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By Pierre Gouvin

"This paper discusses real time monitoring of utility vaults during the reconstruction of the Elliot Bay Seawall in Seattle. The project, undertaken because deterioration of the old wall posed increasing risks to property and lives, impacts businesses, ferry terminals, a rail line, and electrical utilities that distribute power to much of the downtown area. The project, which has been fast tracked to minimize risk and commercial impacts, involves multiple contractors with heavy machinery working in an area one mile long and only a few hundred feet wide. This presented challenges to monitoring of the utilities, as will be discussed in the paper.INTRODUCTIONThe Elliot Bay Seawall (EBSW) was built in over a period of 18 years, starting in 1916. It consisted of a vertical concrete wall placed on a timber pilings and timber relieving platform. The seawall also retained fill that served as the foundation for a road known as the Alaskan Way. The seawall has performed well over the years, but now cracks in the concrete have allowed loss of fill, and the timber piles and support structures have been weakened by marine boring insects.The project to replace the seawall was undertaken because deterioration of the old wall posed increasing risks to property and lives. Because the project impacts businesses, tourism, ferry terminals, and a rail line, it was given a compressed timeline - 36 months from start to finish. In addition, construction activities have been staged carefully to minimize disruption of Salmon and other wildlife living in Puget Sound. In fact, will incorporate several habitat improvements to promote sea life, such as a nature-imitating textures in the surface of the wall and a glass deck structure that allows sunlight to reach the water. (Fig. 1) shows a schematic of the planned new wall.The sheet piling, concrete piles, jet grouting, drilled shafts, ground freezing, and demolition activities are all taking place in the narrow corridor that holds the subsurface ducts and vaults protecting Seattle’s electrical power distribution. If the network of duct bank and vaults were to experience differential settlement during work here, then most of downtown Seattle would be in the dark. Thus it was important to provide real-time displacement monitoring of these utility structures."

Jan 1, 2017

By Gilbert R. Tallard

"Pouring deep foundations by the tremie pipe method is nowadays such a common process that it has becomes an unspecified practice. Means and methods are almost entirely at the contactor’s discretion. A variety of practices are permitted and seldom associated with the discovery of abnormalities and areas of random defects in concrete. This writer wishes to call the attention of stakeholders to the initiation details of the tremie pour operation.KEYWORDSINTRODUCTIONThe advent of slurry as a means of shoring an excavation of relatively small cross section but of possibly great depth has become part of state of the art in foundations construction, with the substitution of said slurry by concrete to provide the structural end product element through the use of tremie pipes. In appearance, there is nothing more simple than pouring concrete into a tremie pipe through a hopper after the basic work has been done i.e. the excavation or drilling, the cleaning of the slurry, the placement of the reinforcing cage, then the tremie concrete pour is almost a reward for a successful achievement. Force of habit has removed the awareness on the process fundamentals for initiating the pour; a variety of practices used call for a review and a reassessment as a means of reducing construction defects that may result from flawed practices, and and especially we are pouring deeper holes. This writer intends to address this issue focusing both on the drilled shaft and the diaphragm wall industries.TREMIE PIPES AND HOPPERSA tremie pipe diameter needs to be sufficiently large to allow the rapid descent of concrete with a minimum of friction loss and avoiding possible bridging in relation to aggregate size. Impervious joints between pipe sections are essential to prevent slurry “raining” over the concrete which can cause concrete segregation pockets and possibly plug the pipe with damaging consequences. That tremie pipes be long enough to reach the bottom may be self-evident but poorly written specifications can be erratic on that subject and seldom specific in terms of inches. A standard pipe of 10 inches is well accepted throughout the foundations industry; double O rings and spline joints are common and function well if properly maintained. However the practice to cover the joint with the ineffable duct tape indicates that all is not always well with this detail. Also, spline cables may shear in case of very long tremie pipes causing the separation of the tremie pipe requiring a restart in midstream with another probable source of inter mixing of concrete and slurry with subsequent defects."

Jan 1, 2017

By G. W. Plant

This paper describes the design philosophy and construction details of piles between 25m and 32m deep to support 160m high and 110m base diameter cooling rowers for a major power station. It is sited on deep expansive soil where a vast plantation of Eucalypts had been felled. The depressed water table is expected to rise, leading to swell of the soil and uplift forces on the piles. These forces, combined with the complex loading from the cooling towers, led to design tensile loads up to 20MN (2 000 tons) per pile. When competent stable material was present hand excavated underreams 3m in diameter were constructed for the piles sup-porting the shells. However, in some areas it was not possible to form an effective underream and an innovative solution was sought. This comprised unstressed dowels in the underlying sandstone which were formed by percussion drilling through void formers cast into the piles.

Jan 1, 2010

By Dan Brown

Deep foundation contracting for transportation projects in the United States has typically followed the design-bid-build model in which contractors bid on a specific work product according to relatively inflexible prescriptive specifications. With continuous flight auger piling and the many types of proprietary drilled displacement auger piling, there appear to be advantages to contracting this work according to a different model. This paper provides a discussion of the use of a performance specification for this work in which the contractor has greater freedom to choose the most appropriate foundation system and also greater responsibility for the performance of the completed foundation. With public agencies subject to open bidding, this type of contractual arrangement presents opportunities to encourage innovation. There are also challenges for implementation in public works projects, notably the selection of qualified contractors and the verification of performance requirements on production foundations.

Jan 1, 2006

By Shoichi Tsukuni, Akihiko Uchida, Kazuo Konishi

"In order to investigate the effect of grid-form deep mixing walls as a countermeasure for liquefaction damage to roads and private houses in Urayasu, Japan, three dynamic centrifuge model tests were conducted. Urayasu is located in the Tokyo Bay area, and private houses in the city incurred severe damage due to liquefaction during the 2011 Tohoku earthquake. In grid-form deep mixing walls design, the distance between grid-form walls is critical to prevent liquefaction. This study clarifies the relationship between the settlement of private houses and the distance between grid-form walls under the conditions that exist in Urayasu.INTRODUCTIONMany private houses in Urayasu, Japan suffered severe damages due to liquefaction during the 2011 Tohoku earthquake (Photograph 1). Fig. 1 shows the location of Urayasu and the maximum acceleration of the observed seismic waves in the Tokyo Bay area. At Urayasu, the duration of the seismic waves (hereafter called the Urayasu Wave) was about 2 min. The maximum acceleration was 1.57 m/s2 (Fig. 2), which is relatively small. The damages occurred in the land reclamation areas that consist of loose sand with an SPT-N value less than 10.To prevent liquefaction in future, it is necessary to adopt suitable countermeasures in the areas where many private houses suffered severe damages. Grid-form deep mixing walls are one such countermeasure. Fig. 3 and Photograph 2 show grid-form deep mixing walls. Walls are constructed using the deep cement mixing method. Fig. 4 shows a plane view of planned grid-form deep mixing walls for roads and existing private houses in Urayasu."

Jan 1, 2015

By Daniel Ruffing, Charlie Krug

In recent years, the chain-style trencher has been proven a valuable tool for installing vertical walls on challenging sites where conventional methods may be less desirable. Like many tools, trenchers are most effective when used with the right application. Trenchers are commonly used for applications that could also be completed with conventional slurry trenching; low-permeability cutoff walls, collection trenches and permeable reactive barriers (PRBs). Drawing from a wealth of experience with conventional slurry trenching and the trencher, this paper compares and contrasts the technical considerations, treatability, installation, performance, and lessons learned for recent projects.

By Bill Shea, Gordon King

"For a drainage channel built in San Juan, Puerto Rico, a value engineering (VE) proposal incorporating a secant pile top-down approach saved time and facilitated construction work on the larger flood control project. The channel, at the Bechara Industrial Area, Puerto Nuevo Port Facility and the Puerto Rico Maritime Shipping Authority Dock, was needed to allow drainage of the Rio Puerto Nuevo into San Juan Bay. The port area, one of the busiest in the Caribbean, has over 6,000 ft (1,800 m) of berthing wharves for ocean-going container ships along with over 500,000 sq ft (46,000 m²) of container loading and unloading areas, and is critical to the local economy.Planners wanted to minimize the impact of construction to the port and dock users, and developed a construction methodology and work sequencing that would prevent a complete barrier to port traffic. This plan involved non-contiguous and limited work area that “leapfrogged” along the alignment so as to prevent long barriers to lateral traffic movement across the culvert alignment.After reviewing the project plans and schedule, Morris-Shea Bridge Company (MSB) proposed an alternate design and construction approach that provided significant cost and schedule benefits, and also provided better access for the port and dock users. The alternate VE proposal involved top-down construction methodology and redesigned drainage culvert geometry with two parallel 2,000 linear ft (lf) (600 m) secant walls installed on each side of the culvert. These walls facilitated excavation and formed part of the culvert permanent walls. The result was a significantly reduced required construction right of way that allowed construction work in contiguous areas largely without impact on ongoing port activity. MSB conceived the design concept, and engineered design and construction of the VE alternate secant pile culvert.The project initially consisted of an open channel in the industrial area picking up water from the existing Rio Puerto Nuevo, transitioning to an enclosed culvert through the port and dock areas, and outfall through the existing dock. The base bid construction included three main areas of work:"

Jan 1, 2012

By Alan Alhadeff

Why is mediation being hailed as the wave of the future? The high cost of putting on a trial, over-crowded court calendars and long trial delays have resulted in what prominent attorneys and leading jurists are calling a litigation crisis. In no segment of the legal world are these pressures greater felt than in the trial of the serious construction case. Furthermore, the siege mentality of both the plaintiff and defense bar often leads to a reluctance by either side to make the first reasonable offer for fear of showing weakness. Attorneys operating in the serious construction case arena express concerns that there exist insufficient opportunities for the parties to meet, tell their stories, and negotiate settlement prior to the eve of trial. Mediation, by opening lines of effective communication and encouraging meaningful settlement negotiation, has proven to be a very effective antidote to the litigation crisis.

Jan 1, 1990

By E. W. Raabe

The paper discusses the increasing role of specialist grouting techniques to form water seals or cut-offs for deep basement construction. Raabe and Toth discuss the various grouting methods available for sealing applications and then concentrate on the use of Soilcrete Jet Grouting, a system particularly well suited to ground water control. The Soilcrete processes, suitable soil types and quality control methods are fully described, particularly with regard to the formation of cut-off walls and sealing slabs to prevent the progress of ground water or leachates. The authors have included case histories detailing their experience on designing and installing Soilcrete seals for various projects in West Germany. These include an underground rail project in Dortmund and a discharge structure for the Alz Canal at Burghausen.

Jan 1, 1989

By K. E. Darnell

Drilled pier foundations have long been a favored foundation type for heavily loaded structures. Drilled piers derive their load-bearing capacity from end-bearing, and/or sidewall friction. This type of foundation is used in many geologic settings, including those areas underlain by hard carbonate rock, such as limestones and dolomites. When properly designed and constructed, drilled piers provide high load-carrying capacity in both compression and uplift. However, carbonate rock is often subject to intense differential weathering resulting in the formation of an irregular bedrock surface, sinkholes and caves; consequently, the investigation for, and the design of, drilled pier foundations is often complex. Further, the construction may be difficult and costly. This paper discusses geotechnical investigative procedures which can be employed to develop foundation design criteria and reduce the frequency of changed conditions. Finally, state-of-the-art construction practices and quality control techniques are discussed.

Jan 1, 2010

By Gokhan Inci

Stability problems with dam spillways on existing landslides and appropriate mitigation measures to remedy them are ongoing concerns for geotechnical engineers. The first successful application of drilled piers as stabilizing structures under the spillway was at the Trinity Dam in Sicily, Italy. ?Underpinning? was considered as an alternative to spillway relocation during the Alpaslan 2 embankment dam design in eastern Turkey. Based on the available literature the first application of drilled piers to stabilize a spillway chute in the U.S. was at the Ralston Dam in Colorado. Ralston Dam, which is a 175-foot-high zoned fill dam located 15 miles northwest of downtown Denver, was built in the late 1930s. The concrete spillway for the dam was built on the Pierre Shale Formation in the left abutment. Since reservoir operations began, mass movements have occurred downstream of the chute area. These movements have required periodic spillway maintenance. After the occurrence of recent movements and because of high piezometeric levels, URS was contracted by Denver Water to develop a more permanent solution by the installation and monitoring of additional instrumentation, analysis of slope stabilizing measures, design, repair, and reconstruction of the distressed section of the spillway chute. With state of the art modifications that include: 1) a stabilizing berm with a toe trench that improves the global stability; 2) seepage prevention and control measures that prevent the infiltration of water; and 3) the structural support of the replaced chute section with drilled piers and reinforced concrete the probability of future displacements or other problems have been reduced for the Ralston Dam Spillway.

Jan 1, 2007

By Frank Haehnig

Ground freezing is a technique which is used more and more in tunnelling under complex ground conditions. This paper will present three case studies which highlight different aspects of the ground freezing technique when applied in urban environment. The first project is the City-Tunnel in Leipzig, Germany, which is being built beneath the central station and which is the largest ground freezing project currently under construction in Germany. The second case study is part of the North-South-Line project in Amsterdam, Netherlands where ground freezing will be carried out to al-low the TBM drive through old wooden foundation piles. The freeze tubes for this project will be driven using Horizontal Directional Drilling (HDD). The last project is the Hallandsas Tunnel Sweden where the ground freezing equipment has to be installed against high water pressure. The paper illustrates that ground freezing can be implemented in difficult ground conditions such as soft ground, highly fractured rock and high water pressure. The case studies highlight the importance of good workmanship. With the increasing numbers of large tunnels being constructed in difficult ground conditions the paper concludes that the complex case studies presented will be-come more representative for future tunnel projects in urban environments.

Jan 1, 2008

By Theodore W. Vogelpohl

Augered cast-in-place piles have proven to be effective, adaptable and economical for projects throughout the Ohio River Valley. Specifically, they have been used extensively for high-rise structures, sports stadia and large commercial developments along the Cincinnati, Ohio and Northern Kentucky Riverfront. They have been designed and utilized as relatively short toe resistance piles in bedrock, and intermediate to long toe and shaft resistance piles in granular outwash deposits above the bedrock. They have been designed for large axial compression loads as well as moderate axial tension loads and lateral loads. This paper presents a few load test results that demonstrate the range of capabilities of augered cast-in-place piles in the variable subsurface profile along the Cincinnati, Ohio/Northern Kentucky Riverfront.

Jan 1, 2005

By Garland Likins

High strain PDA testing has become common for verification of capacity of both driven and bored piles. It is equally applicable to Augered-Cast-in-Place (ACIP) Piles. It also evaluates other aspects of the installation such as integrity. The benefit of high strain dynamic test results for the relatively low cost of the tests compared to conventional static testing has resulted in widespread use. The method is described and specific procedures for testing ACIP piles are outlined. Example results demonstrate the application.

Jan 1, 2000

By Michael T. Lambert

The purpose of the this paper is to demonstrate the benefits of using additional instrumentation during load tests of auger-cast-in-place piles. Traditionally, only load and butt displacement are determined during load tests. The results from and methods used to instrument 15 auger-cast-in-place (ACEP) piles as part of six projects are included herein. By instrumenting the piles, the distribution of load along the pile length and load transfer can be determined, allowing the pile capacity to be adjusted or the length/diameter of the pile to be adjusted for the a given required load. The majority of the piles tested were designed as end bearing piles on either shale or limestone bedrock. No discussion of Geotechnical Instrumentation can be started without acknowledgement of the "Red Book." The actual title of the book is Geotechnical Instrumentation for Monitoring Field Performance, by Mr. John Dunnicliff, John Wiley and Sons, 1993. Anyone undertaking an instrumentation program should thoroughly review the Red Book, paying particular attention to Chapters 3 and 4. Instrumentation should not be done just because it can be done. There must be an unanswered question or questions that can be answered with measured data before instrumentation should be considered.

Jan 1, 2000

By T. G. Davies

The paper presents design equations for singly laterally loaded piles embedded in sand. These equations were obtained from a comprehensive nonlinear analysis of free and fixed head piles subjected to horizontal loads. The sand is modelled as an elastic-perfectly plastic material whose strength and stiffness are proportional to depth below ground level. The soil's response is described by means of a boundary element representation of the continuum while the pile itself is created as an elastic beam. Equations for the latter are derived directly from the Bernoulli-Euler theory and are coupled with those describing the non-linear soil response. The effects of bearing failure along the front, face of the pile, shear failure along its sides and tension failure at the back face are accounted for in the analysis. Simple equations are presented to describe both the elastic and inelastic responses. The only sol parameters required to use these equations are the angle of internal friction of the sand and a parameter characterizing the rate of increase of the sand's modulus with depth. The latter can be taken as equivalent to the modulus of subgrade reaction. The results of this analysis show that soil yielding is very significant at working load levels, resulting in substantial increase in bending moments and lateral deflection.

Jan 1, 2010

By Joram M. Amir

During recent years, the integrity testing of piles has made considerable progress. With the availability of portable and powerful computers, practically all integrity testing equipment is now digital. Using sophisticated software for data acquisition and analysis, today's testing systems can provide owners with important information regarding both the length and integrity of piles and drilled shafts. This sophistication carries a price: Very few clients, including experienced engineers, do understand the strange-looking graphs adorning the reports they get. In fact, most of them will never ask, some because they are too busy to care and others because they are ashamed to show their ignorance. This situation is well exploited by a few shrewd operators of test equipment. Facing strong competition and falling revenues, they simplify their task and cut their expenses by the following means: 1. Using old equipment until it falls apart, and then some, 2. Hiring under-qualified personnel, 3. Staying on site as little as possible, 4. Eliminating the analysis and evaluation stage altogether, 5. Confirming as-made lengths and reporting no defects.

Jan 1, 1999

By Tsuyoshi Honda, Kazuhiro Kaneda, Masayuki Imai, Kazuo Konishi, Kunio Higashinaka

"In recent years, the demand for measures to control liquefaction of existing airport runways and harbor structures has increased. However, from the perspectives of constructability and cost, application of grid-form deep mixing walls to these types of structures requires the formation of wider grid spacing as compared with conventional designs. In this research, we focused on the extent of liquefaction and ground surface settling when grid spacing is made wider than conventional designs. We conducted centrifuge model tests, and confirmed the liquefaction suppression effect when grid-form modifications involving wide grid spacing are adopted under asphalt pavement. The tests were conducted under conditions that included changing the grid spacing and groundwater level. When the groundwater level was high, an increase in water pressure was observed, even within the grid. However, when the groundwater level was low, the increase in water pressure inside the grid was suppressed. We also found that if the generation of water pressure can be suppressed, the amount of settling due to liquefaction can also be controlled.INTRODUCTIONOne construction technique used as a countermeasure to liquefaction is grid-form deep mixing walls. Grid-form deep mixing walls are a construction technique for which improved grid-shaped wall bodies are built into the ground below the surface using a deep mixing method. This construction technique minimizes shear deformation by surrounding liquefied ground with improved wall bodies, thereby preventing liquefaction (Fig.1). With conventional designs, grid-form deep mixing walls determine the grid spacing that can deter liquefaction based on a ratio of the grid spacing L to the improved depth H (ratio = L/H). Ordinarily, designs are implemented with an L/H ratio of 0.8 or less (PWRI, 1999).In recent years, a demand for measures to control liquefaction of existing airport pavement and harbor structures has increased. However, when liquefaction countermeasures are implemented at these types of facilities and structures, the construction work must be implemented while the facilities and structures remain in service. Therefore, temporal and spatial constraints must be considered. In addition, unlike conventional liquefaction countermeasures, performance requirements are such that, even if some degree of liquefaction is allowed, the performance is acceptable as long as the amount of settlement is within a predetermined value. Therefore, if grid-form deep mixing walls are applied to these structures, grid spacing that is wider than conventional standards is desired."

Jan 1, 2015

By Ed Kase

Cross-hole sonic logging (CSL) has become the universal standard, nondestructive testing (NDT) method used in evaluating the integrity of foundation structures to maintain quality assurance and quality control (QA/QC) of transportation facilities and infrastructures. Tomography, based on three-dimensional cross-hole sonic logging data processing technology, offers an improvement over the techniques currently used to characterize the interior structure of drilled shafts. The underlying concept for seismic tomography is based on the principle that acoustic waves propagate at different velocities through different types of material or the same material with different physical properties. Three-dimensional velocity tomographic images provide greater detail of the interior structure, making defects easier to classify with respect to size and location within the foundation structure. By accurately classifying these defects, an engineer has the information necessary to accurately assess whether these structures meet the applicable design requirements, allowing them to repair or replace inadequate foundation structures. The end result is that the foundation structures will meet the safety and service life requirements for their project. This paper will present applications of seismic tomography, illustrating how seismic imaging can provide accurate information regarding the integrity of foundation structures.

Jan 1, 2003

By Beim Jorge, Piscsalko George

"Verifying the quality of cast-in-place foundation applications, particularly those cast under slurry, is of course important, due to its great dependency on the methodology employed and on the practices of the site personnel. Due to the techniques used to install these elements, it is usually not possible to inspect the hole prior to grout or concrete placement, but there are several Non Destructive Test (NDT) methods available to assess the integrity of the completed foundation elements. This paper will compare several NDT methods with the Thermal Integrity Profiling (TIP) method for verifying the integrity in Continuous Flight Auger (CFA) piles and Bored Piles. The Thermal Integrity Profiling method will be described and some examples will be presented where TIP testing was used to confirm the structural integrity of CFA piles and Bored Piles.IntroductionThere are several Non Destructive Test (NDT) methods available for integrity testing of foundation elements. Each of those methods has advantages and disadvantages (White et al, 2008). Some methods test the integrity based on the reflections of a stress-wave generated by low or high-strain impact, while others require tubes to be installed prior to concrete pouring, and test the integrity between those tubes, or within a small proximity of them. The former methods (especially the low-strain) are faster and more cost-effective, but are not able to detect the quadrant where the damage is located. The latter methods are able to determine the quadrant, but do not test the region outside of the reinforcing cage, that is, they are not able to determine the concrete cover. The Thermal Integrity Profiling (TIP) NDT method overcomes the limitations of these other NDT methods.Overview of Shaft Integrity MethodsUntil now, the most widely used methods to test the integrity of Bored and CFA piles were the low-strain pile integrity testing and the cross-hole ultra-sonic testing. The low-strain method for integrity testing (PIT) involves attaching an accelerometer usually to the pile top (using a putty or wax) and striking the pile surface with a handheld hammer, which causes a compressive wave to enter the pile. This wave is totally reflected when it reaches the end of the pile or a major defect, and is partially reflected when it encounters any change in crosssection, or a change in the resistance or density of the pile material. These reflections arrive at the top at a time determined by the distance and wave speed, and causes a noticeable change in the signal detected by the accelerometer. The acceleration signal is normally converted to velocity by simple integration, and sometimes the force applied by the hammer is also measured. The velocity (and force) signals can be processed by the pulse-echo method (in the time domain) or by the transient response method (in the frequency domain)."

Jan 1, 2015