高压旋喷预应力锚索在苏州某大型深基坑工程中的应用

Application of Prestressed Ground Anchor with High Pressure Grout in a Large Deep Excavation in Suzhou City

预应力锚索技术应用在全国范围内已非常广泛,在土质松软地区以及深基坑中当单根锚索的承载力较大时,可采用高压旋喷形成大直径锚固端以增加抗拔力[1-5]。锚索的隐蔽特性导致其质量不易保证且施工方大多不按照规定进行基本试验,故苏州地区深大基坑中锚索应用有限。在苏州大学附属儿童医院园区总院项目深基坑设计中采用高压旋喷预应力锚索,严格按照规范规定的安全系数设计,制定锚索基本试验方案,各方规范运作,在安全、经济和工期方面均取得显著效果。

Prestressed ground anchors have received wider applications in China recently.When the ground anchor is applied in the deep excavation with high pullout capacity requirements,high pressure jet grout can be applied in the bond zone of the anchor.However,due to underground feature of the grouting zone,it is difficult for the quality assurance and quality control during the construction.Further,the required load tests for the ground anchors are usually not conducted in the practice.As a result,the application of ground anchors for the deep excavation in Suzhou area is relatively rare.This paper presents a case history of a deep excavation support design for the General Children’s Hospital building.High pullout capacity prestressed ground anchor with high pressure jet grout method was used.Both the design and testing required by the code were strictly followed and the results were satisfactory.