Items required
1. Shear box consist of
a) Shear box 60 mm gauge and 50 mm deep.
b) Container for shear box.
c) Grid blades two pairs, one pair plane and other pair percolated.
d) Porous stone one pair.
e) Base plate with cross grooves of top surface.
f) Loading pod with a steel ball on this chalk.
g) Set of weights or normal loads.
2. Loading frame
3. Providing bearing with dial gauge accurate to 0.002 min. to measure shear force.
4. Micrometer dial gauge accurate to 0.001 mm to measure horizontal and vertical displacement during shear (two nos.)
5. Bearing plate strength edge sample trimmer.
Procedure
A) Preparation of test specimen from gradient test
It order to obtain remoulded specimen of concessive specimen the soil may be compacted to the required density and water content in the separate bigger mould. The sample is then extracted and to require size. Non-cohesive soil may be tamp in the shear box itself with the base plate and grid plate of course roll as required in the place at the bottom of the box.
- The shear box is specimen perforated grid plate over the base plate at the bottom of the specimen and one perforated grid plate over the top of specimen should be separated in the position. The separation of grid plates should be placed right angle to the direction of shear plate. The loading pad on the top of grid plate. Both the parts of the box should be tighten together by fixing the screws.
- Put water inside the water jacket so that the sample does not get dried during the paste.
- Mould the shear box assembly on a load frame set lower part of shear box to bear against the load jack and the upper part of shear box to shear against the forming ring set the dial of proving ring to zero.
- Put the loading yocko on the top of loading pad and adjust the dial edge to zero to measure the vertical displacement in soil sample.
- Remove the jacking screw so that both parts are free to move against each other.
- Conduct the test by applying horizontal shear to failure.
Theory
The object of this test is to determine the shear parameter of soil with the help of shear box. The properties with enable soil to maintain equilibrium on a sloping surface is known as shear strength of soil. The shear strength of soil is the resistance to determine the deformation by continuous shear displacement of soil particle on an masses upon the action of the shear stress the shear strength is most difficult to compare and one of the most important if the soil characteristic.
Precautions
1. Soil should be tamped carefully.
2. Dial of proving ring should be adjusted correctly.
3. Soil should be kept wet throughout the complete experiment.
Diagram
Observation
SR.NO. | Normal stress in KN/mm2 | Providing Ring dial gauge (d1) | Shear force in KN | Shear stress in KN/mm2 |
01 | 50 | 7 | 9.2715 X 10-3 | 2.375 |
02 | 55 | 10 | 38.33 X 10-3 | 3.7027 |
03 | 60 | 9 | 11.92 X 10-3 | 3.311 |
04 | 70 | 12 | 15.89 X 10-3 | 4.415 |
B) Water contain of spacimen
1) Weight of container = 15.07 cm
2) Weight of container + wt. of soil = 47 gm
3) Weight of container + dry soil = 40.65 gm
Therefore water content (w) = [(47 – 15.67) – (40.65 – 15.67) / 40.65 – 15.67] X 100
= 25.47 %
Size of the specimen is equal to 60 mm X 16 mm
Graph
Plot the graph shear stress against normal stress which gives a straight line from graph. The value of cohesive of soil and angle of internal friction can be found out.
Result
From graph the parameter of soil with respect to shear strength i.e. cohesion and angle of internal friction are formed out and they are
C = 2.2 KN/m2
Ø = 21.440
