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通过等代圆法将侧向扩挖隧道断面简化为双连通域问题,结合复变函数理论Schwarz交替法推导出了侧向扩挖隧道复应力函数的具体形式,并以深圳横龙山隧道超大异形断面(跨度29.171m,高跨比0.45)侧向扩挖工程为例,通过数值计算对单次扩挖宽度、围岩应力和位移特征展开研究。结果表明:单次扩挖宽度为4m时最为适宜,三次分步扩挖产生的二、三、四次应力状态均有不同程度的变化,最大应力和位移值出现于双洞近接施工段且主洞三次扩挖产生的平均拉、压应力值均大于扩挖洞,拱顶应力限差控制在4%以内,计算结果具有较高的精度。
By means of the equivalent circular method, the cross-section of lateral expansion tunnel is simplified as a dual connectivity problem. Combined with the Schwarz alternating method of complex function theory, the concrete form of the complex stress function of lateral expansion tunnel is deduced. (29.171m in span and 0.45 in high span) lateral excavation project as an example, the single width of excavation, the stress and displacement characteristics of surrounding rock are studied through numerical calculation. The results show that the optimum width of single excavation is 4m. The second, third and fourth stress states produced by three times of incremental excavation have different degrees of change, and the maximum stress and displacement occur in the adjacent construction of double holes and the main The average tensile and compressive stress values produced by three times of dilatancy are larger than that of dilapidated dilatancy and the stress limits of vault are controlled within 4%, and the calculation results have higher accuracy.