Lateral Load Tests on Small-Diameter Piles for Slope Remediation

Slope reinforcement and the use of structural pile elements can be an effective slope remediation alternative when conventional remediation practices (e.g., improved drainage) fail to consider the causal factors leading to slope instability (e.g., strength loss due to weathering). An experimental research program was aimed at developing a rapid, cost-effective, and simple remediation system that can be implemented into slope stabilization practices for relatively shallow (< 5 m) slope failure conditions. The non-proprietary remediation technology consists of small-diameter, grouted micropiles. The research program described in this paper establishes the micropiles as a feasible remediation alternative. Details of the experimental testing and the results from selected measurements are presented in the paper. Lateral load tests on drilled and grouted pile elements of two diameters, in which the piles were installed through a shear box and loaded by uniform lateral translation of soil, advanced our understanding of the soil load transfer to the piles. The pile load test plan included three soil types, and the piles were installed into glacial soils of the experimentation site. Instrumentation of the shear boxes and pile reinforcement indicated the load distributions that developed along the piles and the pile response to the physicallyimposed boundary conditions. Results show that piles installed in failing slopes will arrest or slow the rate of slope movement. Furthermore, the soil movement associated with slope failures induces lateral load distributions along stabilizing piles that vary with soil stiffness and strength, pile stiffness and section capacities, and the spacing of piles over the slope.