框架逆作深基坑变形特性离心模型试验

Centrifuge Model Test Investigation on Deformation of Deep Excavation with Frame Top Down Method

摘要:

以某超大型深基坑工程为背景，通过离心模型试验比较了新型框架逆作法与传统逆作法的施工方案基坑变形控制的效果；基于试验结果，研究了地表最大沉降与围护结构最大侧移之间的关系，以及地表沉降大小和影响范围.试验结果显示：框架逆作基坑地表最大沉降基本为围护墙最大侧移的0.35～0.70倍，而无支撑暴露时间对二者比值的大小有一定影响；基于实测总结的国内外多种经验地表沉降预测方法并未能很好地预测试验结果；框架逆作法与传统逆作法施工方案基坑变形控制的效果大致相当，框架逆作法方案可以达到有效控制基坑变形的目的，该结论对于框架逆作法在实际工程中的推广应用具有重要参考价值.

Abstract:

Taking one large deep excavation as the research background, this paper compares the effect of deformation control of the frame top down scheme and the traditional top down scheme through centrifugal model tests. In addition, it further studies the relationship between the maximum wall deflections and the maximum ground settlements, as well as the size and scope of ground settlements. The test results show that the excavation induced maximum ground settlements using frame top down method δvm is 0.35～0.7 times of the excavation induced maximum wall deflection δhm, and unsupported exposure time has some effect on δvm/δhm. The predicted results by empirical prediction method based on measured data is much different from the test results. Excavation induced performance using frame top down and traditional top down construction schemes is similar, and the excavation induced performance using frame top down scheme can be controlled effectively. The conclusion of this paper has significant referential meaning for designs and constructions of actual engineering.