论文部分内容阅读
为了更为准确地测定岩石的抗拉强度以降低钻杆式水压致裂原地应力系统柔性对最大水平主应力计算的影响,研发了多直径岩芯液压致裂岩石抗拉强度快速试验机。试验机参照水压致裂测试力学过程,基于岩石厚壁筒原理研发,主要核心部件包括加载系统、压力监测和数据采集系统、样品夹持系统3个部分。为了方便推广该套试验设备和此类试验方法,针对试验影响因素加压速率、中心盲孔深度和直径、空心岩柱内外径之比等因素开展了57个岩石样品的试验工作。试验结果显示,空心岩柱盲孔深度对测试结果影响不明显,但是会影响测试成功率,岩样盲孔深度可为岩柱高度的0.7~0.8倍。空心岩柱中心孔直径会显著影响测试结果,当中心孔直径大于20 mm时,中心孔的尺寸效应不再显著。如果考虑空心岩柱内外径之比,根据理论分析和试验数据可知,取0.3~0.5可获得更为稳定的测试数据。试验采用的加压速率为0.02 MPa/s,获得试验数据稳定可靠。此次测试样品福建长汀下古生界奥陶~志留系板岩的岩石抗拉强度平均值为8.4 MPa。这些认识为后续规范地开展此类测试奠定了初步基础。
In order to determine the tensile strength of rock more accurately and reduce the influence of drill pipe hydraulic stress in-situ stress system on the calculation of the maximum horizontal principal stress, a multi-diameter rock hydraulic cracked rock tensile strength rapid testing machine . The testing machine is based on the hydraulic fracturing test mechanics process and is developed based on the rock thick wall cylinder principle. The main core components include loading system, pressure monitoring and data acquisition system and sample holding system. In order to facilitate the popularization of the set of test equipment and such test methods, 57 rock samples were tested in accordance with factors such as the rate of pressurization of the test factors, the depth and diameter of the blind hole in the center, the ratio of the internal and external diameters of the hollow column. The test results show that the blind hole depth of hollow pillars has no obvious effect on the test results, but it will affect the test success rate. The blind hole depth of rock samples can be 0.7 ~ 0.8 times of the rock pillar height. Hollow pillar center hole diameter will significantly affect the test results, when the center hole diameter is greater than 20 mm, the size of the center hole effect is no longer significant. If we consider the ratio of hollow rock column inner diameter and outer diameter, according to the theoretical analysis and experimental data, we can see that 0.3 ~ 0.5 can get more stable test data. The pressure rate used in the experiment was 0.02 MPa / s, and the test data obtained was stable and reliable. The test sample of Changting, Fujian Lower Paleozoic Ordovician ~ Silurian slate rock tensile strength average of 8.4 MPa. These understandings laid the preliminary foundation for the subsequent normative conduct of such tests.