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中文摘要：
为了研究预静载条件下硬岩受动力扰动的断裂特性变化规律，采用大理岩制作中心直裂纹半圆盘（semicircular bend，SCB）三点弯曲试样，在MTS Landmark电液伺服试验机上，进行预静载下的循环加卸载和不同扰动频率的岩石断裂韧度测试试验，发现硬岩断裂的增韧和减韧效应。在获得岩石静载断裂载荷的基础上，设定预静载上限为常规静载断裂载荷值的90%，首先进行循环加卸载试验，循环加载次数分别为5，10，20，40，80，100和167次；然后进行不同扰动频率下预静载岩石的断裂韧度测试试验，采用半正弦波动力扰动加载方式，波动幅值为10%静载断裂载荷值，加载频率分别为1，10，20和30 Hz。研究结果发现：（1）随着循环次数的增加， SCB试样断裂韧度显著增加（循环40次为最高点，增加幅度为常规断裂韧度的19%），然后逐渐减小并收敛于定值（大约循环80次数后趋于收敛，最后的增加幅度为常规断裂韧度的11%），整体趋势具有增韧效应；（2）在动力扰动条件下，岩石断裂韧度值较常规条件下有较大幅度减小（1 Hz频率下减小幅度为常规断裂韧度的9%），并且随着扰动频率的增加，岩石断裂韧度呈线性减小的趋势，整体趋势具有减韧效应。因此，在预静载为常规静载断裂载荷值90%条件下，循环加卸载只会增加岩石的断裂难度，高频扰动却有利于岩石的断裂破坏。上述研究规律为深部硬岩非爆破连续开采提供了一定的理论启示。针对深部高应力硬岩，采用诱导方式适当增加应力集中程度使围岩进入临界破坏阶段，进而开发具有高频振动加载的破岩机械进行采掘，可以在一定程度上提高高应力围岩的破岩效率。
英文摘要：
In order to investigate the variation of fracture characteristics of hard rock under the condition of pre-static loading with dynamic disturbance,the semi-circular bend（SCB） marble specimens with central straight cracks were tested with the MTS Landmark electro-hydraulic servo testing machine under cyclic loading and unloading with different high disturbance frequencies. The effects of toughness increasing and decreasing of the hard rock fracturing were discovered. The value of 90% of the conventional static fracture load was set as the upper limit of the pre-static load. The cyclic loading and unloading tests were performed with the loading cycles of 5,10,20,40,80,100 and 167,respectively. The dynamic disturbance tests with different frequencies under pre-static load were conducted by using the semi-sine loading wave and the value of 10% of the conventional static fracture load was set as the amplitude of loading fluctuation and the loading frequency was 1,10,20 and 30 Hz, respectively. It was found that with the increase of the loading cycles,the fracture toughness of SCB specimen increased significantly firstly. The fracture toughness reached the highest value at the loading cycles of 40 with an increase of 19%compared with the conventional fracture toughness. Then,it gradually decreased and reached a stable value at the loading cycles of 80 with an increase of 11% compared with the conventional fracture toughness. Overall it exhibited a toughness-increasing effect. Under the condition of dynamic disturbance,rock fracture toughness values were reduced greatly compared to that of the normal condition. For example,when the loading frequency was 1 Hz,the rate of decrease was 9%compared with the conventional fracture toughness. The rock fracture toughness decreased linearly with the increase of the disturbance frequency. In conclusion,under the conditions with pre-static load（90% of conventional static fracture load）,cyclic loading and unloading can increase the fracture toughness of hard rock. While the f
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