Abstract: When ordinary concrete-filled steel tubular supports (CFST supports) are used in extremely soft rock roadway, they are likely to be destroyed before the core concrete forms a larger strength. To solve this problem, the mixing experiment of early strength concrete has been carried out at first and then researchers have developed the early strength CFST supports based on previous experimental results. Further more, early supporting counter-force of early strength CFST supports and ordinary CFST supports have been contrastively analyzed by using theoretical calculation. At last, composite supports scheme based on early strength CFST supports has been designed and simulated with Beizao mine roof roadway as the engineering background, which has been used in engineering practice ultimately. Research results have indicated that the initial slump surpasses 220 mm, and the retarding time surpasses 3 h, and its 1 d compressive strength after final set surpasses 40 MPa, and that 3 d compressive strength surpasses 49.9 MPa,which have met pumping and early strength requirements; the 1 d，3 d and 7 d supporting counter-force of early strength CFST supports are 1.68 times,1.4 times and 1.26 times of the ordinary CFST supports, and it can still grow slowly in the late stage; numerical simulation and engineering application have sufficiently proved that the composite supports based on early strength CFST supports can effectively inhibit the convergence deformation of the extremely soft rock roadway in the early time and ensure the long-term stability of the roadway.

Key words: concrete-filled steel tubular supports (CFST supports), extremely soft rock roadway, early strength concrete, mix proportion, composite support