Search Documents

By Robert W. Schaut

The use of micropiles is increasing for new construction and to retrofit distressed foundations in expansive soils. Typical micropiles in expansive soils have a lower section where the micropile grout is embedded in direct contact with the soil, and an upper section that is cased with rigid PVC pipe or other material to reduce the friction between the micropile and the surrounding expansive soil. In the upper cased section, the micropile grout is in direct contact with the inside of the casing. During construction, grout can flow upward into the annular space between the soil and the outside of the casing as the grout is tremied into the micropile. Thus, various interfaces may exist in a typical micropile, including soil-to-grout, grout-to-PVC, and soil-to-PVC. As the surrounding soil heaves, shear stresses are mobilized along the interfaces. The frictional characteristics of the interfaces are design variables that must be evaluated. For this study, an experimental program was conducted to evaluate the shear strength of the three interfaces listed above. Conventional direct shear testing was performed at a commercial testing laboratory. In addition, specialized testing was performed at Colorado State University (CSU). For the CSU testing, an interface testing protocol was designed using a modified triaxial cell to allow evaluation of the interface characteristics between rigid PVC and cylindrical specimens of grout or clay soil. It is shown that the shear strength of the soil-to-PVC and grout-to-PVC interfaces are similar, both of which are significantly lower than the shear strength of the soil-to-grout interface. This indicates that the use of a PVC casing in the upper portion of a micropile has a positive effect in reducing friction and the shear stresses resulting from expansive soil.

Jan 1, 2011

By S. K. V. Avasarala

This paper presents a case history of design, prediction, probe and production pile driving monitoring, loading tests and installation of over 3,300 prestressed concrete piles for a building complex consisting of 12, 5- and 6-story over parking buildings. The project was recently completed in three-phases over a span of 4 years. The subsoil conditions were explored by performing 25, Standard Penetration Test (SPT) borings throughout the site. Various types of driven pile foundations were considered and following an evaluation of high structural loads and site-specific constraints such as variable depth of bearing layer of Florida limestone and quality of clay and limestone layers, a prestressed concrete pile support system was selected as the most economical and effective foundation approach. The building foundations were designed for a pile capacity of 353 kN (40 tons) in compression, 45 kN (5 tons) in lateral capacity for a deflection of 0.64 cm (0.25 in.), and 133 kN (15 tons) in uplift capacity. The axial and lateral allowable pile capacity and lengths were predicted using SPT91 and LPILE computer programs, which are generally used in Florida. The validation of these capacities was derived from 144 probe piles and performance of 12 pile loading tests on selected probe piles. Prior to installation of probe or production piles, a termination criterion was established using 1-dimensional wave equation analyses in addition to the design pile embedment requirement. The predicted pile capacities compared very well with the capacities from the loading tests on probe piles. This information was effectively utilized as part of the overall quality control program to install a total of 4,186 prestressed concrete piles (including 144 probe piles) in different building areas across the project site to depths ranging from 8 to 21 m (25 to 90 ft) below existing ground elevation as part of foundation support system. This engineered, monitored, and tested foundation solution provided an effective and satisfactory basis for completion and approval of the foundation work for this 12, 5- and 6-story over parking building complex. A recent reconnaissance has indicated that all the building foundations are performing satisfactorily.

Jan 1, 1995

By Dean E. Harris

The realignment of U.S. Highway 95 in Sandpoint, Idaho, is being designed on a site underlain by glaciolacustrine soil that includes very thick deposits of soft, sensitive clay to estimated depths of greater than 200 m. The highway realignment will include construction of numerous embankments, mechanically stabilized earth (MSE) retaining walls, and pile-supported bridges. The area of the proposed new highway corridor also includes existing historic and commercial buildings, a railroad, sensitive environmental areas, and economically vital tourism/recreational assets. The evaluation of pile axial capacity included the use of a variety of methods, including total stress, effective stress, and empirical methods using the results of piezocone soundings and conventional borehole and laboratory tests. These methods were used along with the findings from an instrumented static loading test to design the piled foundations for the bridges. A critical factor throughout the design of the pile foundations was controlling settlements to levels that could be tolerated by the bridges. Also, because of the proximity of the pile foundations to the existing structures and the proposed new embankments, the project has required careful consideration of the potential interaction between these elements. The analysis of piles also considered the potential for settlement of embankments, drag loads on the piles, and downdrag.

Jan 1, 2003

By Gray Mullins

This paper presents results from model and full-scale tests to assess the interface bond between a cast-in-place concrete seal slab and steel H-piles in cofferdams. Three different seal slab placement conditions - fresh water, salt water and bentonite slurry - were evaluated and the results compared against controls where no fluid was displaced by the concrete. Normal pile surfaces were investigated. Additionally, the situation of ?soil caked? piles was also tested. In the model tests, eight 15 cm deep, W6 x 15 sections were used for two different embedment depths of 1.5d and 2d, d being the depth of the section. In the full-scale tests, 16 specimens 35 cm deep (W14 x 90 sections) were tested with the embedment varied between 0.5d-2d. The results show that significant bond stresses developed even in the worst placement condition. Recommendations made for revising current values in specifications have already been implemented by the Florida Department of Transportation.

Jan 1, 2013

By Peter White

A bridge reconstruction project involved driving pipe piles for the new foundations. Disturbances within soil layers at depth caused sinkholes to open up within the construction site. After a near fatal accident, the pile driving installations were suspended. The solution involved ground im­provement through cement grouting with sleeve pipes and special grout additives to minimize migration of cement grout.

Jan 1, 1997

By Peter Chou

A total of 117 slope stabilization drilled piers were installed as part of a major hillside revitalization project. The 110-million dollar development, known as Stratford at Kenwood, included an 18-story upscale senior residential tower, a 3-story healthcare building, and 4-story condominium buildings, offering approximately 580,000 square feet of living space with panoramic views of Downtown Cincinnati, Ohio. In an effort to establish a flatter hillside plateau for the new 4-story condominium and to create a cut and fill balanced jobsite environment, an 800-foot long row of drilled piers and a 600-foot long multi-tiered shear key system was used to terrace existing 1.5H to 3H: 1V steep slopes and support the new fill. These slope stabilization features reduced the amount of spoils needed to be wasted off-site and mitigated the risk of slope instability. An ODOT/FHWA research indicated that spacing of stabilization piers and necessity of top-connecting elements are highly dependent on pier diameter, spacing, soil type, depth to potential failure surface, surcharge loads, and pier deflection. Due to pre-existing deep buried swales, various load combinations, and the complex mechanism of soil arching effects between adjacent piers, both analytical and numerical computer modeling was performed to estimate the loading on each pier. New generation multiplexed, 3-Dimensional, Micro-Electro-Mechanical-System based inclinometers were installed between selected piers to confirm the pier design, and monitor the fill placement, as well as long-term slope stability.

Jan 1, 2009

By Jim Bruce

The Transformation AGO project, constructed between 2005 and 2008, featured a foundation trade contract that included design of pile caps and grade beams and construction of 138 permanent micropiles. The new foundation works were constructed within seven different settings ? each featuring a host of attributes challenging to constructability ? inside and outside the existing Art Gallery of Ontario, all while the gallery remained open for business. Transformation AGO resulted in several firsts for micropiles in the Toronto construction market: this was the first micropile trade contract with a multimillion dollar contract value; it featured the first static compressive load test performed beyond 7000 kN on a single micropile; the first static compressive load test beyond 8000 kN on an experimental pile cap supported by two test micropiles; and it was the first publicly funded project to go to tender with micropiles listed as the preferred foundation option. This paper outlines the successful application of micropiles at the landmark Transformation AGO project.

Jan 1, 2011

By N. S. Yet

This paper shall present the design and construction of bored pile and diaphragm wall for the proposed MHA complex in Singapore. The work was carried out by L&M Foundation Specialist Pte Ltd and PWD Consultants Pte Ltd was the consultant for this project. A brief description of the project is first presented to illustrate the scope and scale of the work involved, which includes the construction of bored piles and diaphragm walls and installation of steel stanchions in the bored piles. This is followed by a description of the methodology used to analyse and design the wall and bored piles. As both towers in this project are supported on bored piled foundation and are constructed by top down construction method, the analysis of the wall has taken into consideration the sequence of work phase by phase and this was carried out by means of a commercial finite element program called CRISP. Modelling of the problem will be briefly described and the findings from the numerical analysis will be presented. This is followed by a description of the structural and geotechnical design aspects of bored piles. The paper shall then describe the difficulties encountered for this project and solution used to solve the problem. The subsoil condition will be described with special mention on the encounter of very strong granitic rock at depth above the maximum excavation level of the basement at certain locations, hence necessitating the drilling of rock for a considerable depth for both bored piles and diaphragm wall. At this juncture, the construction method used to drill through the rock will be briefly described. For construction of bored piles, penetration of rock was carried out by chiselling or drilling using reverse circulation rigs. For construction of diaphragm wall, it requires the employment of Bauer hard rock cutter which uses cutting wheels fitted with roller bits and are capable of excavating into granitic rock of compressive strengths more than 100 MPa.

Jan 1, 2000

By Derrick D. Dasenbrock

Three piers of a new river bridge are supported on 1.067 m diameter open-end steel pipe piles. At time of drive, and after pile re-strikes, high-strain dynamic capacity values at plan tip elevations, were as low as 23% of design requirements. Pile lengths were extended 20% to 40% deeper than planned at two piers, driving to rock, impacting both the project cost and schedule. The significant discrepancy between predicted and observed capacity was investigated through a series of coordinated dynamic tests; a full-scale test pile was installed and monitored over 221 days by both dynamic and quasi-static methods. Unusually slow strength gains were observed by dynamic monitoring on all piles installed at the site. CPT soundings were advanced at the test pile and through the pile interior to investigate the soil plug. High-strain dynamic methods were found to have significant limitations in properly assessing the long-term capacity of large-diameter open-end pipe piles during driving and short-term pile re-strikes. As the benefits of large diameter high-capacity open-end pipe piles are numerous, the geotechnical community needs to address appropriate construction monitoring and control of these foundation types to take full advantage of these systems. An improved understanding of the physical effects of pile installation and the impact on soil strength assessment while driving and long term soil strength gain should be developed and incorporated into both design and monitoring procedures to avoid either unsafe or needlessly costly designs.

Jan 1, 2006

By Joram M. Amir, Ernst Niederleithinger, Nikolaus Schneider

"Abstract: Diaphragm walls are used to provide a stable and watertight confinement for the construction of tunnels, underground railway stations, deep basements and other structures requiring deep excavations. Water seepage and soil loss through the joints have occurred on several occasions, causing extensive damage. This may have been due to uncontrolled concrete flow between the joints, unexpected geologic conditions or just poor workmanship.Different ways of quality assurance are applied on construction sites. Most of them rely on recording parameters of the construction equipment and conventional concrete quality control. In the frame of the EUREKA/ZIM project DiWaQ we have looked at several ways to perform non-destructive quality control. Some methods are to be applied after excavation before concreting (phase 1); others after the wall is completed (phase 2).For phase 1 we have used two different principles for checking the shape of the excavation, especially the joint to existing panels. A mechanical device which can be adapted to the excavating equipment was developed; field tested and validated on test and construction sites. It is described in detail in another paper in the same volume. A sonar-based device with a 10 mm resolution has shown good performance in the lab, but is still under development.For phase 2 different temperature sensors have been lowered into access holes to monitor the hydration heat developed during concrete curing. The same tubes can also be used to perform electromagnetic and ultrasonic crosshole measurements across or along joints to detect flaws. Especially the ultrasonic method has shown promising results on validation specimen at the BAM test site at Horstwalde, but limitations as well. Success substantially depended on the joint type, flaw size and distance of the sensors to the joint."

Jan 1, 2014

By Jan Pru?ka

This paper describes the sheet pile design for the Line C extension from Ládví station to the North of Prague. The first part of the paper describes the geological conditions and structural configuration of the project. Typical cross sections, the description of the construction stages, and monitoring are discussed. The second part of the paper focuses on the sheeting design method. It describes the method of dependent pressures, that is, how the pressures acting upon a structure depend on the deformation. The design process and verification methodology are described in detail with comparison of the results with in-situ monitoring.

Jan 1, 2011

By Richard F. Sliwoski

The Virginia State Capitol was designed by Thomas Jefferson and constructed in 1785. The Capitol is of great historic and architectural significance to not only the Commonwealth of Virginia but to the nation. It is the oldest operating Capitol in the U.S. and required a total restoration/renovation as well as an expansion to continue to remain functional. Site conditions dictated that the expansion (a new visitor center) be placed underground on the south side of the Capitol building, requiring a 40-foot deep excavation approximately 5 feet from the Building. Because of its historic significance, every measure had to be taken to ensure the safety and function of the Capitol during construction. The construction techniques that were used to make the deep excavation and protect the historic Capitol included a tied back concrete slurry wall, jet grouting, compensation grouting, and instrumentation monitoring. This paper describes the history of the Capitol building, the techniques that were employed for construction of the deep excavation, results of the latest movement monitoring, and factors contributing to meeting the restrictive movement goals.

Jan 1, 2006

By Aly M. Mohammad

The Delaware River Tramway will link civic and retail developments in Philadelphia, Pennsylvania and Camden, New Jersey. Twin 300-foot towers will anchor the cables at either side of the river. Four high capacity drilled shafts designed by the Geotechnical Department of DMJM+HARRIS support each of the towers. At the Philadelphia tower, each 6-foot diameter shaft extends 130 feet deep and terminates with a 30-foot rock socket. The shafts are situated within the footprint of an existing relieving platform, which complicates the typical construction sequence. Also, the subsurface conditions at the site provide a unique challenge in both the design and construction of the drilled shafts. During the construction of the four-drilled shafts for the Philadelphia tower, a 6000-ton Osterberg load test was performed on the first shaft to verify design assumption and confirm the shaft capacity. The results of the test were utilized to establish load transfer characteristics and develop foundation design parameters suitable for the site conditions. By doing so the Design Engineer was able to reduce the length of the rock sockets on the remaining production shafts by approximately 5 feet per shaft. As a result, the test provided a significant cost saving to the Owner by eliminating 15 feet of rock drilling from the construction costs. This paper presents a description of the unique design and construction methods adopted for the foundations, also on the Osterberg load test including equipment used, number and locations of strain gages, and interpretation of results. The results and findings presented in this paper could benefit both the design and construction industries because it provides a comparison between geotechnical design assumption and actual field measurements; which has always been a challenge particularly for rock formation.

Jan 1, 2002

By Alain Pecker

The choice of a design concept for a bridge foundation is guided by various factors; several of these factors are indeed of technical origin, like the environmental conditions in a broad sense, but others non technical factors may also have a profound impact on the final design concept. The foundations solutions adopted for the Rion Antirion bridge are described and an attempt is made to pinpoint the major factors that have guided the final choices. The Rion Antirion bridge is exemplar in that respect: the foundation concept combines the simplicity of capacity design, the conceptual facility of construction and enhances the foundation safety. The design of these foundations was a very challenging task which required full cooperation and close interaction with all the parties involved: concessionaire, contractor, designers and design checker.

Jan 1, 2005

By F. Z. Suo

Baoahan Iron and Steel Complex is situated at lower beaches of the Yangtze River. The subsoils 50~70 M below the surface is a deposite of Yangtze River delta, consisting mainly of weak silty clay and loam, with low soil bearing capacity. Consequently, to build on such a weak soil a grant iron and steel integrated works weak soil improvement at the Complex, pile foundation is the effective type. It is estimated that at the first stage of Baoshan project 60,000 piles have been driven, of which 60% are steel pipe piles and 40% reinforced concrete piles. To provide reliable basis for pile foundation design, on-site loading tests were carried out for long reinforced concrete piles 27,45 60 M in length ,with strain gauges on the chief reinforcement of pile shaft and strain rod on pile tip. Based on loading tests, the paper discusses and analyses some issues, including determination of load transfer mechanism distribution of frictional resistance. Tests show that as far as long friction piles in soft clay are concerned, regardless of the properties of pile tip's bearing stratum, loads are mainly carried by shaft frictional resistance which it is effective to determine pile capacity in terms of P ~ S relationship.

Jan 1, 2010

By Robert Fernie

Demographics and Infrastructure demands have led to a significant increase in construction of: deep basements for buildings and, trough structures for Highway and Rail/Metro. Concrete embedded walls used for temporary works can be incorporated into permanent works and because of this (and geological conditions) tend to be favoured in UK. This paper considers British practice in the provision of diaphragm (slurry) walls secant (true and pseudo) piled walls contiguous piled walls Plant utilisation, construction techniques, reinforcement placement, connections, propping, water tightness, tolerances, general UK practices and their relation to design practices are discussed. [ ]

Jan 1, 2000

By John R. Wolosick

MACROPILES are defined as ultra-high-capacity micropiles, with working loads in excess of 250 tons. The piles are typically 9-5/8 to 24 inch (244 to 610 mm) outside diameter. They are drilled and grouted in place, with either large diameter steel bars and/or steel pipe reinforcement. The piles are typically tested to twice the working load. Piles with working capacities of up to 500 tons and tested to 1000 tons have been installed. The paper discusses MACROPILE design philosophy, construction techniques, and two case histories where this innovative foundation system has been installed. Macropiles are descended from micropile technology pioneered in the early 1950s by Fernando Lizzi of Italy.

Jan 1, 2006

By Sanket Rawat, Ravi Kant Mittal, Vikash Prasad

"The understanding of the response of pile foundations under various types of loads is a necessary prerequisite to analyze and design them properly. Therefore, this paper highlights and compares the provisions available in Indian Standard IS 2911:2010 to estimate the capacity of laterally loaded pile foundation with the provisions available in different country codes and existing literature. Comparisons are made between the Indian standard method, Broms method and Matlock & Reese method for the analysis of laterally loaded piles due to popularity and prevalence of the later methods in design offices worldwide. This has been achieved using a parametric study on pile embedded in pre-consolidated clay and sand for both fixed head and free head case in terms of displacement and ultimate load capacity. It has been found that there are various limitations to the Indian Standard method associated with various cases such as short pile analysis, complete moment distribution etc. Therefore, suitable recommendations have been made on the basis of the above comparison to improve the accuracy of the design in Indian perspective. The proposed comparison and subsequent area of improvements will present the design engineers all across the globe, a broad sight of design specifications of laterally loaded piles.INTRODUCTIONPiles in groups are very often subjected to both axial and lateral loads. In the 1960’s, designers used to assume that the piles could carry only axial loads and the lateral load is to be carried by batter piles. However, later, a large number of load tests authenticated that vertical piles also can transfer lateral loads through shear, bending, and lateral soil resistance rather than purely acting as axially loaded members. Initial attempts to analyze laterally loaded piles used the finite-difference method, as described by Howe (1955), Matlock and Reese (1960), and Bowles (1968). Matlock and Reese (1956) used the finite difference method to get a series of non-dimensional curves to enable the user to input the appropriate curve with the given lateral load and estimate the ground-line deflection and maximum bending moment in the pile shaft. Later, Matlock and Reese (1960) extended the earlier curves to include selected variations of soil modulus with depth."

Jan 1, 2017

By Jason N. Scott

CFA piling is a ?blind? construction process that relies heavily on the rig instrumentation to produce sound piles. If the data measured and recorded during construction can be made available to engineers and managers within hours after construction then there are many economic and quality control benefits that can be realised. A state of the art CFA instrumentation and data management process has been developed in the UK. The key components of the instrumentation, GSM data service and the central database are described. Many benefits to the business have been realised and, where possible, these are quantified.

Jan 1, 2006

By Lance A. Roberts

Expansive soil formations can be found throughout the United States. When subjected to wetting, these formations have the potential to swell and exert large uplift forces on buildings and foundations. Lightly loaded structures, such as single family residences founded in areas of expansive soils, can be significantly damaged due to uplift movement from swelling actions. Designing an economical deep foundation that can resist uplift forces is critical to prevent damage to these structures. The current solutions to control uplift due to swelling soils, such as over-excavation and replacement of the expansive material or the use of drilled shafts can be costly. Piles made from recycled polymer materials could provide a solution. Due to a lower coefficient of friction along the interface of the soil-pile interface compared to traditional pile materials, solid recycled plastic piles can allow expansive soils to move nearly independently from the pile when wetted. This results in a much smaller magnitude of uplift force being transferred to the structure, which minimizes the risk of significant structural damage from excessive movements. This paper presents the results of research conducted on the use of recycled plastic piles in an expansive shale environment. The preliminary phase of the project involved the installation of six recycled plastic piles at a test site on the South Dakota School of Mines and Technology campus. Two of the piles were subjected to a full-scale compression load test in order to determine ultimate capacity. The remaining four piles were subjected to long-term monitoring of uplift movement during the course of the project. A concrete anchor was also installed at the test site for uplift monitoring. Data gathered during the field and laboratory testing was utilized in a non-linear soil-structure interaction model to predict the displacement behavior and internal stresses within a plastic pile and concrete anchor subjected to uplift forces from the swelling shale. While more research is needed to further understand the application for recycled plastic piles, the results from this research indicate that their use is a viable alternative for support of lightly loaded structures in expansive soil environments.

Jan 1, 2010