Abstract:

Youshui tunnel is located on XiHan expressway in Shaanxi province. Large deformation occurs at many places in this tunnel. The monitoring data shows that the deformation is rapid and lasts long duration. Against this background, evaluation is made on the effectiveness of several typical emergency countermeasures such as grouting, temporary invert and systematic rockbolts, by means of analyzing on the mechanisms, making numerical simulations by FLAC3D, monitoring and drawing lessons from the construction. The following conclusions are drawn: 1) the theoretical calculations show that the consolidation effect of grouting is significant and the effect of temporary inverts is better than  that of grouting; 2) the monitoring data shows that the effect of grouting is discrete, the effect of temporary inverts is the best and the conventional mortargrouted rockbolts have almost no consolidation effect. In the end, relatively costeffective emergency countermeasures to control the large deformation of the surrounding rock mass are recommended.

Key words: surrounding rock mass, large deformation, FLAC3D, grouting, temporary invert, systematic rockbolt, emergency countermeasure, effectiveness evaluation