Abstract:

The diameterdepth ratio of ventilation vertical shaft of Guantian Tunnel on ZhangzhouYongan Expressway in Fujian is small. As a result, the conventional raiseboring method is improved; the conventional drill bit of raiseboring drill is replaced by air DTH hammer; and then the pressurereducetyped boring mode is adopted. The gradient of guiding hole is reduced; the drill bit abrasion is reduced; rapid construction of vertical shaft is achieved; and a series of raiseboring methods (with diameterdepth ratio less then 1.3%) for hardrock deep vertical shaft is obtained. Meanwhile, the horizontal pressure of surrounding rock of hardrock deep vertical shaft is measured by means of automatic monitoring technology and wireless transmission technology. The measured results (0.01-0.03 MPa) are 24%-46% of the values in related criteria and are independent of depth. The authors suggest that the surrounding rock pressure should be further improved.

Key words: tunnel, hard rock, deep vertical shaft, improved raiseboring technology, air DTH hammer, diameterdepth ratio, automatic monitoring, wireless transmission technology, surrounding rock pressure