Plate load test
1. SAYAN SARKAR
2. SAYANTAN SINGHA ROY
3. SHOUVIK BANERJEE
4. SHADMAN KHAN
6. SNEHANGSHU SEKHAR
PLATE LOAD TEST AND STANDARD REFERANCE (IS:1888-1982)
i) Plate Load Test is a field test for determining the ultimate bearing
capacity of soil and the likely settlement under a given load.
ii) Circular or square bearing plates of mild steel not less than 25mm in
thickness and varying in size from 300 - 750mm.
iii) The subgrade modulus is defined as the load intensity ‘p’ applied on the
standard plate per unit deflection i.e. k=p/d, value of d=1.25mm. The test
load is gradually increased till the plate starts to sink at a rapid rate.
iv) The ultimate bearing capacity of soil is divided by suitable factor of
safety (which varies from 2 to 3) to arrive at the value of safe bearing
capacity of soil.
(i) Test plate of square size
(ii) Hydraulic jack & pump
(iii) Pressure gauge
(iv) Proving ring or load cell
(v) 4 no of dial gauges & dial gauge stands
(vi) Magnetic bases for dial gauges & supporting channels
(vii) Loading platform equipment or Truss with anchor rods
(viii) Plumb bob
(ix) Sprit level
(xi) Pulley block
(i) To conduct the plate load test a pit of size 5Bp x 5Bp where Bp=width of plate, is
excavated up to a depth of Df where Df=depth of proposed foundation.
(ii) Generally 0.3 m2 plate is used and sometimes 0.6 m2 plate are also used. so Bp=0.3
(iii) A central hole of depth Dp is made at the bottom of the test pit where,
(iv) The plate is placed in the central hole and load is applied on it by a hydraulic jack
(v) A seating load of 7 kn/m2 is first applied and released after some time .After that
load is increased in increment of 20% of rate estimated load or 1/10th of ultimate
i) To find out the ultimate
bearing capacity of the
ii) To determine the
settlement of a footing
under a given load
iii) We can design a
shallow footing for any
(i) The Plate Load Test being of short duration , does not give the
ultimate settlements particularly in case of cohesive soils.
(ii) The width of the plate should not be less than 30cm. It is
experimentally shown that the load settlement behaviour of soil is
qualitatively different for smaller width.
(iii) The foundation settlements is loose sands are usually much
larger than what is predicted by plate load test.
(iv) The settlement influence zone is much larger for the real
foundation sizes than that for the test plate.
i) Time-saving and cost-
ii) No vehicle required
iii) on-site evaluation of test
iv) Easy to handle
v) Reliable and precise