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By Saba Mohan

For the three full-scale pile installations, two different high-energy hydraulic hammers were selected for the installation. However, these hammers may not have sufficient energy to drive these large diameter piles at their ultimate capacity following long-term set-up. Nevertheless, these hammers were selected because, soil plug behavior, the generation of excess pore pressures and remolding of soil during driving were expected to reduce the shaft and end bearing resistance, and therefore reduce the energy required to drive these piles to design penetration. Data collected during continuous installation driving and after a series of re-strikes at different set-up times ranging from 1 to 33 days were used as input data for CAPWAP analyses. These results were used to estimate the soil resistance along the pile length and at the toe of the pile, and the soil pile set-up behavior. Validity of the procedures used to predict the soil resistance to driving and predicted blow counts were verified with the field observed blow counts and the energy that was delivered to the pile. Based on combined CAPWAP analyses, the soil pile set-up with time was predicted.

Jan 1, 2002

By Franz-Werner Gerressen, Manfred Schoepf

"Diaphragm walls are known as underground structural elements commonly used as retention systems for excavation pits and shafts and permanent foundation walls or elements. It can be anticipated that, with the increasing trend of utilizing more and more underground space to accommodate environmental considerations and urban/suburban development, there will be an increasing requirement for diaphragm walling in even more complex conditions. Complex and/or challenging conditions in terms of ground conditions have a major impact in regards of choosing the right tools for excavation purpose. Complex conditions in terms of space limitations, especially for inner city job sites, require specifically adapted solutions for slurry, spoil, reinforcement and concrete handling and the related logistic to ensure smooth production. Furthermore, one focus will be given to the QA/QC topics of the production process. Real time installation control, data transfer and reporting systems become more and more important ensuring the five dimensions of a jobsite. Therefore, the paper will describe the construction method and the sequence of activities required for the construction of diaphragm wall systems with the focus on the cutter technology. It will describe also the main equipment which will be needed to execute these works under the various conditions INTRODUCTION Diaphragm walls are known as underground structural elements commonly used as retention systems for excavation pits and shafts and permanent foundation walls or elements. It can be anticipated that, with the increasing trend of utilizing more and more underground space to accommodate environmental considerations and urban/suburban development, there will be an increasing requirement for diaphragm wall usage in even more difficult conditions. Of course diaphragm wall can also be used as deep groundwater barriers (Cut-Off-Walls). This market has shown that the demand for these types of walls is reaching more and more difficult soil conditions or required depths which are surpassing the current standard. The trench cutter is the most important tool for performing this work. The trench cutter itself is a reverse circulation excavation tool. It consists of a heavy steel frame with two drive gears attached to its bottom end, which rotates in opposite direction around horizontal axis. Cutter wheels are mounted onto the drive gears. As they rotate, the soil beneath the cutter is continuously being broken up, removed, mixed with the bentonite slurry in the trench and moved towards the opening of the pump suction box. The slurry loaded with soil and rock particles is pumped by a centrifugal pump which is located right above the cutter wheels, up through a hose system up to a desanding plant where the slurry is cleaned and returned into the trench."

Jan 1, 2015

By Kam Ng

For bridges or buildings that may be subjected to large vertical and lateral loads, drilled shafts offer an economic foundation solution. While the current drilled shaft design practice is considered adequate, introducing a performance-based approach to designing the drilled shafts will make their design more cost-effective and produce more dependable response. This concept was examined using analysis of 41 drilled shaft load test data from several states. This process identified the challenge with the lack of information from the Osterberg (O-cell) load test method to characterize the full top load-displacement response. When a typical single O-cell is utilized in a drilled shaft test, depending on the location of the O-cell and the geomaterials present along and beneath the shaft, the load test result typically quantifies either the side resistance or end bearing reaching the ultimate load-displacement curve but not both components. This limitation hinders the determination of a suitable shaft resistance as a function of a target top displacement. To overcome this challenge, an improved procedure is proposed for establishing the full load-displacement curve based on data gathered from one O-cell. The method will be presented in the paper for three different cases (i.e., side resistance reaches the ultimate during the test, end bearing reaches the ultimate during the test, and neither components reach the ultimate values). Because it allows the characterization of the full load-displacement curve, the proposed procedure will allow performance-based design of drilled shafts with due consideration to settlement while satisfying the Load and Resistance Factor Design.

Jan 1, 2013

By Lin Li

A reliability based analysis method for a drilled shaft stabilized slope system is presented in this paper. In the past effort, a deterministic method using the limiting equilibrium method of slices for determining the global factor of safety of a slope reinforced by a row of drilled shafts was developed using the soil arching concept. The drilled shaft stabilization mechanisms for the slope were treated as the drilled shaft induced soil arching, which reduces the driving forces on the down slope side of the drilled shaft. The effect of drilled shafts induced soil arching on the reduction of the driving stresses in the limiting equilibrium slope stability analysis was quantified by the load transfer factor through extensive finite element simulation studies. A semi-empirical equation was also developed for expressing the load transfer factor as a function of the soil properties, including strength parameters and unit weight as well as the slope geometry and soil profile, the location and spacing of the drilled shaft, and the dimension of the drilled shaft. However, due to the inherent uncertainties of the soil properties and the model error of the semi-empirical load transfer equation, a modification of the deterministic method into a probabilistic method is developed in this paper. The Monte Carlo statistical method is used to generate random variables for the soil strength parameters based on the prescribed probability characteristics, including mean, COV, and the probability distribution function. In addition, the modeling error of the load transfer factor is also treated as a random variable in the Monte Carlo simulation method, in which the mean, COV, and probability distribution function for the bias of the semi-empirical equation are used. The developed theories were coded into a computer program for analyzing complex slope geometry and slope profile conditions. Two examples are shown in the paper to illustrate the analysis results of the developed probability approach for determining the reliability of a drilled shaft stabilized slope system.

Jan 1, 2017

By Lin Li

A reliability based analysis method for a drilled shaft stabilized slope system is presented in this paper. In the past effort, a deterministic method using the limiting equilibrium method of slices for determining the global factor of safety of a slope reinforced by a row of drilled shafts was developed using the soil arching concept. The drilled shaft stabilization mechanisms for the slope were treated as the drilled shaft induced soil arching, which reduces the driving forces on the down slope side of the drilled shaft. The effect of drilled shafts induced soil arching on the reduction of the driving stresses in the limiting equilibrium slope stability analysis was quantified by the load transfer factor through extensive finite element simulation studies. A semi-empirical equation was also developed for expressing the load transfer factor as a function of the soil properties, including strength parameters and unit weight as well as the slope geometry and soil profile, the location and spacing of the drilled shaft, and the dimension of the drilled shaft. However, due to the inherent uncertainties of the soil properties and the model error of the semi-empirical load transfer equation, a modification of the deterministic method into a probabilistic method is developed in this paper. The Monte Carlo statistical method is used to generate random variables for the soil strength parameters based on the prescribed probability characteristics, including mean, COV, and the probability distribution function. In addition, the modeling error of the load transfer factor is also treated as a random variable in the Monte Carlo simulation method, in which the mean, COV, and probability distribution function for the bias of the semi-empirical equation are used. The developed theories were coded into a computer program for analyzing complex slope geometry and slope profile conditions. Two examples are shown in the paper to illustrate the analysis results of the developed probability approach for determining the reliability of a drilled shaft stabilized slope system.

By V. Tang

In this paper, Chinese economic situation are estimated and prospective developments predicted to assist those US firms who have been trying to do business in China, or are considering to pursue the China market.

Jan 1, 2010

By Bernard H. Hertlein

The introduction of LRFD methods for structural design has been a gradual process by AASHTO, ACI, AISC, ASCE, and the FHWA, which has largely been ignored by the deep foundations industry. In 2007, however, the industry has been obliged to embrace LRFD for any deep foundations on projects involving federal funds. The authors are concerned that the risks caused by the need for, and the difficulty of providing, reliable quality assurance, will result in unnecessarily high safety factors that will defeat part of the purpose of LRFD. A primary attraction of LRFD for owners and engineers alike is that it promises more efficient design, and therefore cost reductions. Unfortunately, a key element of LRFD philosophy is often overlooked - that the applied safety factors can be rationally reduced, often allowing less material to be used, thus saving costs, but only if all the risk factors involved are identified and closely controlled. This means that both the quality of the materials and the quality of the construction work must be adequately monitored, and held to an acceptable standard. In the case of deep foundations, the soil in which the foundation is constructed is also a critical component that must be taken into account in the assessment of risk factors.

Jan 1, 2007

By Naim Noori Samie

Lateral force rsistance of piles is analytically investigated by dividing the pile length to 3 segments. The first segment (Zone I) models the load eccentricity with respect to the soil and the pile-deck connection, using a third degree differential equation representing the shear variation along the pile. The soil is assumed to be uniform, homogeneous with an elastic-perfectly plastic behavior. The Top soil layer (Zone II) is assumed to be stressed beyond the elastic limit. A simple 4th degree differential equation represents this zone. The soil resistance is assumed to vary linearly with depth (or surcharge). The pile deformation and soil behavior determines the plastic zone length. In zone III the soil is assumed to behave elastically, hence its resistance is proportional to its deformation. A linear 4th degree differential equation is employed in this zone. The compatibility conditions are satisfied on each boundary. Maximum allowable moment and shear are investigated throughout the pile as the basic limiting criteria on lateral force capacity. In this paper the soil coefficients are taken from a proposal by ref(3), and the results are compared with the soil response as determined by the P-Y method as recommended by ref(2).

Jan 1, 1996

By Eric Rehwoldt, Walt Rabe, Jesús Gómez, Tim Myers

"An expansion plan for Washington Dulles International Airport is currently underway to prepare for growth at this northern Virginia facility in the future. While Dulles currently serves more than 20 million passengers a year, when the Master Plan for the Airport is fulfilled, it will be capable of handling approximately 55 million passengers a year. The current Capital Construction Program underway at Dulles will take the Airport one step closer to its full potential.As planned, work includes a new Airport Traffic Control Tower, expansion to existing concourses, a fourth runway, additional parking, and other improvements. One of the most interesting features of this project is the construction of a two-track passenger train system (Automated People Mover, or APM) linking the main terminal and concourses, which will largely replace the Mobile Lounge transportation system, thus greatly reducing surface traffic. Construction of the APM system involves deep excavations along the tunnels and at the transfer stations. This poses special challenges because the settlement-sensitive terminal, original Airport Traffic Control Tower, and concourse buildings, as well as other facilities, exist near the proposed below-ground stations. The site is also underlain by a tight grid of underground utilities that include jet fuel, gas and central communication lines, in addition to more mundane electric, sewer and water mains.One of the most interesting features of this project was the extensive and skillful utilization of micropiles for support of existing structures adjacent to the excavations. Without the use of micropiles, the cost and difficulty of the excavations would likely have been much more. Several important lessons were learned about the use of micropiles, which advance that technology.Throughout the project site, bedrock was generally encountered at 25-ft depths or more. The rock consists of micaceous and highly calcareous siltstone rock. This rock is typical of the sedimentary component of the Culpeper Basin, a Triassic Age geologic feature extending from south central Virginia to western Maryland. The siltstone beds dip gently to the west at about 10 to 20 degrees. Joint planes typically dip 60 degrees to vertical. The rock underlies a sequence of fill materials and residual soils of varying thickness."

Jan 1, 2009

By Jeff Starchuck, Harald Kullmann

"In 2005, an inspection showed that the Deception Bay Wharf in the Canadian Arctic was at the end of its service life. Although Deception Bay is closed with landfast ice up to 5 ft thick, shipping operations continue year-round, with additional voyages in the summer open-water season to supplement mine supplies. The rehabilitation scheme that allowed minimal interruptions to shipping involved concrete caissons cast on barges and an ingenious placing system.WorleyParsons Westmar of Vancouver, B.C., performed the inspection under contract to the owner, Xstrata Nickel, Montreal, Quebec. The wharf, on the coast of the Nunavik region of Quebec, was originally constructed in 1971 for an asbestos mine, and is now used to support Xstrata’s Raglan nickel mine, importing fuel for p o w e r g e n e r a t i o n a n d general mine supplies, and exporting nickel concentrate to smelters in the south. Emergency repairs were essential to allow operations to continue at the site, while the parties considered permanent rehabilitation options and secured funding. The repairs were done in the openwater seasons, and included reinforcing the failed interlocks above water level with steel patch plates and injection grouting of the cell fill below the port crane in 2005. In 2006, workers installed a circumferential belting system below water level.Westmar held critical planning sessions with the mine operation personnel to find ways to stretch the limits of the mine supplies and nickel storage facilities. In the end, the parties agreed to shut down construction activities four times during the ice-free season to allow access to the dock site.Westmar developed a plan that allowed mine operations to continue during construction, and Xstrata approved the plan and budget in September 2006, for execution in 2007. Rapid construction was essential. To accommodate the short construction season and maintain minimum levels of service for the mine, the work was radically different from conventional Arctic deep-sea port construction. Like the original Deception Bay Wharf, construction practice was to use steel sheet pile circular cells with the consequential heavy support services for the labour force. Construction duration was typically two seasons. The plan for Deception Bay was executable in one season based on a concrete caisson structure. Only a modest amount of schedule float was needed."

Jan 1, 2009

By Ahmed H. Bukhary, Naser A. Al-Shayea

The objective is to assess the overconservatism in the parameters used for designing offshore piles. Methodology includes analysis of shaft friction data obtained from more than five different locations in the Arabian Gulf, consisting of 40 piles to depths up to 86 m. Reports were collected for both the dynamic pile monitoring system (DMS) and their corresponding geotechnical reports based on the American Petroleum Institute (API). The values of shaft capacity for the sand layers were analysed by comparing those based on API to the corresponding DMS values. Results of the comparison of the data from these reports showed that the pile design parameters obtained using API guidelines is generally smaller than that measured by DMS. The difference is presented in terms of an overconservative factor (OCF) which is adjusted based on statistical nonparametric test performed on the two data sets. The adjusted OCF were found to be 1.79 and 2.00 for carbonate sand at (loose to medium dense) and (dense to very dense) conditions, respectively. The corresponding values for silica sand were only 1.2 and 1.06. In conclusion, based on the evaluation conducted for data from these reports, the API shaft friction is overconservative for carbonate sand. The API shaft friction for piles in sand can be increased by multiplying it by the adjusted OCF.

By Craig M. Shillaber

On any given day, a simple check of the news will turn up stories related to sustainability, resiliency, climate, or human or natural disaster. In recent years, the winter power grid failure in Texas, the Surfside Condo collapse, unsafe drinking water in Flint, Michi- gan, the Oroville Dam spillway failure, wildfires and flooding (to name a few) have appeared in the U.S. news cycle. As a result, young people are aware of the problems and challenges facing the nation and the world and want to be part of creating sustainable solutions for society. Many choose to major in civil engineering because of a desire to make a difference, address climate change, and develop sustainable and resilient infrastructure for the future. Sustainability is at the core of modern civil engineering practice. In its Policy Statement 418, the American Society of Civil Engineers (ASCE) explains sustainability is a set of conditions where human society can indefinitely keep and enhance quality of life without deteriorating economic, environmental and social resources. Sustainability is an integral part of the technical outcomes identified in the ASCE Body of Knowledge and features prominently in the ethical responsi- bilities of engineers based on the latest version of the ASCE Code of Ethics. Thus, to prepare graduates for successful and ethical engineering practice, civil engineering programs must provide instruction in how to account for social, environmental and economic con- straints in design. Since the deep foundations industry is integral to the broader civil engineering and construc- tion fields and is responsible for supporting critical infrastructure on which human society depends, sustainability should be a key con- sideration in foundations projects. Given the importance of sustainability within civil, geotechnical and foundation engineering, it is worthwhile for the deep foundations industry to consider where and how engineers are trained in sustainability topics through higher education at the undergraduate and graduate level, and what is driving sustainability content in civil and geotechnical engineering curricula.

Nov 1, 2022

By Andrew Baxter

The Crystal Bridges Museum of American Art in Bentonville, Arkansas is a beautiful glass and concrete structure cut into a valley that mingles with water ponds spanned by multiple bridges with suspended roofs. Or, at least it will be when completed in 2009. At Crystal Bridges, most of the proposed buildings involve cuts up to 50 ft high to be retained by the building structures. This requires the construction of retaining walls adequately founded to support lateral loads of up to 70 kip/ft. To add to this difficulty, the site is within a karst region with all the variability and irregularities associated with solutioning and erosion of the parent rock in this environment. The irregular rock profile made it virtually impossible to conceive a predictable arrangement of shallow footings and shear keys for the retaining walls. The existence of layers of soft soils within a hard rock formation made a caisson foundation impractical. The authors developed an innovative solution based on micropiles, which proved to be invaluable from a cost and schedule point of view. In areas where rock was shallow, micropiles were used as ?shear pins? to transfer the horizontal loads to the rock. In areas with significant overburden, a system of vertical and battered micropiles was devised to carry vertical and horizontal loads from the retaining walls. This paper presents a detailed description of the design and installation of the micropiles used as shear pins, and includes the results of lateral load tests performed on full-scale models of the grade beams on shear pins. The work performed shows that micropiles in rock can be effectively utilized for support of significant lateral loads provided that an adequate arrangement of suitably sized micropiles is provided, and that micropiles used as shear pins may develop significant tensile stresses when loaded laterally.

Jan 1, 2008

By Fabio Santillan, Michael F. Zoccola

"Wolf Creek Dam and Lake Cum berland in Russell County Kentucky is operated by the United States Army Corps of Engineers (USAGE) Nashville District It is a combination 3,940 ft long (1,200 m) non-zoned clay embankment, a maximum of 215 ft (65.5 m) above top of rock and 1,796 ft long (547 m) concrete gravity section. Built in the 1940s, the limestone beneath the embankment is characterized by an extensive interconnected network of solution feature; varying from fist size to largecaves.In 2005, studies conducted by the Nashville Distrect concluded that a new seepage cut-off wall was needed as the existing cut-off wall, installed in the 1970s, did not go deep enough and did not extend laterally far enough to intercept all major karst features The dam was classified as a ""Dam Safety Action Classification I (DSAC 1) – Urgent and Compelling,"" the highest risk under USAGE risk category rankings. Also in 2005, under a USAGE risk screening program of its entire dam portfolio, Wolf Creek was classified as a Dam Safety Action Classification 1-Urgent and Compelling, which put it in the highest category. In 2007, an Independent External Peer Review from outside USAGE, concluded there was compelling evidence that a piping failure mode had re-initiated and was in an ""advanced continuation"" stage of development.Impounding approximately 6 million acre-ft (7.4x102m3) of water at flood storage, Lake Cumberland is the largest reservoir east of the Mississippi River and ninth largest in the United States. Catastrophic failure would result in widespread flooding, Ices of life and economic losses in billions of dollars.In 2008, the Nashville District partnered with a joint venture between finns Treviicos and Soletanche (ISM through a ""Best Value"" contract to construct a new seepage barrier wall. This acquisition method was used in lieu of a low bid contract due to complexity of the work and dam safety concerns. It took advantage of the experience and innovation of contractors by soliciting technical proposals that were evaluated independent of cost. Those proposals deemed technically qualified and responsive then underwent a trade-off analysis between ccst and technical approach and a selection was made of the one deemed to give the best combination."

Jan 1, 2013

By Marcus Daubner

This paper explains how BAUER Spezialtiefbau GmbH uses digital methods on projects - starting from work preparation to completion of works. More precisely, the advantages of BIM-based planning during work preparation and the automated and structured data management - both machine production data and the manually recorded quality-relevant reports - during execution phase are displayed. In this context, the benefit of the digital twin to optimize processes, to reduce defect costs, for a more effective reporting sys-tem, and the further usage of as-built information in the BIM or GIS process is described.

Sep 1, 2022

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 Brian Koch

Michels installed 242 drilled shafts to support the piers for a new basket-handle, true-arch twin bridge across the Mississippi River from Moline, IL to Bettendorf, IA. The installation of the drilled shafts was completed with the simultaneous use of two Liebherr LB36 and one IMT 300 drill rigs. Utilizing barges, 233 drilled shafts were installed in the river. Michels crews also installed 7-ft to 10-ft permanent steel casing into the bedrock, and drilled to depths of 60 feet for each shaft. Despite working in strong currents, freezing temperatures and on rocking barges, Michels crews placed the shafts within 3 inches of plan position. Since the drilled shafts are the key piece in supporting the bridge structure, Michels provided cross-hole sonic logging to verify the integrity and strength of the concrete within the shafts and to add another level of quality control for the owner/customer. Extensive planning took place each day to ensure that tugboats, the linchpin of the project, were being efficiently utilized to shift the barges and materials daily. On any given day, Michels transported five concrete trucks by barge from shore to shaft sites to pour between 40 and 240 cubic yards of concrete. The Michels environmental team was diligent with preparing, discussing and implementing a water treatment plan that was accepted by all state and federal agencies and adhered to strict environmental regulations. Grain hopper barges were rented to control and treat the water that was used in the drilling operations. Another challenge crews ran into was the discovery of caverns when drilling into some parts of the bedrock. Michels worked with the engineer to develop a plan to construct the drilled shafts that encountered the caverns.

Jan 1, 2019

By Jim Henry

I would say mainly the cost. I showed only 3 cases. One of them was the one that Allen just described and there were two other cases. In those cases it was fairly easy to develop a solution using limited mobility grout to treat the soft soils suitable for the limited bearing pressures required by the structures. LMG readily provided a fairly reliable system for the foundation support at a reasonable cost.

Feb 10, 2003

By Sherif Elfass, Gary Norris

Bi-directional load testing of drilled shafts has been widely adopted as a means to evaluate their load carrying capacity. However, in order to reach failure, most of these tests are carried out on sacrificial shafts using expensive sacrificial elements such as hydraulic jacks. A proposed low-cost bi-directional testing technique is discussed. It mechanically loads the end bearing soil below a drilled shaft, against its side shear resistance. The technique was originally established as an alternative to post-grouting to reliably account for the forfeited end bearing resistance. However, since it loads the shaft in a manner similar to conventional bi-directional tests, it can be used to not only load test sacrificial shafts, but production shafts as well. Furthermore, unlike conventional bi-directional load tests, the load is applied through surface jacks. These jacks, along with other load test components, are movable and can be reused to load test all the shafts of the project thus presenting an economic benefit. The concept of this technique has received favorable feedback from a few consulted departments of transportation, and while promising, has not been field tested to date. A U.S. patent was issued for the tip loading module and the loading technique described.

Sep 8, 2021

By Yahia M. Al-Smadi

Effect of lateral loading against existing sheet pile wall and distribution of gravity loading due to various number of construction loading scenarios were studied. The objective of this effort was to determine the loading case that permits the contractor to utilize a 400 ton crane at the specified location with the existing limitation imposed on site. Staged analysis was determined as the methodology that will more accurately predict the exiting and additional stress due to the impose crane loading. A reliable and robust analysis (ANSYS) software was used to complete both 2D and 3D finite element model and analysis. Analysis model parameters such as material properties, non-linear behavior of the soil, and meshing are presented and discussed. At the conclusion specific range of crane operation and pick weights operating on existing concrete mat supported on top of an existing tunnel was reviewed and deemed acceptable.

Jan 1, 2010