铁路穿越盐岩采空区地面沉降预测及工程处理措施研究

Study on the Prediction of Ground Subsidence Induced by Solution Mining and the Engineering Treatment Measures for Railways Passing Through the Mine Field

广州枢纽东北货车外绕线铁路拟通过开采20余年的盐矿区,矿区地下已形成大面积饱水采空区,铁路工程安全风险大,合理的工程处理措施需要建立在矿区现状地面沉降和矿区终采后地面沉降的分析上。采用自然邻域法插值获取了现状地面沉降等值线,结果显示截止到2015年3月,矿区地面已形成两个累计沉降均达1 m的沉降中心;采用数值方法预测矿区终采后地面最大沉降量约2.4 m。基于此,研究制定了采空区铁路工程的主要工程处理措施,包括路基沉陷加宽、桥梁采用简支梁和可调式支座、河道截弯取直、涵洞选择沉降均匀处设置以及铁路沿线盐井口第四系土层注浆加固等方法,矿山工程处理措施主要有停采、盐井封闭、井身软弱破碎带注浆等方法。

Northeast freight railways around the Guangzhou hub was designed to pass through a mine field explored by solution mining, where large areas of goaf filled with brine had formed. To control the engineering risks for the railways, treatment measures had to be formulated on the basis of the current ground subsidence and the prediction of subsidence after terminal mining. The natural neighbor method was used to get the current subsidence contour, which indicated there had been two subsidence centers in the mine filed by March 2015, with accumulative subsidence of 1 m respectively. Numerical simulation was carried out to predict the terminal subsidence in the assumption that the salt ores were fully mined, and the results showed that the largest value of subsidence would be 2.4 meters. Based on the analysis and simulation, engineering treatment measures for railways passing through the mine filed were formulated, including widening the subgrade, adoption of simply supported beams and adjustable bearings for bridges, “the bends of the cut-off” of the river in the mine filed, culverts set on the uniform area and grouting reinforcement of Quaternary soil around salt wells. For the mine, measures such as ceasing mining, closing the salt wells and grouting reinforcement of fracture zone around salt wells, could be taken.