Rock Shear Box Apparatus
Field Shear Box
This apparatus, similar to one developed by Rock one developed by Rock Mechanics Centre, Imperial College, London, is used for practical rock testing
either in the field or laboratory.
The apparatus consists of a shear box in two parts which can accept samples of max. size 115 x 125 mm or cores upto 102 mm diameter. The lower half is fitted with two rams for reversible shearing action, and the upper fitted with a ram for normal load application. The normal loading unit is complete with low friction hardened rods to maintain constant normal load throughout the duration of the test.
The equipment comprises :-
- Hydraulic Pumps – 2 Nos.
- Pressure Gauges – 2 Nos.
- Hose Pipes – 2 Nos.
- Dial Gauge 0.01 x 25 mm – 1 No.
- Perspex sided aluminium mould
Field Shear Box for 300 x 300 x 100mm specimen
The instrument is used for finding out the shear strength of rock specimen at predetermined angle.
It consists of two blocks which, with suitable adopters, can accept specimens ranging from ‘EX’ to ‘NX’ size, with diameter to length ratio of 1:1. The shearing angle can be adjusted at 30o, 35o, 40o, 45o and 50o. It can be used in compression testing machine with day light clearance of approximately 400 mm.
Equipment comprises the following:-
- Set of specimen holders.
- Bottom and top plates.
- Rollers 15 Nos
Servo Hydraulic Rock Shear Equipment
The system comprises of two controllers, hydraulic power pack with Tandem Pump to feed two actuators. Since the size of the box is 300 mm x 300 mm x 450 mm, it can take maximum rock specimens of 300 x 300 x 150 mm, naturally or artificially jointed, in any shape and form. All the parameters like normal load and shearing load either on strain basis or stress basis are controlled through the dedicated computer. On line graphical presentation is shown on the monitor. After the completion of the test the following graphs are plotted in window operated software.
- Shear force Vs Horizontal displacement
- Horizontal displacement Vs Vertical displacement.
- Shear Stress Vs normal stress.
The system includes :-
1) Loading Unit
It is a welded structure fitted with two actuators for normal and shear load. Box assembly can be moved out of the loading unit on the railings provided. This facilitates in the easy loading of the sample.
Capacity of the actuators
- Normal Load : 500kN
- Shearing Load : 750kN
- Strain Adjustment : 0.001 mm/min-50 mm/min.
- Shear box assembly: 300 x 300 x 400 mm.
Comprises of :-
- Shear box housing in two halves.
- Spherical seating
- L.V.D.T. ± 20 mm for vertical strain : 2 Nos.
- L.V.D.T. ± 20 mm for horizontal strain : 2 Nos.
- Load Cell for Shear Load, 750kN capacity : 1 No.
- Bottom Plate : 1 No.
- Casting Mould : 1 No.
- Load Cell for normal Load 500kN : 1 No.5)
Capacity of the oil tank : 100 Ltrs.
Pumps tandem type : 30 Ltrs/min.
HP of the motor : 15 HP
Heat Exchanger : 10,000 k cal/hr.
Servo Valves : Moog/Tokyo
Operating Pressure : 20 mPa.
Pressure Line Filters : 3 Microns Absolute
Accumulators : Piston Type, 1 Ltr. Capacity.
6) Computer Pentium IV with Data Acquisition Card (Dedicated)
Note : Higher sizes upto 1000mm x 1000mm x 1000mm on request
Slake Durability Test Apparatus
This apparatus is used to assess the resistance offered by a rock sample to weakening and disintegration when subject to drying and wetting in a slaking
fluid, usually water. The equipment meets the essential requirements of IS:10050-1981 and comprises the following
- A motor drive with reduction gear mounted on a base board and capable of rotating four drum assemblies at a constant speed of 20 rev/min approximately.
The motor drive is totally enclosed in a hinged cover for quick accessibility to the drive for test set up. An operating switch is provided in the cover.
- Two test drums made of brass wire mesh, with one end closed and having a removable cover on the other end. It has suitable couplings for mounting in the perspex water troughs. The drums are 140 mm in diameter and have an unobstructed length of 100 mm.
- Two perspex water troughs, accommodate one test drum each. These drums carry quick couplings on either end which are in turn coupled with
couplings of the motor drive. The troughs allow 40 mm unobstructed clearance below the test drum. A water level mark is provided in each water trough 20 mm below the axis of rotation of the drum.
Suitable for operation on 220 v, 50 hz, single phase supply.
Rock Classification Hammer
This light weight and portable compact hammer is used for rock classification test. Cylindrical cores, usually ‘NX’ size are held in horizontal position and the hammer mechanism impacted against the core to obtain rebound value. A series of rebound values are taken along the length of the core or rock mass to obtain average value.