Experimental Study on Creep Characteristics of Coal under Uniaxial Compression

Generally surrounding rocks of deep mine show the typical creep characteristics and the multi stage loading creep test of coal was carried out by MTS815 rock mechanical test system in this paper. Compared to the creep coefficient of other rocks, creep coefficient of coal is relatively small. Coal creep failure changes obviously when load level is higher than the threshold stress. The constitutive characteristics of creep failure of coal can be fitted preferably by the Cubic Polynomial.

Analysis on Bolt Supporting Mechanism for Roadways Driving along next Goaf Based on Triaxial Compression Test

Conventional triaxial compression tests of coal specimens are carried out by MTS815 servo-controlled rock mechanical test system, and the strength and deformation characteristics of coal under different confining pressure are analyzed. On that basis, bolt supporting mechanism of surrounding rocks of roadways driving along next goaf is studied.

Borehole Stability Analysis and its Application in Xujiahe Formation of ZJ Block

The mainly borehole problems are sticking (collapse) and circulation loss in Xujiahe formation of ZJ block, so the drilling rate is very low. In order to improve the penetration of rate of ZJ block, the rock mechanical test method, ground stress test method, well history statistics method, and logging data analysis method were adopted. The borehole stability mechanism of xujiahe formation was analyzed. Combined with the drilling fluid experimental evaluation, the measures of improve wellbore stability of xujiahe formation was Proposed. Field application tests show that, the borehole problems and its processing time are greatly reduced using those proposed measures. The penetration of rate in the Xujiahe formation of test well increased 20-30%, and the application effect is obvious.