大型锚碇基础围护工程冻结帷幕力学性态研究

Research on mechanical properties of frozen curtain in large anchorage foundation pit engineering

冻结围护是利用人工制冷技术,使地层中的水结冰,将天然土层变成冻土作为围护挡土止水的新技术。依据冻结基本原理,在大型锚碇深基础中采用排桩内支撑结构并结合冻结帷幕止水是一种新的基坑围护形式,含水土层冻结后形成的冻结帷幕具有良好的封水性能,冻土墙刚度和强度较原土层有很大的提高且质量易于控制。相对于常规围护工程,冻结围护结构的冻胀力学特性复杂且研究资料贫乏,因此,其力学性状的研究将进一步完善冻结围护技术理论,保障基础工程顺利安全进行。通过对锚碇基础围护工程冻结帷幕温度场-应力场耦合的三维非线性数值模拟分析研究,得到冻结围护工程中冻结帷幕的冻胀力学性状特征,结合大型锚碇基础冻结围护工程实例的现场测试成果分析,验证数值模拟分析方法结果的合理性以及冻结围护技术的可靠性,研究成果将为今后冻结围护技术的工程推广应用提供理论基础。

Ground freezing enclosure is a new technique that makes water in soil be ice by the way of artificial refrigeration, thus change original soil to be frozen retaining wall and waterproof curtain in foundation pit engineering. Based on the freezing principle, frozen soil curtain formed from aquifer has some super performances such as excellent waterproof, higher rigidity and strength, etc. As a new structure system of deep foundation pit in the large anchorage engineering, its important features include that piles and internal strut are used to be exterior-protected construction while frozen soil curtain hold back ground water. Compared with the conventional supporting projects, previous research data of frost mechanical properties in envelope works are always poor. Therefore frost heave mechanical characteristics of frozen curtain are obtained from simulation of three-dimensional coupling numerical nonlinear analysis of the fields of temperature and stress; and the conclusions are verified by field test data in foundation pit engineering. Research achievements may provide theoretical basis of applications in the future, not only for its rationality in analysis and results but also its reliability in techniques and methods.