In the South-to-North Water Diversion Project

a large number of expansive soil slopes slid due to the long and gently inclined fissures. The micropiles had achieved good application in the rescue and reinforcement project of the expansive soil slopes. The study on the reinforcement mechanism and the influence of parameters of micropiles in reinforcing the soil slope with long and gently inclined fissures is of great significance for the design of such projects. Based on the actual project of reinforcing expansive soil slope with micropiles

the thrust was applied on the sliding body along the direction of the fissure surface

and the failure tests of the non-piled slope with different angles of the gently inclined fissure were carried out. After taking the pile length

row spacing and pile position as influence parameters

the model tests of micropile-reinforced soil slope with long and gently inclined fissures were carried out

the displacement characteristics of the slope and the stress characteristics and the reinforcement effect of the micropile were analyzed. The test results showed that the micropile had a good anti-slide reinforcement effect for the slope with gently inclined fissures

and could maintain the anti-slide resistance at a high level. The anti-slide resistance provided by micropiles increased with the increase of pile length (anchorage ratio)

while the increase efficiency decreased with the increase of pile length. It was suggested that the anchorage ratio of micropiles should be 0.5 when the pile is arranged at upper 1/3 position of the slope

and less than 0.65 when it is arranged at lower 1/3 position of the slope. The distribution of bending moment and shear force of the piles was reversed S-shape

and the maximum values were located near the fissure surface. The double-row piles can enhance the toughness of the slope to resist damage. When the row spacing was 200 mm (10 times the pile diameter)

the front and rear rows of piles can well coordinate

which could give full play to the anti-slide effect and greatly increased the anti-slide thrust of the slope.