不同轴向静压下硬岩受频繁动力冲击作用下的力学特性研究

为了研究在不同轴向静压条件下硬岩受频繁动力冲击作用下的力学特性,对取自冬瓜山铜矿深部(900m)的矽卡岩试样进行动力冲击试验。试验结果表明:轴向静压对岩石累积冲击次数影响显著,累积冲击次数与轴向静压呈二次函数下降关系。随着冲击次数的增加,弹模整体呈下降趋势,不同轴向静压下,弹模随冲击次数表现出不同的变化特征;随着冲击次数的增加,峰值应力整体呈降低趋势,轴向静压对峰值应力的影响显著。不同轴向静压下,试样随冲击次数表现出不同的能量耗散规律,当轴向静压为75MPa时,试样出现了吸收能量的现象;当轴向静压为85 MPa和100 MPa时,试样在冲击作用下始终为释放能量,说明在高应力作用下,储存在试样内部的弹性应变能已经能够完全提供试样发生破坏所需要的能量,此时,岩石在动力扰动的诱导作用下极易发生破坏。这一现象为揭示深井开采过程中的岩爆发生机制提供了依据。

Mechanical Properties Study of Hard Rock with Frequent Dynamic Impact under Different Axial Static Pressure

In order to study the mechanical properties of hard rock with frequent dynamic impact under different axial static pressure conditions, the dynamic impact test was carried out on skarn samples which were taken from the deep (900m) of Dongguashan copper mine. The test results showed that the axial static pressure had a significant effect on the cumulative number of impacts on the rock,the cumulative impact times and the axial static pressure had a quadratic function. With the increase of the number of impacts, the elastic modulus was decreased. The elastic mode showed different variation characteristics with the number of impacts under different axial static pressures. The peak stress decreased with the number of impacts increases and the axial static pressure has a significant influence on the peak stress. The samples showed different energy dissipation laws under different axial static pressures. The samples appeared to absorb energy when the axial static pressure was 75MPa.The samples always releaseed energy under impact when the axial static pressure was 85MPa and 100MPa. The elastic strain energy stored inside the specimen can fully provide the energy required for the specimen to be destroyed under high stress. The rock was easily destroyed under the induction of dynamic disturbance,and this phenomenon provided a basis for revealing the mechanism of rockburst in deep mining.