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By Jason Herron, Joseph Brown

The common couplings for joining sections of helical piles with an outside diameter of 6.625 inches and 8.625 inches are square on square, flange to flange, external pipe sleeve, internal pipe sleeve, and welded joint. Each coupling type has advantages and disadvantages in efficiency, capacity, installation, and economics of the installed pile. All these coupling types have been used in the helical pile market in North America for various applications and designs. Many of these applications require on-site testing, but test records are not typically shared with the helical pile industry. Due to the lack of information available for square on square and flange to flange couplings, testing was done to compare the efficiency of installation, load to deflection response, and torque to capacity ratios of external pipe sleeve, square on square, and flange to flange couplings. Field installations and tension tests were performed in non-cohesive (sand type) soil near Caseyville, IL and in cohesive (clay type) soil in Centralia, MO. The data collected during these tests included rotations per foot during installation, installation torque, applied pressure, and deflection. The results of this testing are analyzed and discussed within this paper. The results indicate that the square to square coupling is the most efficient of the designs tested, but this conclusion cannot be fully justified without further testing due to the variability in the data gathered and the small number of piles tested. INTRODUCTION A helical pile is typically assumed to be a medium-displacement pile when its outside diameter is between 4.5 inches and 8 inches and a high-displacement pile when its outside diameter is greater than 8 inches. A helical pile designer has multiple options when selecting a coupling type for medium- to high-displacement helical piles. Each type of coupling has advantages and disadvantages and must be analyzed on the bases of efficiency, capacity, installation, and economics of a project. Typical couplings that are chosen by designers include square on square, flange to flange, external pipe sleeve, internal pipe sleeve, and welded joint. A helical pile must transfer axial, lateral, bending moment, and torsional loads, and the coupling must be designed to effectively and efficiently transfer each type of load. During the installation of a helical pile, the rate of penetration and the disturbance of soil layers play a critical role in the efficiency and torque to capacity ratio (Kt) of the pile. It is common for a coupling to protrude beyond the outside diameter of the pipe section being used. This is necessary for the function of certain coupling types and can facilitate the connection of couplings. However, it causes increased soil disturbance and reduce the rate of penetration due to soil bearing against the protruding portion of the coupling. A helical pile designer typically will work to minimize the coupling protrusion and create a pile with optimal installation efficiency but may choose a design with lower installation efficiency if it offers sufficient economic advantage.

Jan 1, 2019

By Shigenori Horikawa, Nobutaka Tanaka, Toshiro Hara, Kengo Yamamoto

"The CDM-LODIC method(Low Displacement and Control method), a modified the CDM(Cement Deep Mixing) method, reduces the ground displacement through the removal of in-situ soil equivalent to the amount of slurry injection using the continuous auger flight attached on the shaft above the conventional the CDM mixing tool. The reduction of ground displacement minimizes the impact on adjacent buildings and other infrastructures. Since the development of the CDM-LODIC in 1985, this method has been used for more than 900 projects with total volume of improved soils exceeding 5.3 million yd3 (7 million m3). The ground displacement that could be caused by deep soil mixing is controlled by balancing the volume of discharged soil and the volume of slurry injected for soil mixing. This paper presents the ground improvement work for the Sanriku Coast Expressway Project using the CDM-LODIC method to 1) control the ground displacement during ground improvement to minimize the impact to existing buildings and facilities and 2) utilize low height CDM-LODIC equipment to avoid potential damage to critical facilities in the vicinity of ground improvement area and avoid interference on the normal operation of the Ishinomaki Red Cross Hospital.INTRODUCTIONSanriku Coast Expressway is a reconstructed highway, which is part of an early restoration program to recover from the Eastern Japan Earthquake of March 11, 2011. This highway extends 223 mile (359 km) and connects the Pacific Coast regions of three prefecture of North Eastern Japan as shown in Figure 1. Along a section between Yamoto - Ishinomaki road, the highway was expanded from two lanes to four lanes to mitigate traffic congestion for the adjacent city center and hospital and to serve as an efficient transportation route for emergency or disaster relief needs as shown in Figure 2. Deep mixing ground improvement with an area replacement ratio of 50% was designed to provide settlement control under the new fill embankment of the expanded highway as shown in Figure 3. The original CDM treatment layout using 5.2ft (1.6 m) diameter columns is shown in Figure 4."

Jan 1, 2015

By Harald Ludwig

In 2002, excavation support work commenced on the Capitol Visitor Center project located adjacent to the nation?s Capitol building in Washington, D.C. The outlying work (Slurry Wall Work at Main Site is not discussed) consisted of providing excavation support for a new truck tunnel approximately 1900 feet long up to 50 feet deep as well as support for the new underground auditorium and Library of Congress tunnel. The excavation support consisted of a combination of conventional drilled in soldier beams, lagging, tiebacks and braces; intricate underpinning inside the existing Capitol building; support of an existing Russell Tunnel; soil nailing and tiebacks underneath the existing Russell Tunnel; two temporary bridges; and a deep soil mixed wall with lateral support provided by braces. As part of an on-going research program, some of these braces were instrumented with strain gauges. The deep soil mixed wall was approximately 300 feet long and 65 feet deep on either side of the truck tunnel. Approximately 34,000 sf of deep soil mixed wall, 90,000 sf of conventional excavation support, 200 braces, and 320 tiebacks were installed. This paper describes the large scope and breadth of the project that required a variety of excavation support techniques. A few of the challenges in designing and installing the support of excavation are discussed. This paper also presents the results of the instrumentation program conducted on the deep soil mixed wall, which stood open for more than a year.

Jan 1, 2006

By Nicholas P. Gura

This paper presents the analysis, design, and load test program results for drilled shafts to support a 70-story hotel tower and associated 10 story podium structures located in Las Vegas, Nevada. A mat foundation for the structure, although feasible, would have produced undesirable differential settlements within the high rise tower footprint and at the interface with adjacent lower level podium structures. The resulting foundation system solution for the 70-story, approximately 800-foot long hotel tower was four-foot diameter drilled shafts, extending 100 below shaft cutoff. The design compression capacity for the four foot diameter drilled shaft was 5,000 kips. The load test program proved that the unique Las Vegas valley geology lends itself to efficient installation, precluding the need for engineered slurry or casing. The load testing program included the installation of two four-foot diameter test shafts to 100 feet below theoretical cutoff and the performance of two highly instrumented independent Osterberg load cell tests with maximum sustained test loads of 12,000 kips. Sonic caliper testing was also performed to document actual in-place shaft diameters and verticality. The load test program also provided information necessary for the foundation design of the podium structures. In addition to the tower?s drilled shaft load test program data, continuous flight auger (CFA) pile evaluation and testing was also performed. The CFA testing consisted of traditional ?top down? loading techniques and was performed as an alternative to the recommended shallow drilled shafts for the lower level podium structures. The results of the CFA test program provided supplemental, insightful soil friction data which was used in conjunction with the drilled shaft test program data in evaluating the most appropriate support for the lower level structures.

Jan 1, 2007

By Mark Spence, Tom Lardner, Matthew Janes

"IntroductionThe design-build method streamlines project delivery through a single contract between the Contract manager and the design-build team. The design-build method places emphasis on collaborative project management between design and construction disciplines to minimize project schedule, reduce costs, encourage balance risk amongst the design-build team. Since 1985, the percentage of nonresidential design and construction projects has increased from 5% to 45%.1A project carried out in Edmonton, Alberta, Canada will be used as an example to illustrate the challenges of the design-build project delivery method and the merits of establishing a GBR. The project involved a complex slope stabilization as part of an extensive freeway widening. At the project location the roadway was being widened within the base of a historic stream valley into a steep slope with a history of a previous slope failure. The slope was to be steepened through the installation of a series of 14 interlocking arc structures constructed half way up the slope. Access and schedule proved critical to the successful completion of the project.Geotechnique and Site HistoryThe geotechnical investigation undertaken for the site included six boreholes drilled at the crest of the slope to depths ranging from 14.5 m to 30.2 m. Laboratory testing of the soil samples included direct shear tests, Atterberg limits and grain size analysis. The geotechnical report also referenced a previous geotechnical investigation that was carried out in response to a failure of the slope in 1971."

Jan 1, 2015

By Yogesh Prashar

Three conventional uplift tests and 12 Rapid Pile Load Tests (RLT) were performed on total of fifteen 16-inch square pre-cast concrete driven piles at a test site in Emeryville California in December of 2000. The uplift tests were performed in accordance with ASTM standards, and the RLTs were performed using a FUNDEX RLT. The RLT is carried out by dropping a mass of 25-tons on top of the pile, thereby inducing a force that is measured by a load cell. An optical lens records the vertical deflection of LED's that are mounted on the pile. Ultimate uplift and compression capacities of each of the fifteen piles were determined using the Davisson method. Soil parameters were calibrated by back-calculation (cohesion and internal angle of friction) using both the results of conventional uplift load versus deflection curve, as well as the results of the triaxial compression tests. A two-dimensional finite difference model including soil elements, and structural elements representing the test pile was setup using the computer program Fast Lagrangian Analysis of Continua (FLAC). FLAC was used to simulate both the uplift as well as the RLT. Strength increase of cohesive material was also accounted for in the analysis. Numerically simulated and theoretically computed pile capacity curves and axial deformation variation with applied load curves are in close agreement to the observed curve during the field test. Conclusions are made from this test site regarding the factors influencing results of RLT.

Jan 1, 2002

By Vincent Joannes, Marine Lasne, Luca Brenelli, Colin Serridge, Inge van Baardwijk, Martin Stanley, Anthony Fisher, Mary Ellen Bruce, Tony Suckling, Pedro Avellanosa

"Abstract The European Federation of Foundation Contractors (EFFC) and Deep Foundations Institute (DFI) developed a sector-specific carbon accounting methodology and associated “carbon calculator” for foundations and geotechnical works. The EFFC-DFI Carbon Calculator is believed to be one of the construction industry’s first collaboratively produced carbon calculator tools for European and international countries based on verifiable and standardized data. It is intended that the tool be adopted internationally and become the open-source industry standard for ground works. A detailed methodological guide is provided with the calculator (Lemaignan and Wilmotte, 2013). This guide explains the background of the standards, accounting methodologies, emission sources and factors that were used as the bases for the tool development and includes detailed guidance on use of the calculator.Drivers for DevelopmentFoundation contractors anticipate project cost and carbon emissions will become inextricably linked in response to the climbing price of fossil fuels and carbon intensive materials as resources become scarce. Low carbon solutions will therefore become more competitive options. Also with high profile construction projects having low carbon/carbon neutrality as requirements, sustainability in the foundations industry also becomes a market issue.This carbon calculator will be used to lead the industry and shape the expectations of commissioning organisations by providing insight into the carbon cost of their projects. Commissioning organizations are encouraged to be aware of the carbon impact of projects and to also facilitate a fair and accurate way of comparing footprints to provide a level playing field for foundation contractors."

Jan 1, 2014

By M. Hesham El Naggar, Yasser Abdelghany

"ABSTRACT: The axial and lateral monotonic and cyclic behavior of helical pile foundations was investigated and new innovative helical screw systems suitable for seismic loadings were developed and patented. More than one hundred full scale field load tests were conducted on instrumented helical screw piles installed in cohesive soil. The piles included: plain helical screw piles (P-HSP); grouted (G-HSPs); fiber reinforced polymer FRP-G-HSPs; and reinforced grouted RG-HSPs. The RG-HSP piles axial capacity was more than twice that for P-HSP, with minimal reduction after cyclic loading, and their lateral capacity was more than 3 times the P-HSPs capacity. A 3-D finite element model was established. The results of 3-D finite element modeling were used to establish the load transfer mechanism and a design methodology for the considered piles.INTRODUCTION AND LITERATURE REVIEWHelical (screw) anchors have been utilized in tension loading and have gained popularity for bearing load applications. Helical piles represent an overall cost effective alternative to conventional piles for new construction and repair applications. The helical piles speed and ease of installation, less noise during installation added advantage with regards to their efficiency and reliability for underpinning including re-support and reconstruction of distressed and damaged foundations for either stabilization or rehabilitation. The “square shaft” SS175 pile is a segmented deep foundation system with helical steel bearing plates (helices) welded to a central steel shaft. Load is transferred from the shaft to the surrounding soil through these bearing plates. Segments or sections are joined with bolted couplings. Practically installed depth is limited only by soil resistance and economics. A helical bearing plate or helix is one pitch of a screw thread. All helices regardless of their diameter have a standard 75 mm pitch (Figure.1). The performance of single helical anchors and group action were studied experimentally and theoretically by several researchers, the researches focuses on the installation torque and uplift resistance. Some researches focus on the load carrying capacity with little pile response to cyclic loading effects or to instrumented full scale field testing. Helical piles axial compressive or lateral loading still is not well characterized and needs more analyses and their seismic performance was not investigated. For such this research was initiated to investigate the helical piles monotonic and cyclic performances under axial and lateral loadings to consider their usage in different applications in seismic zones. Among the several researchers, Clemence (1983); Mooney et al. (1985) conducted field and laboratory testing; Hoyt (1989), Hoyt et al. (1995), and Ghaly and Clemence (1998) conducted theoretical and experimental testing, Puri and Vijay (1984), Huang et al. (1995), Perko (2000), and Pack (2000) conducted theoretical analyses. Rao and Prasad (1993), Prasad and Rao (1994), conducted experimental testing; Vickars and Clemence (2000) studied the performance of helical piles with grouted shafts."

Jan 1, 2014

By W. L. Chong

For a project located in Docklands Victoria, a high-rise development was proposed where the geology comprised soils of various compositions and consistencies to approximately 50m deep before being underlain by a siltstone bedrock. Due to the structural loads and spatial constraints, the majority of the foundation piles were designed to be socketed into the siltstone. Key factors in selecting the Continuous Flight Auger (CFA) technique as an effective piling solution are explained. These factors included structural and geological considerations, piling rig capabilities, pile testing regime to verify load performance and integrity, the extensive suite of construction quality controls and instrumentation records required while also achieving an appropriate piling budget and program. This paper also described how these factors underpinned the design approach of the final piling scheme. Critical aspects considered during construction and post-construction quality and pile testing records required to meet and satisfy the strict project piling specifications are also presented. The project adopted what may be considered the “best practice” in deep CFA piling. To the author’s knowledge, this project achieved the record for the deepest CFA piles in Australia where multiple piles to 53.8m deep were constructed.

Nov 1, 2022

By Lance A. Roberts

Expansive soil formations can be found throughout the United States. When subjected to wetting, these formations have the potential to swell and exert large uplift forces on buildings and foundations. Lightly loaded structures, such as single family residences founded in areas of expansive soils, can be significantly damaged due to uplift movement from swelling actions. Designing an economical deep foundation that can resist uplift forces is critical to prevent damage to these structures. The current solutions to control uplift due to swelling soils, such as over-excavation and replacement of the expansive material or the use of drilled shafts can be costly. Piles made from recycled polymer materials could provide a solution. Due to a lower coefficient of friction along the interface of the soil-pile interface compared to traditional pile materials, solid recycled plastic piles can allow expansive soils to move nearly independently from the pile when wetted. This results in a much smaller magnitude of uplift force being transferred to the structure, which minimizes the risk of significant structural damage from excessive movements. This paper presents the results of research conducted on the use of recycled plastic piles in an expansive shale environment. The preliminary phase of the project involved the installation of six recycled plastic piles at a test site on the South Dakota School of Mines and Technology campus. Two of the piles were subjected to a full-scale compression load test in order to determine ultimate capacity. The remaining four piles were subjected to long-term monitoring of uplift movement during the course of the project. A concrete anchor was also installed at the test site for uplift monitoring. Data gathered during the field and laboratory testing was utilized in a non-linear soil-structure interaction model to predict the displacement behavior and internal stresses within a plastic pile and concrete anchor subjected to uplift forces from the swelling shale. While more research is needed to further understand the application for recycled plastic piles, the results from this research indicate that their use is a viable alternative for support of lightly loaded structures in expansive soil environments.

Jan 1, 2010

By John Lemke

Current practice for monitoring static pile load tests commonly consists of measuring load and displacement at the top of a pile. This is typically accomplished by monitoring dial gauge movements, line pressure of a hydraulic jacking system, and electronic load cells on occasion. While this testing approach provides useful information for one boundary condition (the top of the pile), a system that measures movement and/or strain along the entire length of the pile can provide additional useful data that can be used to refine pile design. Automated data acquisition systems provide the essential ingredient that can integrate these types of sophisticated instrumentation devices into a standard pile load test program in a cost effective way. This paper provides a general overview of pile testing instrumentation and describes a newly developed chain of instrumentation modules that can be embedded in a pile to gather additional testing information. The new system can measure forces and movements within the test pile synchronously with measurements at the pile top, and the direct application of this system to axial and lateral pile testing is illustrated. This is particularly relevant to the design of ACIP and drilled displacement piles since determination of the reinforcement cage length is important from the standpoint of both seismic design and foundation cost.

Jan 1, 2002

By Andrew Peterson

The Maine Department of Transportation offered this challenging design-build project for a new, 12-span, bridge over the Kennebec River in Bath, Maine. This structure would be built to replace the existing Carlton Bridge connecting the village of Bath, Maine to neighboring Woolwich, Maine. The design build team of Flatiron Structures, Inc., and Figg Engineers, Inc., elected to design and build a segmental concrete bridge. Site conditions dictated that this bridge would be supported primarily on deep foundations. Case Foundation Company joined the project team in the winter of 1997 to install twenty-two, eight foot diameter drilled shafts. The drilled shafts were designed with 8' diameter, permanently cased shaft sections and 7.5' diameter rock sockets. Shaft lengths ranged from 20' long near the river's edge to 100' deep in the middle of the river. Rock socket lengths ranged from 12' to 30' deep. Two Osterberg Cell load tests were conducted on production drilled shafts. Figg Engineers utilized the results of the load tests to "fine-tune" the rock socket design during construction of the drilled shafts. Construction of the drilled shafts proved to be very challenging and called on every member of the design-build team to work together throughout the project. One of the most challenging aspects of this project was in the installation of the 8' diameter permanent casing and drilling of the rock sockets. Early in the project, it became apparent that the top of bedrock was broken and unstable. This condition limited the advancement of the permanent casing and the affect of a "seal" at the top of rock socket. As a result, as the rock socket was advanced, loose material spilled into the hole and stopped progress of the socket. In order to resolve this problem, the design-build team developed a redesigned drilled shaft which included the installation of a steel sleeve to seal off the unstable rock formation. Following installation of the sleeve, the rock socket diameter was reduced to 7' diameter and advanced additional length to achieve required design capacity. All drilled shafts were installed with equipment supported on floating barges. Water access, along with the long shaft lengths and very hard bedrock required the use of cranes and drilling equipment that far exceeded the requirements of typical drilled shaft projects. This paper will discuss the relationship between design, construction, and equipment utilization on this challenging design-build project. [ ]

Jan 1, 1999

By Saba Mohan

This study presents results based on the Pile Installation Demonstration Project (PIDP) that was conducted as a part of the East Span San Francisco-Oakland Bay Bridge Seismic Safety Project. For the three full-scale pile installations, two different high-energy hydraulic hammers were selected for the installation. However, these hammers may not have sufficient energy to drive these large diameter piles at their ultimate capacity following long-term set-up. Nevertheless, these hammers were selected because, soil plug behavior, the generation of excess pore pressures and remolding of soil during driving were expected to reduce the shaft and end bearing resistance, and therefore reduce the energy required to drive these piles to design penetration. Data collected during continuous installation driving and after a series of re-strikes at different set-up times ranging from 1 to 33 days were used as input data for CAPWAP. These results were used to estimate the soil resistance along the pile length and at the toe of the pile, and the soil pile set-up behavior. Validity of the procedures used to predict the soil resistance to driving and predicted blow counts were verified with the field observed blow counts and the energy that was delivered to the pile. Based on combined CAPWAP analyses, the soil pile set-up with time was estimated and compared with results of other methods currently available in the literature for predicting the soil pile set-up rate.

Jan 1, 2002

By H. F. Cowie

Britain's first pressurised water reactor (PWR) Nuclear Power Station is now under construction at Sizewell on the Suffolk coast. A linear cut-off wall was proposed to ensure that the drawdown of water to some 14m below sea level in the overlying sands during construction of the new power station would not affect the existing adjacent nuclear power station. The low permeability cut-off wall was constructed by diaphragm walling techniques by excavating a continuous deep trench supported by bentonite mud and then dis­placing the bentonite by a plastic concrete to form the "impermeable" membrane. The paper describes the automated digging apparatus ("Hydrofraise") with the extensive support facilities required to achieve completion within programme, control methods used to obtain the high vertical tolerances and the properties of the plastic concrete and the production plant used for its production.

Jan 1, 1989

By Charles G. Crans, Naresh Gurpersaud

"Toronto’s Union Station, a National Historic Site occupying an entire city block, is the busiest commuter rail transportation hub in Canada. An extensive project is being undertaken to revitalize Union Station while maintaining the historical significance of the building and minimizing disruption to commuters. A significant stage of the revitalization involves excavation indoors, to a depth of up to 5.5 m below the existing floor level to create space for a new transit concourse and a new lower-level pedestrian retail concourse. A hybrid excavation support system utilizing micropiles as soldier piles was constructed over an 18 month period between 2010 and 2011.Development and testing of connections between the micropiles, shotcrete facing, lagging, walers, and tiebacks presented significant challenges. The existing viaduct structure was constructed in the 1920’s on land reclaimed from Toronto Harbour, so there was significant (and ongoing) uncertainty with respect to buried obstructions including relic timber wharfs and abandoned steel and timber piles. Collectively all these conditions precluded the use of conventional methodology; new techniques, installed using modified equipment, and for the first time in the Greater Toronto Area, were required.Details of the existing site conditions, installation challenges, design, construction and performance of the hybrid excavation support system inside this historic structure are presented.INTRODUCTIONUnion Station in Toronto, Ontario is the busiest passenger rail facility in Canada, with 65 million passengers annually and an average of 200,000 passengers each day. Construction of the station was completed in 1920. It has been designated a National Historic Site of Canada and inducted into the North America Railway Hall of Fame in the Facility and Structure category.The Union Station Revitalization Project (USRP) was tendered in 2010 and awarded as a 6-year, $450M construction management / trade contract package. Included was a large scale grade reduction, referred to as “The Dig Down”, to create two basement levels and this required extensive excavation support constructed entirely indoors within the active station setting."

Jan 1, 2017

By M. Dondelinger

This paper presents a comprehensive review of steel sheet piling including internationally manufactured hot rolled sections, their history, applications, installation and driving techniques. The discussion will cover both temporary and permanent installations; temporary piling used in construction of cofferdams with various bracing systems, deep foundation installations for buildings, bridges and tunnels, etc., and permanent piling used for highway, railroad and bridge construction as well as for riverbanks, piers, wharfs and docks, normally required for port facilities. In addition, cofferdams, as self-supporting gravity structures where interlock strength is of prime importance, will be discussed. The design and application of light, intermediate and heavy sections will be presented including heavy combined walls and information on Z-shaped, U-shaped and HZ sections and their corresponding interlocks. Emphasis is placed on new developments for design applications for deep foundations and waterfront structures within the "state of the art".

Jan 1, 2010

By Michael Forrest, John Roadifer, Glen Gorski

"The Calaveras Dam Replacement Project (CDRP) requires large disposal sites to store excess excavated materials that could not be utilized for dam construction. Because of access restrictions during design, the disposal site rockfill toe dike area at the edge of the reservoir could not be explored to evaluate soil conditions. As such, the site had to be explored as part of the construction contract. Exploration revealed very soft clay and loose silty sand up to 40 feet thick that would not be able to support the rockfill dike at the toe of a large disposal site fill. Several alternatives were evaluated to stabilize these soils. Based on constructability, cost and risk considerations, cement deep soil mixing (CDSM) was selected as the preferred method of soil stabilization. The challenge was to design and construct the CDSM stabilization to minimize construction delays. A joint effort by the design engineer, construction manager and contractor achieved CDSM stabilization in about three months, from design through completion of construction. A rigorous quality control program included compression testing of both wet grab and cored soil cement samples to demonstrate that specified strength requirements were being achieved.INTRODUCTIONDisposal Site 3 (Figure 1) is one of the primary CDRP disposal sites having a height of 240 feet and a storage capacity of about 2,500,000 cubic yards. An approximately 40-foot-high rockfill dike at the base of the disposal site provides an erosion resistant toe for the disposal site. The rectangular foundation area shown in red was not able to be investigated during design because of access restrictions."

Jan 1, 2015

By George Filz, Morales, Carlos, Bertero, Filippo Maria, Alessandro, Leoni

"The Deep Mixing Method (DMM) represents a viable solution to improve adverse geotechnical properties of foundation soils for many practical applications. A pre-construction soil investigation campaign is necessary to assess soil properties and to retrieve samples of different soil layers for a laboratory Bench Scale Testing program (BST). The BST has to be designed using various binder types, binder contents, and water/cement ratios in each of the soil types. Following the laboratory program, a full scale Field Test (FT) is typically necessary to verify the results of the BST. This paper will highlight the differences and the importance of performing both pre-construction laboratory tests and field tests to ascertain the proper mixing parameters in the different soil layers. Comparative analyses and interpretations between the lab and field stages, along with accumulated information about soil properties and quality control (QC) results, allow fine-tuning the production parameters throughout a project. Three Deep Mixing Method projects, where both laboratory and field tests were executed, are illustrated: (1) The LPV 111 Project (New Orleans, LA, USA): DMM was used for ground improvement/foundation strengthening to stabilize and support the burden of a new levee raise; (2) The Rio Puerto Nuevo Project (San Juan, PR, USA): DMM was applied to improve the soils adjacent to a 90"" forced sewer main relocation and to improve the soils for the base of a new drainage channel; and (3) State Road 83 (US 331) over Choctawhatchee Bay project (Walton County, FL, USA): DMM was applied to stabilize the causeway sections of the bridge enhancement project. Data recorded during laboratory and field tests for these projects were analyzed and interpreted to select the most appropriate construction parameters to provide a final high-quality product.INTRODUCTIONThe Deep Mixing Method (DMM) represents a viable solution to improve adverse geotechnical properties of foundation soils in many situations. The effectiveness of working parameters depends largely on the physical and mechanical properties of the soil to be treated. Therefore, well designed laboratory and field test programs, aimed to disclose the interaction between the site-specific soils and the mixing parameters, are essential to achieve the desired end product.Generally a pre-construction soil investigation campaign has to be performed to assess soil properties and to retrieve samples of different soil layers for the laboratory Bench Scale Testing programme (BST). The BST has to be designed using various binder types, binder contents (or cement factors - CF), and grout water/cement ratios (W/C) in each of the soil types; the selection of the different combinations and dosages for the BST is based on past extensive experiences on similar materials. Following the laboratory programme results, a full scale Field Test (FT) has to be designed and executed, installing several DMM elements to verify the results of the BST and fine tune the construction parameters, with the appropriate binder type and dosage and the most effective equipment and tool configuration."

Jan 1, 2015

By Sunil S. Basarkar, Dilip M. Dewaikar, Rajesh H. Gajjar

"A load transfer program AXPILE was developed for simulation of the loadmovement characteristics of socketed piles of the Mumbai reg ion. This program used empirical relationships for ultimate shaft resistance at pile-rock interface recommended by Zhang and Einstein (1998). According to their recommendation, ultimate shaft resistance at pile-rock interface is related to the square-root of uniaxial compressive strength of intact socket material by a parameter C, which ranges from 0.4 for smooth sockets to 0.8 for rough sockets. Results of three instrumented pile load tests were compared with the AXPILE generated results. The comparison of analytical and field estimates of the unit shaft resistance confirm the recommendations of Zhang and Einstein (1998) on the unit side shear parameter c,, which was found to be in the range of 0.35 to 0.67.INTRODUCTIONInstrumented pile load tests were carried out on the test piles at the Bandra-Worli sea link project in Mumbai city of western India. High capacity socketed piles were required to take up loads from the superstructure. Hence, in addition to the available toe resistance, an accurate measurement of the shaft resistance in socket portion was desired. The instrumented load tests incorporated Osterbergcell (0-cell) assisted by strain gauge instrumentation to estimate the shaft resistance mobilization in the socket portion.AXPILE load transfer program was developed for load-movement simulation of socketed piles (Basarkar, 2004). The load transfer algorithm based on Coyle and Reese (1966) was incorporated in this program, which used empirical correlations and functions to account for load transfer in piles through shaft and toe resistance.This paper compares the computed unit shaft resistance from the AXPILE program with the measured values recorded from the instrumented pile load test."

Jan 1, 2005

By Thomas Lardner

Excavation for The Bow, EnCana, in downtown Calgary, occurred between May 2007 and September 2008. A monitoring programme was used to determine the behaviour of the shoring wall, soil and bedrock during the excavation for the 21 metre (69 ft) deep excavation with a footprint of approximately 17,000 m2 (183,000 sq ft). Results from the inclinometer readings indicated that significant horizontal movement due to a weak rock layer and shear band effect. These modes of movement account for up to 100 mm (4.0 in) and 45 mm (1.8 in) of lateral deflection, respectively. Based upon the results of the monitoring programme, rock samples were collected from the weak mudstone bedrock, with great difficulty, to determine the strength and deformation parameters. Results from the uniaxial compression tests indicate a UCS around 830 kPa (120 psi) and elastic modulus between 80 and 180 MPa (11 and 26 ksi). Mohr-Columb parameters were determined to be c' = 340 kPa (49 psi) and f' = 24°. Residual strengths were determined to be c'r = 0 and f'r = 15°. Using the results of the laboratory tests and field investigation records, an initial finite element analysis was conducted. Results of the analysis show good correlation when compared with the observed monitoring deformation, indicating accurate portrayal of rock parameters. Additional analysis and investigation is required to determine the principal horizontal stresses in magnitude and direction.

Jan 1, 2010