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By Safwan Labanieh

An experimental set-up is specially designed to study the behavior of a friction pile of 3 cm diameter in contact with the soft clay of Mexico City in a small calibration chamber (CC) of 30 cm diameter and 50 cm height. The consolidation of this compressible clay is accomplished using a special system adapted to the CC itself to insure a good knowledge of the initial state. Loading results of the pile under a consolidation pressure of 50 kPa indicate an elastic mobilization of shear stresses at the shaft of the pile (?3 kPa for 1mm displacement) followed by a hardening plastic type behavior. Unloading-reloading results indicate a mobilization of shear stresses of the same type and of the same order of values obtained from the virgin loading stress path. Cyclic loading (?40 cycles) between 0 and 1 kPa (1/3 of the failure value) give similar results to those obtained from virgin loading.

Jan 1, 2002

By Satyajit A. Vaidya

This paper presents a case-study in the design and construction of deep foundation element supported mats for two residential towers on an18,000-square-foot site in Brooklyn, New York. Based on site sub-surface conditions, conventional mat foundations bearing on medium dense sand, having an allowable bearing capacity of 3 tsf, were originally anticipated for the 16 and 25-story towers. However, when the tower shear walls were relocated to the edges of the mat foundations due to architectural revisions, the significantly increased mat edge contact stresses applied to the soil subgrade resulted in calculated settlements of a magnitude that would adversely impact the proposed structures and the neighboring/bordering lot-line building and rail transit subway structures. To address this issue, deep foundation element supported mats were designed for the towers. The design was performed as an iterative process involving structural SAFE and geotechnical Plaxis finite element computer analysis to develop a coordinated geo-structural model of the foundation system. Initial presumptive design values of 45 pci and 445 kips/inch were used for the modulus of subgrade reaction and minimum deep foundation element stiffness, respectively. The designed foundation system consisted of 40 and 60-inch-thick mat foundations for the 16 and 25 story towers, respectively. Initially, the deep foundation elements were designed as 50-foot-long, 14-inch-diameter elements installed to sustain a maximum individual compressive load of 250 tons. The final deep foundation element design was subsequently refined to consist of a 48-foot-long, drilled and grouted IBO Titan 103/51 element designed to sustain a maximum load of 167 tons. Subsequent field load tests on the deep foundation elements confirmed element stiffness ranging from 1,040 to 1,530 kips/inch, with measured mobilized side shear of about 29 psi. The mat foundation reinforcement was adjusted for the pile stiffness values determined in the field load tests, and the deep foundation supported mats were constructed. The two towers were subsequently constructed, and have performed successfully.

Jan 1, 2010

By John Mould, Gordon Chen, Michael Oakland, William McElwee

"This paper will discuss the design analysis of sheet pile cofferdams for static and dynamic blast loads. Following construction of the new Willis Avenue Bridge across the East River between Brooklyn and Manhattan, in-river piers No. 9 and No. 10 from the former bridge were demolished, partially by explosive charges. The blast at Pier 10 was conducted first and though the demolition charge was relatively small, it gave confidence that the sheeting could be designed to resist the blast load. This paper primarily summarizes our analysis and performance of a sheet pile cofferdam at Pier 9 used to withstand the larger blast loads, contain the blast debris, and allow excavation of the pier below the existing river bed mudline. The program NLFlex was used to predict stresses and deformations of the cofferdams under dynamic blast loads, using simplified equations to estimate the underwater blast pressures. Specifically, the analysis focused on the stresses in the struts, waler beam, sheet pile interlocks and connection of the sheeting to the waler beam. Design included allowing plastic deformations and limited rupture of the sheet pile interlocks under the blast loading. Comparisons are made between stresses assessed by the dynamic finite element modeling and empirical relationships used within the industry. The performance of the system after the actual blast is discussed as well as details of the performance of welded vs. bolted connections within the system. IntroductionThe Willis Avenue Bridge is one of the major access ways from the Bronx into Manhattan. The location is shown on Figure 1. The original bridge constructed in 1901 was a swing bridge over the East River. The bridge was in disrepair and outdated with regards to its ability to handle the flow of traffic resulting in numerousaccidents.In 2007, Kiewit Constructors Inc./Weeks Marine, Inc., A Joint Venture was selected to construct a replacement bridge. The $612 million project included construction of a new bridge just to the south of the original bridge. The most notable aspect of the construction was floating and lifting the new 350 ft. long swing span in place as a single piece. However, another significant challenge was using blasting to demolish two of the abandoned piers which were within the East River. The blast would be near existing structures in both Manhattan and Brooklyn and would be within 30 ft. of the new bridge."

Jan 1, 2017

By Federico Pagliacci

"Many existing dams are subject to underwater seepage due to subsoil conditions, like deep alluvial deposits or pervious rocks or karst. Remedial works are necessary in order to install new cut-off walls to stop the water flow. In some cases the cut-off walls have to be executed at depths never reached so far, and difficult to reach with traditional foundation techniques. In many cases the Hydromill technology proved to be the best system to overpass rocky layers and ensure the required verticality. The maximum depth reached by the industry was in the range of 120-150 meters. This article describes the test performed to excavate and cast in place a 3.2x1.5 m panel to a depth of 250 m. The article will also describe the stratigraphy of the site down to 250 meters, as well as the technique adopted to achieve the said depth with deviations from verticality of 30 cm along the longitudinal axis (0.12%) and 20 cm along the transverse axis (0.10%), measured at the bottom of the excavation. The concreting of the panel, for about 1,100 m³, with plastic concrete in the lower portion and conventional concrete in the upper portion will be illustrated. Finally, the tests performed during the excavation and after concrete casting will be also described, with special attention to the continuous directional core drilling that was performed along the whole length of the panel to verify the results of the deviation from verticality, through the onboard instruments, and to control the quality of concrete at a depth never reached before. IntroductionMany existing dams are subject to underwater seepage due to subsoil conditions, like deep alluvial deposits or caves and cavities or acid solutions in the bedrock formations.Conventional remedial works generally consist in the construction of an additional cut-off wall throughout the dam body and the subsoil, in most cases being deeper than the original one. Today, many examples of successful remedial cut-off walls allow the engineers to design the most suitable solution according to the dam and subsoil characteristics and nature.The real difficulty stems from the depth at which the new cut-off wall has to be socketed in competent rock or soil, so as to eliminate underwater seepage. The maximum depth ever achieved with a cut-off wall is 122.5 m for the remedial work of Mud Mountain Dam, Washington, USA, in 1988-1990. This 0.85-1.0 m thick cut-off wall was realized by means of a Hydromill, by excavating single 2.8 m-wide secant panels."

Jan 1, 2017

By A. V. Rose

A redevelopment in the City of London has been constructed with a piled foundation system that is believed to be the first of its kind. The purpose of the research is to explore this novel foundation method, which involves the installation of closely spaced piles in a perimeter arrangement with a body of soil enclosed in the centre. Both centrifuge modelling and numerical modelling techniques are used.

Jan 1, 2011

By A. B. Cerato, M. K. ElSawy, A. Elgamal

"Helical piles are gaining popularity as foundations for new construction as well as retrofitting option for deficient foundations. More recently, large diameter helical piles are used to support structures in regions characterized with high seismic hazard. Even though they have proven to be viable in seismic areas such as New Zealand, where they experienced little damage during the Christchurch earthquake, the knowledge about their seismic analysis and performance is largely lacking. Therefore, there is a need for comprehensive study to evaluate their performance under seismic loading. The current objective of this study is to investigate the performance of helical piles through a full-scale testing program that was performed at the NEES/UCSD Large High Performance Outdoor Shake Table (LLHPOST). The experimental setup involved ten steel piles of different configurations installed in dry sand. The piles were loaded with different masses and were subjected to different earthquake signals to simulate different dynamic behavior. This paper compares the performance of different moment curve fitting methods used to interpret the test data. Furthermore, the effects of different frequency content of loading on the pile response is illustrated in terms of deflection along the shafts of tested piles with different configurations.INTRODUCTIONEarthquakes are a major hazard for structures situated in seismic regions, and dynamic loading must be a design consideration. Successful design of a foundation system entails providing a safe and economic foundation solution to resist earthquake loading. Different foundation options have been used to support buildings in high seismic regions. Helical piles represent a viable foundation option that offers several advantages in terms of ease of installation, lower cost and environmental impact, ability to approximate the axial capacity directly from torque readings and more (Perko 2009). However, they are not typically considered as an option in many seismic regions. Meanwhile, several buildings supported on helical piles in New Zealand have survived the Christchurch earthquake with negligible damage, which encourages performing further research to understand the behaviour of these piles under seismic loading.A helical pile consists of a steel shaft fitted with a steel helix/helices. The helical pile is installed by applying torque to its head via mechanical torque. Nowadays, helical piles are used in a wide range of applications such as foundations for light posts and residential houses. The static behaviour of helical piles has been studied extensively and is relatively well understood (Tsuha and Aoki 2010; Mittal et al. 2010; Sakr 2011; Elsherbiny and El Naggar 2013; El Sharnouby and El Naggar 2012; Elkasabgy and El Naggar 2015; Weidong et al. 2015 and Bagheri and Naggar 2015) However, the dynamic and seismic behaviours of helical piles is seldom investigated (Elkasabgy and El Naggar 2013). This underscores the knowledge gap currently present regarding the seismic behaviour of helical piles."

Jan 1, 2017

By Masaki Kitazume

"Many earthquakes take place every year in Japan, in which the 1995 Hyogoken-Nambu earthquake and the 2011 Tohoku earthquake induced both a humanitarian crisis and massive economic impacts. As liquefaction which occur in a loose and saturated sand layer, induces quite large damages of infrastructures, the importance of liquefaction mitigation has been emphasized to minimize earthquake disasters for many years. Many kinds of ground improvement techniques based on various improvement principles have been developed for earthquake disaster mitigation. Among them, the grid type deep mixing method has been often applied to liquefaction mitigation. In the method, the stiff grid walls are constructed by mixing the soil and binder in-situ, which are expected to restrict the shear deformation of the soil within the grid walls so that the pore water pressure generation can be remained small. The high applicability of the method was confirmed in several earthquakes, including the 1995 Hyogoken-Nambu earthquake and the 2011 Tohoku earthquake. In this paper, the development of the method, some applications of the deep mixing method to earthquake disaster mitigation are briefly introduced. INTRODUCTION In Japan, many earthquakes take place every year in Japan, in which the 1995 Hyogoken-Nambu earthquake and the 2011 Tohoku earthquake induced both a humanitarian crisis and massive economic impacts. As liquefaction induces quite large damages, the importance of liquefaction mitigation has been emphasized to minimize earthquake disasters for many years. Table 1 shows the amount of damage to port facilities (Noda, 1991). According to the table, the amount of damage when liquefaction takes place is about 20 to 50 times larger than that without liquefaction. This highlights the importance of liquefaction mitigation to minimize earthquake disasters. There are many kinds of soil stabilization techniques developed for liquefaction in Japan. Among them, the deep mixing method (DMM), an in-situ cement stabilization techniques, was developed in 1970s in Japan and has frequently been applied to improvements of clayey and sandy soils (Kitazume and Terashi, 2013). The grid type DMM has been often applied to prevent liquefaction, where the grid of stabilized column walls function to restrict generation of excess pore pressure in the soil within the walls by confining the soil particle movement. The improvement effect of the method was first evaluated in the Hyogoken-Nambu earthquake in 1995 and was also evaluated in the Tohoku earthquake in 2011. In this paper, some successful performance of the deep mixing method to earthquake disaster mitigation in the two earthquakes are briefly introduced."

Jan 1, 2015

By Waddah Akili

The demand on pile installation in the offshore of the Arabian Gulf has, over the last two decades, experienced unprecedented boom, triggered by the construction of platforms, to help facilitate the production and transport of oil and gas. Available borehole data show that ground conditions for pile installation in the offshore is highly variable, resulting in misassessment of insitu conditions, leading to a huge discrepancy between ultimate pile capacities, based on design, and actual capacities after installation. The paper makes use of pile installation records derived from several platforms in the offshore of the state of Qatar, the Gulf Region. More specifically, the paper evaluates “as–installed” ultimate capacities and safety factors, recommends remedial installation procedures, and proposes a means for determining pile acceptability for piles meeting refusal short of design penetration. The paper offers what is believed to be relevant recommendations to guide the design and installation of future offshore structures; enabling the geotechnical community in the Region to solve their current offshore pile installation problems and gain an added margin of confidence regarding the ultimate capacity of installed piles.

By Jeremy G. Kress

We propose the discrete element method (DEM) as a complimentary alternative to analytical solutions and FEM models for the analysis of pile response. DEM is a novel approach to the engineering design of deep foundations which can be used to provide insight into the mechanics of soil-soil and soil-structure interaction. It is common to use analytical, empirical, and semi-empirical methods to predict pile behavior, where if granular properties, pile length, or load orientation change, then significant adjustments are made in the design sequence. DEM provides a more uniform approach in granular soils. Based on constitutive force-displacement relationships and laws of motion in rigid and elastic bodies, few changes must be made for a wide variety grain types, pile types, embedment, and load orientation. Preliminary results for simulation of a single pile are qualitatively consistent with results from conventional design procedures and also provide significant information not available from other analyses (e.g., local information about interface failure during shear). Importantly, these analyses are portable to a variety of pile types and installation procedures, which may not be the case for empirical approaches. Given consistent increases in computing power and rapid advances in model speed and sophistication, the DEM should prove to be a robust method for design and the analysis of pile response in granular soils.

Jan 1, 2010

By Lance Helwirg

New high and low double outfall bridge structures for a juvenile fish bypass system have been constructed on the Washington Shore approximately two miles downstream from the Bonneville Dam on the Columbia River. The high and low outfalls each extend approximately 400 feet into the river from the Washington shore and are designed to release juvenile salmon into the river at above-water discharge elevations for improved survival rates. The two outfall structures include post-tensioned concrete double box flume girders approximately 7 feet high by 13 feet wide, which will be submerged in river flows as high as 15 feet per second. Each of the 6 offshore foundation piers is composed of a single 10-foot diameter reinforced concrete drilled shaft with a permanent steel casing embedded into the river bottom approximately 100 feet. Challenging outfall design conditions included designing the entire structures to be submerged for long periods of time in 15-feet-per-second river water flow with a 60-foot cantilever at the end of each outfall, and with the superstructure 70 to 80 feet above the river bottom. Figures 1-1,1-2, and 1-3 show the high and low outfall structure overhead photos and elevation view.

Jan 1, 2001

By Rae Mackay, Kaveh Ranjbar Pouya, Ali Tolooiyan

"A major part of Melbourne’s central business district is underlain by a very soft silty clay deposit known as Coode Island Silt (CIS). Due to the low strength of CIS, most construction in the region is based on pile foundation systems. Traditionally, the design of pile foundations is mostly based on empirical and analytical methods. However, numerical methods such as Finite Element Methods (FEM) can be utilised for more accurate estimation of the bearing capacity and deformation of pile foundation systems, especially in complex loading scenarios. Unfortunately, no systematic effort is made yet to calibrate a realistic nonlinear constitutive model to describe the geomechanical behaviour of CIS in a numerically based solution. Among the nonlinear constitutive models, the Hardening Soil (HS) model is an advanced hyperbolic model which accounts for the nonlinearity of stress-strain relationship as well as the stress dependency of the soil stiffness. In this study, the HS model is calibrated based on laboratory tests performed on CIS. Also, to validate the accuracy of the calibration, the wellknown cavity expansion theory is employed to model the CPT cone tip resistance (qc) in CIS, and results are compared against the measured CPT qc profile at the field.INTRODUCTIONA large percentage of world’s coastal areas are covered with soft marine clay deposits. Having very low shear strength and high compressibility, the alluvial deposits are known as one of the most problematic soil layers for the design and construction of infrastructure facilities. A major part of Melbourne’s central business district is underlain by a very soft silty clay deposit known as Coode Island Silt (CIS). Basically, there are two main solutions for construction in such weak soil conditions. One is the use of pile foundations transferring the applied load to deeper and stronger soil layers, and the second one is to employ ground improvement techniques such as using deep soil mixing columns to improve the bearing capacity of the soil. In both cases, a practical geotechnical design should incorporate both stability analysis and deformation analysis to achieve a cost-effective and reliable solution. Most of the classic solutions for stability analyses such as limit equilibrium analysis disregard the stress-strain relationship of the soil for the sake of the simplicity (Chen, 2007; Sokoloviskii, 1965). In a similar simple approach, most of the past studies of deformation analysis have been established on the basis of linear elasticity. However, it is well recognised that the soil stress-strain behaviour is highly nonlinear even at very small strains (Burland, 1989). Hence, for a precise deformation analysis of the foundation of important geotechnical structures, the application of advanced nonlinear constitutive models is extremely beneficial. Precise deformation analysis is essential as geotechnical designers have to predict the displacement of geotechnical structure and the adjacent soil as well as the induced displacement and forces to adjacent structures. This issue is more highlighted recently in the analysis, and design of highly important infrastructures as geotechnical engineers are facing new challenges in the analysis and design of infrastructures in congested areas. Rapid population growth, especially in the major cities all around the world necessitates the design and construction of more integrated infrastructure facilities. Consequently, geotechnical engineers should employ more advanced design approaches to address the new challenges in geotechnical engineering practice. Complicated geometries, different loading scenarios and the application of nonlinear deformation models which is believed to be essential for a precise deformation analysis, necessitate the application of numerical methods to satisfy most of the design requirements."

Jan 1, 1900

By Rajarshi Pramanik, Nirjhar Dhang, Dilip K. Baidya

"This paper performs the reliability evaluation of pile foundation under vertical loading condition using the concept of fuzzy set theory. The uncertain parameters are expressed as fuzzy numbers. Monte Carlo simulation technique in conjunction with fuzzy set theory and fuzzy reliability index approach are implemented in evaluation of the probability of failure of pile foundations. The results are validated through some well established methods such as, First Order Reliability Method (FORM), Second Order Reliability Method (SORM), and direct Monte Carlo Simulation (MCS). Response surface method (RSM) is used to approximate the original limit state equation through second order polynomial. The effect of the position of the water table is also highlighted. Finally, the effect of the variation of applied load is examined and it is observed that the fuzzy reliability analysis gives more conservative estimate of failure probability than the other methods.INTRODUCTIONCivil engineering structures, such as high rise buildings, bridges, offshore platforms etc. are always subjected to vertical as well as horizontal loads. To support these structures, pile foundations are generally the solution in most of the situation. It transmits load from the superstructure to soil at a reasonably great depth. This transfer may be by vertical distribution of the load along the pile shaft or a direct application of load to a lower stratum through the pile tip. Different methods are available to estimate the capacity of piles embedded in different types of soil and under the application of vertical and horizontal loading. To consider the variability in soil and other unforeseen able situation, generally a reasonable value of factor of safety is used to estimate the designed capacity of the pile. Recent developments have shown a trend to place the treatment of uncertainty on a more formal basis, in particular by applying the results of reliability theory to geotechnical engineering. Keeping in mind the importance of pile foundation in the engineering structures it is essential to maintain a high structural safety which result in increase in reliability. The probability theory has been proved to be a powerful tool for representing variability in mathematical models. The variability associated with soil parameters and the modeling uncertainties are needed to be considered for the reliability assessment purpose.Recent development (Zhang et al. 2005; Misra and Roberts 2006; Haldar and Babu 2008; Basu and Salgado 2012; Teixeira et al. 2012; Pula and Rozanski 2012; and Chan and Low 2012) showed that the reliability analysis of pile foundations subjected to axial as well as lateral load has been one of the important current research topic in geotechnical field. Probabilistic based performance criteria were quantified for a single pile and pile groups in cohesionless soil by Eloseily et al. (2002). A p-multiplier approach was incorporated into the analysis to modify the p-y curve for a single pile to obtain the p-y curve for individual piles in a pile group. A statistical analysis of set up capacity of pile was carried out from the database of a large number of pile testing data in clay by Yang and Liang (2006). Load and resistance factor design (LRFD) using FORM was used for examining the different load and resistance factor for different target reliability index. Limit state analysis of drilled shaft was performed by Misra and Roberts (2006) in probabilistic framework. The fuzzy based reliability analysis (Dodagoudar and Venkatachalam 2000; and Park et al. 2012) of the earth slope was reported in the literature. Dodagoudar and Venkatachalam (2000) presented a new approach, called fuzzy point estimate method (FPEM) for reliability evaluation of earth slope. Park et al. (2012) reported a hybrid approach, fuzzy set theory in conjunction with Monte Carlo simulation technique, to determine the failure probability of earth slope. Second Order Reliability Method"

Jan 1, 2015

By John P. Turner, Benjamin J. Turner

"This report describes a research project for evaluating the applicability of the widely accepted 80 percent criterion for elongation of ground anchors to anchors with unbonded lengths exceeding 100 feet. This issue is driven by several recent projects involving ground anchors for landslide stabilization in which a significant percentage of the anchors did not meet the criterion that requires measured elongation during proof load testing of at least 80 percent of the theoretical elastic elongation. The projects involved anchor unbonded lengths in the range of 85 to 220 feet, which is outside the range traditionally used in practice, although anchors of this length are being used more frequently for landslide stabilization. The principal objective of this research is to address whether the widely accepted criterion of 80 percent elongation is applicable for such applications, and whether other factors affect the ability of anchors to meet the criterion.Analytical methods for predicting transfer of load along the length of steel strand due to friction loss are used routinely in the prestressed concrete industry. These analytical expressions provide a rational framework for quantifying changes in load due to friction along the length of a ground anchor in terms of a ‘wobble coefficient’ (K) as defined in Aalami (2004). Values of the wobble coefficient for ground anchors can only be determined by back-calculating from load tests, i.e., fit the value of K to the appropriate analytical expression based on the known test load and measured percent elongation. The analytical basis is first developed and shown to provide a tool for evaluating results of anchor load tests to determine the magnitude of expected elongation as a function of unbonded length. Next, a database of anchor load tests is used to back-calculate values of K for anchors with unbonded lengths in the range typically used in geotechnical applications (< 100 feet). These values of K are then used to calculate expected friction loss for anchors with high unbonded lengths (100 to 250 feet) to evaluate whether the 80 percent criterion is reasonable."

Jan 1, 2017

By Thomas G. Tavernaro, Jeffrey A. Schaefer

"The $106 million Olmsted Approach Walls Project, completed in the spring of 2004 by Massman Construction Co., Kansas City, MO, is one phase of a new $1.4 billion Corps of Engineers locks and dam facility located at Mile 964 on the Ohio River, approximately 17 miles (27.4 km) upstream of its mouth at the Mississippi River. When completed, the Olmsted Locks and Dam (Figure 1) facility will replace two aging locks and dams (Locks and Dams 52 & 53) built in the 1920’s, and produce an estimated $600 million annual economic benefit to the nation through reduced lockage time and operation and maintenance costs. PROJECT OVERVIEWThe Olmsted Approach Walls Project consisted of “in-the- wet” construction of four fixed nose pier structures, four floating concrete approach walls, one fixed wall and related underwater excavation, grading and stone placement. Over 12,000 tons (11,000 tonnes) of structural steel and pre-cast concrete elements, up to 335 tons (304 tonnes) in weight, were safely erected during the project.To support these massive structures, the Louisville District of the U.S. Army Corps of Engineers teamed with INCA Engineers, Inc., Bellevue, WA to design thirty seven 10’ (3m) diameter shafts (cast-in-place steel-shell piles) capable of maintaining elastic behavior below ground while resisting barge impact loads, extreme head-on collisions from runaway tows, and environmental forces from river current, wind, and seismic events.The shafts (typically 150’ (45.7m) in length) were founded 100’ (30m) into the riverbed through alluvium, a very consolidated fine sand and clay Cretaceous soil, and finally into a hydrothermally altered rock. Thirty seven shafts were installed under open river conditions at the site, a group of four shafts at each nose pier-pylon location (Figure 2), and 21 at the fixed land wall. Due to difficulty in achieving the required casing tip elevation the team developed a design modification that was successfully implemented for 27 of the shafts.Concurrent with the work at Olmsted, eleven pontoon segments for the four floating approach walls were constructed at a graving yard in Paducah, KY, developed by Massman Construction Company specifically for the project. While the pontoon geometry varied, the pontoons averaged 350’ (107m) in length, 40’ (12.2m) in width and weighed 4,500 tons (4,082 tonnes). The longest of the four walls, at 1,700’ (518m) was comprised of five interconnected pontoons."

Jan 1, 2006

By Anthony T. C. Goh

"For deep excavations in soft clay, it is common to use jet grouting piles (JGP) prior to excavation to minimize wall deflections and ground settlement, and to prevent basal heave instability. In this paper, finite element analyses were carried out to assess the basal heave factor of safety for excavations in soft clay supported by JGP. Comparison of the factor of safety from the finite element analyses with limit equilibrium methods was then performed. Subsequently, to account for the uncertainties in the soil and JGP properties, a simplified reliability analysis procedure is proposed to estimate the probability of basal heave failure for deep excavations supported by JGP.INTRODUCTIONJet grout piles (JGP) are often used to prevent basal heave instability and to minimize excessive wall and ground movements associated with deep excavations in soft clay deposits (Shirlaw 2003; Wen 2005; Ou 2006). The jet grouting process which is carried out prior to any excavation works produces a series of short overlapping grout columns resulting in a “continuous” base slab (commonly termed as jet grout pile or JGP) below the final excavation level that spans across the entire excavation (Gaba 1990; Hsieh et al. 2003; Ho and Hu 2006). Typically, the JGP thickness ranges from 2 m to 4 m.The focus of this paper is on the assessment of basal heave instability for deep excavations in clay stabilized with JGP. Finite element analyses were first conducted to determine the basal heave factor of safety for deep excavations in clay with JGP. Comparisons were then carried out with factors of safety based on conventional limit equilibrium methods. Since the conventional factor of safety approach does not explicitly reflect the uncertainties of the soil and JGP properties, it is demonstrated in this paper that a simple reliability based approach (Hasofer and Lind 1974) can be used to assess the probability of basal heave failure.LIMIT EQUILIBRIUM METHODFor excavations is clay, the Terzaghi (1943), Bjerrum and Eide (1956) and Eide et al. (1972) methods which are based on bearing capacity theory, are commonly used to determine the basal heave factor of safety. Another commonly adopted method in Japan and Taiwan is the slip circle method which involves taking moments about the lowest strut level (JSA 1988; Hsieh et al. 2008; Luo et al. 2012). The slip circle method has also been applied for excavations with a JGP at the base by incorporating the undrained shear strength of the JGP. In the slip circle method, the basal heave factor of safety FSslip is assessed by taking moments about the lowest strut level (Fig. 1)"

Jan 1, 1900

By Michael Oakland

This paper will discuss the design analysis of sheet pile cofferdams for static and dynamic blast loads. Following construction of the new Willis Avenue Bridge across the East River between Brooklyn and Manhattan, in-river piers No. 9 and No. 10 from the former bridge were demolished, partially by explosive charges. The blast at Pier 10 was conducted first and though the demolition charge was relatively small, it gave confidence that the sheeting could be designed to resist the blast load. This paper primarily summarizes our analysis and performance of a sheet pile cofferdam at Pier 9 used to withstand the larger blast loads, contain the blast debris, and allow excavation of the pier below the existing river bed mudline. The program NLFlex was used to predict stresses and deformations of the cofferdams under dynamic blast loads, using simplified equations to estimate the underwater blast pressures. Specifically, the analysis focused on the stresses in the struts, waler beam, sheet pile interlocks and connection of the sheeting to the waler beam. Design included allowing plastic deformations and limited rupture of the sheet pile interlocks under the blast loading. Comparisons are made between stresses assessed by the dynamic finite element modeling and empirical relationships used within the industry. The performance of the system after the actual blast is discussed as well as details of the performance of welded vs. bolted connections within the system.

By Filippo Maria Leoni, George Filz, Wesley Schmutzler, Matteo Bertoni

"The US Army Corps of Engineers selected the Deep Mixing Method (DMM) for the required stabilization at the LPV 111 Project (New Orleans, USA). DMM was used for ground improvement/foundation strengthening and consequently to stabilize and support the burden of the new levee. Two different technologies were used: Trevi Turbo Mix (TTM) and Contrivance Innovation Cement Mixing Columns (CI-CMC). LPV 111 is the largest soil mixing project to date in the USA with its more than 18,000 elements installed to a depth of up to 67 feet for a total of 1.7 million cubic yards of treated soil. The preparation and execution of the project presented many challenges from various points of view. The little time available to complete the job led to the simultaneous utilization of eight deep mixing rigs and batch plants which worked 24 hours per day, 5.5 days per week on a stretch of land approximately 5.3 miles long. Given the imposing geographical extent of the project, a four phase laboratory programme and five field validation test programmes, conducted in as many different areas of the project, were completed to design and optimize the grout mixes and the installation parameters. The massive quality control/quality assurance testing programme produced over 500 drilled core holes and over 5,000 tested specimens in order to determine unconfined compressive strength (UCS) and uniformity of the DMM elements. This paper has the purposes of describing the tremendous challenges encountered and providing valuableinformation that may be useful for other future projects, including details not previously published.INTRODUCTIONReach LPV-111 is part of the Lake Pontchartrain and Vicinity Hurricane Protection System designed to protect the city of New Orleans and the surrounding areas from the surge that would accompany a 100 year hurricane event. LPV-111 measures approximately 8.5 km (5.3 miles) long, of which 7.2 (4.5 miles) extend along the north bank of the Gulf Intracoastal Waterway (GIWW) and the remaining 1.3 (0.8 miles) run north and terminates at the CSX Railroad Gate. The Bayou Sauvage National Wildlife Refuge borders the levee on both sides (Fig. 1)."

Jan 1, 2015

By Jonathan J. Dewsbury

It is argued that approximate computer based methods are only suited to modelling conventional piled rafts, for pile enhanced rafts where the interactions will be non linear three dimensional finite element analysis is required. However current 3D finite element analysis often relies on symmetry to reduce computational cost and there are concerns over the dependency of the results on the user. Therefore a new strategy within the finite element framework has been proposed. The main advantage of this strategy is that each stage of the model can be checked for consistency. There is also the added benefit that non symmetrical models can easily be constructed by tying the validated components together without dramatic increases in computational time. The proposed strategy compared well to the published results of a hypothetical example of a piled raft previously analysed with numerous methods by Poulos et al. (1997).

Jan 1, 2010

By John Davie

We used a Remtek survey in Glenrock and had very good luck with it when we first started the initial investigation. We would have loved to have used that more but my understanding is the equipment is hard to find. It also requires a flooded mine workings. If you&apos;re in a dry mine the communication between the two holes is not quite as successful.

Feb 10, 2003

By Slav Tchepak

The King&apos;s Wharf development is located in Sydney&apos;s Darling Harbour area. The site was originally used for industrial maritime purposes, which over the years has been reduced to accommodating leisure craft only. The site has been filled with various materials, resulting in fill materials varying from soils, to concrete and rock fill. A prestigious new residential development at the site required piles to found in Sydney sandstone that occurred at depths ranging from 1 to 27m. The selection of appropriate pile types is discussed, as are details relating to the design and construction of cast insitu Omega piles and CFA piles. A number of issues needed to be addressed relating to the piling, including the design of the piles, the potential for liquefaction of the fill material due to earthquakes, penetration of the piles through the fill materials, installation of the piles to a satisfactory positional tolerance and pile performance. A number of piles were dynamically tested to prove pile performance and these results are presented and compared with design expectations. The project was successfully completed on time and budget, indicating the selection of pile types in the difficult ground conditions to be appropriate.

Jan 1, 2000