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Abstract Because of the deficiency of uniaxial compression intensity testing and failure law on micro rock-samples，a testing machine for micro sample f 5 mm×10 mm has been designed in order to study fractures extending or breakage mechanism during the rock and coal samples under uniaxial compression. The machine is mostly composed of prestressing equipment，primary loading stress equipment，sample room and hydraulic pressure transmission equipment. There are several advantages compared with typical or ordinary testing machine：(1) During the loading process of rock and coal samples and coupling with three-dimension microscope CT，emergence and development of inner fractures and cracks have been observed. (2) Curves of complete stress-strain which are similar with ordinary curves have been drawn，using size-scale effects coefficient for calculating and obtaining the uniaxial compression intensity in others size of samples. Beyond these curves，four phases of micro samples under compression have been reflected faithfully during the whole testing course. (3) Compared with the former numerical simulation of rock testing，the same and different aspects have been analyzed；and the conclusion is used for deeper interrelated theories. In order to get more applications，in the future the machine¢s each part will be perfected：not only the operational characteristics will be enhanced，but also the loading values will be leveled up，so as to test the higher intensity rock-samples. The elementary testing results are proved that the experimental study is scientific and feasible. The development of this testing machine will improve the investigations on fracture law and the development of rock mechanics to which ordinary and large-scale machines could not implement.
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Received: 25 February 2010
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