Standards:BS 1377-7; ASTM D 6243; EN ISO 12957
The test covers the determination of consolidated drained shear strength of a soil material in direct shear. The machines are ideal for determining shear resistance of soil-geosynthetic / geomembrans by direct shear.
Automatic Direct / Residual Shear Test Machines are motorized and floor mounted. The total vertical load on the specimen can reach up to 100 kN.
ZI 3088 accepts up to 300 mm square shear box assembly. ZI 3088A accepts from 450 mm to 650 mm square shear box assemblies. All shear box assemblies are designed to contain water that surrounds the specimen. The Assemblies consist of a shear box with a rigid wall square or round hole complete with a vertical loading pad two retaining plates (one is smooth, the other is peforated) The shear machines are driven by high resolution servomotor and gear box assembly. Speed range is fully stepless variable over the range 0.00001 to 9.99999 mm/min for both direction (forward and reverse). After test the reverse speed is 10 mm/min.). 100 kN load cell is used for load measurement. 200 x 0.01 mm sensitivity linear potentiometric transducers are used for vertical and horizontal displacement measurements. Horizontal Displacement limits are controlled by limit switches.
Display Unit and Controller
The 240x320 TFT Graphic Display is used for monitoring horizontal and vertical load and displacement values. All test parameters such as speed, failure condition etc. Can be defined through this interface. The test can be started up and stopped by touch buttons.
The controller has two indepent control axes, on efor horizontal motion on efor vertical motion. The displacement on horizontal motion is measured through external displacement sensor fitted to frame and also through the encoder behind the servo motor. All calibration of sensors can be done easily by entering new points respect to the error.
The software is capable of monitoring all measured values and drawing Shear stress vs Horizontal displacement. After three runs with different normal loads, the software calculates the cohesion value “c” and shear resistance angle”f” by using the best straight line fit.
User can select 3 different test types:
Direct residual and shear software consist of two sections. First section is used for the consolidation of the sample prior to shear.
The software is capable of making three different types of test. The first type of the tests is to move the machine till a load failure happens. On the second type of test the user can set a horizontal displacement and the test will continue till the machine reaches set value. On the last type of test, the machine can be configured as going to a set horizontal displacement value and return to home position. The software supports 5 different normal load values in order to calculate cohesion values. Prior to the test normal load value must be entered to the software. The normal stress value would be calculated respect to normal load and sample size automatically. The software supports both square type and round type samples. For both samples the area might be calculated by directly or by using the net area caused by horizontal displacement. The net area method is especially important for critical samples on academic literature. When the test is completed max and resilient stress values are recorded. The normal load versus max stress pair is used for calculating the cohesion value and angle. At least 3 loading with different normal loads are required for this property. One can set test speed, axis values etc through the setup of the software. The results can be submitted as a report or can be exported to Microsoft Excel for advanced reanalyze procedures.
The Automatic Direct Residual Shear Test Machine is supplied complete with