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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 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 Dawn Shuttle

In trying to find a grout, or some kind of stabilizer that would work in this application, we established some performance criteria. Of those, what I controlled the most was viscosity, then I had a whole list of other criteria. I needed a long, controllable gel time, durability and the ability to set and stabilize the soil. So I looked through a lot of different stabilizers, some really crazy ones and also the typical chemical grouts that are used. The typical chemical grouts were eliminated because of long-term durability concerns, the need for having extended gel times, and several other concerns. I would be happy to discuss that with you further after the talk if you're interested. But, generally it was based on viscosity, gel time, and the need for extended gel time. In terms of the relative density of the sand many other grouts could have been used. But the main issue was trying to develop this way to do low pressure grouting that would not cause invasive disruption of the site. We couldn't go in and grout it, put centers, so most of the other grouts wouldn't work for various reasons. The forty percent relative density samples were prepared by plubiation. That was both during the cyclic testing stage of the research, which happened a few years back, and also during the box model and the laminar box models at RPI. In terms of what criteria were used to determine the success of the grouting, when I initially started this work what I did was take the grouted samples and I subjected them to cyclic triaxial testing. What I did was take a look at the cyclic deformation resistance of different concentrations of grouted colloidal silica treated sand. I looked first at 20% concentration because I wanted something that I knew worked and then I gradually decreased to 15%, 10%, and 5%. What I was most concerned with was that it did not liquefy and that it was able to hold together it and experience some deformation. But most importantly it needed to not liquefy. So, that was the biggest issue in determining the success of the grouting. In terms of the centrifuge modeling it was done by looking at several components: from looking at the pictures of the bending moments, looking at the acceleration records and how the acceleration records were transferred through the soil, looking at the reduction in the lateral displacement and those kinds of issues. So let me show you the difference.

Feb 10, 2003

By M. Hesham El Naggar, Mehdi Heidari

"Equivalent fixed-base cantilever model is a common approach for performance base seismic design of bridge structures supported by extended pile-shaft. In this method, global displacement ductility factor is related to local curvature ductility demand by assuming a concentrated plastic hinge at location of maximum bending moment. Equivalent plastic hinge length is one of the key parameters that should be assumed accurately in kinematic expression of the cantilever model. Although, some expressions have proposed to estimate the length of the in-ground plastic hinge; however, these relations yield differing results. In this paper, a general expression is derived based on the concept of distributed plasticity to predict the plastic region of yielded piles in clay and sand. A length modification factor is defined to relate the equivalent length of plastic hinge to the real plastic zone. Then, results from nonlinear pushover analyses are used to propose an equation for the modification factor as a function of displacement ductility factor.IntroductionDuring severe earthquake events, development of the plastic hinge in pile foundation below ground level is inevitable for bridge structures supported on extended pile-shafts. A common approach for seismic design of the yielding pile-shafts is to replace the pile-soil system by an equivalent fixed-base cantilever assuming the equivalent system has the same global response as that of the pile-shaft (Budek et al. 2000; Chai 2002). In this method, plastic curvature is concentrated at the center of the equivalent plastic hinge below ground surface. Prior knowledge of plastic-hinge length is essential for proper assessment of assess plastic displacement at the top of the pile-shaft. Unfortunately, existing recommendations for estimating plastichinge length are largely incomplete and/or inadequate.During the last two decades, several relationships have proposed for evaluating the equivalent plastic hinge length, Lp, based on experimental and numerical studies. Budek et al. (2000) conducted numerical modeling to calculate the plastic-hinge length of piles embedded in cohesionless soil. They found that the plastichinge length varies linearly with both soil stiffness and aboveground height, e. Chai and Hutchinson (2002) conducted full-scale experimental tests on reinforced concrete piles in sand. They reported that Lp depends primarily on the aboveground height of the pile, neither sensitive to the soil stiffness nor to the value of displacement ductility factor. They stated that the equivalent plastic hinge length is relatively independent of the displacement ductility factor and is not very sensitive to the change in soil density. On the contrary, Goel (2014) and Liu et al. (2016) conducted nonlinear numerical analyses which revealed that Lp changes with the displacement ductility factor and even suggested that using different values of Lp for different seismic design levels is essential for a reliable estimation of the ductility capacity."

Jan 1, 2017

By Mohammad Ali Rowshanzamir, Mehdi Aghayarzadeh

"This article is an effort to improve our understanding of the performance of geogrid retaining structures (GRS) through numerical analyses. The numerical modeling utilized a commercially available finite difference program, FLAC3D. In this context an extensive parametric study has been carried out on two different GRS walls (vertical reinforced block and inclined reinforced block) to investigate the influence of internal design factors such as soil strength properties and reinforcement stiffness on the performance of these walls. The main purposes of the parametric study were to (1) investigate the sensitivity of the modeling results to the input material properties, (2) examine the influence of the internal design factors on the performance of GRS retaining structures, and (3) improve the internal design of GRS walls on the basis of the working stress information obtained from the parametric study. Based on the analyses results, it was revealed that GRS walls with oblique reinforcement and reinforced block (rotated against natural backfill) have much better performance in terms of reduction in the stresses and strains of reinforcing elements as well as decrease in the wall lateral and vertical displacements in comparison with vertical reinforced block (conventional wall). For example, with 12° inclination of the wall reinforced block there was 50% reduction in the backfill settlement. Also increasing the reinforcement stiffness amount from 10MPa to 50MPa decreases the wall face displacement more than 50% in both GRS walls.INTRODUCTIONOver the past few decades, Geosynthetic- Reinforced Soil (GRS), a soil mass reinforced by geosynthetic layers to restrain the soil lateral deformations, has been employed in the construction of many types of earth structures, including retaining walls, embankments, slopes and bridge abutments. In fact GRS structures are typically more flexible (hence more tolerant to differential settlement), more adaptable to low quality backfill, easier to construct, require less over-excavation, and more economical. Nevertheless, there is a need for an accurate design tool that can predict the performance of GRS structures under working stress conditions and can predict their failure loads as well.Many studies have been published on the performance of the soil reinforced walls such as Isabel et al., 1996; Bathurst et al., 2000; Kazimierowicz-Frankowska, 2005; Nernheim and Bathurst, 2008; Chen and Chiu, 2008 Correia et al., 2012; Erlich et al. 2012. Several numerical studies have also been made throgh finite elements and finite difference techniques on reinforced soil retaining walls to analyze the wall deformations (e.g. Hatami et al. 2001& 2006, Liu and Won 2009, and Abdelouhab et al. 2011). A limited laboratory research has been reported indicating of improving effect of tilting face on GRW performance (Chen and Chiu, 2008). However no major numerical study was found on the effects of face or reinforcement tilting."

Jan 1, 2017

By Sylvia S. Eskander, Sherif S. AbdelSalam, Mona B. Anwar

Expanded Polystyrene (EPS) geofoam has long been used in numerous geotechnical applications due to its lightweight and durability. Among these applications is the use of EPS as an alternative fill material to conventional roadway soil embankments. This study investigates the benefits of using EPS roadway embankments to reduce the induced stresses and strains on the underlying peat and soft clay. Firstly, mechanical and interface properties of the EPS were acquired from a companion study that also considered the cyclic loading and creep effects. In order to determine the actual stress-strain distribution within the EPS blocks, a physical prototype was developed in this study with overall dimensions of 1.2 x 1.0 x 0.5 m, with a density of 35 kg/m3. The prototype EPS blocks were subjected to cyclic loading with intensities ranging from 10 to 50 kN. Then, a numerical model was developed to simulate the behavior of EPS roadway embankments. The numerical model outcomes were verified against the prototype measurements. A parametric design study was also conducted to develop a correlation between EPS embankment height and the stress-strain that occur in the underlying strata. Results showed that EPS embankments could reduce stress and settlement in the underlying soil by about 40% and 54%, respectively. EPS APPLICATIONS AND BACKGROUND Expanded Polystyrene (EPS) geofoam blocks have been effectively used during the past several decades in numerous geotechnical applications. EPS static and dynamic properties as well as interface behavior were extensively characterized in various published studies such as that conducted by Horvath, 1994; Stark et al., 2004; Zarnani and Bathurst, 2008; Trandafir et al., 2010; Athanasopoulos et al., 2012; AbdelSalam and Azzam, 2016; and others. However, to be able to use locally produced EPS blocks, its physical and mechanical properties must be thoroughly determined. The lightweight and compressible material of EPS geofoam makes it suitable both as a backfill and for absorbing pressure in both the vertical and horizontal directions. Kim et al. (2010) adopted EPS as an alternative for soil backfill around buried pipes; their model showed a reduction in the vertical stress acting on the pipes by up to 36%. Oshati et al. (2012) presented a case study of a field-instrumented box culvert with EPS blocks on top, which reduced vertical stress by 58%. Meguid et al. (2017) used an EPS inclusion to surround culverts and achieved up to 72% stress reduction, depending on the EPS density and the culvert depth to width ratio. AbdelSalam et al. (2017) used a relatively thin EPS inclusion behind flexible cantilever retaining walls, verifying that the lateral pressure can be significantly reduced by 25%; they also developed a design chart for this application. Moreover, AbdelSalam et al. (2019) investigated the use of EPS as a lightweight alternative for soil backfill above shallow tunnels. It was found that EPS had created a differential movement between the wedge located above the tunnel and the neighboring soils, which accordingly reduced the vertical stress acting on the tunnel by 85%, due to the use of lightweight EPS material and positive soil arching.

Jan 1, 2019

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 David Coleman

This paper presents a case history involving the installation of drilled in piles with rock sockets for the Bicycle and Pedestrian Path project located west of the Henry Hudson Parkway within the Riverside Park between 83rd Street and 91st Street at the Hudson River in New York, NY. The paper specifically addresses access and construction procedures for a marine installation when working in an urban and environmentally sensitive setting.

By Tony Suckling

"As we head toward the United Nations Climate Change Conference in Copenhagen in December, the environment and sustainability will become headline news for a while. Governments are expected to agree to a set of binding targets to reduce carbon emissions probably before 2020, and certainly before 2050. This will, in effect, initiate a low carbon economy in many parts of the world. Sustainability has mainly been rhetoric so far, the exceptions being projects for those looking to the long-term future and not for short-term financial gains.The probabilities and consequences of negative impacts on the environment and on society over the short term and in the long term can be assessed and mitigated, but mitigation often adds cost. Also, we cannot know what technologies will be available, say 1,000 years into the future, which is about 40 generations of our society. It is easier to have a connection with 100 years into the future, which is only about 4 generations. Individuals may have a different sense of sustainability, and place a different value on mitigation, its cost, its importance and its potential impacts.Sustainability means different things to different parties on a construction project. For example, a land developer is likely to have a different view on the design in terms of sustainability than that of the designer. The developer may also likely to be more interested in sustainabiliy if there are tangible economic benefits that might accrue. Achieving sustainability on any project, leads to conflict between competing interests or demands cooperation between the economic and technical sectors involved. The foundations for a building or bridge, by definition, need to interact with the ground whose behaviour cannot be dictated by man. The aims of sustainability are the same as for the building or bridge, both of which are constructed of manmade materials, but it is less clear how they should be achieved. An example is the driven pile that does not produce spoil waste, but is likely to be too noisy to be acceptable in an urban environment. This then begs the question, should the public accept the nuisance of short-term pile driving to achieve a more sustainable foundation? Additionally, the question has to be asked, can the deep foundations industry develop its techniques and products to help make them more acceptable and appropriate more often than is possible now?"

Jan 1, 2009

By Nabil F. Ismael

Load tests were carried out to examine the ultimate bearing capacity of short, large diameter bored piles in connection with the construction of a multistory building on the Arabian Gulf in Kuwait. Testing included 0.45 m, 1.0 m, and 1.2 m piles installed through loose sand into a bearing stratum consisting of very dense cemented sands. All tests were carried out to failure. The base resistance and shaft friction were calculated using the Meyerhof method for a layered soil profile. The method employs the standard penetration test N-values. The results indicate that the piles are end bearing piles with a great portion of the pile capacity due to base resistance. The mobilized skin friction is small. The calculated pile capacities were very close to the measured values with the maximum difference not exceeding 10%.

By Manfred Schoepf

"Construction projects using the most advanced technologies and organizational structures demand intelligent construction machinery. In this process, automation technology plays an increasingly important role. Many components used in the automatic control of machine components are being taken for granted to such an extent that operators are often even unaware of their existence. Innovations in micro-electronics, such as process computers, programmable logic controllers (PLC) or intelligent sensor systems, have by now found their way into construction machinery. Construction machines are indeed becoming ever more intelligent. Key electronic applications in foundation engineering machines can be summarized into the following main categories:- Data acquisition- Online monitoring of the equipment status- Remote data transfer- Satellite-based Navigation System for Positioning and Documentation- Process controlData acquisitionThis includes machine-specific operating data, such as engine speed or operating temperature, operating hours, display of fuel consumption, but also the acquisition of process-specific data, such as pile depth, pile inclination or slurry volume.Monitoring the equipment status onlineAn extremely important aspect is the acquisition of fault data. In conjunction with available remote data transfer systems, malfunctions can now be searched and diagnosed by specialists anywhere in the world to provide assistance to the site personnel.Remote data transfer - “Anywhere, from everywhere”All previously referred to parameters can be stored on appropriate storage media inside the machine. The customer also gets a worldwide, safe access via an internet browser to check the current status of the equipment, anytime, anywhere.All data can be saved on a secured web server for documentation and further analysis. The internet connection of the equipment through a special module (DTR Module) additionally allows the user to operate a local, password-saved WLAN hot spot at the construction site and exchange data between equipment, tablet and internet.The web based system, which is named “WEB-BGM Equipment Management” in the Bauer Group, can do much more than only communicating with one machine."

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 Dale E. Berner

A new navigation dam at Olmsted on the Ohio River will be built "in-the-wet" using a lift-in construction method by the Washington Group/Alberici Joint Venture for the U.S. Army Corps of Engineers, Louisville District. Up to 4,000-ton precast concrete dam shell segments will be prefabricated on the Illinois riverbank and lowered into the river on a marine skidway and cradle. A 4,500-ton capacity catamaran crane barge will lift the precast concrete shells and lifting frames from the cradle, and transport them partially submerged to a piled foundation pre-installed underwater. Tremie concrete will be used to compositely connect the shells, piles and sheet pile cut-off walls. This paper focuses on the pipe-pile foundations for this half-mile long navigation dam, and for the temporary precast yard and marine skidway. The dam foundations are designed to resist large ground motions from the New Madrid Fault Zone, and selected production piles are designed to serve as landing piles to support the shells during the construction process. Specific foundation issues addressed in the paper include: pile load tests; production field testing requirements; controlled fixity 24-inch diameter pipe-pile design including seismic considerations; cut-off wall design; sheet pile cellular fixed weir design; isolation jOint design; and temporary works foundation designs for both the precast yard and the marine skidway, including testing of 42-in diameter pipe piles.

May 11, 2007

By Kiyotaka Ohno, Nobushige Yasuoka, Yosuke Hioki

"The diameter of improved columns adopted by the original DJM Method had been 1000 mm, however, in order to comply with the social need for construction cost reduction, the Expanded Dry Jet Mixing (EX-DJM) Method with maximum column diameter expanded to 1300 mm was developed between 1998 and 2001 and has been widely applied since then. From the first application of EX-DJM in January 2002 for a first construction project, the total volume of improved soil has reached 325,000 m3 in 17 projects up to September 2014. Because of the advantages of the EX-DJM such as reduction of construction costs and periods leading to reduction in the number of improved columns, adoption of this method is expected to increase in the future. This paper describes the advantages of the EX-DJM, its construction results and case examples including those applied to restoration projects after the Great East Japan Earthquake, 2011.1. BACKGROUND OF DEVELOPMENTThe Dry Jet Mixing (DJM) Method is a soil stabilization method in which a powdery or granular binder is pneumatically fed into and mixed with soft soil to induce chemical reactions that stabilize and strengthen the soil. It was developed by government - private collaboration in Japan between 1977 and 1979. Up to March 2014, the total volume of soil improved by DJM method reached 33,500,000 m3. The initial diameter of improved columns of the original DJM Method was 1000 mm. In order to comply with the social need for construction cost reduction, the Expanded Dry Jet Mixing (EX-DJM) Method with maximum column diameter 1300 mm was developed between 1998 and 2001.2. ADVANTAGES OF EX-DJMThe construction equipment for the EX-DJM consists of two major parts, which are DJM machine and binder plant are shown in Fig. 1.The construction machine is of double mixing-shaft type with its column diameter expanded to 1200mm or 1300mm. In association with the increase in the column diameter, the binder feeder has also increased its discharge rate by approximately 1.69 times. Same as the increase rate of the area of original diameter 1000mm to diameter 1300mm are shown in Fig. 4."

Jan 1, 2015

By Leena Korkiala-Tanttu, Ilkka Vähäaho, Juha Forsman, Paavo Lahdenperä, Kalle Rantala, Osmo Korhonen

"District of Arabianranta (Helsinki, Finland) has been founded on an old seabed, which was filled with miscellaneous soil materials. The subsoil consists of very low shear strength clays and organic clays (gyttjas). The soil was moving towards the sea at a rate of 1050 mm/year, because of filling on top of the soft subsoil. In the middle of 1990’s it was decided to build a residential area to Arabianranta, because it is located only 5 km away from the downtown. To inhibit the movement of soil, it was planned to build this 700 m long deep mixed column-wall barrier along the shore of Arabianranta in the years 1997–2005. A lot of instrumentation and inclinometers were analyzed and it was noticed that the column-wall remains at its place and the displacement rate inside the wall has been only 0.44.6 mm/year after construction works. Nevertheless, the displacement of soil at the landward side of the column-wall is still 1.25.1 mm/year. The soil at the seaside of the barrier is also moving towards the sea 12.922.2 mm/year. Another problem might be displacements of soil near the places where the column-wall ends (tails).1. INTRODUCTIONArabianranta district (Helsinki, Finland) has been an industrial, storage and wasteland area for a long time. Developing this area into a residential area was earlier considered too expensive, so it has been constructed during last decade. The organic clay layers (gyttjas), which have weak shear strength and high water content, were covered by various layers of fillings done in different phases. Because of the fillings, the area was not only consolidating, but also moving horizontally 1050 mm/year towards the sea due to the fact that the frictional soil under clay layers slopes towards the sea. A trial deep mixed structure was constructed in 1997 to inhibit the horizontal displacements of soil. The actual construction of the columnwall was completed in 2000-2005 with overlapping deep mixed cement columns on the seaward boundary. The barrier was built so that the horizontal movements would not risk the pile foundations at Arabianranta. The length of the barrier is about 680 m and width varies between 1220 m. There is a great amount of instrumentation near the barrier (inclinometer casings and other measuring devices). All this measuring information has been collected and analysed at 2014 to find out how this deep mixed column-wall has affected the horizontal displacements."

Jan 1, 2015

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 Dan Brown

Renewal and revitalization of transportation presents a challenge in the need for replacement, repair, and improvements of existing bridges, as well as increased construction of transit systems within existing transportation rights of way. Difficulties with conventional deep foundation systems occur because of the limited site access, adjacent structures, the need to maintain traffic, and other constraints on construction activity. Major projects are often performed in a design-build contract environment in which the schedule is aggressive, and where speed and reliability represent major considerations. Foundation designers are confronted with a need to solve problems with a construction-oriented mindset, where typical experience with lowest cost solutions may not reflect the most effective approach. This presentation presents an overview of the challenges that may affect design and construction of deep foundations in this environment and the methods that have successfully been employed on several large transportation projects in the U.S.

Jan 1, 1900

By Joseph A. Sopko

There has been a trend in recent years in performing the initial formation freezing using liquid nitrogen (LIN) and then converting the system to circulating refrigerated brine. While proponents of this method state it decreases freezing time, it can also be considered an alternative to inadequate refrigeration capacity. This method was used on several small projects in the 1980s. Problems such as broken pipes, frozen brine, and unsafe work conditions caused contractors to re-think the method. This paper discusses these problems and also presents work schedules showing no schedule reduction. In fact, this method can lead to longer time as well as significantly higher costs. BACKGROUND Ground freezing as a method to provide groundwater control and temporary earth support for excavations is completed using a relatively simple process: drilling and installing refrigeration pipes around the perimeter of the excavation and introducing a coolant into these pipes. The coolant extracts heat from the ground, converting the pore water to ice and forming a strong, impermeable material. A typical ground freezing system is illustrated in Fig. 1. SYSTEMS There are two basic types of coolant systems: circulating and direct expansion. The circulating coolant system is made of two separate, closed systems. The medium circulating is the secondary coolant. It is cooled at a central refrigeration plant, circulated through the pipes, and warms as it extracts heat from the ground. It then circulates back to the plant where it is cooled. This coolant is chilled in a heat exchanger by the primary refrigeration system where a compressor system is charged with a refrigeration gas. The heat is ultimately extracted from the ground and expelled into the atmosphere by an evaporative condenser. Secondary coolants are usually a brine or glycol chemical while the primary refrigeration gas is anhydrous ammonia or another commercially available gas.

Jan 1, 2019

Caissons hand dug to a depth of about 100 feet were used to underpin three important structures at an industrial site in the State of Utah. The caisson shafts extended through 30 to 40 feet of coarse, granular soils and 25 to 60 feet of sands and clays to bear on a very dense, coarse gravel and cobble stratum near the water table. The shafts were belled to 12 feet square at their bearing elevation. Bearing pressures of 20 ksf were assigned. The shafts were lagged with timber. The use of hand-dug caissons allowed continuous operation of the facility during underpinning. Settlements after underpinning have been minor and well within the estimated magnitudes. Instrumentation was placed in two of the caissons with varying degrees of success.

Jan 1, 2010

By Stephan Fisch, Franz-Werner Gerressen

"The use of cut-off-walls (COW) for the open pit coal mines has been used for decades. They have been used to reduce the negative hydraulic impact to the surrounding area caused by the open pit mining. The pile-guided trench cutting system is a worldwide unique technique, originally developed by the engineers of the mining companies themselves. It guarantees a continuous, joint free, COW during a continuous installation process. At this specific site in Welzow, this technique has been pushed to new limits in order to address the local lake region. Depth capability has been designed to about 430 ft (130m), proven are already depth of about 360 ft (110m) at a constant trench width of 39 inch (1000 mm). This project is approximately. 6.8 miles (11 km) long of COW, scheduled to be completed in 12 years period. About 2.05 miles (3.3km) have been installed, which is equivalent of about 3.5 Million ft² (330,000 m²). The system flushes special clay which forms a filter crust at the inner surface of the trench. Only natural clay resources used, in order to achieve the cut-off effect (colmation effect). The paper explains the installation process of the cut-off-wall as well as the equipment systems developed specifically for this project. After a successful start of the first phase of the project, the next step in the advancement of the equipment is already underway to enable the installation of greater depth to approximately 490 ft (150 m +) and beyond. The next generation equipment system is scheduled to start operation around 2018 INTRODUCTIONThis Serbian saying “Bóh je stworil Lužicu a cert je zaryl brunicu – God created Lusatia and the devil buried brown coal underneath it.” captures local communities’ ambivalence towards lignite.Lusatia is an almost entirely flat stretch of land between the Elbe and Neiße rivers dominated by glacial sands. On the surface, the heathland and woodland is hardly noteworthy. However, three large lignite mining regions, two in Brandenburg and one in Saxony, in the east part of Germany, divert the attention to underground level, down to depths of up to 120 meters. Here, seams crisscross the earth like ribbons. They were formed in the Tertiary around 17 million years ago.The mining of the lignite started almost 200 years ago. To enable open pit mining, a suitable dewatering system was required. At first, wells and drainage system were used. With the increasing demand to go deeper to enable full use of the existing resources with greater mining depth, a decision taken back in the 60th of the last century, the amount of water which had to be pumped increased dramatically. In peak times, approx. 1.57 Billion cubic yards per year (1.2 Billion m³/year) had to be pumped. This led to a lowering of the groundwater level for up to 230 ft (70 m), impacting the regional lake landscape. In order to reduce the influence on the water balance, and bring the water level back to pre1970th, a first development took place to implement the use of specific COW system to depth of about 147 ft (45m)."

Jan 1, 2017