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By Sudip Basack

"The topic of pile foundation subjected to lateral cyclic load is an age-old problem confronted by Geotechnical Engineers. The environment prevalent in ocean and shorelines necessitates the piles supporting offshore and onshore structures to be designed accounting for the lateral cyclic loading resulting from the effects of sea waves. The quasi-static nature of this type of loading induces remarkable deterioration in the interactive performance of the soil-pile system. This can be manifested as progressive loss in pile capacity associated with increased pile head deflection. The work reported herein is aimed towards conducting rigorous theoretical analysis using finite difference technique so as to analyze the lateral cyclic loading response of a single, vertical pile embedded in cohesionless soil. The theoretical results are compared with the experimental results and reasonably good agreement is noted. This paper presents a brief description of the theoretical analysis carried out with some typical results and the relevant conclusions drawn therefrom. 1. INTRODUCTIONOffshore structures, namely, quay & harbour structures, jetties, tension leg platforms, oil drilling platforms, etc. are largely supported on pile foundations. Apart from usual loads from superstructures, these piles are subjected to continuous action of wave loading. This type of lateral loading is quasi-static cyclic in nature which results in considerable degradation in the interactive performance of the pile-soil system initiating progressive reduction in pile capacity associated with increased pile-soil stiffness. This may ultimately lead to disastrous consequences.Amongst limited research works in this field, the major contributions are made by Matlock (1970), Idriss et al (1978), Poulos (1982), Vucetic et al (1988), Long & Venneste (1994) and Basack (1999). A brief review of these works indicates that the degradation of the pile-soil system under lateral cyclic loading mainly depends upon the following parameters: number of cycles, frequency (cycles per unit time), cyclic load level (ratio of cyclic load amplitude to the lateral static ultimate pile capacity, in case of loadcontrolled mode) and cyclic displacement level (ratio of cyclic displacement amplitude applied at the pile head to the external pile diameter, in case of displacement-controlled mode). As pointed out by Poulos (1981 & 1982), the degradation is mainly due to: 1) partial to zero dissipation of excess pore water pressure generated during cyclic loading in progress, 2) destruction of interparticle bond with particle realignment and 3) rearrangement and gradual accumulation of permanent plastic deformation around pile"

Jan 1, 2005

By Kevin Kuhl

With the destruction of the US-90 Bridge spanning St. Louis Bay by Hurricane Katrina, the State of Mississippi awarded its first major design-build contract in order to have a completed four-lane bridge in a period of less than two years. The structure consists of 76 pre-cast concrete beam spans with a total bridge length from Bent 1 to Bent 77 of 11,124 ft (2.1 miles). All 77 bents are founded on pre-cast, pre-stressed concrete piles and consist of two foundation types: pile bents and water line footings. A total of 53 pile bents were utilized where the deck is less than 52 ft above the water. Further divided, 10 pile bents, supported by 24 in. square, solid piles, are located on land. The remainder of the pile bents are located within St. Louis Bay and supported by 36 in. square, voided piles. All the waterline footings are supported by 30 in. square, voided piles. In total, 138 -24 in., 437 -30 in., and 463 -36 in. piles support the structure. Production pile design was based upon information gathered from the subsurface investigation, design soil profile and 23 out-of-position test piles. Verification of the design was established by monitoring the first production pile driven at each bent using the Pile Driving Analyzer. Particular challenges included highly variable coastal deposits, loads in excess of 1600 kips per pile and a compressed construction schedule. Initial drive capacity of a portion of the production test piles was less than expected resulting in a minimum 14 day setup. Following the setup period, restrikes were necessary to verify capacity. Project production piles ranging from 50 ft in length to in excess of 160 ft in length were used to achieve the required resistance. This paper includes a brief overview of the foundation design and indicator test pile program. The main objective is to provide a summary of the quality control procedures including establishing the driving criteria for each bent and to present issues that arose during production pile driving and the solutions that followed.

May 11, 2007

By Paul Doherty

It is known that the axial capacity of a displacement piles installed in clay varies with time. Consolidation theory suggests that dissipation of porewater pressure set-up during pile installation would lead to increased effective stress and hence higher pile resistance. In recent years a number of case histories have reported time dependent capacity increases for piles installed in sand. Although there is some debate regarding the physical mechanisms controlling this phenomenon, known as ageing, it is unrelated to pore pressure dissipation as piles in sand are installed in primarily drained conditions. A series of field tests designed to investigate ageing effects in soft clay are presented in this paper. Full-scale load tests on 6m long 250 mm square concrete piles, which were driven into soft clay are described. The piles were first tested approximately 100 days after installation, at which stage full equalization of the excess pore pressures had occurred. Static load tests were then performed up to 10 years after pile installation. The piles exhibited significant ageing, with their shaft resistance increasing by up to 66% over a 10 year period. Possible mechanisms for such aging characteristics are explored.

Jan 1, 2011

By Jeremy Butkovich

Dynamic soil-structure interaction (DSSI) analyses are becoming more common in bridge designs, especially in seismically active areas. Because of its proximity to two active fault zones, the Evergreen Point west approach bridge replacement will be base isolated, and will be designed using DSSI. The project team completed two independent bridge designs to satisfy peer review requirements. The designs required substantial characterization of the soil dynamic behavior using both laboratory and in-situ testing. The analyses made use of earthquake time histories spectrally matched to conditional mean spectra. This led to reduced, and more realistic seismic demands on the structure, compared to conventional uniform hazard spectrum matching. The bridge analyses suggest that the preliminary bridge design is relatively conservative. This will allow the design team to potentially reduce shaft/column diameters and reinforcement. The design team estimates that the dynamic analysis design could represent a net savings of around $60 to $90 million compared to a conventional design.

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 Tomohiro Yamasaki

"At the pre-construction foundations of the controlled waste disposal site built at the Port of Kinuura, the clayey soil account for the most, and with lesser amounts of sand compaction piles and sand mat. The cement deep mixing method (CDM) was used to improve ground impermeability and to reinforce the foundations on the seawall. Laboratory mixing and testing was performed to determine the appropriate quantities of cement additive for clayey soil, SCP sand, and sand mat. The test results indicated that maintaining the design strength of qu = 1,550 kN/m2 would require C = 100 kg/m3 of cement additive for all three soil types (clayey soil, SCP sand, sand mat). The permeability performance needed to improve ground impermeability assumes a permeability coefficient of K = 1.0×10-6cm/s. And the clayey soil satisfied the performance requirements at C = 100 kg/m3. However, to improve grand impermeability of the SCP sand and sand mat required more than 5% of particles having diameters of less than 75 µm. Thus, in the latter two cases, the required cement adding quantity was C = 250 kg/m3. The test specimens at one to two weeks after the created with a permeability coefficient of K = 10-6cm/s became permeability coefficient of K = 10-7cm/s six week later due to the effects of cement solidification. So the permeability coefficient declined about one order. The permeability coefficient three months later tends to decline continued with a somewhat lower.INTRODUCTIONBetween 2008 and 2011, the Aichi Seaside Environment Center constructed the Kinuura No. 3 offshore controlled waste final disposal site at Taketoyo in Aichi prefecture. (see Figure 1). The disposal site offers a landfill capacity of 5.21 million m3 and measures 472,000 m2 in area, of which some 344,000 m2 is a managed controlled sector enclosed within an impermeable seawall."

Jan 1, 2015

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 Gihan E. Abdelraham, Youssef G. Youssef, Mohamed M. Kamel

"Previous studies defined Narrow Mechanically Stabilized Earth, NMSE, walls as a retaining wall with aspect ratio (wall width to its height, L/H) less than 0.70 as in traditional walls. Some studies investigated its behavior and its failure planes compared to those of traditional walls. In this paper, parametric study using finite element analysis PLAXIS, 8.2 has been introduced to discuss global factor of safety, FS, maximum horizontal displacement, Ds, maximum tension force of reinforcement element, Tmax, and active earth pressure coefficient, ka, as a function of different aspect ratio of NMSE wall, L/H, reinforcing elements spacing, S, elastic axial stiffness of reinforcement element, EA, wall batter, 1/m, soil friction angle, f, and wall height, H. The results indicated that increasing aspect ratio increases the factor of safety, maximum horizontal displacement, maximum tensile force and active earth pressure. Increasing elastic axial stiffness increases factor of safety, maximum tension force of reinforcement element while decreasing the maximum horizontal displacement.IntroductionReinforced earth is a composite geoconstruction material, which embodies two basic components; namely engineering fill and reinforcing elements. The latter one is responsible for improving the tensile and shear resistance of the soil. The soil-reinforcement technique has been in use for many geotechnical applications especially MSE walls.A narrow wall system is referred to as a MSE wall with an aspect ratio, L/H, below 0.70 that is placed in front of a stabilized wall. An example of a narrow wall system with its dimensions is illustrated in Fig. 1."

Jan 1, 2017

By Matthew Janes

The new Bow office complex will become the new headquarters of EnCana Corporation, a leading Canadian oil and gas company. The shoring system, encompassing nearly two city blocks and excavated to a depth of 20.5 m, supported surrounding utilities and buildings in downtown Calgary. Past excavations in the area experienced large amounts of rock movement, the mechanics of which were poorly understood. The focus of this paper is the design process and construction results concerning rock movement and the effectiveness of the shoring structure. A lack of information regarding the local in-situ stresses and shear band propagation in the bedrock led to research of case studies in the Calgary area and a peer review from local experts. Several geotechnical scenarios were analyzed using FLAC to account for varying residual rock stresses and the location and composition of weak rock layers suspected of causing shear band movement. Movement characteristics were predicted that would identify the rock deformation mechanic throughout the construction process. A detailed monitoring programme composed of precision monitoring targets, inclinometers, and extensometers was established to provide accuracy and redundancy in establishing the movement of the rock and excavation support structure. The results of the programme were used to identify the rock deformation mechanics and further refine the FLAC analysis. To date, monitoring indicates that localized shear band effect is the leading cause of rock movement. The phenomenon appears to be directionally dependent and strongly correlated to excavation extent.

Jan 1, 2008

By Min Sunn Ye, Wei Wang, Huawen Xiao, Kai Yao, Fook Hou Lee, Siang Huat Goh

"Previous research have shown that introducing fibers to cement soil mixture is effective in improving the ductility as well as maintaining the strength of cement-treated soil. A good knowledge of stiffness of the improved soil at small strain is essential for realistic predictions of ground movements that may affect adjacent buildings or underlying infrastructure. This paper presents a triaxial system with local strain measurement developed for studying shear modulus degradation of cement treated clay with fibers. Cylinder specimens (70mm diameter by 140mm height) with 50% cement, 100% water, 0% to 1% polypropylene fibers by mass, and 7 days of curing period were used. A local strain measurement system with floating type miniature submersible LVDT is introduced in this paper. Configuration of the mounts including the pin size, length and distance are presented and discussed. Based on the experimental results, a reasonable configuration of the mounts is recommended for fiber reinforced cement treated clay. Results showed that the proposed local strain measurement system is effective for testing the shear modulus degradation of cement treated clay with fibers under both unconfined and confined condition. Comparisons with results from resonant column and bender element tests served to verify the reliability of the local strain measurements using the proposed method.INTRODUCTIONIn many geotechnical engineering problems, the operational strain domain ranges from 10-3% to 10- 1%. A good knowledge of stiffness at small strains is essential for realistic predictions of the ground movements that may affect adjacent buildings or underlying infrastructure. As such, during the last 3 to 4 decades, the importance of using the small strain stiffness of soils for the design of foundation and underground structures has widely been accepted. Triaxial testing has been widely used to study the stress-strain behavior of soil in the laboratory. However, the stiffness obtained from the conventional triaxial apparatus is usually far smaller than those back-calculated from field measurements. This is mainly attributed to the overestimation of axial strains from the external strain measurements, which usually includes compliance effects of the loading and load measuring system as well as sitting, bedding and alignment errors between sample and system (Baldi et al., 1988). The poor resolution of the external strain measurements is another important contribution. Therefore, conventional procedures are inappropriate for small-strain stiffness evaluation due to low accuracy and resolution."

Jan 1, 1900

By Racquel Nottingham, Marc Mastrantuono, Freddy Lopez

In the digital era that we live in, connectivity and mobility play a decisive role in our daily activities. In this context, insufficient telecommunication infrastructure gives origin to the so called “dead zones” (areas with poor or non-existing cell phone reception), which hinder economic development in small communities and in many rural areas, since they remain invisible to a larger marketplace due to the inadequate cellular coverage. Several countries are working to identify these dead zones and with this information, establish strategies together with mobile providers in order to improve the existing mobile networks by expanding the coverage areas. As a result of the analysis, it is expected that thousands of telecommunication towers for 4G and 5G networks will be erected in the coming years. Telecommunication towers are slender elements that require large shallow foundations to verify primarily the safety against overturning. However in remote areas, it can be advisable to consider alternatives to the conventional shallow foundations, in order to optimize the use of materials (concrete, reinforcement steel, etc.). The following article presents an overview of intervention projects, where telecommunication towers were founded on micropiles. The micropiled foundations allowed to reduce considerably the dimensions of the originally planned shallow foundations. Furthermore, the use of micropiles allows for additional optimization, in combination with pre-fabricated foundations (i.e., precast concrete elements, etc.). This paper will focus mainly on the design and the execution of the micropiled foundation.

Sep 8, 2021

By Stefan Swartling, Rudy Lyon, Donald A. Bruce

"Since their first production application in Sweden in 1995, water-powered, down-thehole hammers (WDTH) have been used throughout the world in many different drilling applications, total lines, over 25 million lineal meters of drill hole. This paper reviews the history and principles of down-the-hole drilling (DTH) in general with both air and water, before focusing on the details of WDTH hammers. A summary of the numerous and considerable advantages of WDTH drilling is provided, with particular emphasis on their superior productivity, smaller deviation, applicability in sensitive/urban conditions, environmental protection and much reduced energy requirements.HISTORICAL PERSPECTIVE ON PRODUCTION DRILLING METHODSAir-flushed drilling with top hammers began in the mining industry in Sweden in 1873, while down-the-hole (DTH) drills, again with air flush (and activation) became operational in 1950. During that same time interval, Simon Ingersoll had patented the first steam-powered, top hammer rock drill to provide higher productivity in blast hole drilling. It is well known that water, as an activating, flushing and cooling medium, has many significant advantages over the use of air. However, it was not until 1973 that top hammer systems (either air or hydraulically activated) for larger rigs were adapted to the use of water flush, typically via “under the head” swivels.The concept of a water-powered, down-the-hammer (WDTH) had been explored prior to G. Drill acquiring the original patent from Atlas Copco in 1988. LKAB, a huge underground mining company owned by the Swedish Government and providing about 90% of the European Union’s iron ore, purchased G. Drill in 1991 and encouraged the commercial development of the WDTH. The first full-scale WDTH production works were carried out for LKAB in 1995, since when over 25 million lineal meters of drilling have been recorded in both underground and surface applications.In 2001, G-Drill was renamed Wassara, which today still holds the worldwide patents for WDTH technology. Regarding North American usage, the first significant application was by Advanced Construction Techniques (ACT) Ltd. during the test grouting program conducted for the U.S. Army Corps of Engineers at McCook Reservoir, Chicago, in 2002. Since then, WDTH has become the tool of choice for specialty drilling and grouting contractors on dams and other major structures throughout the U.S."

Jan 1, 2015

By Moritz Schleeh, Christian Moormann

Temporary working platforms are generally required in order to ensure that heavy construction machinery such as drilling and trench wall units, pile drivers, vehicle and crawler cranes can be set up safely at the site of operation. Considering all possible operating and loading conditions, especially on ground of low shear strength and stiffness, the design and construction of temporary mobile working platforms needs to be considered more as a serious engineering task than as a second order structure of minor relevance. Working platforms reinforced with one or several geosynthetic layers have proven to be especially effective with regard to stability, serviceability and durability but their design requests even more sophisticated approaches. Existing design models are often based on simplified assumptions and do not consider the complex interaction between construction machinery, working platform and subgrade. Non-monotonic loading as well as elastoplastic and time-variant deformation of cohesive subsoil can adversely affect the base layer system and the serviceability and stability of the construction machinery operating on it. In this context, there is a need for improvement of design approaches and their optimisation considering that there are no generally accepted design approaches or technical codes of practice available for the design of temporary working platforms. The present paper deals with the multifaceted and non-trivial interaction effects of working platforms investigated by model tests, field measurements and numerical simulations to develop a design approach that ensures a safe installation and operation of heavy plants on unstable ground.

May 1, 2022

By Les R. Chernauskas

? What is Integrity Testing? ? Cross-Hole Sonic Logging (CSL) ? Single-Hole Sonic Logging (SSL) ? Typical Specifications ? Case Histories ? Observations and Conclusions WHAT IS INTEGRITY TESTING? General Definition ? Process in which the condition or structural makeup of an object can be evaluated with respect to defects such as a reduction in cross section (void or crack) or reduction in material strength (water, slurry, soil mixed with concrete). ? If the defect is severe enough, it can reduce or alter the load carrying ability of the object.

Jan 1, 2001

By Greg Canivan, Bernie Hertlein, Les Chernauskas, Joram Amir, Garland Likins, E. Anna Sellountou, Tim Kovacs, Peter Kandaris

Nondestructive testing of drilled shaft foundations via Crosshole Sonic Logging (CSL) is often performed as part of the quality assurance process to assess the soundness of concrete. The intent of CSL testing is to identify irregularities such as soil intrusion, necking, soft bottom, segregation, voids and other defects that could result in poor structural performance of the foundation. Over time, CSL rating criteria based on first arrival time and relative energy have incorrectly evolved to often be the sole means of determining the acceptability of a shaft. Some of these criteria have found their way into regulatory agency specifications, with acceptance values often differing from agency to agency.The purpose of this document is to review the state of the practice (including experience gained over the past 20 years), propose improved CSL rating criteria and make recommendations for additional assessment, as well as educate the industry on the proper interpretation of CSL test. CSL test results alone should not be the sole means of rejecting or accepting a shaft. A task force of industry exerts was formed to review the existing CSL rating criteria and propose improvements where appropriate. The recommendations presented herein are the consensus of the task force, which believes that they should be incorporated into future criteria, codes and specifications. This paper was produced as a joint effort between the Codes and Standards Committee, the Drilled Shafts Committee and Testing and Evaluation Committee. A task force was authorized under Testing and Evaluation Committee. The task force contributed their expertise in web-based discussions often every two weeks over a period of three years. Interested participants were invited to participate at any time. The document had two rounds of broad industry review, two rounds of DFI Technical Advisory Committee reviews, and a Public Comments process. All comments were considered in producing the final document.

Jan 1, 2019

By Arash Saeidi Rashk Olia, Dunja Perić

The increasing demand for renewable energy has attracted attention to energy geostructures as means of extracting clean geothermal energy from the ground. To further advance the understanding of soilstructure interaction in energy piles analytical solutions considering the self-weight of the pile were derived. These solutions were then incorporated in recently-derived thermomechanical weightless solutions to provide comprehensive analytical solutions for axial displacement, strain and stress in single energy piles. This was accomplished by comparing responses of energy pile under different loading scenarios that reflect presence and absence of the self-weight. Results of mechanics-based analysis revealed that the self-weight of energy piles embedded in stiff soils has no significant contribution to displacement, strain and stress that develop under thermo-mechanical loads. Overall, the significance of the self-weight contribution depends on the magnitude of thermal load as well as the soil-pile interface stiffness. The stiffness of end restraints imposed to the pile head and tip were also found to play an important role in contribution of self-weight in induced thermomechanical stresses in energy piles.

Oct 1, 2022

By I. K. Ozaydin

Analysis of piles groups loaded with large bending moments and both vertical and batter piles can be best performed by matrix analysis. In this paper, a case history about a tall marine control tower is presented. The soil conditions at the site and the results of the computer analysis of the piled foundation are summarized. It is shown that the pile loads are indeed less than the allowable load for a single pile. Pile head loads and moments are used in the analysis of the raft foundation.

Jan 1, 2010

By M. Kitazume, H. Imai

The deep mixing method was developed in Japan and put into practice in the middle of 1970s. Since then, the wet and dry type methods have been applied for various improvement purposes in Japan. One stork of mixing tool produces a column shape of stabilized soil in a ground. By the series of productions, arbitrary shape of improved ground can be constructed by overlapping each columns. It is specified to complete the overlapping within 24 hours in order to ensure the tight connection of the columns. However, it can not be completed within the specific time in some cases due to bad weather or machine trouble, which causes a cold joint in the improved ground. In this study, the influence of the cold joint to the behavior of the block type improved ground is examined by a series of centrifuging model tests and FEM analyses. It is found that the ground behavior is influenced by the position of the cold joint, where the cold joint at the sea side shows a little influence to the behavior but one at the port side causes large decrease in the stability of the improved ground.

Sep 8, 2021

By James S. Graham

Marine design and construction methods are presented on the caisson foundations for the tower piers at the Brooklyn, Ben Franklin, Delaware Memorial 1st, Tappan Zee, Walt Whitman, Throgs Neck, Verrazano Narrows, Delaware Memorial 2nd, and Newport Bridges. All of the bridges are founded on caissons, bearing on bedrock, soil, or piling. Caissons at the Tappan Zee Bridge are partially supported by piling and partially by buoyant forces. General subsurface conditions for each are provided. The purpose of this paper is inform engineers how bridge foundations using caissons were built over major waterways in the Northeastern USA in the past, anticipating a surge of new bridge construction in the near future.

Jan 1, 2005

By Douglas L. Scaggs

Driving piles in under water applications has become more common place over the past twenty years. Where only a water depth reachable with a follower or dewatered cofferdam was the rule in the past, newer technologies developed for the offshore oil and gas industry have made depths of even several thousand feet possible offering new possibilities in foundation design and installation. With the new technology, engineers can now more efficiently design structures by placing foundations optimally thereby reducing weight and cost of the overall structure.

Jan 1, 2013