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采用自主研制的Φ800 mm土压平衡盾构掘进试验系统,对砂卵石与砂土地层开展室内缩尺掘进试验研究,以分析土压平衡盾构掘进对地层的扰动特征;同时,针对室内缩尺掘进试验,开展离散元数值模拟以分析盾构掘进开挖面的变形与破坏形态。研究表明:砂土地层地表沉降曲面自上而下呈现逐渐收缩的“圆形漏斗”状,砂卵石地层地表沉降曲面自上而下呈现逐渐收缩的“V型河谷”状;砂卵石地层地表横断面沉降槽宽度系数相比砂土地层要小;2种地层地中沉降槽宽度参数都随地中深度比的增加而呈线性增大,相同深度比条件下砂卵石地层地中沉降槽宽度参数要小于砂土地层;砂土地层沉降时间效应曲线较为渐进和连续,而砂卵石地层则呈现突变性;2种地层开挖面破坏形态均为烟囱状,但砂卵石地层的开挖影响范围无论在横向还是纵向上都要小于砂土地层。
Using the self-developed Φ800 mm earth pressure balance shield tunneling test system, the experiment of scale reduction excavation in sand, gravel and sand stratum was carried out to analyze the disturbance characteristics of earth pressure balance shield tunneling to the formation. At the same time, Tunneling test and carry out discrete element numerical simulation to analyze the deformation and failure modes of shield tunneling face. The results show that the surface subsidence curved surface of sand strata shows a gradually shrinking “circular funnel” shape from top to bottom. The surface subsidence curved surface of sand and gravel strata shows a gradually shrinking “V-shaped valley” shape from top to bottom; sand The width coefficient of settlement channel on surface cross-section of pebble stratum is smaller than sand stratum. The width parameters of settlement stratum in two kinds of stratum all increase linearly with the increase of depth-to-depth ratio. Under the same depth, the settlement of sand-gravel stratum The groove width parameter is smaller than that of sandy soil; the sedimentation time-effect curve of sandy soil is more gradual and continuous, while the gravel stratum shows mutation; the failure modes of the two kinds of formation are chimney-shaped, but the excavation of sand- The influence range is smaller than sandy soil strata both horizontally and vertically.