软土地层基坑施工过程土锚索受力状态原位试验研究

In-situ Test Study on Stress State of Soil Anchor Cable in Construction Process of Foundation Pit in Soft Soil Stratum

摘要:

针对软土地层深基坑施工扰动引发锚索支护系统预应力损失及其支护效果风险演化等不确定性问题，结合温州机场大型深基坑工程，进行基坑开挖全过程土锚索预应力分布特性及其演化的原位试验。通过实时数据，系统研究基坑开挖过程锚固力变化特性、施工方式和参数对锚固力的影响规律、锚索几何参数对自身受力和作用效果的影响。结果表明，近距离土体开挖卸载对锚索体系的实时锚固力产生较大幅度的突变性影响；随基坑开挖过程，各试样锚固力呈缓慢增大趋势；锚固力的损失与增大，取决于锚索结构的几何参数，当锚索长度大于等于3倍基坑深度时，锚固力损失趋于零并呈现逐渐增加趋势。该结果对软土基坑锚索支护设计具有借鉴意义。

Abstract:

In view of the uncertainty of prestress loss and its support effect risk evolution of anchor cable support system caused by the construction disturbance of deep foundation pit in soft soil stratum, combined with the large deep foundation pit project of Wenzhou Airport, the in-situ test is carried out on the distribution characteristics and evolution of soil anchor cable prestress in the whole process of foundation pit excavation. Based on the real-time data, the variation characteristics of anchoring force in the process of foundation pit excavation, the influences of construction methods and parameters on the anchoring force, and the influence of geometric parameters of anchor cable on its own force and effect are systematically studied. The results show that the excavation and unloading of soil in short distance has a great abrupt effect on the real-time anchoring force of the anchor cable system. With the excavation process of the foundation pit, the anchoring force of each sample increases slowly. The loss and increase of the anchoring force depend on the geometric parameters of the anchor cable structure. When the length of the anchor cable is greater than or equal to three times the depth of the foundation pit, the loss of anchoring force tends to zero and increases gradually. The results can be used for the reference in the design of anchor cable support of foundation pit in soft soil stratum.