Author: James J. WaltersPublisher:
ISBN:
Category : Retaining walls
Languages : en
Pages : 245
Book Description
In many geotechnical design situations involving tight right-of-way constraints, Mechanically Stabilized Earth (MSE) walls are often the most cost-effective and reliable earth retention technology among available alternatives. However, few well-documented case histories with detailed material testing, instrumentation programs and construction observation of performance are available in the literature. Despite the small number of case histories, empirical design methods are used in place of more theoretically-based methods. As a result, current design methods for MSE walls result in a large amount of inaccuracy, especially when their empirical calibration limits are exceeded. This study characterizes the constitutive behavior of a sandy gravel backfill soil and ribbed steel strip reinforcement material used in the construction of two very tall MSE walls constructed during the 3rd Runway Expansion Project at the Seattle-Tacoma International Airport (SeaTac). Tension testing was performed on coupons cut from the reinforcement material in order to measure its Young's modulus and yield strength. Consolidated drained triaxial strength testing was performed to measure the stress-strain behavior of the loose, medium dense, and densely-compacted backfill materials. Then the frictional interaction between the reinforcement and densely-compacted backfill soil was evaluated by performing twenty full-scale single-strip laboratory pullout tests. Using the results from the material testing and in-situ reinforcement strain measurements taken at the SeaTac MSE walls, the accuracy of four reinforcement load prediction methods was evaluated. The pullout test results were used to develop a backfill-specific design model, as well as being combined with other pullout test results for gravels reported in the literature to develop a global gravel design model for predicting peak reinforcement pullout resistances. These newly developed pullout design models were compared to the current AASHTO design model and found to produce much more accurate predictions of peak reinforcement pullout resistance. Walls designed and constructed with the kinds of backfill evaluated herein and with the new models generated will be more cost-effective than typically accepted design models.