Abstract: With the rapid development of underground engineering,the construction scale of tunnels and roadways in Chi na is constantly expanding.The excavation depth has been increasing,which leads to the engineering support facing a more complex environment with high stress,extremely soft rock,strong mining,etc.As a commonly used form of reinforcing support in soft rock roadways and tunnels,the high bearing capacity of steel supports will directly and effectively control the deformation of the surrounding rock.Firstly,this paper summarized the form and mechanism of several common steel supports,such as sec tion steel support,grille steel frame and concrete-filled steel tubular support.Then,the current research status of steel support bearing capacity is analyzed and sorted out from theoretical calculations,mechanical tests and numerical simulations,respec tively.The study results show that:① U steel support can effectively play the key to the bearing capacity is the connection abil ity of the clamp.Under the premise of smooth and effective slippage of the clamp joints,the higher the preload on the clamp, the more favorable the bearing capacity of the support.② I-beam support bending and torsion resistance is weak,and prone to destabilization.Therefore,the support should be designed and selected to meet the requirements of bearing capacity as well as to ensure stability.③ Grid steel frame can be optimized by reducing the diameter of the main reinforcement and web reinforce ment on the rock side.Replacing the main reinforcement with steel tubes and high-strength steel bars can increase the bearing capacity of the grille members.In addition,the actual research and application should also focus on the setting of its nodes. ④ The bearing capacity of steel pipe concrete support is 2~5 times higher than that of traditional section steel support.The load carrying capacity of the member is closely related to the wall thickness of the steel pipe,the strength of the concrete and the strength of bending reinforced round steel.On the basis of the above analysis,the future research direction of steel support is prospected from the theoretical calculation,mechanical test and field application. It is believed that the future research should be focused on further refining and perfecting the steel support bearing capacity test,establishing the accurate design method of the steel support bearing capacity,exploring the interaction mechanism between the steel support and the surrounding rock,and developing a new type of support system.

Key words: tunnel,roadway,steel support,bearing capacity,support