一种典型的岩溶隧道衬砌压裂突水灾害成因与防治

CAUSE,DISASTER PREVENTION AND CONTROLLING OF A TYPICAL KIND OF WATER INRUSH AND LINING FRACTURING IN KARST TUNNELS

通过季家坡隧道衬砌压裂突水工程实例分析,研究隧址区岩溶发育特征,提出高陡倾充填型岩溶裂隙蓄水构造形式,分析其形态、充填物性质和致灾机制;采用裂隙封堵、周壁注浆、排水泄压、结构置换、信息化注浆效果评估的水害处治措施治理隧道衬砌压裂突水。高陡倾充填型岩溶裂隙蓄水构造呈高角度裂缝状产出,降雨后,极易在其裂隙空间内积水形成高水压;此外,由于其通透性较差,沉积物运移速度慢,易于在其底部堆积,在自重应力和高水压压实作用下,充填介质沉积、胶结成坚硬与半坚硬状,透水性较差,开挖揭露初期,不出水或仅少量涌水,易于被忽视;但揭露后一段时间,裂隙内充填介质不断流失,最终导致充填物产生管涌、流土或被整体挤出,进而将上方暗河水、溶腔水或地表水等导入隧道,造成衬砌压裂、隧道突水等灾害。研究成果不仅成功应用于季家坡隧道突水灾害处治,对于避免类似突水事故的发生和灾害防治亦有较强的借鉴意义。

By analyzing the project example of Jijiapo tunnel s lining fracturing,studies were done on the karst developing characteristics of the tunnel district,and a kind of water bearing structures,steeply inclined and filling type of karst fissure,was probed.Its configuration,filling s characteristics and disaster-causing mechanisms were studied.Measurements,as fissure-blocking,perinous grouting,discharge of water and release of pressure,substitution of structures,as well as information grouting assessment methods,were taken to govern water inrush-lining fracturing in tunnels.Steeply inclined and filling type of karst fissure-water bearing structure occurred in a steeply inclined angle of fissure,easily accumulate water and form a high water pressure in its fissure space.In addition,sediments easily accumulate at the bottom for its slow migration in a fissure.Because of dead weight stress and high water pressure compaction,the filling medium changes to poorly permeable,hard or semi-hard sedimentation and cementation.It is often neglected when excavated and revealed for there is no or a litter of water inflow.However,after a period of time s excavation,the filling medium of the fissure is washed out gradually by water and will finally lead to piping,soil flow or entirely extrusion out;and then import underground,cavern or surface water into the tunnel,causing disasters of lining fracturing,water inrush and so on.Research results are not only used for the controlling of water inrush in Jijiapo Tunnel,but also have strong reference value for avoiding and controlling similar disasters.