Abstract Crystal blockage in tunnel drainage pipe brings much trouble to tunnel construction and operation.
Through field investigation and literature research, this paper analyzes the mechanism of crystallization and blockage of tunnel drainage pipe, and puts forward prevention suggestions. The main conclusions are as follows: The crystallization of tunnel drainage pipe is segmental, the crystallization of NaHCO3 underground water is serious in the tunnel under construction, the crystal composition is CaCO3, the pH and alkalinity of the solution flowing out of the primary support and drainage pipe are very high. In general, the lower the water flow rate, the greater the amount of crystallization. The crystallization and blockage of tunnel drainage pipe can be divided into four processes, i. e. chemical reaction between groundwater and shotcrete, concrete erosion by groundwater, crystal precipitation in drainage pipe solution and deposition blockage. In practical engineering, the four processes may occur simultaneously and interact with each other. The main factors affecting the crystallization and blockage of tunnel drainage pipe include the type of groundwater, the characteristics of shotcrete, the physical and chemical conditions of crystallization of drainage solution and the deposition condition of drainage pipe. Finally corresponding engineering suggestions are proposed from two perspectives of waterproof and drainage design and construction control.
Abstract：
Crystal blockage in tunnel drainage pipe brings much trouble to tunnel construction and operation.
Through field investigation and literature research, this paper analyzes the mechanism of crystallization and blockage of tunnel drainage pipe, and puts forward prevention suggestions. The main conclusions are as follows: The crystallization of tunnel drainage pipe is segmental, the crystallization of NaHCO3 underground water is serious in the tunnel under construction, the crystal composition is CaCO3, the pH and alkalinity of the solution flowing out of the primary support and drainage pipe are very high. In general, the lower the water flow rate, the greater the amount of crystallization. The crystallization and blockage of tunnel drainage pipe can be divided into four processes, i. e. chemical reaction between groundwater and shotcrete, concrete erosion by groundwater, crystal precipitation in drainage pipe solution and deposition blockage. In practical engineering, the four processes may occur simultaneously and interact with each other. The main factors affecting the crystallization and blockage of tunnel drainage pipe include the type of groundwater, the characteristics of shotcrete, the physical and chemical conditions of crystallization of drainage solution and the deposition condition of drainage pipe. Finally corresponding engineering suggestions are proposed from two perspectives of waterproof and drainage design and construction control.
TIAN Chongming1 YE Fei1 SONG Guifeng2 WANG Qinglong2 ZHAO Meng1
.On Mechanism of Crystal Blockage of Tunnel Drainage System and Preventive Countermeasures[J] MODERN TUNNELLING TECHNOLOGY, 2020,V57(5): 66-76
2020, Vol. 57 