Model Test Study On Micropiles In Landslide Reinforcement

Micropiles have been used in landslide reinforcement more and more recently because of the merit that little machinery, adaptability to stratum, rapid constructing speed, low influence to the landslide. But due to its short application time, people have no enough understand to the characteristic of micropiles in landslide reinforcement. Relying on the China Geological Survey item"Large scale model text on micropiles in landslide reinforcement", the paper studies the characteristic of single micropile, micropiles in low, micropile groups with different reinforcement arrangement in landslide reinforcement. The main results of research as follows:(1) The landslide push force effecting on micropiles is distributed as triangle. The focus of resultant force approaches to the sliding face as the the stability coefficient of the landslide debases. The focus of resultant force lies in 1/3 pile length up the sliding face when the landslide slides. The landslide resistance behind the micropiles is distributed as parabola. The landslide bedding resistance is different along the depth and that near the sliding face is bigger.(2) Each micropile in micropile groups effects force and deforms at the same time. The landslide push force effecting on each micropile reduces by 15 percent along the sliding direction. The landslide push force effecting on the last micropile is only one of third of that effecting on the first micropile.(3) The damage form of micropiles with different reinforcement is different. The damage form of micropiles with center reinforcement arrangement is bending failure near the sliding face. The damage form of micropiles with surrounding reinforcement arrangement is cutting and bending failure in the sliding face. The damage form of ecch micropile in cluster is same.(4) The pile body above the sliding face effects negative bending moment but the scale is different in single micropile and micropiles in cluster. The bending moment in single micropile lies in ten pile diameters above the sliding face while that in micropile groups lies in the whole pile body above the sliding face. The biggest negative bending moment lies on seven pile diameters above the sliding face. The pile body that in the scale of ten pile diameters down the sliding face effects positive bending moment and the biggest of that lies on five pile diameters down the sliding face.(5) The shearing force of each micropile in pile cluster is same on the whole. The shearing force in the area from seven pile diameters down the sliding face to seven pile diameters above the sliding face has the same direction with the sliding. The biggest shearing force lies on the sliding face. The shearing force in the area from seven pile diameters to twenty-three pile diameters down the sliding face and from seven pile diameters to twenty pile diameters above the sliding face has the negative direction with the sliding. The biggest negative shearing force lies on thirteen pile diameters above the sliding face and twelve pile diameters down the sliding face.(6) Micropiles still have skid-resisting capacity when failure. But the skid-resisting mechanism is different. Before failure the shear-bearing capacity and bending resistance of micropiles effects while failure the pulling resistance of the steel effect.