Effect of low plastic fines content in the backfill of mechanically stabilized earth wall on wall performance
摘要
Mechanically stabilized earth (MSE) walls are considered an attractive alternative to conventional cast-in-place concrete walls due to their cost efficiency and feasibility. Conventionally, marginal soil is desirable as a backfill for MSE walls due to the high cost of replacement with clean sand and potential environmental effects. The primary objective of this study is to investigate the effect of fines content in the backfill of MSE walls on wall performance.
The effect of fines content on clean sand properties was determined to investigate the potential of using sand with fines as a backfill. A series of laboratory tests were performed to investigate the impact of low-plastic silty/clayey fines on the properties of clean sand. Poorly graded sand was mixed with fines content varying from 0 to 40%.
The effect of fines content on the sandy soil-geogrid interface properties was evaluated by collecting data from the geotechnical literature, and regression analyses were conducted to determine the interface strength reduction factor (Rinter) used in the numerical modeling of the wall under study. Rinter values obtained from regression analysis were observed to range from 0.95 in the case of clean sand to 0.53 in the case of sand with 40% fines. Finally, finite element models, developed using Plaxis 2D, were created for a 4.4 m high MSE wall with different backfill mixtures, utilizing estimated soil and interface properties. The maximum horizontal wall movement increased as the fines content increased. The horizontal wall strain increased from 0.66% in the case of clean sand backfill to 1.52% in the case of 40% fines content. However, by increasing the fines content to 40%, a 63% decrease in the pull-out safety factor for internal stability and a 51% decrease in the sliding safety factor for external stability were encountered.