Numerical Investigation of Caved Rock Mass Friction and Fragmentation Change Influence on Gravity Flow Formation in Sublevel Caving

Lapčević, Veljko; Torbica, Slavko

doi:10.3390/min7040056

Cited by 13 publications

(8 citation statements)

References 24 publications

(25 reference statements)

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“…According to (1) and (2), the curves of subsidence and subsidence rate are shown in the solid line in Figure 6(d), where the fitting curve basically agrees with the monitoring result. The above expression can provide guidance for the dynamic prediction of the process of surface subsidence.…”

Section: Monitoring Of Surface Movement and Subsidencesupporting

confidence: 72%

“…There are a large number of iron ore resources in the northeastern part of China, and the total reserves of these resources account for two-fifths of the national gross proved reserves. Due to the influence of geological conditions, orebody distribution characteristics, and mining technology, most of these underground iron mines are mined by the sublevel caving method [1][2][3], which is characterized by extraction on a large scale and high production efficiency with low mining cost. However, sublevel caving mining inevitably results in the formation of underground goafs [4], and the existence of underground goafs will cause the imbalance and redistribution of the stress around the opening, which will cause the displacement, deformation, and failure of the roof strata [5,6].…”

Section: Introductionmentioning

confidence: 99%

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Study on the Rock Mass Caving and Surface Subsidence Mechanism Based on an In Situ Geological Investigation and Numerical Analysis

Ren

Zhang

Cao

et al. 2018

Mathematical Problems in Engineering

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To deeply understand the mechanism of the rock mass caving and associated surface subsidence during sublevel caving mining, the Xiaowanggou iron mine was selected as an engineering project case study. The study area was analyzed by means of an in situ geological investigation and numerical simulation. First, a borehole television (BHTV) system and a GPS monitoring system were used to monitor the caving process of the roof rock mass and the development of the surface subsidence; the monitoring time was thirteen months. Then, a numerical simulation was used to analyze the damage evolution of the rock mass. Research shows the following: (1) in situ geological monitoring results indicate that the caving process of the roof rock mass presents intermittent characteristics, where slow caving and sudden caving are conducted alternatively and the arched-caving trend is more pronounced with continuous mining. The surface subsidence, horizontal displacement, and horizontal deformation of the hanging wall are higher than that of the footwall, and the subsidence center gradually deflects to the hanging wall in the late stage of the +45m sublevel mining. (2) Numerical simulation results indicate that the extension and penetration of the shear and tensile cracks along the joints and intact rock bridges are the main factors causing the rock mass caving and the existence of the stress arch and its evolution process is the fundamental reason for the intermittent caving of the rock mass. The rapid development of damage to the hanging wall (the damage angle reduced) is the main cause of the deflection of the subsidence center affected by joints and the mining size. (3) In the future of mining, large-scale subsidence will occur on the surface of the hanging wall.

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Section: Monitoring Of Surface Movement and Subsidencesupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Study on the Rock Mass Caving and Surface Subsidence Mechanism Based on an In Situ Geological Investigation and Numerical Analysis

Ren

Zhang

Cao

et al. 2018

Mathematical Problems in Engineering

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“…Campbell and Power (2017) used the CA flow software and a blast mobility factor to calibrate a flow model using measured marker recovery and to calibrate flow and recovery at a ring scale. Lapcevic & Torbica (2017) numerically investigated the caved rock mass friction and fragmentation change influence on the gravity flow formation in sublevel caving with 'Yade' code (Šmilauer 2020).…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of fragmentation by blasting and gravity flow in sublevel caving mines

Yi¹,

Johansson²,

Wimmer³

et al. 2022

Caving 2022: Fifth International Conference on Block and Sublevel Caving

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The sublevel caving (SLC) mining method is based on the utilisation of gravity flow of blasted ore and caved waste rock. Blasting is the initial and the major impact upon primary fragmentation and later material flow characteristics. A coupled numerical model was employed to investigate the fragmentation due to blasting and the gravity flow using the LS-DYNA code. In the coupled model, a loose discrete element model (DEM) was used to represent caved waste rock and a bonded DEM model was used to represent the orebody to be blasted, a particle blast method (PBM) was used to describe the detonation of explosive and a finite element model (FEM) was used to model the remaining orebody. The cumulative dilution of the ore by waste during extraction was evaluated. The results showed that the fragments at the upper part of the ring are coarse while the fragments at the lower part of the ring are fine. The change of the cumulative dilution along with the extraction is reasonable.

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“…Beside ore properties, caved waste material has high impact on dilution of the ore. Influence of strength, friction and fragmentation change in caved waste material has been numerically investigated (DeGagne, et al, 2006;Lapčević & Torbica, 2017) while there is lack of in-situ reports on this subject. In general, caved material with lower friction angle will move faster, with lower frictional kinematic resistance, and will influence the greater dilution of ore.…”

Section: Introductionmentioning

confidence: 99%

“…It is based on determination of particle velocities from stress distribution and provides best results in evenly grained materials. Discrete element method (DEM) has been successfully used for numerous simulations of granular material flow and as such for sublevel caving (Selldén & Pierce, 2004;DeGagne & others, 2005;DeGagne, et al, 2006;Lapčević & Torbica, 2017). DEM models provide very useful tool for gravity flow modelling since it is possible to investigate influence of different parameters that are normally hard to analyze in physical tests.…”

Section: Introductionmentioning

confidence: 99%

Influence of boundary conditions in DEM models of sublevel caving on dilution and recovery

et al. 2018

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Discrete element modelling is common approach for analysis of dynamical processes that include granular materials. Method is commonly applied for the modeling of the gravity flow of the broken rock in caving operations. Herein, comparison of two different approaches in such modelling was presented. Two models, ring wide and symmetrically divided, were used for comparison. Ore dilution and recovery were monitored as main comparison parameters, but also the processing time of such models and spatial shape of extraction zones. Ring wide model show greater ore dilution and lower recovery, while half wide models show the opposite results. Cumulative dilution differs for 10%, while ore recoveries differ in approximately 15% for same extraction levels. Also, dilution entrance points are different, where ring wide model shows earlier dilution entrance at about 15% of extraction, while dilution enters at 25% in half wide models. Processing speed is increased in half wide model due to the reduction in number of elements, but overall processing time is nearly the same due to the frequent hang ups inside the half wide model. Shape and size of the extraction zones are very different. Half wide model shows much higher extraction zone in contrary with ring wide, while depth of extraction zone is greater in ring wide models which corresponds with higher and earlier entry of dilution.

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Numerical Investigation of Caved Rock Mass Friction and Fragmentation Change Influence on Gravity Flow Formation in Sublevel Caving

Cited by 13 publications

References 24 publications

Study on the Rock Mass Caving and Surface Subsidence Mechanism Based on an In Situ Geological Investigation and Numerical Analysis

Study on the Rock Mass Caving and Surface Subsidence Mechanism Based on an In Situ Geological Investigation and Numerical Analysis

Numerical modelling of fragmentation by blasting and gravity flow in sublevel caving mines

Influence of boundary conditions in DEM models of sublevel caving on dilution and recovery

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