In order to explore the influence of water-binder ratio, fly ash, slag powder content and age on the compressive strength of full aeolian sand concrete, the compressive strength test of full aeolian sand concrete was carried out. The microscopic characterization of its physical composition was implemented in combination with XRD results. The compressive strength prediction model of full aeolian sand concrete was established by multiple linear regression. The results show that the compressive strength of full aeolian sand concrete increases first and then decreases with the increase of water-binder ratio. When the water-binder ratio is 0.4, the compressive strength is the largest. The growth effect of fly ash on compressive strength of aeolian sand concrete is not as significant as that of slag powder. The incorporation of fly ash and slag powder is easier to convert AFt into AFm. The established compressive strength prediction model has high accuracy and is suitable for sand concrete. The research results can provide theoretical basis and technical support for the engineering application of full aeolian sand concrete.

Based on the chloride ion diffusion model and aggregate gradation theory, the mesoscopic model of recycled concrete random polygonal aggregate was constructed using PYTHON and COMSOL. The validity of the model was verified by the existing experimental results. The calculation and analysis of the chloride ion erosion resistance of recycled concrete under different working conditions such as the diffusivity of new and old mortar, the thickness of old mortar and the replacement ratio of recycled aggregate was carried out. And then the diffusion law of chloride ion in recycled concrete and the influence law of critical factors on the chloride ion erosion resistance were studied. The results show that the simulation results are close to the experimental values, and the method can better simulate the diffusion of chloride ions in recycled concrete. The relationship curve between chloride concentration and depth shows discontinuous characteristics. With the increase of diffusion coefficient of new and old mortar, the chloride ion content increases gradually. The chloride ion erosion resistance of recycled concrete decreases with the increase of the thickness of old mortar and the replacement ratio of recycled aggregate.

To deal with the problems such as grouting pipe blocking and uneven diffusion of grout-enriched roller compacted concrete, the rheology, fluidity, stability, strength and time-varying properties of slurry containing micro-silica powder were studied. The entropy weight ideal point method was used to determine the optimal mix proportion by considering the working characteristics of the slurry and economic cost. The results show that adding micro-silica powder can reduce the bleeding rate and improve the compressive strength. When W/B=0.4, micro-silica powder reduces the yield stress and fluidity, and increases the plastic viscosity. When W/B =0.5-0.7, the yield stress and plastic viscosity increase with the addition of micro-silica powder. The rheology of slurry is related to the thickness of water film. With the increase of water-binder ratio, the effect of micro-silica powder on slurry’s performance gradually weakens. The yield stress increases linearly with time, and the plastic viscosity increases exponentially with time. Based on entropy weight ideal point method, the optimal mixture ratio of different schemes with fixed water-binder ratio can be obtained.

Conventional methods such as deformation monitoring, laser scanning and ground-based radar have certain limitations in the scene of high slope near the dam of hydropower station, so it is difficult to find the hidden dangers of high slope disasters near the dam in time and early-warning slope accidents. Taking a hydropower station in Jinsha River Basin as the research object, this paper proposes a high slope displacement detection method based on the UAV proximity photography, which mainly includes the UAV proximity photography data acquisition method for accurate path planning, generation of the SFM-MVS 3D model and point cloud model, and point cloud comparison algorithm based on adjacent 3D grid plane. Data acquisition, accuracy analysis and displacement comparison are carried out in the study area. The results show that the accuracy of this method in both horizontal and vertical directions reaches millimeter level, which can meet the needs of large-scale and high-precision displacement detection of high slope near the dam, and has strong scientific research and engineering practical value.

Fissure distribution has a significant effect on mechanical properties and damage failure of layered rock mass with complex fissures. Based on the uniaxial compression test and DIC technique, the influence of fissure location and fissure angle on the mechanical properties and failure of the composite fissure rock sample composed of sandstone-like and martial-like rocks was analyzed. The results show that the mechanical properties of composite fissure rock samples increase with the change of fissure location from sandstone, interface and marble and the increase of fissure angle. Influence of fissure location on rock sample failure: When the fissure is in marble, the initial crack is easy to be the far-field crack in sandstone, and the surface spalling occurs in both sandstone and marble, but the failure is more obvious in sandstone, is prone to "H-shaped failure". When the fissure is at the interface and sandstone, it is easy to produce wing crack and anti-wing crack at the crack tip of sandstone. Exfoliation occurs only in sandstone, "1γ shape failure" and "y shape failure" are easy to occur, respectively. At the same time, the stress-strain levels σ and ε corresponding to the initial crack generation at the same fissure angle increase with the change of fissure position from sandstone, sandstone to marble and marble. Influence of fissure angle on rock sample failure: When α=90°, the tip is not easy to crack, and when α=45°, the tip is easy to crack. When the fissure location is the same, the σ and ε of α=90° are the largest, while the σ and ε of α=0° and α=45°are the smallest. "H-shaped failure" occurs when α=0° and "y-shaped failure" occurs when α=90°. The research results are instructive for practical engineering construction and design.

In order to study the mechanical properties of rocks with prefabricated fissures, rock specimens with intermittent fissures at different angles were prepared. Uniaxial compression test was carried out on the specimens with fissures using uniaxial compression test equipment. It is found that the uniaxial compressive strength of 40° intermittent fissures is the largest, followed by that of 60°and 20°. The PFC2D was used to simulate the test process. The change law of microcrack and stress in the test process was analyzed. It is found that the strength of rock bridge has an important impact on the uniaxial compressive strength of the specimen. Through comparison, the change law of stress-strain curve of numerical simulation is basically consistent with that of physical test.

In order to study the seepage characteristics evolution of rock mass in the water level-fluctuating zone under condition of water-rock interaction, the dolomite in the reservoir area of Wudongde Hydropower Station was selected as the research object in this paper. The variation law of fracture seepage characteristics was obtained through the single fracture seepage test. With the help of SEM and 3D surface contour scanning technology, the variation law of fracture surface microstructure and surface morphological characteristics was studied, and the influence mechanism of fracture seepage characteristics evolution law was discussed. The results show that in the process of water-rock interaction, when the seepage pressure is constant, the seepage decreases exponentially with the increase of confining pressure; When the confining pressure is constant, the seepage increases linearly with the increase of seepage pressure; With the increase of water-rock interaction period, the seepage of fractures decreases rapidly at first and then slowly, and then increases slowly and tends to be stable. The water-rock interaction softens and dissolves the minerals at a certain depth of the fracture surface, and changes the micropore structure and surface morphological characteristics. Under action of confining pressure, the fracture surface is more closed. The further reduction of effective crack width is the main reason for the decrease of fracture seepage.

In order to solve the sliding failure problem caused by the wet expansion and dry shrinkage of expansive soil in the North Xinjiang water supply project, lime, cement and sand and gravel were used as the main curing materials. Through unconfined compressive strength test, direct shear test, compression test and SEM test, the influence of test dosage on the mechanical properties of improved expansive soil and the formation mechanism of microstructure strength under different improvement methods were studied by combining macro and micro. The test results show that with the continuous increase of the amount of lime and sand gravel, the soil strength increases steadily, while the peak value of cement improved soil appears when the amount of lime and sand gravel is about 7%. For lime and sand gravel, when the amount of lime and sand gravel is about 6% and 30% respectively, the overall compressibility of the improved soil is low, the cohesion is large, and the shear and compressive strength is high, which can meet the requirements of engineering application. The SEM analysis of lime and cement stabilized soil with the best mix ratio shows that a large number of curly flake hydrated gel materials are generated, which significantly reduces the pores compared with the original expansive soil, and the aggregates are closely cemented. From the macro mechanical properties, the mechanical properties and stability of the solidified soil are greatly improved.

It is of great significance to explore the variation law of soil thermal conductivity for fields of ground source heat pump systems and soil heat storage. The thermal conductivity variation law of loess and sandy soils with different dry densities and different saturations was investigated by TEMPOS thermal performance analyzer. The results show that saturation and dry density both have significant effects on the thermal conductivity of soil. The thermal conductivity of loess and sandy soil shows an overall increasing trend with the increase of saturation, but there is an obvious difference in the change pattern of thermal conductivity of loess and sandy soil. The thermal conductivity of loess and sandy soil increases with the increase of dry density, but the change range of loess soil is smaller than that of sandy soil. At the same time, 16 prediction models are evaluated based on the experimental data and the results show that the CCM model performs the best.

The determination of water conservancy project construction scheme is one of the most important decisions during the whole project construction period, which has an important impact on the progress and cost of the project. Considering the influence of main construction machinery and team configuration on construction period and cost, this paper established SVR model to simulate different construction schemes and corresponding construction period and cost data, and used multi-objective genetic algorithm to optimize construction schemes. Taking a box culvert project of South-to-North Water Transfer as an example, optimization model was established considering both construction period and cost. The optimization of project construction scheme was realized, and the applicability and accuracy of the model and method were verified.