Germany wille The automated large direct shear apparatus has been designed and manufactured according to version of current testing standards (ASTM,ISO, EN and DIN) and manufactured by high quality of mechanical and electronic parts. This quality makes it unique to produce repeatable test results.
The device determines the internal friction of construction materials e.g. soils, aggregates, gravels, geomembranes, geotextiles, GCL(Geosynthetic clay liner), recycling rubble Brick rubble, Colliery spoils, and industrial slag. The interface friction parameters between different construction material could be also determined by the device e.g. geotextile /soil, geotextile /concrete, asphalt/concrete, geogrid/soil and etc.
This floor mounted direct shear device is an automated apparatus to test large samples of300x300mm or 500x500mm and 1000x1000mmsizes. It has variety range of axial and shear loaded up to 250kN and even larger loads for1000x1000mm sample size. The set-up of the test parameters can be done either via the front operational panel which includes of control buttons and function keys with LCD display or directly by software. GEOsys software in combination with this unit performs all your tests automatically and without operator assistance during the test period.
This large direct shear apparatus measures the force developed during the relative displacement of two surfaces subject to normal stress or internal shearing of soil in accordance with international standards. In the Direct shear test a cuboid or circular specimen is installed in a shear box which consist of two parts and subjected to vertical and horizontal stresses. The lower shear box is moving against the upper one therefore a shear surface would be generated, in which a shear stress builds up. The shear box prevents the sample to have lateral expansion.
System Geography
① Axial force Electromechanical actuator
② Shear force Electromechanical actuator (Inside - Invisible)
③ Electronic and Control Unit (Inside - Invisible)
④ Main Switch and front operating panel
⑤ Moveable Gantry
⑥ Stiff framework
⑦ Upper Shear Frame
⑧ Lower Shear frame
⑨ Water container
⑩ 4 off axial displacement transducers
⑪ Shear force load cell (Invisible)
⑫ Axial Force load cell
⑬ compression Spring for compensating of the weight of upper shear box (2 off)
⑭ Locking brake
Large Direct Shear Test Device
The device has two electromechanical for ceactuators includes of stepper motor and gearbox which applies normal stress and shear stress on sample with closed loop control function means each axis would be controlled in displacement(strain or velocity) mode as well as load control mode. The apparatus with reversible electromechanical motor gives the possibility to run residual strength test.
The device has rigid construction which the unwanted deformation of any parts during the tests. The device has a special floating frame construction to compensate wall friction influences and compensation of tilting. The Lower part of shear box is locating on a frictionless preloaded bearing and moves with the friction just in horizontal direction in dependent from axial load.
This device eliminated the manual loading for dead weights or pneumatic version which needs air pressure for operation.
The main advantage of device is an accurate testing of specimen without tilting and friction between shear box components (e. g. load piston, upper shear box, lower shear box). The normal stress and the shear stress are closed loop controlled by an electromechanical drive system. It has a Closed-loop control of normal stress by comparing the effective stress in the shear gap with the rated value.
The apparatus has a movable gantry which slides the axial force actuator to right side of device to provide convenient and free space for operator to handle the shear box/es and set up it for testing from above. The easy handling of this mechanism is guaranteed. The locking brake fix this mechanism at the desired place either at test point or at sample set up point and prevent any horizontal movement.
Shear Box
The complete shear box system is made of stainless steel and is designed to contain water that surrounds the specimen and allows the specimen to be submerged for saturate conditions. The shear box consists of lower and upper shear boxes with rigid wall either in round or square shape, adaptor loading pad, two porous plates, load piston and water container for saturated conditions.
The stainless-steel shear box system is prevented completely against tilting, consists of a moving lower shear box comes with friction free linear guides and moves with the small friction just in horizontal direction. The upper shear box is vertically floated, and weight compensated and fitted to parallel linear bearings. It can be also fixed at its place as well.
The spacing between the upper and lower shear boxes (shear gap) is adjustable and can be adjusted continuously up to 35 mm. The weight of the floating upper shear frame and the upper shear box can lead to measuring errors during test cycles. Therefore, their mass is transferred directly into the machine’s framework by using two compression springs located at two sides.
The design of the equipment allows the sample to be compacted without damaging the measuring devices. The shear boxes are removeable from testing position and after compaction and preparation of sample would be moved back to testing place at frame again. The shear boxes have adapters which enables to reduce the sample size or even the shape of sample into circular one which showed in below pictures.
SIEMENS Industrial Controller
The operation of the device requires the direct input of numerical values besides the use of the function keys. The control element made by Siemens Company is an advanced control panel which allows the user to enter the numerical values and control the system by other function keys easily. You need just to enter the values and press the run Key to start the operation.
The operator panel gives the user access to all functions in the operation and service menu. This enables the user to start and run the pump as well as conduct calibration if needed. These controls are instinctive and simple to use. All functions, such as actual status, flow rate and information on the pressure pumping ramp can be seen on the LCD display on the front of the device.
Main Features
• Graphic display including 10 input membrane keys
• Setting force or position manually
• CE mark
• Ethernet interface
• 22 available different languages
• Multi language menu navigation
• Calibration function
• 4 free analogue Ports with A/D converter (interface+ /- 10 VDC)