Pit Slope Stability Research Articles

Hydrogeochemical evolution and isotopic characteristics of groundwater-surface water interaction processes within the Kawere catchment and its hydrogeotechnical implication on pit slope stability at the Nsuta mine, Ghana

In geo-hazard prone heterogenous mining terrain with multiple geological structures, surface water may interact with its underlying groundwater system conveying large quantities of water to deeper aquifers, which could undoubtedly lead to pit-inflows and slope stability challenges for any close-by mining operation. A total of forty-three (43) water samples were collected from the atmosphere, surface, subsurface and the pit-water during dry and wet seasons, respectively to identify pit-inflow origin using hydrogeochemical evolution paths and end member mixing analysis of the major ions at the only manganese mine in Nsuta, Ghana. The major ions order was Na2+>Ca2+>Mg2+>K+ for cations and anions' order was HCO3− > SO42− > Cl−. The identified hydrogeochemical facies and proportions are Ca–HCO3- (68.75%), Ca–Cl2 (18.75%) and mixed Ca–Mg–Cl (12.5%) in the dry season and mixed Ca–Na–HCO3 (54%) followed by Ca–HCO3 (46%) in the wet season. Na+ is the preeminent cation whilst HCO3− is the preeminent anion. Saturation Index (SI) of carbonate and evaporate minerals, particularly calcite, identified groundwater-surface water (GW-SW) exchange flux pathways in the study area, and thus establishing geochemical modeling as a robust tool for identifying GW-SW exchange flux pathways in riverine and aquifer systems. The isotopic composition of the various water samples is depleted having strong mixing relationship of R2 = 0.96%, suggesting the waters have same origin with low d-excess indicating rainfall under lower humidity. End member mixing analysis suggested GW-SW interaction with the surface water contributing an average of 87% to groundwater in the mine pit during the dry season. The generally low hydrogeochemical and isotopic evidence of the various water sources indicate homogeneity pointing to the existence of GW-SW interaction. The fast-movement of the exchange flux has widened flow path leading to pit slope stability issues and huge pit-inflows. Therefore, the mine managers, stakeholders, and decision makers are strongly advised to promptly integrate hydrogeotechnical assessments into their operations as a sustainable remedial measure. This will enable them to continuously reduce the potentiometric head of the groundwater system and ensure cost-efficient mining activities. It is essential to take these actions due to the mine's location within two river stream catchments.

Evaluation of buoyant action of groundwater and surface water interaction on pit slope stability using hydrogeological-stratigraphic-structural assessment within the Kawere catchment of the Nsuta mine

ABSTRACT In open-pit mining operations where activities are conducted below water table or close to surface water bodies, the mine is potentially faced with dewatering and slope stability challenges. Appropriate evaluation of slope stability to obtain adequate slope safety factor has continuously been the centre of geotechnical research locally and internationally. This paper evaluates the influence of buoyant action propagated by groundwater and surface (GW-SW) interaction on pit slope designed in multi-layered fractured rock with complex hydrology using Hydrogeological-Stratigraphic-Structural Assessment (HSSA) at the Nsuta Manganese Mine in Ghana. LEM analyses of the Pit C-western slope estimated an overall factor of safety (FOS) of 1.1, probabilities of failure (POF) of 7.5% and the reliability index (RI) of 1.4 in the slope stress field. However, when the groundwater was introduced, the slope FOS was reduced to 0.13, POF of 100.0% and (RI) of 0.00 indicating failure. FEM numerical model points to the location of maximum shear strain and total displacement in the argillite zone within the rock mass. The FEM seepage analysis model estimated groundwater pore pressure data along the critical slide surfaces from the crest of the slope to the bottom of the rock slope ranging between 250 kPa and 4250 kPa with an average pore pressure of 2250 kPa within the pit slope. This proposed HSSA approach used in the study provides innovative insights into the percentage failure contribution of the individual lithologies to the overall combined lithological susceptibility of the slope under stress and groundwater failure mechanisms, pointing out Ru ratio in pit slope stability estimation as inadequate.

Stability analysis of pit slopes in Zapadno-Ozerny quarry to ensure mine safety

The article discusses the design parameters of open pit slopes and the approach to calculating the stability of open pit slopes. The main deformations of slopes of open pits are considered. An assessment of the influence of the stress-strain state of quarry slopes on their stability is made. On the example of an open pit at the Zapadno-Ozernoye field, the assessment of stability under the actual stress-strain state of the site was performed. Recommendations to determine the new boundaries of the open pit, in which the section of the South Eastern slope of the open pit will be stable are given.

Integrated D-InSAR and Ground-based Radar for Open Pit Slope Stability Monitoring and Implications for Rock Mass Young’s Modulus Reduction

Excavation and material stockpiling activities in the mining process cause a change in the distribution of forces and stresses in the material. As a result, the material will seek a new equilibrium by releasing the load through a landslide. As part of mitigation, it is necessary to monitor displacements occurring on slopes using high-accuracy devices. Ground-based radar is a technique considered to have good ability to detect displacements in real-time. However, ground-based radar has a weakness in that it cannot detect vertical displacement. One of the emerging technologies that is used for monitoring vertical displacements as LoS displacements is D-InSAR analysis. With the integration of both methods, displacements that occur horizontally and vertically on a slope can be detected properly. In addition, the decrease in rock mass strength due to displacement can be predicted based on numerical analysis using the finite element method. Monitoring was carried out from December 10th, 2021 to April 9th, 2022. The monitoring results from the beginning to the end of the period showed that the horizontal and vertical displacements that occurred in the low wall area were 1247.34 mm and 292.5 mm, respectively. Correlated with these conditions, the Young’s modulus value of the rock mass decreased between 3% and 35%.

Global analysis approach of stability of deep foundation pit slopes reinforced by underground diaphragm walls and prestressed anchor cables

The stability evaluation of deep foundation pit slopes is crucial, including the solution of the factor of safety and the location of the critical slip surface. Prestressed anchor cables and underground diaphragm walls are commonly used to reinforce pit slopes. By means of the dimensional increase technique and the global analysis approach of slope stability, a nonlinear optimization problem is defined for the stability analysis of pit slopes. In the optimization problem, the ordinates of discrete points on the slip surface and the factor of safety are both the decision variables, the objective function is the factor of security, and the constraints are the equilibrium equations and the convexity of the slip surface. Because the objective function is linear and the constraint functions are polynomials of degree three at most, the optimization problem is a classical optimization one that conventional optimization techniques can solve without recourse to modern optimization techniques such as the AI technique. Examples suggest that the proposed procedure is far more efficient and stable than the optimization models based on the methods of slides. At last, applications are demonstrated to ongoing deep foundation pit slopes situated at Tong Zhou – Beijing sub-center.

Open Pit Slope Stability Analysis in Soft Rock Formations at Thar Coalfield Pakistan

Open Pit Slope Stability Analysis in Soft Rock Formations at Thar Coalfield Pakistan

In-Pit Disposal of Mine Tailings for a Sustainable Mine Closure: A Responsible Alternative to Develop Long-Term Green Mining Solutions

In the next decades many of the old tailings storage facilities (TSFs) could be re-processed if one considers the prices of metals, new uses of metals which today are not valuable, and the application of new, more efficient metallurgical technologies. In this context, in-pit disposal of mine tailings (IPDMT) is an attractive alternative to be used as part of responsible mine closure: mines could reprocess the mine tailings and place them in an open pit as part of sustainable mine closure. This article explores a little-explored tailings disposal technique that has the potential to be considered as an environmentally friendly solution, returning mine tailings to their place of origin and providing long-term stability under a climate change scenario. This article presents the main features, benefits, and potential drawbacks of IPDMT, with an emphasis on: (i) a description of the main advantages and disadvantages of application; and design issues related to (ii) IPDMT physical stability (pit slope stability, tailings transport, placement systems); (iii) IPDMT hydrological stability (water management, seepage control, hydrogeological monitoring,); and (iv) IPDMT geochemical stability (geochemical characterization, acid rock drainage control, covers). The novelty of this article is the proposal to change the status quo of traditional management of mine tailings to a new paradigm where the technique of in-pit disposal of mine tailings can be considered a green mining solution for mine closure. Finally, some successful cases around the world that involved the implementation of this technique are presented.

Mine Slope Stability Based on Fusion Technology of InSAR Monitoring and Numerical Simulation

In this paper, the slope of the open pit of Dahongshan iron ore mine in Yunnan is taken as the research object, the safety coefficient and settlement values of the slope under natural and rainfall conditions are derived by the finite element software Midas/GTS, and the surface settlement versus time is produced by fusing the InSAR monitoring results of the study area for a whole year to judge the stability of the open pit slope. The results show that the settlement and deformation areas shown by numerical simulation and InSAR monitoring results are consistent; the comparison between InSAR monitoring results and rainfall intensity shows that the cumulative value of slope settlement has a high correlation with heavy rainfall. The safety coefficients of the slopes of the open pit under natural conditions and rainfall conditions are 1.50 and 1.21, the cumulative value of settlement in InSAR monitoring data for one year is 18.4 mm, and no obvious large deformation area is found. The use of numerical simulation combined with InSAR monitoring can realize the analysis of the stability of the slope of the open pit mine.

Comparing Shear Strength Dispersion Characteristics of the Triaxial and Direct Shear Methods for Undisturbed Dense Sand

Obtaining representative samples for laboratory shear strength testing forms the foundation of a successful geotechnical investigation program. The selection of suitable laboratory testing methods and the understanding of their limitations in the mining of a mineral sands deposit is discussed. The pit slopes will comprise of cohesionless sand and silty sand. The method of recovering undisturbed samples in a deep drilling program is outlined. The use of undisturbed samples increases confidence and reliability in probabilistic stability analysis. The effective friction angle values from 40 consolidated undrained triaxial and 46 direct shear tests are compared. The direct shear test results are 5% lower than the triaxial test results due to subhorizontal bedding. In addition, the coefficient of variation for the triaxial and direct shear friction angle results are 4.3% and 9% respectively, indicating a larger dispersion in the direct shear test results. The triaxial and direct shear datasets result in distinctly different outcomes for pit slope optimisation studies with substantial financial implications. Incorporating triaxial test data in a 35° pit slope stability assessment results in a 36% higher confidence level of achieving or exceeding a factor of safety of 1.3, relative to using the direct shear test data.

Stability Analysis and Support Design Methods for Rock Foundation Pit with Combination of Structural Plane and Karst Cave

In this paper, the failure mode of the “deep foundation pit slope with high dip angle structural surface and cave development” is analyzed by numerical simulations, and an innovative numerical calculation method for calculating the stability of foundation pit slope based on the principle of upper limit analysis and the prediction method of rock slope surface is proposed. The lateral earth pressure acting on the support structure is further deduced, which can be used more widely than the traditional earth pressure calculation equations. Based on finite element analysis of a pole system, we developed an improved numerical calculation method of the force, and deformation of retaining piles is proposed to carry out the analysis of the deformation of structures under force. Our method avoids the need to artificially place earth pressure on either side of the embedded portions of the piles. Compared with the measured horizontal displacement of the retaining pile, this improved numerical calculation method can reflect the force and deformation law of retaining piles at certain construction stages. In this paper, the upper limit analysis method based on the stability analysis of slopes and earth pressure calculation equations is proposed, taking into account the working conditions of the karst cave in different locations, and the minimum supporting force required can be calculated more accurately while predicting the range of slope sliding surface. An improved numerical calculation method of the retaining piles is proposed in this paper, and the calculation results can reflect the deformation law of the retaining piles during the excavation of the rock foundation pit, and the whole analysis and calculation process has certain advantages compared with the traditional method.

Groundwater Effect on Slope Stability in Open Pit Mining: a Case of West Kutai Regency, East Kalimantan, Indonesia

The stability of open pit slopes in Biangan district, West Kutai Regency, East Kalimantan Province, is greatly influenced by groundwater conditions. The existence of groundwater reduces the shear strength of the materials which causes a decrease in the stability value of pit slopes. The main objective of this study is to assess the impact of groundwater on the stability of the low wall and high wall pit mining. Groundwater modeling is used to determine the prediction of groundwater level on the pit slope which determines the value of the slope stability. Slope stability analysis in this study was performed using the Finite Element Method, producing output in the form of strain zones, deformation and displacement values. Therefore, the Strength Reduction Factor (SRF) approach was used, which is a gradual reduction of shear strength until the values of cohesion and friction angles reach minimums and the slopes are at a critical state. Groundwater modeling results indicate that groundwater flows to the Biangan river with hydraulic heads between 76 and 108 meters above sea level. Based on the analysis using the Finite Element Method, the stability values of the pit slopes, which are influenced by groundwater, are 0.65 on the low wall and 1.40 on the high wall. The total displacements are 0.019 meters on the low wall and 0.002 meters on the high wall. The impact of groundwater on the slope is an increase in the slope load. This increases the materials’ thrust and reduces the shear strength of the materials which reduces the rock mass that can function as a water seepage path. Thus, the recommendation for low wall pit construction is a safety factor of 7.79 with a total displacement of 0.020 meters.

The analysis of computer aided methods applied for pit wall stability rating

A comparative analysis of the results of the pit slope stability rating carried out under normative technique and Scad Office Slope application is presented. The possibility of combination of normative technique and computerized calculations to gain integrity and computation operability is suggested.

Effect of Blast-induced Ground Vibration on Factor of Safety of Pit Wall Stability

The regulated maximum peak particle velocity (PPV) from blasting operations of an open-pit coal mine is less than 2 mm/s to prevent mainly any public disturbance such as ground vibration and air blast. However, the blast-induce ground vibration can also decrease the stability of pit slope, which has not been intensively studied. A claystone pit wall, which is geotechnically investigated as having a plane failure type and the natural condition factor of safety (FS), has been selected for this study. The FS is selected to measure the effect of blast-induced ground vibration on the slope stability. The limit equilibrium, pseudo-static 1 (), and pseudo-static 2 () methods are used to determine the FS. The vibration results of blasting monitored at three slope positions: crest, middle, and toe, from two areas at the same pit wall, are recorded by blasting seismographs. Maximum charge weight per delay and the distance from blast areas to seismographs are collected to construct the scaled distance. The percentage change of FS of three methods from both areas compared to natural condition FS are all less than 4 percent considered that the slope stability is safe from blasting vibration (less than 15 percent). The relationship between the FS and maximum PPV from the limit equilibrium, pseudo-static 1 (), and pseudo-static 2 () methods indicate that the adverse maximum PPVs given the unity FS are 16.60 and 4.58, and 4.74 mm/s, respectively. The regulated PPV less than 2 mm/s at the mine is reasonable to prevent any possible plane failure. However, many impact parameters have not been included in this study, and their effects may disturb the pit wall stability.

Application research on slope deformation monitoring and earthwork calculation of foundation pits based on UAV oblique photography

The stability of foundation pit slopes is a key concern during the construction of foundation pits. The deformation and instability of slopes will pose a major threat to the safety of foundation pits construction. Based on the foundation pit project of Shenzhen Dapeng People’s Hospital, this study uses DJI phantom 4 RTK drone to collect oblique photography data of the foundation pit in different periods, reconstructs high-precision 3D virtual models through the Bentley ContextCapture software and generates the Digital Surface Model (DSM) data. The model quality report shows that the accuracy of the three-dimensional model is better than 5 cm, up to about 1 cm. Spatial analysis of DSM data in different periods using ArcGIS can obtain the deformation of the foundation pit slopes. This method can also be used for the calculation of earthwork excavation of the foundation pit, which can effectively reduce the field workload of traditional earthwork surveys.

METHODOLOGY OF INSTRUMENTAL CONTROL OF STABILITY OF QUARRY SLOPES USING GNSS TECHNOLOGIES

The article describes the methodology of instrumental monitoring of the stability of Karatemir open pit slopes using GNSS technologies. An iron ore deposit was selected to carry out the study. The exploitation of subsurface use facilities developed in an open way requires regular monitoring of the stability state of the instrument array. This is the main task for the safe and efficient operation of the entire field. The favorable conditions for conducting observations and the accuracy of satellite observations are also described. The analysis of the stability status of career slopes.

Step-by-step investigation of engineering and geological conditions of mineral deposits for safe mining

Introduction. Engineering and geological processes as a result of process operation at deposits often develop at an exponential rate. This problem is specific due to complex and multifactorial nature of the processes which arise when rock mass interacts with mine workings. For this reason engineering and geological information should be obtained step by step beginning with the stage of prospecting and evaluation and proceeding at the stages of construction and operation of mine workings. Research aim is to consider methodological basis to form the databases of geological engineering information about mining facilities at various stages of their life cycle. Research methodology. The types of operations have been described on acquisition and interpretation of engineering-geological information required to detail models of the engineering-geological conditions at every stage. An important factor in creating a reliable and functioning geomechanical model of mineral deposits is survey operations follow-up and gradual transition from regional and provincial engineeringgeological conditions and tectonic structure to engineering-geological conditions of a specific deposits or occurrence. Research results. By the example of chrome field located in the Polar Urals within the Rai-Iz massif, all detail stages of mineral deposits engineering-geological conditions model have been established taking into account the conditioning selected components and factors; possible problems have been described and the results of step-by-step predictive estimates of mine workings stability have been presented. Summary. The research present an example of engineering-geological data detailing by the results of the gamma ray log and caliper logging at the stages of pit slope stability forecast model construction. Obtained in the course of long-term data collecting and processing, the model of Tsentralnoe field has proved its efficiency in the course of mining.

Numerical investigations of rock bridge effect on open pit slope stability

Abstract In this study, the effect of rock bridges on rock slope stability was investigated by incorporating non-persistent joint networks in numerical models, and the critical profiles of an open pit mine were analysed. Parallel deterministic networks of infinite and finite lengths, ubiquitous joint network model and Veneziano joint network model were used in order to simulate the rock fractures. Materials were modelled based on the generalised Hoek―Brown and equivalent Mohr–Coulomb failure criteria. The parallel deterministic infinite and the ubiquitous joint network models produced lower safety factors. The introduction of rock bridges along discontinuity planes in the parallel deterministic network and Veneziano joint network models significantly contributed to the stability and strain distribution, which should be considered in stability analysis of rock mass in open pit by rock slope practitioners. The results show the significance of joints in hard rock behaviour and the joints should be included in order to attain practical and realistic simulations.

The angles optimization algorithm of slopes laying on iron ore open cast mine considering anisotropy of strength properties and fracture density of the solid rock (on the example of Stoylensky iron ore open cast mine at Kursk Magnetic Anomaly)

Система комплексной поддержки и сопровождения научного журнала Elpub позволяет запустить двуязычный сайт журнала со встроенной системой электронной редакции в соответствии с лучшими издательскими практиками, а так же предусматривает техническую и методическую поддержку со стороны специалистов НЭИКОН.

Automatic analysis of pit slope stability in clays of quaternary sediments

Automatic analysis of pit slope stability in clays of quaternary sediments

Analytical and Numerical Approach for Analysis of Factors Affecting Pit Slope Stability at Dorli OCP-Ii, India

In order to determine the slope stability of an open-pit mine effectively at Dorli Opencast Project-II (Dorli OCP-II) of M/s Singareni Collieries Company Ltd. (SCCL), India, from available geotechnical data, this paper proposes analytical and numerical models. Physico-mechanical properties of the rock materials required for establishing these models were obtained by laboratory tests conducted on core samples taken directly from the mine. In this research, the influence of 6 discriminant factors on the pit stability by changing one-factor-at-a-time (OAT) and keeping all other factors fixed is studied. The study utilizes Limit Equilibrium Method (LEM) based software (SLIDE), Finite Element Method (FEM) based software (RS2) and Finite Difference Method (FDM) based software (FLAC/SLOPE) to analyze the sensitivity of each factor on the Factor of Safety (FoS) of pit slope for high accuracy and validation of models. The results from these methods of analyses are compared and comparison of the outputs of analyses shows a very good agreement with nominal difference (<1%) in the FoS.