In order to evaluate the quality of "stepped" concrete cut-off wall of Hejiagou reservoir dam, the ground penetrating radar was used to detect the whole cut-off wall, and the cross-hole ultrasonic method was used to detect the " steps" of the concrete cut-off wall. The detection shows that the overall quality of the cut-off wall is good. Core drilling and water pressure test were carried out in the areas where there may be abnormalities, and the quality of the cut-off wall was comprehensively evaluated in combination with the monitoring data of the osmometer in front of and behind the cutoff wall. The results show that no major quality defects are found on the cutoff wall, local abnormalities exist, and the overall working performance is normal. This comprehensive geophysical detection method can effectively reflect the actual quality of the "stepped" cutoff wall, and the comprehensive utilization of relevant technologies can provide reference for similar projects.

Dewatering in deep well would lead to the decline of groundwater level and reduce the strength and stability of the soil, which affects the construction safety of the diversion tunnel. In order to study the influence of deep well dewatering on the seepage field of the tunnel during the construction period, a three-dimensional seepage finite element model of Chuanqin tunnel of Xixiayuan water control project and irrigation area project was established. The construction plan of the tunnel and the change of Qinhe water level were considered to analyze the seepage characteristics of the tunnel under the conditions of deep well dewatering and without dewatering. The results show that the dewatering of the deep wells affects the tunnel excavation, changes the potential distribution characteristics of the seepage field around the deep well, forms a falling funnel on the infiltration surface. The water level contour is in a backwater ring near the deep wells. Compared with the deep well without dewatering, the maximum seepage gradient and unit width seepage flow of deep well dewatering are increased by 18.6 times and 3.3 times, respectively, and the seepage stability of soil layer under all working conditions meets the requirements. The research results can provide a basis for the design and construction of similar water diversion projects.

The safe and economic support of pressure tunnel under the condition of high head and low crustal stress has always been a difficult design problem in water conservancy and hydropower projects. Based on the diversion and power generation pressure tunnel of Coca Codo Sinclair hydropower station in Ecuador, the combined support type of steel lining and reinforced concrete permeable lining was adopted within the framework of the Norwegian guidelines. The coupling theoretical model of steel lining and reinforced concrete permeable lining considering the influence of crustal stress was constructed to determine the starting point of steel lining. Based on the three-dimensional seepage field analysis, the optimal grouting depth and pressure of reinforced concrete permeable lining of high-pressure tunnel were determined. The analysis of monitoring data during operation shows that the selection of various indexes of the combined support of the pressure tunnel is appropriate. This study effectively solves the problem of safe and economic support of high head and low crustal stress tunnel, and ensures the safety and stability of pressure tunnel structure.

The local open channels play a certain role in regulating and storing water, but the water flow in the junction section with open channel variation and pressure is relatively complex, which may cause adverse water flow phenomena such as air intake, whirlpool and surges. In order to study the hydraulic pattern of the connecting section between the open channel and the pressurized tunnel, based on the water conveyance tunnel of Wenzhou Oujiang water diversion project, a 30:1 large scale normal local hydraulic model was built according to the gravity similarity criterion. The hydraulic pattern, water surface line distribution, velocity distribution and wave characteristics under different conditions were observed through hydraulic model tests. The flow trend, depth, velocity and wave characteristic parameters under different working conditions were obtained. The research results show that the flow in the open channel and the pressurized junction section through the gradual transition is in good shape, and there is no air intake, backflow and surge, which provides support for the safe operation of the project.

In order to analyze the dynamic response law of geotechnical slope, support and cavity structure under strong earthquake, taking a cavity section project in northwest China as an example, this paper firstly proposed a comprehensive management plan and then analyzed the management effect by combining field monitoring and FLAC^3D numerical simulation. Finally, the effect of support structure and cavern chamber on the dynamic response of rocky soil slope was analyzed under strong seismic load, and some suggestions for seismic protection of cavern section were discussed. The results show that after the treatment, the stability coefficient increases from 1.140 to 1.473, an increase of 29.2%; The imposition of the support structure effectively reduces the acceleration and displacement of the slope and cave roof axis; The presence of the cave chamber has a greater impact on the cave axis compared with the impact of the slope dynamic amplification effect; By analyzing the acceleration of the slope and the tunnel axis vault lining, the maddle is very important for the slope seismic resistance. It is suggested that the seismic protection length of the project should take the range of 3.4 and 4.8 times the diameter of the cave.

To analyze the impact of unsteady state friction and tube wall viscoelastic on leakage, based on the energy conservation theory of the transient flow in a closed pipeline, the leakage numerical model for the hydraulic transient pipeline was constructed considering the dynamic term in the unstable friction and the elastic viscosity effect of the pipe wall. The transient flow reverse analysis method (ITA) was improved. As a case study, Xujiaya Reservoir Irrigation District in Shandong Province was selected to carry out field experiments. The leakage process was assumed to be quasi-normal distribution. Based on the field water flow transient test data, pipeline leakage location and leakage amount were simulated. The simulated error was calculated by the ITA method. When a single point leakage occurs in the experimental pipeline, the average location error of the simulated leakage is 1.44%, and the maximum error is 6.89%, the average area error of the simulated leakage hole is 3.85%, and the maximum error is 14.77%. When multipoint leakage occurs in the experimental pipeline, the average error of the simulated leakage location is 1.31% and the maximum error is 3.91%; the average area error of the simulated leakage hole is 1.74% and the maximum error is 4.35%. The study results could provide theoretical and technical support for the leakage detection of water pipelines.

In order to study the hydraulic characteristics of staggered stepped energy dissipaters with different slopes, the flow pattern, flow field, pressure field and energy dissipation characteristics of staggered stepped and rectangular stepped energy dissipaters with slope of 1:2.0 and 1:2.5 under different flow rates were compared and studied by using the method of numerical simulation and model test. The results show that with the increase of the slope of the staggered step dissipator, the three-dimensional vortex scale formed at the step groove increases, the water flow is violent and the water depth is large. The absolute value of the vertical pressure of the step is larger, and the range of negative pressure zone increases. The horizontal pressure distribution of the step under the two slopes is similar, and the closer the step is, the smaller the pressure is. The energy dissipation rate of stepped energy dissipaters with a slope of 1:2.0 is larger. The energy dissipation rate of energy dissipaters with the same slope has a nonlinear relationship with the flow rate. The larger the flow rate is, the slower the energy dissipation rate changes. The staggered stepped energy dissipater is more fully aerated and has higher energy dissipation rate than the rectangular stepped spillway. The conclusions can provide a theoretical basis for the structural optimization of staggered stepped energy dissipater.

In order to obtain a more accurate calculation model of punching shear capacity of FRP reinforced two-way concrete slab, taking the FRP reinforced two-way concrete slab as the research object, using the research methods of literature review, data statistics, model analysis and regression calculation, and with the help of the commonly used calculation model of punching shear capacity of FRP reinforced two-way concrete slab, based on the collected punching test data of 98 FRP reinforced two-way concrete slabs, the inversion method of critical punching section coefficient of two-way slabs was used to establish a new calculation model of punching bearing capacity of FRP reinforced two-way concrete slabs. The model has high accuracy in predicting the punching bearing capacity of FRP reinforced concrete structures under concentrated load. The predicted results are in good agreement with the experimental database. The model has guiding significance for the design of punching shear capacity of FRP reinforced two-way concrete slab, which provides an important reference for further improving the accuracy of punching shear capacity calculation model of FRP reinforced two-way concrete slab in the future.

In order to study the influence of mineral admixture on steam-cured concrete under freeze-thaw environment, CT technology was used to scan the steam-cured concrete after freeze-thaw cycle, and the sectional images were obtained. The three-dimensional reconstruction of steam-cured concrete was carried out by Fiji and Avizo software, and the pore structure characteristics of the samples were obtained. The results show that the compressive strength of steam-cured concrete decreases with the increase of freeze-thaw times, and the deterioration of pore structure is the main reason for the decrease of compressive strength; The mechanical properties and pore structure characteristics of steam-cured concrete mixed with mineral powder and fly ash are better than those of ordinary steam-cured concrete under the same freeze-thaw conditions. The mineral powder and fly ash have a certain effect on improving the pore structure of steam-cured concrete.

To study the evolution law of member properties of hydraulic concrete materials under the coupling effect of freeze thaw cycles and salt erosion, early frozen specimens with different air-entraining agent admixtures (0, 0.005%, 0.01%) were selected and placed in a composite solution with a mass fraction of 3.5% sodium chloride +5% sodium sulfate for freeze-thaw cycle tests. Based on nuclear magnetic resonance (NMR)-fractal theory, the coupling relationship between the fractal dimension of the concrete pore volume and the damage degree of the specimens was constructed. The results show that the addition of air-entraining agents in concrete materials in appropriate amounts can effectively improve the mechanical properties such as elastic modulus and compressive strength of the members under the effect of salt freezing, and can improve the pore structure and frost resistance. The fractal dimension of concrete pore volume tested by nuclear magnetic resonance gradually decreases with the increase of freeze-thaw cycles, which indicates that the addition of air-entraining agent can change the internal pore structure of concrete in the initial state, and the effect is more obvious with the increase of air-entraining agent mixture. The correlation model between fractal dimension of pore volume and compressive strength was established by combining fractal theory, and the best functional relationship between fractal dimension D_MAX and compressive strength was found to be approximately exponential function. The regression coefficients R² is greater than 0.85, and the fitting effect is ideal, which provides a reference for durability assessment of concrete structures.