Search Documents

By Ignatius P. O. Lam

This paper presents information on design analyses of large diameter piles using conventional p-y curves as recommended by the American Petroleum Institute (API RP2A, 1993). API RP2A adopted the soft clay criterion developed by Matlock (Matlock, 1970) based on 12.75-inch piles. API RP2A also adopted the API sand criteria originally introduced by Reese, Cox, and Koop (Reese et. al., 1974) based on 24-inch piles. Since Matlock and Reese published their original papers, there have been several publications recommending changes to their p-y criteria, especially regarding the need to adjust the Matlock p-y curves for pile diameter effects. The following sections attempt to clarify the issue of diameter effects on p-y curves.

Jan 1, 2013

By Wanchai Teparaksa

Pile deviation generally can happen after installation of driven pile particularly in soft soil layers. In this case study, all 242 diameter 0.8 m spun piles were deviated from 20 to 820 mm. The large deviation was caused by lateral soil movement in the top very soft clay layer of thickness about 23 m. This very soft marine clay is very sensitive and anisotropic having high water contents of over 120% and low undrained shear strength of 5-10 kN/m2. The remedial works were carried out based on theory of load transfer and soil-structure interaction. All deviated piles were rectified and used as the foundation piles with strictly controlled pile load tests. The construction of a nine-storey building was successfully completed founded on the rectified piles and it has been opened for the service for over two years.

Jan 1, 2002

By Frank Rausche

Although Quality Control (QC) during construction is preferable for deep foundations, there are many instances when it is necessary to resort to Quality Assurance (QA) methods if, for various reasons, QC is not possible. Non Destructive Testing (NDT) methods for deep foundations are indirect approaches, i.e. in complex situations they do not provide complete information and need to be augmented by additional testing and/or analyses. While the challenges are varied for the different deep foundation types and the different test methods they are the same in many different countries. Experience of the tester is often mentioned as being most important for a successful quality assurance. In addition, reliable testing equipment for the best possible measurements and complete construction documentation for a meaningful data interpretation are minimum requirements for a successful test outcome. Another problem is the widely varying cost of the QA tests. For that reason the specifying engineer or authority has to be aware of what can reasonably be expected so that technically feasible specifications can be written for optimal cost and minimal construction delays. This paper discusses the most common NDT methods with a view on how these methods are applied world wide. It summarizes features of specifications, recommendations for test procedures and advanced analysis methods which can help to overcome uncertainty in the quality assessment of the foundation. Finally, the authors propose a decision tree for various QA methods, deep foundation types and soil properties.

Jan 1, 2008

By Gerry Houlahan

The east span of the 3.5 km long SF-Oakland Bay Bridge is supported by different types of foundations along its span. Starting from the west, its first 460 m section comprising twin concrete box-girders is supported by sands and rock on Yerba Buena Island. A 620 m long steel suspension span then bridges a 25 m deep channel that is formed in sediments overlying rock. Twin concrete box girder structures, each 2.4 km long, complete the stretch over the remainder of San Francisco Bay to the engineered earth fill landing at its east end. For most of its length, the Skyway bridges water 3 to 10 m deep over soft surficial Young Bay Mud. The foundation types include spread footings with hold-downs, steel and concrete piles that are set in drilled rock sockets up to 3 m in diameter and 2.5 m diameter steel tubular piles driven to penetrations of up to 100 m. The design and construction-related considerations are presented. The different foundation types, influences of the site geology and earthquake demands on the substructures are discussed. The seismic motions of the bridge superstructures and substructures, as well as the depth-varying soil motions, influenced the foundation design. Together with performance-based design criteria, including post-earthquake footing displacement limits, these seismic demands influenced various aspects of the foundation design, including the use of battered and vertical piles.

Jan 1, 2013

By Xuhui

Pile foundations are underground projects which are carried out under complicated site conditions, so it is difficult to summarize their characteristic patterns from the everchanging practical pile foundations. In combination with theories, the paper analyses the effects of sound reinforced concrete piles and various types of defective piles on the propagations of stress waves. Through testing on prototype pile models, by use of the transient dynamic method and comprehensive analysis in both time domain and frequency domain, their reflection characteristics and patterns are acquired. In addition, discussions are carried out in combination with some real projects. Our model tests include comparison of large scale pile models of 20X20cm in cross section, 5. 0m in length respectively in air, standard sand, and natural stratum; prototype model tests of digged piles of 0. 7-1. 2m in diameter, and 18m, 30m in length; prototype model tests of bored piles of 0. 6m, 0. 8m in diameter, 12-20m in length. Test results show that no matter in air or buried in medium, the intrinsic characteristics of sound piles and various types of defective piles are fixed. In their time domain waveforms and spectral diagrams, obvious regularity are shown, which proves that the relations between the pile natures and their dynamic responses are fixed, which provide basis for correct judgement of pile soundness and natures of defective piles.

Jan 1, 1991

By Gary M. Weinstein

Micropiles have seen increasing use for foundation support and slope stabilization applications over the past half century. Most often designed and installed in groups of vertical or battered elements or combinations thereof, continued applied research conducted through partnerships established between academia, government and industry has led to the recent development of practical engineering and design guidelines for such micropile systems. In contrast to a group of directly loaded micropiles, the micropile network relies on a three-dimensional array of reticulated elements to encompass and internally reinforce the soil, resulting in a network or "knot" effect. The potential for enhanced engineering behaviour of reticulated micropile network systems compared to that of a group of micropiles has been continually revealed by numerous researchers in the past. The concept is elementary - the roots of a tree interact with the soil to form a composite foundation capable of performance superior to that of the individual parts. However, given the large number of parameters which must be modelled and studied, experimental assessment and rational analysis of the soil-structure system has been difficult and therefore, in contrast to above, reliable design methods have not yet been forthcoming.

Jan 1, 2003

By Kyle A. Kershaw

The City of Grand Forks, North Dakota obtains drinking water from both the Red River and Red Lake River through a system of raw water intakes, shallow pipelines, and pump stations. However, during flood events, the City often loses access to the system, as evidenced during the record flood event in 1997. As a result, the City decided to construct a new gravity raw water intake system, including a pump station at the base of a 65-foot-deep, 60-foot-diameter caisson, behind a new levee system. Because of high design flood elevations and connectivity of river head to underlying soils, uplift resistance was required for the caisson. A total of 37, 2-foot-diameter, augered cast-in-place (ACIP) piles were chosen to provide uplift resistance. Because of the difficulties associated with installation of piles within the confined space of the constructed caisson and basal stability concerns, installation was completed from the existing ground surface to a depth of 120 feet. Several design and construction issues arose, including squeezing ground during pile installation, placement of long reinforcing bars, and installation of a dual material pile. A dual material pile was required to ensure that the ACIP pile below the base of the caisson was structurally sound and the pile above the base of the caisson could be easily excavated during sinking of the caisson. This paper discusses the solutions to each of these issues, as well as construction sequencing, load testing and integrity testing of the ACIP piles, and the successful completion of the project.

Jan 1, 2003

By J. K. Mitchell

Soil improvement is examined within the context of the characteristics of different soil types, the types of ground improvement techniques that can be used to improve them, and the level of improvements that might be achieved. Several case histories are described to show how the particular soil and foundation characteristics influence the choice and success of different ground improvement techniques. Although the basic methods for soil improvement have been known for many centuries, there have been significant recent advances in the technology for their use. Time effects following the densification of cohesionless soils may lead to significant improvements in strength and stiffness. Unanticipated chemical reactions may follow stabilization using admixtures when soils for which there has been little prior experience are encountered. In some cases foundations that combine features of both ground improvement and deep foundation systems may provide good performance at reasonable cost.

Jan 1, 2010

By W. Morgan NeSmith

A drilled displacement pile program was utilized for the expansion of an existing power plant in Cohasset MN adjacent to the Mississippi River. The drilled displacement (DD) pile is an innovative foundation type that provides exceptional value in some geologies. In the U.S., DD piles have typically been used in coarse-grained soils due to the large friction capacities that can be generated by the piles in these conditions. This project was the first large scale experience for the project team where it was anticipated that significant portions of the DD pile capacity would be developed in primarily fine-grained soils. The project site consisted primarily of variable amounts of fill overlying predominantly low plasticity alluvial silts. In some cases, alluvial silty sand layers were encountered within the expected pile installation depths. Alluvial sands were typically encountered below the silts, in some cases within the expected pile installation depths. The project team developed a probe and pile load test program to address the variable subsurface conditions across the site. The program included monitoring various parameters (including applied torque and tool penetration rate) during the drilling portion of the pile installation using recently developed data acquisition techniques. This data was used to estimate the rig energy, or Installation Effort (IE), required for pile installation. IE profiles from the test and indicator piles were compared with subsurface data available from a number of previous site characterizations. Additionally, Cumulative IE values were compared to an in-house database of IE vs. DD Pile Capacity. Final production pile toe levels were based primarily on IE values selected from this comparison. The IE data collected during production was also used to address large variations in pile-cutoff elevation (relative to a fairly uniform ground surface elevation).

Jan 1, 2008

By Charles M. Wilk

"Mass stabilization (MS) is a ground improvement technique that can prepare areas of low bearing strength soil for subsequent infrastructure development. The technique involves mixing binding agents such as portland cement, fly ash, slag, or lime into the subject soil while the soil remains in-place (insitu). The binders “cement” the soil grains together to form a cement modified soil or a soil cement. The MS-treated area now has improved bearing capacity to support infrastructure or to prevent movement of the material such as landslides.The same insitu soil mixing technique can be used to address contaminated areas. Binders or reagents are mixed into soil. The treatment protects human health and the environment by immobilizing hazardous constituents within the treated material. When used for the purpose of environmental remediation the technology is called Insitu Solidification/Stabilization (ISS).Both Mass Stabilization and ISS treatments require laboratory studies to develop a mix design of soil and binder(s) that produce the desired physical and/or chemical properties. The mix design is then transferred into the field. Successful MS and ISS treatments rely on reproduction at full-scale of the mix design and the thorough mixing attained at laboratory scale. Fifty to 70% of the cost of a MS or ISS project is in the cost of the binding agent that is to be mixed into the subject soil. Under-dosing, overdosing, non-thorough mixing, and mixing in the wrong areas all create cost over-runs.This paper will discuss recent innovations in mass stabilization systems that improve the cost effectiveness of the treatment technology. Specialized equipment can impart greater mixing shear thus improving the thoroughness of mixing. Dry powder pressure feeders can conserve the “drying capacity” of binder resulting in higher strengths at lower binder dosages. Global Positioning System (GPS)-based systems can guide the mixing operator for complete mixing coverage. An integrated tracking and feeding system can record that proper dosing and mixing was accomplished and generate construction QA/QC reports for the client.INTRODUCTIONNew or expanding infrastructure projects may encounter areas of low bearing capacity soil or areas where marginal materials such as waste, dredged material, or sediment have been placed. Mass stabilization is a geotechnical method that can be used to improve the bearing capacity or stiffness of soil. Mass stabilization involves mixing binding agents into soil subject to treatment while the soil remains in-place or insitu.Mass stabilization technique can also address contaminated soil therefore, the same technique can be used to attain both civil and environmental engineering goals. In this environmental application the technology is known as insitu solidification/stabilization (ISS). ISS protects human health and the environment by immobilizing hazardous constituents within the treated material."

Jan 1, 2015

By William F. Loftus

When high capacity diameter pipe piles are driven open-ended into the underlying bedrock, the material gathered inside the pipe often must be excavated to allow concrete to be placed within, in a clean environment. This paper discusses a method of dealing with this ?to be excavated material - the contaminated soil of the Harlem River in New York City, USA.?

Jan 1, 1996

By P. M. Deshpande

An interactive short column system is evolved as alternative to deep foundation system in deep layers of marine clay, the interaction of encased stone column and marine clay carry load without causing conventional settlement. This paper presents concept of the system and its field application as foundation of culverts on marine clay layer of 15 to 17 M underlain by residual soil layer of 5 to 6 M, where conventional pile of 23 to 25 M would have been required.

Jan 1, 1996

By X. Y. Hou

The design practice of several circular underground projects with large diameter is summarized. By taking the advantages of load-bearing of circular structure, a rational annular tensile bar support system and a new design method are proposed. Calculation for a car park shows that remarkable results are brought in by this design technique.

Jan 1, 2010

By Madhira R. Madhav

In an alluvial deposit consisting of layers of sandy silt with clay and kankar nodules, driven cast in situ piles are provided. The piles end on a stiff bearing stratum To verify the available design capacities, compression, pull-out and lateral load tests are conducted in situ. The elastic continuum approach is used to estimate the equivalent modulus of deformation of the deposit. A comparison is made of the values from the three types of tests.

Jan 1, 1996

By M. Nomura

This paper describes the results and field measurements of two long-term observation tests and two short-term loading tests to confirm the effectiveness of NF piles in reducing negative skin friction. All the test piles were equipped with strain gauges, allowing measurement of the compressive axial forces in the piles. These test results prove that NF piles are effective in reducing the negative skin friction to an insignificant value. Some examples of the design procedures used in Hong Kong and Japan are also presented.

Jan 1, 2010

By C. W. Sheng

In this paper conventional construction procedure is briefly described for the installation of stone columns in soft ground in China. A viewpoint concerning the mechanism of ground improvement by use of stone columns is presented for discussion. Based on the information obtained from field measurement and observation three important problems relating to the construction and design of stone columns are discussed. Finally, a case history is given to show that short stone columns floating within the weak soil layers may in some instance be used to improve the weak strata of great thickness.

Jan 1, 2010

By Yong Jingrong

Based on the results of several test socketed piles in Sichuan, the mechanism of the deformation for a loaded socketed piles is investigated, and the concept of the socketed effect is proposed. The bearing capacity and settlement of socketed pile are controlled directly by socketed effect, that is an important mark different from the other types of cast-in-situ piles. According to the analysis of this effect and factors interferring it, their roles are discussed with the results of test piles. In order to increase the bearing capacity of piles, the ways and methods enhancing socketed effect are recommended.

Jan 1, 1991

By Subhash B. Bhide

Deep foundations are affected by the presence of sulphates, chlorides, organic contents and water currents present in the soil. The sulphates in soil and ground water interfere first with setting of concrete. In long term, growing of sulphate crystals in concrete, crevices can spall the concrete. The chlorides mainly affect the steel. The organic content does not allow the concrete to set. It also reduces the compressive strength of concrete. The frequency and methods of sampling and testing for above corrosive elements are discussed. Presently available methods to avoid attack due to these corrosive elements are discussed. The stipulations by various codes are summarised. A method to assess the short term impact is elaborated with results of field studies. A tool developed to study the presence and effects of underground water currents on concrete is also discussed.

Jan 1, 1996

By K. Oshima

In Japan, earthquakes are experienced frequently. Many buildings and structures in Japan are supported on pile foundations. For these pile foundations, the joint section between the piles and footing (hereinafter referred to as "Pile Head Joint"), where the load of the superstructure is transmitted to the ground through the piles, is important in both the design and construction of works particularly under seismic conditions. This paper discusses the state in which the force is transmitted to the Pile Head Joint, and introduces the basic construction of the Pile Head Joint, based on experimental investigation. Steel pipe piles

Jan 1, 2010

By Jorj O. Osterberg

This paper is for presentation at the 14th Annual Members Conference of the Deep Foundations Institute held at the Hyatt Regency Hotel, Baltimore Maryland on October 10, 1989. This is an introductory presentation of a one hour symposium on the applications of a new testing device. This paper discusses how the device works and its uses. Papers following this describe: - How the cell is constructed and calibrated - Two projects on which the device was used on long driven piles to determine the frictional capacity - A bridge project on which the device was used on an instrumented test drilled shaft and a working drilled shaft

Jan 1, 1989