Experimental Load Transfer of Piles Subject to Lateral Soil Movement

Remediation of slope failures requires stabilization alternatives that address causes of slope instability. Slope reinforcement and pile stabilization systems, if properly designed, are effective in preventing slope movements in weak soils. Soil load transfer to pile elements from the lateral soil movement as occurs in slope failures is a complex soil-structure interaction problem, and the significant differences in existing design procedures of pile stabilization suggest that the stabilizing mechanisms are not fully understood. The downslope soil movement of slope failures induces unique, unknown lateral load distributions along stabilizing piles. The reliable estimation of these load distributions is important, because the influence of piles on the global stability of the slope depends directly on the pile loading condition. Soil-structure interactions for small-diameter piles subject to lateral soil movement were investigated by conducting full-scale pile load tests, in which piles installed through a shear box were indirectly loaded by uniform lateral translation of soil. Instrumentation of the shear boxes and pile reinforcement indicated the load distributions that developed along the piles. The load test analyses which succeeded the pile load tests support the claim that the distributed loads which are achieved during pile loading vary linearly with depth. The product of the analysis, which answers a central question of the research, is directly incorporated into the proposed design methodology for soil displacement grouted micropiles. It is apparent from the pile load tests that small-diameter pile elements provide effective passive resistance to lateral soil movement. The proposed, non-proprietary remediation technology, if implemented into current slope remediation practices, offers an alternative that gives consideration to cost constraints, schedule constraints, and constructability concerns of local transportation agencies.