| 桩端后注浆对大直径灌注桩影响的现场对比试验研究 |
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| 引用本文： | 李永辉,朱 翔,周同和.桩端后注浆对大直径灌注桩影响的现场对比试验研究[J].岩土力学,2016,37(Z2):388-396. |
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| 作者姓名： | 李永辉 朱 翔 周同和 |
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| 作者单位： | 1. 郑州大学 土木工程学院，河南 郑州 450001；2. 郑州大学综合设计研究院有限公司，河南 郑州 450002； 3. 河南五建建设集团有限公司，河南 郑州 450000 |
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| 基金项目： | 国家自然科学基金（No. 51508522）；郑州市重大科技专项课题（No. 113PSHKS439）。 |
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| 摘 要： | 基于郑州三环快速路工程开展的6个场地19根大直径灌注桩现场足尺试验，通过对比分析后注浆桩与未注浆桩实测结果，研究桩端后注浆对大直径灌注桩承载变形性状、荷载传递规律、桩端承载特性及桩侧摩阻力发挥性状的影响。结果表明，桩端后注浆条件下大直径灌注桩承载变形性能明显提高，且提高幅度受注浆龄期影响较为显著；在黄河中下游以中密～密实粉土、粉细砂及可塑～硬塑粉质黏土为主要冲积地层中桩长40 m左右的大直径灌注桩表现为摩擦型桩，但相比于未注浆桩，桩端后注浆桩传递至桩身下部及桩端的荷载更小；桩端后注浆在桩端下形成水泥沉渣坚硬固结体，有效地处理了桩端沉渣问题，且通过渗透劈裂作用，形成深度可达1 m的网状分布的水泥胶结体，加之对桩端土层的压密效应，显著提高了桩端支承性能与承载刚度；桩端后注浆显著提高大直径灌注桩桩侧极限摩阻力发挥水平，并降低了桩侧极限摩阻力对应的桩土相对位移，使得大直径灌注桩在较小的沉降下表现出较高的承载能力。
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| 关 键 词： | 大直径灌注桩 桩端后注浆 现场试验 承载特性 桩土相对位移 |
| 收稿时间： | 2016-07-26 |
Experimental study of effects of pile tip post grouting on bearing characteristics of large-diameter bored pile |
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| LI Yong-hui,ZHU Xiang,ZHOU Tong-he.Experimental study of effects of pile tip post grouting on bearing characteristics of large-diameter bored pile[J].Rock and Soil Mechanics,2016,37(Z2):388-396. |
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| Authors: | LI Yong-hui ZHU Xiang ZHOU Tong-he |
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| Institution: | 1. College of Civil Engineering, Zhengzhou University, Zhengzhou, Henan 450001, China; 2. Comprehensive Design and Research Institute Co., Ltd., Zhengzhou University, Zhengzhou, Henan 450002, China; 3. Henan Wujian Construction Group Co., Ltd., Zhengzhou, Henan 450000, China |
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| Abstract: | Based on 19 field pile load tests in 6 sites of Zhengzhou third ring rapid road engineering, pile bearing and deformation characteristics, load transfer laws, pile tip bearing capacities and pile friction behaviors of the pile tip grouted large-diameter bored pile are studied by comparing the field test results of the post grouted pile and pile without grouting. The results show that the bearing capacity of large-diameter bored pile is significantly improved under the condition of pile tip grouting. The influence of the capacity increasing amplitude is significantly influence by the grouting age. In alluvial deposits with soils mainly of medium dense to dense silt, fine sand and plastic to hard plastic silty clay in the middle and lower reaches of the Yellow River, the large-diameter bored pile with a length of about 40 m shows characteristics of friction pile. However, the loads that are transferred to the lower part of the pile shaft and pile bottom of the pile tip grouted pile are smaller. Hard cement sediment concretion body be form under the pile tip by the pile tip post grouting, which is effectively deal with the problem of the sediment under the pile tip. Moreover, cement bond body with mesh distribution be also form in the soil with a depth of nearly 1 m under the pile tip through the fracturing and penetration effect of the post grouting. Coupled with the compaction effect of pile tip soil by the high pressure grouting, the bearing performances of the pile tip and the bearing stiffness are significantly improved; pile side friction ultimate resistances of the large-diameter bored pile is significantly improved by the pile tip post grouting. However, the pile-soil relative displacements which are correspond to the pile ultimate side friction resistances are reduced by the grouting. These are why the post grouted large-diameter bored pile shows higher bearing capacity in the small settlement. |
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| Keywords: | large-diameter bored pile pile tip post grouting field test bearing characteristic pile-soil shear displacement |
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