When the diffusion angle of each side of the wing wall in the gate is 12°, the horizontal distribution of outlet velocity of single-stage stilling basin is easy to be uneven in the medium and low water level period. To solve this problem, based on the physical model test, the law of horizontal distribution of outlet velocity of two-stage stilling basin was studied. The results show that with the decrease of downstream water level, the outlet velocity at the left and right banks of the second stage stilling basin changes in four stages: decrease- increase-decrease-increase, and the initial water level and water level range of each stage were closely related to the Fr. The smaller the incoming flow Fr is, the stronger the horizontal diffusion ability of hydraulic jump in the second stage stilling basin is, and it will be less disturbed by the backflow on both sides of the first stage stilling basin. The range of water level in the second stage will be larger, and it is more suitable for the medium and low water levels. The closer the downstream water level is to the end water level of the second stage, the greater the outlet velocity at both sides of the second stage stilling basin is, and the horizontal distribution of outlet velocity is more uniform. When the incoming flow Fr is the same, the regulating effect of the second stage stilling basin is more significant at low water level, and the energy dissipation rate is greater. The results can be used as a reference for the design of energy dissipation facilities under the gate and the operation management of the gate.

In view of the problem that the current 180° turning pool of the fishway has poor flow condition and affects the fish's upward tracing, the water flow condition was improved by extending the length of the upstream and downstream of the turning section and adding the staggered guide plate. Based on the study of a certain vertical slot fishway, numerical simulation was used to research on the distribution of flow regime, velocity, turbulent kinetic energy and turbulent dissipation rate of four turning pool structures. The results indicate that extending the length of the upstream and downstream of the turning section and adding the staggered guide plate can effectively guide the mainstream to center, maintain the stability of the mainstream and avoid the formation of a large-scale recirculation zone, and it is beneficial to migratory fish. The results of this study can provide reference for the reconstruction and design of fishway.

The vertical slit fishway has the capacity to better cope with the fluctuation of water level in both upper and lower sections and favorable water flow conditions. Three schemes were designed for the shape of the fishway tank chamber of a certain project fishway. The physical models verified with a 1∶5 scales were used to investigate the impact of the tank chamber's structure on the flow pattern, maximum flow velocity, and hydraulic properties of mainstream region under different size and type of baffle and guide plates. This was done through numerical simulation calculation. They performed a test of the physical model on the optimal shape with scale of 1∶5. The physical model of the overall with scale 1∶20 was used to analyze the maximum velocity along the water depth and the vertical slit, and the diversion flow of the fishway under different water depth conditions was proposed, providing reference and reference for similar projects.

The structure of fishway is the major factor that fish migrates successfully. The impact of pier head structure and horizontal interval of baffles on the hydraulic characteristics of a vertical slot fishway pool were researched. Twelve different working conditions were composed of two factors, namely, the diversion angle of pier head and the relative position of baffles. The RNG κ-ε turbulence model was used to simulate the hydraulic characteristics of fishway. The results indicate that the influence of pier head structure on hydraulic characteristics is mainly reflected on velocity and turbulent energy, and the smaller the diversion Angle, the smaller the velocity and turbulent energy are. The distance between flow deflector and baffler plate changed the mainstream flow pattern and area size, and then affected the distribution of flow velocity. When the relative position of b₀/L=0.15 or so, the flow pattern in the pool was reasonable, which met the basic requirements of fish migration.

To accurately evaluate the comprehensive utility tunnel under river shield tunnel construction safety, reduce the safety accidents in the construction process, based on the method of risk breakdown structure (RBS), risk evaluation index system of four first-level indicators was constructed including engineering geological risk and comprehensive utility tunnel itself risk, environment risk, construction risk management. Based on the linear combination of interval number analytic hierarchy process (AHP) and indicator correlation method (CRITIC), the comprehensive weight was determined. Based on matter element theory, the weighted average relation degree was calculated to determine the final evaluation result. This method was applied to the comprehensive pipe corridor project of Yueyang Avenue sewage treatment at the Wangjia River section. Monte Carlo method was used to analyze the sensitivity of 15 basic indexes based on matter-element theory. The research results show that the construction project of Yueyang Avenue sewage treatment comprehensive pipe corridor at Wangjia River section is medium-risk, which is consistent with the actual situation. The sensitivity analysis shows that the surrounding rock strength and the buried depth of tunnel are more sensitive. The research results can provide a basis for the safety control decision and measure making of the project.

Affected by the construction progress and other objective factors, the rock anchor beam may undergo loading with incomplete support, which seriously threatens the structural stability. In this paper, the rock anchored beam of a large hydropower station was taken as the research object. The three-dimensional nonlinear finite element simulation method was used to simulate the excavation of the main powerhouse and the filling of the rock anchored beam according to the actual excavation sequence. The continuous medium cementation element was introduced to simulate the weak contact between the beam concrete and the rock mass wall seat. The simulation results show that the load condition has a little impact on the stress and deformation of surrounding rocks, the initial support structure, and the rock anchor beam. The cementation surface between the surrounding rock and the rock anchor beam has a tendency to open, but it does not behavior obvious opening. The monitoring data such as the stress of the rock anchor beam and the deformation of the joint between the anchor beam and the rock wall remain basically unchanged, and no abnormal data are found, proving that the working state of the anchor beam is normal.

In view of the current problems such as less research on the combined support of anchor cable and frame lattice beam in slope reinforcement, the actual project of slope support on the left bank of a hydropower station was taken as the background. The stability of the original slope was analyzed by combining the limit equilibrium method and the finite element strength reduction method. The combined support scheme of anchor cables and frame lattice beams was studied. It mainly included anchor cable anchoring force calculation, anchor cable arrangement spacing, anchor cable length, optimal incidence anchoring angle and frame lattice beam size, etc. Finally, the support effect was studied by combining with numerical simulation. The results show that the original slope needs to be reinforced and supported. The error of the original slope safety coefficient obtained by the finite element strength reduction method is less than 1.5%-2.0% with the limit equilibrium method. The temperature loading method was used to simulate anchor cable prestressing for stability analysis of slope with combined support of anchor cable and frame lattice beams, and the combined support is effective and no obvious slip crack surface appears after the support. The study can provide reference for similar slope support projects.

In order to study the degradation of mica-quartz schist under the action of dry-wet cycles, which widely distributed in Shiyan, Hubei province was taken as the research object. The hydroscopicity test, wave velocity test and scanning electron microscope test were carried out on the samples under the action of dry-wet cycles, respectively, to reveal the law and mechanism of physical deterioration. The test results show that the water absorption increases greatly, the wave velocity decreases and gradually tends to be stable with the increase of the number of dry-wet cycles. Besides, the surface of the sample was gradually disseminated into reddish-brown, and the foliation was gradually cracked and connected. Finally, the flake particles became more, round and granulated, the number of cracks increased and the micro-fractures gradually expanded, so the water absorption rate increased and wave speed decreased of mica-quartz schist under the action of dry-wet cycles.

Since the mechanical properties of dam materials can directly affect the settlement deformation and structural stability of core wall DAMS, it is necessary to explore the mechanical properties of soil-rock mixture and the internal deformation and failure mechanism by means of macro and micro in order. Taking the Rumei Hydropower Station in Tibet in Lancang River as research background, particle flow code (PFC) method based on discrete element was used to carry out large-scale triaxial numerical simulation test. The results show that with irregular enhancement in the form of block stone, the stress peak nodes was in advance, peak strength increased obviously with significant softening characteristics, shear shrinkage was not obvious, and the dilatancy is prominent; The shear zone evolved from a single “工” shape to a complex “工” shape. The thickness increases from 45 mm to 105 mm, and the final swelling failure area increases exponentially to 35 000 mm². The extreme value and the number of force chain strength increased. Increasing the stone content was the key to improve the peak strength of the sample. When the rock content was low, the shear shrinkage characteristic was prominent, and the dilatancy characteristic was not obvious. With the increase of the stone content, the “gear” effect of the block stone was enhanced, and the shear zone failure mode was transitioned from smooth reverse “S” shape to multiple irregular shear zones, with the thickness increasing from 47.5 mm to 105 mm, the swelling failure area evolving from 12 800 to 35 000 mm², and the number of strong chains increased. The extreme strength of the force chain was increased from 10.49 kN to 164.30 kN. In conclusion, it is suggested to select blocks with high irregularity and increase the stone content to enhance the structural strength stability. The research can provide reference for the stability evaluation of the project in the later stage and the work of the proposed dam.

The study of the effect of water vapour on soil heat and moisture migration patterns at different heat source temperatures is of great significance for the application of soil heat storage and ground source heat pump technology. In this paper, a numerical model of one-dimensional unsaturated soil water-vapour-thermal coupling migration was constructed by Hydrus-1D software, and the numerical simulation study of sandy soils with and without water vapour migration at different heat source temperatures was carried out. The results show that for soil heat migration, taking into account water vapour migration increases the radius of influence of the heat source from 60 cm to 78 cm, an increase of 30%; For soil moisture migration, the radius of influence of the heat source increases from 78 cm to 100 cm, an increase of 28.21%. Compared with not considering water vapor migration, considering water vapor migration can reduce the temperature loss during soil heat storage, and the decrease of temperature loss increases with the increase of heat source temperature. When the temperature of the heat source is above 70 ℃, the temperature and moisture fields of the soil change unsteadily and dryness may occur in the vicinity of the heat source.