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By R. Heath Forbes

The route of a new, 4-mile long, electrical transmission line passed through residential neighborhoods and commercial areas of a small town in the South Carolina Coastal Plain. The new line consisted of 54 new poles and a one-mile underground section. Most of the new poles were constructed within 50 ft of existing structures, and in some cases, within 8 ft to 20 ft. A widely-space subsurface exploration consisting of 20 cone penetration test soundings indicated the subsurface conditions along the alignment generally consisted of saturated, loose to medium dense, fine slightly silty to silty sand. The pole foundations consisted of 20 to 30 ft long, prefabricated ?caissons? (essentially an open-end pipe pile with a prefabricated connection system at the top) with diameters of 28 to 56 inches. The steel caissons were installed with vibratory pile hammers. To help prevent damage and defend against possible allegations from nearby property owners, vibration and settlement monitoring was performed during all foundation installation activities. Limited structural condition assessments were also performed before and after foundation installation. For 53 of the 54 foundations, the ground vibrations recorded at distances coincident with the nearest structure locations ranged from 0.05 inches per second to 1.46 inches per second. With consideration of the dominant frequency, the majority of these values were below the commonly used USBM vibration limits. For a foundation installation that was only 8 ft from the nearest structure, a peak particle velocity of 3.06 inches per second was recorded, which exceeded the USBM limits. For all cases, the measured ground surface settlement was negligible (i.e., less than ¾ inch). Several spurious claims alleging vibration-induced damage were made, but the monitoring program provided an adequate defense. One claim involving artwork that fell to the floor during foundation installation at a distance of 8 ft from the house was deemed legitimate.

Jan 1, 2011

By Roy A. Bell

A 200-foot diameter, 72-foot high petroleum storage tank was built in a hillside ravine where a portion of the site contained soft clay fill. Soil-cement piles, 40 inches in diameter and up to 38 feet long, were installed to support the tank shell and ringwall, and a portion of the tank floor by drilling into the stiff to hard underlying soils and weathered bedrock. The goal was to provide a strong enough foundation to resist the seismic tank shell loading and to minimize differential settlement of the tank shell to avoid out-of-round clearance problems between the shell and floating-roof. A cantilevered retaining wall up to 8 feet high was constructed around a portion of the tank perimeter by inserting steel H-beams into soil-cement piles. The cantilever soldier piles for the retaining wall were installed from a temporary earth embankment on the hillside directly over the top of the wall. The temporary embankment was then removed and the tank pad was cut to grade in front of the soldier piles. Some of the soil-cement piles for both the tank foundation and retaining wall could not be advanced to design depth because the drill/mixing tools could not penetrate to the required depth in the hard soils/bedrock. Smaller diameter borings (22 inches in diameter) were drilled through the centers of the short-of-design soil-cement piles to the design depth and then backfilled with concrete.

Jan 1, 1997

By David R. Beadman

This paper discusses how modern techniques of design and construction were used to create the deep stations for the Copenhagen Metro. The deep stations are located in small squares within the city adjacent to many old and sensitive buildings. The architectural design provides a large open atrium to allow natural light to reach the column free platforms to give the citizens of Copenhagen a feeling of safety and security and encourage them to use the Metro. The design and construction contract was undertaken using the relatively new and untried Eurocodes. The resulting stations set new standards of design for underground metros and have pushed forward the frontiers of what is appropriate construction practice to protect the existing and enhance the future environment.

Jan 1, 2000

By Takefumi Takuma, Hiroyuki Nishimura, Shigeru Kambe

"In order to achieve tubular pile driving with low noise and low vibration, the Press-in Piling Method has been adopted on many projects. The method utilizes reaction force derived primarily from previously driven piles to push in the next pile into ground. With attachments, the Press-in piling equipment can deal with hard soil as well as difficult site conditions. At West Toronto Diamond Rail Grade Separation Project in Toronto, Canada, the Press-in piling equipment drove more than 500 of 914 mm (36 inches) diameter tube piles in length of 12 to 25 meters (39 to 82 feet) to construct earth-retaining walls for railway grade separation. Myoshoji River Restoration Project in Tokyo, Japan drove some 600 of 1,000mm (39.4 inches) diameter tube pipe sections in length of 11 to 22 meters (36 to 72 feet) by the rotary Press-in piling equipment to increase the flood drainage capacity of an existing river in highly populated area of the city. Both projects exemplify the advantages of the method in urban settings.1. BACKGROUNDThe Press-in Piling Method was invented some forty years ago in Japan, where a very large number of construction projects were causing widespread construction pollution, especially by pile driving work in densely populated areas. The method has been providing solutions for piling projects which could not have been built otherwise due to the noise and vibration impact to the surrounding communities. The method can be used with various types of piles including sheet piles, tubular piles, concrete sheet piles and so on. With high pressure water jet and continuous flight auger attachments, the Press-in piling equipment can deal with dense sand, stiff clay, gravels, boulders and even soft rock without employing a different set of equipment."

Jan 1, 2015

By Mai Yuanjian

The stabilization effect in large excavation slope with vacuum wellpoints system during construction of a dry dock located in Guangzhou is introduced in this paper. In-situ observations indicate that the effect of wellpoints for decreasing seepage in slope is remarkable even though the muddy sitty clay in it has poor permeability and the slope can remain its stability well. Meanwhile, a non-linear partial defferential equation has been set up to the whole unsteady seepage process as water level in the foundation pit excavated under water goes down to the bottom and so does the seepage in slope due to dewater by vacuum wellpoints system at the same time. And the finite-defference method has been used to solve the equation mentioned above, which differes from conventional wqy where the equation will be linearized firstly. Since the water heads in slope with wellpoints dewatering are more variable, it is necessary to keep non-linear. The calculation results are in good accordance with observation. Vacuum wellpoinnts for slope stabilization in this work is successful.

Jan 1, 1991

By Stefan Larsson, Jan Ekström, Jennie Kock-Larsen, Håkan Garin

"This paper describes the testing procedure (or protocols) for quality control of dry deep mixing columns in a major ground improvement project carried out in Sweden. Quality control was mainly based on column penetration tests performed at different stages in the project and on two occasions after installation. In the paper, the results from the tests are compared with tests on the unimproved clay. As expected, the results show that the correlation between undrained shear strength in the columns and in the unimproved soft soil depends mainly on the in-situ stress. However, the correlation probably depends on when the tests were performed after mixing. When the influence of the in-situ stress was excluded from the analysis, no significant correlation could be identified. This means that the undrained shear strength in the columns and in the unimproved soft can be considered to be uncorrelated when the strengths and the corresponding variability are evaluated with depth from groups of tests.INTRODUCTIONQuality control and quality assessment of deep mixing (QC/QA) constitute a key component in verification of the limit state design. Due to the complex mixing process and varying geological conditions, it is normally not possible to sufficiently assess the strength and deformation properties in advance. In Sweden, the most commonly used QC/QA method for verification of the limit state is the column penetration test (Axelsson and Larsson 2003; Bergman et al. 2013). The method works well but is time-consuming and requires many tests since property variability is normally high. The column penetration test can be used to assess the undrained shear strength Cu,col. However, it is not clear how the strength correlates to the undrained shear strength of the unimproved soil Cu,soil. There are common factors such as the in-situ stress state and the natural water content, which makes a positive correlation probable, i.e. as Cu,soil decreases, Cu,col also decreases and vice versa. The unimproved soil has a natural spatial variability, but it is not known if the improved soil follows the same variation. The mixing process has a substantial influence on the strength variability and may supersede the influence of other factors. However, if a sufficiently good correlation exists between Cu,col and Cu,soil, information from the geotechnical ground investigations can be used in the design and planning of QC/QA of deep mixing in a more stringent manner. Information about the correlation is also essential in reliability based design, where a strong positive correlation may have a negative influence on reliability. However, as discussed by Al-Naqshabandy and Larsson (2013), this correlation may be weak or insignificant for a representative failure domain where the mixing process may have a dominant influence on the strength variability. It is thus of interest to assess the correlation."

Jan 1, 2015

By H. Boghosian

This paper presents the design and construction of a deep basement in a steeply sloping site in glacial till in Glasgow city centre. Existing foundations, adjacent structures and services, in tandem with asymmetric loading, presented particular challenges in the planning, execution and design of the project. The construction methods and temporary works, analysis by the Finite Element method and monitoring carried out are all described.

Jan 1, 2006

By P. Kiruthika, A. Murali Krishna

Soil liquefaction is a dangerous phenomenon that involves huge damages during strong earthquake ground motion event. Stone columns (SCs) are widely used as liquefaction mitigation element which is expected to perform the improvements against liquefaction hazard by densifying, increasing the stiffness and rapid dissipation of excess pore water pressure in the surrounding soil. Although in the recent times few studies on the behaviour of stone columns in the seismic zone has evolved, the performance of SCs in the multi-layered soils is not extensively examined. This paper presents the numerical investigations on the performance of SCs installed in the multi-layered soils as a liquefaction mitigation measure against the seismic loading. The acceleration time histories, Excess Porewater Pressure (EPP), vertical displacement and stress ratio evaluated along different depths using PLAXIS 2D. With the installation of stone column there is a considerable reduction in the acceleration amplitude, which in turn reduces the EPP and vertical displacement at different locations and the amplitude of reduction depends on the soil stiffness levels at the depth.

Sep 1, 2022

By Kul Bhushan

This paper presents the results of lateral load tests on 0.61-m to 1.27-m (24 to 50-inch) diameter drilled and cast-in-place piers in San Diego area residual/formational soils. The test piers were installed and tested in the following soils: Decomposed Granitic Rock (Ktd), Stadium Conglomerate (Tst), and Friars Formation (Tf). Lateral loads of up to 845 KN (190 kip) were applied to the piers in residual granitic soils, and loads up to 1780 KN (400 kip) were applied to the piers in Stadium Conglomerate and Friars Formation. The tests were conducted by jacking against adjacent piers and monitoring the lateral load and lateral deflection at the ground line. Test results indicate that ultimate lateral pile capacities of up to 1800 KN (400 kip) can be obtained for 0.61 m (24-inch) drilled piers with penetration of 3 to 6 m (10 to 20 ft) in the residual/formational soils tested. Lateral load analyses using p-y curves for very dense sand significantly overestimate the observed lateral deflections. For lateral load analyses using dense sand p-y curves, p-multipliers that increase the lateral soil stiffness (p-y curves) by 2 to 8 times are required to match the load-deflection behavior measured in the test piles. When applied to the dense sand p-y curves, the p-multipliers provide a more accurate prediction of load-deflection behavior in the residual/formational soils, and can result in shorter required pier penetration and significant savings in foundation cost.

Jan 1, 2002

By J. P. Burland

The paper describes a number of recent case histories in the United Kingdom where field instrumentation and measurements have played a major role in the design and construction of excavations, piles and foundations. It is shown that the design and construction procedures for deep excavations in London Clay are based almost entirely on the results of field measurements. Examples are given of successful application of such measurements. The present understanding of the behaviour of bored piles in stiff clays and their design is based on a number of instrumented pile loading tests. The results of these tests have led to a radically new concept of pile design in which the piles operate at their full shaft capacity under working loads thereby resulting in considerable savings in design and construction. Some examples of the successful application of this concept are given. Finally it is shown that the present knowledge of the stiffness properties of chalk is based entirely on field observations. An example is given of how direct field measurements were used to solve a foundation problem at the base of a coffer-dam in chalk.

Jan 1, 2010

By Monica Prezzi

"Auger cast-in-place (ACIP} piles and drilled displacement piles are being increasingly used as foundation elements for structures, particularly in projects requiring accelerated construction or involving the rehabilitation of foundations of existing, overstressed structures. Auger cast-in-place piles (also referred to as continuous-flight-auger piles) are widely used to construct the foundations of all types of structures. There are many different types of drilled displacement piles, with the installation methods varying according to the equipment used. Depending on the specific rotary piling technology used, responses ranging from those associated with non-displacement to those associated with full-displacement piles are obtained. Conventional pile design methods do not account for how the various construction techniques involved in auger piling change the soil state around the pile during installation and, hence, cannot accurately estimate the pile resistance in a consistent way. Research on this subject, identifying the different variables that must be accounted for in design and linking these variables to installation methods, is lacking. This paper describes the different piling methods available for auger cast-in-place and drilled displacement piles, the equipment used to install them and the quality control processes typically used. It also reviews some of the design methods currently used.IntroductionDeep foundations are extensively used in geotechnical engineering practice. The wide spectrum of piling methods results in a variety of pile types. Each type behaves differently, depending on the installation or construction methods. On one end of the spectrum are non-displacement piles, the classicql examples of which are bored piles or drilled · shafts. These piles are constructed by removing a cylinder of soil from the ground and replacing it with concrete and reinforcement. On the other end are full-displacement piles, such as closed-ended pipe piles or precast reinforced concrete piles, which are typically driven into the ground. Driven piles preload the materials below the toe of the pile and displace the soil surrounding the pile shaft laterally during the installation process. Therefore, displacement piles are, in general, more likely to have a stiffer response than non-displacement piles. This is true particularly in the case of sandy soils where displacement causes densification."

Jan 1, 2005

By Thomas Domanski

Any type of deep excavation whether for Bored Piling, Diaphragm Walls or Contiguous Bored Piling Walls depends on forming a stable borehole with a defined cross-section to receive safely the permanent materials. In modern construction the excavation depth can reach well the range of 100 m and above. The diameters of the Piles reach often sizes of 2.5 m and bigger. Top casings in Bored Piles (Diaphragm Wall none) are rather short and stability below the casing, need to be secured by stabilization slurry. The boreholes need to be formed through a variety of different materials and stand open for an extended period. Without a safe stable borehole, it is impossible to produce quality products and work cost-efficient. The understanding and proper usage of a suitable slurry is a key element essential for the delivery of Foundation Elements with high quality and within a reasonable budget. The setting of mechanical and rheological parameters in specifications is necessary and helpful, but probably insufficient to embrace and control such a key element in the practical implementation of foundation construction. The proper selection, design, implementation and supervision of slurries on site requires both from Contractors and Engineers to understand how different slurries do function. Only with this knowledge the right decisions in slurry operations can be made. This talk is directed to give some help to both, Contractor’s and Engineer’s, in understanding how different type of slurries do work. (Which ones should be preferred in what kind of soils.) The better knowledge will help the Contractor to control cost and enhance production. The Engineer will be able to assist in arriving at the appropriate technical choices and include in the specifications.

Sep 1, 2022

By Alexander J. Verstraeten

The design and construction of foundations for power transmission line towers present some special problems. This paper describes a system of design and construction for these foundations that was developed in Europe and has attained general use there because of its reliability and cost effectiveness. Transmission line foundations distinguish themselves by having to deal not only with compressive and lateral loads, but with uplift loads and, because of the wind (in some regions earthquakes), with dynamic loading. The construction of transmission line foundations distinguishes itself mainly in the great number of inaccesible locations involved, resulting in extensive geotechnical investigation and logistical problems in moving men, materials and equipment.

Jan 1, 1987

By L. F. Miao

Studies were carried out to investigate the ultimate soil pressure acting on pile(s) undergoing lateral soil movement in soft clay. A special apparatus has been designed to apply a uniform rectangular profile of lateral soil movement on the rigid pile(s) with pinned head and tip conditions to obtain the ultimate soil pressure. The piles were 16 mm (5/8 in) in diameter. For the pile group tests, the behavior of different number of piles (2, 3, 4, 6 and 9), pile arrangements and center-to-center spacings (3 and 6 diameters) were investigated. In this paper, the group factors of 11 combinations of number of piles, pile arrangements and pile spacings are presented. The group factors are given for individual piles in a pile group as well as for the entire group. Generally, the group factors of individual piles in a group varied significantly according to pile spacing in both directions, and pile arrangement; the group factor of the whole group reduced with an increasing number of piles, and increased with increasing pile spacing. For a pile group with the same number of piles but different pile arrangement, no significant difference was found in the group factors for the entire group.

Jan 1, 2008

By George J. Tamaro

The design and construction of foundations in the New York City area are usually dictated by the widely varying geologic conditions encountered in the five boroughs, particularly along the spine of Manhattan Island. Rock extends well above sea level at the northern reaches and falls to depths in excess of 250 m at the barrier islands at the southern extremities. These highly variable geologic conditions, significantly affected by glacial activity, dictate different design and construction approaches throughout the five boroughs of New York City. Extensive rock removal is required at the north while long piling is dictated in the south. Similar changes can occur within a project site on Manhattan Island. This paper will describe these conditions in general, will identify the various solutions used to solve these problems and will summarize various foundation types used in the New York City area.

Jan 1, 2000

By James S. Graham

Foundation pile driving hammers used in New York City in the past 100 years have been drop, steam, compressed air, diesel, and hydraulic. In 1992, the first hydraulic hammer in the New York City area was purchased by Norwalk Marine Contractors, Inc. from Junttan in Finland. It was bought because of its variable energy and ease of mobilization, not because of its higher transferred energy. Heller and Johnsen engineers instrumented hydraulic hammers on nine jobs. The measured transferred energy for the nine jobs was found to average approximately 80 percent. There is no clear consensus regarding the reasons for the hydraulic hammer being more efficient in delivering energy to the pile as compared to single-acting steam/air impact hammers. To minimize pile damage during installation, and to minimize footage overruns, an up-to-date version of the wave equation software that includes an efficiency value of 0.95 for hydraulic hammers is now used.

Jan 1, 2000

By Randy R. Huberty

Although originally designed with deep foundations consisting of all driven steel H piles and drilled caissons, a unique application of Augered Cast-in-Place (ACIP) piles as an alternate design resulted in a significant cost savings for the Midfield Terminal Project at the Pittsburgh International Airport. The project was enormous in scope covering an area two miles long by one mile wide, with changes in elevation of over 200 ft. The varying geology combined with the large amounts of fill required resulted in a complex set of geotechnical design parameters that had to be evaluated through both load testing and analyses. A total of almost 400,000 lineal feet of ACIP piles were installed for this project.

Jan 1, 2001

By Kyle Kershaw

Micropiles are routinely used in the United States for foundation support and stabilization of slopes. In recent years, several retaining walls have been constructed using micropiles in an A-frame type configuration to support temporary and permanent excavations at sites with limited access and limited right-of-way. Typical A-frame micropile walls consist of a row of vertical micropiles at the face of the wall and a row of battered micropiles extending into the soil or rock to be retained. The two rows are then tied together with a pile cap such that the front pile acts primarily in bending and the back pile acts primarily in tension. Because of tight right-of-way constraints at a residential site in Aspen, Colorado, it was not possible to construct the wall using conventional shoring systems or micropiles in the typical A-frame configuration. Rather, the wall was designed such that the row of battered piles was installed at the wall face and the row of vertical piles was installed adjacent to the property line behind the wall. As a result of the reverse configuration of the A-frame wall, FLAC, a two-dimensional, finite difference software program, was used to model the soil-structure interaction. The final wall design consisted of both temporary and permanent retaining wall sections with maximum heights of 26 feet. Inclinometers were installed in several piles to monitor the behavior of the retaining walls during and after excavation. This paper presents an overview of the design method, a discussion of construction techniques, and a comparison between the FLAC model and the measured behavior of the wall in the field.

Jan 1, 2007

By Bao K. Le, Khang T. Truong, Masaki Kitazume, Toru Kobayshi, Long P. Le, Tanaka Hitoshi, Makoto Kamimura, Hoang-Hung Tran-Nguyen

"Earth levees constructed using dredged materials taken from a river along an earth levee have annually damaged in the Mekong Delta due to high void spacing in earth levees and floodwater. Sliding and internal erosion due to floodwater or piping are two key factors causing earth levees’ failures. This study proposed to apply Deep Mixing Method (DMM) to reinforce earth levees in the Mekong Delta, Vietnam. The DMM creates a soil cement wall or soilcrete wall having better engineering properties such as higher strength and low hydraulic conductivity than those of the in-situ soils. The DMM can be applied to reinforce earth levees with limit additional materials that provinces in the Mekong Delta are difficult to supply. The study investigates capacity of the DMM to reinforce earth levees in the Mekong Delta, Vietnam against annual floods. Seepage and slope stability analyses under various conditions were performed with various scenarios of earth levee’s body. The analysis results indicate that the DMM can create a wall that cuts off piping across earth levee significantly and can improve stability against deep sliding due to rapid drawdown of the floodwater.INTRODUCTIONThe Mekong Delta produces agriculture products of 50% of the whole country even though the Mekong Delta has an agriculture area of 30% of the country (Wikipedia 2014). Rice is the main product for the domestic demand and export. This is the main reason why the local people want to cultivate rice 3 times per year to increase the total rice product for export. To do that, the local provinces have constructed earth levees surrounding each area of 100-200-hectare against annual floods to protect rice fields, and farmers can grow rice in the whole year. There are thousands of kilometers long earth levees in the Mekong Delta, and the local governments have spent millions of US dollars to repair and to maintain their earth levees yearly (reports of Dong Thap province 2012; 2014).Earth levees in the Mekong Delta have often failed in flood seasons (e.g., from August to December), especially in Dong Thap and An Giang provinces – the two provinces confronting directly the annual floods from the Mekong River when the floods reach the Vietnam land. The main failure of earth levees is piping, and then causing collapse of some section of an earth levee. An earth levee was usually constructed by piling up dredged materials along a river with minimum compaction. Subsequently, floodwater flows through connected void spacing and washes out soil particles in the body of an earth levee slowly to create piping. Annual wet-dry cycles make the top clay layer swelling and shrinking to form cracks that can store rainwater to trigger sliding (whitlow 2001; Ton That Vinh 2003)."

Jan 1, 2015

By Mahdi Soudkhah, Akhter Hossain

Vertical micropiles are generally considered to be low in lateral resistance. Therefore, battered micropiles are often used when additional lateral load carrying capacity is required. However, battering of micropiles can sometimes be restricted due to existing adjacent structures or utilities, especially in highly urbanized areas. For example, presented in this paper are lateral load test data from a 43-story building project in New York City where vertical micropiles were used due to proximity to adjacent structures. Three static lateral load tests were conducted on micropiles consisting of 13.375-in-outside diameter and 25- to 51-ft-long casings, and socketed 10 to 12.6 ft into the bedrock (gneissic schist). The subsurface profile above the bedrock consists of loose to very dense, mostly sandy and silty soils. The design load for the three test piles was 14,000 lb and the maximum load applied during the tests was 200% of the design load. Lateral load- displacement behavior of the free pile heads from the load tests are compared with the results of p-y analyses based on a widely used p-y method for sandy soils and using a lower and an upper bound estimates of soil index properties and strength parameters. Since the existing p-y curves were formulated for larger diameter driven piles at a specific geographic location, major differences are observed between the results of the load tests and the p-y analyses. In general, the lateral displacements estimated based on the p-y analyses using upper bound soil parameters are relatively closer to the results of the field load testing. Modified p-y curves specific to the sandy and silty soils representative of the general subsurface conditions of New York City matched with the lateral load tests are presented in this paper. INTRODUCTION Micropiles generally are limited in lateral load carrying capacities due to their relatively higher slenderness ratios (ratio of depth to diameter) compared to more conventional deep foundation alternatives, such as driven piles and drilled shafts. So, micropiles are not typically considered as deep foundation solutions when significantly high lateral loads are expected on the substructures. Various means to increase the lateral resistance of micropiles include battering and installing an oversized casing in the top portion of the piles (FHWA 2005; and Richard and Rothbauer 2004). However, it is often not possible to install micropiles in a battered position in highly urbanized areas due to existing adjacent structures or utilities. Installation of oversized casing is often restricted by limited space availability and concerns of losing lateral capacities due to closely spaced group of piles. Thus, estimation of lateral resistance of vertical micropiles can become highly important for geotechnical engineering projects in urban areas when a small to moderate amount of lateral resistances are expected from the substructures, often to withstand seismic and wind loads.

Jan 1, 2019