Storage rooms, water treatmen t plants, minor road and railwa y tunnels, surge chambers, acces s tunnels. Be the first to add this to a list. Principal stress distributions in a rib pillar defined b y a ratio of pillar height to pillar width of 2.
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Auerase pilier stresse s Figures 50 illustrates a typical square room and pilla r Layout used in mining horizontally bedded deposi ts o f materials such as cool.
Gypsum fillings may behave the Sam e way. Changes i n the shape of the excavations and repositioning the excavations with respect to one another is of grea t assistance in overcoming these problems but suppor t may also be required.
The student resources previously accessed via GarlandScience. Not e that the average value of the maximum principal stress c l across the orck must be equal to the average pillar stres s e r, in order to satisfy the conditions of equilibrium in th e model.
Swelling clay may cause serious problems through fre e swell and consequent lass of strength, or through considerable swelling pressure when confined.
UNDERGROUND EXCAVATIONS IN ROCK
This trend is not surprisin g since, as will be shown in the next chapter, rock is incap able of supporting very high stresses when there are larg e differentes in the magnitudes of the broqn applied principa l stresses. On the functional classification of rocks fo r en g ineering purposes.
Consequently, the most usefu l plot of the stresses surrounding an underground opening i s a plot of the principal stress contours such as that reproduced in figure Index properties for intact rock. Instability due to adverse structural g eology tend s to occur in hard rocks which are faulted and jointe d and where several sets of discontinuities are steepl y inclined. Uniaxial compressive strength of intact rockSpacing of joints and bedding4.
Isometric drawing chart s 44 9 Appendix 3: Dominant materia l in gouge Potential behaviour of gouge materia l: The detaile d design of support for underground excavations, including th e use or rock mass classifications to assist in the choice o f support systems, will be discussed in chapter 8 of this book.
As Hesults of in sitze stress measurement s During the past twenty years, several techniques for in sit u stress measurement have been developed and have been use d Figure Thi s is a Jong term stability and sometimes fluid flow problem which can easily be overlooked during deslg n and construction.
General Report on These This is known as a spaZZing condition.
Hoek,Brown Underground Excavation in Rock - Free Download PDF
The regional geolo g y The structural geological conditions which occur on an y particular sitz andd a p roduct of the geological histor y of the surrounding region. Hence, if very high horizontal stresses existe d at depths in excess of 1 kilometre, these would have induce d fracturing, excavationd flow and time-dependent deformation i n the rock, and all of these processes would tend to reduc e the difference between horizontal and vertical stresses.
From Table 6, this situation is described as unfavourable for which a rating adjust ment of is obtained from Table 5B.
Public Private login e. Rock TunneZling with Steel Sup p orts.
Recent excavatins with the Q-sys tem of tunne l support design. Then set up a personal list of libraries from your profile page by clicking on your user name at the top right of any screen. In situ stresses For stress Fields other than hydrostatic k 1th e lowest boundary stresses will be associated with an opening of ovaloidal shape. F Underground nuclear power stations, railway stationssports and public facilities, underground factories.
Underground excavations in rock / E. Hoek, E.T. Brown. - Version details - Trove
Sometimes, clean ing the exposed surface with a pressurised jet of water o r air is sufficient to reveal the rock mass for the purpos e of structural mapping. Major shaft systems. Rock Mechanics Madrid,pages - Norwegian Geoteehnical Report Mo. Because any form of instability cannot b e tolerated, the resources allocated to the design and installation of support systems are normally adequate andsometimes, even generous.
A is very good broancorresponding to Terzagh i's hard and intact rock, while G is very poor rock which corresponds roughly to Terzaghi' s squeezing or swelling rock. Norwa y Bjornevan, N.