拆除初支施做顶拱二衬阶段是保障PBA工法整体施工安全的关键施工步.为了更好地控制该阶段沉降,降低受力转换,提高施工安全性,本文依托长春地铁2号线解放大路车站建设项目,采用现场实测与数值模拟相结合的方法,提出一种改进的PBA工法初支扣拱阶段施工方案,并从开挖方法、施工顺序、支护措施、受力情况及工程量等多个方面比较改进前后的施工方案,以及从安全、质量、进度、效益、受力情况和可操作性等角度阐述了改进方案的优劣.此外,为了提高数值模拟的准确性,采用高度还原施工现场岩土力学特性的基于遗传算法优化支持向量机(GA-SVM)的位移反分析法获取相应岩土力学参数.主要结论有:反演得到的岩土参数结果与实地勘测值的相对误差均小于5％,证明了该方法的可行性;改进方案在工程量、安全、质量、进度和可操作性等方面均好于原方案,但改进方案的受力情况更为复杂;改进方案的最大受力位置发生了改变,改进方案施工过程中的最大应力更大,但都小于混凝土结构的设计强度,符合施工要求;改进方案的总地表沉降量比原方案减少4.3％,初支扣拱和施做二次衬砌阶段的沉降比原方案减少38.5％,可见顶拱下方洞室开挖净空的减小对于控制拱顶沉降效果显著.

为了对比分析不同地下水位下地铁车站在施工过程中的沉降变化情况,以长春地铁2号线解放大路车站为实际依托工程,建立了该地铁车站的有限元模型,并且将有限元计算结果与现场实测的施工沉降数据进行对比分析,验证了有限元模型的可靠性.分析了地铁车站中轴线上方的地表沉降在施工过程中的变化情况,并对上导洞、中导洞及1、2洞室拱顶沉降在施工过程中的变化情况进行了分析.通过定义3种不同地下水位工况,将不同地下水位下地铁车站的施工沉降曲线进行对比分析.结果 表明:地铁车站中轴线上方地表沉降的有限元计算结果和实测数据的最大误差仅为5.6％,地铁车站中轴线上方的地表沉降量呈现出阶梯式的变化趋势,随着地下水位高度的下降,拱顶沉降量的增长幅度存在突变情况.

地铁开挖过程中引起的地表沉降对周边建筑及道路有很大的影响,浅埋暗挖风道与主体交叉段的施工是工程中的重难点工序,为控制施工过程中地表沉降量,并对施工进行指导,做出以下研究:以长春地铁解放大路换乘工程为依托,采用FLAC-3D程序数值模拟的方法对CRD风道转入PBA工法车站主体进洞施工进行优化分析;通过对比双拱挑高进洞方案、加强环梁进洞方案与直接进洞方案在风道和主体开挖阶段地表沉降量,发现在风道开挖阶段,双拱挑高进洞方案沉降量较小,而主体开挖阶段,加强环梁进洞方案沉降量较小,得到如下结论:(1)双拱挑高进洞方案在风道开挖阶段对地表沉降控制较好;(2)加强环梁进洞方案在主体开挖阶段对地表沉降控制较好.

Seismic energy dissipation method belongs to passive control of structural vibration control technology,which is widely used because of its advantages in the engineering construction with obvious seismic effect.According to the characteristics of space truss structure damping,it is very necessary to apply energy dissipation and isolation technology to gird structure,grid shell structure,reducing the destruction of these structures in the earthquake.The space truss structure is located in Qingdao,because the seismic fortification intensity of Qingdao area are promoted from original 6 to 7 degrees,optimization and upgrading must be carried on original structure,enabling it meet the seismic requirements in 7 degrees by the use of energy dissipation technology.Results was compared between before and after the application of energy dissipation damper,it shows that:the energy dissipation and isolation technology can effectively reduce the earthquake response of space truss structure,a seismic performance is promoted,which satisfies the seismic require-ments in 7 degrees fortification district.

依托长春地铁解放大路站工程,采用数值模拟与现场实测相结合的方法,建立地铁出入口下穿既有消防水柜数值模型,通过流固耦合方法模拟整个施工过程,对消防水柜蓄水量与施工风险之间的关系进行研究,并采用层次分析法对多种注浆方案进行研究,提出最佳施工方案,来指导实际工程,从最终的施工效果来看,方案切实可行.

The construction method of space truss structure of sales office is introduced, which located at one new city of Qingdao, and unloading simulation and monitoring for the space truss structure were done. For the particularity of space truss structure of this large?area monomer multipoint support, combining with the characteristics of the space truss structure, the monitoring scheme of space truss structure was designed, including monitoring conditions,arrangement of measuring points and monitoring method, compared with the analysis results of the theory of finite element software MIDAS/Gen,to verify the safety of the structure under the gravity load. The comparisons between theoretical data and monitoring data during the whole process of unloading were done, a certain reference was provided for security design of soft and large span of space truss structure. Finally, considering the construction deviation in construction process of the spatial truss structure, the reliability analysis was done, the results show that the space truss structure has higher reliability.