下穿岩溶天坑隧道暴雨期涌水量峰值估算方法

Estimation method of water inrush peak value in tunnels penetrating karst sinkhole during rainstorm periods

岩溶地区隧道建设不可避免会遭遇涌水灾害,突涌水量估算是岩溶隧道施工抢险与后期处治方案制定的重要基础。天坑洼地是岩溶地区特殊地貌单元,是联接岩溶地区地表水与地下水的重要通道,下穿岩溶天坑隧道涌水量不仅受岩溶区水文地质条件控制,而且还受到暴雨期岩溶天坑小流域地表径流补给的影响。结合实测数据和统计数据,基于小流域暴雨资料推求地表汇流洪峰形成机制,提出了一种考虑岩溶天坑流域地表径流补给的下穿岩溶天坑隧道暴雨期突涌水量峰值估算方法,并结合鸡冠山隧道的隧址区地形地貌、水文地质条件与实测涌水资料,开展了案例分析计算与实测涌水量对比。结果表明:传统涌水预测方法无法考虑暗河与地表水补给的影响,与实测结果差距很大,本方法能够准确预测隧道下穿岩溶天坑区暴雨期突涌水量峰值,为保障岩溶区隧道施工与运营安全提供重要支撑。

Tunnel construction in karst area will inevitably encounter water inrush disaster.Estimation of water inrush volume is an important basis for emergency rescue and later treatment plan formulation of karst tunnel construction.Sinkhole depression is a special geomorphological unit in karst areas,which is an important channel linking surface water and groundwater in karst areas.The amount of water inrush in tunnels penetrating karst sinkhole is not only controlled by hydrogeology of the karst area,but also influenced by surface runoff recharge of karst sinkhole sub-basin during rainstorm periods.Based on the measured data and statistical data,the formation mechanism of surface confluence flood peak is deduced based on the rainstorm data of small watershed,and a method for estimating water inrush peak value in tunnels penetrating karst sinkhole during rainstorm periods considering the surface runoff recharge is proposed.Combined with the topography,hydrogeology and measured water inrush data of a tunnel site area of Jiguanshan Tunnel,the case analysis calculation and the comparison with measured water inrush are carried out.The results show that the traditional water inrush prediction method cannot consider the influence of underground river and surface water supply,and its prediction results has a large gap with the measured results.This method can accurately predict the water inrush peak value in tunnels penetrating karst sinkhole during rainstorm periods,which provides important support ensuring the safety of tunnel construction and operation in karst areas.