scholarly journals Study on Blasting Technology for Open-Pit Layering of Complex Mine Adjacent to High and Steep Slope

2021 ◽  
Vol 9 ◽  
Author(s):  
Menglai Wang ◽  
Xiaoshaung Li ◽  
Qihang Li ◽  
Yunjin Hu ◽  
Qiusong Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Oblique Line ◽  
Field Tests ◽  
Mining Area ◽  
Open Pit ◽  
Blasting Vibration ◽  
Mass Rate ◽  
Propagation Law ◽  
Steep Slopes

In China, mining blasting vibration has seriously threatened the safety and stability of high and steep rock slopes. In this paper, taking the east mining area of Jianshan Phosphorus Mine as the research background, combined with field survey, field blasting test, numerical simulation and theoretical analysis, we systematically studied the adjacent high-steep rock slope and the layered blasting technology of complex ore. Based on wide hole spacing blasting numerical simulation and field tests, the use of 8 × 4 m hole network parameters, oblique line hole-by-hole initiation method, detonator delay using 35 ms between holes, 65 ms between rows and 500 ms within the holes, the rock mass rate was reduced and the drilling workload was decreased. In addition, regression analysis was carried out on a large amount of vibration test data, and the attenuation law and propagation law of blasting vibration of adjacent high and steep slopes were predicted, which provided a reference for mine production blasting. By establishing a mathematical model of cumulative damage of rock mass blasting, it shows that the depth of impact of mining blasting on the slope of Jianshan open-pit was 0–3.6m, but the blasting did not cause overall damage to the adjacent high and steep slopes. In the future, this model can be used to predict rock damage caused by subsequent blasting.

scholarly journals Determination of the Ultimate Underground Mining Depth considering the Effect of Granular Rock and the Range of Surface Caving

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Rongxing He ◽  
Jing Zhang ◽  
Yang Liu ◽  
Delin Song ◽  
Fengyu Ren
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Mechanical Model ◽  
Surface Deformation ◽  
Underground Mining ◽  
Mining Area ◽  
Open Pit ◽  
Open Pit Mining ◽  
Mining Depth

Continuous mining of metal deposits leads the overlying strata to move, deform, and collapse, which is particularly obvious when open-pit mining and underground mining are adjacent. Once the mining depth of the adjacent open-pit lags severely behind the underground, the ultimate underground mining depth needs to be studied before the surface deformation extends to the open-pit mining area. The numerical simulation and the mechanical model are applied to research the ultimate underground mining depth of the southeast mining area in the Gongchangling Iron mine. In the numerical simulation, the effect of granular rock is considered and the granular rock in the collapse pit is simplified as the degraded rock mass. The ultimate underground mining depth can be obtained by the values of the indicators of surface movement and deformation. In the mechanical model, the modified mechanical model for the progressive hanging wall caving is established based on Hoke’s conclusion, which considers the lateral pressure of the granular rock. Using the limiting equilibrium analysis, the relationship of the ultimate underground mining depth and the range of surface caving can be derived. The results show that the ultimate underground mining depth obtained by the numerical simulation is greater than the theoretical calculation of the modified mechanical model. The reason for this difference may be related to the assumption of the granular rock in the numerical simulation, which increases the resistance of granular rock to the deformation of rock mass. Therefore, the ultimate underground mining depth obtained by the theoretical calculation is suggested. Meanwhile, the surface displacement monitoring is implemented to verify the reasonability of the ultimate underground mining depth. Monitoring results show that the indicators of surface deformation are below the critical value of dangerous movement when the underground is mined to the ultimate mining depth. The practice proves that the determination of the ultimate underground mining depth in this work can ensure the safety of the open-pit and underground synergetic mining.

General concept of determining the parameters of non-mining walls of ultra-deep diamond deposits development open pits

2021 ◽  
pp. 48-53
Author(s):  
I. V. Zyryanov ◽  
A. N. Akishev ◽  
I. B. Bokiy ◽  
N. M. Sherstyuk
Keyword(s):  
Rock Mass ◽  
Structural Relaxation ◽  
Slope Angle ◽  
Field Tests ◽  
Friction Angle ◽  
Strength Properties ◽  
Strength Characteristics ◽  
Open Pit ◽  
Open Pit Mining ◽  
Relaxation Coefficient

A specific feature of open pit mining of diamond deposits in Western Yakutia is the construction of the open pits in the zone of negative ambient temperatures, which includes thick permafrost rock mass, and which is at the same time complicated by the influence of cryogenic processes on deformation of pit wall benches. The paper presents the comparative analysis of strength characteristics in frozen and thawed rocks, stability of benches during mining, the general geomechanical approach to the determination of parameters of non-mining walls of the ultra-deep open pit diamond mines, and the parameters of nonmining walls and benches. Optimization of open pit wall configuration should primarily be based on the maximum utilization of the strength properties of frozen rocks in combination with the development of new approaches, calculation schemes and methods for assessing stability of open pit walls and benches of unconventional design, including the non-mining vertical benches. The main design characteristic that determines the parameters of open pit walls is the structural tectonic relaxation coefficient, which specifies the calculated value of cohesion in rock mass. For the diamond deposits, the values of the structural relaxation coefficient were obtained in a series of field tests and back calculations. Full-scale tests were carried out both during exploration operations in underground mines and in open pits. The accuracy of determining the values of the structural relaxation coefficient in the range of 0.085–0.11 is confirmed by the parameters of non-mining walls in an open pit mine 385–640 m deep, with overall slope angles of 38–55° and a steeper H 0.35–0.5 lower part having the slope angle of up to 70° with average strength characteristics of 7.85–11.84 MPa and the internal friction angle of 28.1–37.4°. Using the natural load-bearing capacity of rock mass to the full advantage, which the values of the structural relaxation coefficient of deposits show, allows optimization of open pit wall slope design and minimization of stripping operations.

Rock Mass Deformation Characteristics in High-Steep Slopes Influenced by Open-Pit to Underground Mining

2016 ◽  
Vol 34 (3) ◽  
pp. 847-866 ◽  
Author(s):  
Chuanbo Zhou ◽  
Shiwei Lu ◽  
Nan Jiang ◽  
Dingbang Zhang ◽  
Zhihua Zhang ◽  
...  
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Open Pit ◽  
Deformation Characteristics ◽  
Rock Mass Deformation ◽  
Steep Slopes ◽  
Mass Deformation

scholarly journals Two-Dimensional Modeling of the Influence of Underground Mining Direction on Slope Stability in Coordinated Open-Pit and Underground Mining

2021 ◽  
Author(s):  
Bowen Liu ◽  
Zhenwei Wang ◽  
Xinpin Ding ◽  
Zhitao Wang ◽  
Bin Li
Keyword(s):  
Rock Mass ◽  
Slope Stability ◽  
Underground Mining ◽  
Mining Area ◽  
Two Dimensions ◽  
Open Pit ◽  
Engineering Practice ◽  
Inverse Slope ◽  
Coal Wall ◽  
Mining Face

Abstract Under a background of coordinated open-pit and underground mining engineering practice in the Pingshuo mining area, a combination of numerical simulations and similar-model experiments was used to study the influence of the underground mining direction on slope deformation in two dimensions. The results show that the disturbance caused by inverse-slope mining is more obvious than that caused by along-slope mining. Underground mining presents an asymmetric influence on the open-pit slope; the slope rock mass on the open-off cut side is disturbed more than that on the coal-wall side. Compared with the slope in front of the advancing direction of the underground mining face, the degree of rock-mass damage and stress concentration of the slope of the open-off cut side are more serious. As such, in coordinated open-pit and underground mining practice, an along-slope mining direction is recommended to reduce adverse effects on slope stability and improve the recovery rate of coal resources.

scholarly journals Onsite Tests and Numerical Simulation of Broken Rock Zones in Surrounding Rocks of Seepage Roadways under Blasting

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Zhouyuan Ye ◽  
Kun Pan ◽  
Zhihua Zhou
Keyword(s):  
Numerical Simulation ◽  
Shear Failure ◽  
Mechanical Response ◽  
Water Pressure ◽  
Mining Area ◽  
Seepage Water ◽  
Blasting Vibration ◽  
Fracture Density ◽  
Iron Mine ◽  
Ground Stress

To study the influence of blasting vibration on the broken rock zone around a seepage roadway and provide guidance for design of the roadway support, the broken rock zones around rock of seepage roadways under production blasting vibration are determined by onsite tests in a mining area, Daye iron mine. During the testing process, it is found that blasting vibration causes internal cracks of surrounding rocks to initiate and develop, the fracture density increases, the acoustic wave velocity of rock mass decreases, and the broken rock zones expand. At the same time, through onsite observation, it is found that blasting vibration results in crack development and formation of a water pathway to lead to surface water into the ground. The mechanical response around rock of the seepage roadway under blasting vibration is simulated by the two-dimensional realistic fracture progress analysis calculation software (RFPA2D). It is found that internal cracks of roadway surrounding rock initiate, propagate, and join up gradually, and the fracture range is expanding under the seepage water pressure, ground stress, and cyclic loads, and the broken rock zones also expand. The results from numerical simulation are consistent with the results of onsite tests. It is also found that the tensile stress appears around some cracks, leading to part of the cracks more likely to generate shear failure under the seepage water pressure during simulation.

scholarly journals Prediction of Blasting Vibration Velocity of Layered Rock Mass under Multihole Cut Blasting

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jie Zhu ◽  
Haixia Wei ◽  
Xiaolin Yang ◽  
Huaibao Chu
Keyword(s):  
Differential Equation ◽  
Rock Mass ◽  
Prediction Accuracy ◽  
Time History ◽  
Vibration Velocity ◽  
Blasting Vibration ◽  
Underground Engineering ◽  
Layered Rock ◽  
Propagation Law ◽  
Layered Rock Mass

In the blasting construction of underground engineering in layered rock mass, the mechanism of cut blasting and the propagation law of blasting vibration waves are very complex. In this paper, a new method for predicting the blasting vibration velocity of layered rock mass under multihole cut blasting is proposed. The key steps include determining the equivalent elastic boundary and load, establishing the multidegree freedom model of blasting vibration and its motion differential equation, and solving the motion differential equation by time-history analysis method. Two multihole cut blasting tests of different schemes were carried out in the construction site of layered rock mass, and the measured results of blasting vibration waves were obtained. By comparing the time-history curves of the predicted and measured blasting vibration velocity, it can be seen that the time-history curves predicted by the proposed method can reflect the characteristics and attenuation law of blasting vibration waves, and the predicted waveforms are similar to the measured waveforms. By using the proposed method, the prediction accuracy for the peak velocity of blasting vibration in the two tests is 93% and 94%, respectively, and the prediction accuracy for the dominant frequency of blasting vibration in the two tests is 86% and 94%, respectively. The prediction accuracy of the main characteristic parameters of blasting vibration waves is high. So it can be proved that the prediction method proposed in this paper is feasible in effectiveness and accuracy, which can provide important theoretical guidance for the optimization of blasting design and the control of blasting vibration in underground engineering in layered rock mass.

Study on the Rockmass Instability of Open-Pit Mine by Block Theory and Numerical Simulation Methods

2013 ◽  
Vol 353-356 ◽  
pp. 1077-1081
Author(s):  
Hai Gang Li ◽  
Zhi Jun Yang ◽  
Tong Lin Han
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Finite Difference ◽  
Surrounding Rock ◽  
Open Pit ◽  
Rock Mechanic ◽  
Mining District ◽  
Lagrangian Analysis ◽  
Rock Mass Structure ◽  
Block Theory

On the background of rock masses and field engineering geology of a mine, the feature of rock mechanics and rock mass structure of surrounding rock at mining district are analyzed. Based on the finite difference theory and block theory, FLAC3D program (Fast Lagrangian Analysis for Continuum), rock mechanic and rock mass structure results are used to construct the finite difference mechanical model, which reflected the surrounding rock stability when mining. By the numerical simulation, the mechanical effect is studied by the process of mining and its results can be used to produce some theory and actual basis.

scholarly journals Vibration Safety Criteria for Surficial Rock Mass of Open Pit Slope Affected by Underground Mining Blasting Operations

2017 ◽  
Vol 11 (1) ◽  
pp. 627-637 ◽  
Author(s):  
Nan Jiang ◽  
Chang Xiong ◽  
Chuanbo Zhou ◽  
Xuedong Luo ◽  
Shiwei Lu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Underground Mining ◽  
Ultimate Tensile Stress ◽  
Stress Waves ◽  
Open Pit ◽  
Vibration Velocity ◽  
Blasting Vibration ◽  
Stress Criterion ◽  
The North ◽  
South Slope

Introduction: Blasting vibration velocity is an important index to evaluate the stability of mine slopes under blasting operations. Objective: In order to determine the blasting vibration safety criteria for slope rock mass scientifically and reasonably, the influence of stress waves on surficial rock mass of mine slopes was analyzed when stress waves propagate to the slope surface, and mathematical models for blasting vibration safety criteria are proposed based on the ultimate tensile stress criterion, the ultimate shear stress criterion and the Mohr-Coulomb criterion. Results and Conclusion: Combined with the field blasting operations during the open-pit to underground mining in Daye iron mine, the blasting vibration safety criteria is calculated. It is obtained that the blasting vibration safety criteria for the north slope and the south slope are 11.08cm/s and 10.20cm/s respectively. The results agree well with the Safety Regulations for Blasting in China and provide a reference to determine blasting vibration safety criteria for other similar projects.

scholarly journals Assessment of Blasting-Induced Ground Vibration in an Open-Pit Mine under Different Rock Properties

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Zhi-qiang Yin ◽  
Zu-xiang Hu ◽  
Ze-di Wei ◽  
Guang-ming Zhao ◽  
Ma Hai-feng ◽  
...  
Keyword(s):  
Rock Mass ◽  
Ground Vibration ◽  
Open Pit Mine ◽  
Vibration Monitoring ◽  
Open Pit ◽  
Blasting Vibration ◽  
Vibration Frequencies ◽  
Rock Masses ◽  
Vibration Signals ◽  
Modified Equation

In an open-pit mine slope, rock mass has multiple joint structures and blasting operations have an obvious influence on its stability. Therefore, accurately predicting the blasting vibration is necessary to ensure slope stability. In this study, the blasting vibration signals monitored at a blasting site with different rock masses were used to investigate the attenuation characteristics of blasting vibration through the peak particle velocity (PPV), frequency characteristics, and energy distribution of the blasting vibration signals analyzed with the time-frequency processing method. The results demonstrated that the main vibration frequency of the blasting vibration of dolomite was wider than that of shale, and these main vibration frequencies occurred at 25 kHz and 14 kHz for dolomite and shale, respectively, at a distance of 50 m from the blast area to the vibration monitoring point. With an increase in the distance from 50 m to 200 m, the main vibration frequencies decreased to less than 5 Hz. With increasing joint degree, the attenuation rate of the vibration velocity and energy attenuation of the blasting vibration increase, indicating that the structural parameters of the rock mass (such as the number of joints) have a significant impact on the attenuation law of blasting vibration. Furthermore, a modified equation that can be used for predicting PPV was developed by considering the effect of the number of joints in the rock mass on the blasting vibration. For the same ground vibration readings, the correlation factor increased from 0.8 to 0.85 for the Nicholls-USBM equation and the modified equation, respectively. The PPV of blasting under different rock masses of the Baideng open-pit phosphorite mine was used to verify the modified equation. The results show that a modified equation can be used for predicting the PPV of blasting engineering in the Baideng phosphorite mine and that the prediction accuracy is acceptable.

scholarly journals A New Mathematical Model for Predicting the Surface Vibration Velocity on the Step Topography

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Xu Wu ◽  
Qifeng Guo ◽  
Yunpeng Zhang
Keyword(s):  
Mathematical Model ◽  
Measured Data ◽  
Open Pit ◽  
Vibration Velocity ◽  
Amplification Coefficient ◽  
Blasting Vibration ◽  
Attenuation Effect ◽  
Amplification Effect ◽  
Propagation Law ◽  
Terrain Effect

In order to control production blasting and optimize mining operation, it is important to study the step topography vibration amplification and attenuation effect in the open-pit mine. Surface particle vibration velocity attenuation characteristics, the formation, and change rules of the terrain effect were studied by analyzing the field measured data. Results show that local amplification effect and local attenuation amplification effect of particle vibration velocity are obvious. Amplification effect associates with bench height, and the attenuation effect is closely related with the distance from the vibration source and distance from the top. With the increase of elevation, vibration magnification of the particle on the top was 1.1∼1.4. Because of the influence of the terrain effect, particle vibration velocity on the slope toe was obviously inhibitory. Based on the measured data, elevation amplification factor and clamping effect factor which influence blasting vibration velocity are put forward, and a new mathematical model considering the attenuation coefficient, the elevation amplification coefficient, and the clamping effect coefficient for predicting the blasting vibration velocity of the step topography is further improved. The regression analysis results show that the fitting coefficient of determination of the new prediction model is 0.8152 in horizontal and 0.8902 in vertical, respectively, and the prediction error is less than 20%, which is much better than other formulas. This new model provides effective reference for blasting seismic wave propagation law research of slope engineering.

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