基于岩爆危险性评价的川藏铁路某深埋硬岩隧道线路方案比选研究

川藏铁路穿越区域地形起伏大，区域地质构造作用强烈，隧道建设中面临的高地应力问题异常复杂，特别是深埋硬岩隧道中的岩爆灾害问题，成为制约选线、设计乃至施工建设的难题。由于隧道工程地质条件复杂，如果岩爆评价指标针对性不强，往往会造成评价结果与实际偏差较大。通过综合分析影响岩爆的关键因素，选取岩石单轴抗压强度与洞壁最大主应力比、洞壁最大切向应力与岩石单轴抗压强度比、岩石强度脆性系数、岩石弹性能指数及岩体完整性系数建立了岩爆评价指标体系。根据熵权法确定各指标权重，基于理想点的基本理论及计算规则，构建了一种岩爆危险性评价模型。通过计算各里程段与理想点的距离，对新建川藏铁路某隧道的3种线路方案进行岩爆风险评估的综合比选。研究结果表明B线路总岩爆段落占比24.9%，其中不可控岩爆段落占比13.4%，比另外两条比选方案低4%左右，综合对比B线路为最优方案。该方法可为深埋硬岩隧道地质综合选线提供必要的科学依据和技术支撑。

Route selection of deep-lying and hard rock tunnel in the Sichuan-Tibet Railway based on rock burst risk assessment

The large terrain undulations and strong regional geological structures are the typical characteristics along the Sichuan-Tibet Railway. The high ground stress problem in tunnel construction is extremely complex, especially the rockburst problem in deep-lying and hard rock tunnels, which restricts route selection schemes and becomes a major difficult problem of construction. Because of the complex geological conditions of the tunnel engineering, the evaluation results often deviate from the actual situation if the rockburst evaluation index is not pertinent. The key factors of rockburst is considering comprehensively, and five factors are selected as the evaluation indexes, including the ratio of the uniaxial compressive strength of rock to the maximum main stress of the surrounding cave wall, the ratio of the maximum tangential stress of the surrounding cave wall to the uniaxial compressive strength of rock, the ratio of compressive to the tensile strength of rock, the elastic strain energy index, and the intactness index of rock mass. The entropy weight method is used to determine the weight of each index, and a rock burst risk assessment model is constructed based on the basic theory and calculation rules of the ideal point method. By calculating the distance between each mileage section and the ideal point, a comprehensive comparison of rock burst risk assessment is carried out on three route plans of a tunnel on the Sichuan-Tibet Railway. The results show that the total rock burst sections of route B is 24.9%, and the uncontrollable rock burst sections account for 13.4%. The route B is about 4% lower than the other two alternative schemes. The route B is determined as the optimal plan according to the impact of rock burst disasters. This method can provide a new scientific basis and technical support for the comprehensive geological selection of deep-lying and hard rock tunnels.