Search Documents

By James J. Cahill

Contractor's working in an urban environment face a multitude of working conditions. There is no typical "Downtown" job site. From afar we just see the skyline, or up close a specific building. This, of course, does not give us a clue as to the site conditions the foundation contractor faced in doing his work. The open, downtown building site is still available on some projects, but they are becoming rare as our cities are becoming more developed. A typical site today might include any one or several of the following problems: A. Deep pit with no ramp access B. Multi-type known or unknown obstructions C. Height limitations D. Load restrictions E. Existing adjacent building founded on shallow foundation F. Existing foundations G. Existing tunnels, utilities or subways

Jan 1, 1991

By George Piscsalko

There are numerous methods currently available to assess the integrity of drilled shaft and ACIP piles. Each method has its advantages and limitations. This paper will compare the various available methods as well as introduce a new method for assessing integrity of drilled shafts and ACIP piles. This new method, known as Thermal Integrity Profiling, determines the integrity of the shaft both inside and outside the reinforcing cage by measuring the hydration temperature of the concrete along the length of the shaft. These temperature measurements can be made by either passing a thermal probe through a standard Cross Hole access tube, or from embedding thermal wires within the shaft. This Thermal Integrity Profile method will be described in detail and one case history will be presented. Additional testing methods which will be compared include low strain Pile Integrity Testing and Cross Hole Sonic Logging. Advantages and limitations for each method will be discussed.

Jan 1, 2011

Jan 1, 2000

By Patrick E. Durnal

The Richmond-San Rafael Bridge was built in the early 50s' and was first opened to traffic on August 31, 1956. Among California's longest steel bridges, it spans more than 21,000 feet across the northern portion of San Francisco Bay. It is one of six toll bridges currently undergoing seismic retrofit in the Bay area. Current retrofit criteria require the structure not to collapse in a Magnitude 8.3 earthquake lasting 45 seconds on the San Andreas Fault. The earthquake epicenter is 10 miles to the west of the Bridge, near the mouth of San Francisco Bay. Another major fault is the Hayward Fault, with a potential of a 7.5 magnitude earthquake. It is only 4 miles east of the eastern end of the bridge. The retrofit criterion is that the structure survives these earthquakes without collapse or loss of life, and that they are capable of repair within a period of one year. Therefore an energy absorbing, ductility and nominal resistance based approach to the retrofit design have been adopted for the retrofit of this bridge. Foundation Retrofit The foundation retrofits were designed to satisfy of drift criteria of 6 inches at the base of the footings, and to keep the existing H-piles from experiencing unacceptable levels of permanent soil displacement and /or structural rupture. Full-scale structural lateral load testing of BP14x89 piling, to rupture, has helped to determine the drift criteria. However recent non-linear analytical results, have led to a redesign, which may allow for 12 inches of drift. The as-built analysis of the Micropile piers determined that those piers would not exceed the 6-inch drift criteria so lateral resisting shear piles were not needed at those piers.

Jan 1, 1998

By Wolfgang G. Brunner

The closing of the gap in the European waterway- net is one of the big and challenging traffic projects following the German reunification. The water canals in the North German plain connect the Rhine river, the border between Germany and France, with the Oder, the German border river to Poland. As early as in the 30's of the 19th century the planning and construction of a ship- lift and a canal bridge started, in order to close this last big gap in the system between the Mittelland Canal and the Elbe- Havel Canal near Magdeburg. This main waterway connects the West of Germany, known for its coal mines and steel mills, with the capital Berlin, and from there it goes on into Poland. The building activities started in 1934 but came to a complete stop in 1942 because of the war. The communist government in East Germany was not interested in continuing this huge project, including the ship lock Rothensee, the canal bridge crossing the river Elbe, the former border river between West and East Germany, and the lock Hohenwarthe due to lack of political backing along with low construction capacity.

Jan 1, 2000

By C. Vipulanandan

It is critical to monitor the ground conditions during excavation and drilling of boreholes during construction to identify possible changes in the soil and rock formations. Drilled shafts are increasingly used as foundations to support structures, bridges and other facilities in geomaterials such as soft-rocks and hard clays. Locating the bottom of the borehole during construction with the required design strength is critical. Hence developing a simple device that could be easily adapted/used with the drilling tool was of interest in this study. Determining the shear strength of the geomaterial in the borehole and at various elevations including the bottom of the borehole can lead to better quality control of construction by identifying the various layers based on strength. In this study, a down-hole penetrometer (DHP-CIGMAT) was designed, built, calibrated and tested in the field to determine its effectiveness in measuring the strength of soil/soft rock in the boreholes. Based on limited field tests, linear correlations between geomaterial strengths and DHP-CIGMAT deflection have been developed. The DHP-CIGMAT can be used to identify soils and soft rocks.

By Walter E. Vanderpool

Full scale load tests are frequently performed immediately prior to deep foundation construction to verify the design assumptions. Occasionally, load tests are performed during design development and applied to the final design for critical and non-redundant structures. We believe that full scale load tests can be very valuable and economical for projects, especially in a geologic environment where the record of full scale load testing is very limited or non-existent. The load testing for the Utah Transit Authority?s Airport Light Rail Trax project provides an example of the advantages of a load test in design development. The savings realized by the owner was in excess of $800 thousand dollars.

Jan 1, 2011

By Satyajit Vaidya, Rudolph Frizzi, Luis Berroteran

This paper presents design and construction challenges associated with a high-capacity rock-socketed drilled pile foundation system for a 60-story building recently constructed in an urban environment. The site is in very close proximity to surrounding 1-to-6-story buildings and a commuter rail subway tunnel structure. High compression, uplift, and lateral loads imposed by the tall, slender tower constructed over a relatively small site footprint posed a significant design challenge due to the close proximity of the subway tunnel and other structures. Construction challenges included those associated with advancing the drilled pile casings through overburden materials using internal flush method mandated by the Transit Agency, advancing the casings through very dense glacial till materials encountered above top of rock, and drilling rock sockets in variable rock conditions. This paper provides a brief overview of the site and subsurface conditions, and discusses the resulting design and construction challenges for the drilled pile foundation system and how they were addressed. SITE AND SUBSURFACE CONDITIONS The 8,350-square-foot site is located in a busy neighborhood in downtown New York City (NYC). Buildings neighboring the site are supported on shallow foundations, and their basements extend about 15 feet below the sidewalk level. A NYC-Landmarked building is located within a NYC Department of Buildings (DOB)-designated 90-foot influence limit from the Project site. NYC Transit Authority (NYCTA) subway tunnel and station structures are located in close proximity to the Project site. The subway tunnel structure extends about 50 to 55 feet below the sidewalk level. Although the upper portion of the tunnel structure is about 13.5 feet away from the site property line, the lower portion is only about 1 foot away from the property line. A site location plan is presented as Fig. 1. Geotechnical borings revealed subsurface conditions generally consisting of successive strata of surficial fill, sandy and silty soils, and glacial till (predominantly consisting of cobbles and boulders) overlying mica schist bedrock. A generalized subsurface profile is presented in Fig. 2. The surficial fill stratum was about 10 to 23 feet thick, and generally consisted of loose to medium dense sandy soils with varying proportions of silt, gravel, and miscellaneous debris such as brick. The underlying sandy and silty soil stratum was about 60 to 79 feet thick and generally consisted of loose to medium dense inter-bedded layers of fine to coarse sand, silty fine sand, and silt. The underlying glacial till stratum was about 26 to 70 feet thick and generally consisted of cobbles and boulders embedded in a very dense soil matrix. Top of bedrock was encountered in the borings about 110 to 150 feet below sidewalk level. Groundwater level was measured at about 30 feet below sidewalk level.

Jan 1, 2018

By Alexander B. Reeb, Richard J. Varuso, George M. Filz, Jehu B. Johnson

"T-walls, which are concrete floodwalls in an inverted “T” shape, are an integral component of the Greater New Orleans Hurricane and Storm Damage Risk Reduction System (HSDRRS). In order to resist large lateral flood loads, T-walls are typically supported on long batter piles that extend through the weak and compressible clays and peats commonly encountered in southern Louisiana. Since the piles are battered, settlement of the compressible foundation soils can result in loads acting normal to the piles and induce pile bending moments. Therefore, the design of pile-supported T-walls is a complex soil-structure interaction problem that requires detailed and careful numerical analysis to accurately estimate the stresses and bending moments in the piles. For this paper, numerical analyses were performed for three cross sections that each included a two-pile T wall system that was installed within a 15-ft tall new levee embankment. The cross sections were identical except that the elevation of the T-wall base was varied. This paper discusses the analyses, and it compares the influence of settlements and flood loading on the pile stresses and bending moments. In addition, this paper includes general recommendations for the analysis and design of pile-supported T-walls in practice.INTRODUCTION AND BACKGROUNDThe recently completed Greater New Orleans Hurricane and Storm Damage Risk Reduction System (HSDRRS) includes 350 miles of levees and floodwalls and is designed to defend against a 100-year storm surge event. The floodwalls predominantly consist of I-walls and T-walls. I-walls are comprised of a sheet pile wall curtain capped with a monolithic concrete wall above grade. T-walls are similar to I-walls, but they include a wide concrete base at grade, which forms an inverted “T” shape, and they are generally supported by long batter piles that provide additional lateral and rotational stability for resisting flood loads.During Hurricane Katrina, several I-walls failed, resulting in large breaches and devastating flooding (Duncan et al. 2008, IPET 2009). T-walls on the other hand performed quite well, including T-walls that were overtopped and eroded on the protected side, yet still did not collapse. As part of the HSDRSS, more conservative designs and height restrictions were required for I-walls (USACE 2011), and a number of I-wall sections were replaced with T-walls. However, the design of pile-supported T-walls is complex and requires careful consideration of both flood loading and settlements."

Jan 1, 2017

By S. T. Kok

This paper presents a case study in West Malaysia for passive piles failure in very soft marine clay in open excavation. In this particular case, the thickness of the very soft marine clay ranges from 5 m to 7 m (16 ft to 23 ft) from the ground surface. Preliminary site investigation reported SPT ?N? value of zero for the very soft marine clay. The design was based on a deep foundation utilizing driven piles to support the superstructure. During pile cap construction, the piles were subjected to uncontrolled open excavation, inducing bending moment in the piles, resulting in some cracked and broken piles. Analyses were carried out using an existing three-dimensional finite element code with a non-linear soil model to predict the response of these piles during excavation. Finally, the predictions of pile responses during excavation were compared satisfactorily with the observed results.

Jan 1, 2009

By Bengt H. Fellenius

THIS PAPER deals with the analysis of results from axial testing of vertical single piles, i.e. the most common field test per-formed. Despite the numerous tests which have been carried out and the many Papers which have reported on such tests and the analysis thereof, the understanding of pile test loading in current engineering practice leaves much to be de-sired. The reason for this is that the engineers have concerned themselves with mainly only one question: "Does the pile have a certain least capacity?", finding little of practical value in analysing the actual capacity and the pile-soil interaction. This Paper aims to show that engineering value can be gained from elaborating on a pile test ? during the actual testing in the Held, as well as in the analysis of the results. The first portion of the notes make use of an earlier Paper by the author (Fellenius. 1975). However, additional views and recent literature have been incorporated.

Jan 1, 1988

By Z. G. Lin

In Xian, China, compaction by means of soil (or lime-soil) piles is one of the effective methods widely used for densifying loess and eliminating its collapsibility. However, as a result of groundwater table rising, it is no longer applicable in many areas. This paper is the summary of the first-time use in Xian of sand-gravel compaction piles aimed at densifying the miscellaneous fill (already partially under water) and saturated loess at a certain project site. In-situ tests, conducted before and after the treatment and including several kinds of penetration tests backed up and confirmed by a set of plate loading tests, yielded very satisfactory results, strongly testifying to the viability of the method.

Jan 1, 2010

By G. G. Goble

Significant progress has been made in the past decade in determining the load bearing capacity of pile foundations. Developments in the means of prediction of pile capacity as limited by soil strength have been substantial, particularly in the use of dynamic methods. The use of currently available equipment, analytical procedures, and practices in the field, will often produce material economies on a job by allowing increased loads with proven factors of safety. This approach justifies the minimum number of piles required for a safe foundation in a wide range of job sizes and soil conditions. To avoid exposing the reader to excessive detail in the body of this paper, technical topics have been covered more thoroughly in several appendices. I. Wave Equation Analysis of Piles Appendix A II. Dynamic Monitoring and the Pile Driving Analyzer Appendix B III. Case Method Capacity Calculation Appendix C IV. Case Pile Wave Analysis Program Appendix D 1 Preliminary Analysis In designing driven pile foundations, there must be a close relationship between design, construction control procedures, driving practices, and the size of the job. Small commercial buildings or residences involving loads that are only a fraction of the pile capacities do not justify the expense of detailed design processes or elaborate construction controls. Nevertheless, some preliminary analysis of the job requirements and a limited subsurface investigation must be made to understand existing conditions and the possible foundation solutions. In other words, it is necessary to determine that driven piling is the best overall choice of foundation.

Jan 1, 1988

By N. S. Yet

This paper shall present the design and construction of bored pile and diaphragm wall for the proposed MHA complex in Singapore. The work was carried out by L&M Foundation Specialist Pte Ltd and PWD Consultants Pte Ltd was the consultant for this project. A brief description of the project is first presented to illustrate the scope and scale of the work involved, which includes the construction of bored piles and diaphragm walls and installation of steel stanchions in the bored piles. This is followed by a description of the methodology used to analyse and design the wall and bored piles. As both towers in this project are supported on bored piled foundation and are constructed by top down construction method, the analysis of the wall has taken into consideration the sequence of work phase by phase and this was carried out by means of a commercial finite element program called CRISP. Modelling of the problem will be briefly described and the findings from the numerical analysis will be presented. This is followed by a description of the structural and geotechnical design aspects of bored piles. The paper shall then describe the difficulties encountered for this project and solution used to solve the problem. The subsoil condition will be described with special mention on the encounter of very strong granitic rock at depth above the maximum excavation level of the basement at certain locations, hence necessitating the drilling of rock for a considerable depth for both bored piles and diaphragm wall. At this juncture, the construction method used to drill through the rock will be briefly described. For construction of bored piles, penetration of rock was carried out by chiselling or drilling using reverse circulation rigs. For construction of diaphragm wall, it requires the employment of Bauer hard rock cutter which uses cutting wheels fitted with roller bits and are capable of excavating into granitic rock of compressive strengths more than 100 MPa.

Jan 1, 2000

By Howard Roscoe

Linking Ashford International Station to the new Channel Tunnel Rail Link required over 5000 rotary bored and CFA (continuous flight auger) piles to form tunnel walls and viaduct foundations and to support overbridges and trackside barriers.. Much of the work was carried out close to the existing railway infrastructure. Plunged columns were used to maintain traffic flows over the tunnel site during construction. The results of an extensive programme of vertical and lateral load tests on bored and CFA piles in heavily overconsolidated Weald Clay are compared to illustrate the relative importance of stress relief and of prolonged exposure to bentonite. The completion on schedule of this major piling and ground engineering contract (value £30 million) demonstrates that collaborative working in partnership produced cost effective solutions to a series of challenging technical and logistical problems.

Jan 1, 2002

By Clyde Baker

Drilled shafts for many situations offer an economical alternative to driven piles. The Federal Highway Administration (FHWA) has spent considerable time and money in research and developing design and construction guidelines for drilled shafts. However, the full potential of the technology may not be realized because of the uncertainty of the effects of construction on the actual service behavior and the lack of either reliable quality control tests to check for or evaluate defects, or inexpensive load test procedures. Static load testing is very expensive and it is not feasible to load test each shaft on a project. Therefore, other means are necessary to confirm or evaluate the integrity of the completed drilled shaft or to determine the capacity of the completed shaft.

Jan 1, 1989

By Martin B. Hudson, Daniel Brescia, Zhangwei Ning

Due to the complexity and sensitivity of surrounding environments, instrumentation and monitoring (I&M) is critical for many urban deep excavations. The objects to be monitored include shoring bulkheads, retained embankments, adjacent buildings and roads as well as underground utilities. However, there are also plenty of constraints on the implementation of I&M such as: congested site space, difficult access to instruments, coordination among multiple contractors, and installation permits for private or public properties. Because of these constraints, sometimes the implementation of the initially planned I&M is delayed, its scope is reduced, and/or the continuity of monitoring is interrupted. For these reasons, it is important to implement the I&M with robust and redundant capabilities while providing minimal interference to the project construction and schedule. This paper describes state-of-the-art I&M technologies including automatic motorized total station (AMTS) with camera and automatic leveling device, reflectorless AMTS and IoT- based wireless sensors based on a case study of an on-going deep excavation project. INTRODUCTION In urban environments, deep excavations requiring the construction of temporary shoring bulkheads are becoming increasingly common, with the associated need to provide protection of the surrounding built environment during construction. Protection of the surrounding environment requires planning, engineering, construction, monitoring, and excessive shoring movement mitigation. The I&M is a vital component of the deep shoring implementation. In public projects, geotechnical I&M is often placed within the general contractor’s scope, whereas the majority of deep excavations are privately undertaken. For those private developments, sometimes the developer contracts the geotechnical I&M directly with the project geotechnical engineer or by a geotechnical I&M specialist hired by the project geotechnical engineer. In either the public project or private development case, the effective deployment of the I&M system relies heavily on coordination and collaboration with the project contractor.

Jan 1, 2018

By Bernard Hertlein

¦ Drilled shafts resist scour seismic loads better than groups of driven piles ¦ Drilled shaft construction creates less noise and vibration than driving piles ¦ Drilled shafts permit direct observation of bearing stratum, and confirmation of location ¦ Drilled shafts are cost effective

Jan 1, 2001

By Ganesh Kumar S.

"Soil reinforcement using stone columns is one of the well-developed ground improvement techniques for soft clay deposits. The load carrying capacity can be further improved by encasing it with geosynthetic material around the column which offers effective lateral confinement, prevents column contamination with improved drainage and strength characteristics. Improvement of undrained shear strength using vacuum consolidation is a type of hydraulic modification technique in which negative pore pressure will be developed which increases the effective stresses in soil without changing the total stress. The improvement in effective stress resulted in improved undrained shear strength of surrounding soil. In this research work, combined geosynthetic encased stone column and vacuum treatment method is examined for improving of extremely soft clay soils. The improvement in the time rate of consolidation and load carrying capacity of stone columns after vacuum treatment was studied using experimental investigations. It was observed that both load carrying capacity and stiffness of the encased stone column increased significantly with vacuum application. Also, application of vacuum accelerates rate of primary consolidation settlements. With this reduction in time, the construction activity can be accelerated which makes the project economically beneficial.INTRODUCTIONThe rising demand for the land for country’s infra-structure compels the engineers to work with even soft clay deposits which are not suitable for construction activities. As these soils have low bearing capacity and excessive settlement characteristics, ground improvement methods will be required before commencing construction. Among all available treatment methods, soil reinforcement and hydraulic modification technique are well-known popular techniques for its reduction in time required for consolidation settlement with improvement in load carrying capacity. When stone columns are used as a reinforcing member, it creates drainage with improves bearing capacity (Greenwood, 1970; Mitchell & Huber, 1983). However, the limitation includes lack of lateral confinement in very soft clay deposits, possibility of contamination, reduction in drainage path all which leads to the failure of stone columns (Mckenna et al, 1975). To overcome these limitations, encasement using geosynthetic material was adopted around the column which offers better lateral confinement, prevents intrusion of finer clay particle inside the column and provides effective drainage path with improved load bearing capacity characteristics (Van Impe, 1986; Raithel et al. 2005; Short et al. 2005; Borkemper et al. 2006; Murugesan & Rajagopal 2010; Kumar et al. 2014)"

Jan 1, 2017

By Y. K. Wong

This paper describes in detail various problems concerning the construction of a pile-raft foundation supporting a 42-storey tower block. The subsurface generally consists of highly weathered sedimentary rock. A comprehensive instrumentation program is implemented to monitor the behaviour of the foundation system throughout the construction period of the superstructure. Instrumentation observations are highlighted in the second half of the paper.

Jan 1, 2010