Laserfiche WebLink
as poles in rock slope studies. However, dip vectors are rapidly <br />gaining recognition as being easier to plat and interpret <br />(Whisonant and Watts, 1989). Figure 3 is a pole plot of data from <br />a site in the Appalachian Mountains of Virginia. The poles have <br />been grouped into clusters by eye and numbered for identification. <br />Figure 4 is a dip vector representation of the same data. Note the <br />differences in appearance of the clusters between the two plots. <br />Discontinuity clusters Iota ,,. ot° <br />are not always easy to 0 20 ~ ~ ~ <br />identify by eye on a to so x ~° <br />p l o t h e n c e <br />orientation data are to <br />sometimes contoured to <br />20 <br />make groupings more a <br />obvious. A number of so <br />techniques exist for ~~ 2 _ _ <br />contouring orientation eo <br />data and the reader ee ~ <br /> <br />may wish to refer to <br />,°O3 _ <br /> <br />l <br />Chapter 3 in Hoek and ~ ? i? ~~ <br />I <br />Bray (1981) for so z +....-~ <br />additional details. 03 _ zx r <br />Mast procedures ~ ` I <br />involve the placement es <br />of a counting cell, or is <br />a net of counting <br />cells, over the eo <br />stereoplot and So <br />determining the number ~~ <br />of discontinuities 'O <br />_~ <br />3 <br />that fall within the so <br />counting cells at p . <br />different positions on le <br />the plot. The l~ <br />resultin o ulation o <br />:~_ - <br />.:..~ - <br />.+r..i <br />g P p too zoo 2z° zw zro zeo soo szo sro sr° <br />density values then fao zta uo r_o ao zoo slo r_o s3o <br />replace the platted <br />point s o n t h e KEYI OS+cmtlrulti°+ +.r C~untinp M+. <br />5tereonet. Portions s co to - axl tt c° 1. • <«I > u - n+l <br />of the plot having <br />large numbers of Figure 5. Computer contoured rectangular <br />discontinuities per Plot of data from Cedar Bluff, Virginia. <br />unit area are <br />therefore emphasized by large density values. Figure 5 illustrates <br />data from Cedar Bluff, computer contoured in a rectangular plot <br />format. The top half represents dip directions of 0° to 180° while <br />the bottom half represents dip directions of 180° to 360°. Dip <br />values are read along the side. Figure 6 is a projection of the <br />contours from the rectangular plot to an equal-area pole plot. <br />The importance of discontinuity clustering can be seen in Figure <br />7. Spatial relationships between discontinuity clusters and the <br />slope face determine what types of failures are possible. The <br />Stereonet Analyses 6 ~ Appendix A <br />roR-~ N <br />APPkoVE~ 3~zv~ay <br />OSr+c.Sen) <br />Soo 120 lb I60 1[i0 <br />lto tso tw too <br />n <br />U <br />s <br />• <br />