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Collapse and Water Inflow Characteristics of a Tunnel in Metamorphic Schist in the Nappe Structure Region
(1 School of Resource and Civil Engineering, Wuhan Institute of Technology, Wuhan 430073; 2 Faculty of Engineering, China University of Geosciences, Wuhan 430074)
Abstract Collapse and water inflow often occurs in regions with unfavorable geological conditions, and it is necessary to study this mechanism from a geological point of view. Taking the collapse and water inflow event in the Tongsheng Tunnel of the Shiyan-Fangxian Highway as an example, the development process of the disaster is analyzed and the typical phase characteristics of the deformation,collapse, water inflow and mud bursting in the surrounding rock are summarized. Based on the geological condition analysis, the geologi? cal survey for inside the tunnel and on the ground surface, and the TRT detection, the mechanism of tunnel collapse and water inflow is discussed from the perspectives of engineering geology and hydrogeology. The following conclusions are reached: 1) the tunnel passes through the compressive fault fracture zone, which is composed of broken rock and clay containing water, and it directly leads to the occurrence of collapse, water inflow, and mud bursts after tunnel excavation; 2) the nappe structure causes layering and fracturing in the surrounding rock; 3) with a high content of clay minerals in the schist, mud is easily created when water is encountered; and 4) the fault fracture zone contains confined groundwater. Finally suggestions for strengthening geological predictions and geological analyses are proposed.
Abstract：
Collapse and water inflow often occurs in regions with unfavorable geological conditions, and it is necessary to study this mechanism from a geological point of view. Taking the collapse and water inflow event in the Tongsheng Tunnel of the Shiyan-Fangxian Highway as an example, the development process of the disaster is analyzed and the typical phase characteristics of the deformation,collapse, water inflow and mud bursting in the surrounding rock are summarized. Based on the geological condition analysis, the geologi? cal survey for inside the tunnel and on the ground surface, and the TRT detection, the mechanism of tunnel collapse and water inflow is discussed from the perspectives of engineering geology and hydrogeology. The following conclusions are reached: 1) the tunnel passes through the compressive fault fracture zone, which is composed of broken rock and clay containing water, and it directly leads to the occurrence of collapse, water inflow, and mud bursts after tunnel excavation; 2) the nappe structure causes layering and fracturing in the surrounding rock; 3) with a high content of clay minerals in the schist, mud is easily created when water is encountered; and 4) the fault fracture zone contains confined groundwater. Finally suggestions for strengthening geological predictions and geological analyses are proposed.
.Collapse and Water Inflow Characteristics of a Tunnel in Metamorphic Schist in the Nappe Structure Region[J] MODERN TUNNELLING TECHNOLOGY, 2017,V54(6): 38-44
2017, Vol. 54 