Determination of Shear Strength of Soil Samples: Consolidated-Undrained Test

Описание: Introduction:


Shear strength in reference to the soil is a term used to describe the maximum strength of soil at which point significant plastic deformation or yielding occurs due to applied shear stress. The shear strength of soil with a maximum particle size of 4.75 mm is determined in unconsolidated undrained, consolidated undrained, and consolidated drained conditions.

Methods for determination of unconsolidated undrained and consolidated undrained tests are described below.


EQUIPMENT


Soil shear apparatus and accessories consisting of
1. Shear box, divided into two halves by a horizontal plane, and fitted with locking and spacing screws
2. Box container to hold the shear box
3. Baseplate having cross grooves on its top surface
4. Grid plates, perforated, 2 Nos.
5. Porous stones, 6mm thick, 2 Nos.
6. Loading pad
7. Loading frame: It shall satisfy the following requirements:
a) The vertical stress on the sample shall remain vertical and constant during the test and there shall be an arrangement to measure compression.
b) The shear stress or strain can be applied in the dividing plane of the two parts of the shear box.
c) It shall be possible to maintain a constant rate of increase in stress during the test (irrespective of the strain rate) with an arrangement to get different rates of stress increase.
d) In the case of a strain-controlled apparatus, the strain rate should remain constant irrespective of the stress. A suitable arrangement shall be provided to obtain different strain rates.
e) No vibrations should be transmitted to the sample during the test and there should not be any loss of shear force due to friction between the loading frame and the shear box-container assembly.
8. Loading yoke
9. Weights - for providing the required normal loads
10. Proving ring-force measuring device fitted with a dial-gauge accurate to 0.002 mm to measure the shear force. Capacity: 100 to 250 kg capacity, depending on the type of soil.
11. Dial gauges, accuracy 0.01mm, 2 Nos. one suitably mounted to measure horizontal movement and the other suitably mounted to measure the vertical compression of the specimen.
12. Sample Trimmer or Core Cutter.
13. Balance - of 1 kg capacity, sensitive to 0.1 g.
14. Spatula and a Straight Edge
15. Stop Clock




Instructor: Dr. Radhakanta Koner, Department of Mining Engineering, IIT(ISM) Dhanbad

Students: MTech students of Mining Engineering, IIT(ISM) Dhanbad

Course Name: Geomechanics Practical (MNC505)

Session: 2020-21, Monsoon

Acknowledgment
Prabhat Kumar Mandal
Krishna Murari
Birju Gope
Vijay Karanga