The Remodeling of Mining and Safty Structure of Akabira Colliery.

Akabira Colliery has been opend since 1938. The mine has many minable coal seams and is recentry extracting six seams, of them. The seams incline steeply toward syncline axis which runs across the central part of the mine from south to north. The mine has continued to product annualy washing coal from 1Mt to 2Mt since 1960's on a condition that there were mining trouble and safty caused by many faults and a lot of methane gas flow.In 1986, a change of coal situation that a demand of domestic coal took a sudden turn for the decrease because on an amendment of coal policy in Japan made Akabira Colliery determine to improve the basic structure of mining and safty. As the result, the structure of ventilation and transportation was simplified and made more efficient. And mining inside the shaft saftypillar has become a necessity. Heavy mechanised mining system replaced manual one. Akabira Colliery has become a new mine and come to be able to continue production in spite of severe situiation of domestic coal. Since the shaft is apt to be influenced or possibly damaged by ground movements, the prediction of shaft behavior due to mining, the monitoring of shaft deformations, and the repair of shaft damage should be executed as precisely as possible.This report shows experience of a drastic remodeling of mining structure and safty one which was carried out at Akabira Colliery from 1986 to 1994.