郑州地铁浅埋暗挖通道的地面变形规律研究

发布时间：2019-06-11 21:51

【摘要】：随着我国经济的快速发展,越来越多的人涌入大城市,特别是北京、上海、广州、深圳等一线城市和省会城市,这直接导致了城市道路的拥堵,因此越来越多的城市开始修建地铁,以缓解交通压力。浅埋暗挖法作为地铁施工的主要施工手段之一,由于不需要对施工场地周边建筑物拆迁、对地面交通干扰较少、而且成本较低,因此在地铁建设过程中被广泛应用。但浅埋暗挖施工时仍会对地层产生扰动,使地表和土层发生变形,严重时会使地下管线开裂、建筑物倾斜、地面不均匀沉降等,这些都会对人们的生命财产安全造成影响,因此对浅埋暗挖通道在开挖时引起地面变形规律的研究是十分必要的。郑州轨道交通1号线二期新郑州大学站1号、2号出入口浅埋暗挖通道由于施工场地周边管线较多并且与通道距离较近,在通道开挖前无法使用大管棚进行超前支护,因此提出使用超前小导管注浆技术代替大管棚进行超前支护的方案,并且对通道开挖的整个过程进行了监控测量。本文主要进行了两方面的研究:一是采用FLAC3D对超前小导管注浆前后浅埋暗挖通道的施工过程进行了模拟,并结合现场实际监测数据,验证了郑州地铁浅埋暗挖通道施工时采用超前小导管注浆技术进行超前支护的可行性,分析了施工过程中地面变形特点和变化规律;二是统计浅埋暗挖通道顶部交通量,并且对车辆通过通道时的加速度进行实测,采用FLAC3D软件对交通荷载作用下浅埋暗挖通道的地面变形规律进行模拟,并与静荷载作用下的结果、实测数据对比,分析了交通荷载对于浅埋暗挖通道的影响。本文主要得到了以下结论:(1)通过对实际监测数据的分析,得到施工过程引起的地表沉降变化规律基本是按照微小沉降阶段→急剧沉降阶段→缓慢沉降阶段→沉降稳定阶段变化的,并且施工过程中地表的累计沉降量和沉降速率均未超出预警值,表明郑州地铁施工时采用超前小导管注浆技术作为浅埋暗挖通道的超前支护是可行的。(2)采用FLAC3D对超前小导管注浆前后浅埋暗挖的施工过程进行了模拟,对DB1横断面进行分析,得到采用超前小导管注浆对地层加固后地表最大沉降为-3.81mm,未进行小导管注浆的地表最大沉降-5.67mm,前者减小了1.86mm,是加固前地表最大沉降的32.8%,对工程实例的结果进行了验证,说明了超前小导管注浆能够明显降低地表沉降,可以在郑州地铁施工时代替大管棚作为超前支护。(3)首先对1号出入口浅埋暗挖通道上部交通流量进行了统计,然后用数据采集仪实测了重车(包含公交车、水泥搅拌车、碴土车等)等引起的地表和通道顶部加速度时程曲线,将车辆动荷载简化处理为能反映车辆荷载周期特点、行车速度影响、以及几何不平顺性质的类似激振的形式,并用FLAC3D对地表和通道顶部的加速度进行了数值模拟,验证了动载模型的合理性。(4)采用FLAC3D软件对施工阶段各个工况重车动荷载引起的地表变形进行了数值模拟,并与静载模拟结果和实际监测数据(不考虑重车动载)进行了对比,结果表明,考虑重车动载沉降的最大值比静载模拟结果和实际监测数据增大了16.3%,说明重车荷载会对地表沉降产生较大的影响,因此郑州地铁进行浅埋暗挖施工时应该考虑重车荷载的影响,可作为今后类似工程的施工和运营阶段监测、评价的理论支撑和技术参考。
[Abstract]:With the rapid development of our economy, more and more people are pouring into big cities, especially in the first-line cities and provincial capitals such as Beijing, Shanghai, Guangzhou and Shenzhen, which directly leads to the congestion of the urban roads, so more and more cities have started to build the subway to relieve the traffic pressure. As one of the main construction methods of the subway construction, the shallow-buried underground excavation method is widely used in the construction of the metro, because the demolition of the surrounding buildings in the construction site is not required, the interference of the ground transportation is less, and the cost is lower. but during the shallow-buried underground excavation construction, the formation is disturbed, the surface and the soil layer are deformed, the underground pipeline is cracked, the building is inclined, the ground is not uniformly settled, and the like, Therefore, it is necessary to study the ground deformation law of the shallow-buried underground excavation channel in the excavation. No.1 and No.2 of the second phase of the Phase II of Zhengzhou Rail Transit Line 1, the shallow-buried underground excavation channel at the entrance and exit of Zhengzhou Rail Transit Line 1 cannot be pre-supported by using the large pipe shed before the excavation of the channel due to the large number of pipelines around the construction site and the distance to the channel. Therefore, it is proposed that the advanced small-pipe grouting technology is used instead of the scheme of the advanced support of the large-pipe shed, and the whole process of the channel excavation is monitored and measured. This paper mainly studies two aspects: one is to use FLAC3D to simulate the construction process of the shallow-buried deep-cut channel before and after the advanced small-pipe grouting, and to combine the real-time monitoring data of the site, The feasibility of adopting advanced small-pipe grouting technology for advanced support during the construction of the shallow-buried underground excavation channel of Zhengzhou metro is verified, the characteristics and the changing law of the ground deformation in the construction process are analyzed, and the traffic volume at the top of the shallow-buried underground excavation channel is statistically analyzed, And the influence of the traffic load on the shallow-buried underground excavation channel is analyzed by using the FLAC3D software to simulate the ground deformation law of the shallow-buried underground excavation channel under the action of the traffic load, and comparing the measured data with the measured data under the action of the static load. In this paper, the following conclusions are obtained: (1) Through the analysis of the actual monitoring data, the change law of the surface settlement caused by the construction process is basically changed according to the sedimentation stability of the slow-settling stage during the rapid settling stage of the micro-settlement stage, And the accumulated settlement amount and the settlement rate of the earth surface in the construction process do not exceed the early warning value, so that the advanced support of the advanced small-pipe grouting technology as the shallow-buried underground excavation channel during the construction of the Zhengzhou subway is feasible. (2) The construction process of the shallow-buried deep excavation before and after the advanced small-pipe grouting is simulated by the FLAC3D, and the cross section of the DB1 is analyzed, the maximum settlement of the ground surface after the formation is reinforced by the advanced small-pipe grouting is-3.81 mm, and the maximum settlement of the surface of the non-small-pipe grouting is 5.67mm, The former is reduced by 1.86 mm, which is 32.8% of the maximum settlement before the reinforcement, and the results of the project are verified. The results show that the advanced small-pipe grouting can obviously reduce the surface settlement, and can replace the large-pipe shed as the advance support in the construction of the Zhengzhou subway. (3) Firstly, the traffic flow of the upper part of the shallow-buried underground excavation channel of No.1 entrance is counted, and then the time-history curve of the top acceleration of the surface and the channel caused by the heavy vehicle (including the bus, the cement mixer, the ballast soil car, etc.) is measured by the data acquisition instrument. The vehicle dynamic load is simplified to reflect the characteristics of the vehicle load period, the influence of the driving speed and the similar excitation of the geometric irregularity, and the acceleration of the surface and the top of the channel is numerically simulated by the FLAC3D, and the rationality of the dynamic load model is verified. (4) The surface deformation caused by heavy vehicle dynamic load at various working conditions in the construction stage is simulated by the FLAC3D software, and compared with the static load simulation result and the actual monitoring data (not considering the heavy vehicle dynamic load), the result shows that, Considering that the maximum value of the dynamic load settlement of the heavy truck is increased by 16.3% than the static load simulation result and the actual monitoring data, the influence of the heavy truck load on the surface settlement is explained, so that the influence of the heavy vehicle load should be taken into consideration in the construction of the shallow-buried underground excavation of the Zhengzhou subway, It can be used as the theoretical support and technical reference for the monitoring and evaluation of the construction and operation phases of similar projects in the future.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U231.3

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