连拱隧道裂缝运动的监测与分析

Monitoring and analysis for movement of cracks of twin-arch tunnel

连拱隧道在修建以及运营过程中出现裂缝,会导致衬砌出现渗漏水,破坏结构的完整性、影响结构的耐久性,极端不利情况下甚至可能导致结构整体崩溃,危及隧道施工及运营的安全。开展裂缝运动特征的基础研究,进行大量现场监测并总结规律是可行的方法。典型连拱隧道30个裂缝测点的监测结果表明裂缝运动存在时效特征,先增后减的裂缝运动是一般规律,跳跃性突变及匀速单调发展的裂缝运动不是裂缝正常的运动范畴,必然是施工扰动或其他相关因素导致裂缝运动出现异常所致。裂缝的运动既有张开又有鼓出,通过多点张开及鼓出的联合测量,能够更好地了解裂缝运动的多点时空特征,可用于判定裂缝测点布置的代表性问题。双连拱隧道的施工工序远较分离式隧道复杂,通过裂缝运动的监测,可以了解隧道结构整体受力的健康情况,进而指导隧道的施工及防灾。

Cracks of twin-arch tunnel in construction or in operation would cause leakage of lining, damage of structure and reduction of tunnel durability. Under extreme adverse conditions, tunnel structure might even be collapsed completely. It is essential to conduct basic study on crack movement for twin-arch tunnels, and in-situ monitoring is one of the feasible methods. The monitoring data of 30 cracks＇ movements in a typical twin-arch tunnel of the Yuanjiang-Mohei expressway in Yunnan province indicated that the width of cracks changed with time, with the general trend of increasing first and decreasing later, and any sudden change or monotonic increase in crack width is abnormal and must be caused by external disturbances. The crack movement for the twin-arch tunnel involves both opening and extruding, the time-dependent characteristics of which can be obtained by monitoring. For twin-arch tunnels, the construction course is more complicated than two separate tunnels, and crack monitoring may provide an efficient way to determine the health conditions of a tunnel.