温度损伤大理岩不同含水条件下的动态压缩特性研究

Dynamic compression strength of thermal damaged Fangshan marble on dry and saturated conditions

深部岩石工程围岩处于三高一扰动的复杂地质环境,岩石的力学性质表现出与浅部岩石不同的特征。因此研究温度损伤后岩石在不同含水条件下动态压缩特性在岩石工程中具有重要意义。研究选取均质的细颗粒房山大理岩,利用自主研发的50 mm直径的分离式霍普金森杆压杆(split Hopkinson pressure bar,SHPB)系统,进行4种温度(25℃,105℃,450℃,700℃)损伤梯度下,干燥和饱水2种状态的单轴动态压缩加载试验;研究小孔隙率岩石温–水作用下的动态压缩特性。研究结果表明:随着温度的增加,大理岩的纵波波速均呈先上升后下降趋势,超过450℃时下降幅度明显;在试验所得加载率范围内,每级温度载荷下大理岩的动态压缩强度均有明显的率相关性,且和室温相比其他温度下岩石动态强度随着加载率的增加更加明显;当加载率一定时,温度损伤后干燥状态的岩石动态抗压强度随着温度的升高呈现明显的下降趋势,饱水状态的岩石呈现同样的变化趋势。经过105℃处理的损伤岩石,饱水和干燥状态下动态压缩强度近乎一致,而在450℃条件下,饱和岩石的动态压缩强度比干燥条件岩石的动态强度有所增加,压缩强度存在饱水强化现象,在700℃条件下,损伤岩石的饱水强化现象更加明显,并在高加载率下(加载率大于1500GPa/s),随着加载率的增加饱水大理岩动态强度增加较干燥大理岩更快。

Deep rock engineering is in a high stress disturbance environment,and high temperature must be taken into consideration,dynamic compression characteristics are important for evaluating the stability of surrounding rock,which is different from the shallow. In order to get the dynamic mechanical properties of rock suffered both temperature and water. By using the system of Hopkinson pressure bar,dynamic uniaxial compression tests of Fangshan marble in dry and saturated conditions are carried out in four temperature gradients(25 ℃,105 ℃,450 ℃,700 ℃). The dynamic compression characteristics of small porosity rock under the action of temperature and water are studied. The results show that the longitudinal wave velocity increases at first and then decreases,and starts decline sharply after 450 ℃. The dynamic uniaxial compression strength of dry and saturated marble gradually increases linearly with the increases of loading rate in every temperature,and rock after temperature damage is more obvious than room temperature. Compression strength of thermal damaged rock assumes a downward trend as the temperature increases. The compression strength of saturated specimens is almost same as dry specimens in 105 ℃,and the dynamic compressive strength of saturated rock is higher than that of dry rock at 450 ℃,while the strength of saturated specimens can be higher than dry ones when loading rate(after 1 500 GPa/s) is high enough in 700 ℃.