Study on ventilation in tunnelling.

Abstract

The purpose of this study is to clarify the most suitable ventilation method for tunnelling around the face. The test-tunnel models were a 1/20-scale model for the air experiment and a 1/100-scale model for the water experiment. Flow patterns for both models were studied by flow visualization techniques. The velocity distribution and dust concentration of the 1/20-scale model were measured. First of all, the wind direction and air-speed in an actual tunnel and in a 1/20-scale tunnel model were measured. Then, the flow similarity between the actual tunnel and the scale model was confirmed. After that, the velocity distribution and dust concentration were measured for the five different ventilation methods mentioned above. The tracer method was applied for the two-dimensional flow visualization by using laser light sheet, and the tuft grit method was applied for three-dimensional flow visualization. According to these results, it became clear that the most suitable ventilation method in tunnelling around the face was the air pumping type, setting the duct at side position and air exhausting type with lower local fan.