Abstract: Micropile is superior to conventional retaining structures in the emergency treatment of landslide, embankment slope, or foundation pit with poor stability. Since the bearing capacity and failure characteristics of different micropiles vary, we improved the yas-2000 compression testing machine and applied it to measuring the flexural bearing capacity of three different micropiles: reinforced concrete pile, steel pipe concrete filled rebar pile, and steel pipe concrete filled I-beam pile. Results unveiled that the whole process of force acting on reinforced concrete pile can be divided according to three phases, namely, uncracked phase, cracked phase, and destruction phase. The stress process of steel pipe concrete filled rebar pile, and steel pipe concrete filled I-beam pile can be divided into four phases, compaction phase, elastic phase, elasto-plastic phase, and reinforcement phase. In addition, comparison of the load-displacement curves of these three micropiles revealed that given the same diameter, steel pipe concrete filled I-beam pile has the largest flexural bearing capacity with the ultimate bending moment reaching 209.21 kN·m.

Key words: micropiles, flexural capacity, reinforced concrete pile, steel pipe concrete filled rebar pile, steel pipe concrete filled I-beam piles