Dangerous Rock Mass Research Articles

Impact failure and disaster processes associated with rockfalls based on three‐dimensional discontinuous deformation analysis

AbstractRockfalls, a common geohazard in mountainous areas, have destructive impact capacity and may cause failure of dangerous rock masses in their runout range. For slope risk assessment, a thorough understanding of the impact failure processes and dynamic characteristics associated with rockfall movements is necessary. The aim of this study is to investigate the impact of rockfall failure behaviours and disaster processes on the dangerous rock mass along the way through three‐dimensional discontinuous deformation analysis (3D DDA). To validate the reliability and applicability of 3D DDA, numerous laboratory experiments are performed on the impact of downward moving blocks on the unstable block and block system (i.e. single block–single block, single block–block system and block column–block system models) by comparing the displacements, kinetic energies and movement states of blocks. Using the G318 national road in Tibet as an example, 3D DDA simulates the impact and disaster processes associated with upper rockfalls sourced from a complete giant block and multiple discrete blocks on lower dangerous rock mass. Further, rockfall failure modes, movement characteristics, block interactions and impact phenomena are investigated. Results show that 3D DDA can effectively simulate block movement and impact interaction. The upper rockfalls impact the initially stable lower dangerous rock mass, which is the triggering factor for failure of the lower dangerous rock mass. The blocks from the upper rockfalls interact and merge to move downward, increasing the total volume and impact capacity of the rockfalls. It has been discovered that the rockfall disaster caused by the impact of an upper rockfall comprising discrete blocks on a lower dangerous rock mass is more severe than that resulting from the impact of a complete block. Overall, the results of this research can be used to help predict and prevent rockfall disasters.

Analysis of fracture toughness deterioration and instability model of dangerous rock masses under freeze–thaw cycles

The instability of dangerous rock masses is primarily caused by the stress intensity factor at the primary structural plane exceeding the fracture toughness of the rock bridge section, which results in the propagation of fractures. Additionally, in cold regions, the fracture toughness of these rock masses gradually decreases due to freeze–thaw cycles. Initially, considering the deterioration of type I and type II fracture toughness in the rock bridge section and the frost heaving force between structural planes, an assessment model for the stability of dangerous rock mass under freeze–thaw cycles is established. Secondly, utilizing the theory of circular hole expansion, along with the Mohr-Coulomb yield criterion and maximum tensile stress criterion, a model is constructed to simulate the degradation of type I and type II fracture toughness in rock bridge segments under the influence of freeze–thaw cycles. The validity of this model was subsequently verified through experimental validation. Finally, through engineering case studies, the degradation pattern of the stability of dangerous rock formations under the action of freeze–thaw cycles was analyzed. The study reveals that the decreasing stability of dangerous rock mass under freeze–thaw conditions is intricately linked to the internal friction angle, elastic modulus, and initial tensile strength of the rocks. Notably, the long-term stability of hard and coarsely textured dangerous rock mass under such conditions generally improves. Conversely, the tensile strength of the rock bridge segment elevates, which is beneficial for the long-term stability of the rock mass. When the residual debris ratio exceeds 0.25, the instability of the rock mass deteriorates more modestly. To maintain long-term stability, managing debris loss or injecting fillers into the pores can be effective strategies.

Analysis of historical evolution characteristics and collapse process on July 18, 2023, of a dangerous rock mass at Guanyinyan in Baoxing County, Sichuan Province, China

Analysis of historical evolution characteristics and collapse process on July 18, 2023, of a dangerous rock mass at Guanyinyan in Baoxing County, Sichuan Province, China

Stability Deterioration Analysis of Toppling Dangerous Rock Mass under the Combined Effect of Vibration and Freeze-Thaw Cycles

To investigate the degree of stability deterioration in toppling dangerous rock mass under different action times, firstly, the vibration load generated by train travel in a single action and its decay law were studied, and the theoretical relational equation of rock strength deterioration under the action of vibration loading was obtained by analyzing the increase in half axle expansion of micro fissures inside the rock. Secondly, the freezing stress of the microfissures was determined according to the rock freezing and swelling theory, and the theoretical relational equation of rock strength deterioration under the action of freeze-thaw cycles was obtained by integrating the rock confinement and moisture migration conditions of the fissures wall. The stability coefficient of the toppling dangerous rock mass exhibited a rapid and then slow decreasing trend with increasing number of actions, which was non-linearly negatively correlated with the train running speed and the initial porosity of the rock, and non-linearly positively correlated with the freezing temperature. Controlling the freezing temperature and initial porosity of rock can significantly reduce the degree of deterioration in the stability of dangerous rock mass.

Study on the Dynamic Stability and Spectral Characteristics of a Toppling Dangerous Rock Mass under Seismic Excitation

To evaluate the dynamic stability of dangerous rock masses under seismic excitation more reasonably, a mass viscoelasticity model was adopted to simulate the two main controlling surfaces of a toppling dangerous rock mass. Based on the principles of structural dynamics, a dynamic response analysis model and motion equations were established for toppling dangerous rock masses. The Newmark-β method was utilized to establish a calculation method for the dynamic stability coefficient of a toppling dangerous rock mass. This method was applied to the WY2 dangerous rock mass developed in a steep cliff zone in Luoyi Village, and the dynamic stability coefficient time history was calculated. Subsequently, the acceleration response signals of the dangerous rock mass in different directions were analyzed using wavelet packet transform. The results show that the sum of the energy proportions of the first to third frequency bands in the n1 and s2 directions exceeded 95%. This suggests that the n1 and s2 directions of the WY2 dangerous rock mass suffered the initial damage under bidirectional seismic actions. Finally, the marginal spectra variations of the acceleration response signals in different directions were analyzed based on the HHT. The results show that the seismic energy in the n1 and s2 directions of the dangerous rock mass was found to be the most significant under seismic loading, indicating that the rock mass experienced the most severe damage along these two directions. This reveals that the failure mode of the dangerous rock mass is inclined toppling, consistent with the results of wavelet packet analysis.

Experimental Study of Single Structure Surface Dangerous Rock Mass Dynamic Characteristics Based on Constant Micromotion

The dynamic parameters of a dangerous rock mass reflect the degree of damage of the structure of its surface. There is still an urgent problem to identify the dynamic parameters of a dangerous rock mass based on the characteristics of the constant micromotion at its site. To address this problem, a method is proposed to identify the dynamic characteristics of a dangerous rock mass undergoing excitation caused by constant micromotion: (1) the vibration of a dangerous rock mass undergoing excitation from constant micromotion is classified as forced undamped structural vibration with a single degree of freedom. The ratio of the amplitude of the spectrum of the dangerous rock mass to the amplitude of the spectrum of the bedrock is defined as the relative amplitude spectrum. The first-order natural frequency is identified from the relative amplitude spectrum. (2) Bedrock is the source of excitation of a dangerous rock mass. When a mechanical wave propagates to a dangerous rock mass, it crosses the porous surface of media with structural damage, and mechanical wave scattering occurs. The frequency domain of the mechanical wave changes. The center frequency shifts to a low frequency. By means of laboratory model tests, the changes in the dynamic parameters of models of a cantilevered dangerous rock mass and a sliding dangerous rock mass with structural surface damage are analyzed. It is concluded that (1) based on the theory of vibration mechanics, the first-order natural frequencies of dangerous rock masses can be obtained from their relative amplitude spectra. The first-order natural frequencies of dangerous rock masses undergoing constant micromotion are measurable. (2) The damage of the structural surface of a dangerous rock mass with macroscopic fractures can be identified by its first-order natural frequency. The center frequency cannot reflect the development of fractures. The damage of the structure of the surface of a dangerous rock mass with microscopic fractures can be identified by the change in the center frequency in its high-frequency band. The first-order natural frequency cannot reflect the development of fractures. (3) There are limitations in using single vibration mechanics theory or elastic wave scattering theory to analyze the damage of the structure of the surface of a dangerous rock mass; it is more effective to integrate both methods.

Experimental Study on the Vibration Characteristics of Dangerous Rock Mass under Constant Micromotion

In mountainous areas, dangerous rock mass collapse is a serious threat to human life and property safety. However, how to effectively prevent and control the instability of dangerous rock mass is still an urgent unsolved problem. In this study, the dynamic characteristics of dangerous rock mass under constant micromotion were analysed from the perspective of elastic wave propagation. When the slip plane of the dangerous rock mass is damaged, many micropores and cracks will appear in the medium composed of the slip surface. With constant micromotion as the vibration source, the elastic wave propagates to the dangerous rock mass through the damaged slip plane. The high-frequency components of elastic waves scatter in pores and fissures, where energy dissipates. According to this characteristic, a laboratory simulation experiment was designed. In the experiment, the damage process of the slip plane was simulated by the freeze‒thaw process of frozen hydrosol. The experimental analysis showed that the centre frequency of the high-frequency part of the dangerous rock mass model and bedrock mass model decreased as the frozen surface continued to melt. As the dangerous rock mass model and the bedrock mass model continued to fit, the centre frequency of the high-frequency part of the two rock mass models rebounded. This phenomenon showed that the damage degree of the slip plane between the dangerous rock mass and the bed rock mass can be effectively reflected by the centre frequency of the high-frequency part of the two rock mass models. During the experiment, the dangerous rock mass did not slide in the whole process, indicating that the deformation index has difficulty reflecting the stability of the hidden dangerous rock mass. In addition, the application conditions of using the natural frequency characteristics of dangerous rock mass and the scattering characteristics of elastic wave in the damage identification of structural plane were analysed: (1) when the structural plane has macrofracture, the change of natural frequency of dangerous rock mass should be used to analyse the damage degree of structural plane; (2) when there is no macrofracture of the structural plane, the characteristics of elastic wave scattering should be used to analyse the damage degree of the structural plane. This study provided a new idea for the prevention and control of dangerous rock masses and is expected to provide a useful reference for the automation of dangerous rock mass prevention and control.

Research review and prospects of the 2000 giant Yigong long-runout landslide: Volume, formation mechanism and recurrence period, Tibetan plateau, China

The long-runout landslide is an unusual landslide with great drop height, long sliding distance, large volume, and high velocity, which is characterized by strong kinetic energy, fragmentation and entrainment effect. The landslide and its induced hazard chain may produce serious consequences. Based on remote sensing interpretation, field investigation and simulation, this paper summarizes the research progress of the 2000 giant Yigong long-runout landslide in Tibet, analyzes the initiating mechanism, volume and sliding velocity of the Yigong landslide, and further reveals that endogenic and exogenic geological processes are the main influencing factor of the Yigong landslide. It is also found that the landslide has a periodic initiating mechanism with characteristics of head-cut and recurrence. However, there are great differences in the existing studies on the volume of the slide source zone in the Yigong landslide. This paper calculates the landslide volume based on ArcGIS spatial analysis and obtains an initial landslide volume of approximately 9.225 × 107 m3. The landslide final deposition volume is approximately 2.81∼3.06 × 108 m3, which is consistent with the other researchers. Moreover, there are two potential dangerous rock mass in the slide source zone, with a total volume of approximately 1.86 × 108 m3. Dangerous rock mass may form the hazard chain of landslide-river blockage-dam break again and lead to significant disasters. Hence, we suggest the following research on Yigong landslide: Stability of the potential dangerous rock mass in the slide source zone, the prediction of the hazard chain, monitoring and early warning for the landslide. It is of great significance to guide the construction of major projects such as railway and hydropower projects and hazard prevention and mitigation in this area.

Methods and Systems for Modeling Porous Medium of Nanomaterials with Poor Geological Structure Based on ct Detection Technology

China is a country with frequent geological disasters. The geological disasters in different regions are different, such as earthquakes, landslides, collapses, karst collapses, and ground subsidence. With the development of science and technology and the improvement of engineering technology, the combination of image technology and digital technology is constantly developing. People can improve the accuracy of prediction by studying the characteristics of rock formation under different geological conditions while collecting geological data and sorting various information. And reliability, can more accurately identify poor geological conditions, can increase construction safety and reduce economic losses. Based on the comprehensive CT geological survey data, this paper uses nanomaterials to construct software DEM to model the porous medium of the Yanziyan dangerous rock mass in Jinfo Mountain, Nanchuan District, Chongqing and to estimate the area and volume of the collapse potential area of the high-steep dangerous rock mass parameter.

Evolution analysis of the Banbiyan dangerous rock mass in the three gorges reservoir area, China

ABSTRACT Due to the changing mechanical environment, it is difficult to determine the evolution process of the rocky bank. In this paper, the Banbiyan dangerous rock mass (BDRM) in the Three Gorges Reservoir area was taken as an example to analyze its failure characteristics. As for this specific evolutionary environment, a new judgment system was proposed, involving the comprehensive field survey method and indoor tests. The key information about the steep areas, interior areas, and underwater areas was obtained, which overcomes the limitations of the conventional survey methods. On this basis, combined with a simplified geo-mechanical model and dry-wet cycle tests, the evolution trend of BDRM under variable water levels was predicted. The results show that the stability of BDRM depends on many factors, including the self-weight of overlying rock mass (the location of the broken area), the strength of the broken area, the water pressure of the trailing edge crack (rainfall) and the reservoir water level. According to the calculation results, the BDRM is likely to slip along the broken area after 46 dry-wet cycles. The application of related methods can provide an important reference for judging the evolution trend of unstable rocky banks worldwide.

Study on Monitoring Methods of Stone Cultural Relics - Taking Shaoxing Yangshan Statue as an Example

In recent years, due to the structural factors of the rock mass itself, many rock masses are in an unstable state, and there are many structural fissures in the rock mass.There is a serious seepage phenomenon inside the cave, and the weathering diseases on the surface of the rock mass have appeared to varying degrees. Its cultural, artistic and scientific values need to be continued. Through modern instrument and scientific testing scheme, the horizontal displacement, crack and stress of reinforced anchor cable of dangerous rock mass are monitored in real time. After material reinforcement and repair, continuous monitoring is carried out to check the repair effect and ensure that the repair scheme is effective. Keywords : unstability; crack; weathering; monitoring DOI: 10.7176/CER/14-2-04 Publication date: April 30 th 2022

Stability Assessment of Dangerous Rock Mass of an Overhanging Slope in Puerdu Town, Southwestern China

Dangerous rock mass in the overhanging slope of Puerdu town has good free-face condition, high position, and great potential energy, identification and stability evaluation of which is a difficult problem in the disaster prevention. In this paper, the limit equilibrium method was used to evaluate the dangerous rock mass stability in the overhanging slope. Firstly, geomorphic characteristics and the distribution of dangerous rock mass are determined by the field geological survey. Secondly, six dangerous rock masses which may cause more threat are studied, with defining their failure modes and characteristic parameters. Finally, a simplified geological model is established, the stability coefficient of dangerous rock mass under different conditions is calculated by the limit equilibrium method, at the same time, stability analysis of dangerous rock mass is carried out based on the stereographic projection, and the hazard probability is estimated by the empirical formula. Results show that joints obviously developed in the dangerous rock mass of W1, W2, W3, W4, W5, and W6, with falling-type and toppling-type failure modes. In the natural condition, the dangerous rock mass is understable and unstable under the rainstorm and earthquake conditions. Consequently, rainstorm and earthquake are the key triggering factors of the instability and collapse of dangerous rock mass.

Trajectory Analysis and Risk Evaluation of Dangerous Rock Mass Instability of an Overhang Slope, Southwest of China

Analysis of the movement trajectory and risk assessment of the high-slope dangerous rock mass collapse are of great significance for preventing and controlling the geological disasters of collapse. This study firstly takes the dangerous rock mass of the high slope in Pu’erdu Town, Yanjin County, Zhaotong City, Yunnan Province, as the research object, calculates and analyzes the trajectory of collapse movement of several groups of dangerous rock mass with great threat, and RocFall are used to carry out numerical simulation analysis and verification. Secondly, the risk and vulnerability of the dangerous rock mass in the study area are analyzed, and the risk evaluation is carried out through the risk evaluation matrix to clearly define the risk level. Results show that if the dangerous rock mass collapses, the horizontal movement distance was approximately 53–88 m, and the maximum bounce height of the platform was approximately 3–18 m, which will seriously threaten the life and property safety of residents. There is little difference between the simulation of the collapse of dangerous rock mass by RocFall software and the calculation result of the formula. Although RocFall software is more intuitive and can be directly compared with charts, software cannot completely simulate the actual situation, and it is only suggested as a reference from design rather than a basis of design. The result of risk evaluation shows that there are 2 high-risk dangerous rocks, 3 medium-risk dangerous rocks, and 1 low-risk dangerous rock in this area. It is suggested that a reasonable and scientific engineering treatment scheme should be put forward as soon as possible in combination with the collapse trajectory of the collapsing movement.

Calculation of stability reliability of soft base controlled unstable rock and parameter sensitivity analysis

There are a large number of unstable rocks whose stability are controlled by soft base layer in the mountainous areas of southwest China, and they have caused serious harm to people’s lives and local economic development. Therefore, it is of great practical significance to study the stability and failure mechanism of such unstable rock. Taking the in Wulong District, Chongqing as an example, this paper analyzes the failure probability and reliability index of the unstable rock under different conditions by use of Monte Carlo method and on this basis, the sensitivity of the stability of dangerous rock mass to the main influencing factors is analyzed. The results show that the stability coefficient, failure probability and reliability index of are equal to 1.151, 26.245% and 0.642 under natural condition. However, the stability coefficient of decreases rapidly and the reliability index and failure probability increase obviously when combined with other factors such as rainfall or earthquake. The sensitivities of the influencing factors of the unstable rock are from top to bottom internal friction angle of soft layer, the horizontal seismic force, the cohesion of soft layer, the water content in the crack and the weight of soft layer. The research results can provide some reference for the stability analysis and engineering prevention of such unstable rocks.

Preliminary Identification of Geological Hazards from Songpinggou to Feihong in Mao County along the Minjiang River Using SBAS-InSAR Technique Integrated Multiple Spatial Analysis Methods

Landslides and collapses are common geological hazards in mountainous areas, posing significant threats to the lives and property of residents. Therefore, early identification of disasters is of great significance for disaster prevention. In this study, we used Small Baseline Subset Interferometric Synthetic Aperture Radar (SBAS-InSAR) technology to process C-band Sentinel-1A images to monitor the surface deformation from Songpinggou to Feihong in Maoxian County, Sichuan Province. Visibility analysis was used to remove the influence of geometric distortion on the SAR images and retain deformation information in the visible area. Hot spot and kernel density analyses were performed on the deformation data, and 18 deformation clusters were obtained. Velocity and slope data were integrated, and 26 disaster areas were interpreted from the 18 deformation clusters, including 20 potential landslides and 6 potential collapses. A detailed field investigation indicated that potential landslides No. 6 and No. 8 had developed cracks and were severely damaged, with a high probability of occurrence. Potential collapse No. 22 had developed fissures, exposing a dangerous rock mass and posing significant threats to the lives and property of residents. This study shows that the proposed method that combines visibility analysis, InSAR deformation rates, and spatial analysis can quickly and accurately identify potential geological disasters and provide guidance for local disaster prevention and mitigation.

Study on Dynamic Evaluation Method of Stability of Slope Controlled by Structural Plane Based on Deformation Characteristics

The study on deformation characteristics of structural plane is the research foundation of structural plane mechanics and hydraulics. In this paper, a calculation method for dynamic evaluation of the stability of slope controlled by structural plane based on deformation characteristics was proposed on the basis of shear reinforcement three-fold line constitutive model, and it was applied to the example of Raytheon landslide in Chongqing-Guizhou high-speed railway. By comparison, the calculated results were in good agreement with the measured displacement results, and the displacement development process of the dangerous rock mass can be well simulated, thus verifying the feasibility and engineering practicality of the method.

Channelized and unchannelized collapses of granular columns on a horizontal surface

Columnar dangerous rock mass is widely developed in many high and steep mountain areas around the world. It often collapses, disintegrates and produces debris flow, which is disastrous. The collapse process of the columnar dangerous rock mass is very similar to the collapse of granular column. In this paper, we report the results of an experimental investigation of the flow induced by the collapse of a column of granular material over a horizontal surface. Two different setups are used, namely, a channelized granular column collapse (i.e., two-dimensional) and an unchannelized granular column collapse (i.e., three-dimensional), allowing us to compare channelized and unchannelized collapses flows. The experimental data suggest that our experimental findings were markedly different from those reported by previous authors (i.e., include the channelized and unchannelized collapse flows showed differences in energy conversion and dissipation). In channelized collapse flows, the maximum vertical speed appears in the free fall regime, while, the maximum speed in the vertical direction of unchannelized collapse flows appears in the spreading regime. During the whole collapse process, i.e., in channelized and unchannelized collapse flows, the conversion of potential energy and kinetic energy does not occur uniformly, and the maximum kinetic energy of the channelized collapse flows is higher than that of the unchannelized collapse flows, and compared with the unchannelized collapse flows, the dissipation energy in the channelized collapse flows is lower. A series of experiments was performed to predict the behaviour of different granular columns (characterized by different initial aspect ratio (a), varying from 1 to 4). The data obtained from 2D experimental model and 3D experimental model have certain amount of difference, such as the particle runout distance (d1), the maximum central height (h2), and the deposition angle (i.e., β1, β2). These differences show that the 2D experimental model does not fully represent the 3D conditions (i.e., the role of side-walls on the channelized collapse flows characteristic is non-negligible). Accordingly, care must be taken when validating 3D models with 2D experimental data. The movement of the tower dangerous rock masses with collapse failure mode could be evaluated using this channelized and unchannelized granular column experimental results.

Calculation Method of Bonding Section of Joint Surface of Dangerous Rock Mass Based on Amplitude Ratio

In this study, through an analysis of vibration response characteristics of joint surface stiffness on dangerous rock mass, the relationship formula between amplitude ratio of the dangerous rock mass to the bedrock and the length of the bonding section of the joint surface is determined. The stability of the rock mass can be evaluated by combining the formula with the existing rock-mass limit equilibrium theory. This study proposes the existence of a resonance bonding length for the dangerous rock mass. When the length of the bonding section reaches the resonance bonding length, the dangerous rock mass has the largest response to the bedrock vibration. The study found that when the length of the bonding section of the dangerous rock mass is longer than the resonance bonding length, the amplitude ratio increases with the decrease of the bonding section and increases with the increase of the vibration frequency of the bedrock. When the length of the bonding section of the dangerous rock body is shorter than the resonance bonding length, the amplitude ratio decreases with the decrease of the bonding section and decreases with the increase of the vibration frequency of the bedrock. Indoor experiments were conducted by collecting the vibration time-history curves of rock blocks and stone piers and performing analysis and calculation, which proved the accuracy of the analytical results. Through the amplitude ratio of the dangerous rock mass and the bedrock, the bonding length can be calculated. This method can improve the calculation accuracy of the stability coefficient K of the dangerous rock mass.

Deformation Failure Mechanism and Motion Laws of Near-horizontal Thick-layer with Thin-layer Columnar Dangerous Rock Mass in the Chishui Red Bed Area

The collapse of dangerous rock masses, either due to natural causes (such as weathering by rain) or anthropogenic factors (such as engineering construction in the rock area), poses a threat to both life and property. Therefore, investigating deformation failure mechanisms and determining the movement characteristics of the rock masses after collapse can provide practical guidance for conducting linear projects while taking adequate measures to prevent the collapse. In this study, a dangerous rock mass on the right side of the Yuanhou Toll Station of the Rongzun Expressway was used to study the deformation and failure mechanism of near-horizontal and thick layer with thin-layer columnar dangerous rock masses in the Chishui red bed area. A high-definition 3D-surface model was generated by using unmanned aerial vehicle (UAV) tilt photography technology to obtain an aerial image of dangerous rock masses with spatial coordinates in the research area. The three-point method was used to interpret the structural surface of the dangerous rock mass based on the 3D model. A model for the deformation and failure of dangerous rock masses was developed via an engineering geological analysis. We simulated and analyzed the cause of deformation and failure of dangerous rock masses using FLAC3D software. In addition, the motions of rock fall were studied by performing simulations using Rockfall software. From the interpretation of the 3D model of the UAV, the dangerous rock mass developed two sets of dominant structural planes that were nearly vertical and perpendicular to the stratum level, cutting the rock mass into cuboids. Based on the analysis of a stereographic projection, the dangerous rock mass was in an unstable state. The results showed that the dangerous rock mass had a high stress concentration in the middle and lower soft rock, which is likely due to dumping collapse under self-weight and differential weathering. Moreover, rock fall has a 60% probability of causing damage to the road below the rock mass if it collapses, threatening the safety of passing vehicles and people’s lives and property.

Investigation and motion characteristics analysis of dangerous rock in high and steep slope based on UAV

The geological conditions in Southwest China are complex, and the dangerous rock hazards developed in the high and steep slopes has extremely high harmfulness and concealment. The traditional contact survey method is difficult to find out the geological hazard effectively under the limitation of complex and changeable terrain conditions. Unmanned aerial vehicle photogrammetric system has high flexibility and can obtain high-efficient, high precision and high resolution remote sensing images of geological disaster investigation area. By using the UAV photogrammetry system, the dangerous rock mass of the intake slope of Jinping secondary hydropower station is investigated. The working principle of UAV, the acquisition of high-definition image data and the construction of 3D model are discussed, and the feasibility of using the model data obtained by the system to investigate dangerous rock mass is demonstrated. Through repeated analysis and interpretation of the 3D real-scene model, the distribution characteristics of the dangerous rock hazard points of the intake slope are found out. On this basis, four sections are selected to simulate the movement track of unstable dangerous rock mass with Rocfall software, and the movement velocity, jump height and impact energy of different characteristic points of falling rock are calculated quantitatively with the formula.The research results provide an important reference value for the investigation of dangerous rock mass of high and steep slope in southwest China.