Abstract: In order to study the stress characteristics of micro-steel pipe pile-anchor support in soil-rock-bound stratum, as well as the internal force changes of steel tubular pile at different excavation depths and after the completion of anchor cable and anchor rod construction, a field test was carried out in a subway station in Qingdao. The foundation pit was strengthened by using the third-order micro-steel pipe pile combined with anchor cable and anchor rod, and the internal force test was carried out on two test piles in the first order of the foundation pit. The steel pipe piles in different excavation depth, anchor and anchor cable construction after the completion of the internal force of change. The results show that the bending moment near the excavation surface and the top of the pile is large, the measured bending moment value is up to more than 15 kN·m. The anchor cable lock can effectively suppress the development of bending moment. The law of the internal force changes in the pile body is obviously related to the earth rock geological conditions, and the maximum positive bending moment is 32.43 kN·m.  

Key words: micro-steel pipe pile, soil-rock-bound strata, mechanical characteristic, foundation pit, internal force, bending moment