ASCE has honored Patrick J. Fox, Ph.D., P.E., D.GE, F.ASCE, with the 2024 Thomas A. Middlebrooks Award for the paper “Analytical Solutions for Internal Stability of a Geosynthetic-Reinforced Soil Retaining Wall at the Limit State,” Journal of Geotechnical and Geoenvironmental Engineering, October 2022.
The author’s paper has made a seminal and transformative contribution to our profession regarding analysis of internal stability of geosynthetic-reinforced soil (GRS) retaining walls. It presents closed-form analytical solutions for the critical failure plane angle and the sum of maximum reinforcement loads for a GRS retaining wall at limit equilibrium. Numerous parameters are considered, including wedge geometry, soil shear strength (cohesion and friction), porewater pressure, reinforcement inclination, surcharge stress, constant applied loads, pseudo-static seismic loads, and toe resistance forces.
Fox takes an approach different from that of others, treating the soil wedge and facing column as a combined block with a vertical load factor to account for soil down drag on the back of the column. This prevents the longstanding problem of characterizing internal forces between the facing column and reinforced soil mass. The author also specifies toe reaction forces as input for the method. He provides a detailed analysis of the literature to support this approach and employs a novel way to estimate these forces based on classical Coulomb theory.
The new solutions represent a next advancement of classical earth pressure theory, following Coulomb (1776), Rankine (1857), and Mononobe-Okabe (1929). Similar to these theories, the solutions directly provide critical conditions at failure without having to perform an iterative search of the problem domain. In addition, the solutions go well beyond the classical theories and account for other important factors.
The Thomas A. Middlebrooks Award is made to the author or authors of a paper published by the Society judged worthy of special commendation for its merit as a contribution to geotechnical engineering. Papers written by young engineers are given preference.
