Search Documents

By Swaminathan Srinivasan, Aaron J. Muck

"When an opportunity arises to combine state-of-the-art concepts with advanced modeling tools, engineers need to take what they know and apply forward thinking to geotechnical solutions to promote the state-ofpractice. Such an opportunity was seized during the design and construction of the Great American Tower in Cincinnati, Ohio. The forty-one story Great American Tower at Queen City Square – currently the tallest building in Cincinnati – has not only changed the downtown skyline, it is also contributing to the advancement of the state-of-the-art use of auger cast-in-place (ACIP) piles as settlement reducers. Predicted settlements of a traditional mat foundation were excessive, and the costs and construction time associated with traditional ACIP piles extending to bedrock were not preferred. A mat supported on a limited number of ACIP piles, with the piles primarily acting as settlement reducers, was evaluated as the preferred foundation type.Promoting the unique soil-structure interaction of the foundation system with confidence required the use of sophisticated numerical modeling tools. Traditional standard penetration test boring data (SPT) was initially used to develop a numerical analysis of the soil-structure interaction using FLAC 3D software. The model was further modified with cone penetration (CPT) and pressuremeter testing (PMT), along with actual load test results on several ACIP pile elements of varying lengths, but all tipping above bedrock. Through a combined design team effort, and detailed numerical modeling analysis, ACIP piles were recommended for reducing mat foundation settlement. Instrumentation during and post-construction confirmed design assumptions and predictions. Integrating sound geotechnical concepts, and using advanced geotechnical analysis and design methods, traditional mat and ACIP pile foundations were successfully integrated into a unique foundation support system.INTRODUCTIONThe Great American Tower at Queen City Square in Cincinnati, Ohio is located within a region dissected by historical geologic deviances associated with the meander of the Ohio River and glacial progression/recession. Combining a challenging geology, with the development of a high-rise office building afforded the design team an opportunity to combine state-of-the-art soil-structure interaction concepts and method with traditional geotechnical engineering concepts. Such a combination required a variety of field tests, collaboration with the design team and owner, and geotechnical-structural modeling during the design phase. During construction, in addition to materials testing and observation, a variety of instrumentation systems were employed. Together, the data was used to corroborate the design model and make adjustments during construction and further substantiate design assumptions following construction."

Jan 1, 2015

By Brian T. Nereson, Michael C. Penney

"This technical paper was prepared to describe the general process by which the authors designed a column-supported load transfer platform (LTP) for support of asphalt-paved runway and taxiway embankment areas over soft organic soils, the major tasks and observations made during construction of the system, and the outcome of the system design and construction. The LTP system was designed using the method described in the BSI Standards Publication Code of Practice for Strengthened/Reinforced Soils and Other Fills, BS 8006-1:2010 (BS8006), to achieve performance objectives for the project. The design also used other criteria based upon the authors’ engineering experience and understanding of the expected interaction between soils, structures and geotextiles. The design and construction process described herein resulted in a successful project. The authors identified that full-time engineering oversight during construction was of high importance and provided a high degree of value to the project. The authors’ intimate knowledge of the potentially adverse effects of variations in construction practices promoted timely identification of construction deficiencies that could have affected the reliability of the system. This resulted in corrections and modifications being made, while materials were still accessible, to protect the intended performance of the finished system.INTRODUCTIONThe site is located in Marshfield, Massachusetts. The surrounding area is flat and contains significant wetlands with a water table at or near the ground surface. Prior to the improvements described herein, the site was already developed as an existing municipal airport with an approximately 3,000 linear-feet asphalt-paved runway oriented in a northeast/southwest direction (northeast end referred to as Runway 24 and southwest end referred to as Runway 6; Fig. 1). The site is located approximately 0.5 to 1 mile (Runway 24 and Runway 6, respectively) from the Atlantic Ocean.The improvement project included total extension of approximately 550 linear feet of asphalt-paved runways and taxiways over existing wetlands that consisted of soft, organic soils with varying but significant depths (Fig. 2). An initial geotechnical assessment performed for the project identified that the subsurface conditions were not suitable to support the proposed runways and taxiways in their existing state."

Jan 1, 2016

By Adrian M. Keller

Borehole televiewers are downhole inspection devices available for high-resolution imaging of a borehole wall following rock coring. Borehole televiewers should be considered by geotechnical engineers and geologists as a supplemental way of investigating rock for deep foundations. The optical televiewer (OTV) produces a digital optical image and the acoustic televiewer (ATV) utilizes reflected acoustic waves to produce images of the borehole walls. These devices can be utilized to examine soft or fractured zones in the rock mass, solution features, open joints or other voids not observable from traditional rock coring techniques. These devices along with computer post-processing can determine the strike and dip of joints, bedding planes, shear surfaces, or other structural features, eliminating the need for expensive oriented cores or manned downhole logging. An acoustic televiewer was utilized in the Fall of 2008 during the investigation phase for the I-70 New Mississippi River Bridge (I-70 MRB) in St. Louis, Missouri. Voids and fractures in the upper portion of the rock were described by prior consultants. Further investigation of these features was necessary to evaluate deep foundation options to support the main towers. Ten borings were drilled from a barge in the river at the two main tower pier locations. An ATV was utilized in each of the ten borings to produce images of the rock mass in the borehole and allow further investigation of the voids. Voids interpreted as solution features were readily identified in the ATV logs in multiple borings and at similar elevations, suggesting connectivity. Measurements of the voids? width, location in the borehole and orientation allowed a more thorough understanding of the potential impact the solution features may have on the planned deep foundations. An extensive grouting program was eliminated based on the ATV results.

Jan 1, 2010

By Lynn Crayne

We used Glyoxal as the hardener, at a final concentration of 10% by volume and therefore 20% by volume in the A-Component. They worked pretty well what we did was we shaved the joints on each of the pipes when we assembled them so they wouldn't rip the packers and then we greased the packers very well going in. We had to replace some but we have any getting stuck or didn't lose any pipes.

Feb 10, 2003

By Denis Huber

The technical assessment of the final works on the "Stéphany Palace" project at Menton in France's Alpes-Maritimes region shows the importance of daily project monitoring based on the observation method recommended by the European standard Eurocode 7 which applies to Foundations and Geotechnical Engineering. Excavation operations to a depth of 10 m near the France-Italy railway track and adjacent buildings required precise observation of land deformations, regular piezometric monitoring as well as special design arrangements. Temporary active tie-rods were thus placed in phases in order to control deformations in the retaining structures resulting from excavation operations. The Menton region, terminating the Alpine arc of mountains, naturally required the consideration of seismic forces in phase in the lower floors of the building, directly linked to the buried walls. These calculations were carried out in accordance with the PS69/92 rules, calling for an increase in dynamic thrust under the effect of gravity field rotation.

Jan 1, 2002

By Ali Ebrahimi, Jeremy M. Gasser, Cuneyt Gokmen, Paul J. Sabatini, Roneet Das, William Tanner, Amir Ahmadipur

There are safety concerns related to operation of heavy equipment over coal combustion residual (CCR) impoundments during construction of the impoundment closure programs. As part of a pilot study prior to a full-scale closure construction, an access pathway and working platform were designed and constructed to facilitate equipment access for construction of deep soil mixing (DSM) zones on the ash delta of a CCR impoundment. The access pathway and working platform was constructed using shallow mass mixing with cement at the CCR surface to address safety concerns related to the geotechnical behavior of CCR. This paper describes the data from the instrumentation system which was implemented to monitor the geotechnical performance of the CCR during the pilot study. The instrumentation system included monitoring of the ground movement, vibration, and porewater pressure within the ash delta of the CCR impoundment during a pre-construction load testing, equipment mobilization over the access pathway, and DSM column installation over the working platform. INTRODUCTION A deep soil mixing (DSM) pilot study was conducted at a coal combustion residual (CCR) surface impoundment to evaluate mix designs and construction techniques for the regulatory closure. The DSM columns will create a wall which will separate and retain the CCR in a consolidated footprint separate from the closure by removal portion of the footprint and provide a barrier between the two areas of the surface impoundment. Historically, the surface impoundment received CCRs including fly ash, bottom ash, boiler slag, and gypsum, along with other byproducts produced from flue gas desulfurization (FGD). The predominant CCR in this impoundment were fly ash and bottom ash. The primary goals of the DSM pilot study were to assess the mix design strengths and to evaluate DSM construction techniques that could reach the design mixing depths of up to 90 ft. The DSM test columns were installed on the CCR delta approximately 500 ft from the nearest impoundment dikes. Another objective of the pilot study was to develop, construct, and monitor an access pathway for safe passage and movement of construction equipment on the CCR delta.

Jan 1, 2019

By J. Racinais, P. Vincent

"In September 2011, Menard Oceania (MO) was engaged by Mac Mahon John Holland Joint Venture (MJHJV) to provide ground improvement solution for the $34bn Ichthys LNG development. With close to 400,000m2 of mangrove swampland set to be reclaimed and improved, this project was a great opportunity to showcase the technical, commercial and environmental benefits that Dynamic Replacement (DR) ground Improvement technique can provide. The ground improvement works involved complete design and construction for the Ichthys LNG site located at Blaydin Point on a low lying peninsula in Darwin Harbour. Dynamic replacement and stone columns technique were selected to treat intertidal mangrove mud to achieve required bearing strength, stability and limit settlement to an acceptable levels. The site is underlain by a 3m to 5m thick layer of highly organic mangrove muds with very soft shear strength ranging from 0kPa to 12kPa at depth. The site is exposed to daily sea water level tidal variations of up to 8m, which created significant constructability constraints and slope instability risks. This paper presents the design philosophy, the process involved in the selection of the construction methods, the site constraints encountered during the works and a review of the results achieved, quality control and post constructions performance.INTRODUCTIONInpex Browse, Ltd (Inpex) and its partner Total are developing the Ichthys gas field to pipe gas to onshore facilities at Blaydin Point on the south side of East Arm in Darwin Harbour. The proposed LNG plant consists of gas receiving facilities, 2 x 4.2Mtpa nominal capacity LNG trains, LPG and condensate production facilities, product storage and export facilities, a module offload facility (MOF), a flare pad (FP) and associated off plot facilities.The proposed on-shore facilities are located on extremely soft intertidal mangrove muds, therefore an appropriate ground improvement was required to achieve required strength and stability of site works and limit long term settlement to an acceptable level.Various ground improvement techniques were studied to select the most suitable for the ground conditions and site constraints encountered at the Blaydin point site. Dynamic replacement technique was selected for onshore section to improve soft mangrove mud to depths of 5.5m and Stone Columns (SC) technique was selected for MOF off-shore section to improve intertidal deposits to a depth of 2.5m.This paper presents DR design and construction works performed between December 2012 and August 2013 at Flare Pad Area."

Jan 1, 1900

By Dario Libano, Armando Caputo, Francisco Caputo

"UHE Peixe Angical is a 452 MW hydroelectric power plant located on the Tocantins River in Tocantins, Brazil. In 1999, geologists began feasibility studies to estimate the river’s hydroelectric potential, and the decision was made to proceed with the construction of a power plant. In 2002, after extensive investigation, the studies indicated geological homogeneity at the site for the dam, except for an anomaly detected on the left margin, and construction began on the $1.2 billion project.As the work began, the complex ground conditions presented several serious difficulties. The solution was unlike any undertaken before in Brazil— a 100-m-long secant cutoff wall, with 76 1.8-m-diameter piles of up to 78 m deep. All were placed in a six-month period.In the preparation for the detailed construction plans, further studies in the area of the anomaly better defined the geology so that a treatment program could be developed. The feasibility study had detected silicified rock with high permeability in one area, and an injection curtain was designed with five injection lines. In the other area with an anomaly, further investigation revealed a permeable marble formation that was 50 m thick. Here, a specific injection program with three injection lines was developed.The injections started in February 2005 in the marble formation area. By July of that year, only the primary and secondary holes were drilled from the three lines, resulting in a space between injections of 1.50 m. By the end of July, the drilling was halted. The contractor had identified a thick area of heterogeneous material below the transition zone that was characterized by a mixture of soil, fractured rock and hard fractured rock. The anomalies were detected while drilling, and both the general contractor and the designer concluded that the phenomenon of “piping” was taking place.Constructing a positive cutoff wall became a priority."

Jan 1, 2009

By Francisco A. Flores, Rigoberto Torres

The Complementary Technical Standards of Mexico’s City Building Code do not mention the criteria to compute the bearing capacity of Steel H-piles. It is necessary to increase knowledge in using steel H-piles as foundation elements in very soft soils of Mexico City. Considering their applicability to reinforce structures as well as new foundations in confined spaces, this research is proposed to obtain the axial load capacity of piles at scale in laboratory. This paper describes the construction and testing of scale models in laboratory of steel H-piles to measure their axial compression and tension load capacity in the soft soils of Mexico City. Three types of piles were fabricated at scale. Tests were performed on individual piles and pile groups. Based on the axial load tests, the load-displacement curves are presented both in compression and tension. The analysis of the results is shown, and comments are given regarding the ultimate bearing capacity of piles. Recommendations are presented regarding the determination of the bearing capacity of these piles in the very soft soils of Mexico City.

Sep 8, 2021

By Unnikrishnan Nair, Sandeep S. Nikam, Sanjay D. Patil, Prabir C. Basu

"Mumbai Metropolitan Region Development Authority (MMRDA) entrusted to implement Monorail Systems in various parts of Mumbai Metropolitan Region (MMR) with the objective to supplement the present transport system in MMR. The stretch of Monorail is starting from Sant Gadge Maharaj Chowk (SGMC) and extending up to Chembur Railway Station, divided into 2 phases. Construction of Phase 1 (Chembur to Wadala Depot) is complete and Phase 2 (Wadala Depot to SGMC) is under construction.Monorail runs on prestressed girder (guide beam) of span ranging from 20m to 28m supported on pier founded upon group of end bearing piles embedded in rock, pile group ranging from 2-4 piles of diameter 1000mm each.For the purpose of site characterization, geo-technical investigations were carried out along the alignment of Monorail system as mentioned above. These investigations included field and laboratory tests. The subsurface strata mainly consist of silty sand, gravel, underlain by marine clay extending up to stronger basalt rock with volcanic breccia. Overburden consisting of mainly marine clay ranging from 5.5m to 11m at all locations within the influence zone of settlement.The existing rigid pavement along of Sion-Koliwada and Anik-Wadala were constructed about 5 years prior to the construction of Monorail piers. Before laying the rigid pavement, to improve the geotechnical strength of subsoil (mainly marine clay), ground improvement using stone columns was undertaken by MMRDA. In light of limited right of way, the Monorail piers have been constructed in the median portion of the road. The line became operational on February 2014, in few months it was noticed that, in the vicinity of the Monorail piers, along Sion-Koliwada link and Anik-Wadala link, the Road Pavement Quality Concrete (PQC) panels adjacent to the Monorail piers started showing distress in form of nonuniform settlement of the concrete panels.Effect of pile foundation on pavements/PQC slab distress and possible causes of distress were investigated. Initially the distress was thought to be upheaval of monorail pier cap, but further investigations revealed the same to be soil settlement occurring over time. This paper describes the investigation carried out for identifying the cause of this settlement."

Jan 1, 2015

By Yazen Khasawneh, Osvaldo P. M. Vitali, John E. Agee, Mohammad Nassim

A 3D FEM modeling of a ground improvement solution for an ice rink slab with stringent differential settlement limits is presented. Due to the complexity of the geotechnical conditions and strict deformation requirements, a structural slab supported by micropiles was initially proposed. However, this solution was costly and alternative solutions using ground improvement techniques were investigated. The proposed slab is supported directly on rock at one end and on approximately 45-ft deep cohesive soils on the other end. The numerical simulations show that differential settlement would be larger than allowable, if the ice rink slab is supported directly on the existing subgrade. The addition of the ground improvement scheme with compaction grouting demonstrated that the anticipated differential settlements are reduced significantly and would become less than the allowable magnitude. This study demonstrates that the use of numerical simulations to study complex loading and geological conditions will help to optimize designs and may result on significant cost savings.

Sep 8, 2021

By Peter Deming

"PART 1 OF 2INTRODUCTIONSlurry trenches are the least cost hydraulic barrier available, if the excavated spoils can be recycled into backfill. As such, slurry trenches are constructed where possible, sometimes at high risk. Slurry trenches are also used to install biopolymer drainage trenches, which have a low safety factor because the biopolymer slurry weight is marginally greater than the weight of water. In marginal ground the construction risk falls to both the Owner who designs and asks for the construction, and the Contractor who manages the work and promises to complete the project successfully. This paper discusses design and construction of slurry trench barriers in marginally stable ground and where groundwater chemistry invokes the need for slurry management details to obtain proper backfill placement.As a designer, Mueser Rutledge Consulting Engineers works for both Owners and Contractors. We are usually able to convince Owners of their responsibility for design detailing in order to obtain a working final product and to obtain reasonable bids from Contractors by disclosing construction needs and designing to reduce the contractor’s exposure. We often work for Contractors to produce designs which result in successful construction in projects where the Owner’s engineer places the responsibility of design and construction on the Contractor.This paper is intended to inform both Owner and Contractor audiences of resources which are available to reduce the risks of trench collapse in difficult ground conditions. We hope it serves this purpose.DESIGNSubsurface InvestigationsSubsurface conditions should be defined by borings focused on definition of the soil profile and soil design parameters. After general subsurface conditions are defined, barrier borings should be drilled along the final alignment.Definition of Soil Strength and CompactnessCompactness of sand and gravel strata should be defined with Standard Penetration Test N-values. The shear strength of cohesive materials should be defined by laboratory testing. Silt and fine sand strata with little cohesion should be investigated using mud rotary techniques to prevent disturbance. General strength characterization by soil layer should be used for analysis of trench wall stability."

Jan 1, 2006

By Gordon Chen

As part of a value engineering envisioned by East Coast Slurry, Weidlinger Associates, Inc. designed a unique elliptical slurry wall cofferdam for construction of the 65 ft. deep MWRA North Dorchester Pump Station. A conventional rectangle cofferdam with multiple levels of bracing would have been time consuming and costly and imposed a significant obstruction to the pump station construction. A circular slurry wall, while eliminating the bracings, conflicted with adjacent structures and required excessive backfilling around the final pump station structure. The ellipse shaped cofferdam fit the needs of the project well; however, it created a significant design challenge without the use of bracings. Unlike a circular cofferdam which primarily only has hoop stresses, the ellipse still has to be designed for horizontal bending moments in each panel because of the non-axial symmetric conditions. The more eccentric the cofferdam shape; the higher the horizontal bending. The challenge was to develop a three dimensional finite element model that could analyze both the hoop stresses and horizontal bending stresses above and below the bottom of excavation induced by soil and water pressure and unbalanced construction surcharge loads. This paper discusses the techniques used to model the soils and structure interactions and results of stresses on this challenging unbraced configuration.

Jan 1, 2010

By Shawna Munn, Sarah Speir

Cedarvale Station is one of 25 new Eglinton Crosstown light rail transit (ECLRT) stations along Eglinton Avenue in Toronto. It is an interchange station with the existing Toronto Transit Com- mission (TTC) University subway line and is located at the intersection of two major thoroughfares. The new LRT tunnels run below the existing Yonge Spadina subway line and required total excavation depths of 20 m (65 ft) to facili- tate construction of the new station.

Jan 1, 2023

By I. D. Dayal, Anil Kumar Jain

"Cutoff walls are frequently used to slow down or prevent seepage of water through and/or around dams. Cutoff wall is a type of seepage barrier structure designed to reduce the flow of water underneath temporary or main dam. There are number of techniques for the construction of cutoff walls including concrete, Jet grouting and permeation grouting. NHPC LTD, a premier Govt. of India undertaking has been instrumental in the hydropower development within the country & in nearby countries like Nepal & Bhutan since last four decades. NHPC LTD has completed more than 20 hydro-electric projects with total installed capacity of 6587MW (including capacity addition by JV- NHDC). In all these projects, different types of dams and spillways were constructed in not so benign to extreme challenging geological set up. There has always been challenge associated with the temporary diversion works. The project sites sometimes incur huge river bed excavations in case of concrete gravity dam founded on rock foundation at large depth. The challenges for minimizing the seepage have been well taken care by constructing the dedicated seepage barriers. The construction of cut-off walls have progressed from “conventional continuous trench backfilled with conventional concrete or plastic concrete” to “grout curtain”, to “jet grouting” to the “concrete cut-off wall” , the last being the most sophisticated & credible seepage barrier.The efficiency of the cut-off walls are monitored by the seepage quantity observed (reduction of the seepage flow), uplift pressures or exit gradients after construction of cut-off walls. For construction of the main concrete dam, required space is created by the river bed excavation for placing the dam foundation on sound rock. Sometimes there is deep river bed excavation from 30 to 40 m depth or even more as per the available rock profile. Temporary coffer dams are constructed for diverting the river flow through diversion tunnels / channels etc. In deep river bed excavation; there are high chances of the significant seepage through the coffer dam foundation / river bed material due to high hydraulic gradients. Seepage and piping are the main causes of the failure / damage of the temporary coffer dams. If the seepage quantity is too high, then it becomes difficult to handle it by dewatering in the dam pit. Dam concrete is required to be placed unhindered to have a monolithic construction of dam blocks & to have faster construction in the working season. Cut-off walls increase the seepage path considerably thus reducing the exit gradient and further reduction of the seepage thus helping in maintaining the seepage free area for working."

Jan 1, 2016

By Nabil F. Ismael

"Load tests were carried out to examine the ultimate bearing capacity of short, large diameter bored piles in connection with the construction of a multistory building on the Arabian Gulf in Kuwait. Testing included 0.45 m, 1.0 m, and 1.2 m piles installed through loose sand into a bearing stratum consisting of very dense cemented sands. All tests were carried out to failure. The base resistance and shaft friction were calculated using the Meyerhof method for a layered soil profile. The method employs the standard penetration test N-values. The results indicate that the piles are end bearing piles with a great portion of the pile capacity due to base resistance. The mobilized skin friction is small. The calculated pile capacities were very close to the measured values with the maximum difference not exceeding 10%.INTRODUCTIONShort, large diameter bored piles are used with increasing frequency for heavy structures in Kuwait, and the Gulf region where ground conditions indicate loose deposits of calcareous sands. The piles range in length from 8 m to 15 m with their base located in the dense-to-very dense, cemented sand bearing deposit. The design of these piles requires knowledge of the skin friction and point resistance in these soils. While field tests on driven piles are available (Ismael 1989, Ismael 1999), field test data on large diameter bored piles installed through loose calcareous sands into dense-to-very dense cemented or partially cemented sands are very limited at present. The results of three load tests carried out recently on bored piles at one site in Kuwait have become available. In these tests the failure load was either reached or can be extrapolated from the test results. It is important to examine and analyze the test results for the benefit of the geotechnical research and design engineers.This paper presents the soil conditions, pile installation details, and the pile load test data at the test site located in Shuwaikh, Kuwait. The site is facing the Arabian Gulf. Test results were directly analyzed and the point resistance, and skin friction were calculated. The ultimate capacities of the piles were calculated and compared with the measured values. The influence of the pile diameter on the settlement at ultimate and at working loads is examined"

Jan 1, 2017

By Fred Fuchs

"Most deep foundation work is either unseen by the general public or viewed as an inconvenience in their daily lives. Hurricane Katrina changed that perspective for everyone in New Orleans — and many other people in the U.S. and abroad. The public and the government of south Louisiana, and the U.S. Army Corps of Engineers (USACE), all needed to restore trust in the system that protects their property and, more importantly, their lives. While much has been written about the failures of government agencies, in this case incredible solutions were devised and implemented despite daunting schedules and arduous conditions. These solutions were achieved through collaboration, and through the efforts of USACE, where the goal was to fi nd the most expeditious and effective design/build solutions. This disaster thrust the pile driving industry into the national spotlight. Boh Bros. Construction Co., L.L.C., along with numerous local and national heavy construction companies, subcontractors, material suppliers and government agencies, take pride in the milestones reached after Hurricane Katrina.The majority of New Orleans’ population lives below sea level. Historically, the city has been protected by a fl ood control system consisting of earthen levees and I-walls (steel sheet pile topped by vertical concrete wall). Rainwater is pumped out of the city over this protection system and into canals that feed into Lake Pontchartrain. On August 29, 2005, when Hurricane Katrina made landfall just east of the city, the levee system experienced a major failure of several I-walls lining the outfall canals, causing flooding of 74% of the east bank of the city. The counterclockwise rotation of the wind pushed the lake water onto the south shore, raising the level of water more than 10 ft (3 m). A failure of 450 ft (137 m) of floodwall lining the east side of the 17th Street Canal caused extensive damage. This breach prevented the use of the pump stations that outfall into the 3-mile (4.8 km) long 17th Street Canal."

Jan 1, 2008

By Terry Eldridge, Keith MacKay, David Siddle, Luke Moger

On August 4th, 2014, a breach occurred in the Perimeter Embankment of the Tailings Storage Facility (TSF) located at the Mount Polley Mine, releasing approximately 10.6 million m3 of supernatant water, 7.3 million m3 of tailings solids, 6.5 million m3 of tailings interstitial water and 0.6 million m3of construction materials. A Temporary Upstream Rockfill Berm was constructed between August 2014 and February 2015 within the area of the tailings dam failure in order to retain the remaining tailings solids during the low flows of the winter season. The Temporary Upstream Rockfill Berm was constructed as part of the initial response phase, with the primary objective to abate the flow of tailings into the receiving environment. A secondary objective of its construction was facilitating the required investigation works downstream of the tailings dam failure. The selection of the coarse grained material used in the construction of the Temporary Upstream Rockfill Berm was based on the availability of the material (timeliness of construction) and the non-water retaining design of this initial response phase. Consequently, an alternative method was required in order to prevent further loss of mine-affected water and tailings from the TSF, as well as to provide short-term contingency water storage, during high flow conditions expected in late spring. Golder Associates Ltd. designed the 2015 Freshet Management Embankment, a deep mixing cut-off wall, to meet these site requirements, which was constructed by Mount Polley Mining Corporation and Golder Construction Inc. between December 2015 and April 2015. The works included 132 soil cement panels constructed to depths of up to 27 meters. This aspect of the works was completed using an RG25S Bauer CSM rig on a 24 hour per day, 7 day per week schedule. The cut-off wall specifications included a target unconfined compressional strength (UCS) of between 1 and 2 MPa, a maximum hydraulic conductivity of 1x10-6 cm/s, and a ductility to enable the soil cement to undergo a minimum of 5% strain without a reduction in strength or increase in hydraulic conductivity. In order to control and assure the quality of the soil cement, 2553 wet grab specimens were retrieved from the fresh soil cement panels using a project-developed sampler. Four of the soil cement panels were cored with a mud-rotary drill rig and optical and acoustic televiewers were placed into the boreholes in order to log several relevant parameters, including image, texture, relative hardness, borehole-shape, and temperature.

Jan 1, 2016

By Kenneth Gavin, Weichao Li, Paul Doherty

"The lateral load capacity is one of the most important issues to be considered in designing piles to resist berthing loads, ship impact forces and for monopiles used in the offshore wind sector. A number of semi-empirical design approaches are available to calculate the ultimate soil resistance and assumed soil reaction profile along the piles’ embedded depth. In order to investigate the response of monopiles to lateral loading, a series of field experiments were conducted on instrumented steel pipe piles. Two lateral loading tests were performed on model piles with a diameter, D, of 340 mm and embedded depth, Lem, of 2.2 m, giving a Lem/D ratio similar to those adopted in the offshore wind sector. The piles were driven into dense sand at the University College Dublin geotechnical test bed site in Ireland. 10 pairs of strain gauges were installed on each model pile along the embedded depth at 10 levels to capture the load transfer and bending moment within the piles. The deflection and rotation at the model pile head were measured by Linear Variable Differential Transformer (LVDT) and inclinometers. The tests results were used to perform a detailed evaluation of current design methods. In the final section, discussion on the determination of the ultimate lateral load capacity for monopile design was conducted. IntroductionA pile’s lateral load capacity is determined, for design purposes, by two conditions: 1) the ultimate lateral load, Fu, divided by an appropriate safety factor; and 2) the load according to the maximum lateral deflection that the support structures can sustain. In view of the first condition, design methods to calculate the ultimate load were developed for piles used in the offshore oil and gas sectors, which tend to be much more slender than monopiles used in the wind industry. The purpose of this study was to investigate whether these design methods provide reasonable estimates of ultimate capacity, for short rigid monopiles.The methods to determine the ultimate lateral load generally follow three steps: 1) determine the ultimate soil resistance, Pu, along the pile embedded depth; 2) adopt the most appropriate soil reaction profile, Pz, along the piles embedded depth when the pile subjected to the ultimate lateral load condition (four of the most popular ones are depicted in Figure. 1); and 3) ensure equilibrium of lateral forces (see Equation 1, symbols are listed at the end of the paper) acting on the pile and bending moments (see Equation 2) about a point in pile is employed to determine the ultimate lateral load."

Jan 1, 2015

By Thomas J. Kennedy, Michael D. Bennett

The study of geotechnical history is well-established. Most geotechnical practitioners, teachers, and graduate students have some grasp of the origins of the field. However, this understanding often consists of a jumble of names and anecdotes. This paper discusses how a deeper comprehension of geotechnical history can benefit academia and practice alike and describes how the authors have begun a wide-ranging study of the subject. The paper reviews the dual-track methodology the authors have generated for the study, which consists of written articles about different works in geotechnical history and a database tracking how often pieces have been cited in geotechnical literature. The first technique has shed light on aspects of geotechnical history such as the connection of the Darwin family to the origins of geotechnical engineering, the St. Francis Dam failure of 1928, and the rivalry between theoreticians and practitioners in the early days of the field. The second has helped quantify subjects such as the outstanding contributions of Karl Terzaghi, the disagreements between Terzaghi and Donald Taylor, and the specialization of the field over time. The paper concludes by discussing the authors’ planned future work on geotechnical history.

Oct 1, 2022