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Geosynthetics and Geoenvironmental Laboratory
Large-scale Pullout Device
- Pneumatically powered pullout box
- Instrumented with load cell, normal pressure gauge, displacement LVDTs and pore pressure transducers
- Used for simulating the soil-reinforcement interactions in a reinforced slope or MSE wall
- Suitable for testing of saturated or unsaturated soils
- Instrumented to measure geogrid displacements and pore pressures generated during pullout
Large-scale triaxal testing equipment for fiber reinforced soil
- Triaxial device capable of applying extension, compression and tension to a soil sample
- Large-scale specimen size with diameter of 6 inches and a height of 12 inches.
- Capable of applying up to 150 psi of cell pressure and 10000 lbs of axial load
- Currently used for evaluation of the contribution to the soil shear strength of fiber reinforcements
Wide-width geosynthetic tensile testing device with creep and stress relaxation capabilities
- Load frame capable of geosynthetic creep and stress relaxation testing
- Roller grips used to eliminate stress concentrations experienced with clamp-type grips. Wide grips allow for testing of 8-inch wide samples
- A temperature-controlled, insulated environmental chamber allows for temperature-accelerated testing
- Fully instrumented with a load cell, LVDT for specimen displacement measurement, and thermocouples
- Time-temperature superposition techniques are used to characterize long-term creep and stress-relaxation behavior
True-triaxial test device
- Cubical cell capable of testing a tire shred-soil or fiber reinforcement-soil mixture as an elemental cube
- Fully instrumented with LVDTs and pressure transducers
- Automatic backpressure and normal forces may be applied
Centrifuge-based lysimeter for evapotranspirative cover evaluation
- Plexiglass cylinder with water reservoir between two ceramic porous stones
- Suction and soil moisture measured throughout vertical profile while water level is kept constant at near the bottom of the sample
- Weighing lysimeter used to measure variation in water storage, evapotranspiration and basal percolation
- Instrumented for evaluation of the soil-moisture characteristic curve during centrifuge testing and for evaluation of suction gradients associated with surface evaporation
Large-scale, direct shear device with large-displacement capabilities
- Direct shear device assembled within a pullout box, with the top box attached to a pullout tongue
- Top box with dimensions of 450 by 450 mm, and bottom box has dimensions of 450 by 1067 mm
- Instrumented with LVDTs, a 25000 lb load cell for normal loads, a 10000 lb load cell for shear loads and pore pressure transducers
- Low-friction bearings used to minimize friction between top and bottom boxes, with additional bearings so that normal load moves with the top box
- Capable of reaching a shear displacement of up to 600 mm, which is suitable for residual shear strength measurements
- Used to evaluate residual shear strength of claystone and shear strength of tire-shred soil mixtures
Centrifuge-based digital image system for evaluation of strain distribution within geosynthetic reinforced slopes
- Centrifuge has a wireless data acquisition system, which allows improved data transfer, less data storage requirements within the centrifuge and greater monitoring capabilities
- The reinforced slope is outfitted with colored markers along each of the reinforcement strips
- The reinforced slope is spun in the centrifuge until failure occurs at a certain g-level
- During failure, multiple digital photographs are obtained
- Analog camera with remote capabilities for in-flight control
- Digital imaging software used to analyze the succession of pictures and determine the strain distribution within reinforcement layers
Field instrumentation of a tire shred-soil embankment
- Environmental and stability monitoring of a three-section embankment. The first section has a mixture of soil and tire shreds, the second has layers of soil and tire shreds and the third is a soil only control
- Construction took place with careful control of material mixtures, moisture conditions, and density. Construction specifications were implemented for guiding future construction projects
- Settlements are monitored using surveying equipments, and further settlements will be measured using bearing plate equipment
- The three sections of the embankment are subject to the same weather and traffic conditions, making this structure particularly suitable for future long-term monitoring projects
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