引大入秦工程盘道岭隧洞病害原因浅析

盘道岭隧洞是"引大入秦"灌溉工程总干渠上最长的无压引水隧洞,穿过大通河与庄浪河流域分水岭,随着第五个国家级新区—兰州新区的成立,引大入秦工程将承担为新区生产生活供水的任务,为重点控制工程.但是由于工程地质条件复杂,隧洞在建时和运营后出现多种病害问题,如地下水的侵蚀、渗漏水、衬砌裂缝等,多次维修仍不能控制.维修期间通过对地下水化学组成的分析,衬砌裂缝监测,裂缝渗漏水处白色沉淀物矿物成分分析,发现地下水具有化学和物理作用,衬砌侵蚀的式为溶出性和化学侵蚀,得到地下水对存在于衬砌中微观裂缝和微孔的发育起到促进作用,地下水是隧洞病害的重要因素,并且裂缝变化是时间效应的累积,盘道岭隧洞没有冻害形式的病害.

Study on the Possible Causes of Diseases of Pandaoling Tunnel in Datonghe-Qingwangchuan Diversion Proj ect

Pandaoling Tunnel is the longest free-flow diversion tunnel along the main canal of Datonghe-Qin-wangchuan Diversion Proj ect,which crosses the water divide of Datong River and Zhuanglang River.With the establishment of the fifth national new district-the New District of Lanzhou,Datonghe-Qinwangchuan Diversion Proj ect will undertake the water supply task for production and living of the new district,and it is the key proj ect.But because of the complicated engineering geological conditions,diseases like lining crack, water leakage and erosion of underground water occur during the construction and operation of the tunnel, which can not be controlled by several times of repairing.By the chemistry analysis of underground water taken from the tunnel,monitoring of cracks in lining and mineral analysis of white precipitation from cracks in lining,it is concluded that groundwater has chemical and physical effects,and the form of lining erosion is dissolution erosion and chemical attack.It is found that groundwater plays a promoting role for the develop-ment of micro-cracks and micro-voids in lining,groundwater is an important factor in tunnel diseases,and the changes of cracks may be resulted from the accumulations of time effect.There is no frost damage in the form of disease in Pandaoling Tunnel .