Centrifuge permeameter for unsaturated soils system

The present invention includes an apparatus, method and centrifuge permeameter system that includes a hydraulic permeameter adapted for use in a centrifuge; and an automated data acquisition system, wherein the centrifuge permeameter non-destructively determines one or more soil characteristics from a sample of granular material such as soil, rock, and concrete when centrifuged.Board of Regents, University of Texas Syste

Evaluation of Seamless Bridges

0-7011The research study included experimental testing and numerical modeling to obtain and develop much needed experimental data and analytical tools to study the performance of seamless systems, identify design issues, and propose design guidelines for the U.S. practice

Research report (University of Texas at Austin. Center for Transportation Research)

Abstract: "Geotextiles, one among the different geosynthetic products, can be used for a number of functions or applications in pavement design. The benefits of using geotextiles in pavements and other transportation applications have triggered a proliferation of products. While this abundance of new products has led to reduction in costs, it has also made it difficult for TxDOT personnel to choose appropriate products based on their engineering properties. Consequently, this report provides the basis for (i) guidelines for proper use and selection of geotextiles in pavements, (ii) material specifications for geotextiles in pavement applications, and (iii) draft construction specifications.

Advances in the Use of Geosynthetics for Stabilization of Unbound Aggregate Layers

The governing mechanism associated with the stabilization of unbound aggregate layers in pavements is lateral restraint. Reproducing this mechanism in the laboratory maybe challenging because, while the original loading source is cyclic (traffic), lateral restraint develops through interlocking and interfacial friction between the geosynthetic and the aggregate to restrain the development of permanent lateral strains. Considering the relevance of lateral restraint in the quantification of the benefits of geosynthetics embedded within (or adjacent to) unbound aggregate layers, this study focuses on two experimental approaches to quantify this mechanism. The first experimental approach aims at defining a design parameter, identified as the Stiffness of the Soil-geosynthetic Composite (KSGC), which is obtained from Soil-Geosynthetic interaction (SGI) tests and is practical for use in specifications and design. The second experimental approach that quantifies the lateral restraint mechanism involves one-third scale accelerated pavement tests (APTs), which were performed on pavement test sections stabilized with various geosynthetics, diverse in terms of geometry and materials. The rutting from these sections was compared to that in the non-stabilized (control) section to evaluate the Traffic Benefit Ratio (TBR) at failure rut depth for each geosynthetic. The TBR obtained showed a strong linear correlation to the KSGC of the corresponding geosynthetic determined by SGI tests. Overall, the KSGC parameter was found to represent a suitable indicator of the performance of pavements with unbound aggregate layers stabilized using geosynthetics

Interaction mechanisms in small-scale model MSE walls under the strip footing load

The effect of preloading on mechanically stabilised earth (MSE) has remained an aspect difficult to quantify in design, particularly when considering different reinforcement types, stiffness values, and facing rigidity. This study analyses several scaled model tests on MSE walls under a strip footing load with a single unloading-reloading cycle. Scaled models were constructed as part of this investigation to expand the evaluation of previously constructed full-scale tests. The strip footing load and wall deflections were measured and compared with analytical models. The failure mechanism of the soil, before and after the strip footing load, was included in the study via the particle image velocimetry (PIV) method. The results indicate that the bearing capacity of a strip footing is higher for a rigid facing than for a flexible facing. PIV analysis results for the first and second loading step formed two failure lines with the angle (π/4 + φ/2). The deflection values in the second loading step, however, were smaller than those reached during the first loading in small-scale tests. Good agreement was observed between the proposed analytical method and experimental results for the second loading step, after taking into account the preloading effect