As for the open-pit slope with fault structure, studies on its deformation and failure characteristics were carried out by means of remote sensing images, field investigation and numerical simulation, and its safety factor was also calculated, so as to explore the influence of fault structure on slope stability. Then, based on the analysis of deformation and failure process of slope, the failure rule for open-pit slope with fault structure was discussed. It is found that the landslide hazard occurring on the north slope of the open-pit mine is attributed to an internal factor of fault structure combined with an external factor of unloading by underground mining. Under the combined action of disturbance by underground mining and cutting by F15 fault, a landslide is prone to occur along the fault structure, and then the failure zone will be gradually expanded. The deformation and displacement of upper slope above the F15 fault structure becomes relatively larger, and proceeds towards the eastern bottom along the F15 fault structure. The F15 fault structure changes the deformation and failure trend of the upper part of the northern slope. It is shown that when the safety factor of open-pit slope is 1.45, F15 fault zone is the potential sliding plane, and no larger deformation has occurred along the fault zone of the northern slope.

A slope of ionic rare earth mine was taken to study the variation of pore water pressure in the slope during and after rainfall events with different rainfall intensity, and the varied critical slip surface during these two periods of time was also studied by using the finite element Morge nstern-Price method. The results show that the rainfall intensity is a significant factor affecting the pore water pressure of shallow slope of ionic rare earth mine. The hysteresis property of rainwater infiltration into the slope is the internal reason for hidden risk of potential slope instability after rainfall events. The greater rainfall intensity will lead to faster formation of the 289 slip surface, higher peak value of greatly changed safety factor, as well as longer influence time. It is proposed for the first time that the development of ionic rare earth mine slope under rainfall conditions may experience four stages: safety, drastic internal variation, high landslide susceptibility, and relative safety.

In order to simply and effectively evaluate slope stability, four machine learning models based on chaotic particle swarm optimization (CPSO) were proposed to solve the existing problems of algorithm selection and hyper-parameter optimization in traditional machine learning model, and their prediction performance were comprehensively compared among each other. A database consisting of 221 open-pit slope stability cases was established, in which 80% of the data were used for training and 20% for model testing. Based on the comparison between the prediction results of four models and the verification results of engineering practices, it is found that the support vector machine (SVM) based on CPSO is superior than other three machine learning models in terms of prediction of slope stability, presenting an accuracy up to 88%. Thus, it can provide a reliable prediction for the safety of slope in open-pit mine.

The stability of slope with fault under the impact of  blast-induced seismic wave was analyzed by using simulation to study the dynamic response of slope with different fault thickness under the impact of explosive vibration. The results show that there exists elevation amplification effect when blast-induced seismic wave propagates along slope surface and fault area. The thicker the fault, the faster the attenuation of blast-induced seismic wave. As the fault becomes thicker, the displacement of slope under the action of blast-induced vibration gradually increases, and the overall deformation resistance becomes smaller. Under the action of blast vibration, the fault with different thickness obviously brings different influence to slope stability. With the fault thickness of 2-8 m, the slope stability decreases continuously and rapidly, and tends to be stable as the fault thickness exceeds 8 m.

The single application of analytical hierarchy process (AHP) and grey relational analysis (GRA) algorithm is always affected by some subjective factors, leading to great deviation between the obtained evaluation result and the actual result. In view of this problem, a composite algorithm based on an integrated range analysis with GRA and AHP was proposed. Then, a phosphate mine in the southwest China was taken as an example, and this algorithm was adopted  to analyze the sensitivity of factors, including gravity, internal friction angle, cohesive force, elastic modulus and Poisson'sratio, to the stability of slope in the Area A. The results show that the sensitivity of those influencing factors to the slope stability in Area A is in the following descending order: internal friction angle, cohesive force, gravity, elastic modulus, Poisson's ratio. It is found that the analysis result is consistent with the actual situation of the mine.

With a water cut-off and slope reinforcement project in Tenglong open-pit mine in Hebei Province as the background, a three-dimensional numerical model was established for finite slope with a retaining wall. Firstly, this numerical model was verified for its validity, and then was adopted in numerical simulation and analysis for the distribution law of earth pressure on the back of wall under translational motion. The results show that as the bench becomes wider, the angle of inclination for sliding surface of finite slope falls down to zero first, and then is gradually increased. When the bench is 9 m wide, the numerical solution of passive earth pressure on the back of wall is almost consistent with the analytical solution in term of its variation rule, which fully verifies the validity of this numerical model. The passive earth pressure presents nonlinear distribution, and the active earth pressure presents convex curve distribution. With both the stability of retaining wall and the construction cost taken into consideration, it is recommended that the slope degree should be set at 30° and the bench should be 9 m wide.

A shear creep test was performed for weak intercalation in order to investigate influence of creep characteristics of weak intercalation on slope stability. The obtained curve from the test was fitted according to Cvisc creep constitutive model, and the creep of slope with weak intercalation was calculated by using finite difference method to analyze the variation in long-term displacement and shear strain increment of the slope. The results show that the weak intercalation has typical creep characteristics. The results obtained from the numerical calculation with Cvisc model are basically consistent with the actual monitoring data. The creep characteristics of weak intercalation cause not only increase in the displacement, but also significant changes in the distribution form and orientation of the overall displacement of the slope, especially greater displacement at the top and in the middle of the slope. As a result, the slope body experiences an increment in the shear strain, which is then expanded and finally tends to stable.

The west slope of SCM copper cobalt mine in DRC was taken as an example for determining the shear strength parameters of rock mass by a laboratory triaxial compression test, back analysis of landslides, evaluation of rock mass quality and strength conversion with Hoek-Brown criterion, and then the obtained strength parameters were verified. The results show that due to the size effect of the samples, there may be deviation in the cohesion of rock mass shear strength obtained from the laboratory triaxial compression tests. It is found that with the obtained parameters used in slope stability analysis, more accurate evaluation results can be obtained from the slope model with higher sensitivity to friction angle, while lower accuracy from the slope model with higher sensitivity to cohesion. Under the same working condition, the parameters of slope rock mass obtained from the back analysis of shallow landslides can be used for analyzing local or single bench stability, and the parameters of slope rock mass from back analysis of deep-seated landslides or the landslides due to weak structural planes can be used for overall stability analysis. It is found that the shear strength parameters obtained based on Hoek-Brown failure criterion are close to the results from laboratory triaxial compression test, also easy to operate and more accurate, which can have a wide application.

It is difficult to simulate and analyze distribution of seepage field for the slope at the entrance of excavated tunnel during heavy rainfall. Aiming this problem, a slope project at a tunnel entrance was taken for study, and FISH language in the FLAC3D was redeveloped to determine the permeability coefficient of soil under different saturation state during rainfall infiltration, and the boundary conditions for rainfall infiltration were updated in real time. In addition, the pore water pressure, matrix suction distribution, as well as safety and stability of the slope at the tunnel entrance after different support schemes were all analyzed with different rainfall durations. The results showed that after 24 hours of heavy rainfall, the slope before and after a combined support including anti-slide piles and anchor cables all reached saturation state, that is, the saturation line ran through from the foot to the crest of the slope, while the slope, after benching and being supported with bolt, had its surface soil from the foot to the secondary platform of the slope under a saturated state. As for the slope at tunnel entrance supported by anti-slide pile combined with anchor cable, the variation law of its safety factor during rainfall was consistent with that of the slope without support treatment, showing that the factor of safety tended to be stable after an initial rapid decrease, and gradually reached 1.2. As for the slope after benching and being support with bolt, its factor of safety decreased a little and maintained above 1.8. It is concluded that the factor of safety, excavated earthwork quantity and total investment for the support scheme should be taken into consideration before starting a slope engineering at a tunnel entrance, and a combined support scheme including anti-slide pile and anchor cable is superior to the scheme including benching and support with bolt.

The landslide at level of 298~370 in Nanfen open-pit iron mine was taken as an example in the study. A geomechanical model constructed for it based on the similar theory was taken in an experiment and FLAC^3D numerical simulation. The variation characteristics of slope landslide and anchor cable at different excavation stages were investigated, and impact of different excavation methods on slope stability was also analyzed based on comparison. The experimental results of the geomechanical model show that the anchor cable deforms and bends during the excavation, and there is a significant difference in the displacement between the sliding body and the horizontal rock mass before the sliding body fails. The numerical simulation results show that after open-pit mining, the maximum displacement in the X direction is 17.06 cm, and the maximum subsidence in the Y direction is 10.31 cm. The anchor cable obviously restricts the vertical displacement of the sliding body, and stress concentration and displacement mutation can be found in the anchor cable. It is found that the numerical simulation results are consistent with the experimental results of the geomechanical model. In actual engineering, the sudden change of displacement can be taken as the basis for monitoring slope instability. Compared to the excavation without benching, a benched excavation can bring in smaller displacement and stress variations, thus leading to high slope stability.

In view of potential instability and landslide of waste rock dump in Fankou Lead-Zinc Mine due to the effect of rainfall, the slope stability of waste rock dump was analyzed using FLAC^3D numerical simulation based on the considerations of a 1-in-50-year rainfall event and no rainfall condition, as well as after the slope cutting treatment. The results show that rainfall will significantly increase the potential slope instability of waste rock dump. The maximum safe slope angles should be 37° and 43° respectively in consideration of rainfall or no rainfall conditions. After slope cutting, the factor of safety of the slope under rainfall conditions is 1.43, indicating the slope with high stability.

For studying the open-pit slope collapse in a metal mine caused by transition from open-pit to underground mining, a 3D numerical simulation method was used to analyze the progress of plastic zone in the surrounding rock of ore body, and the law of variation for the plastic zone distribution in the surrounding rock. ① Tensile failure is the main cause of failure in the strata above the goaf, while the other parts of strata are predominated by shear failure, and the plastic zone of the underground goaf extends to one side of the western slope of the open pit. ② The eastern ore body is mined by cut-and-fill, which controls the surface subsidence to some extent, and plastic zone occurs in the western slope and the bottom of open pit near the western slope. ③ At the early stage of mining of western ore body, there are more plastic zones occurring in the western slope and the bottom of open pit, and the subsequent mining of horizontal ore body has little impact on the plastic zone of the ground surface. ④ The progress of plastic zones can be divided into three stages with two abrupt change points: at the first stage, cracks start to occur on the western slope, and collapse and landslide occur in some parts; at the second stage, a large scale of collapse and landslide occur on the slope, and cracks occurs at the bottom of the open pit, and void collapse also occurs at the toe of the western slope; at the third stage, the proportion of plastic zones increases gradually. The research results can provide reference for safety in mine production.

To realize the slope deformation prediction for open-pit mines and overcome the shortcomings of low prediction accuracy of traditional algorithms, an IGWO-SVM model was established for the slope deformation of open-pit mine by adopting an improved gray wolf optimizer (IGWO) and support vector machine (SVM). The grey wolf optimizer was firstly improved by introducing non-linear decreasing convergence factor strategy and inertia weight strategy to determine the SVM parameters, so as to improve the accuracy of the model. Then, the observed slope deformation data of open-pit mine were input into the model for verification. The results show that compared with the SVM and BP models, the IGWO-SVM model has the absolute error maximally at 6.16 mm, minimally at 0.34 mm, and a mean relative error of 2.17%, indicating that the IGWO-SVM model can provide high prediction accuracy and has a good comprehensive performance. It is proven that this model is feasible to be used for the deformation prediction of open-pit mine slopes.