Analysis of rock fracture seepage plays an important role in evaluation of rock engineering safety. The three-dimensional coordinate points of the rock fracture surface were scanned by a three-dimensional structure optical scanner and visually reconstructed. Parameters such as joint roughness coefficient JRC and topography statistics were used to quantitatively describe the roughness and undulation characteristics of rock fractures. Through experimental research, it is found that when the seepage pressure gradient increases, the seepage in rock fractures will change from linear seepage to non-linear seepage, and the Forchheimer formula can better fit this process. The threshold and Reynolds number of the critical Darcy flow were obtained by introducing he nonlinear factor E. The relative loss of momentum-Euler number was introduced to study the law of fluid energy evolution in the process of fracture seepage. It is found that the Euler number shows a trend that first drops rapidly and then gradually stabilizes. The result has certain guiding significance for actual engineering.

To explore the microseismic evolution characteristics of instability failure of surrounding rock of deep buried tunnel, biaxial compression tests of granite were carried out under different intermediate principal stresses (σ₂). The microseismic monitoring system and high-definition camera were used to monitor and record the failure of granite in real time. The evolution characteristics of microseismic b value and dominant frequency of rock failure process under different σ₂ conditions were analyzed, and the index of microseismic energy release (MSER) was proposed to describe the degree of rock failure. The results show that with the increase of σ₂, the cumulative microseismic energy release, the maximum value of lgN/b and the ratio of low frequency signal before rock failure, and the microseismic energy release rate at rock failure time all increase, while the minimum value of b value before rock failure decreases. In addition, the microseismic precursor of rock instability lists as follows: b value drops to less than 0.8; lgN/b rises to more than 3; High amplitude and low frequency signal appears. The precursors of rock slabbing are high amplitude low frequency signals accompanied by a small number of high amplitude high frequency signals, while the precursors of rockburst failure are that b value drops to less than 0.5, and lgN/b rises to more than 5, and high amplitude signal only appears in the low frequency band.

To solve the disadvantage of high cost and low efficiency in the traditional three-way crack detection methods, a three-dimensional crack change detection method based on binocular vision was proposed. Three-dimensional equivalent model of crack change was established, and the calculation of crack changes was equivalent to the calculation of changes between targets. Three-dimensional reconstruction of cracks was carried out through feature point code matching, spatial coordinate system transformation, three-dimensional coordinate calculation, and the three-dimensional situation of the fracture change was obtained. To verify the accuracy of the method, a unidirectional displacement test was carried out. The results show that the maximum measurement error of the opening and dislocation of the crack is within 0.2 mm, and the maximum measurement absolute error of settlement of the crack is within 0.3 mm, which meets the requirements for crack detection in technical specification for earth-rockfill dam safety monitoring.

The internal defects of rock mass have a significant effect on its mechanical properties and damage and fracture. The influence of fissure angles and bridge lengths on rock mechanical properties and failure was analyzed by uniaxial compression test and DIC technique. The research findings are as follows: The peak stress and elastic modulus of the samples have an obvious change trend with the change of the fissure angle. Compared with the length of the rock bridge, the fissure angle has a more significant effect on the mechanical properties of the rock. With the increase of fissure angle, the number of surface cracks, main failure cracks and surface spalling decreases, while the area of falling blocks increases obviously. However, with the increase of bridge length, the characteristics of crack propagation and spalling are basically the same. In the process of crack propagation, the connection of rock bridge is related to the fissure angle and the length of rock bridge. In the low fissure angle, the failure mode of rock samples is dominated by tensile failure cracks; With the increase of the fissure angle, the performance is as follows: the tension damage crack to shear damage crack transformation to form a mixed tensile shear damage mode; At the same time, with the increase of bridge length, the more difficult the rock bridge is to penetrate, and the local crack expansion failure changes from tensile-shear crack to tensile crack.

Coral sand is an important material for island and reef engineering construction. Its physical and mechanical properties in different marine environments directly affect the design, construction and long-term operation of island and reef structures. In order to study the shear mechanical properties of coral sand under the influence of temperature and salinity, the triaxial drainage shear tests of coral sand in the South China Sea were carried out at different temperatures and salinity by using the self-developed temperature controlled pile-soil interface triaxial tester. The results show that similar to ISO standard sand, the shear stress-strain curves of coral sand have peaks, presenting its characteristics of strain softening; The shear strength of coral sand is not significantly affected by temperature, but it is sensitive to salinity. Compared with fresh water environment, the peak shear strength of coral sand in salt water environment decreases by 2.5%-8.5%, and the lower of confining pressure, the greater of decrease range; Salinity has a deterioration effect on the cohesion of coral sand, and its reduction range is about 30%, but the effect on the internal friction angle of coral sand is not obvious.

Taking Shiping large irrigation area in Yunnan Province as an example, this paper studied the economic value of irrigation water and analyzed the influencing factors of crops in the irrigation area through the benefit sharing coefficient method and residual value method. It is found that the economic value of irrigation water for cash crops and fruits is higher than that for food crops. At the same time, it is recommended to use the benefit sharing coefficient method to calculate the benefits in irrigation district planning. The results of this study can guide similar irrigation district planning and help the construction of high standard modern irrigation districts.

The large pulses superimposed on the upper guide swing time-domain waveform measured by the eddy current displacement sensor of a generator-motor in a certain pumped storage station which affects the accuracy of the post-data processing. The data measured were analyzed in detail, and a three-dimensional finite element simulation model was established for calculation and verification. It is concluded that the fixed mode of the magnetic pole lead of the generator-motor on the upper end shaft is the main cause of large pulse. The temporary measures and completely improvement measures to ensure the accuracy of data were proposed, which are he pulse data elimination method and the sensor replacement method, respectively. It can provide the reference for the accurate measurement of the upper guide swing of a generator-motor with the same type of shaft-through mode.

The phenomenon of oil spilling and oil spilling in the lubricating oil system of the water guide bearing occurs frequently during the operation of the pumped-storage unit, which significantly affects the safety and stability of the unit and the operating environment of the power station. With the help of CFD numerical simulation technology and VOF multiphase flow simulation method, the dynamic characteristics of water guide bearing lubricating oil system in the multi-oil level working condition under the pumping mode of the pumped-storage unit were explored. The research results show that under the low oil level condition, the system flow cycle is formed faster, the flow state is stable and the oil level is low during the transition process, so the oil rejection phenomenon is milder, but too low oil level may lead to unfavorable control of oil temperature; Under the condition of high oil level, the phenomenon of oil spillage in the early stage of the flow mostly occurs near the side of the Pitot tube of the rotating oil basin, and it mostly occurs on the other side of the Pitot tube in the later stage of the flow. Compared with the traditional method of increasing the diameter of the Pitot tube, the method of optimizing the outer wall of the Pitot tube is more effective in suppressing the phenomenon of oil spillage. The results provide a theoretical basis for exploring the causes of the oil spill phenomenon in the water guide bearing lubricating oil system of the pumped-storage unit and the optimization of the oil slinger.

Malfunctions resulting from rub-impact between moving and stationary parts of bulb tubular unit will jeopardize the safety and stability of hydropower units. Aiming at the bulb tubular unit shaft rubbing system, a coupled bending-torsional rotor-runner system with faulty oil receiver under multi-vibration source and corresponding differential equation were established. The Floquet theory was applied to investigate the stability of periodic solution. The results reveal that when faulty oil receiver is taken into account, the system dynamic feature alters dramatically, which aggravates the possibility of system instability and alternates frequency transition between steady and non-steady state. This fault aggravates the unsteady vibration characteristics of different rotating parts, especially for the runner structure response trend, which needs to be paid enough attention. The results can provide useful references for safe operation and stability analysis of bulb tubular units.

In order to analyze the flow characteristics of the plane S-type axial extension tubular pump unit, the software CFX was used to conduct three-dimensional full channel numerical simulation, and the energy gradient theory was used to analyze the flow characteristics of pump unit under different working conditions. The results show that under different flow conditions, the water flow in the inlet passage of the plane S-type axial extension tubular pump is very smooth, and the overall difference is small. The flow pattern in the outlet channel is quite different, and the smaller the flow rate is, the worse the flow pattern in the outlet channel is. The pressure pulsation at the same position in the plane S-type axial extension tubular pump unit is the largest under low flow conditions. The difference of energy gradient in the outlet channel is the largest under the condition of small flow, which indicates that a large energy loss will occur in the outlet channel under this condition. When designing the outlet passage of the plane S-type axial extension tubular pump unit, the length of the smooth section of the outlet passage should be increased as much as possible to ensure the uniform distribution of energy gradient. The research results can provide theoretical guidance for better understanding of the plane S-type axial extension pump device and optimization design.