Development of an Improved Point Load Apparatus

개량형 점하중강도시험기의 개발

  • 김용필 (울산과학대학 공간디자인학부) ;
  • 엄정기 (부경대학교 에너지자원공학과)
  • Published : 2009.12.31


The accuracy of point load apparatus is depend on point to point coaxial fitting. Also, the estimation of applied point load using the pressure gauge frequently lead to erroneous results. An improved point load apparatus has been developed in this study by mounting linear bearing on polished support rod, and eccentric error of point to point axis has been sustained less than 0.1 mm even under series of extreme work load conditions. Two digital displacement gauges are attached to measure the distance from point to point with sample specimen. A load cell mounted at the end of upper conical platen measure the applied net load on sample instead of preassure gauge. Total of 107 point load tests has been achieved to assure the quality and performance of developed apparatus. This exercise turned out to be successful.


point load apparatus;rock strength


  1. ASTM D 5731-95, Standard test method for determination of the point load strength index of rock, American Society for Testing and Materials
  2. Reichmuth, D.R., 1968, Point load testing of brittle materials to determine tensile strength and relative brittleness, Proc. 9th US Symp. Rock Mechanics, pp. 134-159
  3. Turk, N. and W.R. Dearman, 1985, Improvements in the determination of point load strength, Bull. Int. Ass. Engg. Geol., 31, pp. 137-142
  4. 한국암반공학회, 2007, 암석의 점하중강도 표준시험법, 터널과 지하공간(한국암반공학회지), 17, pp. 75-82
  5. Brook, W.F., 1977, A method of overcoming both shape and size effects in point load testing, Proc. Conf. Rock Engg., Newcastle University, pp. 53-70
  6. Forster, I.R., 1983, The influence of core sample geometry on the axial point load test, Int. J. Rock Mech. Min Sci. & Geomech. Abstr., 20, pp. 291-295
  7. Norbury, D.R., 1986, The point load test, In Site Investigation Practice: Assessing BS 5930, Engineering Geology special Publication, 2, A.B. Hawkins (ed.), Geological Society, London, pp. 326-329
  8. Broch, E. and J.A. Franklin, 1972, The point load strength test, Int. J. Rock Mech. Min. Sci., 9, pp. 669-697
  9. Bieniawski, Z.T., 1975, The point load test in geotechnical practice, Engg Geol, 9, pp. 1-11
  10. Hassani, F.P., M.J. Scoble and B.N. Whittacker, 1980, Application of the point load index test to strngth determination of rock and proposals for a new size correction chart, Proc. 21st US Symp. Rock Mechanics, Rolla, pp. 543-553