Abstract:

Defects, such as cracks, spalling, falling and water seepage, occurred to the lining of the coal measure section of Jiazhuqing tunnel in 2003 and 2013 respectively. In the paper, the characteristics of and causes for the defects of the tunnel are investigated and analyzed. Conclusions drawn and advices proposed are as follows: 1) The transition section between the large deformation controlled section and the large deformation uncontrolled section is the main defect section, with the lining cracks as the main defect; 2) The ground stress in the tunnel region develops, concentrates and increases continuously, with the section at the smallmileage side of the serious deformation section as the main ground stress concentration and action section; 3) The ground stress is the main cause for the tunnel defects, with the weak surrounding rock and the weak tunnel structure as the secondary causes for the tunnel defects; 4) The tunnel defects in the coal measure section caused by the concentration and action of the ground stress are expected to have a 6~10 year cyclic period; 5) It is suggested that the scope of the strengthening of the weak rock section in similar geological conditions should be extended.

Key words: Jiazhuqing tunnel, coal measure, high ground stress, defect, characteristics, cause analysis