隧道二次衬砌质量问题分析与改进措施

Analysis and Improvement Measures of Tunnel Secondary Lining Quality Problems

针对河北省张家口市在建太子城—锡林浩特铁路太子城至崇礼段小断面隧道施工过程中的二次衬砌厚度不足、背后脱空、混凝土不密实等质量问题,对影响二次衬砌质量的六种因素进行了统计分析。结果显示,二次衬砌厚度不足主要因初期支护不平整引起,而导致初期支护不平整的重要原因是初期支护断面测量测点间距较大。据此提出采用三维激光扫描仪代替光电断面扫描仪测量初期支护断面,对欠挖部位精准凿除后复测,直至该断面无欠挖部位方可浇筑二次衬砌混凝土的改进措施。通过现场检测,采取措施后二次衬砌厚度合格率由78.0%提升至96.7%。

Based on the quality problems of insufficient secondary lining thickness,cavity behind lining,non-dense concrete during the construction of small cross-section tunnel from Taizicheng to Chongli of Taizicheng-Xilinhot railway in Zhangjiakou City,Hebei Province,six factors impacting on secondary lining quality were statistically analyzed. The results show that the insufficient thickness of secondary lining is mainly caused by the unevenness of the primary support,and the important reason leading to the unevenness of the primary support is the large distance between the measurement points for the primary support. Therefore,it is proposed to use 3D laser scanning instead of photoelectric cross-section scanner to measure the primary support cross-section,and re-measure the underbreak section after accurately cutting,and then pour secondary lining concrete until there is no underbreak section. Through on-site inspection,the qualified rate of secondary lining thickness increased from 78.0% to 96.7% after taking measures.