土岩组合深基坑围护结构受力与变形特性分析——以青岛海天中心深基坑为例

为了研究土岩组合二元地层超基坑受力、变形和邻近建筑沉降随基坑开挖的演化规律,依托于青岛海天中心城市综合体桩锚支护结构体系超深基坑工程,对预应力锚索轴力、基坑水平和竖向位移以及周边建筑物沉降进行了实时监测。结果表明,基坑开挖期间内,预应力锚索轴力随时间的变化规律主要分快速下降、稳定变化和基本稳定3个阶段,锚索轴力平均损失率约为15.08%；基坑最大水平位移为12.30 mm,最大竖向位移为11.01 mm,基坑临近建筑物最大沉降量为1.2 mm,远小于设计和现行《建筑基坑工程监测技术标准》的容许变形值,说明桩锚支护结构体系可以有效控制基坑变形,确保毗邻建筑物安全；同时表明该基坑的支护设计方案有较大的优化空间,从而节约工程成本。研究成果对相似地质条件的超深基坑围护结构设计具有重要参考价值。

Experimental analysis of stress and deformation characteristics of pile-anchor retaining structure in soil-rock combination ultra-deep foundation pit

In order to study the evolution law of force and deformation of super foundation pit and settlement of adjacent buildings with foundation pit excavation in soil-rock combination binary stratum. , Based on the super deep foundation pit project of pile-anchor supporting structure system of Qingdao Haitian-Central Urban complex, the axial force of prestressed anchor cable, horizontal and vertical displacement of foundation pit and settlement of surrounding buildings were monitored in real time. The results show that the axial force of prestressed anchor cable varies with time in three stages: rapid decline, stable change and basic stability. The average axial force loss rate of anchor cable is about 15.08%. The maximum horizontal displacement of the foundation pit is 12.30 mm, the maximum vertical displacement is 11.01 mm, and the maximum settlement of the adjacent buildings is 1.2 mm, which is far less than the allowable deformation value of the design and the current "Monitoring Technical Standard for Building Foundation Pit engineering", indicating that the pile-anchor retaining structure system can effectively control the deformation of the foundation pit and ensure the safety of adjacent buildings. At the same time, it is shown that the design scheme of the foundation pit has a large space for optimization, so as to save the project cost. The research results have important reference value for the design of ultra-deep foundation pit retaining structure under similar geological conditions.