半刚性半盖挖体系临界施工荷载研究

Study on the Critical Construction Load of A Semi-rigid and Semi-capped Excavation System

深基坑半盖挖体系虽在城市轨道交通领域得到广泛应用,但为拓展施工空间,使盖板体系能承载施工及城市交通车辆荷载,梁板式半盖挖体系常演变为半刚性半盖挖体系,目前针对该体系受力与变形特性的理论研究远滞后于工程实践.因此,采用数值分析与现场测试相结合的手段,首次综合考虑盖板刚度、立柱承载力及稳定性、支撑轴力及地连墙变形等因素,对依托工程的半刚性半盖挖体系临界施工荷载及其控制因素开展系统研究.初步得出:依托工程半刚性半盖挖体系围挡内盖板行驶40t渣土车是安全可行的,其围挡内盖板所能承载的渣土车临界施工荷载为45t及该渣土车临界施工荷载的控制因素为盖板刚度.该分析结论对半刚性半盖挖体系的设计及施工具有较好的指导作用.

Although the semi-capped excavation system of deep foundation pit has been widely used in the field of urban rail transit,the beam-plate semi-capped excavation system always evolves into a semi-rigid and semi-capped excavation system in order to expand the construction space and enable the cover-plate system to bear the construction and urban traffic vehicle load.However,the present theoretical research on characteristics of the mechanical and deformation of the system is still far behind the engineering practice.By means of numerical analysis and field test,the critical construction load of the semi-rigid and semi-capped excavation system and its control factors are systematically studied for the first time while the factors such as the stiffness of cover plate,the bearing capacity and stability of the column,the supporting axial force and the deformation of diaphragm wall have been taken into account.It can be concluded preliminarily that it is safe and feasible to drive 40 t muck truck with enclosure inner cover plate of the semi-rigid and semi-cover excavation system.The critical construction load of the muck truck is 45 t,and the control factor of the critical construction load of the muck truck is the stiffness of the enclosure inner cover plate.The conclusion can be used to guide the design and construction of the semi-rigid and semi-capped excavation system.