干湿循环作用下充填岩溶区隧道安全性研究

Study on the Safety of Tunnel in Filling Karst Area under Dry-Wet Cycle

为探究干湿循环对充填岩溶区隧道运营安全的影响,首先,开展了不同干湿循环次数岩溶充填物直剪试验,分析抗剪强度指标的劣化规律,提出了劣化系数的预测公式,并对劣化机制进行分析。研究发现:干湿循环使充填物由致密状态变为松散状态,导致抗剪强度指标劣化,黏聚力的劣化程度大于内摩擦角,干季试样的劣化程度大于湿季。然后,采用FLAC3D软件对隧道全穿和顶穿溶洞两种工况运营10年内衬砌的变形和安全系数进行计算,结果表明:全穿溶洞工况各位置变形和安全系数呈大小交替循环的趋势,干季的变形较小,安全系数较大,拱脚拱顶为软弱位置;受完好围岩的影响,顶穿溶洞工况拱顶的变形一直增大,拱脚位置干季的安全系数小于湿季,拱顶为软弱位置,应进行加固处理。

In order to explore the impact of dry-wet cycles on the safety of tunnel filling in filling karst area, this paper first carried out direct shear tests of karst fillings with different numbers of dry-wet cycles to analyze the degradation laws of shear strength indicator, presented the prediction formula of deterioration coefficient, and analyzed the degradation mechanisms. The study found that the dry-wet cycle causes the filling to change from a dense state to a loose state, leading to deterioration of the shear strength index. The deterioration of the cohesive force is greater than the internal friction angle, and the deterioration of the dry season samples is greater than that of the wet season. Then, this paper uses FLAC3D software to calculate the deformation and safety factor of the lining of all and top of the tunnel located in karst caves for 10 years of operation. The results show that the deformation and safety factor of each position in all of the tunnel located in karst caves are in a trend of alternating large and small. The deformation in the dry season is small, the safety factor is large, and the arch foot and the bottom of the arch are weak. In the top of the tunnel located in karst caves working condition, the deformation of the vault has been increasing, the safety factor of the arch foot position in the dry season is smaller than that in the wet season, and the vault is a weak position and should be reinforced.