To study the diversion risk of pumped storage power station construction under extreme rainfall, based on the idea of system risk analysis, the Copula-Monte Carlo method for diversion risk prediction was proposed by considering the correlation between upper and lower reservoir inflow. Joint distribution of the upper reservoir extreme rainfall and the lower reservoir flood volume was constructed to simulate the construction flood process caused by extreme rainfall. According to the characteristics of the upper and lower reservoirs diversion engineering, the risk model of the diversion system in the pumped storage power station was established to simulate the risk rate by considering hydrological and hydraulic uncertainty. Finally, a pumped storage power station under construction in southwest China was taken as an example, the results show Gumbel-Copula joint distribution fits the construction flood well in extreme rainfall cases, the diversion system risk rate is higher and more realistic when considering the correlation. It provides a reference for pumped storage power station construction diversion scheme selection and flood standard design under extreme rainfall.

The three-dimensional seepage analysis and control of underground plants and complex tunnels are related to the long-term seepage safety of underground spaces, which is one of the key technical issues facing the construction of pumped storage power stations by abandoned coal mines. Considering the reinforcement schemes for different surrounding rocks of the lower reservoir, the spatial location of the upper reservoir, the main powerhouse and the coal mine extraction area, a refined three-dimensional finite element model for seepage analysis of complex underground space in Longdong coal mine was established. Three-dimensional seepage field analysis was carried out for typical working conditions during the construction and operation periods. Important design parameters such as external water pressure and seepage volume of the underground tunnels during the construction and operation periods were obtained. Refined simulation of the numerous drainage holes in pumped storage power stations was implemented. By calculations of the seepage field under various unfavourable conditions, the optimal spacing of the drainage holes was determined. The research results are of great significance in the evaluation of seepage safety and the design of underground roadway protection schemes for the construction of pumped storage power stations by abandoned coal mines.

In order to study the shear resistance of the inclined section of steel fiber reinforced concrete beams with BFRP bars, this paper takes the steel fiber reinforced concrete beams with BFRP bars as the research object, and carries out the shear capacity tests of 9 steel fiber reinforced concrete beams with BFRP bars. The effects of failure mode, shear span ratio, BFRP reinforcement ratio, steel fiber volume fraction, and steel fiber range on the shear resistance of steel fiber reinforced concrete beams with BFRP bars are analyzed. The results show that the failure mode of steel fiber reinforced concrete beams reinforced with BFRP is mainly shear failure; The shear capacity of the inclined section decreases with the increase of shear span ratio, and increases with the increase of fiber content and BFRP reinforcement ratio; Setting steel fiber within the shear span of the support can better improve the shear resistance of the inclined section of the concrete beam with BFRP reinforcement. Finally, the formula for calculating the shear capacity of steel fiber reinforced concrete beams with BFRP bars is obtained by fitting test data, and the calculated results of the formula are consistent with the experimental results. The research enriches the design theory of inclined section of FRP reinforced concrete composite structure, and has reference value for the application of FRP reinforced steel fiber concrete composite structure in practical projects.

The shear performance of heterogeneous concrete is very important. In this paper, the parallel bonding model of particle discrete element was used to simulate the direct shear test process of concrete to reveal the shear characteristic and failure mechanism of concrete. The impacts of meso parameters, such as contact modulus, contact stiffness ratio, particle friction coefficient, tensile strength, ratio of cohesive strength to tensile strength, and contact friction angle, on the results of concrete direct shear test results were studied by controlling the variable parameters. The shear deformation resistance of specimen has a significant linear relationship with the contact elastic modulus. The contact stiffness ratio has little impact on the shear test results. Particle friction coefficient, contact tensile strength, ratio between cohesion strength and tensile strength, and contact friction angle have a significant effect on the shear strength parameters. Contact tensile strength, ratio between cohesion strength and tensile strength, and contact friction angle could affact the curve form after peak of shear stress vs. horizontal displacement. This paper provided a reference for particle discrete element simulation of direct shear test of concrete specimens.

In order to ensure the service performance of underwater concrete structures, it is urgent to carry out the detections and quantitative analyses of underwater concrete structure defects. Aiming at the common failure forms of underwater concrete structures such as collapse and indentation in practical projects, model plates with different shapes and sizes of indentations were designed and made. Using the side scan sonar carried by the unmanned ship, the defect model plates were scanned at a constant speed in a test pool. The acoustic characteristics of the defect areas were summarized by extracting the echo intensity waveforms of different shaped defects along the transverse sections. Image segmentation, mathematical morphology processing, and edge feature extraction were carried out on the original sonar image of different sizes of defects to obtain clear and complete contours of the defect areas. Through the interpretation of the longitudinal length of the defect areas, the quantitative analyses of underwater concrete defects were realized, and the identification error ratios were within 10%. It provides a new method for detecting the defects of underwater concrete structures.

In order to explore the microcrack initiation, propagation and damage evolution of rock samples with different crack types (opening and closed), inclination and crack length, based on PFC2D, the fractured rock sample model was constructed and the uniaxial compression numerical tests were carried out. The initial crack and failure characteristics of rock sample under different crack obliquity and type were explained from the perspective of mesoscopics. The damage analysis of rock samples was carried out from the perspective of energy. The results are as follows. With the increase of crack inclination angle, the peak strength of the open type is positively correlated, while that of the closed type decreases first and then increases. The elastic modulus is consistent with the change of peak strength. When 30°≤α≤60°, the microcrack initiation characteristics of the two kinds of fractured rock samples are consistent. When 60°≤α≤90°, the failure paths of the two rock samples are similar. The damage variable and correction coefficient were defined based on the energy of cementation failure, and the evolution model was established. The rationality of the model was verified from the perspectives of fracture type, inclination angle and length. The research results can provide a theoretical basis for further understanding the damage evolution process of fractured rock mass after loading.

Based on elasto-viscoplastic theory of Perzyna and strain energy theory and 3D yield criterion considering the effect of intermediate principal stress, a mesoscopic coupled elasto-viscoplastic-damage model is developed in order to explore the intermediate principal stress effect on the time-dependent behavior of deep hard rock in excavation damage zone. The model is implemented in a software for engineering rockmass fracturing process (CASRock). By comparing modeling results with experimental results, the model and the code are validated. Furthermore, the time-dependent behaviour of ^#1 laboratory of CJPL-II project is simulated, and the time-dependent fracture process of hard rock in excavation damage zones under different intermediate principal stresses are investigated. The results show that the time-dependent fracture behavior of hard rock exhibits an obvious interval effect of intermediate principal stress. It is found that the interval effect of the intermediate principal stress is affected by time through the isochronous curve clusters of the total viscoplastic strain and the intermediate principal stress. Finally, the existence of the excavation damage zone can promote the development of time-dependent fracture of its internal surrounding rock, thereby expanding the scope of the plastic zone.

Landslides induced by typhoon rainstorm has the characteristics of abruptness and difficulty in the investigation. Taking the Shanzao landslide that occurred during the typhoon "Lekima" as an example, based on 24 landscape data of Railway Sentinel-1 from Sept. 12, 2017, to Aug. 9, 2019, this paper analyzed the sequential cumulative deformation of landslides in this period by SBAS-InSAR technology and further analyzed the regularity of surface deformation of landslide mass with meteorological data. The results show that the deformation before the occurrence of Shanzao landslide is mainly divided into three stages: creep stage of landslide mass, deformation of front edge of landslide mass increases significantly and gradually expands toward the middle of the slope mass, and accelerated deformation stage of the rear edge of landslide mass. The vertical deformation rate and accumulated deformation data of InSAR monitoring points on the landslide mass show that the deformation rate and accumulated deformation in the front and middle of slope are small, and it mainly focus on the rear edge of the landslide, with the maximum deformation rate and accumulated settlement of 40 mm/a and 320 mm respectively. The landslide is a push-over landslide. The research results provide a new idea and method for the early identification, monitoring and early warning of landslides, and have a certain reference value for the prevention and control of landslide disasters.

In order to effectively grasp the reactivation mechanism and deformation law of the old landslide, this paper takes the bedding old landslide in a metamorphic rock area as the engineering background and combines the deformation monitoring results to carry out the existing deformation law analysis and deformation prediction research. The result of the case analysis shows that the deformation characteristics of the resurrection body of the old landslide are significant, especially the deformation in the middle of the resurrection body. Through the deformation prediction, it is concluded that the cumulative deformation of the resurrection body will still increase, and its stability will tend to weaken. Among them, the deformation in the middle position has no trend of convergence, that is, the increase rate will also tend to increase, and its stability will weaken more, so it is very important to carry out its prevention and control.

To accurately obtain the health performance level of a pumped storage unit (PSU), a health performance tendency prediction method based on convolution neural network-long short-term memory neural network (CNN-LSTM) is proposed. Firstly, a unit health state model based on Gaussian process regression was constructed to effectively characterize the operating characteristics of the PSU. Then, an index that can quantify the health performance of the PSU was proposed. Finally, by integrating the good local feature extraction ability of the CNN and the advantage of the LSTM in time series prediction, a prediction model based on CNN-LSTM was proposed. The experiments were conducted using monitoring data from a pumped storage station in China. The results show that the proposed method can betterly predict the future evolution of the PSU's health performance.