盾构法和浅埋暗挖法结合建造地铁车站模型试验的方案设计

以北京地铁通用乙级车站为例,为了对盾构法和浅埋暗挖法结合建造塔柱式地铁车站施工过程进行模型试验,设计模型试验方案。方案为:采用的几何比为1∶10,材料容重比为1∶1;模拟对象为由每侧3个塔柱和2个横通道组成的隧道,模型尺寸为6.5 m×1.8 m×2.88 m,采用清华大学三维地质力学模型试验台架;模型介质材料分别模拟地表杂填土层,粉质黏土、粉土、粉细砂互层和车站隧道底部的卵石圆砾层;在模型内部适当位置布设量测仪器,进行车站隧道周围土体位移、盾构管片收敛变形和切向应变、立柱支撑和预应力钢筋上的应变等的量测;模型采用容重控制法制作,总重约60 t;开挖过程和支护系统按照实际施工过程进行详细模拟。采用设计的模型试验方案进行施工,能够保证车站洞室在整个施工过程中的安全和稳定。

Scheme Design on the Model Test of the Metro Station Constructed by Shield Method and Shallow Mining Method

Based on Beijing metro station GM B, model test scheme was designed for pylon shaft metro sta-tion constructed by shield method and shallow mining method. The geometric scale of the model test was 1:10, and the material bulk density scale was 1 : 1. The Model tunnel included 3 pylon shafts and 2 cross channels on each side. The model size was 6. 5 m×1.8 m×2. 88 m, and three-dimensional geomechanical model test bench of Tsinghua University was used. The model stratums mainly included miscellaneous fill-ing soil surface, interaction stratum of silty clay, silt and fine sand and pebble round gravel at the bottom of station tunnel. The instruments were used to measure the displacement of the soil around station tun-nel, the convergence and strain of the shield segments, the strain of steel support, and the strain of pre-stress tight. The model was produced by bulk density control method, and the total weight was 60 t. The excavation and support system were simulated according to the actual construction process in detail. The results indicate that the metro station will be safe and stable during the construction process by the model test scheme.