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By Muhammad Zaka Emad

ABSTRACT: Sublevel stoping mining methods with delayed backfill employs cemented rockfill (CRF) as a backfill material. It is used in underground mines to achieve ground control and reduce wall slough. In addition CRF serves to reduce development waste and provides a working surface for mining the upper levels. Efforts to optimize CRF practices have been published. This paper presents a detailed review of CRF practices in open stoping mining systems with reference to case studies. A new methodology is suggested in a simple stepwise approach, which can be adopted for site specific conditions. The need of laboratory testing and quality control program is discussed based on the published literature.

May 1, 2013

By Kazem Oraee, Mehran Gholincjad, Navid Hosseini

"Chain coal pillars are pans of the structure of longwall mining system that play a significant role in the stability of the entries. With mechanization and developments in the various aspects of the method, higher efficiency in optimization of the design of chain coal pillars seems appropriate. In this paper the three main methods of chain pillar design, namely the empirical analytical and numerical methods arc compared. Real data from the Tabaslran coal mines have been used in order to make the comparison process reliable. It is concluded that the most apparent advantage of the empirical method is the reliability of the results while the use of numerical methods enjoys the advantage of flexibility. On the other hand the analytical methods are complex unless simplifying assumptions arc made that can substantially decrease the accuracy of result which is thought to be the main advantage of the design method. A new method is therefore introduced here that combines all of the three presently used methods and by doing so the new method has the advantages of the three while minimizing complexities and inaccuracies associated with the use of the individual methods.INTRODUCTIONLongwall mining is a high production method that can use mechanization to its full extent. Its initial development can be traced to 17th century European collieries but it was not until the second half of the 20th century with the development of self advancing support systems that the method gained popularity in the USA (Oraec. 2001). During the last decade, the production of longwall faces has increased significantly (Peng. 2006). The ability for mechanization along with good safety condition is the main reasons for such development. In the longwall mining method a good design for panel and entries on both sides, are two essential parameters. In this method, the thickness of overburden (depth of mine) nom1ally ranges from 60 to 20 m (197 to 2.7 9 ft) (Hartman, 2000) and with increasing mine depth designing for stabilizing the entries on both sides of the panel become more difficult. Thus, for safety and stability the size of chain pillar must increase. This causes the overall coal recovery to decrease and increase mining costs per ton. As such wide pillars hinder the air flow and hence ventilation costs increases too. Therefore with accurate identification of loading conditions and stress analysis. pillar that are a minimum size and sufficient safety factor are carefully designed."

Jan 1, 2010

By F. Ntuli, T. V. Nyangadzayi

Chromium green is an essential metal with various applications in the paints, construction, electronics, and aerospace industries. The main source of chromium green is the carbo-thermic reduction of chromite ores, however, chromite ores are being heavily depleted on a global scale, hence the need to find alternative or secondary sources for the chromium. In order to meet the global demand for chromium there is a need to implement principles of the sustainable circular economy to keep chromium within the material loop. Ferrochrome slag and stainless steel slags are secondary resources that are potential sources of chromium. In this work, recovery of chromium from ferrochrome slag was investigated. The ferrochrome slag was alkaline leached using sodium hydroxide- sodium hypochlorite solution to reduce the use of potent reagents that have a potential negative environmental impact. The leachate produced by oxidative alkaline leaching of ferrochrome slag contained hexavalent chromium, which was used to recover the extracted chromium through a two-stage process involving reduction and precipitation. Reduction of hexavalent Cr to trivalent Cr was investigated using anhydrous FeSO4 at concentrations of 5 g/L, 10 g/L, and 15 g/L. Precipitation was conducted by dosing the reduced leach solution with 1 M sodium hydroxide at dosages of 5 ml/L, 10 ml/L, and 15 ml/L. The experiments were designed using the Taguchi (L9) orthogonal array and analysed according to the ANOVA, general linear model. The optimized conditions for the reduction step were ferrous sulfate dosage of 5 g/L with a pH of 12, and for the precipitation step, 1 M sodium hydroxide at a dosage of 15 ml/L with a setting time of 90 minutes and pH of 7. Physical changes were observed during the two-step chromium recovery, with solution changing from a yellowish colour to dark green colour indicating completion of the reaction. The chromium recovery was found to be 93.3%.

Dec 11, 2024

By L. X. Li

Coking coal producers often encounter variations in clean coal quality when mining multiseam deposits containing coals with different washability and coking properties. This paper describes how, for a single coal property, an initial clean coal specification with an ash content of 8.5% on an air-dried basis (ADB) and a free swelling index (FSI) of 5.5 can be improved to a specification with 7.5% ash content ADB and an FSI of 6. This is accomplished by sorting coal seams into two groups for processing and blending. A preliminary economic model demonstrates how this improvement enhances economic returns through a beneficial factor.

Jan 1, 2014

By A. M. Bryukhanov, A. G. Mnukhin

The report states accident rates for gassy/dusty coal mines represented as an ergatic system "man – machine - environment" with further analysis by the method of conditional probabilities. A coal mine has been analyzed with allowance for the attending personnel, equipment and environment as a sequence of events and states. Probabilities of operational states have been determined and prediction of mine behavior has been made on the basis of investigation findings for equipment and the personnel states, and analysis of the environment (i.e. mine and mining conditions). Utilization of expert estimation methods has been considered for determining major operational parameters of gassy/dusty mines. The importance of standardized values of permissible occupational risks (permissible probability of accident, PA) is demonstrated. It is also stated that a procedure is essential to determine these values, involving regular check-ups of the integral safety criterion at all mines and further development of customized recommendations for individual mines on efficient improvement of accident situations. Methodology to determine the assessment criteria has been developed and scientifically substantiated for permissible accident rates in hazardous industries.

Jan 1, 2003

By G Luxbacher

Computer simulation of mine ventilation systems is rapidly becoming an essential tool in mine planning and design. This paper examines the utilization of ventilation simulation techniques to evaluate the number, shape, size and layout of mine entries in a typical coal mining system. Since the mains and sub-mains serve mainly for transportation and ventilation and the ventilation system is critically important to the health and safety of the workers, there exists a great need for optimal designs in this area. Evaluation criteria, could include, among others, minimization of power costs, shaft requirements and leakage. Constraints of this optimization problem include health and safety regulations and production and mine infrastructure requirements.

Jan 1, 1977

By R. V. Ramani, G. W. Luxbacher

Computer simulation of mine ventilation system is rapidly becoming an essential tool in mine planning and design. This Paper examines the utilization of ventilation simulation techniques to evaluate the number, shape, size and layout of mine entries in a typical coal mining system. Since the mains and sub-mains serve primarily for transportation and ventilation and the ventilation system is critically important to the health and safety of the workers, there exists a great need for optimal designs in this area. Evaluation criteria could include, among others, minimization of power costs, shaft requirements and leakage. Constraints of this optimization problem include health and safety regulations and production and mine infrastructure requirements.

Jan 1, 1980

By Niloy K. Nath

Two layer sintering by charging green sinter mix with normal coke rate in the upper layer and reduced coke rate in the lower layer, can substantially reduce the coke rate and also improve the sinter quality by producing more uniform thermal profile through out the bed height. The two-layer sintering process have been analyzed by numerical simulation of the process by a detailed CFD based model, considering all the important phenomena like gas-solid reaction, melting and solidification, flow through porous bed, heat and mass transfer etc. Optimization techniques like genetic algorithm, differential evolution is then applied to evaluate the optimum coke rate in the two layers of the bed to produce the ideal thermal profile and melting fraction in the sinter bed for optimum sinter quality. Through this optimization method both high quality sinter with minimum return fines can be achieved along with reduced coke rate. Application of a genetic algorithm for this type of process optimization has several advantages over the traditional optimization techniques since it can identify global optimum condition and perform multi-objective optimization much easily for complex industrial process like iron ore sintering. Keywords: Two-layer Sintering, Iron Ore Sinter Quality, Ergun's Equation, Gas-solid reaction, Melting Fraction, Multi Objective Optimization, Pareto Set, Genetic Algorithm

Jan 1, 2003

By Michael Fahey, Ravi M. Damodaran, Brij M. Moudgil

The flotation behavior of Florida phosphates was studied using statistical design of experiments to evaluate conditioning parameters and their effect on flotation performance. The solids loading, conditioning time and agitation speed during conditioning were identified as the important variables affecting the reagent coating onto particles. Flotation of the conditioned slurry was carried out at fixed collector dosage and flotation conditions. Phosphate recovery upon flotation was statistically modelled as a function of the conditioning variables. The results indicated that the conditioning variables had an interactive effect on the phosphate flotation performance. Statistical optimization revealed two conditioning regimes in which optimum flotation recovery was obtained. It was determined that optimal recovery can be obtained at lower conditioning energies.

Jan 1, 1995

By M. Louarrat, G. Enaime, A. Yaacoubi, A. Baçaoui, J. Blin

"The purpose of this study is to prepare a new activated carbon from olive stones for use in gold recovery by carbon-in-leach (CIL) and carbon-inpulp (CIP). The preparation method chosen was physical activation using steam. The effect of four process parameters: the residence time for carbonization, the activation temperature, the residence time for activation, and steam flow, were studied by the mean of response surface method (RSM) in order to optimize the yield, iodine index, and attrition characteristics. These two last responses were used as primary indicators of gold recovery capacity and mechanical strength. The results obtained show that optimal activated carbon can be prepared under the following conditions: a carbonization time of 157 minutes, activation at 921°C for 53 minutes, and a water vapour flow of 0.18 mL/min. This optimum carbon has an iodine value greater than 1100 mg/g and an attrition index in the order of 0.74%. These values reflect the quality of the precursor (olive stones) as a raw material for the development of an effective new activated carbon for the gold mining industry. IntroductionActivated carbon is an effective adsorbent widely used in industry due to its high surface area, well-developed reproducible microporous structure, and high degree of surface reactivity and adsorption capacity. World consumption of activated carbon is steadily increasing. It is primarily used in industrial wastewater and gas treatment and also for silver and gold recovery from cyanide solutions (Syna and Valix, 2003; Soleimani and Kaghazchi, 2008; Buah and Williams, 2010; Eddy et al., 2011). However, activated carbon is expensive and it needs to be regenerated after each adsorption cycle. In order to decrease the cost of manufacturing activated carbon, low-cost forest and agricultural wastes are considered promising new materials. In recent years considerable research has been reported on activated carbon from agricultural wastes, such as olive stones (Yavu et al., 2010), acorn shells (Sahin and Saka, 2013), peanut shells (Wu, Guo, and Fu, 2013), grape seeds (Jimenez-Cordero, 2014), coconut shells (Yalcin and Arol, 2002; Gratuito, 2008), palm shells (Sumathi, 2009), cherry stones (Jaramilloa, Gomez-Serrano, and A´lvareza, 2009), macadamia nut shells (Eddy, 2011), apricot stones (Soleimani and Kaghazchi, 2008), and bagass (Syna and Valix, 2003)."

Mar 1, 2019

By Akira Kaneda, Nozomu Hasegawa

"In the Mitsubishi Continuous Copper Smelting and Converting Process, slag/matte mixture overflowed from the smelting furnace is separated continuously in an electric furnace (slag cleaning furnace, CL-furnace). In order to improve the separation efficiency of slag and matte and to minimize power consumption, the design and the operating conditions of the CL-fumace should be optimized. In the previous study, the authors developed a mathematical model for simulating phenomena in the CL-furnace. The model consisted of 3 modules, electric field analysis, heat and fluid flow analysis and the particle tracking method. In this study, the model was partially modified: k -E. model was adopted, and the effects of various conditions, such as furnace shape (including accretion) and scale, electrodes configuration, immersion depth of electrodes, and thickness of slag layer, were evaluated. And the optimum design and operating conditions were discussed.IntroductionUnder the recent environmental restriction, advantageous features of the Mitsubishi process have attracted much attention. The process uses 3 furnaces connected by launders. Mixture of matte and slag formed in a smelting furnace flows continuously to a slag cleaning furnace (CL-furnace), where the matte is separated from the slag. The matte is continuously siphoned out to a converting furnace and converted to blister copper. The slag overflowed from the CL-furnace is discarded. Because the slag contains about 0.6 % copper, improving slag/matte separation efficiency and decreasing copper loss make a great profit. Moreover the process requires a large amount of electric energy, so reduction of electric power consumption brings in enormous benefit.The objective of this study is to optimize the design and the operating conditions of the process, especially the CL-furnace. This will be achieved by developing the mathematical model and clarifying relations between the design or the operating conditions and various phenomena in the furnace. Fig. 1 shows an outline of the CL-furnace. The mixture entering through an inlet is separated to slag layer and matte layer . In order to maintain the temperature of the melt at a predetermined level, 6 electrodes are immersed into the lag and Joule's heat is generated by 3-phase alternating current flowing."

Jan 1, 2000

By C. A. Rawlins, P. Rostami

"Ventilation systems are not only an integral part of any underground mine design but are a significant contributor to the mine’s capital and operating costs. The ventilation and cooling design systems presented in this paper were part of the prefeasibility evaluation of an underground platinum mine in South Africa. The mine would ultimately operate at the depth of 1,200 m below surface with a proposed 4 Mtpa production rate. The proposed mining operation is a highly mechanized operation using diesel equipment. Significant daily production rate, large amount of equipment and expansive nature of the operation, contributed to a challenging while flexible ventilation design requirements. This paper presents how to safely and efficiently optimize capital expenditure and operating costs associated with the mine air cooling and refrigeration system through practical ventilation design practices. Successful capital and operational savings by modulating installation and commissioning of refrigeration facilities can influence the economic realization of such systems. The adapted planning and design approach provided a cost-effective advantage while complying with design safety and regulations. INTRODUCTION This paper outlines a prefeasibility evaluation of the heat loads and related cooling system to be employed at the proposed platinum mine. The paper also provides appropriate details for a comprehensive understanding of the applied methodology. The proposed mine will be a trackless underground operation using a combination of mining methods. Initially, ore zones with vertical thicknesses greater than or equal to 18 m will be mined using the long-hole stoping (LHS) method, while thinner ore zones will be mined using mechanized drift-and-fill or drift-and-bench methods; hence, a highly mechanized operation with LHDs, trucks, drill rigs, personnel carriers, etc. is envisioned. Broken rock (ore and waste) will be transported by the means of trucks to the main passes (ore and waste) and collection points. Mining zones identified in the project occur at depths ranging between approximately 700 m to 1,600 m below surface. Primary access to the mine will be via a 1,100 m deep, 10 m diameter production shaft (named Shaft No. 2), three additional shafts will be sunk to provide future ventilation and production support. Three main access levels are established as primary haulage levels and include a series of interconnecting ramps. Additional mining sublevels will be developed as necessary. Figure 1 shows the proposed shaft locations and main access levels in a 3-D elevated view. Mining is performed using highly productive mechanized methods. For this reason, an annual ventilation estimate is based on requirements for mobile equipment (i.e., 0.06 m3/s/kW). The air requirements imposed on the underground operation is further influenced by equipment heat loads, auto compression, and virgin rock temperature, as the main sources of in-mine heat."

Jan 1, 2015

By C. Birch

"Mineral reserve statements as well as optimizing mine planning require a block model with grades for each mining block. A cut-off grade is determined by considering the mining costs as well as the expected revenue for each block. These grades are estimated using various techniques, but in reality there is uncertainty in the grade values. These uncertainties result in two types of error. A type I error is where material is classified as ore and mined, but the true value is below the cut-off grade and the material is therefore waste. This material constitutes dilution. The type II error is where material is estimated to be below the cut-off grade and is classified as waste, whereas the true grade is actually above the cut-off grade. This material is not mined and the value is lost.This research considers the value of the lost ore and the costs of dilution under various degrees of uncertainty. Simulation using @Risk and mixed integer linear programing (Excel Solver) is used in a financial optimizer model to maximize either profit or net present value. This is applied to four Witwatersrand tabular gold deposits to investigate the impact of block grade uncertainty on cut-off grades.When optimizing for profit, value may be added by adjusting the cutoff grade slightly downwards. When optimizing for NPV, value may be added by lowering the cut-off grade significantly for the lower discounting rates. At higher discount rates, the lowering of the cut-off grades should be reduced, and in some cases an increase in cut-off grade may be required. Each mine reacted differently to the optimization and thus there is no single rule that can be applied across all tabular Witwatersrand gold deposits."

Jan 1, 2017

By Qiong Wu, Qinghua Gu, Yichuan Lv, Jin Yuan, Caiwu Lu

"The cut-off grade is one of the important parameters of mining production. Different material cut-off grade is directed to different destinations. Based on reasonable and optimal cut-off grade, long term mining plan and investment decision analysis can be made for mining managers. In view of multiple-metals open-pit, the paper has proposed that multiple-metals cut-off grade optimization model is set using the objective function to maximize net present value (NPV). The method of equivalent coefficient calculation is proposed to convert multi-metals cut-off grade optimization to a single metal cut-off grade optimization. Then the optimization model is applied in a molybdenum and tungsten large open-pit mine in china. The parameters of concentrate price are calculated by PRT in the model and the curve of grade-recovery rate is analyzed and studied according to actual production data. Based on 3D metal deposit model, the distribution of grade-tonnage is analyzed. At final step, an optimal cut-off grade is proposed to guarantee to maximize NPV. The example shows that the model of multiple-metals cut-off grade optimization can provide reasonable analysis for optimal multi-metals cut-off grade and develop optimal production strategies. Introduction Cut-off grade is one of the most important parameters in metal ore mining because of its influence on the overall economic profit of mining production. Along with the development of the mining production, dynamic optimization of cut-off grade is necessary through the analysis of technical economy. It is better to manage the mining production according to the variation of market. The cut-off grade plays an important role in mining production."

Jan 1, 2017

By Donald R. Clark

Drilled shafts are being used as foundation support for parabolic solar troughs at the Genesis Solar Project being constructed near Blythe, California. Three types of drilled shaft foundations are required for the project. At project build-out, there will be a total of 23,008 drilled shafts installed at the site. Preliminary designs for the axial and lateral capacity of the drilled piers were based on conventional geotechnical engineering methodologies and soil-structure interaction. The drilled shafts and subsurface conditions were modeled through the use of the computer program LPILE v6.0. Conducting lateral load testing of drilled shafts was considered appropriate to confirm or modify the geotechnical parameters used in the preliminary design. The lateral load testing program was conducted to provide site-specific test data that would allow the design engineers (both geotechnical and structural) to predict the actual performance and adequacy of the proposed drilled shaft foundations and improve the efficiency and hopefully reduce project costs. The lateral load testing was conducted within two solar fields at the site. Three pairs of drilled shaft foundations were installed in each field, instrumented, and laterally loaded to determine load-deflection response. A value-engineered option, proposed by one of the drilled shaft contractors, was also load tested. The results of the load-deflection data obtained in the field was used to modify the soil modeling used in the original L-PILE analyses and adjust the production drilled shaft lengths. Based on the results of the lateral load testing, the in-situ moduli of the subsurface soils were significantly increased over that assumed in the preliminary analyses. Based on the final soil-structure interaction analyses, the preliminary drilled shaft lengths were reduced by 2 to 2-1/2 feet. This resulted in an overall reduction of 55,654 feet of drilled shaft construction on the entire project, a savings of approximately 16.5% over the preliminary design.

By Donald R. Clark

"Drilled shafts are being used as foundation support for parabolic solar troughs at the Genesis Solar Project being constructed near Blythe, California. Three types of drilled shaft foundations are required for the project. At project build-out, there will be a total of 23,008 drilled shafts installed at the site. Preliminary designs for the axial and lateral capacity of the drilled piers were based on conventional geotechnical engineering methodologies and soil-structure interaction. The drilled shafts and subsurface conditions were modeled through the use of the computer program LPILE v6.0.Conducting lateral load testing of drilled shafts was considered appropriate to confirm or modify the geotechnical parameters used in the preliminary design. The lateral load testing program was conducted to provide site-specific test data that would allow the design engineers (both geotechnical and structural) to predict the actual performance and adequacy of the proposed drilled shaft foundations and improve the efficiency and hopefully reduce project costs.The lateral load testing was conducted within two solar fields at the site. Three pairs of drilled shaft foundations were installed in each field, instrumented, and laterally loaded to determine load-deflection response. A value-engineered option, proposed by one of the drilled shaft contractors, was also load tested. The results of the load-deflection data obtained in the field was used to modify the soil modeling used in the original L-PILE analyses and adjust the production drilled shaft lengths.Based on the results of the lateral load testing, the in-situ moduli of the subsurface soils were significantly increased over that assumed in the preliminary analyses. Based on the final soil-structure interaction analyses, the preliminary drilled shaft lengths were reduced by 2 to 2-1/2 feet. This resulted in an overall reduction of 55,654 feet of drilled shaft construction on the entire project, a savings of approximately 16.5% over the preliminary"

Jan 1, 2017

By B Mohanty, G Ludwig

A thorough assessment of development drilling and blasting practice was carried out at two underground mines at INCO operations in Thompson, Manitoba. The study showed that significant improvement in productivity can be achieved through careful selection of explosives and loading practice, and modifications of the standard blast lay-out. The analysis involved assessment of the effectiveness of various perimeter blasting methods, employing selected explosives and loading practice in both jumbo and jack-leg rounds. The blasting pattern as well as burden and spacing were varied to determine their effect on the blast results. The various types of explosives used were, pneumatically loaded ANFO, with and without detonating cord tracing, extra-strength detonating cord, and slurry and emulsion explosives with and without cord tracing. The study also dealt with various means to achieve increased rate of advance in both jumbo and jack-leg rounds. The diagnostic measurements consisted of VOD, 'burn' marks or half-barrels on perimeter wall, and blasting vibrations. The effects of geology, firing sequence, blast lay-out, and drill hole deviation on the final results were also examined. The results of the study have been shown to have very important bearing on the design of development round blasting.

Jan 1, 1998

By Huamin Li

Mine # 8 of Pindingshan Coal Group, Henan Province, China has an annual production 2 million metric tons. But it encounters many problems, e.g. mine layout is complicated, roadway maintenance is difficult, coal and gas outbursts are severe, production cost is high, etc. The major reason was due to the additive effects of abutment pressure interaction of previous mining in D, E, and F seams. At the request of mine management, an in-depth systematic analysis including underground observation, modeling with simulated materials, and photoelastic experimentation was performed to obtain site-specific results which include the dynamic and static influence zones of mining D, E, and F seams, propagation characteristics of abutment pressure in the floor strata, interburden movement caused by undermining, etc.

Jan 1, 2000

By John C. Niedzielski

The existing US-70 Bridge over the Gila River at Bylas, Arizona is planned to be replaced due to its current poor condition. The replacement bridge is planned to be a 15-span, 1,904-foot (580 meter) long bridge, the third-longest bridge in the state highway system. Within the Gila River floodplain, granular alluvial soil is underlain by cohesive lacustrine soil; bedrock was expected due to nearby terrain but not encountered within the geotechnical exploration depth of 166.5 feet (51 meters) or less. Based on the anticipated loading conditions, design scour depths and the soil conditions, the full structural loads are carried by large diameter drilled shafts; therefore accurately determining the axial capacity of the proposed drilled shafts has important practical and safety implications. The conventional methods for axial capacity determination may be overly conservative to use for design in the site?s layered granular and hard clay soils. An Osterberg cell load test was performed to obtain detailed information on the load transfer from the drilled shaft in side friction and base resistance to allow optimization of the bridge foundation design. The full-scale field test played a significant role in the design of the project?s deep foundations, notably, by incorporating the specific subsoil properties and consequently, an exact prediction of the load-settlement behavior under loading. This paper provides the results of the geotechnical site investigations, drilled shaft load testing procedures, and shaft load distribution from the load test results. Comparisons were developed between predicted axial capacities of drilled shafts using several design methodologies and the axial capacity measured from static load testing. The load test results showed that underestimation of the axial capacity is evident using conventional methodologies. The exact prediction of the load-settlement behavior under loading combined with a site-specific design approach, resulted in a substantial reduction of foundation costs due to reduced drilled shaft dimensions.

By John C. Niedzielski, A. Frances Ackerman

The existing US-70 Bridge over the Gila River at Bylas, Arizona is planned to be replaced due to its current poor condition. The replacement bridge is planned to be a 15-span, 1,904-foot (580 meter) long bridge, the third-longest bridge in the state highway system. Within the Gila River floodplain, granular alluvial soil is underlain by cohesive lacustrine soil; bedrock was expected due to nearby terrain but not encountered within the geotechnical exploration depth of 166.5 feet (51 meters) or less. Based on the anticipated loading conditions, design scour depths and the soil conditions, the full structural loads are carried by large diameter drilled shafts; therefore accurately determining the axial capacity of the proposed drilled shafts has important practical and safety implications. The conventional methods for axial capacity determination may be overly conservative to use for design in the site’s layered granular and hard clay soils. An Osterberg cell load test was performed to obtain detailed information on the load transfer from the drilled shaft in side friction and base resistance to allow optimization of the bridge foundation design. The fullscale field test played a significant role in the design of the project’s deep foundations, notably, by incorporating the specific subsoil properties and consequently, an exact prediction of the load-settlement behavior under loading. This paper provides the results of the geotechnical site investigations, drilled shaft load testing procedures, and shaft load distribution from the load test results. Comparisons were developed between predicted axial capacities of drilled shafts using several design methodologies and the axial capacity measured from static load testing. The load test results showed that underestimation of the axial capacity is evident using conventional methodologies. The exact prediction of the load-settlement behavior under loading combined with a site-specific design approach, resulted in a substantial reduction of foundation costs due to reduced drilled shaft dimensions.

Jan 1, 2017