首页|不均匀卵石持力层桩端后注浆效果试验研究

不均匀卵石持力层桩端后注浆效果试验研究

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我国东南沿海尤其是温州地区广泛存在上覆深厚软土下覆不均匀卵石的地层.该区域的钻孔灌注桩常采用后注浆技术改善其承载性能.为了评价后注浆技术对这类地层中灌注桩承载力改善效果,开展了相应的模型试验,对比了不同注浆量对桩承载力的影响程度;并结合扫描电镜(scanning electron microscope,简称SEM)试验分析了浆液分布特点,探讨了浆液在卵石层中的扩散范围,研究了浆液扩散范围与桩承载力之间的关系.结果表明:浆液能够有效地填充桩端卵石层,注浆量的增加使得填充范围扩大,填充范围为3～4倍桩径时,桩的承载力改善最显著.在不均匀卵石持力层中存在一个最优注浆量,最优归一化注浆量约为2.8,若超过该最优注浆量归一化值,桩的承载力不再显著提高.单桩模型试验确定的最优注浆量与刘金砺公式[1]的预测结果接近.扫描电镜技术有助于评价桩的后注浆技术在上覆深厚软土下覆不均匀卵石的土层中的效果.
Experimental study of post-grouting effect of piles installed in inhomogeneous pebble bearing layer
The southeast coast of China,particularly in Wenzhou,is characterized by soil strata comprising a thick layer of soft soil overlying an uneven pebble layer.In this region,post-grouting technique is frequently employed to enhance the bearing performance of bored piles.To assess the effectiveness of post-grouted piles in such strata,several model tests were carried out to analyze the impact of varying grouting volume on the bearing capacity of the piles.Subsequently,scanning electron microscope(SEM)tests were used to explore the distribution ranges of the grout in the pebble layer.Furthermore,the relationship between the diffusion range and the bearing capacity of piles was investigated.The results show that the grout effectively permeates the pebble around piles tip,and increasing the grouting volume expands the permeated range.The most significant improvement in pile bearing capacity occurs when the range is 3-4 times the pile diameter.An optimal grout volume level is identified,with the normalized value of the grout volume being approximately 2.8 for the model piles.The bearing capacity of the pile is no longer significantly increased once the normalized value of the grout volume is exceeded.Notably,the optimal grout volume closely aligns with the predicted result of Liu Jinli's formula[1].The utilization of scanning electron microscopy proved instrumental in evaluating the effect of post-grouting in a soil layer characterized by a thick layer of soft soil overlying an inhomogeneous pebble layer.

pebble bearing layerpost-grouting at pile tipgrouting volumestatic load testscanning electron microscope(SEM)microscopic evaluation

王军、金天、秦伟、张峰、蔡瑛

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温州大学建筑工程学院,浙江温州 325035

浙江省软弱土地基与海涂围垦工程技术重点实验室,浙江温州 325035

滨海软土地基防灾减灾技术浙江省工程研究中心,浙江温州 325035

浙江省超软土工程技术与智能化监测国际科技合作基地,浙江温州 325035

温州市交通压电工程技术重点实验室,浙江温州 325035

温州市建筑节能减排与防灾减灾工程技术研究中心,浙江温州 325035

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卵石持力层 桩端后注浆 注浆量 静载试验 电镜扫描 细观评价

国家自然科学基金青年项目温州市科技局项目温州市科技局项目浙江省教育厅专培项目温州大学科研创新项目

52008318X2023102S20210004Y202351959JWXC2023229

2024

10.16285/j.rsm.2023.0671

岩土力学
中国科学院武汉岩土力学研究所

岩土力学

CSTPCD北大核心
影响因子：1.614
ISSN：1000-7598
年,卷(期)：2024.45(5)
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