Engineering Rock Mechanics
382 Design of underground excavations 6~ = (56.20 - 3.304~~ - 0.533~~) x 1 0-3 6c = (56.20 - 0.533~~ - 3.304~~) x 1 0-3 6~ = (56 ...
Question and answers: design of underground excavations 383 To determine the initial strain, we use the general form of Hooke’s ...
384 Design of underground excavations Three-pillar system For the three-pillar layout, we have the following three ground charac ...
Question and answers: design of underground excavations 385 approach is required to solve the system. The iteration follows the ...
386 Ground and pillar characteristics at iterations 11 and 12: 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 O.OE+OO 2.OE-03 4.OE-W 6.OE-03 ...
387 These values can be seen to be identical to those obtained by iteration. Clearly, the second of the two designs is preferabl ...
388 ~~ ~~ Strain proportion Ratio of distance from panel centre to deDth 0.00 0.02 0.11 0.19 0.24 0.29 0.31 0.38 0.42 0.49 0.52 ...
389 c v) 0.0 Notice that the strain profile is drawn using the sign convention given in the SEH, which is tension positive. 50.0 ...
390 With the depth to the panel being 500 m, and the maximal subsidence being 0.72 m, the strain profile is given in the table a ...
391 A20.7 (a) When A is very small, the expression (ac)pILLAR = 10+45e-' tends to a value of 55 MPa - this is the laboratory com ...
392 60.0 - Pillar compressive strength Extraction ratio .- ----.-... - .....---.__ h 0.0 "'1"'1"'1"'1"'1"111.11.1.111 ...
393 5 0.60 ._ p 0.70 ._ c c 3 0.40 0.30 - 0.20 - 0.10 - 0.00 - ...
394 Use these values together with the Hoek-Brown criterion, =-+ rn-++, cc e3 cc E- to determine the maximal vertical stress t ...
395 I I I (where mi is the value of m for intact rock) and substituting a1 = 110 MPa, a3 = 4 MPa and s = 1, we find that I ,____ ...
396 and at the centre it is ocentre 18.8 ffp 7.7 Fcentre = - - - -- - 2.44 This shows that the effect of the confinement offered ...
Additional points 397 The vertical stress is Overtical = y. z = 0.029 x 800 = 23.2 MPa and hence the ratio of horizontal to vert ...
(9) Is the groundwater understood at the site? Is groundwater likely to (10) Are there any significant anisotropic and/or inhomo ...
Part B: Questions only The Questions in Part A are reproduced here without the answers for those who wish to attempt the questio ...
...
Questions 1.1 -1.5: introduction Q 1. 1 Define the following terms: 0 rock mechanics; 0 engineering rock mechanics; 0 rock engin ...
«
16
17
18
19
20
21
22
23
24
25
»
Free download pdf