Search Documents

By Peter O. Wilkinson

Ascot Racecourse in the UK is a major international venue for horseracing. The racecourse is being redeveloped to provide entirely new public facilities. The development includes the construction of a new grandstand. A site investigation was earned out comprising mainly cone penetration testing. The site is underlain by the Bagshot Formation, comprising predominately cohesionless deposits of medium dense becoming dense, silty fine to medium sand, containing occasional layers of clay. Shallow foundations would present uncertainty regarding total and differential movement; hence a piled foundation solution was chosen using a continuous flight auger (CFA) piling system. The possibility that piles may found either directly on or within the influence of cohesive material suggested uncertainty regarding toe resistance. In order to measure shaft friction, an instrumented preliminary test pile was undertaken. The results were compared to published correlations of cone and shaft resistance. This approach resulted in a net saving in terms of pile length which resulted in optimum value engineering and hence a cost saving to the client.

Jan 1, 2006

By Jean Balech

This paper presents some results of dynamic loading tests performed on concrete piles driven in soft clay formation. The load transfer mechanism, measured in the dynamic increasing energy test (DIET), under blows of growing energy, is described in terms of mobilized normal forces diagrams and unitary local friction and displacements. It was observed that the lateral skin friction grows up to a maximum, in the soft clay layer and, gradually diminishes to a residual value when the system presents the maximum mobilized resistance. It may be concluded that the rupture load is not equal to the maximum mobilized point resistance plus the maximum mobilized local friction as suggested by most of static bearing capacity formulae.

Jan 1, 2002

By Roy Jennings

The Discovery Expedition of St. Charles, MO chose to build its two-story museum in the flood plain of the Missouri River, near the starting point of the Lewis and Clark Expedition. Should the lower level be inundated at flood stage, plans call for the replica riverboats to be moved by trailer to higher ground. The museum's design required an open span structure with heavily loaded footing or piles. Spread footings could not be used due to the compressible soil profile. The location, in a historical district, precluded dynamically driven piles. Sixty-three uncased Helical Pulldown Micropiles were driven to the bearing stratum to support the museum with minimum disturbance. There were no spoils to dispose of during construction and the piles were completed in eight working days with minimum impact to the environment and neighborhood. The maximum working load required was 84,000 pounds (374kN). Test results are given in the form of installing torque.

Jan 1, 2003

By Thomas J. Weaver

Piles extending through soft soil near the ground surface will have a relatively low lateral stiffness. As a result, lateral serviceability limits may control the number of piles required for foundation support. Improving near surface soil properties may significantly increase lateral pile stiffness and thus reduce the number of piles required for the foundation. A series of analyses have been performed to assess the depth and lateral extent of soil improvement required to significantly increase lateral foundation stiffness. Analyses consisted of Winkler type beam on a spring foundation and three-dimensional, linear elastic finite element analyses. Results from the analyses show that lateral pile foundation stiffness can be doubled when soil properties are improved to a depth and lateral extent of 5 pile diameters. In order to achieve this increase in foundation stiffness, the modified/improved soil modulus of elasticity needed to be approximately 5 times greater than adjacent unimproved soil. This magnitude of soil improvement over such a limited lateral extent suggests that limited soil improvement can result in more economical foundation designs at soft soil sites.

Jan 1, 2006

By Miklós Kovács

A new type of the cast in situ piles is introduced. The installation of the new pile is based on a pushing in/gaining back procedure. A temporarily closed tip element with square shaped cross-section being attached to an upper circular shaft tube is vibrated into the soil. The steel armature is embedded. Concrete is poured into the tube and, the whole structure is gained back while the tip is in opened position. The width of the tip is less than or equal to 40 cm. The maximum length of the pile is about of 14 m. Great bearing capacity is resulted from the double soil compaction effect. No spoil is generated and, the pile construction can be controlled. The paper presents the results of four loading test at three sites with some soil data.

Jan 1, 2002

By Padmavathi V. Sagi

In this paper, effect of cyclic loading on the behavior of a long, flexible, unrestrained vertical pile loaded laterally in soft clay is examined. For cyclic loading, the analysis is carried out using a new method for the construction of p-y curves and for static loading conditions, p-y curves proposed by Dewaikar and Poonam (2005) are used. An iterative analysis is employed with secant modulus approach using a matrix method known as moment area method developed by Sawant et al. (1994). For pile top deflection of 20% of pile diameter, the load values are computed for both static and cyclic conditions. The comparison of results with the field test results reported by Matlock (1970) shows a good agreement. A parametric study is further carried out to examine the effect of load eccentricity, pile embedment length, diameter and the number of cycles on the pile response. The results of this study are discussed in the paper.

Jan 1, 2006

By Kenneth A. Pidgeon

This paper presents a case history on mitigating vibration problems associated with the installation of steel sheetpiles. The project in-cludes installation of steel sheetpiles for a utility trench within 40 feet (12.2 meters) of a very sensitive manufacturing facility. Numerous production line quality control instruments and manufacturing processes within the manufacturing facility are extremely sensitive to vibrations. To minimize the impact to the owner, we specified that the contractor perform a vibration study using different types of pile hammers. The results and conclusions of the vibration study are presented in this paper.

Jan 1, 1995

By C. L. Liao

The chief experiences for constructing deep tubular columns foundation under deep water are as follows: 1. P.C. tubular columns were sunk inside the caisson. 2. P.O. tubular columns of 3.6 M. diameter were sunk thru thick soil layer to a depth of 47 M. by vibrators. 3. The double wall steel cofferdam was sunk thru soil layer to a depth 31.3 M.. 4. Bore the bedrock with rotary drill succesfully. According to the successful experiences mentioned above, the deep tubular columns foundation may be constructed beyond 100 meters.

Jan 1, 2010

This Workshop was held at the Doubletree Inn, Seattle, Washington from September 26 to 28, 1997. Run under the auspices of the Deep Foundations Institute (DFI), it was co-funded by the newly formed Japanese Association of Micropiles (JAMP), and the Federal Highway Administration (FHWA). The Workshop was jointly organized and facilitated by Fujita Research Corporation and ECO Geosystems, Inc., with close support by Donald B. Murphy Contractors, Inc. DFI kindly consented to publish these Proceedings. As is clear from the list of attendees, 42 specially invited engineers from all aspects of micropile technology were present, representing Japanese, European and American practice. This proved to be a most friendly and interactive group of people, who freely exchanged ideas, views and close comradeship, not only during the technical sessions, but (and especially!) during the numerous social events. Perhaps the best illustration of this came in Day 2 when the attendees were divided into five competing teams, each comprising representatives from the different geographic groupings. These teams had to quickly devise solutions to two technical problems (using standard data previously provided. A team of "referees" (who also acted as "coaches") later determined the most apposite response, based on constructability design concept, cost, schedule and so on. Not only were the winning team very liberal in distributing the prize (vintage California champagne) among themselves, but the whole Workshop soon benefited from their generous division of the spoils of victory.

Jan 1, 1997

By Jean-Louis Briaud

The following is a summary of a very recent report prepared at Texas A&M University for the National Cooperative Highway Research Program and entitled "Downdrag on Bitumen Coated Piles". Anytime the soil settles more than the pile, downdrag or negative skin friction will develop. The load in the pile increases with depth up to a certain point and then decreases down to the pile point. This phenomenon has been quoted as being the number one culprit for deep foundation failures. In Chapter 1, an introduction to downdrag is given. The most common criterion for downdrag is to consider it in design as soon as the settlement of the soil surface after pile driving exceeds 0.5 in. Coating piles with bitumen is an effective way of reducing downdrag forces and therefore allows to use smaller piles for the same load. This results in cost savings. Coating piles with bitumen increase the cost of piles by about 33% and therefore the decision to use bitumen is generally based on economic considerations.

Jan 1, 1989

Jan 1, 1989

By J. Matos e Silva

The paper refers five examples of executed diaphragm walls with one to five levels of anchorages. For each example a comparison is made between the results of the design using the traditional criteria and the Eurocode 7 recommendations. A comparison is also made with the behaviour of the diaphragm walls during the construction phase. From the referred examples the author presents his conclusions.

Jan 1, 2002

By Evelio N. Horta

The influence of soil improvement replacement area in foundation settlements is discussed for soil improvement methods used in Southeast Florida. A 3D Finite element analysis is used for two typical conditions in the area: foundations bearing on loose sands and foundations bearing on a crust of limestone underlaid by very loose sands. Particular attention is given to Jet Grouting as a soil improvement method. The potential impact of the stiffer jet grout columns on the structural foundation design and quality control issues are also discussed. It is shown that in loose sand conditions 15 to 20% area replacement produces substantial reduction in total settlements. Reduction in total settlements for mixed profile is less significant but the use of the method in those cases is directed to reduce punch through potential.

Jan 1, 2007

By Masanoub R. Fujioka

A brief discussion of the methodologies involved in dewatering practices, particularly as used in Hawaii in coralline formations. A description of early dewatering practices includes a number of case histories; later dewatering practices also are detailed with case histories. There were disasters and some successes. Grouting generally was not successful. Deep wells are technically feasible and generally the economical solution to deep basement construction.

Jan 1, 1986

By Kent C. Werle

This brief discusses the installation and application of sleeved piles of two different types for two different projects, the W, Seattle to Harbor Island Swing Bridge Project and the Seattle Access Project. A description of these relatively novel piling systems is given, as well as some notes on their installation and application. As implied by the term "sleeved" these are piles which consist of two piles, an inner pile combined with an outer concentric sleeve pile. Background, Swing Bridge The Swing Bridge project is virtually unique in the world in that it is a "lift and turn" swing bridge. It is also a concrete, cast -in-place segmental bridge which is designed to be moveable.

Jan 1, 1990

Jan 1, 1998

By Wen Songlin

This paper presents an experimental program to investigate the behavior of a pile with wings under horizontal loads in sand at laboratory. The work focused on evaluating the lateral resistance behavior and the geometric effect of wing board on the horizontal resistance. Based on the measured data and observed phenomenon, the following behaviors have been observed: 1) A pile with wings is not only a powerful means to improve the horizontal bearing capacity of a pile foundation but also economy and feasibility; 2) The horizontal bearing capacity of a pile with wings increases with increasing of it?s wing board?s area; 3) The pile lateral capacity is also influenced by the wing board?s geometric shape. Under a certain soil and pile condition, there is a critical embedment depth of the wing board, which will yield the maximum horizontal bearing capacity. It was further observed that when the displacement of the pile head increases, part of the horizontal bearing capacity of the pile is developed by the so-called shaft?s anti-pulling capacity.

Jan 1, 2007

By David E. Albus, Bidjan Ghahreman

A single-family home constructed on the side of a slope in Los Angeles, CA, was subjected to lateral forces due to soil slope creep on the pile foundation supporting the home. Impacts to the property included cracking and separations in the street, retaining walls, exterior concrete flatwork, and decorative concrete features in the rear yard area. The home was supported by concrete piles that penetrated the surficial soil mantle and were embedded in underlying bedrock. However, the home exhibited minor distress that suggested even the home was being affected by soil creep. Selected points on the home were monitored with an optical survey method and manometer over a period of two years to assess if the home was undergoing vertical or lateral movement. Monitoring data indicated the home was in fact moving down slope in a manner consistent with slope creep. As a result, the authors were concerned that continued movement due to slope creep could result in over-stressing of the piles that support the home and ultimately lead to failure of the foundation system. An evaluation was then undertaken to evaluate the behavior of the foundation system due to forces from slope creep. Research was performed during the course of evaluating the conditions to consider various approaches to modeling pile behavior of the piles supporting the home. Some research has been performed to field measure creep displacement of soils and rock in slopes. These previous works have found a diverse behavior of the soil displacement with depth (velocity profile) indicating the process is very complex. An example of various velocity profiles measured in field experiments is depicted in Figure 1. Other research focused on theoretical models of velocity profiles and exhibited similarities to some of the field measured cases.

Jan 1, 2018

By Timothy C. Siegel

A piled raft refers to a shallow foundation that is structurally connected to the piles, while composite ground refers to a soil-pile matrix where the piles are not structurally connected. The design objectives for both a piled raft and composite ground are (excluding special considerations such as expansive soil): (1) to provide a sufficient ultimate resistance and (2) to distribute the load into the soil-pile matrix so that the settlement experienced by the shallow foundation is within tolerable limits. A simplified model is proposed for a shallow foundation on composite ground where the foundation settlement is estimated as the sum of the downward movement of the piles plus the downward movement of the shallow foundation relative to the pile head. The proposed simplified model is applied using conventional geotechnical analyses for two hypothetical examples of shallow foundations undergoing compression settlement.

Jan 1, 2011

By Ke Yang

Drilled shafts are widely used as foundation system for sound walls to resist lateral loads. The design method based on the ultimate lateral capacity, such as Broms method, is often used for sound wall foundation design. Allowable Stress Design (ASD) is currently used for deep foundation design. However, by October 2007, all states Department of Transportations are required to use the Load Resistance Factor Design (LRFD) approach for the design of foundation in highway projects. There is a need to develop a calibrated resistance factor in LRFD lateral design of drilled shafts supporting sound barrier walls. This paper provides resistance factors for design of laterally loaded drilled shafts supporting sound walls using Broms method based on the study using reliability based method and fitting to ASD method. Additionally, the resistance factors for static lateral load tests are recommended. Furthermore, a methodology to update the resistance factors using Bayesian approach by incorporating the on-site full-scale lateral load test results is presented. To illustrate the Bayesian update methodology, two lateral load tests in Colorado were employed to develop the updated resistance factors.

Jan 1, 2007