There are mainly four reasons for this test:
(i) To check and verify the bond strength between soil and grout adopted during the design of soil nails. This is the main objective of conducting soil nail pull-out test.
(ii) To determine the bond strength between soil and grout for future design purpose. However, if this target is to be achieved, the test nails should be loaded to determine the ultimate soil/grout bond with a upper limit of 80% of ultimate tensile strength of steel bars.
(iii) To check if there is any slippage or creep occurrence.
(iv) To check the elastic and plastic deformations of test nails. This is observed during the repeated loading and unloading cycles of soil nails.
Note: Pull-out tests are carried out by applying specified forces in an attempt to pull out the constructed soil nails.
This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.