›› 2016, Vol. 37 ›› Issue (S1): 651-658.doi: 10.16285/j.rsm.2016.S1.086

• Testing Technology • Previous Articles     Next Articles

Application of needle penetrometer to soft rock strength test

LI Zhi-gang1, XU Guang-li1,2, YUAN Jie1, HUANG Peng1, ZHAO Xin3, FU Yong-peng3, SU Chang4   

  1. 1. Faculty of Engineering, China University of Geosciences, Wuhan, Hubei 430074, China; 2. Institute of Geological Survey, China University of Geosciences, Wuhan, Hubei 430074, China; 3. Geological Survey Center in Wuhan, China Geological Survey, Wuhan Hubei 430250, China; 4. Hubei Institute of Hydrogeology and Engineering Geology, Jingzhou, Hubei 434020, China
  • Received:2015-08-03 Online:2016-06-16 Published:2018-06-09
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (41472263) and China Geological Survey (12120114038701).

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Abstract: How to get the uniaxial compressive strength value of soft rocks is always a problem in engineering because of their low strength, loose structure and difficult processing. Needle penetrometer invented by Japanese, can be used to calculate compressive strength of soft rocks indirectly by testing its needle penetration index (NPI). The paper introduces experimental instrument, operating procedures, announcements and data processing methods of needle penetration test(NPT). Then the strengths of different soft rocks are tested by needle penetrometer in situ and laboratory. According to statistical analysis of test results, the discreteness of sampled value is closely related to rock uniformity and structural discontinuous surface. Finally, contrast methods of NPT and point load test on a set of soft rock samples. It turns out that the results based on these two methods are similar. Therefore, NPT is reasonable and feasible in soft rock strength test and it can be popularized and applied to the soft rock engineering in China.

Key words: soft rocks, needle penetrometer, needle penetration test(NPT), point load test(PLT), uniaxial compressive strength

CLC Number: 

  • TU 452
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