共查询到20条相似文献，搜索用时 15 毫秒
1.
采用理论分析的方法,首先基于半无限土体中改进的球孔扩张理论,求解新桩沉桩挤土效应引起的土体位移场。然后将其作为已知条件施加于邻近既有桩,分析既有桩变形和内力变化规律,探讨既有桩桩端约束条件、桩身刚度及土体模量对既有桩响应的影响;同时结合数值分析,对本文理论方法进行验证。最后分析了新旧桩之间距离和新桩半径对挤土效应引起的既有桩变形和内力的影响。结果表明：桩端约束形式仅影响桩端附近桩身变形;随着新旧桩之间距离的增加,既有桩变形和内力显著减小;随着桩径的增加,既有桩变形和内力均逐渐增大。最后提出采用远离既有桩和采用长细桩的措施来降低新桩施工对既有桩的影响。 相似文献
2.
筒桩与普通沉管灌注桩施工挤土效应比较 总被引：4，自引：0，他引：4
应用圆孔扩张理论 ,分析了筒桩施工挤土效应 ,并通过比较 ,得出筒桩施工挤土效应远远小于普通沉管灌注桩或预制实心桩 ;筒桩可内外承担摩阻力 ,承载力高 ,挤土效应小 ,是一种比较理想和值得推广的桩型。 相似文献
3.
基坑开挖后坑底土体回弹,将会带动坑内基桩回弹,并在桩侧产生侧摩阻力。为了分析基坑开挖条件下单桩及群桩的受力变形特性,采用三维有限元方法对单桩及群桩在基坑开挖条件下的回弹位移进行了分析。分析结果表明,基桩在基坑开挖条件下的回弹位移分为桩侧土体回弹而引起的基桩回弹和下卧层回弹导致的基桩回弹两部分。由于群桩外侧桩的遮帘效应,中心桩的回弹位移小于外侧桩,中心桩桩侧摩阻力的发挥量也小于外侧桩。随下卧层相对刚度Eb/Ec变大,5×5群桩回弹位移相对减小量Wr变大,且Wr的变化与桩位置有关。3种不同构形群桩的对比分析结果表明:群桩桩数越多,遮帘效应越明显;Wr受桩数的影响大于受桩间距的影响。 相似文献
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The vibratory driving technique is used for driving piles, sheet piles, tubes and rods into the ground by imparting to the element a longitudinal periodic motion. The small amplitude vibrations induced by the equipment reduce the ground resistance which allows penetration under the action of a relatively small axial force. The technique offers an alternative to impact driving due to lower installation costs and reduced environmental disturbance (noise, vibration, etc.) especially in sensitive environments, such as industrial and urban sites or offshore wind farm sites. The vibratory technique is also preferred when the maximum stress levels imparted to the driven element are of concern. Despite the advantages of the vibratory driving technique, its application remains however mainly driven by pragmatic aspects. Within that context, the access to experience databases and full-scale field test results is of valuable interest. The aim of this paper is to review the Hypervib1 model developed by (Holeyman 1993) for assessing the vibratory drivability of piles and sheet piles, based on the analysis of such experimental results. New findings and developments brought to the model are discussed. Conclusions in terms of reliability of the method are finally drawn. 相似文献
6.
桩端沉降测量和试桩资料的分析结果表明,桩在传递上部荷载与地基土之间产生的应力应变过程,表现为桩的弹性杆件和地基土的弹—塑性变形特征。从而对受荷桩,尤其是长柱和超长桩的应力应变特征有了更切合实际的认识。 相似文献
7.
Yoon Seok Choi Jintae Lee Monica Prezzi Rodrigo Salgado 《Geotechnical and Geological Engineering》2017,35(4):1587-1604
Although the loads applied on piles are usually a combination of both vertical and lateral loads, very limited experimental research has been done on the response of pile groups subjected to combined loads. Due to pile–soil–pile interaction in pile groups, the response of a pile group may differ substantially from that of a single pile. This difference depends on soil state and pile spacing. This paper presents results of experiments designed to investigate pile interaction effects on the response of pile groups subjected to both axial and lateral loads. The experiments were load tests performed on model pile groups (2 × 2 pile groups) in calibration chamber sand samples. The model piles were driven into the sand samples prepared with different relative densities using a sand pluviator. The combined load tests were performed on the model pile groups subjected to different axial load levels, i.e., 0 (pure lateral loading), 25, 50, and 75% of the ultimate axial load capacity of the pile groups, defined as the load corresponding to a settlement of 10% of the model pile diameter. The combined load test results showed that the bending moment and lateral deflection at the head of the piles increased substantially for tests performed in the presence of axial loads, suggesting that the presence of axial loads on groups of piles driven in sand is detrimental to their lateral capacity. 相似文献
8.
抗滑桩与桥梁桩和普通侧向受荷桩结构设计的区别在于,抗滑桩容许"大位移"和"超配筋"。荷载结构计算法采用10mm为位移容许值,导致抗滑桩工程设计中不能充分发挥"大位移"的抗滑性能。本文结合钢筋混凝土受弯构件力学原理,引入抗滑桩裂缝控制准则,在荷载结构计算法的基础上,用裂纹控制准则替代桩顶水平位移容许值进行抗滑桩设计验算,可最大限度地挖掘抗滑桩的抗滑潜力;推导基于K法的抗滑桩设计验算方法的计算公式,阐述裂纹控制荷载结构法的原理、计算和设计流程;以十堰天水国家高速公路K593+850-K594+070滑坡治理工程为案列,分析了抗滑桩桩顶的水平位移组成和影响因素,并比较了传统设计法与本文阐述方法的优缺点。结果表明:桩顶水平位移主要由锚固段岩土体变形引起,位移由岩土体刚度决定,与桩体设计参数无关,优化桩体设计参数仅能限制由桩身弹塑性变形引起的桩顶水平位移。 相似文献
9.
本文介绍在厦门新市区新近海相沉积土层上,进行静压沉桩的现场试验资料、分析了静压沉桩的力学机理,试验成果的应用及与其他相应桩型的经济比较。认为,在工程地质情况相类似的多、中高层民用建筑中采用,工程质量可靠,并可获得较好的经济效益。 相似文献
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11.
Satyendra Mittal B. Ganjoo Sunny Shekhar 《Geotechnical and Geological Engineering》2010,28(5):717-725
The screw anchor piles are installed in ground by screwing which is done with the help of torque motors. In this paper, the
lateral load capacity of screw anchor piles is examined through an experimental investigation carried on model piles embedded
in dry sand. The tests were carried on screw anchor piles with different number of helices provided in continuation. Lateral
loads were applied at different height above the soil surface. The embedment length of screw anchor piles was also varied
to study the behaviour of screw anchor piles under lateral loads. Some tests were conducted on plain shaft pile to compare
the lateral load capacity of screw anchor piles with that of plain shaft piles. An empirical equation for computation of lateral
loads has been developed considering lateral resistance, bearing resistance, uplift resistance and lateral resistance offered
by soil in pile on the basis of experimental results. A theoretical model for predicting lateral load capacity of screw anchor
piles in dry sand, consistent with the experimental findings has been developed in this study. 相似文献
12.
This paper discusses the difference between reflections of waves in frictional pile and end-bearing pile, based on the solutions of wave equations. The influences of various defects on wave are analyzed. These make theoretical basis for wave analysis of nondestructive inspection of piles. 相似文献
13.
介绍了超声波透射法检测桩身完整性的基本原理,分析了超声波声学参数与混凝土质量的芜景。通过2根模型桩实测数据判断结果与模型桩缺陷设计进行对比分析,表明超声波透射法能够准确的判断人工挖孔桩的缺陷部位、大小及严重程度等信息,说明超声波透射法是一种行之有效的桩身完整性无损检测方法。 相似文献
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15.
长短桩复合地基设计计算的探讨 总被引：9，自引：3，他引：9
通过对长短桩复合地基承载力计算的不同公式进行对比分析 ,提出比较适宜的设计方法 ,并提出其沉降计算公式和加固效果检测方式 ,并将长短桩复合地基理论灵活应用于补桩设计 相似文献
16.
高层建筑桩基础沉降计算 总被引：1，自引：0，他引：1
该文针对建筑桩基础，根据剪切位移法求桩受力时桩间土各点的变形，用文克尔模型求桩间土对基础的反力，对杨敏的高层建筑桩箱(筏)基础沉降计算公式进行修正。 相似文献
17.
文章叙述了探地雷达对桩基探测的一系列实验工作，通过探地雷达三个参数的匹配对比，研究适合在上海地区应用探地雷达探测桩的一些技术措施和方法。 相似文献
18.
通过工程实例,介绍CFG桩在大型油罐地基局部处理中,既有效提高软弱地基强度,又最大限度保持不同地基变形协调一致的处理方法.针对油罐体型的特殊性,采用了沿油罐圆心环形布桩,并且根据不同地段地基土性质的纵横向差异采用不等距布桩的方案.复合地基处理效果理想,达到了预期的设计目的,为类似工程的地基处理提供了一种新的设计理念,供类似工程参考. 相似文献
19.
抗拔桩变形分析与有效桩长预测 总被引：1，自引：0，他引：1
以抗拔桩变形的理论分析为基础,选择双曲线荷载传递函数对桩的极限侧阻力进行合理取值,通过迭代法得到桩身受力情况,由此预测抗拔桩的＂有效桩长＂。结合工程实例进行了计算验证,证明该方法具有实用价值和推广意义。 相似文献
20.
通过对上海救捞局福州救助站码头迁建工程水上施工大口径砂桩的实践,阐述了使用砂桩改善软弱粘性土地基的施工工艺,总结水上施工大口径砂桩的工程质量控制,以及处理方法。 相似文献