| 考虑基坑卸载影响的改进弹性抗力法及其应用 |
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| 引用本文： | 应宏伟,聂文峰,郭雷,杨永文.考虑基坑卸载影响的改进弹性抗力法及其应用[J].岩土力学,2011,32(Z1):129-133. |
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| 作者姓名： | 应宏伟 聂文峰 郭雷 杨永文 |
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| 作者单位： | 浙江大学岩土工程研究所;浙江大学软弱土与环境土工教育部重点实验室;华润置地(苏州)有限公司 |
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| 基金项目： | “十一五”国家科技支撑项目资助(No.2008BAJ06B01);浙江省重点创新团队支持计划资助(No.2009R50050) |
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| 摘 要： | 弹性抗力法是目前实际工程中基坑支护结构变形内力计算的一种主要方法,该方法借鉴的是计算水平荷载作用下竖直放置弹性桩的地基反力系数法,但没有考虑开挖卸载对土抗力系数和坑内土体的变形影响,因而导致变形计算值通常小于实测值。首先在开挖面施加反向自重应力模拟基坑的开挖卸荷,利用Mindlin解得到坑内土体的卸荷应力分布;在前人的实验研究基础上,推导了不同卸荷比下考虑卸荷影响的土体水平抗力系数;将支护结构的变形分解为开挖瞬时的卸载作用和基坑内外水土压力差作用2个阶段,考虑卸载应力路径对坑内土体水平抗力系数以及开挖瞬时变形的影响,对传统的弹性抗力法进行了改进,最后将该方法应用于典型三维基坑算例。研究发现,改进法得到的支护结构水平变形大于传统方法,而对内力结果影响不大;基坑平面尺寸越大,两者的变形结果差别越明显,改进法更能反映平面尺寸对基坑变形的影响。
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| 关 键 词： | 基坑 卸载 弹性抗力法 水平基床系数 |
| 收稿时间： | 2011-01-19 |
A modified beam-spring model method and its application considering unloading effect during excavation |
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| YING Hong-wei,NIE Wen-feng,GUO Lei,YANG Yong-wen.A modified beam-spring model method and its application considering unloading effect during excavation[J].Rock and Soil Mechanics,2011,32(Z1):129-133. |
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| Authors: | YING Hong-wei NIE Wen-feng GUO Lei YANG Yong-wen |
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| Institution: | 1. Institute of Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China; 2. MOE, Key Laboratory of Soft Soils and Geoenvironmental Engineering, Zhejiang University, Hangzhou 310058, China; 3. China Resources Land (Suzhou) Limited, Suzhou, Jiangsu 215001, China |
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| Abstract: | Beam-spring model method is a primary method for designing of retaining structures in actual excavation projects; it is based on foundation reaction coefficient method for calculating vertical elastic piles acted by horizontal loads. Unfortunately, the current method cannot consider the unloading effect on the soil lateral resistance coefficient and the soil deformation in the pit, so as to lead to underestimate the horizontal deformation of the retaining wall. The distribution of unloading stresses is deduced using the Mindlin solution. On the basis of previous experimental studies, the soil resistance coefficients considering the effect of excavation unloading under different ratios of unloading are derived. The development of deformation of retaining structures is divided into two stages: the first is the instantaneous unloading deformation of the soil in the pit; and the second is the deformation of retaining wall induced by the lateral earth pressure differences on the wall. Then a modified beam-spring model method is presented considering unloading stress paths and unloading deformations. Finally, the method is applied to two typical 3D numerical excavation cases. It is shown that the horizontal displacement of the wall calculated by the modified method is greater while the difference between the internal forces is quite small; the greater the excavation plane size is, the more obvious the differences between the deformation results are. The modified method can better reflect the effect of the size of the base plane on the deformation of the retaining structure. |
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| Keywords: | excavation unloading beam-spring model method lateral resistance coefficient |
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