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By J. Pei

The studies of dynamic measurements using stress wave theory has commenced in China. This paper introduces some practical experiences using "CASE method" in Shanghai showing applications of dynamic measurement to determine ultimate bearing capacity of pile, the change of capacity due to set up, determining the optimum bearing layer during pile driving, the efficiency of hammer system and integrity of pile and discussions of method concered.

Jan 1, 2010

By George G. Goble

In the middle of the nineteenth century, the dynamic formula appeared as a description of pile penetration during impact driving. The simplicity of use of the formula combined with the power of the energy concepts behind the formula caused it to be quickly accepted and integrated into practice. Dynamic formula had been in use for 100 years when the Wave Equation computer programs first appeared. With that long experience it is not surprising that the formula continued to be used and were only slowly abandoned. The Wave Equation offers many advantages over the various formula but it does not offer a clear sense of physical understanding of pile driving that is available with the formula. Large amounts of numbers are generated but often it is difficult or impossible to gain a physical understanding of the results or a feeling for the importance of the various parameters. The question that the Wave Equation user has is, "What will happen if I use a larger drive cap (or change any other item of equipment)?" In this paper, I will attempt to explain pile driving using elementary wave propagation theory. However, the presentation will not depend on any higher mathematics. With the use of wave mechanics, it is possible to explain driving characteristics that cannot be handled with the energy formula.

Jan 1, 1995

By Lianyang Zhang

For optimal design of rock socketed shafts used to support axial loading, it is important to predict the end bearing capacity. The existing empirical methods for determining the end bearing capacity of rock socketed shafts use the empirical relations between the end bearing capacity, qmax, and the unconfined compressive strength of intact rock, sc. Since rock socketed shafts are supported by the rock mass (both intact rock blocks and discontinuities separating them) not just the intact rock, one should consider not only the intact rock properties but also the influence of discontinuities when determining the end bearing capacity. Although the effect of discontinuities may have been implicitly (partially) included in the empirical relations derived from the results of load tests, it is not clear how big the effect is and how much of it has been included. In this paper, a database consisting of 50 test shafts, 25 of which contain the RQD (rock quality designation) value, is developed. Using the database, the applicability of the existing empirical relations is evaluated and two new empirical relations between the end bearing capacity, qmax, and the unconfined compressive strength of rock mass, scm, are derived. The new empirical relations explicitly consider the effect of discontinuities by using scm which is directly related to RQD. Finally, an example is presented to demonstrate the application of the newly derived relations.

Jan 1, 2008

By Thomas C. Anderson

Thirty-four retaining walls are part of the $46 million upgrade of a 1942 depressed highway in Highland Park, Michigan near Detroit. This project will close a missing link between two newer roadways, I-75 and the John Lodge Freeway. The existing 75 ft. wide, six lane Davison Freeway is being replaced by a eight to ten lane, 200 ft. wide depressed highway in a limited right of way. The highway will be 20-25 ft. deep and 1.5 miles long. A design/build decision by the Michigan DOT saved about 37% of the engineers estimated cost of $19 million for the walls. The successful pre-qualified specialty contractor utilized an innovative solution for the walls consisting of tiedback/cantilevered walls on the north side and mechanically stabilized earth walls on the south side. All of the walls have an identical cast-in-place architectural facing.

Jan 1, 1999

By Josef K. Alter

Crosshole Sonic Logging (CSL) of drilled shafts requires 1.5-in (38-mm) or 2-in (51-mm) I.D. sonic access tubes to be installed inside the steel reinforcement cage. The sonic access tubes do not contribute to the structural capacity of the drilled shaft. The proposed use of Ischebeck TITAN T73/56 CSL/Hollow Threaded Rebar for Cross Hole Sonic Logging Access Tubes Combined with Longitudinal Concrete Reinforcing in Drilled Shafts (patent pending) is discussed as an alternative method of construction and CSL probe access. The T73/56 hollow threaded rebar/sonic access tube performs as a high strength rebar while at the same time creating a 2.2-in (56-mm) I.D. sonic access tube. The deformed high strength hollow bar provides better adhesion to concrete thus reducing the problem of debonding associated with smooth PVC and steel pipe. A cost comparison using conventional rebar with added sonic access tubes is discussed. The use of T73/56 CSL/Hollow Threaded Rebar as a value engineering alternative can reduce both material and labor costs for drilled shaft construction and can provide an advantage where anchor bolt cages and longitudinal reinforcing create congestion.

Jan 1, 2011

By Balu E. George, Subhadeep Banerjee, Shailesh R. Gandhi

"A three-dimensional analysis of laterally loaded helical piles installed in cohesionless soil is presented. Finite Element Analysis was conducted using commercially available Plaxis 3D AE version, assuming Mohr-Coulomb failure for soil. Pile is modelled as plate elements with a single helical blade attached to a hollow shaft. The ultimate load for various configurations is examined considering deformation criteria. The Bending Moment distribution and maximum lateral deflection are also discussed. It was observed that the ultimate lateral load carrying capacity increased by presence of helical blade and the maximum deflection also got reduced. The diameter of the helical blade was found to have significant effect on the lateral deflection, maximum bending moment and the ultimate load. However, the observations from the study suggest that the presence of helical blade seizes to produce considerable effect after a certain depth. Difference in failure pattern with regard to the distribution of soil resistance observed for different geometries considered for numerical analysis are also touched upon.INTRODUCTIONHelical piles or screw anchor piles have gained popularity due to fast installation, instant use, and other advantages over the traditional piles. They are usually used to support structures like solar panels, light houses, and other light structures which are subjected to uplift loads. However, such structures are often subjected to significant lateral loads as well. Under lateral loads, the response of helical piles can be different from that of a conventional pile due to the presence of the bearing provided by the helical blade. However, the proper design remains a concern due to lack of work carried out on the lateral capacity of helical piles.The lateral performance of helical piles is significant because they can act as efficient alternative to conventional piling systems in many applications.The lateral load capacity of screw anchor piles with different number of helices were examined by Mittal et al. (2010) by experiments in sand. They found that the lateral load capacity of piles increases with addition of helical blades. Prasad and Rao (1996) examined the lateral capacity of helical piles in clay by experiments on model piles and found that the lateral capacity of helical piles were more than that of the straight shaft piles. It was observed that the lateral capacity increase with embedment depth and shear strength of soil. Sakr (2009) studied lateral performance of two section helical piles in soft soil. The investigation by Prasad and Chari (1999) reported that the pressure distribution across the diameter is not uniform for circular piles, but it is maximum at the centre and almost zero at the two edges.Puri et al. (1984) after conducting model tests on single-helix, two-helix, and three-helix anchors installed in sand, proposed a mathematical model that was fashioned after Matlock and Reese’s elastic theory model. Elkasabgy and Naggar (2015) investigated he lateral performance of full scale large capacity helical piles in structured cohesive soils and reported the modulus of sub-grade reaction to be non linear."

Jan 1, 2017

By Aaron S. Bradshaw, Ryan M. Coulson

The offshore wind industry in the United States is slowly emerging with the recent construction of the first offshore wind farm located off the coast of Rhode Island. The turbines at the Block Island wind farm are supported by piled jacket structures, which historically have been used for much heavier oil and gas platforms. Offshore wind turbines have unique design requirements and the axial behavior of the supporting piles under cyclic loading is important to design. Cyclic degradation along the pile shaft can affect the capacity, deformation, and stiffness performance of the foundation and of the structure as a whole. This paper proposes a strain-based approach to estimate the fatigue (or endurance) limit of a cyclically loaded pile that may be applicable to long-term service loading. The method is applied to an existing load test dataset and the analysis results appear consistent with the observed pile response. INTRODUCTION The demand for renewable energy has been increasing in recent decades and wind power has seen a dramatic increase in popularity. In Europe, as of 2017 there were 4,149 grid-connected offshore wind turbines across 11 countries (windeurope.org), many of which are supported on monopile foundations. It wasn’t until recently (2016) that the first offshore wind farm was constructed in the United States off the coast of Block Island, Rhode Island. The project included 5 piled jacket structures founded in terminal moraine deposits. Future offshore wind development along the U.S. eastern seaboard could possibly utilize jacket structures in granular foundation soils. Loads from wave, wind, and turbine rotation induce cyclic loads on the foundation that have on the order of 108 loading cycles over the service life on the structure (Schneider and Senders 2010). Turbines located along the U.S. east coast have the added risk of hurricanes. As shown in Figure 1a, the lateral loads on a jacket structure are transferred primarily as axial compressive and possibly tensile loads on the supporting piles depending on the weight of the structure. The friction along the shaft of the pile can be prone to cyclic degradation, leading to reduced pile capacity and stiffness, and increased deformations. An offshore wind turbine foundation must be designed for a variety of limit states including ultimate, serviceability, and fatigue limit states. For a jacket structure this would include an analysis of the ultimate axial pile capacity, axial stiffness, and axial deformations, all of which can be affected by cyclic loading both under extreme (i.e. storm) conditions as well as long-term service conditions. Axial pile stiffness is needed, for example, to estimate the natural frequencies of the structure as a whole and to assess dynamic and fatigue loads. The structure must be designed such that its natural frequency remains outside the loading frequencies of the waves and turbine blade passing frequencies to avoid resonance. Therefore, prediction of the axial response of the piles is important to the design of these structures.

Jan 1, 2018

By George Mylonakis

The curvatures and subsequent bending imposed to piles by the surrounding soil during the passage of strong seismic waves is studied. This type of bending develops even in the absence of a superstructure and is referred to as "kinematic bending", to distinguish it from bending imposed to piles by loads generated from the inertia of the superstructure ("inertial bending"). Although kinematic loading may be severe in the presence of sharp stiffness discontinuities in the profile and may lead to damage, it has received little attention by engineers. The scope of the paper is twofold: (i) to discuss some fundamental aspects of seismic pile bending, and (ii) to review some existing design methods. To this end, a dimensionless bending strain parameter (instead of the more commonly used bending moment), and a strain transmissibility function relating pile bending strain and corresponding soil shear strain are introduced. Numerical examples are also presented.

Jan 1, 2002

By T. Soejima

In recent years, there has been a tendency in the field of foundation piling works to utilize piles of greater bearing capacity in order to meet increasing height and weight of modern building as a means of saving of piling cost. To satisfy these requirement, a new technique for large diameter bell bottom cast-in-place piling has been developed utilizing multi-head reverse circulation drilling system.

Jan 1, 2010

By A. Holeyman

The displacement compaction piles described in the paper are installed using a heavy casing or tube and an internal drop hammer. The casing which initially is closed at the bottom by a sand plug displaces the surrounding soil during the driving. Additional sand is rammed down through the casing during the extraction of the casing. The applications and limitations of the method are reviewed in the paper. The importance of checking the sand compaction piles during and after the installation is stressed. Indications of the compaction of the surrounding soil during the driving can be obtained by comparing the initial and the redriving logs of the casing as well as from the volume of sand added. A method to estimate the increase of the mean cone resistance as measured by CPT tests in sandy and silty soils is presented. The governing parameters are the volume of the added sand, the granulometric index and the initial cone resistance.

Jan 1, 2010

By V. M. Troughton

Large diameter bored piles with grouted bases have been adopted for the foundations of the majority of the buildings at Canary Wharf in London's Docklands, including a deep basement car park. The piles are founded in the Thanet Sand which forms part of London's aquifer where water levels are reported to be slowly rising. A special pile test has been carried out to determine the effects of both the basement excavation and a possible long term rise in the groundwater level on the performance of base grouted piles. These effects were simulated by injecting water around the pile toe and thus reducing the vertical effective stress. In this paper the test layout and procedures are described and the results are presented. The test results showed that the reduction in pile base resistance under increased water pressures was less than predicted by conventional design methods based on vertical effective stress. The end bearing resistance was found to be proportional to the mean effective stress.

Jan 1, 1989

By Xiong Houjin

In the excavation works of some deep foundation pits within the boundaries of Guang­dong Province of China, though some measures, such as steel sheet piles, diaphragm walls, etc. were taken to protect the walls, the construction of the excavation works was often accompanied by damage of buildings and public facilities, surface settelment. sand boil and collapse of piles. When these happened, only chemical grouting could be used as the most efficient measure for rushing to deal with or rescue the emergencies. Besides, the application of chemical grouting protection wall technique also palys a very important role under the geologic conditions of the coastal areas of Guangdong Province, when applied in the mucky oystershell layer wealthy in water and the deep mud layer, it can not only achieve good results, but also reduce the cost significantly. In this paper, we discuss the water-tight and earth retaining functions of chemical grouting protection wall in weak formation, and introduce the applicable ranges of chemical grouting protection wall in the excavation of deep foundation pits. Some technological principles and design considerations of the construction of chemical grouting protection wall are presented. Different types of protection wall are also introduced.

Jan 1, 1991

By M. A. El-Sohby

The paper describes some problems encountered with the foundation of a deep drainage caisson constructed on the Nile Bank in Cairo. The use of suction dredging while sinking the caisson led to a piping failure of the sandy soil in the base which was loosened during the process of pumping. A study was carried out to investigate the problem and a procedure was adopted to retain the stability of the caisson.

Jan 1, 2010

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 Kenneth Gavin

Design practice for piles installed in Irish glacial till has developed in an ad-hoc manner, based on the results of un-instrumented load tests. This had led to designers using similar design parameters for both CFA and displacement piles. To address the concerns of industry a series of instrumented pile tests were performed by two Irish Universities. These tests summarized herein, revealed that CFA piles develop higher shaft resistance than piles driven in glacial till. However, they exhibit low base stiffness and the end bearing resistance that can be mobilized at acceptable pile settlement is low. The use of simple non-linear elastic design approaches to predict the load-displacement response is considered. The methods are used to predict the capacity of two large diameter CFA piles installed in glacial till. While the predictions were reasonably accurate at predicting the initial load-displacement of the piles, significant creep settlement developed at higher load levels. The cause of the creep settlement was investigated through the use of plate load tests and the consequences for pile design are discussed.

Jan 1, 2009

By A. K. Bhattacharya

Cylindrical bridge piers are widely used and equations exist that can predict the maximum depth of local scour around such piers. Scour around piers is an undesirable phenomenon, as it requires the foundation to be placed to a greater depth resulting in increased cost, making it worthwhile to investigate scour-reducing measures. A number of scour-reducing measures have been tried out for cylindrical bridge piers including placing a concrete collar around the pier, having a delta-wing projecting upstream in front of the pier, placing riprap around the pier, using a group of piers instead of a single pier, having a slot in the pier aligned in the longitudinal direction. The objective of this study is to investigate the effect of upstream protective piles on reduction of maximum local scour depth around a cylindrical bridge pier. The upstream piles are placed at different radial distances in front of the pier and the scour depths are observed. The proposed equation of Dey (1997) for determining the maximum depth of scour around a cylindrical bridge pier is used. The reduction of local scour around the pier is compared with local scour around an unprotected pier.

Jan 1, 2009

By J. Nakayama

For installation of round steel piles or cast-in-place pile construction through boulder contained ground or rocky formation, usual system does not function properly or impossible to work. This paper introduces an installation system which combines unique mechanism where the drill is installed on the top of a driving round steel pile or a stand pipe which is initially driven into the overburden to the depth of self-standing. When the pile driving or bore hole drilling encounters hard strata or boulder contained ground, hard material shall be crushed by the down-the-hole chiselling operated in adjustable short stroke and high frequency of blows while cuttings are discharged in reverse circulation through central reverse pipe while round steel pile is simultaneously stroked by a hydraulic hammer. The paper shall explain the mechanism of the system and introduces construction examples for bridge foundation and piled jetty.

Jan 1, 1999

By Y. C. Han

The advances in seismic design considering soil-structure interaction or soil-pile-structure interaction are described using a substructure approach. The nonlinearity of soil is considered approximately using a boundary zone model with non-reflective interface, and computer programs are available for practical applications. The validation of model is confirmed with dynamic tests on piles in the field, and the results for a single pile are used to compare with the predictions in this study. The liquefaction for sand soil layer can be accounted for, and a case of liquefaction is discussed. Two practical examples are examined, a vacuum tower structure supported on foundation of steel pile group and a table top structure supported on foundation of concrete pile group. To illustrate the effects of soil-pile-structure interaction on the seismic response of vacuum structure, different base conditions are considered, rigid base, i.e. no deformation of the foundation; linear soil-pile system; and nonlinear soil-pile system. The method introduced can be applied to the design of tall buildings, bridges, industrial structures and offshore platforms with soil-pile-structure interaction under seismic or dynamic loads.

Jan 1, 2010

By Luo Yang

It has been known that after initial pile driving, pile capacity gain over time (set-up) could constitute a significant portion of the total pile capacity. In the past, there has been very little guidance for incorporating pile set-up capacity in design. This may be due to large uncertainties involved in predicting the pile set-up. A comprehensive statistical database is developed to describe the increase of pile axial capacity with time, known as set-up, when piles are driven into sand. Based on the collected pile testing data, pile set-up is significant and continues to develop for a long time after pile installation. The statistical database shows that a lognormal distribution can be used to describe the probabilistic characteristics of the predicted set-up capacity using Skov and Denver?s equation. The main objective of this paper is to incorporate the set-up effect into a reliability-based Load and Resistance Factor Design (LRFD) of driven piles in sand. A First Order Reliability Method (FORM) is used to derive separate resistance factors that would account for different degrees of uncertainties associated with the measured short-term capacity and the predicted set-up capacity from the proposed semi-empirical equations. The incorporation of set-up effects in the LRFD helps improve the prediction of the total capacity of driven piles, resulting in more economical design. A practical design procedure within LRFD framework to incorporate the pile set-up effect is outlined at the end of the paper.

Jan 1, 2006

By Arturo Ressi di Cervia

Construction of the drilled shafts for the Brightman Street Bridge Replacement Project were not only challenging due to working over the water but were also challenged by changed soil conditions, concurrent work being performed by an adjacent contractor on the same project, environmental restrictions and severe winter conditions. A total of 36 x 8 feet diameter drilled shafts with 7.5 feet rock sockets were installed for the East and West bascule piers. This project also included Osterberg Cell load testing on two production drilled shafts at each the East and West bascule piers. The results from the load test program were used to fine tune the design of the drilled shaft rock sockets. From a constructability standpoint the reverse circulation drilling method with a pile top drill rig proved to be an excellent choice for drilling the overburden and rock sockets of the large diameter deep drilled shafts.

Jan 1, 2003