EVALUATION OF STABILITY OF UNDERGROUND OPENINGS BY USING MICRO-COMPUTERS

This paper deals with a method of monitoring the stability of underground openings during the construction. The method is based on the interpretation of displacements measured in the field. The strain evaluated from measured displacements is compared with the critical strain of materials. If the occurring strain is still smaller than the critical strain, the stability of openings is guaranteed. Normalized initial stress is used for determining the strain distributions around the openings. Back analysis plays an important role for obtaining the normalized initial stress from measured displacements. In order to make a quick interpretation of field measurements, microcomputers are generally placed at construction site so that the back analysis can be performed right after taking measurements.In this paper, the mathematical formulation of the back analysis for the use of microcomputers is shown together with some results of case studies.