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By R. K. M. Bhandari

Geotechnical investigation for a LPG plant located in Assam state - an area of high seisimicty - revealed a layer of loose to medium silty sand susceptible to liquefaction at some depth below the finished ground surface. Liquefaction analyses were carried out using simplified Seed's approach as well as considering the progressive buildup of pore pressures with cyclic earthquake loading. Seismic settlements were computed for areas where the analysis indicated partial liquefaction. Pile foundations in areas where complete liquefaction was indicated, were treated with gravel drains to prevent buildup of pore pressures. The paper presents and discusses the liquefaction analyses, effect of non-liquefiable overburden soil on the liquefaction potential of the silty sand and the remedial measures that have been taken to ensure safety of the pile foundations in transmitting vertical and lateral loads.

Jan 1, 1996

By Kam Ng

For bridges or buildings that may be subjected to large vertical and lateral loads, drilled shafts offer an economic foundation solution. While the current drilled shaft design practice is considered adequate, introducing a performance-based approach to designing the drilled shafts will make their design more cost-effective and produce more dependable response. This concept was examined using analysis of 41 drilled shaft load test data from several states. This process identified the challenge with the lack of information from the Osterberg (O-cell) load test method to characterize the full top load-displacement response. When a typical single O-cell is utilized in a drilled shaft test, depending on the location of the O-cell and the geomaterials present along and beneath the shaft, the load test result typically quantifies either the side resistance or end bearing reaching the ultimate load-displacement curve but not both components. This limitation hinders the determination of a suitable shaft resistance as a function of a target top displacement. To overcome this challenge, an improved procedure is proposed for establishing the full load-displacement curve based on data gathered from one O-cell. The method will be presented in the paper for three different cases (i.e., side resistance reaches the ultimate during the test, end bearing reaches the ultimate during the test, and neither components reach the ultimate values). Because it allows the characterization of the full load-displacement curve, the proposed procedure will allow performance-based design of drilled shafts with due consideration to settlement while satisfying the Load and Resistance Factor Design.

Jan 1, 2013

By John A. Egan, Nathaniel Wagner, Micaela Largent, Jonathan P. Stewart, Debra Murphy, Jeremy Butkovich

The Millennium Tower is a 58-story reinforced concrete building that was constructed in San Francisco, California between 2005 and 2009. The Tower is founded on an embedded pile supported mat with pile tips bearing in dense marine deposits that overlie an over-consolidated marine clay layer known locally as Old Bay Clay. This clay layer experienced stress increases from Tower self-weight and from multiple episodes of de-watering between 2006 and 2018 at the Tower site and neighboring sites. Settlements of the Tower foundation have been measured since 2006 and lateral deflections of the Tower have been inferred and measured since 2009. Available information on this case history include geotechnical site conditions and data from a monitoring program that tracked foundation settlements, Tower tilt, groundwater levels at the Tower site, and ground inclinations over time. This presentation will discuss the ground deformation mechanisms that caused the observed movements, the degree to which the movements can be predicted, and lessons from this case history for the design of deep foundations for tall buildings in San Francisco and geologically similar regions.

Sep 8, 2021

By Robert Small, Amshu Chappa, Ihab Allam

The Biosolids Digester Facilities Project (BDFP) is located in southeast San Francisco. The jobsite is bounded by active Caltrain and Union Pacific Railroad tracks on the west side and the existing Southeast Treatment Plant (SEP) on the north, south and east sides. The existing SEP was constructed in the 1950s and portions of the facility have reached their operational life. The $2 billion BDFP will replace and relocate the outdated existing solids treatment facilities with more reliable, efficient and modern technologies and facilities. In addition, the nearby Bayview and Hunters Point neighborhoods will benefit from the improved odor control. MWH/Webcor, a joint venture, as the construction manager general con- tractor (CMGC) for the project. As part of an alternate delivery method set forth in the prime contract, the CMGC was permitted to propose the use of a core trade subcontractor partner for the SFPUC's approval to provide precon- struction services. The CMGC identified three major scopes (electrical, mechanical and foundation) where a core trade partner would be able to assist

Jan 1, 2023

By Andrew Pontecorvo, Steven Lowe, David Sposito

Buildings with large height-to-width ratios require foundations with significant uplift resistance. This paper presents a case study of the permanent rock tiedowns installed for One Manhattan West, a sixty-seven-story office building in midtown Manhattan. Site access and schedule dictated the size of the equipment for installing the tiedowns would be limited to drilling a 16 inch (406 mm) diameter hole. A three bar configuration of 3 inch (76 mm) diameter high strength threaded bars was chosen to develop an allowable capacity of 923 tons (4060 kN) per tiedown. Although the quality of the rock at the site was generally high, a challenging geologic condition emerged during the installation of one of the tiedowns requiring a creative installation procedure. Although the three bar configuration performed relatively well there are challenges with loading and testing this bar arrangement. Unlike single bar tiedowns that are typically tested with a high success rate, testing of a multiple bar system can result in some unsatisfactory results. This may be attributed to the installation challenges, difficulty loading each bar uniformly and/or the method of monitoring the test. Understanding the complexities is necessary to improve the testing results and achieve similar reliabilities of single bar systems.

By Sherrill Gardner

Vibratory drivers have been used since the 1930s to drive and extract piles. Vibratory pile drivers have the capability of significantly decreasing pile installation time, especially in granular type soils. However, they have not been widely accepted because of the uncertainty in estimating the bearing capacity of the driven pile. When driving bearing piles, the industry standard method for obtaining load carrying capacity of a pile installed with a vibratory driver is to redrive with an impact hammer. The advantage of improved productivity is lost with the redrive procedure. Currently, there is no other method to predict the capacity of these bearing piles installed with a vibratory driver. The Naval Civil Engineering Laboratory (NCEL) is making progress towards being able to estimate the bearing capacity of these piles. This paper describes field testing and corresponding analytical modeling of the vibratory driver-pile-soil system. The following sections describe the development of the numerical model and techniques for collecting field data. A discussion of the prediction of the pile driving process based on field test data is followed by suggestions as to the additional work that should be done to further verify the model to a point where it can be used with confidence.

Jan 1, 1987

By L. J. Whitworth

Five trial piles were constructed during the trial pile programme for the Birmingham International Convention Centre. In addition, trial piles have been tested on two other sites in central Birmingham. Methods of pile construction were conventional sandstone rock sockets, sleeved piles and voided piles. The results of these load tests are compared with the theoretical predicted behaviour based on the results of unconfined compressive tests of rock core taken on the Convention Centre site and on other sites in the central Birmingham area. On the basis of this work, the various design procedures are discussed.

Jan 1, 1989

By Jack Hayes

Vibrating wire strain gages have proven to be a very reliable and effective tool for the measurement of strains associated with the loading of bored piles (drilled shafts). However, when these strains are used to calculate the load, or stresses in the pile, the results can sometimes be confusing and/or difficult to interpret. This paper describes some of these situations, using examples from actual case histories, and discusses some of the difficulties associated with residual load effects, curing and temperature induced strains, load stress distribution effects, estimated modulus and area.

Jan 1, 2002

By D. Y. Peng

A Large Sub-structure with open top of S.Y.P. float line requires a 90m x 50m in plan and 13m-deep excavation in soft soil, Shanghai. The geological conditions in site are rather severe. The technology specifies that no permanent braces nor partition walls are allowed to be constructed inside. After a series of discussions the scheme of semi-gravity type cellular D-walling without any braces or earth anchors is finally adopted and successfully executed by SFEC. This paper deals with the technical problems in the design, construction and in-situ monitoring we met with in this difficult project.

Jan 1, 2010

By Rob van Dorp

Most traditional foundation designs are based on soil investigations using Standard Penetration Testing (SPT), sometimes combined with static load testing on sacrificial trial piles. However, this design approach has two major shortcomings. First, SPT data do not provide direct and continuous informa- tion about soil resistance as a function of depth. Second and more important, because of the relatively wide spacing between borehole locations, SPT soil investigations do not provide adequate information about variability of soil profile and/or soil resistance over the project area. Preliminary pile load testing on an SPT location can compen- sate for the first disadvantage but cannot address the second disadvantage. A design approach based on an adequate soil investigation campaign with Cone

May 1, 2022

By V. T. Ganpule

The effect of Sulphate and Chloride is well understood by the engineers. Most of the codes stipulate permissible limits for sulphate and chloride content in groundwater. Relatively few reference are available about the effect of organic acids on pile concrete. While executing a pile foundation work around Bombay, the authors came across the peculiar phenomenon. The routine testing of water has indicated that water is non-aggressive; however, on exposing the piles, the piles were found to be highly detonated. The testing of water on the guidelines followed by engineers associated with flow through pipes revealed that water is corrosive as per the Ryznar index concept. The present papers discussess the significance of Ryznar index in under water concreting.

Jan 1, 1996

By Shamsher Prakash

Estimation of vertical load carrying capacity of a single vertical pile under earthquake loading is an important task of a design engineer. Lateral vibration of vertical pile is highly influenced by the magnitude of vertical load. Several load reversal, during earthquake loading introduce gap between pile soil interface which reduces its load carrying capacity and increases lateral motion. This paper presents a simple time domain numerical scheme to estimate the lateral pile response, considering the loss of contact of pile at pile soil interface, during impact and earthquake loading. The motion of the pile is limited in the vertical plane. Time domain has been discretised into small intervals. The non linearity of soil properties has been taken into account by discretised Winklers model with Wolfes frequency independent mass spring dash pot coefficient for geometric damping. Suitable software has been developed which keeps track of the load reversal point of each elements.

Jan 1, 1996

By L. Z. Xie

The results of the experimental study on the static behavior of single piles subjected to repeated and reciprocating axial loadings are recommended in this paper. Tests of four full-scale single piles of two different lengths under repeated loading and those under reciprocating loading have been conducted using the slow maintained load test method. All the eight piles were instrumented with strain gages located along the shafts. The study showed that for repeated loads below a certain critical value the total displacement of the pile top approached gradually a constant value. However, any repeated load greater than the critical value resulted a residual displacement per cycle, and that the reciprocating load capacity of a pile was dependent on the ultimate bearing capacity of the pile in tension and both were in the direct ratio.

Jan 1, 2010

By Ashley Shirer

Have you heard a geotechnical engineer rail against using the word "dirt"? The typical maxim is: "It's not dirt, it's soil!" This axiom is so prevalent that it is joked about on the construction site. How did we get to the point in our profession that soil is too technical to understand, while dirt is not viewed as important? Take a moment and think about the images that come to mind by the word soil. Responses range from the sand at a playground to the mud that sticks to the bottom of your shoe, the dark loam found in gardens to the firm earth under your feet. But do you know where the term soil originated? Or how it was intended to be used? This article looks at how word choice can lead to very different motivations for owners, designers and constructors.

May 1, 2023

By Matt Sotirin

The Santa Fe train station and passenger rail platform were constructed in the downtown district of Fort Madison, Iowa, over a century ago. This landmark building and rail platform were in need of major renovations and rehabilitation in order to restore the site to a functioning railway train station. A multitude of key players from various public and private parties were involved in the design and construction of this project site. Part of the project consisted of constructing the passenger platform. The original design included helical piles to provide foundational support for the platform. Challenges occurred during construction due to the presence of an obstruction in the form of a poured concrete slab in the immediate area where the helical piles were to be installed. The contractor worked with the engineer of record and other consulting parties to value engineer the helical pile design and utilize self- drilling micropiles as a replacement to the specified helical pile system.

Oct 1, 2022

By Anne Lemnitzer

Full-Scale cyclic field testing was performed on a 3x3 pile group consisting of nine cast-in-drilled-hole (CIDH) reinforced concrete shafts and a comparable single-shaft in order to investigate group interaction effects, derive p-y curves for reinforced concrete fixed head piles and to validate currently available p-multiplier models. The piles are identical in diameter of d=2 ft and were tested in similar soil conditions. The single pile as well as in three piles within the pile group were instrumented with internal sensor instrumentation to record pile curvatures. External instrumentation was used to control and measure the lateral displacement of the specimens. Experimental studies were supported with analytical models to enable comparisons and offer design recommendations. All test specimens were tested to structural failure and group interaction factors ranged between 0.8 at small displacement levels and increased towards unit near structural failure. A set of p-multipliers was found to reproduce an accurate fit to the available test data.

Jan 1, 2010

By J. S. Ward

In a well-written set of contract documents, the probability of conflicts arising during the course of construction is minimized. However, no matter how complete may be the technical language in the contract plans and specifications, the possibility always exists that conditions may be found in the field that were not anticipated at the time the design was formulated. In foundation engineering work, this is commonly referred to as "differing site conditions." When such a conflict arises in the field, the most expedient manner of resolution would be for the parties to the contract to meet and to amicably resolve the issues rather than use the long and costly adversarial approach of the litigation system currently prevalent in the United States. This rapid solution to the construction conflict can be accomplished through an alternate dispute resolution technique that includes mandatory discussion, mediation and arbitration to be initiated immediately following the inception of the dispute and to be concluded in not more than 100 calendar days from the time the dispute originated.

Jan 1, 2010

By J. L. Liu

Long-term maintained load test on the bored pile group in unsaturated silty soil has been carried out. And the research on the time effects of bearing behavior of pile group has been done by the method of installing pressure cells and reinforcement stress gauges for measuring the soil reaction beneath the cap and the pile bottom as well as the shaft resistance. The test shows that, within a certain duration after loading, the soil reaction beneath the cap and the pile point resistance increase with time; but the shaft resistance decreases. The load distribution among the pile tops in the group tends to be even with time. The shaft resistance redistributes along the pile shaft with time, that is, getting less in the upper part, getting larger in the middle. The redistribution does not tend to stop till the distribution in both upper and middle part becomes to be uniform. The load-bearing conditions of soil beneath the cap of pile group and the variation in time effects with related factors also have been discussed.

Jan 1, 2010

By R. L. Wei

The disturbing influences of pile driving on the surrounding soil mass, including the induced vibration, pore pressure and displacement of soil, were observed during the construction of pile foundations. It is shown that the effects of pile driving in saturated soft clay are tremendous and ought to be concerned attentively.

Jan 1, 2010

By Wang Mingshu

The pile foundation is a kind of advanced foundations in the filled or soft soil. In this paper, through the actural engineering of coal dressing plant of Western Opencast Coal in Fushun built on the mining dump with large diameter pile foundation, the construction method and mechanics analysis of pile are given. Unless it is in following stadge, the stability of pile cannot be lost due to its small rigidity. The analysis shows that pile foundations of large diameter ellipse section can decreased hotizontal displacement to 60% ?70% of that of equal section an in the design of a single pile and a single column, the ellipse pile and manual dig hole are most favourable. So a large amount of concrete can be saved.

Jan 1, 1991