Pullout Resistance of MSE Reinforcements in Backfills Typically Used in Texas: Volume 3, Test Reports for MSE Reinforcements in Type A (Gravelly) Backfill.

摘要

This report documents findings from a three-year research study that examined the pullout resistance of inextensible MSE reinforcements in backfills typically used in Texas. The study involved an extensive laboratory test program in which a total of 687 pullout tests were completed. These tests were conducted using a large scale pullout test system that consisted of a test box with dimensions of 12ft x 12ft x 4ft and capability to simulate overburden pressures equivalent to 40 feet of fill. Tests were conducted on ribbed strip reinforcements, welded steel grid reinforcements, and a limited number of smooth bars embedded in two types of backfill, designated as Type A (gravelly) and Type B (sandy) select backfill as per TxDOT specifications. A subset of strip and grid reinforcements in each backfill type was instrumented with strain gages to provide further insight into mechanisms that control pullout resistance. The research design evaluated pullout resistance factors for both strip and grid reinforcements for a variety of independent variables including overburden pressure, reinforcement length, skew or splay angle, grid wire size, and grid geometry including both transverse and longitudinal wire spacing. Appropriate statistical analyses were used to interpret the data within the context of published AASHTO design guidance for inextensible MSE reinforcements. This volume, Volume 3, presents pullout test reports from a total of 320 pullout tests completed on MSE reinforcements embedded in TxDOT Type A backfill, and accompanying strain gage test reports. Volume 1 summarizes the research findings, and Volume 2 presents test reports for reinforcements in Type B backfill.