Study on Quick Test Method of Rock Hardness Index During Tunnel Construction

Rock hardness is one of the basic factors to determine rock mass quality in the code, and it is required to use rock saturated uniaxial compressive strength as a quantitative index, which is also a difficult problem to obtain quickly in the field. Based on the demand for rapid determination of surrounding rock grade during tunnel construction, the operability of routine test and alternative method of rock saturated uniaxial compressive strength during tunnel construction is analyzed, and the Richter hardness is introduced as an alternative index. Through the water immersion free water absorption test and hardness test of rock samples, the macro evaluation of water absorption and softening characteristics, related to determining the grade of surrounding rock related to determining the grade of surrounding rock, is carried out, and the correction for waterlogged rock hardness were proposed. Besides, the alternative relationship between Richter hardness and rock saturated uniaxial compressive strength is obtained from the statistics of a large number of rock sample strength and hardness test data. Finally, a set of scientific, reliable and convenient new methods for evaluating rock hardness are formed, which lays a key technical foundation for rapid classification of surrounding rock during tunnel construction and research and development of equipment system. it can accordingly provide support for tunnel information design and construction.