Search Documents

Jan 1, 1991

Jan 1, 2004

By Kaushik Mukherjee

"Malaysian offshore and surrounding region are favorable to the installation of driven piles. During the design phase, pile driveability analysis plays a major role in pile make-up design to suit and selection of the feasible hammer, besides defining acceptance criteria to ensure a certain level of confidence of its fitness for purpose. The accuracy level of driveability analyses depends substantially on the selection of its parameters that best represent the in-situ scenario. The most uncertain of the parameters are those related to the soil model. It is noted in various projects in the region, that the consideration of suitable soil resistance to driving, coupled with soil dynamic parameters, significantly affects driving sequence planning, design, material, hammer selection and most importantly pile acceptance criteria. This is particularly relevant for a region that contains predominantly clayey subsoil resulting in large diameter, long friction piles susceptible to driving disturbances and slow strength recovery. Various researchers suggested suitable dynamic parameters and soil resistance during driving calibrated to specific regions. Regional experience suggests a set of soil degradation and parameters to suit the different stages of driving which is corroborated by pile monitoring records during continuous and delayed driving scenarios. The most sensitive amongst all dynamic soil parameters is the skin damping in clay. Smith’s wave theory approach considers a conservative assumption in selecting the parameters in absence of site-specific data, while a different approach may be adopted based on consistency of the clay for a site where the geotechnical parameters are well defined. This paper summarizes some independent studies on the effects of variations in dynamic parameters and resistance at different stages of driving and suitability of choices of different pile make-up and hammers for an optimum design. Similar experiences, coupled with simulation studies and back-analyses of available driving records suggest a reasonable judgment for the region.INTRODUCTIONFixed structures are generally supported in the in-place condition on a pile foundation those may either be driven or drilled & grouted piles depending on the subsoil. The piles may be driven inside the jacket legs or drilled through individual skirts normally grouped in clusters at the base of each leg. The types of subsoil dealt with in the Peninsular Malaysia and Gulf of Thailand surrounding region are conducive to the installation of driven piles only. The design of an offshore pile is fundamentally the optimization of pile length, size and make-up those are suitable to the requirement and supply. An interactive effort combining aspects related to geotechnical, structural and constructability are required to converge into a feasible, safe and economic solution. Other than the checking of the installation feasibility using a set of hammers in a given environment, driveability analysis is also used to define acceptance criteria for a majority of the offshore piles. Unlike short and end bearing piles in sand/soft rock, the piles in clayey subsoil regime often could not be rested on a dense strata where it could be met by a definite set criteria. Usually a measurement of blow counts determined and defined by driveability analyses forms the acceptance criteria to ensure a certain level of confidence of its fitness for the purpose coupled with an optimum penetration. While softness and uncertainty of the soil strata at target penetration may be resulted in possible overdrive, an unusual delay or the presence of an unidentified cemented layer or a boulder may cause early refusal or underdrive scenario. Hence, accuracy of the investigation, driveabilty study as well as the precautionary measures to avoid delays during driving are of equal importance."

Jan 1, 2015

By Clif Kettle

The paper will detail the design and execution of passive and active settlement control measures, the means adopted to overcome the various physical and operational constraints, and to meet specified allowable settlement criteria. The paper will highlight the close integration between the tunnelling and geotechnical contractors, designer, and Client, and demonstrate how particular practical difficulties were overcome by both the design and the construction methods.

Jan 1, 2008

By Gerald Verbeek, Erick Baziw

"Downhole Seismic Testing (DST) is an important geotechnical testing technique for site characterization as it provides low strain (<10-5) in-situ interval compression (Vp) and shear (Vs) wave velocity estimates. These velocities are determined by obtaining relative arrival times of source waves as they travel through the stratigraphy and are recorded by one or more vertically offset seismic sensors. A challenging aspect of this process is to characterize the seismic data sets to determine the analysis method that will result in the most accurate interval velocity values. This paper introduces an assessment technique which utilizes linearity estimates (i.e., hodograms fitting straight lines) from the polarization analysis in conjunction with crosscorrelation coefficient calculations of the full waveforms as well as the deviation of the source wave frequency spectrum from a desirable bell-shaped curve. The paper will provide an overview of the technique and include some examples of actual data sets where the technique was applied to analyze those data sets.1. INTRODUCTIONIn general terms, Downhole Seismic Testing (DST) such as Seismic Cone Penetration Testing (SCPT) is a geotechnical technique for measuring in-situ shear and compression wave velocities (VS and VP respectively). The main goal in DST is to obtain arrival times as the source wave travels through the soil profile of interest, and from these arrival times the velocities are then calculated. Figure 1 shows a schematic of the typical DST configuration: a seismic source is used to generate a seismic wave train at the ground surface. One or more downhole seismic receivers are used to record the seismic wave train at predefined depth increments. The downhole receiver(s) may be positioned at selected test depths in a borehole or advanced as part of an instrumentation package as in the case of SCPT. When triggered by the seismic source a data recording system records the response of the downhole receiver(s)."

Jan 1, 2017

By Bidjan Ghahreman

A total of 120 micropiles were constructed for foundations of a new selective catalytic reduction (SCR) unit in a coal-fired power plant east of Kansas City, Missouri. Construction was performed under restricted overhead conditions because of the existing facilities. The subsurface profile included about 70 feet of overburden composed of granular fill, stiff to very stiff cohesive material, medium dense sand, and very dense gravel. The bedrock was composed of alternating layers of shale and claystone (weak rock) and limestone (strong rock). It was decided that the bond zone would be entirely in the bedrock. The design rock profile along the bond zone was composed of 10 feet of shale and claystone underlain by 10 feet of limestone, which in turn was underlain by shale and claystone. To achieve the design compression and uplift capacities of 100 tons and 60 tons, respectively, a length of 23 feet was determined for the bond zone. Compression and uplift load tests were performed to verify the design. IBC-2000 elastic line, Decourt (1999) extrapolation, and Chin-Kondner extrapolation were used to interpret the load test results. The interpretation of load test data indicated that both compression and uplift capacities far exceeded the respective design loads. Spring constants of 397 tons per inch (T/in.) (in compression) and 290 T/in. (in uplift) were estimated from load tests at respective design loads. During the compression load test, no sign of creep was observed after the applied load was maintained at the design load (100 tons) for two hours.

Jan 1, 2009

By Min Sunn Ye, Wei Wang, Huawen Xiao, Kai Yao, Fook Hou Lee, Siang Huat Goh

"Previous research have shown that introducing fibers to cement soil mixture is effective in improving the ductility as well as maintaining the strength of cement-treated soil. A good knowledge of stiffness of the improved soil at small strain is essential for realistic predictions of ground movements that may affect adjacent buildings or underlying infrastructure. This paper presents a triaxial system with local strain measurement developed for studying shear modulus degradation of cement treated clay with fibers. Cylinder specimens (70mm diameter by 140mm height) with 50% cement, 100% water, 0% to 1% polypropylene fibers by mass, and 7 days of curing period were used. A local strain measurement system with floating type miniature submersible LVDT is introduced in this paper. Configuration of the mounts including the pin size, length and distance are presented and discussed. Based on the experimental results, a reasonable configuration of the mounts is recommended for fiber reinforced cement treated clay. Results showed that the proposed local strain measurement system is effective for testing the shear modulus degradation of cement treated clay with fibers under both unconfined and confined condition. Comparisons with results from resonant column and bender element tests served to verify the reliability of the local strain measurements using the proposed method.INTRODUCTIONIn many geotechnical engineering problems, the operational strain domain ranges from 10-3% to 10- 1%. A good knowledge of stiffness at small strains is essential for realistic predictions of the ground movements that may affect adjacent buildings or underlying infrastructure. As such, during the last 3 to 4 decades, the importance of using the small strain stiffness of soils for the design of foundation and underground structures has widely been accepted. Triaxial testing has been widely used to study the stress-strain behavior of soil in the laboratory. However, the stiffness obtained from the conventional triaxial apparatus is usually far smaller than those back-calculated from field measurements. This is mainly attributed to the overestimation of axial strains from the external strain measurements, which usually includes compliance effects of the loading and load measuring system as well as sitting, bedding and alignment errors between sample and system (Baldi et al., 1988). The poor resolution of the external strain measurements is another important contribution. Therefore, conventional procedures are inappropriate for small-strain stiffness evaluation due to low accuracy and resolution."

Jan 1, 1900

By Gerald Verbeek, Erick Baziw

Stone columns are used in geotechnical site remediation to increase load-bearing capacity and reduce settlement of foundations. Stone columns also improve slope stability and increase the shear strength of a soil. A very challenging problem is to characterize the in-situ shear wave velocities from data acquired from Downhole Seismic Testing (DST) after the insertion of stone columns. DST is an important geotechnical testing tool for site characterization that provides low strain (<10-5) in-situ interval compression and shear wave velocity estimates, but the postanalysis of seismic data acquired from DST in the presence of stone columns is very challenging due to the resulting complicated in-situ soil conditions. To obtain the right results it is necessary to use an algorithm that incorporates source wave raypath refraction. Starting with the Normal Moveout Seismic Cone Tomographic Testing (NMO-SCTT) algorithm developed some years ago, this paper outlines the modifications and additions made to this NMO-SCTT algorithm to facilitate stone column site characterization. To dramatically reduce the optimal solution space for the estimated interval velocities the paper also described a priori conditions that are applied based on the unique nature of the stone column site conditions.

By Ambarish Ghosh, Rituparna Dey, Indrajit Chowdhury

"In port and harbor facilities, jetties and cargo berth terminals are usually installed on piles that remain partially embedded in soil, while a part of it behaves as columns supporting top deck. Technology in vogue adapts a pseudo static analysis in computer where the top deck including piles are analyzed as an integrated system based on finite element method when the piles are modeled as beam elements, while the soil in which it is embedded is modeled as linear or nonlinear springs. Typical berthing force of the ship is considered as a pseudo static force where the dynamic characteristics of the force is taken into consideration by an equivalent impact factor and little study exists on the actual behavior of these type of piles under the transient shock due to berthing impact. Present paper proposes an analytical solution based on which one can compute the dynamic response of such jetty piles considering shear modulus of soil constant with depth. Considering the solution is analytical in nature no special software is needed and can well be adapted fordesign office practice using generic utility software like MATHCAD, MATLAB etc. that makes theproposed model computationally very efficient.INTRODUCTIONResponse of piles under dynamic load has been an important study in the realms of civil engineering, where significant research has been carried out on its dynamic behavior under harmonic loads like one experienced in a machine foundation or under seismic force.A number of researchers have given solution to this problem like Parmelee et al (1964), Tajimi (1966), Penzien (1970), Novak et al (1974, 1983), Banerjee and Sen (1987), Dobry and Gazetas (1988),Chowdhury and Dasgupta (2008).However, most of these theories are based on piles loaded under harmonic load and valid for long piles where structural failure precedes the soil failure considering the piles are long and flexible."

Jan 1, 2015

Jan 1, 1997

By Meeok Kim, Paul Beljan, Gordon Chen

"Clinton combined sewer overflow storage (CSO) facility project developed by the Department of Water Environment Protection of Onondaga County, New York, is to improve sewer facilities and infrastructure in Syracuse, New York. The below grade facility will provide a storage of untreated stormwater during highflow periods to be treated later, thus reducing CSO discharges to Onondaga Creek.The CSO system consists of three parallel storage tunnels and two end chambers (west and east chambers) as main underground structure. The storage tunnels are about 850 ft. long, 55 ft. wide, 24 ft tall and located 20 ft deep below grade. The chambers, include above access and operation structure, are about 40 to 55 ft. deep and approximately 60 to 100 ft. wide.Kiewit Infrastructure and Weidlinger Associates Inc. developed an alternative approach for the tunnels to meet the facility completion schedule, strict design guide lines and quality control as an environmental and water tight concrete structure for the project. The original design anticipated use of a TBM machine to bore three parallel tunnels between two previously constructed chambers.The alternative design used a three barrel culvert cast-in-place structure in a cut and cover excavation supported by a soil bentonite wall. The SOE along the jet grouted bottom seal provided a ground water cut off as well.The SOE system is specially designed to enhance the quality of culvert CIP structure construction by providing enough space for a full height construction. Also it further reduces the construction time by having the less squarefootage of jet grout installation. The design of tunnel systems is accomplished effectively through the utilization of soil structure interaction using a finite element methodIntroductionTo avoid construction of an additional treatment plant to handle increases in combined sewage flows, the Department of Water Environment Protection of Onondaga opted to construct the Clinton combined sewer overflow storage (CSO) facility.The Clinton CSO facility provides an environmental friendly mitigation method for combined sewer overflows on Onondaga lake which is located in northwest of Syracuse."

Jan 1, 2015

By George Machan

Bitumen coatings have been successfully used to significantly reduce downdrag on piles. Thicker coatings of "soft" bitumens can accommodate downdrag so well that very little downdrag load is transferred to the pile. Many of the case histories describe better than 80 percent downdrag load reduction. Bitumen coatings have been used on several projects in Oregon. On the Mocks Bottom Bridge project (see Reference 1), experimentation and instrumentation confirmed the viability of bitumen coatings and provided insights for design and construction. Subsequent bridge projects have used this information and have raised issues to be resolved.

Jan 1, 1989

By Jim Cook

Arsenal Football Club required the development of a new home stadium in north London, subsequently named the Emirates Stadium. The proposed development comprised a 60,000 seat stadium, with associated facilities and a sports training centre. Described are the foundation solutions and piling construction techniques used, which take into consideration the potential impacts on existing above and below ground railway infrastructure and underground water structures. Methods used by the piling contractor to improve aspects associated with health, safety and quality are also described.

Jan 1, 2008

By Rob Jameson

Micropiles are ideally suited to seismic retrofit applications. Their high tensile and compressive capacity can sustain the large concentrated loads induced during seismic events. Micropiles can be drilled through and grouted into the wide variety of soil and rock materials encountered in seismically active zones, using equipment that operates effectively within existing structures. Micropiles have seen increased acceptance and are now widely specified for retrofit work in the San Francisco Bay Area. While installation equipment and the structural configuration of micropiles have been largely unchanged since the early 1990?s, market forces have pressured both engineers and contractors to continually optimize the cost and performance of seismic upgrades. Instead of the contractor simply developing stronger, stiffer and cheaper micropiles as isolated structural elements in response to a specification, focus has shifted to maximizing the efficiency of micropiles within the overall foundation system. The case history of seismic retrofit project in Berkeley, CA is presented to illustrate the collaboration between designers and drilling specialist which resulted in a structurally efficient and cost effective design. The seismic retrofit program for this 6-story concrete building was developed through careful consideration of the geotechnical and structural mechanisms of resistance, in combination with the deformation response of high capacity micropiles (2670 kN) under ultimate loading conditions. This case history describes the interactive project development emphasizing performance-based design and field testing to optimize the micropile foundations and the overall structural system.

Jan 1, 2008

By Seiji Mizutani, Hirofumi Taguchi, Makoto Yoshida, Hidenori Takahashi, Naotoshi Shinkawa, Kazuo Konishi, Yoshiyuki Morikawa, Masaya Kawata

"The lattice-shaped cement treatment method has been used to improve the seismic performance of liquefied sandy soil in Japan. The efficacy of the method has been confirmed by the huge earthquake in Japan. In the present study, a new method to improve sandy ground by using the lattice-shaped cement treatment method is proposed as a liquefaction countermeasure. It is the floating-type and lattice-shaped cement treatment method, where cement treated soil is not fixed to an un-liquefiable stratum. In this method, a fixed-type structure such as treated soil should be formed at the side of the floating-type treated soil to reduce its lateral displacement. In the study, one-dimensional dynamic response analyses were firstly conducted to confirm the mechanism of the new method. Secondly, a series of centrifuge model tests were performed to demonstrate the effect in a proto-type scale's stress condition. The analyses and model tests confirmed the effect of liquefaction countermeasure of the new method.INTRODUCTIONLiquefaction induced by an earthquake generates sand boiling and ground settlement. Other problems have also been reported, including a decrease in bearing capacity and an increase in the horizontal earth pressure against retaining walls. To prevent these problems caused by liquefaction of the ground, various countermeasures have been proposed, such as cement deep mixing and high-pressure jet mixing methods. These methods have the big advantage of being applicable to ground that contains soil with a fine-grain fraction. Furthermore, the unnecessary displacement caused by the construction can be reduced. In Japan, a lattice-shaped cement-treatment method has frequently been used at many construction sites to prevent liquefaction, where cement-treated piles are intersected to form a lattice, as shown in Fig. 1. The lattice-shaped walls can reduce the shear stress generated by an earthquake, restricting the liquefaction at that location. However, the construction cost of the cement treatment is relatively high compared to other methods such as the sand compaction pile (SCP) method, and needs to be reduced. Therefore, decreasing the total volume of the cement treatment is necessary to reduce the construction cost."

Jan 1, 2015

Jan 1, 1993

By Joel Moskowitz, Jan Cermak

"New York City has unique geologic conditions which must be considered when designing pile foundations. Where shallow foundations are not feasible, the City's subsurface conditions require a variety of deep foundation systems, ranging from high capacity rock socketed piles, to piles end-bearing on bedrock, to friction piles bearing in alluvial or glacial deposits. Pile load testing is essential in confirming pile capacities as pile analyses include assumptions on soil and soil-pile response, and pile driving equipment. Load test results must be interpreted to estimate the long-term pile behavior. Except for lightly loaded driven piles, the New York City Building Code (the Code) requires that pile capacities be confirmed by static load testing. The Code provides the number of static load tests required, test procedures, and acceptance criteria. In the last few decades, methods other than static load testing have been developed including dynamic and rapid (pseudo-static) load tests. Recently, those methods have also been employed on several projects in New York City. The traditional approach to pile load testing in New York City is discussed herein including engineering involved in the analyses of test data with examples. In addition, several projects which included non-static load testing are discussed INTRODUCTIONPile load testing complements the subsurface information and pile design by providing further data on pile-soil interaction for the selected pile type and installation method. Traditional approaches to pile load testing in New York City involve static load tests to verify the design capacity of the piles for a given minimum factor of safety.In the late 1950's, Dr. Phillip C. Rutledge summarized his views on the philosophy of pile foundations in an unpublished, in-house document. He viewed pile foundations as good illustrations of pertinent and impertinent aspects of geotechnical engineering. In the analyses of piles he divided engineering into four general types:(a) Theoretical engineering in which decisions are made based on theoretical analyses. This represents ideal engineering, in which all factors affecting the pile design are well established or, at least, few simplifying assumptions with known effects on the analyses are made."

Jan 1, 2005

By Frank Rausche

Why testing What tests can be done Dynamic load testing Loading device Measurements Analysis Examples

Jan 1, 2001

By Karen J. Dawson, Francisco Johnson

"Pressure-grouted high strength helical displacement piles are a recently developed pile type that can be useful in conditions where noise or vibrations must be low or where access or clearance is limited. However, there is no information in the literature that can be used to estimate the soil resistance of these piles or production rates. To fill this information need, this paper presents a New Jersey installation case history and the results of static axial and lateral load tests on both pressure-grouted and ungrouted high strength helical piles at the case history site and trial installation locations in New Jersey and Washington State. Piles between 25 and 50 feet long comprised of steel shaft diameters of 4.5, 5.5, and 7 inches with equivalent grout column diameters ranging from 12 to 22 inches were tested. Lateral loads of up to 100 kips and axial compression loads of up to 700 kips were applied. The results of the load tests are compared to predictions of lateral deformation and axial resistance.INTRODUCTIONHelical piles have long been recognized as a useful foundation type in situations where noise and vibrations must be limited, or where there are access or clearance restrictions. Relatively well-documented design methods and torque to capacity correlations have been developed for the most commonly used helical piles, which are relatively small (typically shafts of 6 inches or less) with corresponding low load carrying resistance.With the increased need to construct in congested urban environments, there is incentive to develop helical piles with higher axial resistance. Seismic and other loading conditions also require lateral resistance, which is low for the typically small helical pile shafts. One method of increasing the soil resistance, both axially and laterally and at relatively low cost, is to place grout around the shaft. Injecting the grout under pressure through the hollow helical pipe section and out a grout port or ports located near the toe of the pile has the potential to increase the pile resistance significantly above that which can be achieve by gravity grouting. Not only does the pressurized grout push out against the surrounding soil, but the rotating helix helps to distribute the grout laterally. Unfortunately, little information is available in the literature to help designers estimate the resistance of grouted helical piles in general and none is available regarding pressuregrouted helical piles."

Jan 1, 2016

By Ground Improvement Committee

The evaluation of earthquake-induced liquefaction has become a routine part of geotechnical engineering design. For a given project, if an analysis identifies a potential for liquefaction and the consequences of liquefaction are deemed unacceptable, then some form of hazard mitigation is required. Mitigation efforts may consist of removing the liquefiable soils, bypassing the liquefiable soils with deep foundations, structurally accommodating the deformations or strength loss caused by liquefaction, or preventing the onset of liquefaction through ground improvement. The fundamental ground improvement mechanisms for liquefaction mitigation include densification, drainage, and reinforcement. When evaluating, recommending and specifying various ground improvement methods for liquefaction mitigation, practitioners should understand the fundamental mechanics involved and applicability and limitations of the various methods. The DFI Ground Improvement Committee offers a review of the fundamental mechanics and commentary on the applicability and limitations of each method to provide clarity and guidance on the issues related to ground improvement for liquefaction mitigation.

Aug 1, 2013