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By Padmavathi V, M. Najamuddin, M. R. Madhav

Granular piles are one of the leading ground improvement techniques, adopted for the betterment of bearing capacity and reduction in settlements of the foundations and also to accelerate consolidation of the surrounding soil. In the recent past, there has been extensive research on the settlement analysis and behavior of granular piles under varied soil conditions. The application of these theoretical solutions to practical problems requires a knowledge of representative values of the deformation parameters of the ground and the granular piles. However, very little information is available on these parameters. The paper presents a new method for the estimation of the modular ratio of granular piles and modulus of deformation of the surrounding in-situ soil from the compression load tests. The load - settlement response obtained from the compression test results are used in the back analysis for estimating the modulus of deformation of the ground. The presence of granular bed, under the rigid plate for load testing, has been given due consideration in quantifying the proportion of load transferred on to the stone column. Based on these considerations a new method is developed to estimate the modulus of deformation of the ground and the modular ratio of the granular pile.

Sep 1, 2022

By Chu E. Ho

This paper reviews the design of jet grouting at re-entrant corners of excavations where the diaphragm wall and secant pile wall installation were interrupted by existing utilities in the streel sidewalk. Jet grout blocks were formed to seal the gaps in the walls for excavation support, consisting of four to six columns in clusters. Jet grouting was performed around an electrical duct bank which had to be maintained. Jet grouting was executed through stratified soils using various combinations of jetting parameters for different soil strata. The installation sequence and age of the neighboring columns within a cluster will affect the jet’s ability to form subsequent columns. When jet cutting is limited next to hardened grout columns or embedded obstructions (such as diaphragm walls or secant pile walls in this case), the specific gravity (SG) of spoils would be reduced and tend toward the value of the injected grout SG. The magnitude of spoil SG is also influenced by the variability of the grout mix supplied. Specific Gravity Ratio (SGR) defined as the ratio of spoil SG to the actual grout SG at the time of jetting can be used as an indicator of successful treatment, with SGR > 1.0 indicating effective soil erosion. Verification coring and testing were implemented to confirm target column diameter and strength of grouted soils have been achieved.

May 1, 2022

By Sanjay Gupta, Sorabh Gupta, Ravi Sundaram

A geotechnical forensic evaluation of piles for an industrial facility in Haryana was performed to assess the quality of the piles and to evaluate piles installed using two different types of rigs. Low strain pile integrity tests were performed on all piles to assess the pile length and possible presence of structural defects. Coring was done through questionable piles for the clinching evidence of concrete quality and pile length. Probe holes adjoining piles helped confirm the bulging of piles at shallow depth. The paper highlights the importance of implementing a well-planned quality assurance program to confirm that all piles installed are of the desired quality.

Sep 1, 2022

By Gust Van Lysebetten, Monika de Vos

The objectives of monitoring geotechnical structures can be very diverse, including optimisation of the design, quality control, long term performance assessment, and approval of innovative execution techniques. In this context, new measurement techniques, based on optical fibres, offer the possibility of accurate strain and temperature monitoring with very small sensors and limited numbers of cables. This paper briefly presents optical fibre sensing techniques and illustrates their application to geotechnical structures by means of some projects, carried out by the Belgian Building Research Institute (BBRI).

May 1, 2022

By Dr Karsten Galipp, Kai-Julian I. Hendler, Prof. Manuel G. Pinheiro, Dr Peter J. Bourne-Webb

With a share of approximately 11% of global greenhouse gas emissions, the construction industry contributes significantly towards climate change. This is why construction projects should not only be assessed on costs and technical solutions, but also on their carbon emissions. Life Cycle Assessment (LCA) is a tool which can quantify the environmental impacts of a construction project over its entire lifetime. The objective of this study was to determine the carbon footprint of three types of quay wall structures, namely sheet pile combi-walls, open piled decks and caissons using an LCA approach. Each of these quay walls were studied under the same boundary conditions, such as design life, ground conditions, dimensions, location and so on. The analysis showed that the sheet pile wall has the lowest carbon footprint whereas the open piled structure has the highest. Furthermore, it could be shown that the largest share of greenhouse gases (approximately 80%) is emitted during the production of construction materials. The transportation of materials and construction activities each contributed under 12% to total emissions. The sensitivity analysis showed that with innovative approaches, such as adapting the concrete mix design, the carbon footprint could be reduced by 26% to 40%.

May 1, 2022

By Alexander Blatt, Franz-Werner Gerressen

Diaphragm walls are known as underground structural elements commonly used as retention systems for excavation pits and shafts and permanent foundation walls or elements. One can anticipate that global urbanization and increasing demands on environmental considerations will need to be accommodated in underground space in the future. These trends show an increasing requirement for diaphragm walling in even more complex conditions, especially in inner-city applications with limited space. Complex conditions in terms of space limitations, especially for inner city job sites, require specifically adapted solutions for slurry, spoil, reinforcement and concrete handling and the related logistics to ensure smooth production. Furthermore, one focus will be given to the QA/QC topics of the production process. Real time installation control, data transfer and reporting systems become more and more important. Therefore, the paper will describe the construction method and the sequence of activities required for the construction of diaphragm wall systems. It will describe also the main equipment that will be needed to execute these works under various conditions. In addition to the general description of the system and the required equipment, the paper will show some site examples for infrastructure projects with their specific solutions when working under space restrictions.

Nov 1, 2022

By Chandramohan P. V

A unique tension pile where the pull is at a point a certain distance below the top of the pile. The pull is transferred by a cable consisting of high tensile strands. The HDPE duct of the cable prevents bond between the strands and pile concrete in upper portion. While soil friction on the pile will act downwards on the whole length, there is tension in the bottom portion of pile, there will be compression at the top portion.

Nov 1, 2022

By Racquel Nottingham, Marc Mastrantuono

Micropiles often provide a favourable solution for many deep foundation problems especially when significant site constraints such as confined construction sites or vibration limitations have been identified. Often the durability of buried steel elements are heavily scrutinized in order to effectively determine the rates of corrosion and methods to reduce this while still maintaining the structural integrity of the engineered solution. Practices such as sacrificial corrosion loss and the introduction of plastic sheaths have become the go-to methods of corrosion protection. Since the introduction of the micropile, other solutions have been developed, namely protection with an adequate grout encapsulation. This paper will explore corrosion protection of micropiles and the guidelines provided in the published codes and norms. Since few codes define the exact way to verify the durability of these micropiled structures, the existing data is presented and the analysis of grout encapsulation as an effective corrosion protection method is evaluated.

Oct 1, 2022

By Marcus Daubner

This paper explains how BAUER Spezialtiefbau GmbH uses digital methods on projects - starting from work preparation to completion of works. More precisely, the advantages of BIM-based planning during work preparation and the automated and structured data management - both machine production data and the manually recorded quality-relevant reports - during execution phase are displayed. In this context, the benefit of the digital twin to optimize processes, to reduce defect costs, for a more effective reporting sys-tem, and the further usage of as-built information in the BIM or GIS process is described.

Sep 1, 2022

By J. C. Cawley, G. T. Homce

The U.S. National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) conducted a study of mining industry electrical injuries reported to the U.S. Mine Safety and Health Administration (MSHA) for the years 2000 to 2009. The findings of that study are detailed in this paper, and serve to characterize the circumstances surrounding electrical injuries and identify causal factors. The study included three tasks: 1) a direct review of mining industry occupational injury data compiled by MSHA, 2) interpretation of the narrative descriptions available for the injuries (from MSHA data) and 3) a separate examination of fatal electrical injuries. Eight-hundred sixty-five electrical injuries were reported during the 10-year period studied, with 39 of those being fatalities. This makes electrical injuries disproportionately fatal with respect to most other types of injuries in mining. Electrical injury rates were higher in coal mining than noncoal mining and, within the coal sector, rates were higher in underground operations than in surface operations. Of the 865 total cases, electrical and machine maintenance or repair activities were involved in 580 (69%), and electricians and mechanics were injured in 362 cases (42%). Of the 39 fatal electrical injuries, 27 (69%) involved electrical maintenance or repair work, and in 21 of these 27 cases, the failure to de-energize, lock-out and tag the circuit was the cause or a contributing factor. Also, contractor employees had a much greater chance of an electrical injury being fatal than did mine operator employees. The top three root causes for fatal electrical injuries were 1) no or inadequate lock-out and tagging, 2) failure of power system components and 3) contact of overhead electrical power lines by mobile equipment.

Jan 1, 2013

By R. Krog, M. Valente, R. Ochsner, W. Marchewka, R. Jensen, R. K. Zipf

A tube bundle system (TBS) is a mechanical system for continuously drawing gas samples through tubes from multiple monitoring points located in an underground coal mine for analysis and display on the surface. The U.S. National Institute for Occupational Safety and Health (NIOSH), in collaboration with Signal Peak Energy (SPE), LLC, Bull Mountains No. 1 Mine, operated a TBS during mining of two bleederless, longwall panels. This paper describes the gas analysis data and its interpretation. As verified by the TBS, coal at the SPE mine tends to oxidize slowly. It was known that a reservoir of low-oxygen concentration atmosphere developed about 610 m (2,000 ft) behind the longwall face. A bleederless ventilation system facilitates formation of an inert atmosphere in this longwall gob and decreases the likelihood of spontaneous combustion. Connections of the mine atmosphere to the surface through subsidence cracks could allow airflow into the longwall gob, revive coal oxidation and increase spontaneous combustion risk. The atmospheric composition of the sealed areas was homogeneous, except in the immediate vicinity of suspected ingassing points. The TBS verified that gases within the partially sealed, bleederless longwall gob expanded into the longwall tailgate area when barometric pressure decreased. The concentration of carbon dioxide in the back return airflow at the longwall tailgate was observed to increase by a factor of three and possibly up to 10 times the typical background concentration of 0.5 to 1.0%, depending on the size of the longwall gob and the magnitude of barometric pressure decrease. TBS have the inherent disadvantage of slow response time due to travel time of the gas samples and sequential gas analyses. A TBS or similar continuous monitoring system could be beneficial in detecting and providing warning of potentially hazardous gas concentrations, if the slow response time of the system is always understood.

Jan 1, 2013

By M. K. Larson, J. K. Whyatt

Proper employment of numerical stress analysis design tools is based on the demonstrated ability of a model to capture key elements of the geologic site model and accurately simulate how these elements interact with a mine design. While these tools have progressed markedly, they are, at heart, a gross simplification of the abundant complexity of a natural setting and its response to mining. A generic deep longwall site model was developed that includes aspects of the geology of deep coal mines in the Wasatch Plateau and Book Cliffs coal fields of Utah. The site model contains a set of common features and observations of how these features typically respond to mining. This site model was the basis for evaluating use of empirical, boundary element and volume element stress analysis tools to analyze the distribution of stress around a deep longwall panel. More specifically, this evaluation examined shifting of stress to panel abutments and gob, distribution of stress in the abutment and deformation and failure of bridging strata. Measurements of abutment stress changes at two sites in the Wasatch Plateau region were used to illustrate model calibration. Overall, these comparisons highlight the considerable differences between methods. Volume element tools can incorporate considerable detail and have fewer underlying assumptions, but this detail carries a considerable computational cost. Boundary element tools are much more efficient. However, this efficiency comes at the cost of added assumptions. These assumptions were challenged by the presence of a strong sandstone unit in the overburden, leading to boundary element results that depart significantly from volume element results. Empirical rules are the simplest, but are even more burdened by assumptions, many of which are implicit in underlying cases. Insight into the nature and impact of underlying assumptions in each method is essential to the proper use of results in mine design.

Jan 1, 2009

By W. Collingwood, K. V. Raj, S. Bandopadhyay

In the mining industry, computational fluid dynamics (CFD) modeling is used extensively to simulate air flow in underground mines. CFD modeling of pollutant transport in openpit mines is relatively new. Modeling the actual pit geometry of an openpit mine and the open domain is complex. The complexity is primarily due to the faceted geometry of an openpit mine with its numerous associated sharp features. Important issues that are not considered carefully at the geometry level are generally propagated to the subsequent processes. Several challenges and pitfalls are encountered in modeling pollutant transport in openpit mines. These challenges and pitfalls are related to the geometry, meshing, boundary conditions and turbulence modeling parameterization. An appropriate mesh selection is critical. A detailed discussion of the meshing of the domain of an openpit mine is presented in this paper. The selection of an appropriate turbulence model, such as kappa-epsilon (κ-ε), large eddy simulation (LES), Reynolds stress model (RSM), etc., to obtain the best possible solution is equally significant. This paper discusses the various challenges in modeling the pollutant transport process in an openpit and some of the approaches adopted to address these challenges.

Jan 1, 2013

By S. Frimpong, G. Galecki

Dump truck tires are often used in long-haul roads in rugged terrain, with high rolling and grade resistances. These conditions increase the ton-kilometer-per-hour (tkm/hr) or short-ton-mile-per-hour (stmph)rating of tires, leading to tread wear, cuts and complete failures. The load-bearing capacities of these tires are sometimes exceeded, with truck overloading, overstressing, heating and subsequent failures. In addition, truck tire demand far exceeds the current supply capacity, with long lead ordering time. This condition has caused severe tire shortage, and the problem is expected to be sustained in the long-term. Industry has taken extensive practical measures to prolong tire service life with significant results. However, this problem can be solved through fundamental and applied research initiatives. This paper pioneers a research effort in tire service life using multibody physics, fatigue failure modes and soil failure dynamics to develop tire-road contact force dynamics. A virtual prototype simulator of the tire-road contact, using the CAT 775E (with standard tire 24.00R35) was developed and simulated within the MSC.ADAMS/NASTRAN environments. The results show the areas of the loaded tires with maximum Von Mises, principal and shear stresses, which could result in fatigue failure, tire wear and tear and blowouts. The maximum Von Mises stresses on the six truck tires are between 35 and 58 MPa. The maximum shear stresses are also between 19 and 33 MPa. These stresses will cause early tire failures given an average operating schedule of between 20 and 24 hours per day. The isolated areas with maximum stresses will be subjected to further studies to reduce stress intensity while preserving tire performance.

Jan 1, 2012

By T. J. Lutz, S. Gallagher, J. R. Srednicki, J. J. Sammarco

The Illuminating Engineering Society of North America reports that an underground mine is the most difficult environment to illuminate (Rea, 2000). Researchers at the U.S. National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) are conducting ongoing studies designed to explore different lighting technologies for improving mine safety. Underground miners use different visual cues to escape from a smoke-filled environment. Primary and secondary escapeways are marked with reflective ceiling tags of various colors. Miners also look for mine rail tracks. The main objective of this paper is to compare different lighting types and ceiling tag colors to differentiate what works best in a smoke-filled environment. Various cap lamps (LED and incandescent) and lasers (red, blue, green) were compared to see which options resulted in the longest detection distances for red, green and blue reflective markers and a section of mine rail track. All targets advanced toward the human subject inside of a smoke-filled room to simulate the subject walking in a mine environment. Detection distances were recorded and analyzed to find the best cap lamp, laser color and target color in a smoke environment. Results show that cap lamp, laser color and target color do make a difference in detection distances and are perceived differently based on subject age. Cap lamps were superior to lasers in all circumstances of ceiling tag detection, with the exception of the green laser. The incandescent cap lamp worked best in the simulated smoke compared to the LED cap lamps. The green laser was the best color for detecting the tags and track compared to the red and blue lasers. The green tags were the easiest color to detect on the ceiling. On average, the track was easier for the subjects to detect than the ceiling tags.

Jan 1, 2013

By C. D. Litton

When methods to prevent the occurrence of fire in underground mines fail, the next line of defense is to rapidly and reliably detect the developing fire, so that subsequent evacuation and control procedures can be safely and successfully implemented. To provide this capability requires an understanding of the operational principles of different types of fire sensors, their merits as well as their limitations, and performance characteristics of the monitoring systems that control and process sensor data; an understanding of how fires develop and the different types of fires that can occur, along with their characteristics and the hazards they present; an understanding of the impact of the mine environment and routine mining activities, not only in terms of these effects on fire sensors but also in terms of the impact of mine ventilation and mine geometry on fire growth, fire characteristics and the detection process. All of these factors are components of the technology of fire detection, and when insufficient knowledge of any of these components exists, the ability to implement adequate mine fire detection systems is diminished. Within the last decade, significant advances have been made in fire detection technology applicable to underground mines. These advances include not only the development of improved sensors and better monitoring systems, but also an expanded understanding of how to deploy sensors, set sensor alert/alarm levels, account for ventilation effects, etc. In addition, there has been an increase in our knowledge of the types of fires that occur, the types of combustibles involved, characteristic times for fire growth and development, the levels of heat, smoke and gas that are produced and the hazards that result. It is the intent of this paper to provide not an overview of current mine fire detection technology and, also, to present data obtained for some smoke sensors that have potential for use in underground mines. The paper will also discuss the data, information and resources that are currently available and seek to identify those areas most in need of further research and development.

Jan 1, 2011

By C. V. Deutsch, J. B. Boisvert, J. L. Deutsch

Data used to build geostatistical models come from a wide variety of sources with potentially differing sample errors and volume supports. Typically all available sample measurements are pooled together for statistical analysis irrespective of the quality of the data. The sample data is used to assess spatial continuity, make local estimates and assess uncertainty. A new methodology is proposed to simplify accounting for samples of differing quality. The result is improved estimates with higher weights assigned to high-quality samples, while low-quality samples receive less influence in resource estimation. A new dimension, d, is introduced and calibrated to account for sample error and/or volume during estimation. The addition of an extra dimension can be easily incorporated in existing kriging or inverse distance workflows. The only additional parameters required are the sample error and volume for each datum. The methodology is demonstrated and the improvement in local accuracy is documented. Extending the dimensionality of the domain to four (three spatial dimensions and the additional d dimension) requires a valid 4D variogram model; therefore, the spherical variogram model is generalized to arbitrary n-dimensions.

Jan 1, 2011

By S. A. Smith-Hamm, E. A. Sarver, A. S. Cox

Appalachia is an increasing concern, as unnaturally high TDS and/or associated specific conductivity (SC) may contribute to deteriorated stream ecosystem health. The aim of this preliminary study was to explore the efficacy of accelerated leaching as a means of minimizing long-term TDS/SC generation by problematic overburden materials. Five spoil samples were collected and leached using simulated rainwater solutions under ambient and acidified pH conditions. SC and pH were monitored during each leach cycle, and inductively coupled plasma-mass spectroscopy (ICP-MS) was used to determine how leaching conditions affected the release of specific ions. This paper highlights the results of both jar and column leaching tests. Among the most significant findings was that for certain spoil materials, the SC in the leach column effluent was effectively reduced when the spoil was first leached with acidic rainwater followed by ambient rainwater, as opposed to leaching with ambient rainwater alone. This suggests that accelerated leaching might aid in the long-term stabilization of some materials.

Jan 1, 2015

By J. D. Noll, J. A. Organiscak, A. B. Cecala

Over the past decade, a substantial effort has been made to improve the air quality inside enclosed cabs of both underground and surface mobile mining equipment to reduce respirable dust exposures by the equipment operators. As part of this effort, the U.S. National Institute for Occupational Safety and Health, (NIOSH) completed a comprehensive laboratory study that determined the significant factors for cab filtration and pressurization systems. From this information, a major underground mining equipment manufacturer designed a filtration and pressurization system that was incorporated into the enclosed cabs of its equipment. A long-term evaluation was performed on the effectiveness of this filtration and pressurization system to improve the air quality in the enclosed cabs of two different pieces of equipment, a face drill and a roof-bolter machine, at an underground limestone mine. This long-term evaluation demonstrated a significant reduction in dust levels between outside-to-inside cab respirable dust concentrations. During this evaluation, a modification to remove one of the filters on the roof-bolter machine simplified the design without sacrificing the system’s efficiency. Tests using particle count instruments performed during nonproduction time periods on both pieces of equipment indicated protection factors greater than 100 when comparing respirable-sized dust particles inside the enclosed cab relative to outside.

Jan 1, 2012

By R. V. Ramani, K. V. Raj, S. Bandopadhyay

The air flow problems in openpit mines are complex. Computational fluid dynamics (CFD) models can provide detailed information regarding air flow pattern, velocity distribution, temperature, and pollutant concentration in an enclosed domain of an openpit mine. A range of turbulent models can be selected with varying complexity and accuracy. Pollutant transport models, however, differ in their assumptions and structure as well as in the algorithms they use. As a result, predictions vary from model to model. This paper presents a study of pollutant transport in an actual openpit mine under a stable boundary layer. The objective was to test two turbulence models using similar geometry and the same input conditions and model constants. Measured data were used to compare the results of the two CFD models, namely, the kappa-epsilon (к-є) model and the Large Eddy Simulation model. Despite the complex synoptic situations, different meteorological input data and fast-changing conditions, the simulation results from both the models were in good agreement regarding the dispersion of pollutants.

Jan 1, 2015