ABSTRACT:

Bolt and wall rock should be regarded as a whole in the tunnel stability analysis. Based on the principle of bolt-rock combined action, a monitoring system of bolt stress and wall rock strain was developed, and a judging standard for the warning level of the rock stability was put forward, including the rock movement, rock moving velocity, rock moving acceleration, and the stress variation rate of bolt. The method was used in the PanGuShan mine, and an early-warning was made for some dangerous area. Based on the data acquisition of stress and strain of bolt, the system realized online monitoring by underground wireless transmission, it would be useful for the prevention of ground pressure disaster.

1 INTRODUCTION

Pangushan Bismuth & Tungsten Mine is the only production site of Pangushan Jiangxi Tungsten Industry Co., Ltd. The Mine is located 33 kilometers south of the city of Yudu County, Jiangxi Province, and it's under the administrative jurisdiction of Pangushan Town in Yudu County of Jiangxi. Composed by three sets of veins, the mine is developed with joints, and there are seven groups of distributed faults. In June 1966 and July 1967, destructive activities of ground pressure occurred in the upper part of the mine, causing serious losses. After it was converted to deep mining since the 1990s, ground pressure activities occurred frequently, and in the mid-sections of 535 m-485 m and 485 m-335 m, the active blocks in vertical goaf are big enough to pose serious threats.

Based on the above, anchorage supports were adopted to places that may affect the stability of rocks in Pangushan tungsten mine, reinforced by security rock pillars and other methods. At the same time, the ground pressure of key areas was monitored through sophisticated methods. By analyzing the monitoring data of Pangushan tungsten mine, a complete set of system for monitoring and warning ground pressure has been developed and it is of great significance for preventing harms caused by ground pressure.

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