为本,从理论上讲能够起到加固路基的作用. 相似文献
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CFG桩与夯实水泥土桩组合型复合地基 总被引：1，自引：0，他引：1
根据CFG桩与夯实水泥土桩组合型复合地基的承载机理和特性，提出了将两者结合应用的组合型复合地基，并结合实际地基处理工程，通过现场试验，对复合地基的加固机理和在荷载作用下桩土的受力特性进行分析，证明它具有加固作用明显、变形小、稳定快的特点． 相似文献
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Wan-huan Zhou Ren-peng Chen Lin-shuang Zhao Zheng-zhong Xu Yun-min Chen 《浙江大学学报(A卷英文版)》2012,13(11):888-894
In this paper, a semi-analytical method for the analysis of pile-supported embankments is proposed. The mathematic model describes the cooperative behavior of pile, pile cap, foundation soil, and embankment fills. Based on Terzaghi??s 1D consolidation theory of saturated soil, the consolidation of foundation soil is calculated. The embankments with two different types of piles: floating piles and end-bearing piles are investigated and discussed. The results of axial force and skin friction distributions along the pile and the settlements of pile-supported embankments are presented. It is found that it takes a longer time for soil consolidation in the embankment with floating piles, compared with the case using end-bearing piles. The differential settlement between the pile and surrounding soil at the pile top is larger for the embankment with end-bearing piles, compared with the case of floating piles. 相似文献
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Bearing capacity and load transfer mechanism of a static drill rooted nodular pile in soft soil areas 总被引：2，自引：0，他引：2
The static drill rooted nodular pile is a new type of pile foundation consisting of precast nodular pile and the surrounding cemented soil. This composite pile has a relatively high bearing capacity and the mud pollution will be largely reduced during the construction process by using this type of pile. In order to investigate the bearing capacity and load transfer mechanism of this pile, a group of experiments were conducted to provide a comparison between this new pile and the bored pile. The axial force ofa precast nodular pile was also measured by the strain gauges installed on the pile to analyze the distribution of the axial force of the nodular pile and the skin friction supported by the surrounding soil, then 3D models were built by using the ABAQUS finite element program to investigate the load transfer mechanism of this composite pile in detail. By combining the results of field tests and the finite element method, the outcome showed that the bearing capacity of a static drill rooted nodular pile is higher than the bored pile, and that this composite pile will form a double stress dispersion system which will not only confirm the strength of the pile, but also make the skin friction to be fully mobilized. The settlement of this composite pile is mainly controlled by the precast nodular pile; meanwhile, the nodular pile and the surrounding cemented soil can be considered as deformation compatibility during the loading process. The nodes on the nodular pile play an important role during the load transfer process, the shear strength of the interface between the cemented soil and the soil of the static drill rooted pile is larger than that of the bored pile. 相似文献
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In the eastern coastal region of China, many operating highways built over soft ground are vulnerable to severe post-construction settlement. In this study, a technique using jet grouted piles is developed to mitigate post-construction settlement. The piles are installed by drilling boreholes throughout the embankment. The principal stages of the construction process are described, and two field tests in China, on the Lianyan and Linhai highways, are presented. The results revealed that ground heaves of up to 219 mm and 337 mm induced during a short construction period were able to mitigate the settlement of the embankment. The average settling rate was significantly reduced from 60 mm/y to 9 mm/y on the Lianyan highway. Lateral ground displacement on the Linhai highway increased with time during construction, but after construction showed a slight reduction associated with the dissipation of excess pore water pressure. An analytical method was adopted to describe the ground heave due to the jet grouted piles. The ground heave increased with grout pump pressure, but decreased as the embankment load and distance from the pile center increased. 相似文献
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As a new technique in ground improvement, geosynthetic-encased columns (GECs) have promising applications in soft soil foundation. By assuming yielding occurs in the columns while the surrounding soil and the geosynthetic remain elastic, an elastoplastic analytical procedure for foundations improved by GECs is proposed. The radial stresses that the geosynthetic provides and the elastoplastic deformations of the foundation resting on a rigid base are derived. A comparison with finite element analysis shows that the proposed method is effective and can provide a reasonable prediction of a GEC??s deformation. Subsequent parametric analysis indicates that higher geosynthetic stiffness leads to better performance of the composite foundation. The optimum length of encasement is related to the load acting on the foundation and the permissible vertical and radial displacements of the column. Moreover, as the dilation angle of the column increases, the settlement decreases, especially under high loading. The influence of the encasement is more significant in soils with smaller elastic modulus. 相似文献
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Bearing Capacity of Mixed Pile with Stiffness Core 总被引：3，自引：0，他引：3
To study load transfer mechanism and bearing capacity of a mixed pile with stiffness core (MPSC), which is formed by inserting a precast reinforced concrete pile (PRCP), in-situ tests involving MPSCs with different lengths, diameters, water cement ratios and PRCPs, cement mixed piles, and drilling hole piles, were carried out. Limit bearing capacities, load-settlement curves and stress distribution of MPSCs and mixed piles were obtained. The load transfer between cement soil and PRCP was analyzed by finite element method (FEM). Test results and FEM analysis show that an MPSC has fully utilized the big friction from a cement mixed pile and the high compressive strength from a PRCP which transfers outer top load into the inner cement soil, and that inserting a PRCP into a mixed pile changes the stress distribution of a mixed pile and improves frictional resistance between a mixed pile and soil. The length and the section area on PRCP of an MPSC both have an optimum value. Adopting MPSC is effective in improving the bearing capacity of soft soil ground. 相似文献
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The consolidation behavior of mixed in place cement- and lime/cement-mixed column was studied. Consolidation of the composite
foundation was modeled as a three-dimensional axi-symmetric problem. The authors used the finite difference method to obtain
the pore pressure variation with time at any location below the surface. A computer program developed by the authors was used
to draw some interesting conclusions about the consolidation behaviors of cement- and lime/cement-mixed pile foundation. Finally,
a combined model including the permeability coefficients of cement-mixed piles and soil, was studied and its feasibility was
evaluated.
Project supported by National Natural Science Foundation of China (No. 59908012) and Education Ministry of China 相似文献
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张俊斌 《福建工程学院学报》2003,1(3):49-51
通过某小区三幢住宅楼9根小截面静压预制桩静载试验成果分析，表明以侧阻力为主的摩擦型预制桩Q—s曲线呈双曲线的特征。采用斜率-倒数法对该小区静压预制桩单桩极限承载力进行预测，并将预测结果与理论计算结果进行对比，分析结果表明《建筑桩基技术规范》JGJ94—94中有关预制桩承载力指标的取值偏低，其指标不适合小截面静压预制桩。结合桩基施工终压力和每延米压桩耗能的对比分析，表明桩的竖向极限承载力与终压力存在一定的比例关系，但与压桩耗能不存在比例关系。 相似文献