隧道排水系统结晶堵塞机理及防治措施初探

On Mechanism of Crystal Blockage of Tunnel Drainage System and Preventive Countermeasures

隧道排水管结晶堵塞给隧道施工及运营带来了极大的困扰。文章通过现场调研和文献调研方式,对隧道排水管结晶堵塞机理进行分析,并提出工程防治建议。主要结论为:隧道排水管结晶具有区段性,在建隧道中NaHCO3型地下水结晶现象严重,结晶体成分为CaCO3,初期支护、排水管流出溶液pH、碱度很高;一般情况下,水流流速越小,结晶量越大;隧道排水管结晶堵塞可以分为地下水与喷射混凝土化学反应、地下水对混凝土的侵蚀、排水管溶液中析出晶体和沉积堵塞四个过程,实际工程中可能同时发生,并相互影响;隧道排水管结晶堵塞主要影响因素为地下水类型、喷射混凝土特性、排水管溶液析晶的物理化学条件和排水管沉积条件;最后从防排水设计、施工控制两个角度提出了工程防治建议。

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 block⁃age of tunnel drainage pipe,and puts forward prevention suggestions.The main conclusions are as follows:The crys⁃tallization 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 simultaneous⁃ly and interact with each other.The main factors affecting the crystallization and blockage of tunnel drainage pipe in⁃clude the type of groundwater,the characteristics of shotcrete,the physical and chemical conditions of crystalliza⁃tion of drainage solution and the deposition condition of drainage pipe.Finally corresponding engineering sugges⁃tions are proposed from two perspectives of waterproof and drainage design and construction control.