Simplified Trial Wedge Method for Soil Nailed Wall Analysis

Abstract

This paper presents a new approach that allows soil nailed walls to be analyzed using a trial wedge method. Most soil nailed wall analysis methods are rooted in traditional slope stability solutions with curvilinear or bilinear slip surfaces. This has led to limited access to these methods due to the cost of commercial software. In addition, there are at least two well-documented test walls brought to failure that indicated evidence of relatively steep, approximately linear slip surfaces instead of the more complex surfaces assumed by most software packages. The simplified trial wedge method is intended as a relatively simple and inexpensive method for preliminary or supplemental design calculations for soil nailed walls. The method stems from the existing Federal Highway Administration analysis guidelines. Procedures are outlined for implementing the trial wedge method using a spreadsheet-based approach. The method is applied to two test walls that were intentionally brought to failure, the Amherst Test Wall in clay, and the Clouterre Test Wall No. 1 in sand. In each case, the trial wedge analysis produces results consistent with the failure mode of the wall.