scholarly journals Rock Fall Hazard Analysis for In-Pit Operations Potentially Impacting External Sensitive Areas

Mining ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 135-154
Author(s):  
Renato Macciotta ◽  
Frank Altamirano ◽  
Lachlan Gibbins ◽  
Marco Espezua ◽  
Rubén Fernández ◽  
...  
Keyword(s):  
Hazard Analysis ◽  
Three Dimensional ◽  
Mitigation Strategies ◽  
Open Pit ◽  
Peruvian Andes ◽  
Rockfall Hazard ◽  
Geometry Design ◽  
Steep Terrain ◽  
Rockfall Mitigation ◽  
Rockfall Protection Structures

Controlling rockfall-related risks is a requirement for safe pit operations and primarily mitigated through adequate bench geometry design and implementation. This paper presents a method for rockfall hazard analysis for in-pit operations potentially impacting external sensible areas, adapted from natural rockfall hazard analyses. The method considers the natural susceptibility to rockfalls pre-mining, rockfalls originated from bench failures, and those initiated as flyrock. Rockfall trajectory models are used to estimate the potential for blocks reaching exposed elements. Natural susceptibility to rockfalls and trajectories are used as a baseline on which to evaluate the potential effects of open pit operations on the environment and perceptions of communities in the area. The method is illustrated for an open pit in steep terrain in the Peruvian Andes at a feasibility level of study. The paper illustrates the flexibility for including considerations of pre-mining rockfall impacts on the external elements of interest, and for developing rockfall mitigation strategies that consider rock block velocities, heights, energies and the spatial distribution of trajectories. The results highlight the importance of considering the three-dimensional effects of the terrain on block trajectories, and how such insights allow for increasing the efficiency of resources available for rockfall protection structures.

scholarly journals Significance of substrate soil moisture content for rockfall hazard assessment

2019 ◽  
Author(s):  
Louise M. Vick ◽  
Valerie Zimmer ◽  
Christopher White ◽  
Chris Massey ◽  
Tim Davies
Keyword(s):  
Moisture Content ◽  
Material Properties ◽  
Initial Conditions ◽  
Hazard Analysis ◽  
Three Dimensional ◽  
Soil Conditions ◽  
Loessial Soil ◽  
Runout Distance ◽  
Rockfall Hazard ◽  
Strength And Stiffness

Abstract. Rockfall modelling is an essential tool for hazard analysis in steep terrain. Calibrating terrain parameters ensures that the model results accurately represent the site-specific hazard. Parameterizing rockfall models is challenging because rockfall runout is highly sensitive to initial conditions, rock shape, size and material properties, terrain morphology, and terrain material properties. This contribution examines the mechanics of terrain scarring due to rockfall on the Port Hills of Christchurch, New Zealand. We use field-scale testing and laboratory direct-shear testing to quantify how the changing moisture content of the loessial soils can influence its strength from soft to hard, and vice versa. We calibrate the three-dimensional rockfall model RAMMS by back analysing several well-documented rockfall events, adopting dry loessial soil conditions. We then test the calibrated dry model by adopting wet loessial soil conditions. The calibrated dry model over-predicts the runout distance when wet loessial soil conditions are assumed. We hypothesis that this is because both the shear strength and stiffness of wet loess are reduced relative to the dry loess, resulting in a higher damping effect on boulder dynamics. For realistic and conservative rockfall modelling, the maximum credible hazard must be assumed; for rockfall on loess slopes, the maximum credible hazard occurs during dry soil conditions.

scholarly journals Significance of substrate soil moisture content for rockfall hazard assessment

2019 ◽  
Vol 19 (5) ◽  
pp. 1105-1117 ◽  
Author(s):  
Louise Mary Vick ◽  
Valerie Zimmer ◽  
Christopher White ◽  
Chris Massey ◽  
Tim Davies
Keyword(s):  
Moisture Content ◽  
Material Properties ◽  
Initial Conditions ◽  
Hazard Analysis ◽  
Three Dimensional ◽  
Soil Conditions ◽  
Loessial Soil ◽  
Runout Distance ◽  
Rockfall Hazard ◽  
A Site

Abstract. Rockfall modelling is an important tool for hazard analysis in steep terrain. Calibrating terrain parameters ensures that the model results more accurately represent the site-specific hazard. Parameterizing rockfall models is challenging because rockfall runout is highly sensitive to initial conditions, rock shape, size and material properties, terrain morphology, and terrain material properties. This contribution examines the mechanics of terrain impact scarring due to rockfall on the Port Hills of Christchurch, New Zealand. We use field-scale testing and laboratory direct shear testing to quantify how the changing moisture content of the loessial soils can influence its strength from soft to hard, and vice versa. We calibrate the three-dimensional rockfall model RAMMS by back-analysing several well-documented rockfall events that occurred at a site with dry loessial soil conditions. We then test the calibrated “dry” model at a site where the loessial soil conditions were assessed to be wet. The calibrated dry model over-predicts the runout distance when wet loessial soil conditions are assumed. We hypothesize that this is because both the shear strength and stiffness of wet loess are reduced relative to the dry loess, resulting in a higher damping effect on boulder dynamics. For both realistic and conservative rockfall modelling, the maximum credible hazard is usually assumed; for rockfall on loess slopes, the maximum credible hazard occurs during dry soil conditions.

scholarly journals Installation Uncertainty of Field Level Calculation around a Base Station Antenna

2007 ◽  
Vol 3 (2) ◽  
pp. 115
Author(s):  
Antonio Šarolić ◽  
Borivoj Modlic
Keyword(s):  
Hazard Analysis ◽  
Near Field ◽  
Three Dimensional ◽  
Real Life ◽  
Base Station ◽  
Radiation Hazard ◽  
Specific Situation ◽  
Field Calculation ◽  
Single Antenna ◽  
Level Calculation

In the near field, the antenna pattern provided by the antenna manufacturer is generally not applicable, or shouldbe considered with caution, even for the single antenna in free space. In the real life, antenna is often surrounded by other conductive objects in the immediate vicinity. These objects tend to distort the antenna radiation pattern. Since the electromagnetic field calculation for the coverage or radiation hazard analysis depends on the three-dimensional antenna gain, this effect should be taken into account. This paper suggests the use of "installation uncertainty" that should be added to the field calculation. The amount of this quantity depends on the installation geometry and can be calculated numerically for a specific situation. This paper shows the results of numerical calculations for some typical antenna installation geometries.

scholarly journals Brown Coal in Victoria, Australia and Maddingley Brown Coal Open Cut Mine Batter Stability

2020 ◽  
Vol 9 (3) ◽  
pp. 109-118
Author(s):  
Lei Zhao ◽  
Greg You
Keyword(s):  
Coal Seam ◽  
Brown Coal ◽  
Large Scale ◽  
Low Cost ◽  
Three Dimensional ◽  
Open Pit ◽  
Open Pit Mining ◽  
Mining Operations ◽  
Power Generators ◽  
Three Dimensional Finite Element

Brown coal is young, shallowly deposited, and widely distributed in the world. It is a fuel commonly used to generate electricity. This paper first reviews the resources and characteristics of brown coal in Victoria, Australia, and its exploitation and contribution to the economy or power supply in Victoria. Due to the shallow depth of the brown coal seam, e.g. very favorable stripping ratio, open pit mining is the only mining method used to extract the coal at low cost for power generators. With the large-scale mining operations, cases of batter failure were not rare in the area. From the comprehensive review of past failures, overburden batter tends to fail by circular sliding, coal batter tends to fail by block sliding after the overburden is stripped due to a weak water-bearing layer underneath the coal seam and tension cracks developed at the rear of the batter, and batter failure is typically coincided with peak raining seasons. Secondly, the paper reviews the case study of Maddingley Brown Coal (MBC) Open Cut Mine batter stability, including geology, hydrogeology, and hydro-mechanically coupled numerical modelling. The modelling employs three-dimensional finite element method to simulate the MBC northern batter where cracks were observed in November 2013. The comprehensive simulation covers an overburden batter, a brown coal batter, two rainfall models, and a buttressed batter. The simulated results agree well with observed data, and it is found that the rainfall at the intensity of 21mm substantially lowered the factor of safety of the coal batter.

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