Jonak Józef, Karpiński Robert, Wójcik Andrzej, Siegmund Michał
Department of Machine Design and Mechatronics, Faculty of Mechanical Engineering, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland.
KOMAG Institute of Mining Technology, Pszczyńska 37, 44-100 Gliwice, Poland.
Materials (Basel). 2023 Feb 28;16(5):2010. doi: 10.3390/ma16052010.
Previously published articles on anchors have mainly focused on determining the pullout force of the anchor (depending on the strength parameters of the concrete), the geometric parameters of the anchor head, and the effective anchor depth. The extent (volume) of the so-called failure cone has often addressed as a secondary matter, serving only to approximate the size of the zone of potential failure of the medium in which the anchor is installed. For the authors of these presented research results, from the perspective of evaluating the proposed stripping technology, an important aspect was the determination of the extent and volume of the stripping, as well as the determination of why the defragmentation of the cone of failure favors the removal of the stripping products. Therefore, it is reasonable to conduct research on the proposed topic. Thus far, the authors have shown that the ratio of the radius of the base of the destruction cone to the anchorage depth is significantly larger than in concrete (~1.5) and ranges from 3.9-4.2. The purpose of the presented research was to determine the influence of rock strength parameters on the mechanism of failure cone formation, including, in particular, the potential for defragmentation. The analysis was conducted with the finite element method (FEM) using the ABAQUS program. The scope of the analysis included two categories of rocks, i.e., those with low compressive strength (<100 MPa) and strong rocks (>100 MPa). Due to the limitations of the proposed stripping method, the analysis was conducted for an effective anchoring depth limited to 100 mm. It was shown that for anchorage depths <100 mm, for rocks with high compressive strength (above 100 MPa), there is a tendency to spontaneously generate radial cracks, leading to the fragmentation of the failure zone. The results of the numerical analysis were verified by field tests, yielding convergent results regarding the course of the de-fragmentation mechanism. In conclusion, it was found that in the case of gray sandstones, with strengths of 50-100 MPa, the uniform type of detachment (compact cone of detachment) dominates, but with a much larger radius of the base (a greater extent of detachment on the free surface).
此前发表的关于锚栓的文章主要集中在确定锚栓的拔出力（取决于混凝土的强度参数）、锚头的几何参数以及有效锚固深度。所谓破坏锥的范围（体积）通常被视为次要问题，仅用于近似锚栓安装介质中潜在破坏区域的大小。对于这些研究结果的作者而言，从评估所提出的剥离技术的角度来看，一个重要方面是确定剥离的范围和体积，以及确定破坏锥的破碎为何有利于剥离产物的去除。因此，对所提出的主题进行研究是合理的。到目前为止，作者已经表明，破坏锥底部半径与锚固深度的比值明显大于混凝土中的比值（约为1.5），范围在3.9 - 4.2之间。本研究的目的是确定岩石强度参数对破坏锥形成机制的影响，特别是破碎的可能性。使用ABAQUS程序通过有限元方法（FEM）进行了分析。分析范围包括两类岩石，即抗压强度低（<100 MPa）的岩石和强度高（>100 MPa）的岩石。由于所提出的剥离方法的局限性，分析针对有效锚固深度限制为100 mm的情况进行。结果表明，对于锚固深度<100 mm的情况，对于抗压强度高（高于100 MPa）的岩石，存在自发产生径向裂缝的趋势，导致破坏区域破碎。数值分析结果通过现场试验进行了验证，在破碎机制过程方面得出了一致的结果。总之，研究发现，对于强度为50 - 100 MPa的灰砂岩，均匀类型的分离（紧密分离锥）占主导，但底部半径要大得多（自由表面上的分离范围更大）。
