Dwayne D. Tannant

Guidelines for Mine Haul Road Design

Preface The idea of developing a haul road manual or collection of guidelines was initiated by the late Professor Muirhead at the University of Alberta in 1999. Support and financial contributions for this work were obtained from NSERC, SMART (Surface Mining Association for Research and Technology) ATCO Power, and Finning. Both Syncrude Canada Ltd. and Suncor Ltd. provided access to road design data and methodologies. Syncrude Canada Ltd.s internal reports were instrumental in verifying the strain-based design approach for haul roads that is advocated in this manual. Two closely related documents form a basis for this manual. The oldest is the report by Kaufman and Ault (1977) entitled Design of Surface Mining Haulage. Monenco (1989) took the Kaufman and Ault report and updated it to reflect conditions relevant to Canadian mines. The Monenco report is unpublished and difficult to obtain. The questionnaire survey that is found in the Monenco report was repeated in 1999 for this document. Content from the M.Sc. thesis by Kumar (2000) is also used in this document, especially in sections dealing with design of a haul road cross-section. Bruce Regensburg put together the section on haul road economics. In addition, haul road design issues were also gathered from various published sources that are referenced in these Guidelines for Mine Haul Road Design.

Rockbolt behaviour under dynamic loading: field tests and modelling

Abstract Knowledge of rockbolt response under dynamic loading conditions is important when rockbolts are used to support ground subjected loads from blasts, earthquakes or rockbursts. Dynamic strain measurements from strain gauges mounted on end-anchored rockbolts and velocity measurements from geophones mounted on the rock surface were recorded during two different blasts. These blasts caused peak particle velocities in the rock exceeding 1 m/sec but maximum dynamic stresses in the bolts were well below the yield point of the steel. The measurements were analysed by analytical methods and a numerical model which was developed to explain the measured rockbolt variations resulting from the dynamic loading caused by the blasts. The numerical model developed for this study is a one-dimensional finite difference representation of a mechanical system involving the following components: the wave source, the rockmass, the mechanical rockbolt, and the anchor and head connections. The measured strains on the rockbolts and the dynamic movement of the rock surface were closely simulated by the numerical model. Both axial and lateral free vibrations were excited in the rockbolts by the dynamic loading and the vibrations persisted much longer than the ground motions. Damping at the connections between the rockbolt and the rockmass at the anchor and the plate influence the transfer of the stress wave from the rock to the bolt and the resulting frequency of vibrations in the rockbolt.

Discrete element method contact model for dynamic simulation of inelastic rock impact

A contact model for inelastic impact-rebound events such as those that occur when a rock bounces down a slope is developed for dynamic simulations using the discrete element method. Upon impact, the normal contact force follows a linear elastic relationship as a function of relative displacement up to a pre-set transition force, after which the contact force is fixed at the transition force until the relative velocity between the objects in contact reaches zero. Upon unloading (rebound), the contact force follows a power function that enables the contact model to remove, in a time-stepping manner, significant stored elastic energy from the contact thus reducing the rocks kinetic energy. The model automatically generates lower values of coefficient of normal restitution as the impact velocity increases.

Properties of fly ash stabilized haul road construction materials

ABSTRACT Larger haul trucks are being used at surface mines in Canada thus requiring better haul roads to carry heavier loads. The availability of good quality aggregate to build haul roads is limited for prairie coal mines. However, most of these mines are located adjacent to coal-fired electrical power plants, which produce by-product fly ash as a waste. Fly ash can be used to increase strength and stiffness of soil and road bases. Unconfined compressive strength tests conducted on various mixtures of fly ash, kiln dust, mine spoil, and coal seam partings showed that the cementing characteristics of unclassified fly ash from central Alberta coals was low. However, the addition of cement kiln dust, which is high in CaO, enabled the fly ash to exhibit significant cementing action. Mixtures of fly ash, kiln dust, and mine spoil or coal seam partings had unconfined compressive strengths of about 1 MPa and elastic moduli of about 350 MPa after 14 to 28 days. This compares favourably with compacted mine spoil or coal seam partings which have estimated unconfined compressive strengths of less than 0.4 MPa and moduli of about 50 MPa. Thus fly ash stabilized mine spoil or coal seam partings were found to have potential for use in constructing haul road base and sub-base layers since maximum tire pressures on the running surface are less than 0.7 MPa.

Determination of fault-related sloughage in open stopes

Abstract Open stope mining is a common bulk mining method that is often affected by fault-related dilution where dominant geological weaknesses or faults exist. Invariably, most metalliferous orebodies extracted by open stope mining are associated with faults by their mode of genesis. Hence, a better understanding of the manner by which faults increase the risk for sloughage and a method to estimate the extent of sloughage in stopes near a fault are required. Elastic–plastic finite element stress models were used to show that faults increase the size of the relaxed zone in stope walls and that this relaxation increases the risk of sloughage. A criterion for fault-related sloughage, defined as the stress level below which rock blocks unravel, is established and a procedure is presented for estimating the size and shape of the fault-enhanced relaxed zone for any given set of ground conditions and stope geometry. The equivalent linear overbreak/slough, ELOS, concept is used to quantify the dilution. The procedure is applicable to blocky and moderately jointed rock masses, and 2D or 3D numerical codes can be used. Knowledge of the extent of potential sloughage helps in support design as it provides an estimate of support demand and cablebolt length. Two case histories are presented to illustrate the procedure.

Operator and dipper tooth influence on electric shovel performance during oil sands mining

A shovel performance monitoring study was undertaken in two oil sands mines operated by Syncrude Canada Ltd. using performance data obtained from P&H 4100 TS and BOSS electric mining shovels. One year of shovel performance data along with geological, geotechnical and climatic data were analysed. The approach adopted was to use current and voltage data collected from hoist and crowd motors to first identify dig cycles and then to calculate the energy and/or power associated with digging. Analysis of performance data while digging uniform material along with operator team schedules showed that the performance of a shovel can vary significantly depending on which operator is digging. Up to 25% variability in hoist power consumption and 50% variability in productivity was noted between different operators. Shovel type and dipper teeth configuration can also influence the power draw on electrical motors during digging.

Thin tunnel liners modelled with particle flow code

Simple discrete element models using PFC2D models with bonded assemblies of particles were used to numerically simulate direct tension and block punching tests on thin spray‐on tunnel liner materials to gain insight about the liner support mechanisms. PFC2D input parameters were calibrated such that the rupture load and elongation at rupture were similar to the laboratory test data. The calibrated model of the liner material was then used to simulate a liner around a highly stressed tunnel in rock where stresses caused extensive fracturing near the top of the tunnel. The effect of the liner was analysed by modelling the tunnel with and without the liner and showed that the liner had minimal impact on fracture propagation in the rock because of the liners highly deformable nature. However, the liner was able to retain the fractured rock in place.

Thin Rock Support Liners Modeled with Particle Flow Code

Rapid setting, thin, spray-on polymeric liner materials are being developed for underground rock support in Canadian mines (Tannant, 2001). These materials have performance characteristics that lie between those of shotcrete and mesh. Twodimensional numerical models using Particle Flow Code (PFC) (Itasca, 1999) are used to model thin spray-on liners in simulated laboratory tests. The objectives were to determine how to model liners with PFC and based on these results to gain some insight about the support mechanisms provided by a liner. Direct tension tests and block punching tests were numerically simulated and used to calibrate the PFC micro-mechanical input parameters. Based on previous laboratory testing, the representative properties for a generic liner material are a tensile strength of 2MPa achieved at 50% elongation (Tannant, 2001). The tensile strength is equivalent to a rupture load of 2kN per millimeter of liner per linear meter. A typical thin spray-on liner thickness used to support rock around an excavation is about 4ram. Therefore, the PFC liner models were calibrated to break at around 8kN per linear meter of liner material.

Performance monitoring of electric cable shovels

A shovel performance monitoring study at an oil sands mine used current and voltage data from hoist, crowd and swing motors of P&H 4100 series electric cable shovels. The goal was to identify key shovel performance indicators using only data from the motors. It was found that hoist and crowd motor responses can be used to identify different shovel activities, especially the dig cycle. Some key shovel performance indicators examined are the dig cycle time, digging energy and digging power. By averaging the hoist power over a number of dig cycles, the average hoist power is less sensitive to digging trajectory and could be a useful parameter for assessing ground diggability characteristics. Analysis of performance indicators showed that the shovel performance can be significantly influenced by the operator. The study revealed that freezing temperatures can have a minor and localized influence on shovel performance.

UAV: Low-cost remote sensing for high-resolution investigation of landslides

The civilian use of small inexpensive mini- and micro-UAVs has increased dramatically in the past few years. UAVs can be used for natural hazards management. In this context, UAVs can be very useful for surveying and monitoring of active small landslides in urban environments. In this paper, a methodology for the data acquisition and processing that considers the landslide typology is presented and discussed. Two case studies from the northwest part of Italy are also described to illustrate the presented methodology.