30 June 2001
d. Connect the LVDTs to the recording unit, and balance the recording bridges. This step will
require recorder adjustments and adjustment of the LVDT stems. When a recording bridge balance
has been obtained, determine (to the nearest 0.25 millimeter (0.01 inch)) the vertical spacing
between the LVDT clamps and record this value.
e. Place the triaxial chamber in position. Set the load cell in place on the specimen.
f. Place the cover plate on the chamber. Insert the loading piston and obtain a firm
connection with the load cell.
g. Tighten the tie rods firmly.
h. Slide the assembled apparatus into position under the axial loading device. Bring the
loading device to a position in which it nearly contacts the loading piston.
I. If the specimen is to be back-pressure saturated, proceed in accordance with paragraph L-5.
j. After saturation has been completed, rebalance the recorder bridge to the load cell and
L-8. RESILIENCE TESTING OF COHESIVE SOILS.
a. General. The resilient properties of cohesive soils are only slightly affected by the
magnitude of the confining pressure F3. For most applications, this effect can be disregarded.
When back-pressure saturation is not used, the confining pressure used should approximate the
expected in situ horizontal stresses. These will generally be on the order of 0.0069 to 0.034 MPa
(1 to 5 psi). A chamber pressure of 0.021 MPa (3 psi) is a reasonable value for most testing. If
back-pressure saturation is used, the chamber pressure will depend on the required saturation
b. Resilient Properties. Resilient properties are highly dependent on the magnitude of the
deviator stress Fd. It is therefore necessary to conduct the tests for a range in deviator stress
values. The following procedure should be followed:
(1) If back-pressure saturation is not used, connect the chamber pressure supply line and
apply the confining pressure (equal to the chamber pressure). If back-pressure saturation is used,
the chamber pressure will already have been established.
(2) Rebalance the recording bridges for the LVDTs and balance the load cell recording
(3) Begin the test by applying 500 to 1,000 repetitions of a deviator stress of not more
than one-half the unconfined compressive strength.
(4) Decrease the deviator load to the lowest value to be used. Apply 200 repetitions of
load, recording the recovered vertical deformation at or near the last repetition.
(5) Increase the deviator load, recording deformations as in step 4. Repeat over the range
of deviator stresses to be used.