The Study On The Characteristic Of Storing Space Of Water In Nibashan Tunnel

The water-gushing disaster is the most frequent geologic hazard in the construction and the management of the tunnel.The characteristics of water-bearing spaces is important factors for the position and inflow of water for water-gushing disaster. Based on the research of Nibashan tunnel, the water-bearing spaces of volcanic rock is analyzed in this article.According to the formation characteristics of volcanic rock, the lithology and lithofacies are analyzed firstly.Different types of volcanic rock has different performance of storing water,such as volcanic lava,pyroclastic rock and intrusive rock.And different lithofacies developed different primary void of storing water. Through the field investigation and core data, the distribution and assemblage of all kinds of volcanic rock and characteristics of lithofacies are analyzed.The water-bearing spaces in tunnel site include pore and fissure, then analyzing the types of them. Through the dip, joint opening,filling condition and fissure surface features,the development of fissure is statistically analyzed.Tectonic movement is the important influencing factor,then studying on the relationship between it and water-bearing spaces,based on anticline and faults.Based on permeability coefficient, the performance of storing water and the influence factors of it are discussed, including the angle of the crack and the relationship between lithology and fissure even the character of dike and the diagenesis.The groundwater level is discussed according to the data of drilling and geophysical logging. Then dividing the tunnel into two units of water-bearing spaces and the division of water storage structures and water-bearing zone are discussed by the conditions of topography and geomorphology, lithology and lithofacies, structure and chemistry test of water.At last, the spaces of water-bearing is classified into four grade based on the scale and hydrogeology conditions of the spaces. The water storage of four regional in the tunnel is analyzed. We draw a conclusion that the spaces in exit end of the tunnel are very developed and the amount of water stored is huge.