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During each test a sequence of eight 
photographs was taken, the first prior to 
pushing, the remainder at approximately 
1.0 mm upward displacement interval. A 
typical load versus displacement curve is 
given in figure 3. It shows a smooth peak 
followed by a softening stage, the numbers 
on the curve are the serial numbers of the 
photographs. The stereocomparator used 
in . this study was a Zeiss Jena Stecometer 
type C. 
8-DISCUSSION & CONCLUSION 
In this study, the sand used was a uniform 
subrounded sand from Leighton  Buzzard. 
Tests were performed at a relative density 
(I/D) of 75% anda depth/diameter  (D/B) 
ratio of 4. When the anchor is subjected 
to loading the load is transmitted to the 
sand surrounding it. The  deformations 
occuring in the sand were observed and 
recorded. Figures 4 to 7? show the 
displacements and strains for one 
increment of the applied load. Thev show 
the zones of the bed that responded to the 
applied load. It should be noted that 
displacement contours are given in mms and 
maximum strain contours in percentages. 
  
  
  
  
100 120 140 160 
mm 
FIG. 4 : CONTOURS OF VERTICAL DISPLACEMENTS IN 
LEIGHTON BUZZARD SAND, 
D/B=4. ID = 75%, 9 = 27 mm. 
  
  
  
  
  
T I [ 
100 120 140 160 
mm 
FIG.5: CONTOURS OF HORIZONTAL DISPLACEMENTS IN 
LEIGHTON BUZZARD SAND, 
BiB=4, 10=75%, 
  
5 = 2.7 mm. 
For a vertical displacement of 2.7 mm, it 
can be seen that the zone of sand 
responding to this increment of load 
extends approximately from 0.125 B to 2.0 
B to the side of the plate anchor and a 
clear discontinuity of displacements can 
be seen in figure 6. The vertical 
displacement diminishes as the distance 
above the plate increases. The horizontal 
displacements are insignificant and occur 
mainly above the side of the plate. It 
was observed that it this stage the sand 
has begun to fall into the cavity left 
below the plate anchor as it rises. The 
shear has developed and is extending in a 
generally vertical direction upward from 
the edge of the plate anchor. The 
immedi ate effect of this propagation is 
depicted in figure 7. In this case, the 
shape of the failure surface is defined by 
the shape of the boundary of the disturbed 
zone of sand (i.e. a frustrum of cone). 
The salient observation drawn from this 
study is that the pseudo stereo- 
photogrammetry technique can yield 
accurate measurements and it is possible 
by measuring both the vertical and 
horizontal displacements within the sand 
bed to establish the relative displacement 
occuring throughout the bed for any 
increment of displacement of the anchor. 
It is therefore possible to build up 
information on displacements in the sand 
bed increment by increment throughout the 
loading and displacement of the anchor.