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JOURNAL OF ZHEJIANG UNIVERSITY (ENGINEERING SCIENCE)
    
Vertical bearing capacity of large-diameter bored pile
LIU Nian-wu1,2, GONG Xiao-nan1,2, YU Feng3
1.Research Center of Coastal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China; 2. MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Zhejiang University, Hangzhou 310058, China;3. School of Civil Engineering and Architecture, Zhejiang Sci-Tech University, Hangzhou 310018, China
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Abstract  

The self-balancing test was conducted on two 2.2 m diameter drilled piles in order to analyze the bearing capacity of large diameter bored piles. The test results were compared with in-situ test results. Results show that the change of load-displacement of pile with post-grouting is slower than pile without post-grouting. The end resistance reached the limit state when pile tip displacements approached 20 mm (1% D, D is the pile diameter). The side resistance increased firstly and maintained a stable trend with the increase of pile-soil relative displacement. The critical displacement was 1.5-3.0 mm. Post-grouting can improve the side resistance over a certain depth from the pile tip, and the improvement in round gravel mixed pebble bed is 18 percent. Resistive loads up and down the side of the load cell is different and transformation coefficient is 0.92 and 0.91, respectively. Side resistance and undrained vane-shear strength has a linear relationship and has a better goodness of fit. The ultimate side resistance of round gravel mixed can be estimated by dynamic sounding (63.5 kg) hits.



Published: 01 April 2015
CLC:  TU 473  
Cite this article:

LIU Nian-wu, GONG Xiao-nan, YU Feng. Vertical bearing capacity of large-diameter bored pile. JOURNAL OF ZHEJIANG UNIVERSITY (ENGINEERING SCIENCE), 2015, 49(4): 763-768.

URL:

http://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2015.04.022     OR     http://www.zjujournals.com/eng/Y2015/V49/I4/763


大直径钻孔灌注桩的竖向承载性能

为了分析大直径钻孔灌注桩的承载性能,对2根直径分别为2.2 m的钻孔灌注桩开展自平衡试验,将试验结果与原位测试结果进行对比分析.通过对测试结果的分析发现,注浆后荷载箱的向上及向下荷载-位移曲线的变化更加缓慢,当桩端位移为20 mm(1%D,其中D为桩径)左右时,端阻达到极限状态,未注浆桩和注浆桩的极限端阻分别为2 834、3 561 kPa.桩身侧阻随着桩土相对位移的增大呈先增大后保持稳定的趋势,淤泥质粉土层、黏土夹粉砂层、圆砾混卵石层的侧阻在桩土相对位移为1.5~3.0 mm时达到稳定.注浆能够提高桩端以上一定深度的桩身侧阻,圆砾混卵石层中侧阻的提高幅度约为18%.荷载箱上下的侧阻随位移的变化模式不同,未注浆桩和注浆桩的转换系数的取值分别为0.92、0.91.桩的极限侧阻与不排水剪切强度呈线性关系,且桩的极限侧阻与不排水剪切强度具有较好的拟合度.圆砾混卵石层中极限侧阻与动力触探(63.5 kg)击数有一定的相关性.

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