PROPORTION OPTIMIZATION DESIGN OF STEEL FIBER REINFORCED CONCRETE MIX FOR TUNNEL SEGMENTS

Shield tunnel construction has entered a period of rapid development in China. At present, shield method with reinforced concrete segments is still the main support form of shield tunnel, but ordinary reinforced concrete segments are thick, heavy, and easy to be damaged and cracked under fabrication, transportation and construction. Through proportion optimization design of steel fiber reinforced concrete mix, it was concluded that the compressive strength of concrete by the secondary synthesis method and equal-volume coarse aggregate replacement instead of steel fiber method was 17.7% and 13.1% higher than that of ordinary concrete, and the splitting strength by both of the methods was 54.2% and 51.1% higher than that of ordinary concrete, respectively. From the aspect of material consumption, the cementitious material consumption could be reduced 25.9% by the equal-volume coarse aggregate replacement method than the secondary synthesis method, and the cost control of steel fiber concrete was more reasonable, which was a relatively economical design method of steel fiber concrete.