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By James P. Hambleton, Anastasia Nally

This work focuses on the numerical simulation of multi-plate anchor systems (e.g., helical anchors) in sand subjected to vertical loading. In assessing the stiffness and capacity of these multi-plate anchor systems, full awareness of the abilities and limitations of the various analysis methods must be understood. This work first summarizes studies completed by others and then goes on to assess the failure mechanisms of multi-plate anchors in sand and the influence of (1) plate width-to-depth ratio, (2) number of plates, and (3) relative positioning of plates. The analysis makes use of (1) conventional limit analysis, (2) so-called modified limit analysis that employs reduced strength parameters to account for the influence of soil dilatancy, and (3) the displacement-based finite element method, which considers elastic as well as plastic deformation leading to failure. The work critically reflects on limitations in the current analysis methods for helical ground anchors. INTRODUCTION Helical anchors are a relatively low cost foundation type, typically consisting of a steel rod and single or multiple plate attachments. In recent decades, they have seen rapid growth, and as outlined by Merifield and Sloan (2006) and Hambleton et al. (2014). Design techniques for helical anchors have previously been predominately empirical, as much of the past research in this field is experimentally based. It is common practice for helical anchors to be modeled as horizontally oriented plate anchors in both numerical and experimental analysis. This work focuses on analysis based on the finite element method, including so-called finite element limit analysis and the conventional displacement-based finite element method, with some comparisons made to experimental studies. Numerical simulation of anchor pull-out capacity in cohesionless soils is stunted by the many difficulties faced when using numerical analysis with cohesionless soils. Additional variations can be seen when comparing the serviceability based load capacities to the ultimate load. In this work, both the force-displacement response (stiffness) and the ultimate anchor capacity are assessed, with more focus on the latter. This work focuses only on analysis techniques for multi-plate anchors with vertical loading in cohesionless soils. Many studies have been completed in this area, some of which assume a rectangular plate in a plain strain model (Rowe & Davis, 1982; Merifield & Sloan, 2006; Cerfontaine et al., 2019). Whereas others use axisymmetric conditions (Baker and Kondner, 1966; Saeedy, 1987; Murray & Geddes, 1987; Ghaly & Hanna, 1994; Sakai & Tanaka, 1998; Merifield et al., 2006;) and minimal studies considered both axisymmetric and plane strain in the one study (Vesic, 1971; Tagaya et al., 1988; Murray & Geddes, 1987; Sarac, 1989).

Jan 1, 2019

By Chunli Wei, Mark Jen, Xiaojun Wang

"After more than 85 years of service, a critical link between New York and New Jersey, the Goethals Bridge over the Arthur Kill waterway, is being replaced with two new parallel bridges. Each bridge includes 1,650 feet long signature steel composite cable-stayed bridge, a 2,789 feet long New York approach and a 1,889 feet long New Jersey approach. The superstructure of each approach is supported on a series of two-column concrete piers and each column is supported on a single large diameter drilled shaft varying from 4.5 to 9 feet in diameter and anchored 45 feet below ground into the underlying rock.A performance-based methodology was followed for the strength and extreme event limit states design of the drilled shaft foundations. The design for seismic loads has been performed using the AASHTO Guide Specifications for LRFD Seismic Bridge Design. For all strength and service loads, the AASHTO LRFD Bridge Design Specifications were used. Since the longitudinal and confinement requirements in the two specifications vary, the minimum longitudinal reinforcement was based on the more stringent requirements of the two codes. A design example is presented to illustrate the methodology in bridge deep foundation design using nonlinear time-history global analysis results with soil-pile interaction represented by sets of horizontal and vertical nonlinear soil springs along the drilled shaft, based on the soil and rock properties from the boreholes test results. In this paper the design methodology implements strain limits related to earthquake intensities and damage levels to calculate the capacity using XTRACT analysis, which aids designers to adopt applicable provisions that meet specific design requirements.INTRODUCTIONAfter more than 85 years of service, a critical link between New York and New Jersey, the Goethals Bridge over the Arthur Kill waterway, is being replaced with two new parallel bridges designed to carry vehicular traffic and a future mass transit corridor. They include two 1,650 feet long signature steel composite cablestayed bridges with 260 feet tall V-shaped concrete gateway towers (Figure 1). The approaches consist of continuous pre-stressed concrete girders. The New York approach is a single structure consisting of 18 continuous spans, sloping at 4% for a total length of 2,789 feet without expansion joints. Similarly, the longest continuous portion on the New Jersey approach, with a similar slope, consists of 11 spans for a total length of 1,889 feet without expansion joints. The superstructure of each approach is supported on a series of two-column concrete piers that vary in height from 121.3 feet near the cable-stayed bridges to 11.8 feet near the abutments. Each column is supported on a single large diameter drilled shaft varying from 4.5 to 9 feet in diameter and anchored 45 feet below ground into the underlying rock."

Jan 1, 2016

By Liiban A. Affi

The most difficult task of designing multilevel tieback walls for deep excavation support is the determination of lateral stresses. These lateral stresses act not only on the shored height, but also on the embedded portion of the soldier pile, all the way down to the pile tip. Examples of lateral stresses include uniform surcharge load (soil spoils or equipment), strip load surcharge from Cooper E80 (train loads), line load surcharge (exterior footing or retaining walls), and point loads (cell tower). In this paper we will discuss the various surcharges, do step by step example calculations and show how to take the total lateral stress output and present the design pressures for direct use by the substructural designer. Included is a case study from a project Anaheim Hills, California, USA.

Jan 1, 2010

By Rachael M. Fischer, Daniel J. Woeste, Terence P. Holman

"A new 50 MW biomass renewable energy power plant was planned for construction in southwestern Georgia. The original foundation design consisted of very conservatively designed H-pile groups with vertical and battered piles to carry the axial and lateral loads. The authors conducted a testing program to value-engineer the foundations with the goals of increasing the working axial pile resistance and reducing or eliminating battered piles. Seven test piles were installed and dynamically monitored with a Pile Driving Analyzer (PDA). Two lateral load tests and one tension load test were conducted. The results of our testing program allowed the project team to: (i) increase working pile resistances by factors of 1.5 to 2, reducing the total number of piles by more than 30%, (ii) eliminate the battered piles, and (iii) lessen overall project risk. Poor communication and documentation in a critical area of the site required some piles to be spliced and re-driven after additional PDA testing, establishment of new driving criteria, and consideration of longterm soil setup. This case study emphasizes the economic and risk reduction benefits of a design phase testing program, and the need for consistent communication between parties in the field.INTRODUCTIONA new 50 MW biomass renewable energy power plant (Plant) was planned and constructed in southwestern Georgia. The Plant converts clean wood-based and paper-based waste from existing forestry and pulp operations, waste timber, and maintenance operations into steam that is used by an adjacent manufacturing facility. The Plant also generates electric power with limited greenhouse or particulate emissions for use by a local utility provider.The project site (Site) is located in Dougherty County, in the Coastal Plain physiographic province of Georgia; an area of known karstic activity. Specifically, the Site is underlain at depths of 30 to 45 ft by the Ocala Formation, a light-colored fossiliferous limestone of the Eocene era. According to Watson (1981), the Ocala Formation is 125 to 200 ft thick in the vicinity of the Site and increases in thickness to the southeast. Due to differential weathering, this formation is characterized by an irregular upper surface that transitions from sandy clay/clayey sand into a dense to very dense silt and fine sand locally referred to as limestone. This subsurface stratum is most relevant to the foundation design of the Plant."

Jan 1, 2016

By Lawrence F. Johnsen, Felix Ferrer, Dino Tomasetti, Cassandra A. Wetzel

"A 17 story building was constructed at the Brooklyn Navy Yard on a site with a long history of development. Most recently the site supported a dewatering well and craneway to service two adjacent drydocks. The subsurface conditions generally consist of the following strata and approximate depths: miscellaneous fill and debris to 20 ft., organic soils to 35 ft., liquefiable sand to 45 ft., varved clay to 65 ft., glacial till to 95 ft. and gneiss bedrock.Hollow core bar piles replaced 18 in. diameter caissons on a 1.67:1 basis. The resulting service loads on the hollow bar piles were 600 kips compression, 21 kips lateral, 180 kips tension and 450 inch-kips moment. The top 30 feet of the hollow bar was cased with a 16 in. x 0.375 in. Grade 50 steel pipe. The piles were socketed 6 feet into bedrock. An extensive load testing program confirmed the axial and lateral load capacities. The paper will also discuss some adjustments to the installation procedure based on the load test program.PROJECTThe hollow bar piles were installed to support a 95,000 sf footprint, 17-story office building at the Brooklyn Navy Yard. The Brooklyn Navy Yard was first developed in the late 1700’s to build merchant vessels. The federal government purchased the old docks and adjoining 40 acres in 1801. The site was an active U. S. Naval Shipyard from 1806 to its decommissioning in 1966. At its peak in World War II it employed 70,000 people, 24 hours a day. Since 1966 the property has been converted to private manufacturing and commercial activity.The site is located between Dry Docks 2 and 3. The adjacent drydocks extend 40 to 43 feet below grade. The drydock walls are restrained by tierods extending back to deadman anchors. The site is also underlain by piles that were installed to support rail lines and a craneway. The building footprint also covered an 85 ft. wide, 70 ft. deep dewatering well which had a thick slab. The structural engineer for the project, ARUP, designed the building to span over the dewatering well.SUBSURFACE CONDITIONSIn September 2014, Langan Engineering conducted a geotechnical engineering study for the project. Figure 1 provides a subsurface profile through the long axis of the site. The general soil profile was very erratic but generally consisted of miscellaneous fill and debris to 20 ft., organic soils to 35 ft., liquefiable sand to 45 ft., varved clay to 65 ft., glacial till to 95 ft. and gneiss bedrock. The fill contained numerous obstructions from the over 200 years of site development. The organic soils were mostly very weak and compressible organic silt. The depths and thicknesses of the varved clay, and sand varied"

Jan 1, 2017

By Brandon T. Buschmeier, Sonia S. Swift, Michael P. Walker, Frederic Masse

"Ground improvement has undoubtedly become a cost-efficient and effective solution to support the development of poor soil sites. Ground improvement elements, such as Controlled Modulus Columns (CMCs), replace piles by improving the subsurface soils and reducing settlement. As ground improvement becomes more popular, the applications become more creative and ground improvement is being used to control settlements under large structures with tight settlement tolerances.In this paper, we will discuss the use of CMCs to support two (2) large industrial warehouses where soil conditions would normally lead to the use of deep foundations and a structural slab, grade beams, and hung utilities to prevent excess settlement. Each of the sites we will discuss had poor soil conditions in the form of very soft or compressible soil, heterogeneous fill of varying thickness, and environmental contamination. At each site, we developed a design that would allow for the use of Controlled Modulus Columns (CMCs) with a Load Transfer Platform (LTP) in place of the previously-proposed deep foundations. The use of the CMCs also allowed for the use of spread footings and slab on grade construction. The benefits of this value-engineering approach include economy in the foundation system, risk mitigation by not disturbing contaminated soils requiring expensive removal, and ease of access for future sub-slab upgrades with new tenants. Additionally, the use of recycled concrete aggregate as an LTP is more environmentally friendly than placing structural slabs with heavy steel reinforcement.Designing for the settlement of large warehouses is challenging because it requires changing how we typically perform our designs. For most structures, the slab loads are relatively light when compared to the footing loads, whereas for warehouses, the slab is heavily loaded compared to the relatively light footing loads. Thus, it becomes essential to perform three-dimensional analyses to confirm that the proposed CMC layout will provide uniform support of the slab and footing across a variety of loading scenarios (loaded bays vs unloaded or travel bays). The complexity of the designs for these warehouses generated interest in conducting large area load tests over a grid of multiple columns. The performance of the area load tests provided invaluable information on the effectiveness of the LTP and CMC spacing. In this paper, we present a general description of CMC ground improvement, the differences between ground improvement and traditional pile foundations, our typical design methodology for CMC design, and the modifications to that methodology for warehouses."

Jan 1, 2017

By Sanjay Gupta, Sorabh Gupta, Ravi Sundaram, Abraham Varghese

"Geotechnical investigation for the Kochi Metro revealed a critical section of the Viaduct near Ernakulam Junction Railway Station. Four piers, located over a 220 m stretch, were passing through an area with substantial thickness of soft clay. The scope of the geotechnical investigation included two boreholes and a static cone penetration test at each pier location. In the boreholes, field vane shear test was conducted at different depths in addition to the routine SPT. The design of heavily loaded piles in such strata is a challenge due to the liquefaction of the shallow sands and negative skin friction / down-drag in the soft under-consolidated clay. Bored cast-in-situ piles of 1500 mm diameter extending to 50-60 m depth were used to carry 500-600 tonnes load.INTRODUCTIONThe first phase of the rapid transit system at Kochi, Kerala (See Fig. 1) whose elevated route spans from Aluva to Thripunithura covers a total distance of about 25 kilometers. One of the more critical sections of the viaduct exists near the Ernakulam Junction Railway station where the alignment takes a sharp curve to move towards Vyttila, crossing the railway tracks and running partially over the approach of South over-bridge.In this section, four piers located on either side of the railway tracks near the Route Relay Cabin of Ernakulam Junction Railway Station pass through an area with substantial thickness of soft underconsolidated clay.The alignment is geotechincally challenging due to the presence of loose liquefiable sand and soft underconsolidated and sensitive clay.Initial investigations by the owner based on limited boreholes only yielded conservative and inconclusive pile capacities. For a thorough understanding of the soil behaviour, a detailed geotechnical investigation was carried out to assess the engineering behaviour of the soil strata.The scope of the geotechnical investigation included two boreholes and a static cone penetration test at each pier location. In the boreholes, field vane shear tests were conducted at different depths in addition to the routine SPT."

Jan 1, 2015

By R. K. Filip

"Steel bearing piles have long been used to carry high compressive, tensile and lateral loads. Such piles are most commonly tubular or ""H"" profile and are typically installed using percussive techniques. The noise and vibration associated with such installation techniques tends to preclude the use of steel bearing piles in urban and other sensitive areas.This paper describes the design and construction of an innovative new road bridge in Milton Keynes, UK. The steel bearing piles were required to continue out of the ground to form the bridge columns and abutments and then be cast directly into the soffit of the reinforced concrete bridge deck. This project was to be the first time in the UK, that this form of bridge design had been used.The paper shows how new installation techniques allowed the designers to use these high capacity steel elements in a sensitive urban environment without the use of percussive or vibratory installation techniques. Finally the paper shows how these quiet and vibration-less installation techniques can be extended to other applications.A UNIQUE BRIDGE SUPPORTED ON ""BOXED SHEET PILES""CONCEPT HISTORYThere are over 700 bridges in Milton Keynes. Concrete is the dominant construction material, most are single span with massive parallel wing wall retaining abutments. All have a certain uniformity of aesthetic design. Pell Frischmann Consultants Ltd (PFC) proposed to the client, English Partnerships (EP), that an ""integral bridge"" with a slender open appearance would be an appropriate aesthetic form for a new highways bridge, within the district of Westcroft (figure 1). The concept required that the bearing piles be continued up out of the ground to form the bridge columns and abutments. Four rows with four piles in each row were suggested. Each would then be cast directly into the reinforced concrete bridge deck forming a moment connection (figure 2). This concept meant that a single continuous steel structural member would replace traditional reinforced concrete bored piles, pile caps and piers. This member would carry vertical and lateral loads. The conceptual design was intended to meet the following client requirements:"

Jan 1, 2005

By S. P. Mukherjee, Smita Tung

"Piles are generally subjected to uplift in case of under ground and water front structures. Sometimes piles are also to resist uplift loads in transmission towers, dry rock, and so on. Experimental investigations of single piles and pile groups have been carried out using model hollow circular aluminum piles, having 25.4 mm outer diameter and lengths of 600 mm, 750 mm and 900 mm. Pile groups of 2?1 and 2?2 arrangements have been used in the experimental investigations. L/d ratio has been kept equal to 24, 30 and 36 in all the cases. All the single piles and pile groups have been tested under vertical uplift. Spacing between two piles in a group has been varied with respect to pile diameter such that spacing to diameter ratios of pile are 3, 4 and 5 in case of pile groups. An attempt has also been made to analyze those models of single piles and pile groups under vertical uplift by PLAXIS 3D software. Good analogy has been observed between the results of experimental and numerical studies. A parametric study has been carried out to observe the variation of ultimate uplift capacity of pile groups with spacing and depth of embedment. It is observed that for a particular embedment length of pile and a particular group arrangement the ultimate uplift capacity increases with increase of spacing. It is also investigated that for a particular spacing and particular group arrangement, the ultimate uplift capacity increases with increase of embedment depth. Those variations have also been presented with graphs which are generated considering non dimensional forms of parameters. The paper brings out change in pullout capacity of pile groups with spacing and embedment depth of piles.1. INTRODUCTIONPrediction of uplift capacity of single piles and especially of pile groups is one of the most interesting areas of research in geotechnical engineering. Pile foundations are frequently used to transmit the superstructure loads to deeper strata if the subsurface soil is of inadequate strength. The worst possible case may be considered to occur when all the piles in a group subjected to uplift. In cohesionless soils, the shaft resistance is an important source of pile capacity under axial loading, especially when the pile is subjected to uplift loading. Poulos and Davis (1980) recommended estimating the uplift capacity of piles as 2/3 of the downward shaft resistance. Later Ramasamy et al. (2004) indicated that the upward shaft resistance is significantly less than the downward shaft resistance. Some studies were conducted on the behavior of a single pile under uplift loads, such as those by Sowa (1970), Vesic (1970), Das and Seeley (1976), Levacher and Sieffert (1984), Rao and Venkatesh (1985), Chattopadhyay and Pise (1986), and Shanker et al. (2007). Das et al. (1976) conducted a model study to test the uplift capacity of single piles and pile groups buried in sand, and they also determined a relationship between the efficiency of a pile group and its spacing. Chattopadhyay and Pise (1986) proposed an analytical method for predicting the uplift capacity of piles embedded in sand and obtained reasonable agreement between experimental and theoretical results. Gaaver (2013) investigated experimentally that an upward displacement of about 1.4–2.5% of the pile diameter is required to attain the net uplift capacity for both single piles and pile groups. The uplift resistance of pile groups depends on the several variables like group size, shape, spacing to diameter ratio of piles, embedment depth to diameter ratio of piles, soil type and its density and soil-pile friction angle."

Jan 1, 2015

By M. Krzaninski, Y. Zou, A. Frost

The foundation solution for a data centre building in Sydney, Australia comprised two alternatives, the first of which incorporated the use of CFA piles founded in rock at approx. 27m depth to support column working loadings of approx. 7.5MN, and the second utilising rapid impact compaction with a raft foundation of 1.0m thick concrete slab. Soil conditions comprised 1m of fill over 3 to 4m of sands varying from loose to dense consistency, underlain by very stiff clays overlying the rock. A creative solution incorporating Rapid Impact Compaction to improve the loose soils in conjunction with a piled raft solution was proposed. Piles proposed under the raft were Atlas Drilled Displacement piles which offered advantages of displacement pile performance and savings in time and material costs. The piled raft solution was developed in consultation with the consulting structural engineer, combining the skills of the piling contractor and consulting engineer to the benefit of the project. This paper describes the development and design aspects of the piled raft solution adopted for the project.

Nov 1, 2022

By Walter E. Vanderpool

Type 1B micropiles (Bruce and Juran, 1997) can be installed rapidly and efficiently. During an 85-day period, 536 micropiles were installed to depths of 61 meters within a site 41 meters by 43 meters. Their performance, as measured by load test, varied even where the materials, construction procedure, and installation technique were closely monitored and controlled. The variation in displacement, as measured by the standard deviation, exceeded 50 percent of the mean test-load displacement for all loads up to the maximum load applied (2670 kN). This study provides a statistical basis to predict variability with respect to the construction method, micropile materials, and installation technique. The variability of displacement at all test loads is a fundamental characteristic of this type of drilled deep foundation system.

Jan 1, 2002

By Randy R. Williams, Brian W. Wilson, George M. Filz, Marina S. W. Li, Donald A. Bruce

"In-situ wet grab sampling and post-installation coring of soil-cement structures are typically carried out for Quality Control (QC) and Quality Assurance (QA) of deep mixing (DM) schemes. Wet grab sampling and testing is used to provide data to indicate that performance requirements are being met during production, in advance of coring, which typically occurs at 28 days or later, following installation. While unconfined compressive strength (UCS) tests from wet grab samples provide good production indicators, industry practice often requires that acceptance criteria of soil-cement structures be based on UCS results from representative core samples.This paper outlines the approach adopted for field sampling and QA/QC testing carried out in highly variable subsurface conditions at a site located in northern British Columbia (BC), focusing on postinstallation soil-cement coring and strength testing for an extensive deep mixing scheme. A discussion on suitable methods of coring soil-cement structures and appropriate selection of samples for testing that are representative of the in-situ soil-cement structures is provided. This paper also discusses the selection strategy adopted for verification of strength and modulus parameters used for design, providing spatial and time coverage, as well as the acceptance criteria implemented, and provides comparisons with published industry recommendations.BACKGROUNDAn extensive deep mixing ground improvement scheme was completed for the development of a Liquefied Natural Gas (LNG) Facility to be located in Bish Cove, BC, Canada. The deep mixing scheme was implemented to treat very weak native deposits in-situ to support two mechanically stabilized earth (MSE) walls up to 20 m (66 ft) high, and their associated bulk earthworks. Within the DM area, the subsurface conditions were highly variable, ranging from deep (up to 21 m (69 ft) thick) deposits of very soft to soft clayey silt to silty clay, overlying layers of dense to very dense gravelly sand to sand and gravel, to compact deposits of silty sand (up to 15 m (49 ft) thick), overlying dense sand and gravel. Bedrock was encountered beneath the granular deposits and generally comprised granodiorite with occasional andesite dykes."

Jan 1, 2015

By Abdelmalek Bouazza, Aamir Mahawish, Will P. Gates

Bio-grouting by means of microbial induced calcite (calcium carbonate) precipitation (MICP) to improve mechanical properties of granular soils has gained much attention in recent years. The biogrouting process offers an alternative and environmentally friendly approach to conventional soil improvement techniques, such as cement. Bio-grouting by urea hydrolysis has been extensively applied to tackle various geotechnical problems. However, it has yet to be applied to improve engineering properties (compressive strength) of a coarse cohesionless material with the aim using it as sand/stone columns within soft and very soft soils. This paper investigates the effect of using light, moderate and heavy biochemical treatments on the unconfined compressive strength (UCS) of coarse sand columns. In addition, the microstructure of the bio-cemented coarse material has been analysed by X-ray computed tomography (XRCT). The experimental results revealed that the UCS could reach up to 200kPa, 1000kPa and 5500kPa for light, moderate and heavy bio-cemented coarse sand columns, respectively. The microstructure investigations showed that the deposited calcium carbonate can be identified using XRCT imaging and can be associated with the gain in UCS values. Various microstructure properties, such as void ratio, dry density and porosity were also identified and compared with the laboratory data.

Jan 1, 1900

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 Frank Haehnig, Harald Krenn, Harm-Christoph Claassen

"The Wadi Dayqah Dam Water Supply Scheme represents one of the most important projects implemented by the Sultanate of Oman to ensure sustainability of water resources. The principal components of the project comprise two dams to impound the Wadi Dayqah, to store and supply drinking water to the local area and to Muscat, the capital city of the Sultanate.The Main Dam with a central spillway is a RCC Gravity Dam with a maximum height above foundations of 75m, crest length 400m; the Saddle Dam is a rockfill dam with central clay core, max height above foundations is 49m and crest length 360m. During construction of the Saddle Dam a key trench was excavated to 10m depth and filled with compacted clay connected to the central core of the embankment. Grouting utilizing cement grout was performed as a single line grout curtain prior to each filling operations. Both Dams are founded on soft Siltstone, Claystone, Sandstone and inter-bedded harder limestone.After construction of the Saddle Dam, once water was in the reservoir it became evident in early 2010 that some seepage was occurring apparently from the right abutment. This seepage became more marked when the reservoir first filled to discharge over the spillway in June 2010. In order to reduce the seepage, additional sealing works by drilling and grouting of a three row curtain up to 80 meter target depth were initiated to supplement the existing single row curtain. Part of this project for the sealing works has also been to drill additional investigation holes to provide more information and confirm extend of the additional sealing works and its limits.Züblin Ground Engineering was awarded the Additional Sealing Works Contract. Whilst Equipment was on Site, the opportunity was taken to carry out drilling and grouting on the Left Abutment of the Main Dam to reduce seepage through that abutment and to install additional standpipe piezometer for future monitoring of seepage patterns.Work on this Contract started on site in January 2013 and was substantially completed in January 2015.At the time of Tender Züblin Ground Engineering propose and Alternative Design in the form of a Secant PileCut-Off Wall, 85m long to a depth of 40m with additional drilling and grouting below the foot of the cut-off which was then included in the contractual scope."

Jan 1, 2016

By Rakam Lama Tamang, Michael J. Byle, Stephen Ernst

"For various reasons, dredging may become necessary in front of existing bulkhead walls, either for channel deepening or for environmental remediation of contaminated sediments. The removal of sediments at the base of bulkhead walls removes support for the toe of the wall that must be assessed. Evaluation of this impact can be problematic for aging bulkheads for which no design or construction records exist. This paper will address the steps that should be taken in investigation and analysis to assure proper assessment and means to address uncertainties and gaps in information. The steps include pre-investigation data review, field inspection, geotechnical and geophysical investigation tools, parametric analysis and design tools. Examples from several bulkhead assessment projects will be provided that include a variety of conditions and tools for application. The focus of the paper will be on the integration of technologies to assess bulkhead geometry, geotechnical properties and stability, structural safety and constructability issues with removal of support, and means of temporary and permanent stabilization for environmental applications.IntroductionBulkheads and quays have existed as long as there have been waterfront activities. Some of the earliest date back to 1200 B.C.E.(Raban, 1987), however in the United States few predate the eighteenth century. Most extant bulkhead structures, and all steel sheet pile bulkhead walls date from the early 20th century or later. These structures function to protect the shore from erosion, support landside activities, and serve as place to moor and offload vessels. Regardless of the age or usage of existing bulkheads, it is essential to assess and protect them if needed where removal of soils on the water side of the bulkheads is planned to dredging.Waterfront BulkheadsExisting bulkhead structures can be classified into two types: Cantilevered, and anchored. Cantilevered walls are completely supported by the soil on the water side, while anchored bulkheads are supported both by the soil on the water side and anchorage on the land side (Figure 1). Walls may be constructed of timber, steel, or concrete. Timber walls may be lagging with soldier piles, cribbing with soldier piles, or timber sheeted such as Wakefield walls (Figure 2). Steel bulkheads are most commonly constructed using sheet piling comprised of interlocking A or Z shapes, though some historic walls were constructed with flat sheets. Precast concrete sheet piling has also been used in construction of bulkhead walls. Anchorage may be provided by steel bars or tendons attached to deadmen, sheet piling, driven piles, or earth anchors."

Jan 1, 2017

By B. De Paoli

At Pietrafitta, between Assisi and Perugia, ENEL (Italian National Electricity Authority) has for some time been managing a power-station operated with lignite, mined from an open mine on the way to exhaustion. A new plant is under construction which is located in the mine that was filled with tailings, mainly clays, sandy silts, lignite and ashes produced by the power-station. The soil profile is shown in Fig. 1: the thickness of the made ground is around 27 m. The foundation of the new power-station is on 320 t piles, 1.20 m diameter, embedded in the cohesive base formation at a depth of 57.5 m. 2,350 piles will be constructed for a total length of 125 km. It is therefore one of the largest pile sites at present in operation in Italy. [ ]

Jan 1, 1994

By Eric Lindquist, John Compagnone, Gabriel Carvajal

"Condon-Johnson & Associates, Inc. (CJA) with the assistance of design consultant, Brierley Associates, designed and installed a water tight shoring system utilizing several ground improvement techniques jointly. Prior to the installation of the shoring system, a test program consisting of the installation and testing of 7 jet grout columns; 1 soil mix panel; 7 soil anchors and 3 tie downs was performed to verify design assumptions. State-of-the-art quality control measures were employed throughout the project.The shoring system consisted of:•,Deep Soil Mixing (DSM) wall utilizing triple axis tooling to install overlapping columns along the perimeter of the proposed excavation to a treatment depth of 54 feet.•,Installation of steel piles in DSM to provide rigidity to the wall.•,Installation of a jet grout bottom seal, installed from surface to a depth of 58 feet below existing grade.•,Installation of 153 soil anchors, 1-1/4” diameter and 47’-6” length, to tie the jet grout bottom seal to the native soil below to resist hydrostatic uplift, installed from existing grade to a depth of 91 feet.•,Installation of walers and pipe struts for internal bracing•,Installation and stressing of 117 tie downs, 1” diameter and 16 ft length, to tie the pump station mat slab to the jet grout bottom seal, installed from inside the excavated pit.Subsurface conditions at the site consist of uncontrolled fill materials to a depth of 20 feet comprised of sandy silt and clayey sand. The native soils underlying the fill generally consist of soft and compressible lean clay and silt with varying amounts of sands to a depth ranging from approximately 44 to 54 feet below ground surface, which in turn are underlain by dense to very dense silty sand. The groundwater elevation at the site is approximately 8 feet below ground surface.This paper covers the design aspects, construction, and quality control measures undertaken by the geotechnical contractor, with supporting figures.INTRODUCTIONThe owner, County Sanitation District No. 2 of Los Angeles County, designed upgrades to their existing Long Beach Main Pumping Plant Facility. The upgrades consist of a new pump station that includes a reinforced concrete below-grade wet well and dry well, a two-story operations building, two 78-inch diameter pipe inlets, two 42-inch diameter discharge pipelines connecting the existing manifold, two pipe junction structures, two insert-type junction structures, and electrical transformers. This paper focuses on the excavation shoring for the new pump station. The original shoring design concept for the pump station excavation illustrated on the contract plans consisted of pressed in sheet piles, a jet grouted bottom seal with soil anchors, 2 levels of internal bracing, and tie-down anchors to resist hydraulic uplift forces on the buried pump station."

Jan 1, 2017

By Federico Pagliacci

Continuous Flight Auger (CFA) technique represents an important technological advance in the construction of piles in soft soils. The possibility of excavation under the water table with no need for drilling fluids, along with high productivity, have resulted in this technique?s becoming widespread in many countries. However, CFA technology has limitations because of its difficulty in penetrating hard layers and cross strata with cobbles and boulders. In these situations, pile verticality may be an additional problem. The Cased Augered Pile (CAP) technique consists of penetrating the soil with an auger housed in a casing. Two independent rotary heads sliding along the rig mast operate the auger and the casing. By adjusting the height of the casing shoe and auger bit according to soil type, it is possible to drill piles in very severe conditions - in the presence of cobbles and boulders - and to socket the pile into the rock. The use of a steel casing enables improved pile verticality. Therefore, the CAP technique is also used to construct secant piles to be used as diaphragm walls. The limitations of this technology are the depth, usually no more than 27 m (88 feet), and the size of the rig that supports the drilling tool, no less than 70 t (77 short tons) in working conditions. This paper illustrates CAP technology, the drilling system, and the characteristics of concrete and steel reinforcement and offers a case study of the Palermo-Carini second railway line, which used CAP to construct the new 30 km (18.6 mi) railway line, 20 km (12.4 mi) of which passes through the very congested downtown area of Palermo. More than 300,000 m (186.4 mi) of piles have been drilled in dense calcarenite formations with unconfined compressive strength of 15-25 MPa (2,200-3,600 lb/inch2), soft clay, and silt formations.

By Federico Pagliacci

Continuous Flight Auger (CFA) technique represents an important technological advance in the construction of piles in soft soils. The possibility of excavation under the water table with no need for drilling fluids, along with high productivity, have resulted in this technique’s becoming widespread in many countries. However, CFA technology has limitations because of its difficulty in penetrating hard layers and cross strata with cobbles and boulders. In these situations, pile verticality may be an additional problem. The Cased Augered Pile (CAP) technique consists of penetrating the soil with an auger housed in a casing. Two independent rotary heads sliding along the rig mast operate the auger and the casing. By adjusting the height of the casing shoe and auger bit according to soil type, it is possible to drill piles in very severe conditions - in the presence of cobbles and boulders - and to socket the pile into the rock. The use of a steel casing enables improved pile verticality. Therefore, the CAP technique is also used to construct secant piles to be used as diaphragm walls. The limitations of this technology are the depth, usually no more than 27 m (88 feet), and the size of the rig that supports the drilling tool, no less than 70 t (77 short tons) in working conditions. This paper illustrates CAP technology, the drilling system, and the characteristics of concrete and steel reinforcement and offers a case study of the Palermo-Carini second railway line, which used CAP to construct the new 30 km (18.6 mi) railway line, 20 km (12.4 mi) of which passes through the very congested downtown area of Palermo. More than 300,000 m (186.4 mi) of piles have been drilled in dense calcarenite formations with unconfined compressive strength of 15-25 MPa (2,200-3,600 lb/inch2), soft clay,

Jan 1, 2017