. Railway maintenance engineering, with notes on construction . m 45,500 8^81718f (N 12 trap rock26 loam 18 trap rock19 loam 24 trap rock14 loam 49,932 81 9t 9i llf 1-H ii afl 8 trap rock27 bad clay 8 trap rock27 sandyloam 8 trap rock12 cinder15 bad clay 81,600 lOA lOf98i < 6 n -1 Material inBox No. 1 Box No. 2 Box No. 3 No. of roundtrips Settlement:Box No. 1Box No. 2Box No. 3 Rainfall BALLAST 189 the distribution of pressure through gravel; but under dy-namic loading where the material is subjected to shocks thiswould seem to be absent, and the greatest intensity of pressureoccurs immediat
. Railway maintenance engineering, with notes on construction . m 45,500 8^81718f (N 12 trap rock26 loam 18 trap rock19 loam 24 trap rock14 loam 49,932 81 9t 9i llf 1-H ii afl 8 trap rock27 bad clay 8 trap rock27 sandyloam 8 trap rock12 cinder15 bad clay 81,600 lOA lOf98i < 6 n -1 Material inBox No. 1 Box No. 2 Box No. 3 No. of roundtrips Settlement:Box No. 1Box No. 2Box No. 3 Rainfall BALLAST 189 the distribution of pressure through gravel; but under dy-namic loading where the material is subjected to shocks thiswould seem to be absent, and the greatest intensity of pressureoccurs immediately under the point of application of load. Fig. 110 illustrates the distribution of pressure in dry sand asdetermined by Moyer.* The sudden bends in these curves whichoccur as the eccentricity of the load increases for depths of sandless than 12 ins. in Fig. A and 24 ins. in Fig. B appear to indicatea certain critical depth for different pressures that would be .100 t -73 4= cO 3 80 60 40 20 Loads Varied from SO to ZOO on Area 6xeWeighing Area 6^6. Loads Varied from 1000 to. Applied on Area 12 k 12 / Weighing Area 12 xlZ f^ 54001b. / K 24 sv^«?- m^ ^ f ZO 10 10 5 0 5 10 15 15 10 5 0 5 Eccentricity of Load in Inches. Eccentricity of Load in Inches. A B Fig. 110.—Moyers Tests on Distribution of Pressure through Sand 15 proper to use in obtaining uniform distribution on the roadbedthrough the sub-ballast. It should be observed that these testswere made with dry sand and that probably a very great differ-ence in distributing power would be found for different degreesof dampness. The American Railway Engineering Association recommendsthe following for the proper depth of ballast, f From the data available, it is concluded that with ties 7 in. by 9 8| ft., spaced approximately 24 in. to in., center to center, a depth ♦Engineering Record, May 30, 1914, p. Supplement to Manual, 1912, p. 7. 190 RAILWAY MAINTENANCE of 24 in. of stone ballast is necessary
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1915
