Refinement of K-stiffness Method for geosynthetic-reinforced soil walls

Abstract

The K-stiffness Method is an empirically-developed working stress method used to compute reinforcement loads for the internal stability design of geosynthetic-reinforced soil walls under serviceability conditions. In this paper, additional data from Japanese case studies for five full-scale field and three full-scale laboratory geosynthetic-reinforced soil walls are added to the database that was used to calibrate the original K-stiffness Method. One more case study from an instrumented wall in the USA is also introduced. Measured loads are compared with predicted loads using the current AASHTO Simplified Method and a modified version of the K-stiffness Method that has been adjusted by back-fitting model parameters to the extended database. The AASHTO Simplified Method is shown to be excessively conservative (on average) with respect to accurate prediction of reinforcement loads and to correlate poorly with measured values. The modified K-stiffness Method is demonstrated by statistical analysis to give ratios (bias) of average measured to predicted reinforcement load values close to 1 and coefficient of variation (COV) values for the maximum reinforcement load in a wall that are less than 25%.

Modelling deformation during the construction of wrapped geogrid-reinforced structures

“…These have been briefly summarised in Table 1. The most prominent of these is the 'K-stiffness method', first presented by Allen et al (2003) and later updated by Bathurst et al (2008) and more recently by Allen and Bathurst (2015). It incorporates a number of empirically calibrated parameters that enable the calculation of maximum tension and strain deformation in each layer.…”

“…This guidance has been developed for vertical GRS, the most sensitive condition, and does not account for facing batter in sloping structures. Work by Bathurst et al (2008), suggests a non-linear reduction factor between facing batter and stress in the structure, but it is unclear how this translates to construction method deformation, without further detailed analysis.…”

Measured and Predicted Loads in Multi-Anchor Reinforced Soil Walls in Japan

“…These walls were constructed to examine the eŠect of foundation support on wall performance. Other walls in this series were constructed with geosynthetic reinforcement layers and have been described by Bathurst et al (2008a). The soil type and compaction were the same in both structures.…”

Evaluation of Geosynthetic Reinforced Soil Wall Using Limit Equilibrium Analyses

“…Compared to the LE analysis, the lateral earth pressure method also cannot evaluate global stability directly. Allen et al (2003) and Bathurst et al (2008Bathurst et al ( , 2005 investigated quantitatively the accuracy of reinforcement loads predicted by the earth pressure theory using careful interpretation of a database of 30 well-monitored full-scale walls on firm foundations and reinforced fills with no positive pore water pressures. By the comparison between the reinforcement loads (estimated from measured strains) in various instrumented GRS walls and the reinforcement loads predicted using the earth pressure theory, they concluded that loads predicted using earth pressure theory were excessively conservative.…”