30 June 2001
(a) It is not necessary to reference deformations to the equipment, which deforms
(b) The effect of end-cap restrain on soil response is virtually eliminated.
(c) Any effects of piston friction are eliminated by measuring loads inside the triaxial
(3) In addition to the measuring devices it is also necessary to maintain suitable recording
equipment. Simultaneous recording of load and deformation is desirable. The number of recording
channels can be reduced by wiring the leads from the LVDTs so that only the average signal from
each pair is recorded. The introduction of switching and balancing units permits use of a single-
c. Additional Equipment. In addition to the equipment described above, the following items
are also used:
(1) A 9- to 27-metric ton- (10- to 30-short ton-) capacity loading machine.
(3) Rubber membranes, 0.25 to 0.635 millimeter (0.01 to 0.025 inch) thick.
(4) Rubber O-rings.
(5) A vacuum source with a bubble chamber and regulator.
(6) A back-pressure chamber with pressure transducers.
(7) A membrane stretcher.
(8) Porous stones.
L-7. PREPARATION OF SPECIMENS AND PLACEMENT IN TRIAXIAL CELL. The following steps
should be followed in preparing and placing specimens:
a. In accordance with procedures specified in paragraph L-5, prepare the specimen and place
it on the baseplate complete with porous stones, cap, and base and equipped with a rubber
membrane secured with o-rings. Check for leakage. If back-pressure saturation is anticipated for
cohesive soils, procedures indicated in paragraph L-5a should be followed. For purely noncohesive
soils, it will be necessary to maintain the vacuum during placement of the LVDTs. The specimen is
now ready to receive the LVDTs.
b. Extend the lower LVDT clamp and slide it carefully down over the specimen to
approximately the lower third point of the specimen.
c. Repeat this step for the upper clamp, placing it at the upper third point. Ensure that both
clamps lie in horizontal planes.