新型H型钢支撑体系设计分析及工程应用研究

Design analysis and engineering application research of new H-section steel support system

新型H型钢支撑体系由H型钢支撑、钢围檩、系杆、千斤顶、立柱和托梁等组成,单根H型钢支撑通过系杆连接,系杆与H型钢支撑位于同一水平面,形成平面桁架体系。与传统钢支撑体系相比,新型H型钢支撑采用全螺栓装配连接,可以任意组合、拼装,施工便捷。为了研究新型H型钢支撑体系的安全性能及其在深大基坑工程中的适用性,以上海静安府项目基坑工程为背景,对基坑围护桩变形和H型钢支撑轴力进行现场监测,分析基坑围护桩顶位移、桩体水平位移和新型H型钢支撑轴力的变化规律。结果表明:基坑围护桩顶位移和桩体变形与基坑开挖工况和基坑底板浇筑速度密切相关;新型H型钢支撑轴力受气温影响比较明显,且气温越高,单位温度变化对其轴力的影响越明显。通过对新型H型钢支撑区域与钢筋混凝土支撑区域围护桩变形进行对比分析发现,新型H型钢支撑区域围护桩顶和桩体位移的变化规律及最终变形值均与钢筋混凝土支撑区域基本一致,且所有监测数据都在安全范围以内。

The new H-section steel support system is composed of H-section steel supports,steel purlins,tie rods,jacks,columns and joists,etc.A single H-section steel support is connected by a tie rod,and the tie rod and the H-section steel support are located on the same horizontal plane,forming a plane truss system.Compared with the traditional steel support system,the new H-section steel support adopts full bolt assembly connection,which can be combined and assembled arbitrarily,and the construction is convenient.In order to explore the safety performance of new H-section steel support system and its applicability in deep and large foundation pit project,taking Jinganfu foundation pit project in Shanghai as background,the deformation of the foundation pit retaining pile and the axial force of the H-section steel support were monitored on-site.The change laws in the top displacement of the foundation pit retaining pile,the horizontal displacement of the pile body and the axial force of the new H-section steel support were analyzed.The results show that the top displacement of the foundation pit retaining pile and deformation of the pile body are closely related to the excavation depth and foundation slab concreting speed.The axial forces of new H-section steel support are influenced obviously by temperature,and the higher the temperature,the more obvious the influence of unit temperature change on its axial force.Through the comparative analysis of the deformation of the retaining piles in the new H-section steel supporting area and the reinforced concrete supporting area,it is found that the changing law of the top displacement of the retaining pile and final deformation value of the pile body in the new H-section steel supporting area are basically the same as that of reinforced concrete support area,and all of the monitoring data were within the security range.