7
There is a potential for mining the trona seam about
100 ft (30m) below the current mining horizon. This min-
ing would require additional shaft sinking. An alternative
would be ramp access. Safety of the ramp would be of con-
cern, of course. A finite element analysis of stress provides
guidance in the matter of ramp safety. Again, the simple
three step process is used.
Figure 11 shows a finite element mesh in cross-section.
The arched back cross section is 11×11 ft (3.3×3.3 m) and
is continued through a long-section.
Figure 12 shows the finite element mesh in long section
that begins in the top trona seam, dips 15 deg, and ends in
the lower trona seam as seen in the long section figure.The
pre-ramp stress is caused by gravity alone as in the shaft
analyses. There are 657,720 elements and 680,784 nodes
in the mesh that encompasses 145 element cross-sections.
Run time was approximately 2.5 hrs.
Figure 13 shows the distribution of element safety fac-
tors in a cross-section at the top of the ramp. Figure 14
shows element safety factors in long section. The black
color indicates some yielding at the walls of the section.
Some surface support may be required or the section shape
Figure 11. Ramp in cross-section at ramp top. Ramp is
11×11ft (3.3×3.3 m). White is trona orange is shale, and
blue is oil shale
Figure 12. Ramp mesh in long section. Dip is 15 deg. Ramp is 11 ft (3.3 m) high. White is trona. Orange is shale, blue is oil
shale, and yellow is also shale
There is a potential for mining the trona seam about
100 ft (30m) below the current mining horizon. This min-
ing would require additional shaft sinking. An alternative
would be ramp access. Safety of the ramp would be of con-
cern, of course. A finite element analysis of stress provides
guidance in the matter of ramp safety. Again, the simple
three step process is used.
Figure 11 shows a finite element mesh in cross-section.
The arched back cross section is 11×11 ft (3.3×3.3 m) and
is continued through a long-section.
Figure 12 shows the finite element mesh in long section
that begins in the top trona seam, dips 15 deg, and ends in
the lower trona seam as seen in the long section figure.The
pre-ramp stress is caused by gravity alone as in the shaft
analyses. There are 657,720 elements and 680,784 nodes
in the mesh that encompasses 145 element cross-sections.
Run time was approximately 2.5 hrs.
Figure 13 shows the distribution of element safety fac-
tors in a cross-section at the top of the ramp. Figure 14
shows element safety factors in long section. The black
color indicates some yielding at the walls of the section.
Some surface support may be required or the section shape
Figure 11. Ramp in cross-section at ramp top. Ramp is
11×11ft (3.3×3.3 m). White is trona orange is shale, and
blue is oil shale
Figure 12. Ramp mesh in long section. Dip is 15 deg. Ramp is 11 ft (3.3 m) high. White is trona. Orange is shale, blue is oil
shale, and yellow is also shale