Firstly the particle distribution of debris of Sanjome andesite produced in uniaxial compression test was studied. Then same tests were performed by using different kinds of rock and their particle distribution were calculated and compared respectively. Furthermore, influences of different test conditions such as specimen size, ends condition and moisture to the particle distribution were Investigated.
It is well known that machine excavated detritus is an important factor in excavation process. Its particle size distribution and shape characteristics is not only useful for estimating rock properties and analyzing rock fracture mechanism, but also helpful for choosing proper haulage/ recycling methods to save Cost and improve working efficiency. In former study (Wenli Chen et al. 2000), the authors investigated the particle size distribution of detritus produced by different excavation methods and found that particle size of detritus changes with fracture degree, but their particle distribution curves were parallel and showed similar change trends. Whether the results of particle distribution obtained from in-situ experiments are suitable for other fragments and realized in more widen range, as the first step, it is essential to analyzing the particle size distribution of debris produced in uniaxial compression test in laboratory. On the other hand. researches on the uniaxial compression test of rock have been carried out intensely over the years. Much of them focused on the rock mechanical properties, testing method and test machine. For example, the common failure mode of rock specimen in uniaxial compression experiments and their physical process (Holzhausen G.R. & Johnson A.M. 1979) were fully studied. While Loading rate dependency of uniaxial compressive strength of rock under water-saturated condition (Okubo et al. 1992) was also discussed. More early, Hudson et al reviewed the development history and working principle of test machine (Hudson et al. 1972) in detail. Besides these. there were still hundreds and thousands of results had been published. Therefore in the pages that follow we will first investigate the particle size distribution of Sanjome andesite debris produced in uniaxial compression test. Then particle size distribution of other kinds of rock were studied and compared. After that, experiments conducted in different test conditions and their results would be reported.
In this study, we investigated particle size distribution of debris in uniaxial compression and the experiments were carried out in the following three steps: Firstly Sanjome andesite was selected as rock material. The specimens used were cylindrical shape with unfinished ends; both diameter and length were 50 mm. After the specimens were airdried in an air-conditioned room, the uniaxial compression test was carried out in a servo-controlled machine (MTS model 3128) with a constant displacement rate (0.0 I mm/s). The compressed displacements were divided into 4 groups, i.e. 20 %, 40 %. 60 % and 80 % of the specimen length (or rather to say 10 mm, 20 mm, 30 mm and 40 mm respectively). While in each group, 4 specimens were compressed under the same conditions.
