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By Gordon Chen

As part of a value engineering envisioned by East Coast Slurry, Weidlinger Associates, Inc. designed a unique elliptical slurry wall cofferdam for construction of the 65 ft. deep MWRA North Dorchester Pump Station. A conventional rectangle cofferdam with multiple levels of bracing would have been time consuming and costly and imposed a significant obstruction to the pump station construction. A circular slurry wall, while eliminating the bracings, conflicted with adjacent structures and required excessive backfilling around the final pump station structure. The ellipse shaped cofferdam fit the needs of the project well; however, it created a significant design challenge without the use of bracings. Unlike a circular cofferdam which primarily only has hoop stresses, the ellipse still has to be designed for horizontal bending moments in each panel because of the non-axial symmetric conditions. The more eccentric the cofferdam shape; the higher the horizontal bending. The challenge was to develop a three dimensional finite element model that could analyze both the hoop stresses and horizontal bending stresses above and below the bottom of excavation induced by soil and water pressure and unbalanced construction surcharge loads. This paper discusses the techniques used to model the soils and structure interactions and results of stresses on this challenging unbraced configuration.

Jan 1, 2010

By Ramdane Bahar

The new Algiers airport building is a reinforced concrete building of more than 80 thousand square meters of floor slabs. It is located at Dar-EI-Beida, near the old passenger terminal, about 20 km east of Algiers. The project is designed to receive about six millions passengers annually and leaves the possibility of future extension. Due to the presence of a top layer of compressible soil and great concentrated loads transmitted to the foundations, the building is to be founded on 1730 bored piles of 1.2 meter diameter varying in length between 14 and 28 m. Construction work started in 1986 and was interrupted in 1996 due to financial difficulties when the structure was almost complete. The structure was left unattended for more than three years without any weatherproofing and in 1999 a new firm was appointed to complete the work and hence an evaluation of the existing structure was necessary. This paper describes and discusses the foundation design, construction supervision, site quality control and assessment by the parallel seismic method of the deep foundations built in cohesive soils. The variation in soil conditions and identified geotechnical and hydrogeological problems associated with the development of the area, required a thorough knowledge of the soil conditions. A variety of tests, involving more than 200 locations, were carried out. The ground investigation, pile tests as well as different problems encountered during piles construction, are presented.

Jan 1, 2002

By Saba Mohan

For the three full-scale pile installations, two different high-energy hydraulic hammers were selected for the installation. However, these hammers may not have sufficient energy to drive these large diameter piles at their ultimate capacity following long-term set-up. Nevertheless, these hammers were selected because, soil plug behavior, the generation of excess pore pressures and remolding of soil during driving were expected to reduce the shaft and end bearing resistance, and therefore reduce the energy required to drive these piles to design penetration. Data collected during continuous installation driving and after a series of re-strikes at different set-up times ranging from 1 to 33 days were used as input data for CAPWAP analyses. These results were used to estimate the soil resistance along the pile length and at the toe of the pile, and the soil pile set-up behavior. Validity of the procedures used to predict the soil resistance to driving and predicted blow counts were verified with the field observed blow counts and the energy that was delivered to the pile. Based on combined CAPWAP analyses, the soil pile set-up with time was predicted.

Jan 1, 2002

By Daniel Ruffing, Charlie Krug

In recent years, the chain-style trencher has been proven a valuable tool for installing vertical walls on challenging sites where conventional methods may be less desirable. Like many tools, trenchers are most effective when used with the right application. Trenchers are commonly used for applications that could also be completed with conventional slurry trenching; low-permeability cutoff walls, collection trenches and permeable reactive barriers (PRBs). Drawing from a wealth of experience with conventional slurry trenching and the trencher, this paper compares and contrasts the technical considerations, treatability, installation, performance, and lessons learned for recent projects.

By Michael Oakland

This paper will discuss the design analysis of sheet pile cofferdams for static and dynamic blast loads. Following construction of the new Willis Avenue Bridge across the East River between Brooklyn and Manhattan, in-river piers No. 9 and No. 10 from the former bridge were demolished, partially by explosive charges. The blast at Pier 10 was conducted first and though the demolition charge was relatively small, it gave confidence that the sheeting could be designed to resist the blast load. This paper primarily summarizes our analysis and performance of a sheet pile cofferdam at Pier 9 used to withstand the larger blast loads, contain the blast debris, and allow excavation of the pier below the existing river bed mudline. The program NLFlex was used to predict stresses and deformations of the cofferdams under dynamic blast loads, using simplified equations to estimate the underwater blast pressures. Specifically, the analysis focused on the stresses in the struts, waler beam, sheet pile interlocks and connection of the sheeting to the waler beam. Design included allowing plastic deformations and limited rupture of the sheet pile interlocks under the blast loading. Comparisons are made between stresses assessed by the dynamic finite element modeling and empirical relationships used within the industry. The performance of the system after the actual blast is discussed as well as details of the performance of welded vs. bolted connections within the system.

By John Mould, Gordon Chen, Michael Oakland, William McElwee

"This paper will discuss the design analysis of sheet pile cofferdams for static and dynamic blast loads. Following construction of the new Willis Avenue Bridge across the East River between Brooklyn and Manhattan, in-river piers No. 9 and No. 10 from the former bridge were demolished, partially by explosive charges. The blast at Pier 10 was conducted first and though the demolition charge was relatively small, it gave confidence that the sheeting could be designed to resist the blast load. This paper primarily summarizes our analysis and performance of a sheet pile cofferdam at Pier 9 used to withstand the larger blast loads, contain the blast debris, and allow excavation of the pier below the existing river bed mudline. The program NLFlex was used to predict stresses and deformations of the cofferdams under dynamic blast loads, using simplified equations to estimate the underwater blast pressures. Specifically, the analysis focused on the stresses in the struts, waler beam, sheet pile interlocks and connection of the sheeting to the waler beam. Design included allowing plastic deformations and limited rupture of the sheet pile interlocks under the blast loading. Comparisons are made between stresses assessed by the dynamic finite element modeling and empirical relationships used within the industry. The performance of the system after the actual blast is discussed as well as details of the performance of welded vs. bolted connections within the system. IntroductionThe Willis Avenue Bridge is one of the major access ways from the Bronx into Manhattan. The location is shown on Figure 1. The original bridge constructed in 1901 was a swing bridge over the East River. The bridge was in disrepair and outdated with regards to its ability to handle the flow of traffic resulting in numerousaccidents.In 2007, Kiewit Constructors Inc./Weeks Marine, Inc., A Joint Venture was selected to construct a replacement bridge. The $612 million project included construction of a new bridge just to the south of the original bridge. The most notable aspect of the construction was floating and lifting the new 350 ft. long swing span in place as a single piece. However, another significant challenge was using blasting to demolish two of the abandoned piers which were within the East River. The blast would be near existing structures in both Manhattan and Brooklyn and would be within 30 ft. of the new bridge."

Jan 1, 2017

By George Filz, Peter R. Cali

"Unnecessarily restrictive specifications could be limiting the cost effectiveness of deep mixing (DM) applications and therefore limiting use of DM on projects where there are other options. Excessively restrictive standards demanded for strength and permeability certainly increase contractors’ bid prices, and costing the owners and, in the case of Government projects, the taxpayers more than necessary. Yet, lax or ineffective specifications often exist for some vital components of the quality assurance and quality control. In this paper, specifications for key elements of DM design and construction are examined. Recommendations are made to improve and streamline DM specifications to better serve the common objective of constructing a safe and cost effective ground improvement project.INTRODUCTIONSpecifications should, at their best, convey the project design requirements and provide clear direction to the contractor regarding requirements for submittals, materials, execution, measurement, schedule, and other aspects as necessary. The specifications should not be overly conservative, restrictive or ambiguous, and they absolutely should not be deficient in measurement of quality. Guide specifications or recycled sections from previous projects often form the template for new project specifications. But standards that appear in guide specifications or from former successful construction should be critically scrutinized by the designer for relevance before using the copy/paste functions of the specifications writer’s keyboard. Because work does not always go as smoothly as planned, specifications for remediation of non-compliant construction should be clearly stated and enforced. Often, non-compliancy is reviewed after-the-fact and deemed to have met the design intent, indicating that either the specifications were too restrictive or the enforcement too weak.The Federal Highway Administration Design Manual: Deep Mixing for Embankment and Foundation Support, October 2013, was written by a panel of DM expert design practitioners and contractors. Guide specifications are included as Appendix C of the FHWA manual. Those guide specifications have been updated in the deep mixing section of the www.GeoTechTools.org website, and the updated specifications represent the most complete and authoritative compilation published to date. Although the specifications for DM at www.GeoTechTools.org are current and complete, and they portray the state-ofthe- practice, they too must be modified to fit specific DM applications, project needs, and site conditions. The keys to a good set of specifications are to prescribe construction only to the level that is required to meet the design intent, to require appropriate quality control and quality assurance (QC/ QA) activities, and to clearly address remedial measures required for non-compliant work."

Jan 1, 2015

By Fei-chiu Huang

A 17-acre landslide occurred in February 2001, on a slope below Via Bellota in the City of San Clemente, California. Three homes were destroyed and many others placed in jeopardy. The landslide, involving portions of five separate developments, continued to move significantly in the years following. Litigation ensued among the affected parties, and investigations continued through 2007. A mediated repair resolution was ultimately reached among the parties. The agreed upon repair consists of a multi-million dollar stabilization program that included grading, drainage, and structural systems. Part of the construction cost was offset by creating 4 new ocean view custom lots and 20 new mobile home lots. The landslide repair and slope stabilization design involved removal and replacement of portions of the landslide debris and construction of buttress and stabilization fills as well as installation of 74 shear pins in two rows. The shear pins were designed as 4-foot diameter by 50 feet in length and incorporated continuous W30x211 wide flange steel. The shear pins were designed to be installed 25 feet above the slide plane and 25 feet below the slide plane at each location. Construction of the 74 shear pins was initiated in 2008 and completed in 2009. Four-foot diameter holes were drilled by utilizing a truck-mounted, flight-auger-style drilling rig with a 4-foot diameter solid-flight auger. Prior to the installation of the shear pins, an engineering geologist downhole logged strategically selected holes to further evaluate the actual slide plane elevations. The wide flange steel shear pins were then lowered to the desired elevations and encased within 4,500 psi, Type V, 0.45 maximum water/cement ratio concrete. Inclinometers installed within four pin shafts and behind the pin rows indicated performance in accordance with the design. Slight to non-perceivable shear displacement was measured which mobilized the intended capacity at the monitored shear pins. No excessive slope movement was detected at any of the inclinometer locations during or after the construction period. Actual shear displacement of the steel wide flange elements was less than the movement anticipated before shear pin installation.

Jan 1, 2010

By Helen Ahnberg

The scope of the present paper is limited to report the experimental evidence and not for describing the analytical assumptions. However, the idea behind the experimental program is that the deterioration may be caused by the leaching of Ca from the treated soil to surrounding soil or water driven by the difference in the Ca ion concentration. As a consequence of Ca leaching, it may be natural to expect the expansion of micro void space within the treated soil. In a saturated condition, the water inflow into the treated soil may accompany the leaching phenomenon. We measured the water content within the treated soil. But there is not much difference in water content within the soil.

Feb 10, 2003

By Wang Lushuang

This thesis is devoted to the research of the interaction between pile and foundation soil by boundary element method (BEM for short). The interaction is simulated by the interaction between two different elastic mediums. The foundation soil is simulated by the two-dimensional elastic half-plane, and the pile by the two-dimensional elastic finite plane. Therefore, the calculating models made by the paper's author would come more closed to the actual conditions. The elastic behaviour of the interaction between pile and soil, and the whole course of pile ultimate load are analysed in the thesis, and the relevant applied computer programs "BEME", "BEMPA" are designed by the paper's author. The bearing power of single pile can be worked out by the program "BEMPA", it has compared with staic loading tests of pile, and the results are in conformity to actual conditions. So it can be drawn that the BEM for studying on interaction between pile and foundation soil made in the thesis is more simple, more precise and more practical in actual project.

Jan 1, 1991

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 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 Makarand G. Khare

Though the phenomenon of dragload is known for many decades, there is a lack of clear guidelines to evaluate the amount of dragload. The development of dragload depends on relative movement between pile and surrounding soil which is a complex phenomenon and requires a detailed numerical analysis. Bitumen layer has been used in the past with varying degree of success in reducing the dragload but the reduction appears to depend on number of parameters. No procedure is available in literature to estimate the dragload when a slip layer is applied on pile surface. This paper investigates performance of two commercially available bituminous coats to reduce the negative skin friction on pile. Direct shear test apparatus was used to model the interface friction between soil and coated pile surface. The lower half of direct shear box was replaced with either a concrete block or a mild steel block representing pile surface. Two types of bituminous coats namely Shalikote and bitumen having penetration value of 30-40 were evaluated in this study. Shearing resistance of pile material-coat-soil is found to be influenced by normal stress, coat thickness, and rate of shear. Laboratory results are compared with published field data where coated and uncoated piles have been load tested.

Jan 1, 2006

By P. Srinivasulu

The popular theoretical models used for assessing the dynamic behaviour of piles under vertical and lateral excitations are critically reviewed. An experimental study is presented on model piles with varying slenderness ratios. The theoretically evaluated and experimentally deduced natural frequencies and resonant amplitudes of the test pile-soil system are compared. The dynamic stiffness and damping are seen to increase with increasing slenderness of piles. Further, the damping yielded by the theory is found to be on the unconservative side.

Jan 1, 1996

By L. D. Johnson

12 groups of 12 precast prestressed (PCPS) piles were driven in the lagoon of Kwajalein Island to support a dry dock. Pre-construction investigation of the calcareous coral sands and static pile loeid tests were performed to determine if the 7.9 by 7.9 cm (20 by 20 inches) by 26 m (85 ft) long PCPS piles embedded to a depth of 16 m (53 ft) would adequately support the dry dock. Driving records for production piles indicated that the blowcounts of the piles at the fincil embedment depth became substantially less than expected as piles wssre driven further toward the lagoon end of the dry dock and decreased to as low as 2 blows/ft. A supplemental investigation that included a static load test on a production pile, the driving of an indicator pile, and restrikes indicated that the pile foundation has adequate bearing capacity. The observed bearing capacity appears to be effected by several mechanisms including breakdown of cementation between sand particles, densification of the sands during driving, and dissipation of excess pore pressures and recementation after driving.

Jan 1, 1993

By Mousaab Majar, Nikolaus Schneider

The technical challenges for accurate drilling positions increase with deep underground structures in inner city areas. Designed for jet grouting, specific sensors have been developed to record the alignment of rods during drilling by integrating microchips into the drilling rods. By feeding the rod with constant electric current, microchips, integrated in special couplings, can be read during the drilling process and tracked on monitors installed in the operator’s cockpit. The orientation for the drilling rod is provided by magnetic points and a compass, positioned above ground on the drilling rig. In combination with asymmetric drilling bits, it is now possible to steer the drilling hole to predetermined positions to compensate for deviations in deep bores. This type of drilling rod for jet grouting has been used in Berlin since summer 2019.

May 1, 2022

By A. Le Kouby

We present in this paper the results of a parametric study carried out in a calibration chamber on instrumented model piles. The aim is to point out group effect on piles within a group through their resulting shaft friction and tip resistance. The methodology relies on the study of the influence of adjacent piles on a "reference" pile. The soil used is a silica sand (Fontainebleau sand). The influence of parameters like pile spacing, number of piles and installation order are evaluated. The results show a positive effect on shaft friction of the group effect and a negative effect on tip resistance. Efficiency factors are defined in order to have a better view on the parameters influencing the response of the pile within a group.

Jan 1, 2006

By Manish Kumar

One of the recent advances in the field of testing of concrete piles is the Non-Destructive testing (NDT) of piles. This paper deals with a specific project where this technique was employed along with an extensive program of conventional testing methods to cross check the results. Conventional testing of the Bored, cast-in-situ piles involved taking full length concrete cores from piles to check physical properties such as core recovery, RQD, crushing strength and density of concrete. Additionally, a number of questionable piles were exposed and inspected and actual load tests were performed on selected piles. Concrete pour cards were used to compare actual Vs theoretical consumption of concrete. A direct comparison of the conclusions drawn from both these testing methods provided an excellent opportunity to better understand the intricacies of NDT technique. The study undertaken clearly indicated a need for developing clear guidelines and specifications for the use of this method of non-destructive testing of piles before the .method can be accepted as a useful quality control tool at the construction sites.

Jan 1, 1996

By Christian Hoyme, Jochen Maurer, Hans Regler

Up to today, it has been very difficult to obtain qualitative and quantitative information about the status and production process of a construction site. It is becoming more and more important to be able to analyze this process so as to notice bottlenecks and interruptions on the site early on. The high costs of each shift in special foundation industry mean that making the wrong decision and/or interruptions can put the financial result at risk. Previously, keeping reliable data meant manual process documentation. This was done either by an additional staff member (incurring high additional costs for training, education, etc.) or by the equipment operators. The latter is critical, because they have to initiate every process step change, leaving no time to log data separately. Studies have shown that there are considerable deviations from the actual process steps. In this paper, a seamless, automated method will be introduced to analyze the construction process. This method recognizes each process step from the equipment data. The main purpose of the data recorded by the piling rig is the need of quality reports and now basis for the presented analysis. Here, a method was successfully transferred from theoretical computer science (compiler construction field) to find application for process recognition. Because the execution of works in special foundation construction can always be defined sequentially and therefore also practiced sequentially, recognition can occur step-by-step. Our method always recognizes the next step, so it does not have to monitor as much data at the same time. Individual trigger points are easier to define. Unlike solutions that are based on a global approach and allocate suitable process steps to data patterns, thereby also creating gaps, the presented method is always seamless. Furthermore, this method can be applied regardless of time or location provided that the necessary machine data is available, which is normally the case with production data logging. This means that construction sites even from the past can also be analyzed and the results used for comparisons. The first results from the analysis of a complete continuous flight augering (CFA piles) installation process of a construction site will be presented.

Sep 8, 2021

By E. Ulrich Klotz

It is difficult to predict accurately the capacity of driven piles in sand. In practice, this uncer­tainty either leads to conservative designs if the capacity is under-predicted, or worse, if the capacity is over-predicted, it can lead to severe foundation problems. One significant possible cause of the problem is that currently available semi-empirical design methods do not capture the fundamental mechanisms that govern the load capacity of driven piles in sands. As part of a recent research project at City University centrifuge tests on a driven model pile in sands have been undertaken. A fully instrumented model pile was constructed and pushed into samples of quartz and carbonate sand thus covering a wide range of mineralogies. Tri-axial tests were used to determine the fundamental patterns of behavior of the sands. This allowed a general framework to be established, in which the in situ stress:volume relationship is shown to govern the capacity of the pile. The paper sets out with a brief introduction of the experimental techniques used in the study. The results of the pile tests are discussed in detail with particular attention given to distribution of the radial stresses along the pile shaft. Existing design methods for piles in sand are then discussed in the light of the new understanding gained from the research, highlighting their deficiencies and suggesting an improved approach.

Jan 1, 2002