Deformation properties and seepage characteristics of broken rock under the water saturation state is always the great subject during the deep mining. Broken rock shows significantly creep properties. Creep behavior caused the continuous variation of pore as well as the seepage characteristics. The change law of pore of saturated broken shale during creep process is studied through a experimental device for multiphase coupling and creep of broken rocks. The effect of axial stress and grain size on the porosity is analyzed. The results show that in the broken shale's creep process the porosity is negative exponent linear dependence relation with time n = n0 + a e- bt, there n is the porosity of granular shale, t is time, n0 is the porosity at the stabilization phase, a ,b are the Regression coefficient, and n0 , a , b are decided by the particle size and the load, and the whole process has obvious stage: when the load is same, the smaller the crushing shale's particle, the smaller the change of its porosity, and then the porosity is larger in the end when the process is stable. As the load increasing, the difference of the porosity caused by the different crushing shale's particle dimension becomes smaller and smaller; in the same shale's particle dimension, one with larger load has a quicker change of porosity than the small ones. In the initial period stage of creep, the particles are easy to slide because of bad balance between the granular shale, and the porosity of every particle sizes rock sample reduces quickly; When after a period of time, the amount of particles broken increase, more and more fine particle have filled the pore between broken rocks, the granular shale become more denser, the porosity reduces slowly, then tends some stable value finally.
With the depth of coal resources exploitation growing, surrounding rock-mass in deep engineering presents the characteristics of high stress, rapid time weighting, large deformation, long duration, reacting with water easily disintegrating and dramatic decrease of the strength. Large deformation problems are being increasingly prominent, too. The moisture state of broken rock is a important factor of affecting its properties of rock creep. With the time going, loose rock mass easily becomes unstable, leading to catastrophic failures [1]. LI Huamin[5], who does the research of the creep characteristics of marble and ZHANG Zhongting, LUO Jujian[3] study the creep characteristics of rock under multi-stage loading, and through comparing the result of creep test in dry and inwatersaturated condition, ZHU Hehua, YE Bin [2] study the law of the creep characteristics influenced by waterbearing condition. Triaxial creep test is done by Step Method by LIU Jianzhong, YANG Chunhe, and numerical simulation is done by WANG Yongyan [1] to research the process of creep failure of surrounding rock of different depth in deep engineering. To the time effect of broken rock deformation, it is now mainly focused on creep test in dry condition and creep characteristics analysis.
