超深钻岩芯地质环境真三轴试验装置研制及应用

Development and application of an ultra-deep drilling core geological environment true triaxial apparatus

为研究超深部岩芯的变形与破裂行为,研制了超深钻岩芯地质环境真三轴试验装置。该装置主要用于测试超深钻岩芯加工的试样(25 mm×25 mm×50 mm)在真三轴应力下的全应力-应变行为、循环加卸载破裂行为和时效变形行为,解决了试样变形测量不准确、加载系统低刚度、高油压与作动器压力互相干涉等技术难题。利用该装置完成了山东黄金集团三山岛金矿西岭副井工勘孔岩芯真三轴应力下力学行为的测试,发现:循环加卸载弱化了试样的脆性破裂特征,诱导3个方向的变形表现出各向异性;分级蠕变试验中,试样3个方向的变形均表现出初始蠕变、稳态蠕变、加速蠕变,且3个方向的蠕变速率均随偏应力的增加近似线性增加。

To study the deformation and fracture behavior of ultra-deep drilling core,an ultra-deep drilling core geological environment true triaxial apparatus was developed.The apparatus was mainly designed to obtain the complete stress-strain behavior,cyclic loading and unloading fracture behavior,and time-dependent deformation behavior of specimens(25 mmx25 mmx50 mm)processed by ultra-deep drilling cores under a true triaxial stress,mainly solving the technical problems such as inaccurate measurement of specimen deformation,low stiffness of the apparatus,mutual interference between pressure chamber oil pressure and actuator pressure.The device was used to test the mechanical behavior of the cores from the Xiling engineering exploration hole at the Sanshandao Gold Mine of Shandong Gold Group under the true triaxial stress.It was found that the true triaxial cyclic loading and unloading weakened the brittle fracture characteristics of the specimen,and induced deformation in three directions to show anisotropy.In the multi-stage true triaxial creep test,the deformation of specimen in three directions showed primary creep,steady creep,and accelerated creep.The creep strain rates in the three directions increased approximately linearly with deviatoric stress.