基于大断面束合管幕法的地铁车站建造方案研究

Research on Metro Station Construction Scheme Based on Large Profile UBIT Construction Method

目的:为了在软土暗挖技术领域推广UBIT(束合管幕)施工方法,特针对应用该施工方法的大断面地铁车站建造方案进行研究。方法:以上海轨道交通23号线的某车站为工程背景,结合周边环境、道路交通、控制管线明确工作井设置、暗挖段长度及顶覆土厚度等总体方案;确定包括宽度限界、高度限界、管线排布的使用功能限界,提出采用A型车的地铁车站类矩形断面建筑设计标准;考虑预应力张拉施工阶段、土体已开挖使用阶段的两阶段受力平衡,拟合结构断面;结合束合管节节间接缝的受力特征,建立刚性板-耦合单元非线性本构模型;通过有限元手段研究断面内力变形,并进行预应力配束计算研究。结果及结论:实施中应尽量减少顶部覆土、缩短一次性管节顶进长度,以有利于控制钢管节尺寸、施工误差;大断面束合管幕法地铁车站建造应优选类矩形断面,以充分利用拱形受力特点。但值得注意的是,类矩形断面的预应力张拉,会产生显著的次生内力及变形,且其影响与曲率成正相关。针对城市轨道交通工程常见的3~5 m覆土,在内力、变形双控标准下,建立了类矩形断面预应力钢绞线的配束标准。

Objective:In order to promote the UBIT(underground bundle composite pipe integrated by transverse pre-pressing)method in the field of soft soil underground-excavation technology,research is specifically carried out focusing on the construction scheme of large profile metro station applying this construction method.Method:Taking a station on Shanghai Metro Line 23 as the engineering background,the overall scheme is defined by considering the surrounding environment,road traffic,and control pipelines,including the setting of working shafts,the length of the underground-excavation section,and the thickness of the overlying soil.The application functional limitations including width limits,height limits,and pipeline layout are determined.The design standards for metro stations with A-type trains and quasi-rectangular profile buildings is proposed.The two-stage force balance during the pre-stressing tensioning construction phase and the soil excavation use stage is considered,and the structural profile is fitted.A nonlinear constitutive model of rigid plate-coupling element is established based on the force characteristics of the coupling joints between the bundled tubes.The internal force and deformation of the profile are studied through finite element methods,and research on pre-stressing reinforcement calculations is carried out.Result&Conclusion:During implementation,efforts should be made to minimize the topsoil cover and reduce the length of one-time pipe jacking to control the dimensions of steel pipe sections and construction errors.The construction of large profile metro stations using UBIT method should preferably choose a quasi-rectangular profile to fully utilize the arching force characteristics.However,it is noteworthy that pre-stressing tensioning in quasi-rectangular profiles generates significant secondary internal forces and deformations,and the impact is positively correlated with curvature.For common soil cover of 3 to 5 meters in urban rail transit projects,under the standards of both internal force and deformation control,a standard for pre-stressing reinforcement arrangements in quasi-rectangular profile is established.