Wall deflection induced by pre-excavation dewatering under different construction conditions
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摘要: 已有工程实测表明,基坑开挖前的预降水可引起围护结构和周边环境厘米级的变形,但相关的研究报道还是偏少,基坑预降水引起的基坑变形性状仍未被全面揭示。采用ABAQUS建立考虑降水井瞬态降水的二维流固耦合有限元模型,研究了基坑宽度和预降水深度对预降水引发变形的影响。研究表明,预降水引发的最大地连墙侧移及地连墙侧移沿深度发展范围随着基坑宽度、降水深度的增加而增大,并且存在临界基坑宽度使得在临界宽度范围内,最大地连墙侧移及地连墙侧移深度范围随基坑宽度的增加而快速增加,而超过临界宽度后,基坑宽度对地连墙侧移的影响会明显减弱;同时存在临界降水深度,使得在其范围内,最大地连墙侧移随预降水深度的增加而变化缓慢,而超过临界降水深度后,降水深度的增大将引起最大地连墙侧移发生较大幅度的增长。Abstract: The existing field measurements show that the deformation of retaining wall and surrounding environment induced by pre-excavation dewatering can reach centimeter level, but the relevant researches are still less. The behaviors of pit deformation induced by pre-excavation dewatering are not been fully revealed. In this study, a two-dimensional fluid-solid coupled finite element model is established using ABAQUS to investigate the influences of excavation width and dewatering depth on wall deflection. The results indicate that the maximum wall deflection (δhm) and the distribution range of wall deflection along depth (Hc) become larger with the increase of excavation width and dewatering depth. There is a critical excavation width, within which δhm and Hc increase fast with the increase of excavation width. However, with the excavation width being greater than the critical excavation width, the influences of excavation width on wall deflection are weak obviously. Besides, there is a critical dewatering depth, within which δhm change slowly with the increase of dewatering depth. However, with the dewatering depth being greater than the critical dewatering depth, the increase of dewatering depth will lead to a substantial growth of the maximum wall deflection.
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