Effect of Amplitude and Confining Pressure on Granite Failure under Ultrahigh Frequency (UHF) Impact Based on Radiation Temperature: Ultrahigh frequency impact technology has great potential to break hard rocks with lower energy consumption. Based on the infrared nondestructive testing technology, the effects of load (i.e., amplitude) and boundary (i.e., confining pressure) conditions on granite damage under ultrahigh frequency impact have been investigated to promote the application of this technology in rock engineering. Experimental results demonstrate that the evolution law of the maximum radiation temperature on granite surface reflects the granite damage state. Under ultrahigh impact, granite specimens are damaged effectively with the impact amplitude exceeding 32μm, and the failure mode of the specimen is changed by the confining pressure. Depending on Griffiths theory, the extension angle of the fatigue crack changes from 60 to 30 degrees with increasing confining pressure. And the transverse fracture occurs in the upper part of the specimen under ultrahigh frequency impact subjected to confining pressure. This research determines the amplitude threshold of the ultrahigh frequency impact load and verifies the effectiveness of ultrahigh frequency impact technology for granite failure subjected to confining pressure.

Expansion screen pipe is a new sand control completion technology. In this paper, the optimization design of the slotted structure of the screen pipe is studied. Mechanical models for both seamless base pipes and slotted base pipes have been established based on elastic-plastic mechanics. The finite element simulation analysis of the expansion process of screen pipes with different slotted structures is carried out, and the relationship among the length of the slot L, the number of slots N, the internal pressure P and the maximum stress at the slot end σ is obtained. The principle and optimization process of the NSGA-II algorithm are introduced. Furthermore, a multi-objective optimization model is formulated, taking P and σ as the objective functions, and the NSGA-II algorithm is applied to optimize this model. By analyzing the obtained optimization results for the screen pipe with an outer diameter of 68 mm, the optimal slotting parameters are L = 137 mm and n = 12. For the optimal slotted structure obtained, P is greater than the minimum expansion initiation pressure, and σ is less than the ultimate tensile strength, which indicates that the optimal solution meets the requirements of both theoretical analysis and engineering practice. In this paper, the NSGA-II multi-objective optimization algorithm is introduced into screen pipe structure optimization for the first time. The structural optimization method of expandable screen pipe proposed in this paper improves the design level and efficiency of the screen pipe. At the same time, it provides a new means for research on screen pipe structures in the fields of petroleum and exploration.

Horizontal drilling of boreholes using complex-strata drilling and multi-stage reaming technologies has gained greater significance in water investigations, as vertical drilling often fails to fully characterise laterally distributed seepage pathways, weak interlayers, fractures, karst formations, and structurally controlled defects. The review explores the geology, drilling principles, major equipment systems, fluid and cuttings transport systems, borehole stability problems, and multi-stage reaming techniques for constructing horizontal boreholes in complex strata. Close consideration is given to the interplay among lithological heterogeneity, structural discontinuities, groundwater conditions, and operational parameters on drilling performance and borehole quality. The discussion demonstrates that multi-stage reaming is not merely a borehole enlargement process but a formation-adaptive design process to enhance the ultimate usability of the borehole and minimise the risk of instability throughout construction. Common engineering uses in the foundations of dams, reservoir banks, underground hydraulic structures, and post-treatment checking are also covered, along with evaluation criteria that include trajectory control, wall integrity, process stability, and reliability of the investigation. The review also lists existing constraints, such as a lack of standardisation, a lack of integration between geology and drilling control, and excessive reliance on experience-based design in heterogeneous formations. The further development should focus on intelligent drilling, real-time interpretation of responses, process optimisation using digital twins, and integrated investigation systems. The article is systematically presented as a source for the development of horizontal-borehole construction and staged-enlargement technologies in more challenging landscapes in water-conservancy engineering.