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本文通过阐述永春新颖有限公司厂房桩基工程的不同方案,重点是桩端选择不同的岩土持力层上产生的不同的单桩极限承载力,及其最终的不同桩基成本。通过不同桩基成本的比较,为以后工程地质条件相近的桩基工程施工提供借鉴。 相似文献
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真光中学教学实验楼基础采用人工挖孔桩,经过桩基抽芯检测显示,少数桩桩端持力层为强风化岩层,不符合设计要求。后通过补充勘察,进一步查明场地的工程地质条件。根据勘察报告提供的各岩土层的岩土计算参数,经过桩基计算后发现,桩端持力层为强风化岩层的桩单桩竖向承载力不能满足设计要求,因此对桩端持力层为强风化岩层的桩采用压力灌浆法进行补强加固。桩基加固后经过验算,其承载力可满足设计要求,沉降观测结果显示变形符合规范要求,说明采用压力灌浆法进行桩基补强加固是有效的。 相似文献
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滨海平原地带预制桩检测时效问题研究 总被引:1,自引:0,他引:1
预制桩的载力具有随时间增长的特点。因此,正确确定不同岩土体工程地质条件的预制桩检测时间的就得十分重要。以实例研究了滨海平原地预制桩的检测时效问题。提出了类假岩土体条件下打桩休止时间,为正确测定桩基载力提供了可靠的依据。 相似文献
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桩端承栽力的确定是岩土工程勘察和桩基设计的重要内容.目前,确定砂土中桩端承栽力的方法很多,不同地区(特别是海外工程)要求按照工程所在地区的标准进行勘察和设计,因此探讨不同地区的桩基承栽力计算方法具有重要的工程意义.针对国外某大型桥梁桩基工程实例,对中外不同地区(包括中国、英国、美国、日本)所推荐的砂土中桩端承载力的计算方法进行了比较,着重探讨了非常密实砂土中的桩端承载力取值,以供相关工程人员参考. 相似文献
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岩质陡坡环境下的桩基需考虑桩顶沉降量对桩基承载特性的影响。推导了按桩顶沉降控制的嵌岩桩的控制微分方程,并建立了桩侧岩土体处于弹性阶段时桩顶极限荷载的求解方法。最后以一具体工程为依托,对该桩基按桩顶沉降量控制进行竖向承载力计算。结果表明依托工程的桩基的竖向承载力是满足要求的,研究结果验证了理论公式的可行性。 相似文献
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硬土层条件下PHC桩的可打性 总被引:2,自引:0,他引:2
桩的可打性是桩基工程中考虑的主要课题之一 ,涉及到场地岩土工程条件的分析 ,桩基的设计 ,打桩设备和打桩工艺流程的优化选择等诸多方面。本文依据某工程的现场试桩结果 ,通过对场地岩土工程条件和试验桩施工监测结果的分析 ,探讨了在较厚硬土层条件下预应力高强混凝土管桩(PHC)的可打性 ,分析结果对于相近条件的桩基工程具有借鉴意义 相似文献
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根据高应变法速度时程曲线在桩底的反射情况和力的时程曲线可判断桩底持力层岩土承载性状,并应用曲线拟合法分析承载力,以此进行桩底持力层岩土状况监控,在遇水易软化的风化岩层地质条件下的桩基承载力检测提供借鉴经验。 相似文献
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Feng ZHANG Katsunori OKAWA Makoto KIMURA 《Frontiers of Architecture and Civil Engineering in China》2008,2(3):233-241
In this paper, dynamic behavior of a grouppile foundation with inclined piles in loose sand has been investigated with centrifuge
model tests. The test results are also simulated with elastoplastic dynamic finite element method, in which, not only sectional
force of piles, stress of ground, but also deformation of piles are calculated using a three-dimensional elastoplastic dynamic
finite element analysis (Code name: DGPILE-3D). The numerical analyses are conducted with a full system in which a superstructure,
a pile foundation and surrounding ground are considered together so that interaction between pile foundation and soils can
be properly simulated because the nonlinearities of both the pile and the ground are described with suitable constitutive
models. Different types of piles, vertical pile or inclined pile, are considered in order to verify the different characteristics
of a group pile foundation with inclined piles. The validity of the calculation is verified by the model tests. 相似文献
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ZHANG Feng OKAWA Katsunori KIMURA Makoto 《Frontiers of Structural and Civil Engineering》2008,2(3):233
In this paper, dynamic behavior of a group-pile foundation with inclined piles in loose sand has been investigated with centrifuge model tests. The test results are also simulated with elastoplastic dynamic finite element method, in which, not only sectional force of piles, stress of ground, but also deformation of piles are calculated using a three-dimensional elastoplastic dynamic finite element analysis (Code name: DGPILE-3D). The numerical analyses are conducted with a full system in which a superstructure, a pile foundation and surrounding ground are considered together so that interaction between pile foundation and soils can be properly simulated because the nonlinearities of both the pile and the ground are described with suitable constitutive models. Different types of piles, vertical pile or inclined pile, are considered in order to verify the different characteristics of a group pile foundation with inclined piles. The validity of the calculation is verified by the model tests. 相似文献
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《Soils and Foundations》2007,47(5):961-972
This paper describes a foundation design method in which the ground is improved around the heads of pile foundations in soft ground or loose sandy ground and its practical effectiveness. The shear strength increased due to ground improvement is reflected in the horizontal resistance of piles. In this design method, the influence range of the horizontal resistance of piles and the necessary range of ground improvement are determined by taking account of three-dimensional domain formed with the gradient of the surface of passive failure. The horizontal subgrade reaction of piles is evaluated by converting the shear strength of improved ground to the modulus of deformation. In this study, the validity of design method for the pile foundation with ground improvement was confirmed through an in-situ horizontal loading test. The dynamic behavior of pile foundation constructed in improved ground was also investigated through a series of centrifuge model tests and numerical analyses. The influence of the difference in strength between the original and improved grounds on piles during an earthquake was also confirmed based on the numerical analyses. The cost performance of the proposed method was discussed by comparing with the case without ground improvement. 相似文献
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刚-柔性桩复合地基是近年才发展起来的一种新型地基处理方式,其理论的发展明显地落后于工程实践,尚未形成比较完善的设计理论和计算方法。应用条形基础下刚-柔性桩复合地基实用简化的设计方法对工程实例进行优化设计,结果表明,刚-柔性桩复合地基能合理发挥刚性桩、柔性桩以及土体的力学性能,有显著的经济效益。 相似文献
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柔性基础下粉喷桩复合地基的承载力计算 总被引:4,自引:0,他引:4
通过现场实测及有限元计算,讨论了采用粉喷桩处理饱和黄土与淤泥质土所形成的复合地基,在柔性基础作用下,基础刚度及复合地基中的桩体对复合地基承载力的影响。结果表明:减小基础刚度有利于桩间土体承载力的发挥;桩体对饱和黄土承载力的影响程度大于对淤泥质土体承载力的影响程度。最后依据实测及有限元分析结果,在原有刚性基础下粉喷桩复合地基承载力计算公式的基础上,增加了基础刚度影响系数与桩间土体承载力提高系数,并给出了各影响系数的建议取值范围,使其适用于柔性基础下复合地基的承载力计算。 相似文献
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夯实水泥土楔形桩复合地基承载特性试验研究 总被引:5,自引:0,他引:5
针对软土地基中的夯实水泥土桩复合地基,分别进行1组等截面桩和3组不同楔角楔形桩的9桩复合地基对比试验,研究4组复合地基在相同条件下的平均沉降和平均桩–土应力比随荷载变化的规律以及荷载传递规律。试验结果表明:夯实水泥土楔形桩能有效地调节桩–土沉降差和地基沉降,提高地基承载力;增大楔形桩的楔角能使桩体较早地发挥其承载性能,夯实水泥土楔形桩复合地基的平均桩–土应力比较夯实水泥土等截面桩复合地基的大;随侧壁倾角的增大,夯实水泥土楔形桩桩身轴力的衰减速率不断增大,随荷载传递深度不断减小,楔形桩的工作性状远优于等截面,且侧壁倾角越大,桩体的性状能得到较好地发挥。 相似文献
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《Soils and Foundations》2014,54(2):126-140
Piled raft foundation has been widely recognized as a rational and economical foundation system with the combined effects of raft and piles. However, the behavior of laterally loaded piled raft foundation has not been well understood due to the complicated interaction of raft–ground–piles. A series of static horizontal loading tests were carried out on three types of foundation models, i.e., piled raft, pile group and raft alone models, on sand using a geotechnical centrifuge. In this paper, the influences of relatively large moment load and rotation on the overall performance of laterally loaded piled raft foundation were examined. From the centrifuge model tests, it is found that the vertical displacement due to horizontal loads is different between piled raft and pile group foundation, and this vertical displacement has significant influences on the performance of laterally loaded piled raft foundation. The horizontal resistance of the pile part in the piled raft foundation is higher than those observed in the pile group foundation due to raft base contact pressure. The vertical displacement of the foundation due to the horizontal loads affects the vertical resistances of piles, which results in the different mobilization of moment resistances between the piled raft and pile group foundations. 相似文献
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临近基坑开挖引起复合地基CFG桩变形和内力改变,现有理论缺乏对该问题的研究。通过开展离心模型试验,对临近基坑开挖条件下,复合地基变形、CFG桩内力和变形、土压力等分布和变化规律进行深入分析。结果表明:开挖引起CFG桩弯矩增大,近基坑桩增幅明显|开挖引起桩土不同步沉降,导致CFG桩上刺入褥垫层,桩受到褥垫层的“嵌固拉结”作用,同时远基坑桩、褥垫层、加载气囊一起提供了“摩擦拉结”作用,从而在近基坑桩上出现负弯矩|而远基坑处不均匀沉降小,“嵌固拉结”作用小,且“摩擦拉结”作用是利于正弯矩产生,桩上未出现负弯矩|开挖引起支护背后土压力分为增长区和减小区两部分,在上部土体中,土体卸荷,土压力减小,而下部土体受支护挤压,土压力有所增大|开挖引起地表沉降呈指数形式,临近基坑地表沉降最大,在显著变形区域内,支护水平位移基本呈直线形式,各阶段最大水平位移均出现在支护顶端|开挖引起的CFG桩水平变形大小和范围随距基坑边距离的增大而减小。 相似文献