Abstract: Aiming at the floor heave problem of thick and hard floor of large chamber in deep mines the winch room in Tangkou Mine about a kilometer in depth is taken as an engineering case, and the damage mechanism of thick and hard floor is studied. In early excavation, the floor sustains obvious layered damage by buckling and then slides and moves along damage fracture surface under the action of high ground stress. The critical load for damage by buckling is derived based on buckling theory of thin plate. For controlling the damage by buckling of floor, based on the principle of strength and control of the whole floor, the technology of composite piles and foundation of thick and hard floor in large chamber is proposed as follows: based on inverted arch and combined transverse steel beams and chained double reinforcing meshes, concrete is poured to form strong foundation beam so as to balance the force and prevent stress concentration of floor. The combined anchor wires and high-pressure grouting are used to form composite piles to block the floor stress to transfer from the surrounding rock and to balance the stress. Finally composite piles and foundation are formed, and the efficiency of engineering application is satisfactory. The research may be helpful to controlling large chambers in deep mines and large underground spaces.