In-Situ Study on the Combined Strengthening Effects of Intensive Micropile Groups and Anchor-Cable Ground Beam on Subgrade Slopes of Existing Roads

This paper studied the reinforcement effect on reinforced accumulation slopes from intensive micropile groups and anchor cable ground beams as well as the stress characteristics of micropile groups via in-situ monitoring. Data on pile lateral soil pressure; pile bending stress, anchor cable pre-stress, and displacement of deep holes in the slope was collected during the tests. Analysis was conducted on distribution characteristics of slope movement, micropile stress, and pile lateral soil pressure. Anchor cable reinforcement effects were evaluated based on the laws of long-term pre-stress loss and typical position-displacement curves. Results show the slope stabilization is mainly due to overall shallow layer sliding, so pre-stress loss and slope deformation rate exhibited converging trends after the completion of the light comprehensive treatment measures. During spring and the rain seasons, the bending stresses on the shallow portion of a micropile that is in the sides or middle of a river, changes from tensile stress to compressive stress; the stress value fluctuation at the deeper parts of the micropile is smaller. The lateral soil pressures are consistent throughout each pile row in a micropile group, reflecting the overall sliding resistance mechanism of micropile groups. Research results provide significant insight for future design of similar slope reinforcement engineering programs.