地下工程开挖卸荷既有桩基承载响应物理模拟及新进展

地下工程开挖卸荷引起的灾变问题一直是社会高度关注的问题之一,近年来中国多地发生了由基坑开挖或隧道建设诱发的地面变形、桩基倾斜偏位及建筑物垮塌等灾害事故,威胁人们的生命和财产安全。简要介绍传统地下工程开挖卸荷物理模拟存在的不足,对比概述了近20a间国内外有关基坑、隧道开挖对桩基影响的典型试验方法和试验装置(小比尺模型试验和离心机试验)。重点设计提出了一种地下工程开挖卸荷既有桩基承载响应室内综合模拟试验装置,并对模型设计原理及技术特点进行了分析,同时开展了邻近基坑开挖对既有工程桩水平承载力影响及工程阻隔物对地下水阻挡作用影响两类问题试验研究。最后,对卸荷桩未来的研究方向提出了一些建议和展望。

Model tests and new progress of pile response due to underground excavations

The disaster from the unloading effects induced by underground excavations has always been one of the high-concern issues. In recent years, a series of ground deformation, pile foundation tilt, or building collapse cases have taken place in China, and sometimes they even threaten people's lives and property. The imperfection of the conventional model tests for simulating underground excavations is introduced, and the typical experimental test methods and test devices including small-scale and centrifuge models corresponding to excavation of foundation pit and tunneling in the past two decades are briefly compared. In this study, a new testing apparatus for pile load response undergoing underground excavations is proposed, and its design principles and technical characteristics are analyzed. Using the test boxes, the studies on the lateral pile response to adjacent excavation and the blocking effect of a barrier on the flow of groundwater are conducted. Finally, some suggestions and prospects about the future study on unloading piles are put forward.