公路隧道下穿3层采空区施工模型试验研究

发布时间：2018-11-25 13:54

【摘要】：隧道近接下穿3层倾斜采空区施工容易引起围岩松动范围叠加、增大,地层的非对称移动易使隧道结构受非对称荷载作用。采取室内模型试验模拟公路隧道下穿3层煤层采空区的开挖过程,通过埋设土压力盒、电阻应变片、地中位移计,测量隧道开挖过程中初期支护受力和地层位移。试验结果表明,一定范围倾角越小,隧道测试断面开挖过程中的采空区地层的沉降速率越大,时程曲线越陡,后期沉降值较大,扰动程度随地层与隧道距离的增加先增大后减小;一定倾角的采空区会使离采空区较远一侧的仰拱处土压力明显增大,结构设计时应予以加强;在15°~30°范围内,倾角对围岩压力的分布形态、量值影响不大,对钢拱架内力影响较大,倾角越大,初期支护偏心距越大。对于Ⅳ级围岩,双车道隧道近接(2 m)3层采空区地层施工时,建议先进行超前支护,再采用台阶法开挖,进尺不大于1 m,钢拱架间距不大于0.5m。
[Abstract]:It is easy to cause the surrounding rock loosening range superposition and increase in the construction of the tunnel through the three-story inclined goaf near the tunnel. The asymmetric movement of the stratum easily causes the tunnel structure to be subjected to asymmetric loads. Indoor model test was used to simulate the excavation process of goaf in three coal seams under highway tunnel. The initial support force and stratum displacement were measured by embedding earth pressure box, resistance strain gauge and ground displacement meter. The test results show that the smaller the dip angle in a certain range, the greater the settlement rate, the steeper the time-history curve and the larger the settlement value in the later stage of excavation of the tunnel test section. The disturbance degree increases first and then decreases with the increase of the distance between the layer and the tunnel. The goaf with a certain inclination angle will obviously increase the earth pressure in the invert of the far side of the goaf, which should be strengthened when the structure is designed. In the range of 15 掳~ 30 掳, the angle of inclination has little effect on the distribution of surrounding rock pressure, but has a greater effect on the internal force of steel arch frame. The greater the inclination angle, the greater the eccentricity of initial support. For the fourth grade surrounding rock, when the two-lane tunnel is close to (2 m) 3 layer goaf stratum construction, it is suggested that the advance support should be carried out first, then the step method should be used to excavate, the advance length is not more than 1 m, and the steel arch frame spacing is not more than 0.5 m.
【作者单位】：西南交通大学交通隧道工程教育部重点实验室;
【基金】：国家自然科学基金(No.51278422) 国家科技支撑计划课题(No.2012BAG05B03) 四川省青年科技基金(No.2012JQ0021) 中央高校基本科研业务费专项资金(No.SWJTU11ZT33)
【分类号】：U451.5

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