MODEL TEST ON MECHANICAL BEHAVIOR OF H-TYPE ANTI-SLIDE PILE UNDER CURVED LANDSLIDE

Based on a large highway landslide management project, six groups of model tests were performed using a newly designed device. In these tests, same slip surface and pile anchorage depth but different coupling beam length and back pile cantilever length (coupling beam height) were set. Pile mechanical behaviors (including the pile top displacement, pile bending moment and soil pressure distribution) changing disciplines and mechanisms were studied. Furthermore, the general expression capable of describing the parabolic distribution of post-pile landslide thrust was proposed. The experimental results indicate that the horizontal displacement of the h-type pile top could be divided into three stages. The positive and negative distribution of pile bending moment alternatively appears. The pile top horizontal displacement and the bending moment of the back pile are significantly larger than those of the front pile. With a reduction in the back pile cantilever height, the pile moment distribution shows minor changes. However, in this process the front pile gains a significant increment in pile top horizontal displacement and pile moment while the back pile suffers a dramatic reduction. The length variation of the coupling beam significantly affects the load transfer and synergistic force characteristics between the front and back piles, resulting in changes in the horizontal deformation and bending moment. The extreme values of both positive and negative bending moments are located at the end of the coupling beam. Compared with the length of the coupling beam, the size and distribution of the bending moments of the coupling beam are more obviously influenced by the cantilever length of the back pile. With the decrease of the coupling beam length or the increase of the back pile cantilever length, the soil pressure behind the back pile shows a parabolic type, a parabolic type with a lower gravity center, or an approximate trapezoid type distribution. In addition, the proposed expression could well characterize the parabolic distribution of the landslide thrust. By adjusting the parameters describing the position of the joint force action point, the approximate trapezoidal type distribution of the landslide thrust could be described as well.