How to handle chimeny formaion(cavity) at crown top, in frible shale formation, and highly water seepage ?

Profile of the tunnel should be closed with steel arches with steel plates in place of the chimney from which the water comes. Behind the steel plates should be installed pipes for drainage and carry them to the feet of the tunnel where it will be connected to the drainage system of tunnels. Through the steel plates in the roofis necessary to set two pipes for pumping concrete over them. After that, on steel arches set netting and close the profile with shotcrete. By closing the profile of shotcrete through tubes placed in the roof of the tunnel in the chimney can be pumped concrete plug. Before the above procedure is necessary if the tunnel until then broken through the full profile import earthen or stone material and reduce the profile of tunneling approximately in half. Care should be taken during pumping concrete plug in the chimney, the concrete will not closed  drainage tubes