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By Y. M. Ha, T. D. Nguyen, D. T. Nguyen, H. K. Choi

Conventionally, cement deep mixing (CDM) columns are designed to have constant diameters over the improved depth as this facilitates the construction procedures. However, this design pattern may be inefficient in cases of spread footings or shallow foundations. This paper first briefly introduces principles of an improved CDM method that can create head-enlarged CDM (termed PF) columns. A simple analysis approach was introduced to obtain optimal shape of PF columns that results in minimum settlement. The effectiveness of this improved method over the conventional CDM method was then illustrated by settlement analysis for an actual footing in a case study using two recommended analytical methods in the literature. Analysis results from the case indicated that by using the same amount of soil-cement mixed volumes, settlement from a footing on PF columns can reduce up to 10 % compared with that from the same footing on CDM columns. In addition, a material quantity comparison for the case indicated that to have the same settlement values the volume of each PF column can be reduced of around 10% compared with that of the CDM column. INTRODUCTION The cement deep mixing (CDM) method is one of the most popular methods in ground improvement works. Details on the method such as construction procedures, necessary equipment and recommendations are described in many references or manuals (e.g. Bruce et al. 2013, BS EN 2015, Kitazume and Terashi 2013). Conventionally, CDM columns are designed to have constant diameters over the improved depth as this facilitates the construction procedures. However, this design pattern is found inefficient in cases of spread footings or shallow foundations as the upper soil layers are naturally weaker than the deeper ones but are subjected to larger amount of induced stress from the superstructures.

Jan 1, 2019

By Alexander Filotti, Richard Kalson

"1. INTRODUCTION- WHAT IS P3 OR PPP ?The Public Private Partnership (PPP or 3P) is a project delivery scheme based on the government providing land and/or a concession agreement, and on a private entity providing the design, construction, financing, operation and maintenance of the project for an extensive duration of time (up to thirty years). At the end of the operation-maintenance period, the project is turned over to the public entity, which fully owns the project at all times. While there are many PPP delivery schemes used around the world, for the present paper, we are going to analyze the impact of the Design-Build-Finance-Operate-Maintain (DBFOM) scheme on the deep foundation specialty subcontractor. There are couple of reasons that the PPP delivery system started to be used and implemented not only by developed nations (e.g. United Kingdom, USA etc.), but also by the International Development Bank for delivering major infrastructure projects in developing nations. From the point of view of government agencies, some of the reasons to use PPP are the following:??The primary use of private capital in an era where borrowing and/or supplemental taxation represents too much of a political risk. Budget deficits and taxation limits are extremely hot topics in every election (national or local) and the level of education of the electorate in this area is making it more and more difficult for politicians to use borrowed funds and additional taxation finance sources for public projects. At the same time, we see an increase in the social expenditures of the government in parallel with a needed increase in expenditures on infrastructure due to aging and neglect.??Bundling the construction risks with the operational and maintenance risks naturally pushes the private entity to increase the level of innovation and communications in the primary phase ( the construction phase) in order to develop future process based upon the innovation and communications utilized in the operation and maintenance phase of the project. This is true if contractual incentives are properly structured because “all revolves around incentives. In a world of ‘incomplete’ contracts, where it is difficult to foresee and contract about uncertain future events, it is important to get the incentive structure right” (Grimsey and Lewis, 2004).??The transfer of very expensive risks such as differing site conditions, schedule, design, construction, maintenance and operation costs from the public authority to the private entity.??The timespan of development and construction of a PPP project is usually shorter than the traditional procurement process (e.g. “ the I-595 P3 provided capacity improvements fifteen years sooner than a conventional plan would have offered. In Maryland, an innovative expansion of the Seagirt Marine Terminal in the Port of Baltimore was completed two years ahead of schedule due to the P3 model. As a result, the Port of Baltimore is only the second port on the US East Coast to have unrestricted access to both a fully functioning 50-foot channel and 50-foot berth.”)"

Jan 1, 2017

By Heman Manchanda, Sandeep Sharma

Several infrastructure projects are in various stages of construction and planning in India and almost all of them involves open ground excavation extending to varying depths. These structures are generally multipurpose and fulfil several needs of the society, their failure can be catastrophic. The design and construction of deep open excavations is generally associated with a high level of risks due to a whole series of uncertainties involved, and the success of such projects depends on various factors including appropriate evaluation of ground behavior and response to excavation stages, correct choice and analysis of construction supports, control of ground water flow during excavation, etc. One of the most critical amongst all these is ground water flow during construction and stability of underground excavation depends to a large extent on ground water control. This paper uses numerical studies for the assessment of the potential impact of ground water and ground water movement for the design of underground deep structures. The studies are being conducted using PLAXIS 2D finite element software and analysis all construction stages to which an open underground excavation shall be subjected. The paper discussed in detail the impact of water table fluctuations and comparative evaluation of different water flow conditions – a) Different Stages of excavation in line with the construction sequence (Phreatic), b) Coupled flow analysis (Transient- 1 year and 2-year duration) and c) Steady state flow conditions. The paper also covers seepage calculation and design of dewatering system.

Sep 1, 2022

By Seth H. Hamblin, Leo J. Hart, John E. Regan

The Route 6 /10 10 Interchange Design/Build project, located in Providence, Rhode Island, involves the design and construction of five (5) new elevated bridge structures to replace and reconfigure the existing interchange and to provide a link between Route 10 northbound and Route 6 westbound. Due to site logistics, headroom restrictions, and depth to bedrock, 50 ton drilled micropiles installed in the deep medium dense sand strata were initially proposed as the deep foundation solution. Post project award, Geosciences Testing and Research, Inc. (GTR) performed various analyses and developed an alternate driven pile solution using steel Tapertube. The results of these analyses indicated that driven steel taper tube and steel pipe piles could develop greater capacities than the drilled micropiles in the granular soil layer, thereby reducing the number of foundation elements, decreasing construction schedule and providing a more cost effective foundation alternative. A comprehensive driven pile load test program was subsequently executed by GTR and the Design Build Team led by Barletta Heavy Division of Canton, Massachusetts, to assess the performance of Tapertube and steel pipe piles, including pile drivability, load-deformation characteristics under static and dynamic loading, and to develop site-specific design parameters in two (2) distinct test areas. The test pile program included dynamic, static compression, tension and lateral load tests on each test pile. Load test measurements were automated with embedded Vibrating Wire Strain Gages (VWSG) to measure load transfer with depth. The execution and results of the successful pile load test program are presented and offer unique case study and valuable data for the use of Tapertube piles on deep foundation projects in the New England region INTRODUCTION The Rhode Island Department of Transportation (RIDOT) Route 6 / Route 10 Interchange is located west of downtown Providence. Originally constructed in the 1950’s as a highway bypass around the historic Olneyville neighborhood, the interchange consists of a series of nine (9) bridges and ramps that serve as a vital east-west link between Interstate 295, 95 and 195. Based on recent bridge rating assessments, seven of the nine bridge structures are rated “structurally deficient”. With many bridge structures shored with temporary supports as many as 15 years ago, the interchange is in critical need of replacement. In 2018, RIDOT awarded the Route 6/10 Reconstruction Design-Build Project to 6/10 Constructors, Joint Venture. Led by Barletta Heavy Division of Canton, Massachusetts, the Design Build team includes O&G Industries, DW White Construction, Aetna Bridge Co. and AECOM. The scope of work includes the replacement of the bridges and ramps, and will provide direct access from Route 10 northbound to Route 6 westbound. Valued at over $400M (US), this is currently the largest project awarded in RIDOT history.

Jan 1, 2019

By Edward Jacobsen

The Oak Creek Power Plant in Oak Creek, Wisconsin is currently undertaking an expansion project. In order to supply cooling water to this facility, a 27' (8.2m) diameter tunnel will be bored, in rock; to connect to 4 vertical Intake shafts located approximately 1.5 miles (2.4km) offshore in Lake Michigan. In 2004, Case Foundation Company was awarded a lump sum contract to Install these intake shafts. When complete, the plant is expected to circulate upward of 2 billion gallons per day (7.5 billion liters) through this system. Two shafts were drilled in a (shortened) construction season in 2005 and the remaining 2 shafts and 4 liner assemblies were completed in 2006. Future connection to the tunnel, in 2007, will be accomplished by mining upward to reach the lower portion of each liner and then removing its internal bulkheads to permit the flow of the lake water into the tunnel.

May 11, 2007

By Christian B. Woods, Joe C. Drumheller

"Kenneth A. Huber, P.E., Langan Engineering & Environmental Services, New York, New York, USAThe dream to bring New Jersey Devils hockey to the largest city in New Jersey became a reality in the summer of 2005, when construction began for the Prudential Center in downtown Newark. The Prudential Center site encompasses an entire city block that had a varied history of uses ranging from a cemetery in the late 18th century, to a rail yard and train station for the now-defunct Central Jersey Rail Road in the 19th and early 20th centuries, to commercial development in the latter half of the 20th century. Each of these prior uses presented challenges to the design and construction of the Prudential Center that required innovative engineering solutions, including: archaeological investigation and exhumation of the former cemetery occupants, protection of historic buildings surrounding the site, and extensive demolition to remove old train bridge foundations.The design team was required to develop potential foundation systems for the arena. Several foundation concepts were evaluated for cost and constructability, including: driven piles, drilled shafts, and shallow foundations on improved subgrade. Following a detailed cost analysis and value engineering exercise, the decision was made to support the arena on spread footings following the completion of a multi-phased ground improvement program consisting of a combination of dynamic compaction and removal and replacement. To evaluate achievable allowable bearing pressure as part of the design, a dynamic compaction test section was performed within the building footprint prior to the start of production work; this resulted in an increase of the allowable design bearing pressure from 2 tons per square foot (tsf) to 3 tsf. This reduced the expected foundation costs by 30% and gained sufficient time in the schedule to allow for the completion of the arena in time for the New Jersey Devils 2007- 2008 hockey season.BACKGROUNDThe dream to bring New Jersey Devils hockey to the largest city in New Jersey became a reality in the summer of 2005, when construction began for the Prudential Center in downtown Newark. After several years of negotiating between the City of Newark, local landowners, area developers, and the Devils themselves, a deal was finally struck to erect Newark Arena, now known as the Prudential Center, right next to City Hall. This is not to say, however, that once the site location was finalized, that no further challenges were encountered in the construction of Newark’s new crown jewel."

Jan 1, 2015

By Paul Hewitt, Aaron Rastall

The New South Wales South Coast rail corridor is key infrastructure for both freight and passenger transport. Geomorphological and geological evidence suggests that land instability has been widespread throughout sections of the rail corridor, long before the first documented record of landslide activity in 1879. Major landslides occurred along a 25-km length of the South Coast Railway connecting Sydney and Wollongong because of significant rainfall events of the late 1980s. Since this time, several sites have been identified as subject to instability and treated progressively under a risk priority and safety management system. Two such sites comprise a station footbridge and overhead wiring structure (OHWS), both founded on high embankments overlying colluvial materials resulting in the structures’ potential movement and associated stability concerns. This paper presents these two sites as case studies, and discusses the project geology, geotechnical models developed, interpretation of monitoring data, and successful remediation of the rail structures using sleeved bored piles. The sleeved pile system was used to isolate bored piles, which separated the bridge foundations and OHWS from the moving soil mass to ensure the piles can carry the rail structure loads, unaffected by downslope soil movements.

Nov 1, 2022

By George Moses K, Mahendran K

Grouting is performed in rock masses in order to increase its strength properties and also to reduce the seepage. In the design of underground structures such as tunnels or caverns located in weak rock masses, grouting plays an essential role. Grouting is a complex process demanding high degree of skill and knowledge in understanding of grout flow and requirements for certain geological conditions. This paper discusses the design process for grouting in rock masses adopted for a cavern project and the practical difficulties faced during the execution at site. The design parameters of grouting includes the injection pressure, grout material properties and stopping criteria. The paper also discusses the various tests performed at site to evaluate the efficacy of the grouting process which was initially defined based on the design and previous experiences. The final grouting scheme suiting to the present geological condition is arrived based on the test results. The practical difficulties faced during the execution and the measures taken to overcome these are discussed in detail. This work shows the importance of state of art in the development of a grouting process based on geological and hydrogeological conditions prevailing at site and can be helpful in grouting design for weak rock masses.

Nov 1, 2022

By Srijit Bandyopadhyay, Aniruddha Sengupta, G. R. Reddy, Raj Banerjee

The objective of the present endeavor is to compare the performance of a pile raft system in foundation sand subjected to lateral loads. To study the behavior of pile raft system in sand a laboratory test was conducted on small scale model foundation system. The raft and pile was modeled by square concrete foundation of 250 mm x 250 mm x 15 mm in length, breadth and thickness and 25mm diameter and 250mm long circular pile located at the center of the raft. The system was tested under static lateral loads of 6.25N, 12.5N, 18.75N and 25 N respectively resting on dry Kasai River sand. A vertical surcharge pressure of 1.5kPa (10 kg) was applied on top of the model raft for each case. The results of the model tests have been simulated by a general purpose 3-D finite element software and the model has been validated with experimental results. The moments of the pile obtained from the model tests and those predicted by the numerical analyses for all the lateral loads matches reasonably well. For matching the trend of bending moments obtained from experiments, validation with theoretical results have been done with the help of Matlock and Reese (1960) approach for a single value of lateral loading. Moreover, a parametric study has been conducted with 5mX5mX0.3m raft size with 0.5m diameter and 5 meter long pile with increasing number of piles namely 2, 5 and 9 respectively to study the response in terms of moment and lateral deformation under available earthquake loadings, like Loma Prieta (1989) and Darfield Christchurch (2010). Bending moments of piles and load deformation curves for lateral loading have been studied for each case in which it is observed that the bending moments of pile significantly reduces (around 4 times) as the number of pile is increased to two, but it decreases to a nearly constant value (it saturates) as the number of pile is increased to five and nine. Moreover, the lateral deformation of piled raft system drastically reduces (around 2.4 times) for two pile system, and it saturates to a constant value with five and nine pile system. All these results indicate the constancy of stiffness irrespective of the number of piles in the piled raft.

Jan 1, 2015

By Tony D. Canale, Anthony Mazzo

"Times Square, arguably one of the best-known destinations in the world, has undergone and continues to undergo a re-development aimed at attracting corporate tenants to the area. Mueser Rutledge Consulting Engineers (MRCE) was involved with the planning, design and construction of the foundations for the Conde Nast and 5 Times Square sites, as well as Times Square Tower. These sites are pictured in Figure 1.This paper will focus on the design and construction of the deep foundations for Times Square Tower that was developed by Boston Properties. PROJECT DESCRIPTIONTimes Square Tower is 47 stories tall, with no setbacks and an overall height to top of crown of 730 feet (222.5m). It has two basement levels extending 30 feet (9m) below grade over the full site. As shown in Figure 1, the structure occupies the entire site and has a footprint of 22,000 square feet (2,044 m2), with a total rentable area of about 1.2 million square feet (111,480 m2). The planned use for the building is office space with retail at the ground level. When completed, Times Square Tower was the final building constructed as part of the Revitalization of Times Square. Due to the site constraints, designing and constructing the foundations was akin to placing the final piece of a puzzle.Times Square Tower provided numerous design and construction challenges that were a result of tight working conditions, heavy column loads, and a compressed schedule.GEOLOGIC SETTING AND SITE HISTORYThe Times Square area is part of the Manhattan Prong called the Manhattan Ridge, a formation of old and durable metamorphosed and folded bedrock, now termed the Hartland Formation. The bedrock generally has a thin soil cover and uneven surface overlain in some areas with a thin mantle of decomposed and/or weathered rock. Overburden soils include glacial and post-glacial deposits and recent fills.Transit improvements have been made in and around the Times Square area since the early 1900’s. The 1, 2 and 3 Subway Lines that run below 7th Avenue were constructed circa 1915 using cut and cover techniques and extend about 28 feet (8.5m) below grade. The N, R, Q & W Subway Lines that run below Broadway were also constructed in 1915 using cut and cover techniques and extend about 38 feet (11.6m) below grade. The 7 Line that runs below 41st Street was constructed later, using both cut-and-cover and tunneling methods as it runs below the other subway structures at a depth of about 55 feet (16.8m) below grade."

Jan 1, 2005

By Viswanadham B. V. S., Babu K. V

Wind energy is one of the most economical renewable energy sources. In order to support wind turbines onshore or offshore open-ended monopile foundations are widely used. Unlike conventional structures, wind turbine foundations experience a large magnitude of lateral loads in the order of 20 % to 30% of total vertical loads. The presence of soft clayey layers at shallow depth along the coastal region, offers lesser lateral load resistance to monopile foundations. One option to enhance lateral load capacity is by introducing fins to the outer surface of the monopiles. Studies pertaining to lateral load response of finned piles in clayey soils are very sparse. This paper presents some of the numerical model studies on the lateral load response of monopiles and finned piles in soft and stiff clay. In the present study, three-dimensional finite element analyses were performed on monopiles as well as finned piles. Analyses were performed in clay with different consistency varying from soft to stiff. Pile material is mild steel for all analyses. The pile section modeled as linear elastic material whereas soil was modeled as Mohr – Coulomb constitutive model with non-associated flow rule. Monopiles and finned piles having four and eight fins with different fin sizes and configurations are considered during the analyses. Finned piles advantage over monopiles to resist lateral load is highlighted in the present study. The results have shown that fins are effective to enhance the lateral load carrying capacity of monopiles and also it reduces the bending moment in monopiles for a given design load.

Sep 1, 2022

By John C. Niedzielski

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

"Full time inspection of drilled shafts by qualified personnel is a necessary part of construction. Detailed inspection procedures for routine inspection are provided in the Drilled Shaft Inspector’s Manual, published jointly by the DFI and ADSC: the International Association of Drilled Shaft Contractors.The use of NDT methods or other observation methods, such as probes, video camera inspection, remote shaft wall inspection devices or various calipers are not suitable substitutes for routine "topside" construction inspection as described in the Drilled Shaft Inspector’s Manual. However, these NDT and other "remote" or indirect observation methods are valuable alternatives to direct entry of personnel into drilled shaft excavations. They should be considered whenever appropriate to reduce the risks of direct entry of personnel into drilled shaft excavations.As described in the Drilled Shaft Inspector’s Manual, observations made during construction are essential for quality construction of drilled shafts. The shaft depth, diameter, plumbness, bottom conditions, reinforcement, concrete continuity, and bearing conditions are most easily checked during construction. Some of these observation methods include excavation around the shaft for relatively shallow inspection, down-hole inspection for end bearing conditions or rock sockets, and video camera devices for remote inspection. In rare circumstances, a drilled shaft can be extracted for inspection. Before concrete placement, the bottom of the shaft can also be probed by drilling or coring to determine if there are voids or soft zones in the material at the base of the shaft.The Drilled Shaft Inspector’s Manual focuses on traditional "topside" inspection for routine drilled shaft construction."

Jan 1, 2004

By Peter Cali

There is one organization in Sweden, The Swedish Deep Stabilization Research Centre, which has been working with these questions and there is also a project, Eurosoilstab, within European Union to take a manual for deep stabilization.

Feb 10, 2003

By William B. Conway

This paper will describe the large caisson pier foundations for four of the bridges crossing the Mississippi River in the New Orleans area; and will discuss some of the unusual problems encountered during their sinking. Certain settlement phenomena experienced during their service life will also be related: The four bridges in order of their construction: The Huey P. Long Bridge, River Mile 106.1, completed in 1935 The Greater New Orleans Bridge No.1, River Mile 96.0, completed in 1958 The Hale Boggs Bridge, River Mile 121.6, completed in 1983 The Greater New Orleans Bridge No.2, River Mile 96.1, completed in 1988 Each of these bridges employed large open-dredged concrete caissons as foundations for one or more of the river piers, with the smallest being the 65ft by 102ft caissons for Piers I and II of the Huey P. Long Bridge and the largest being the 99ft by 214ft caisson for Pier II of the Greater New Orleans Bridge No.2. The Huey P. Long caissons are founded in a dense fine sand at -170 while all of the other bridge caissons are founded in hard preconsolidated clay at elevations varying from -150 to -185. The Huey P. Long Bridge is currently being widened without increasing the caisson foundations under any of the river piers; and the design reasoning that led to this decision is presented.

May 11, 2007

By Aly Mohammad, Dongyi Yue

"The design of rock sockets for drilled shafts and piles proves to be a challenge for the Design Engineer. The magnitude of loads on the shaft and the behavior of the rock are critical in determining the required socket length. Several acceptable methods are available in the literature to analyze a rock socket under a combination of axial loads, lateral loads and moments. This paper will present a state-of-the-art methodology to analyze rock sockets utilizing deformation characteristics of the rock. This design methodology was implemented in the design of a major project in New York City.The project discussed herein is a marine transfer station planned for construction at East 91st Street along the East River in Manhattan. In order to support the piers and platform structures at a site with relatively shallow depth of the bedrock, rock sockets were required for the drilled shaft foundations. Rock sockets were utilized to provide the required fixity to the foundations and the structures. Acting at the top of the rock sockets are large shear forces and moments created by the lateral loads transferred from the structure.Upon review of the available techniques, a simplified method was proposed and used to analyze the rock sockets with a significant magnitude of lateral loading. The method recognizes two mechanisms through which the lateral shear and moment are transferred to the rock; a) load transfer through horizontal resistance of rock and b) the vertical shear resistance of the bond between socket and rock.The first load transfer mechanism was analyzed using the p-y curve method based on a rock model developed by Reese. The second was analyzed using a bond stiffness derived from the formula and curves utilized in the AASHTO Specifications for calculation of rock socket displacement. By comparing the two mechanisms, the main contribution to the large horizontal shear force that developed in the rock socket is identified.The paper will present a summary of the design methodology utilized in determining the length of the rock socket. It is believed that the presented method will provide substantial cost saving in selecting the most economical and efficient design length."

Jan 1, 2005

By G. W. Plant

This paper describes the design philosophy and construction details of piles between 25m and 32m deep to support 160m high and 110m base diameter cooling rowers for a major power station. It is sited on deep expansive soil where a vast plantation of Eucalypts had been felled. The depressed water table is expected to rise, leading to swell of the soil and uplift forces on the piles. These forces, combined with the complex loading from the cooling towers, led to design tensile loads up to 20MN (2 000 tons) per pile. When competent stable material was present hand excavated underreams 3m in diameter were constructed for the piles sup-porting the shells. However, in some areas it was not possible to form an effective underream and an innovative solution was sought. This comprised unstressed dowels in the underlying sandstone which were formed by percussion drilling through void formers cast into the piles.

Jan 1, 2010

By V K. Panwar, Sampat Raj

At a Fertilizer plant located in the southern part of India, 74 numbers of pump foundations have shown non-uniform settlements causing the tilting of pump foundations under self-weight primarily due to the presence of varying thickness of the heterogeneous subsoil beneath the pump foundations and soil erosion because of water seepage through deeper excavations in the close vicinity. Various corrective measures have been explored and taking due cognizance of the prevailing subsoil conditions, site constraints, and constructability aspects, micropiling has been adopted. This paper presents the site problem and details of remedial measures adopted for rehabilitation of the distressed pump foundations. The main objective of this paper is to provide guidelines for designer during design and detail engineering stage to avoid similar nature of problems and also to provide a solution concept to tackle similar nature of problem(s) if encountered at site.

Nov 1, 2022

By Michel Bustamante

The Arbre viaduct, 200 metres long, is the most important structure on the Belgian portion of the High Speed Train line between Paris and Brussels. The particular geotechnical conditions of the soil with carboniferous limestone affected by karstic phenomena, has prompted the designer to found the viaduct on systems of high capacity vertical and batter micropiles. The design of the working micropiles was validated by full scale tests performed on instrumented micropiles. The size of the structure and the deformation criteria to be met when HS trains are crossing the viaduct, together with the lack of references for such innovative structure, called for monitoring the movements of the piers as soon as the link was open to traffic. The authors report on the results of loading tests on micropiles and the results of settlement structure monitoring for a period of 4 years. Settlement of the foundation is estimated taking into account the group effect.

Jan 1, 2002

By Djk Arentsen

A new technique to drive tubular piles by impact hammer inside the pile has confirmed a dramatic reduction of noise and the opportunity to save steel. Also a reduction in driving time and a higher bearing capacity has been observed during a test program of this technique. As part of the so-called "Down-the-hole" driving technique, a wave equation analysis has been developed to calculate driveability and pile stress. The main feature of the new "Down-the-hole" technique is the development of a patented device allowing uncoupled penetration of pile tip and pile shaft, which makes it possible to drive both closed or open end piles and reduce the stress level induced in the pile wall. During a test program, a number of instrumented piles were driven and compared with traditional driving of the same pile with the same hammer on top (also instrumented). Also the stresses and performances were compared with precalculations. This paper, explains the technique and presents the test and noise results, in comparison with traditional top-pile-driving. The "Down-the-hole" driving technique is an interesting alternative for special applications where traditional pile driving requires a large wall thickness or in areas where noise is a hot item.

Jan 1, 1996