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Abstract The bolted and unbolted jointed rock mass specimens with cross-cracks were simulated by similar materials. The angles between the primary cracks and the secondary cracks，the positions of the bolts and the angles between the bolts and the loading directions were taken as the control parameters of the specimens leading to the total of 32 groups of specimens of similar material be produced. The uniaxial compression tests of the specimens were carried out to obtain the bolting effect and the failure modes of the jointed rock masses with cross-cracks. The test results showed that：(1) The strengths of the specimen reached the maximum values if the bolting position was above or under the crossing points of the cross-cracks for the group of specimens with the same angle between the primary and secondary cracks. When the bolting position went through the crossing points of the cross-cracks，the strengths of the specimens did not reach the maximum values but its after peak values were stable. (2) The majority peak strength values of the bolted rock masses with joints and cross-cracks are higher than those of the ones with a single crack. (3) The angles between the primary and the secondary cracks affected the mechanical properties of jointed rock masses with bolting. The jointed rock mass had the best bolting effect when the angle between the primary crack and the secondary crack was about 30°. (4) The bolt increased the ability of the jointed rock mass to resist the cross-crack propagation and reduced the possibility of jointed rock masses to a sudden failure.
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Received: 22 November 2013
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2014, Vol. 33 
