• 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 TRIAXIAL 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

Triaxial compression of fiber reinforced sand

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

A geotextile specimen confined in the roller grips

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

View of the true-triaxial device

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  

Saturated seepage test using a sand column 

• 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 

Assembly of the normal load application device

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

Camera setup of centrifuge arm

Reinforced soil slope model

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

Monitoring tubes for temperature, relative humidity and gas content equipment

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