WATER JET CONFERENCE - Waterjet Technology Association

Materials Tested
Four different soils with a substantial variation in engineering properties and
behavior were subjected to the jet cutting experiments. The grain size distributions of
these soils are shown in Figure 1.
Soil 1 is a readily available clean sand (Ottawa sand); soil 2 is a mixture by weight
of 85% locally available sand (torpedo sand) and 15% natural silty soil (Vicksburg loess);
soil 3 is a naturally occurring silty soil (Vicksburg loess); and soil 4 is a mixture by weight
of 50% naturaliv occurring clayey soil (Chicaqo area clay) and 50% commercially
available kaolinite. According to the Unified Soil Classification System these materials
are classified as SP, SW, ML, and CL, respectively.
Sample Preparation and Testing Procedures
The following factors were taken into consideration for the selection of an
adequate sample container:
(a) the container should be impervious as soil samples in a saturated and partially
saturated state would be tested;
(a) the container should be large enough to avoid any adverse interference from the
container walls while the sample was being exposed to the jet;
(a) the total weight of container and sample should be small enough to allow its
convenient handlinq and transportation from an area of preparation to the location of
the water jet system; and
(a) the container should be able to be placed upon the lathe which was utilized to traverse
the samples.
Therefore, various lengths of six inch inside diameter PVC (plastic) pipe were chosen as
appropriate sample containers This sample container also lended itself very nicely to the
compaction of samples with a manually operated drop hammer.
To prepare a sample, dry pulverized soil was weighed and mixed with a
predetermined amount of water to attain the desired degree of saturation. Frequent checks
of moisture content were made to insure adequate control. Then a specific weight of the
moist soil was placed in the container and was compacted (by vibration or using a drop
hammer) to a predetermined layer thickness in order to attain the desired dry density.
Enough layers were thus compacted to obtain the desired length of sample. Deviations
from this procedure were necessary onlv when preparing samples of Soil 1. In this case, a
sample of the desired length and dry density was first formed and was then saturated by
allowing water to flow up through the sample by means of a valve at the base of the
container; to obtain a partially saturated sample, some of the water was allowed to drain
through the bottom of the container.
Soils 1 and 2 were placed in the containers in two inch lifts and between each lift
was placed a four inch square paper marker which was numbered. The thickness of each
layer was checked in order to insure adequate density control. The paper markers were
used with these cohesionless soils since the holes or slots excavated by the water jet had a
tendency to collapse. At the end of each test the depth of jet penetration could be
established to within one inch by gradually emptying the container and inspecting the
markers for signs of penetration by the jet. The diameter of the hole excavated was
estimated as the average of the diameter of the holes present on the markers penetrated by
123