Abstract: In view of the mechanism of floor heave, the stress and deformation behaviour of floor rock mass was studied and analyzed by numerical simulation in the situation of different stress concentration （continuous change of λ from 1 to 3）. The results showed that floor rock mass could be divided into three zones in horizontal direction. They were stress raising zone, stress reducing zone and initial stress zone. Under the condition of in-situ stress concentration increasing, the amount of floor heave, deformation of laneway’s side and peak stress concentration are significantly increased. According to the difference of floor surrounding rock deformation, expansive area, compressing expansive area and compressed area were devided. In the different depth along floor horizontal direction and vertical direction, there is elliptic zero deformation area of floor; the rock mass in this area produces stretching expansion and the rock mass outside the area is compressed.