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In order to explore the influence of weak interlayer on blasting characteristics in natural rock mass, by using the particle flow code (PFC2D), a single hole blasting numerical model of hard rock with soft interlayer is established. The blasting experiments at different positions and thicknesses of weak interlayer are carried out. Then an in-depth analysis from the perspectives of crack effect, stress field and energy field is made. Results showed that: (i) When the explosion is initiated outside the weak interlayer, if the interlayer is located within about twice the radius of the crushing area, the closer the interlayer is to the blast hole, the higher the damage degree of the rock mass around the blast hole. And the number of cracks will increase by about 1–2% when the distance between the weak interlayer and the blast hole decreases by 0.5 m. (ii) When detonating outside the weak interlayer, if the interlayer is within about 4 times radius of the crushing area, the hard rock on both sides of the weak interlayer will in a high stress state. Under the same case, the peak kinetic energy and peak friction energy will increase by about 23 and 13%, respectively, and the peak strain energy will increase by about 218 kJ for every 0.1 m increase in the thickness of the weak interlayer.

With the development of hydraulic engineering, more hydropower stations are built in the complex geological condition. This work proposed a case study on stilling basin in complex fractured dam foundation using 3D nonlinear analysis. A detail implementation of the numerical mesh generation from profile to solid geometry using boundary representation (B-Rep) is illustrated. Considering the main factors like self-weight, hydrodynamic pressure, and uplift pressure, the stress and deformation results of stilling basin in complex fractured foundation are obtained. According to the calculation and analysis, the design stilling basin can meet the engineering requirements of hydraulic structure. However, it is suggested to carry out the necessary foundation treatment for the sericitized slate as well as fracture plane. The study will provide valuable reference in the analysis of related engineering.

The evolution of toppling deformation of anti-dip slope is essentially a process of energy dissipation and transformation. Aiming to study the characteristics of energy evolution in different stages, the DEM (discrete element method) software PFC (Particle Flow Code) was utilized to establish a two-dimensional numerical model for a bank slope in Chongqing based on geological background data and field investigation. The DEM model was proven to be reliable not only because the deformation discrepancy between the numerical model and actual bank slope was not large but also because some obvious fractures in the actual bank slope can readily be found in the numerical model as well. In this article, content about displacement in the shallow layer was analyzed briefly. Special effort was made to analyze the energy field and divide the toppling deformation process into three stages. (1) Shear deformation stage: this is an energy accumulating stage in which the strain energy, friction energy, and kinetic energy are all small and the deformation is mainly shear deformation in the slope toe. (2) Stage of main toppling fracture surface hole-through: all three kinds of energy present the increasing trend. The shear deformation in the slope toe expands further, and the toppling deformation also appears in the middle and rear parts of the bank slope. (3) Stage of secondary toppling and fracture surface development: strain energy and friction energy increase steadily but kinetic energy remains constant. Deformation consists mainly of secondary shearing and a fracture surface in the shallow layer. Secondary toppling and fracture surface develop densely.

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The existence of the interface between soft and hard rock often makes it difficult to control the blasting effect. Studying the influence of structural plane and delayed initiation time on rock blasting characteristics can make the blasting effect more controllable. In this paper, by using the Particle Flow Code (PFC2D) and particle expansion algorithm, the double-hole delayed blasting experiments of soft-hard rock are carried out, and the results are analyzed from the perspectives of fragment gradation, micro contact force and energy field. Results show that: 1) When blasting in hard rock, if the distance between structural plane and blasthole is about two times the radius of crushing area, it will easier to form large area fragments, and the fragments tend to be crushed with the increase of the distance. When the distance is 2–4 times the radius of crushing area, with the increase of delay time, the overall fragment area value increases first and then decreases, and reaches the maximum when the delay time is 4 ms. 2) When the structural plane existing in the rock mass, the delayed initiation will make the contact force become relatively uniform within a certain range. The main direction of contact force will appear in the uneven state of contact force generated by simultaneous or delayed initiation, which is close to the parallel or vertical direction of blasthole connection. 3) When blasting in hard rock, if the distance between the structural plane and the blasthole is greater than about two times the radius of the crushing area, compared with simultaneous blasting, the peak kinetic energy and peak strain energy of delayed blasting will be reduced by about 33% and 46% respectively.

Complex geological conditions often make the blasting effect difficult to control. In order to explore the influence of soft-hard rock strata on rock blasting characteristics, based on PFC2D software, combined with particle expansion loading algorithm, the numerical simulation blasting experiments are carried out. Firstly, the rationality of blasting method is verified by single-hole sandstone blasting experiment. Then, the soft-hard composite strata are established, and the single-hole blasting experiments of composite strata, with different distribution thickness of soft rock stratum and hard rock stratum, are carried out. The experimental results are analyzed from three perspectives: crack network state, internal stress of rock mass, and energy field. Results show that (i) the distance between the interface of soft-hard rock and the blasthole seriously affects the blasting effect. The law of crack number varying with the distance is obtained through further analysis. (ii) When detonated in the hard rock, if the structural plane is about 2 times the radius of crushing area from blasthole, the rock mass will be in a relatively high stress state due to the reflection and superposition of stress waves. (iii) When detonated in the hard rock, if the structural plane is about 2 times the radius of crushing area from blasthole, compared with pure hard rock case, the peak kinetic energy and peak friction energy are increased by about 15 times and 2.6 times, respectively, and the peak strain energy is attenuated by 18%.

In order to study the deformation characteristics of reverse slope, this paper took the slope of Xiaodongcao as the research object, applied the Louvain community detection algorithm, considered the influence of reservoir water level change, partitioned the slope deformation characteristics. The deformation characteristic zoning result was superimposed with the slope displacement cloud map and three types of geological geometric characteristic factor zoning map obtained by ArcGIS. The results show that：Community detection can quickly identify the closely connected part of slope network, and the specific location of this part is affected by reservoir water. After the community detection result is superimposed with the displacement cloud map, the areas with large deformation and close connection in the slope can be identified. It is found that the community with severe deformation have at least 5% more displacement and up to 21% more displacement than that with slow deformation. In addition, the location of leader nodes can be identified, and the number of leader nodes does not exceed 20% of the total nodes in the community, and its average displacement is at least 10% more than that of ordinary nodes, up to 36%. After the community detection result is superimposed with the zoning map of slope grade, it can be concluded that the slope grade within the community with severe deformation is greater than 60°, indicating that the larger slope grade is more sensitive to the bank slope deformation.