Search Documents

By Tracy Brettmann

The Highway 146 Bridge Expansion Project across the Clear Creek Channel in Houston, Texas was designed on driven precast concrete piles. However, during construction, the piles along one side of the bridge along the main channel encountered obstructions and couldn’t be installed. These obstructions turned out to be the remnants of a previous bridge foundation at this location, which was unknown to the designers since that bridge had been demolished 40 years ago. Those old foundations were massive 20 ft by 40 ft (6 m by 12 m) pile caps 11 ft (3.3 m) thick supported on precast concrete piles 37 to 55 ft (11 to 17 m) long. The foundation re-design for these locations involved installing a single 78 inch (2 m) diameter drilled shaft up to 125 ft (38 m) long to replace the originally planned driven pile supported pile cap. The drilled shafts would need to be installed within very tight tolerances since they were supporting a single bridge column directly above it. In addition to drilling through the obstructions, this work would need to be completed from barges in 30 ft (9 m) of water capable of dealing with both the current and tides affecting this area. The shafts were installed using a multi-step process. The first step involved coring a larger diameter 100 inch (2.5 m) hole through the reinforced concrete pile cap and removing the concrete inside. This was followed by the installation of a 72 ft (22 m) long permanent casing to and removing the soil and existing precast piles inside. Finally, the drilled shaft excavations were advanced to the completion depths (uncased) using bentonite slurry as the support fluid.

May 1, 2022

By Charles Winter

The Ohio Department of Transpor- tation's (ODOT's) $228 million 1-480 Valley View Bridge project was needed to keep traffic flowing on one of the state's busiest freeway segments. Deterioration from age and steady high- traffic volumes necessitated the replacement of the existing decks of the I-480 east- and west-bound bridges over the Cuyahoga River Valley in suburban Cleveland. To facilitate this work without creating tremendous backups and traffic delays due to long-term lane closures, the project included design and construction of a new four-lane bridge in the median gap between the existing 1-480 bridges. Now complete, the new center bridge allows for all four lanes of I-480 to be maintained in each direction while deck replacement and other repairs are made to the existing bridges, while also providing increased capacity after project completion. ODOT awarded the project to the Walsh Design-Build Team (DBT) in late 2017. This article describes how the Walsh DBT, with Jacobs Engineering as the DBT lead design firm, incor- porated an innovative approach to the design and construction of the driven pile foundations for the new I-480 center bridge. I-480 crosses approximately 200 ft (60.9 m) above the Cuyahoga River Valley. With an overall length of 4,150 ft (1,265 m) and spans ranging from 180 to 300 ft (54.8 to 91.4 m), the design and construction of the foundations for the new center bridge were critical to the success of the project. Due to their overall height and span lengths, the foundation loads for a typical pier consisted of a factored vertical load of 22,000 kips, (100 MN) plus significant overturning forces due to horizontal loads and thermal effects.

May 1, 2022

By Hector Simchas

"1. BENTONITE: THE CRUCIAL CONSTITUENT OF SLURRYSuspensions of bentonite and water are used in a variety of applications in underground engineering. For the construction of underground elements like slurry walls or piles, bentonite slurries offer support to the excavation of loose soils and counter pressure against hydrostatic pressure of ground water, especially where soil permeability is high. In addition, for the construction of tunnels by the slurry-shield method or when hydromills are used for excavation, bentonite suspensions transfer the loosened soil to the surface. In applications like pipe jacking and microtunneling, or where high revolution drilling is required, bentonite also provides lubrication and cooling.To fulfill these functions, the properties of a bentonite slurry need to remain stable, or at least predictable, during the course of construction. Unfortunately, when a suspension mixes with earth, ground water and/or impurities, its properties may be compromised resulting to reduced performance, which would in turn lead to increased construction costs and the risk of the excavation collapsing. Our experience in the lab and onsite is presented herewith.2. MOST USUAL FACTORS OF PERFORMANCE FAILUREWater and soil quality are important factors defining the behavior of suspensions. In an extensive program of measurements in our technical laboratory, the effect of frequently encountered harmful substances on bentonite suspensions has been examined and the results are summarised in Table 1.Some tests show that the conductivity of water has a direct relationship with Marsh Viscosity. For example, we have seen that if the quantity of bentonite required to achieve a 40s Marsh Time ranges between 50-52 kg/m3 at water conductivity below 100 µS/cm; when conductivity is increased to 1,400 µS/cm, we need 65-68 kg/m3 in order to achieve the same property."

Jan 1, 2015

By Danny Winters, Wesley Schmutzler, Christopher Lewis, Matteo Bertoni

"SR 83/US 331 is a primary North/South roadway in Walton County that is a crucial link for tourism and commerce between the Walton County beaches and the heavily traveled I-10 corridor in the panhandle of Florida. The facility also serves as the primary hurricane evacuation route from southern Walton County. This 3.4 mile project involves expanding the current two-lane crossing of Choctawhatchee Bay to a fourlane facility to increase capacity and dramatically improve mobility within the corridor. One of the major goals of the project is to perform ground stabilization using Deep and Shallow Soil Mixing (DMM & SMM) along existing causeways. Ground stabilization is required due to the existence of moderately deep very loose soils that have settled considerably over the years. As a result, the Florida Department of Transportation (FDOT) incurred significant maintenance expenses and was unable to maintain an acceptable ride quality. FDOT considered soil mixing as one option to control this settlement. Quality Control for soil mixing relies heavily on the monitoring system used to control mixing parameters. This paper will examine in detail, the reporting of the Drilling Mate System (DMS) used to ensure the quality of each soil mixed element.INTRODUCTIONThe Florida Department of Transportation (FDOT) issued a Design-Build Maximum Price Request for Proposal (RFP) for the Choctawhatchee Bay Bridge expansion. The design-build (D/B) team of Skanska/Parsons Brinckerhoff was awarded the contract. The D/B team, in order to meet the unique deep ground improvement challenges of the Choctawhatchee Bay Bridge Project, selected Foundation & Geotechnical Engineering (FGE) as the engineer to design the ground improvement and TREVIICOS South (TIS) to execute the works.The FDOT in their RFP states that “either bridge or utilize a deep ground improvement method to stabilize the three segments of the existing earthen causeway” and “one possible method of deep ground improvement which is considered viable is deep soil mixing”. FGE developed a proposal to provide a unique rigid transfer platform to effectively stabilize the existing causeways. This platform (Fig. 1) consists of an upper 10 ft thick stabilized soil layer which transfers axial load to a series of deep columns. This robust system guarantees superior durability, ride quality and pavement condition and will exceed all required design and performance criteria including, “Less than 2 inches of settlement within a 1,000-foot section”."

Jan 1, 2017

By N. Schmitz

This paper explains how new digital solutions improve reverse circulation drilling operations. Upgrading field-proven reverse circulation drilling (RCD) rigs with new digital technologies enables semiautomated drilling, with upgrade options for fully automated & remote drilling. Key elements of the improvements are electrically controlled valve systems, process instrumentations, a state of the art machine controller and drilling operation via a touch control panel. Automation of core processes, such as adding drill pipes, reduces set-up times, increases machine uptime for drilling and as a result efficiency. While drilling, sensors provide continuous feedback, which is used to automatically adjust e.g. the weight on bit to the optimum; resulting in an increased rate of penetration and less wear and tear. While in the past hydraulic power packs (HPU) have typically been operated at a constant high-performance level with related high fuel consumption, a new interface between the machine controller and the power unit regulates the HPU performance exactly according to the actual drilling operation needs. This leads to significant fuel consumption reduction. The safety benefits of the digital improvements are the ability to remotely operate the rig in challenging site conditions via a mobile operator panel.

Sep 8, 2021

By Mohamed A. Eliwah

This paper deals with the determination of hydraulic conductivity of the coastal coralline limestone aquifer of Jeddah, Saudi Arabia. This coastal area has witnessed urban development and establishment of towers which requires deep foundations, excavation and dewatering of huge quantities of unconfined groundwater. It is occupied with successive layers of soft detrital and consolidated massive cavernous coralline limestone of the Quaternary age. These layers are encountered at a depth of 1.5m and extend for more than 100m. Hydraulic conductivity values were obtained by analyzing the pumping tests data under steady and transient state conditions. Hydraulic conductivity values help in selecting the proper and safe dewatering system, as well as determination of discharge rates and quantities of groundwater to be withdrawn. Test results obtained from two surveyed sites showed that the values of hydraulic conductivity are greatly variable. It ranges between 118.1 and 1559.6 m/day at the first site, whereas at the second one it ranges between 94.6 and 350 m/day. These high values are attributed to the cavernous nature of the water-bearing formation. Jeddah city could be divided into three different dewatering zones extending from north to south parallel to the coast line. Well point dewatering system could be applied in the first zone while ditches and sumps are the most suitable dewatering method in the second and third zones. Dewatering using deep wells in such highly permeable formation will require withdrawal of huge quantities of water which will be accompanied by washing out fine sediment filling the cavities in the surrounding areas. This will badly affect the nearby buildings through settlement, crakes and other structural damages. Therefore, construction of grouting plug/blanket with thickness of 3.0 m at a depth of 20.0 m is recommended. This depth will be enough to support the plug against the hydrostatic pressure. Moreover, it is highly recommended to transfer the site into closed box, by using diaphragm walls or secant bored piles.

By Andhra Pradesh, Nagarajkumar B. V

As a part of Mumbai City Mega Drinking Water Project at Amar Mahal Tunnel-1 Ghatkopar East Mumbai, drinking water tunnels were proposed by MCGM from Amar Mahal to Trombay reservoirs, Amar Mahal to Wadala and further up to Parel. The pipeline has to be underground and laid at a depth of 5.5m. The initial proposal was to provide sheet piling to enable the safe excavation and installation of underground pipeline. However, installation of sheetpiles was practically not feasible due to the existing soil strata for driving the sheet piles. Hence, it was proposed to install micropiles instead of sheet piles. In this paper we discuss about the purpose, basic design, detailed design approaches and actual work implementation of micro pile with temporary struts for shoring protection works in this project.

Sep 1, 2022

By Kozo Takeda, Arashi Shimano

"Dry Jet Mixing (DJM) technique is widely known as soil mitigation technique with small ground displacement during installation comparing with other techniques. Some projects involving sensitive structures, however, require smaller impact than in conventional technique. In order to reduce ground displacement during DJM installation, this paper introduces systematic mixing technique, RD-DJM (Reducing Displacement – Dry Jet Mixing). RD-DJM is characterized by injection nozzle on the rim of mixing blade and fin plate on mixing shaft. These devices contribute efficient collection of injected air toward mixing shaft and result in reduction of ground displacement. The authors demonstrate successful performance of RD-DJM indicating difference between conventional installation and RD-DJM technique.INTRODUCTIONThe Dry Jet Mixing (DJM) method is one of the most common techniques in Japanese deep soil mixing field and characterized mechanical mixing of powdery binder with in-situ ground (dry-mixing technique). It is widely believed that DJM Method has great advantages in less quantity of binder to achieve the desired strength and less waste generation during installation.DJM method can meet the required strength with less binder content than wet mixing. And volume of binder of dry mixing is absolutely less than wet-mixing injecting considerable volume of binder slurry. This means that dry mixing causes less ground displacement compared with wet mixing.As the medium for forced feeding of the binder, the DJM method uses compressed air, which is blown from the mixing blade nozzles to scatter the binder and then recovered through the periphery of the mixing shaft to the ground surface. Because the binder is injected outward from the injection orifice at the root of the mixing shaft, a part of the air may escape to untreated areas due to the blockage of air recovery path around the mixing shaft. Figure 1 illustrates possible escaped air and leakage around installation location."

Jan 1, 2015

By Mark Zablocki, Dakarai McCoy

Ground vibrations are an unavoidable effect of driving piles and may pose a risk to nearby infrastructure and the comfort of adjacent occupants. Driven-pile-induced ground vibrations are known to vary widely based on ground conditions, pile material, and installation means and methods. A monitoring sensor to record ground vibrations during pile driving is necessary for understanding potential impacts to sensitive infrastructure and should be considered when implementing a monitoring program anticipating ground vibrations. The implementation of a vibration monitoring program historically relies on experiential-based decision-making, which may result in the costly vibration monitoring of low-risk infrastructure. Prior understanding of anticipated ground vibrations is necessary to create an appropriate monitoring program. A framework is proposed for organizing data from past monitoring programs and quantifying the anticipated risk of driven-pile-induced vibrations. An example of risk quantification from data imported to ]a cloud database is presented by comparing driven steel H-pile and prestressed precast concrete vibration monitoring measured and collected by Haley & Aldrich between 2010 and 2020. The methods presented within the example can be applied to quantify a first order approximation of risk for ground vibrations at proposed driven pile sites based on the measured performance of previous sites with similar ground characteristics and pile installation methods. The presented novel data managements tools allow for a quick aggregation of vibration data with similar site conditions.

Sep 8, 2021

By Jim Bruce, Naresh Gurpersaud

"The West Toronto Diamond project, under construction since 2006 and due to be complete in 2015, is a rail-to-rail grade separation project in the heart of urban Toronto. Once complete, a depressed corridor over 1000 metres long will take the CN tracks beneath the CPR tracks. An interlocking steel pile wall serves to retain ground and cut off groundwater. Remedial measures, constructed using jet grouting, were required at several locations within and behind the steel piles.At mechanical interlock joints damaged or suspected of being damaged, jet grouting was used to improve native soils on the retained side of the wall to reduce permeability of the soil mass in intimate contact with the joints to 10-7 cm/s. At a number of steel piles where groundwater and soil type combined to cause basal instability inside the pipes during the interim between excavation and concreting, jet grouting was used to construct temporary bottom seals. At locations near adjacent structures where the steel pile installation process resulted in disturbed ground on the retained side of the wall, jet grouting was used to strengthen and stabilize ground.This paper outlines the details of the various jet grouting applications, the respective testing programs implemented to demonstrate in situ permeability and strength of the soil-grout matrix, and performance of the constructed system.INTRODUCTIONThe West Toronto Diamond (WTD) is a junction of several railway lines, all intersecting at the same grade (Figure 1). A major grade separation project at this site commenced in 2006 and is scheduled to be completed in 2015. The whole of the work is comprised of multiple contracts, completed and/or ongoing, by different constructors. Once completed, a depressed corridor over 1000 metres long with over 23,500 m2 (face area) of retained earth will bring the CN tracks beneath the CPR tracks and eliminate a major bottleneck at the most heavily used rail crossing in Canada."

Jan 1, 2017

By Toshio Yonezawa, Helmut Florian, Herbert Kuh, Masamichi Aoki, Takao Koono, Franz-Werner Gerressen

"To increase the bearing capacity of the ground, soil improvement technique is often adopted. One advantage of soil improvement techniques is the fact, that the impact to the environment is low, as the system utilizes the existing soil. Recently, compressive strength of soil improvement gets more into the focus for the use of building foundation. To prevent brittle fracture, which is a weak point of soil improvement, fiber reinforced soil improvement has been developed. Laboratory tests were conducted to examine the fibers suitable for reinforced soil improvement, and examine the optimum mix design for fiber cement slurry. Based on the laboratory tests, polypropylene fiber and cellulosic viscosity admixture was selected. For the laboratory tests a scaled model of CSM mixing head was used to examine the dispersion of the fibers in the ground. Using the CSM mixing head, the outer periphery fibers of soil improvement seemed to be arranged in the vertical direction, toughness performance of the soil improvement could be improved. Furthermore, full scale field test was performed using actual CSM unit, modified to enable the use of fiber mixed slurry. The validity of the material as well as the toughness performance of the soil improvement, determined from lab test results, was confirmed. In addition, it was confirmed that fiber reinforced soil improvement can be constructed appropriately by CSM method.2 INTRODUCTIONSoil improvement technique to improve the strength and deformation performance of ground has been used for a long time. Cement improved methods, with the increase of the deep Mixing Method, which has been disseminated since the 1970's, was often used since. Cement used soil improvement technology has been utilized to stabilize excavations, slopes in embankment and much more. Recently, it can be used for preventing liquefaction by building soil improvement in a grid (Suzuki et al. (1996)), and also as basis of the structure by increasing the compression strength of soil improvement (Yamashita et al. (2011)). Cement used soil improvement method, a technique for mixing the in-site soil and cement, can effectively utilize natural resources, and it can be expected that its use will increase further in the future. Therefore, soil improvement technique will be able to minimize the impact on the environment. Cement improved soil is a mixture of soil particles and cement with high compressive strength but low tensile strength. Since tensile strength of soil improvement is low, brittle destruction occurs. Therefore, it is not possible to use soil improvement in conditions acting with bending stress. If a horizontal impact force occurs in the improved soil, the width of the soil improvement needs to be increased to reduce the bending stress. If preventing the brittle fracture of soil improvement, the width of soil improvement could be reduced, then less resources would be needed. In order to increase the tensile strength of the soil improvement, several studies for the mix of fiber and soil were performed. Victor (1992) indicates cracking deterrent effect by fiber based on laboratory tests. Moreover, based on laboratory tests, Hayasaki (1982) illustrated the effect on the tensile strength of the fiber types, the type of fiber, the diameter of and the length of fiber."

Jan 1, 2015

By Yoshinori Kurumada, Masaya Watanabe, Kenji Sasa

"The Port of Yokohama is strengthening its international competitiveness as a strategic container port in order to respond appropriately to global exchange and shipping demands. Thus, the Minami Honmoku main Pier is currently being developed. The high-standard container terminals MC-1 and MC-2 have already started their service, and the development of the container terminals MC-3 and MC-4 is currently in progress.Because the South Honmoku Pier plays an important role in waste disposal management of Yokohama, a final waste disposal site (controlled final landfill site) is being developed in Block 5 to provide long-term and stable reception of waste that will be generated in the city. For this project, a revetment with water-blocking properties and an extension approximately 1.7 km in length is being built in order to prevent water from leaking from the disposal site. The base part of the revetment will be subjected to foundation improvement using the Cement Deep Mixing (CDM) method in order to secure water shielding of the soft sediment underneath the water, prevent slipping of the seawall, reduce the amount of subsidence, and increase the foundation support force.This report presents a preliminary study on using CDM on reclaimed soil and the construction process of the development project of the disposal site in Block 5 of the Minami Honmoku Pier, which has been underway since 2007.ABOUT MINAMI HONMOKU PIERThe development of the Minami Honmoku Pier started in 1990. It was designed to develop high-standard berths with greater water depths in order to handle the increasing volume of foreign container cargo and growing size of vessels. Figure 1 shows the layout of Minami Honmoku Pier. In April 2001, the Phase 1 (MC-1 and MC-2) began services. This is the newest pier in Port of Yokohama.This pier has one of Japan’s largest terminal areas (40 ha) and is equipped with 22 row-type mega gantry cranes capable of handling the newest ultralarge container ships. The pier has a quay with a water depth of 16 m, which is the first in Japan. The pier is equipped with advanced facilities and equipment to let Port of Yokohama be internationally competitive and function as an international commercial hub. An innovative system for high-efficiency transport is currently being introduced; it includes the installation of waiting vehicle lanes and a reservation-based loading and unloading system.Since the fiscal year 2007, a new container terminal (MC-3) with a -20m deep quay capable of handling the increased size of container ships and the diversification of port logistics has been under construction and is nearly completed."

Jan 1, 2015

By Gerald Verbeek, David Tara

"When selecting an impact hammer to drive a particular pile, the decision is often based on local experience. In those cases, the contractor falls back on previous experience or draws on the experience of the hammer manufacturer to select the hammer that will be able to do the job. Obviously, a more scientific approach would be to perform a pile driving simulation using one of several commercially available software packages (e.g., GRLWEAP, AllWavePDP or PDPWave).However, this type of analysis requires quite a bit more effort. First, an accurate model of the pile driving process has to be developed, which includes a model of the soil profile at the job site and input into the analysis program. Then, the model must be analyzed to assess whether the combination of hammer, pile and soil model work.Over the years, numerous individuals and organizations have tried to develop something that would fit nicely in between these approaches: something more advanced than a gut feeling yet something that could be done on the back of an envelope; in other words, a “Goldilocks” approach — not too simple, not too complex, but just right.Screening Tool CriteriaThe goals of the approach are twofold: (1) select the appropriate impact hammer to drive an open toe steel pipe or H-pile, and (2) then use the model for the subsequent high strain dynamic testing (HSDT). The Goldilocks approach centers around five different criteria.1. Maximum Driving StressTo minimize the risk of damage, the maximum driving stresses are generally limited to 80 to 90% of the yield stress (fy) of the steel section. This approach does not consider issues such as hammer alignment, initial imperfections, denting and/or elastic buckling, and pile material fatigue history. However, even when these issues are not applicable, limiting average stresses to 0.9fy or even 0.8fy does not necessarily mitigate the risk of pile damage (Mostafa, 2011)."

Jan 1, 2017

By Gustav Jahner, Michael Baltrusch, Norbert Hoffmann

Near the port city of Whitby in the north-east of England, Anglo American (AA) is setting up the deepest mine in the UK, which will have a depth of 1,500m. The purpose of the project is to extract and transport polyhalite, both underground, and to market it globally. As part of the construction works, BAUER Technologies Ltd, the UK subsidiary of BAUER Spezialtiefbau GmbH, constructed three different shafts using the diaphragm wall technique, with depths of up to 120m. In order to ensure the specified vertical tolerance of maximum 200mm, several measurement methods were applied, and the results were documented in a 3D model. Complex de-sanding plant technology and specially developed polymer products were adopted to regenerate the trench supporting bentonite-slurry.

Sep 1, 2022

By Richard Stone, Rouzbeh Afsharhasani, Moses Karakouzian

"Caliche, a hardened sedimentary deposit of calcium carbonate that occurs worldwide, generally in arid or semiarid regions, is frequently encountered in Las Vegas, Nevada. The presence of a caliche layer in a soil profile affects the response of deep foundations to axial load. This paper studies the stiffening effect of caliche layers on the elastic settlement of a pile foundation. In order to evaluate the response in a layered soil-caliche profile, finite element analyses were performed on a typical-sized single pile and a pile group, both having constant diameter and length of the pile. The results indicate that the stiffening effect from the caliche is noteworthy, and a layer with a relative thickness of at least one pile width, regardless of its location, reduces the pile settlement for both single piles and group of piles systems by at least 50%.IntroductionThe presence of cemented materials in the soil profile influences the settlement response of foundations. One type of cemented material that can be found in arid places around the world is a sedimentary deposit of calcium carbonate called caliche. Caliche, a hardened sedimentary deposit of calcium carbonate, is common in arid and semi-arid urban areas, such as Las Vegas, Nevada (Wyman, et al. 1993).Caliche is mostly observed in lacustrine, river, and alluvial fan deposits (Jr.C.C 1970). It is also found in Central and Western Australia, the Kalahari Desert, the High Plains of the Western U.S., and the Sonoran Desert of the U.S. and Mexico.Some conditions required for the formation of caliche are that country or basement rocks must be a carbonate type, carbonate must be present in the soil zone of the area, climate regime is semi-arid to arid, there exists widespread capillary activity, and carbon dioxide (CO2) is present in the environment. As a result, caliche occurs as a product of the carbonization process (Atabey, Atabey and Kara 1998). In such areas where foundations are constructed on thin rock layers (caliche), special geotechnical design conditions should be considered, particularly if the supporting rock layer is underlain by a weaker material."

Jan 1, 2015

By Mary Ellen Bruce

Let me first address the issue of the wet grab samples. The wet grab samples that were attempted to take on the Central Artery were hindered by the fact that the way the mixing was being done was only by injecting grout on the way out, during withdrawal of the mixing tools. They would auger down to the required depth (usually with some water being injected), which took anywhere from 45 minutes to an hour, and then when coming out, the grout would be injected with grout. That was leaving a column of grout in the center where the shaft had been (i.e. inside of the blades of the mixing tools), which would end up being something like a foot in diameter because the pipe that was used for the drill shaft was a foot in diameter. So we had 10 inches to a foot of almost pure grout in the middle of our column and then we had 2 feet on either side that was mixed soil cement. So when they went down with the wet grab sampler not knowing where that was in the column sometimes they/we were getting strengths of 1500 psi, and sometimes they/we were getting strength of 500 psi or 100 psi. So what was it that we were taking into the wet grab sampler? In those cases you don't really know, but it wasn't representative of the core samples we were taking. We were purposely not coring in the center because we knew that was going to be high cement content, almost pure grout. So the issue of wet grab sampling particularly on this project, the Central Artery Project, was that we didn't really know what we were sampling. What becomes an issue with wet grab sampling in other projects is that you have to have another device (machine) in most cases, a cherry picker crane or something similar that can raise and lower with a beam that is used to forces the sampler down into the freshly mixed soil-cement. And regarding economics, is it more economical to have that crane standing by with its operator or to have a drill rig to come along later and do the coring and take the material out that's fairly identical to what you're finding in situ? The complaint of micro-fracturing in the core samples as you're taking the cores was raised by Seiko as causing large strength reductions. But, if you're doing it carefully, then I don't think that's much of an issue anymore, on research basis perhaps but not on a practical level.

Feb 10, 2003

By Pratter P., Boley C.

Polymers are well established in geotechnical applications, for example in ground improvement, where the polymers act as a binder that, when cured, holds the grains together by adhesive and cohesive forces. The subject of this research work is an innovative composite of polymers and gravel, which differs from conventional grouting materials due to its adjustable material properties. With these specific properties, the semi-rigid material can be optimally adapted to the local ground conditions and the individual framework conditions of a construction project. For the characterization of the composite material, stateof- the-art methods, such as image processing by segmentation, are presented. Segmentation is suitable for quality assurance and monitoring of laboratory samples and soil samples directly from ground improvement on the construction site. The load-bearing capacity of the innovative material can even be increased to the order of magnitude of concrete. For this reason, the soil mechanical laboratory tests in this research had to be modified and even expanded by rock mechanical laboratory tests. Based on the experimental investigations, the importance of this innovative material for practical application is demonstrated by a calculation example from construction practice, which shows that even difficult ground conditions can be handled with it.

May 1, 2022

By Amr Sallam, David Thompson, Moataz Hassan

"The Little Lake Harris (LLH) Bridge was constructed in 1951 to replace the eastwest County Road 48 Bridge connecting the towns of Howey-in-the-Hills and Astatula in Lake County, Florida, United States. The 78-span bridge carries two lanes of traffic, is 3,130 feet long, and 36.1 feet wide. The concrete deck is supported by steel I-girders carried by one row of 18-inch square precast concrete driven pile. In the late 1980's, slight settlements were observed in several bents. In 1990, Florida Department of Transportation (FDOT) initiated annual survey of deck elevations during bridge inspections to monitor settlement. Due to the slow nature and magnitude of settlement, substructure instability was not a major concern to the department. However, public concern over the settlement and rough ride of the bridge continued to rise. FDOT contracted Kisinger Campo & Associates Corp. (KCA) to provide the needed design to correct the dips in the riding surface and minimize future settlement. KCA's initial design was based on the concept of ""helper bents"" at the settled bents in order to restore the bridge to original elevation. Estimated construction cost for seven helper bents was about $3.3M. FDOT requested evaluating other alternatives to reduce the cost of the bridge restoration. KCA involved the geotechnical consultant, Terracon Consultants, Inc. (Terracon), to perform a peer review and provide an economical alternative solution. Jacking and shimming the bridge was determined to be both technically viable and economical with a total cost of less than $300K. The design was completed in March 2010 and construction was completed in February 2011. This paper provides an overview of the LLH Bridge history, summarizes the evolution of the design methodology including the findings of the geotechnical study and presents lessons learned during the design and construction of the project.INTRODUCTIONThe Safety and Preservation of the State Highway System is the top priority of the FDOT. Therefore, FDOT initiated a bridge management program that starts with conducting biennial safety inspections performed by Certified Bridge Inspectors (CBI). The inspection reports together with the CBI’s recommendations are reviewed by a registered Professional Engineer (PE) and work orders are issued with priority ranking depending on the severity of the bridge deficiencies. If the scope of work is considered beyond the in-house crews’ capability, the work is then included in a contract for and bid. LLH Bridge was a little different. It was initiated in direct response to number of complaints the FDOT District 5 Structures Maintenance Office (D5SMO) received regarding settlement of the Little Lake Harris Bridge."

Jan 1, 2015

By Nicolas Denies, Jeroen de Leeuw, Bart Lameire, Jan Maertens, André Vervoort, Flip Hoefsloot, Noël Huybrechts, Flor De Cock

"In recent years, the Deep Mixing Method has increasingly been applied for the construction of earth and water retaining structures. From practice, it has been experienced that there is a real need to develop execution and design rules adapted to the function of the soil mix wall (retaining wall, water barrier, foundation solution or a combination) including the temporary or permanent character of the application. Based on the results of the BBRI Soil Mix project (2009-2013), a design approach has been developed in collaboration with the SBRCURnet. The present paper briefly discusses the principles of this design approach which takes into account the function of the soil mix wall and the characteristics of the soil mix material. The interaction between the soil mix material and the steel reinforcement can be considered in the calculations depending on the function of the soil mix wall. Design and quality control requirements are given in function of the application and take the lifetime of the structure into account. Durability aspects of the soil mix material are therefore considered in the present design approach.INTRODUCTIONSince several decades, the deep mixing method is used for ground improvement works. A more recent application is the use of soil mix as structural elements such as in the case of the earth-water retaining soil mix walls. Since 2000, due to the economic and environmental advantages of the method, this particular application has shown an amazing growth in Belgium and in the Netherlands. A typical excavation (16 m depth), realized with CSM (Cutter Soil Mix) panels, is shown in Fig. 1. For temporary applications, the questions related to the mechanical characteristics of the material, its permeability and its adherence with steel have been investigated with success within the framework of the BBRI Soil Mix project (2009- 2013) (see Denies et al. 2012 for more details). The durability of the soil mix material remains a complex topic while permanent applications are more and more observed in practice. In order to define an obvious design approach, it was necessary to clarify the potential functions of soil mix walls and to establish the requirements related to their design and construction. The BBRI (in Belgium) and SBRCURnet (in the Netherlands) have therefore worked together to publish guidelines in the form of a handbook titled ‘Soil Mix Walls’ (publication foreseen in 2015). In this handbook, a methodology is proposed for the design of the soil mix walls for which the interaction between steel and soil mix can possibly be taken into account dependent upon the application. Each potential function of the soil mix wall is described (e.g. earth retaining wall, cut-off wall, etc.) and the temporary or permanent character of the application is always considered."

Jan 1, 2015

By Abid Adekunte

"Whilst safety is considered to be of high priority in every aspect of engineering projects, it is equally important for designers and contractors to be continually aware of their obligations to the immediate environment and the society as a whole. These include responsibilities to minimise the amount of nonrenewable natural resources and energy used on projects, to reduce carbon foot prints on projects, to minimise the quantity of wastes produced on projects, to minimise the level of pollution on construction sites and to reuse materials and waste products whenever and wherever possible.In other words, professional engineering practice needs to be accompanied by an underlying fundamental objective to improve, restore and sustain the environment. However, achieving this objective requires continuous collaborative interaction and effective communication between the different specialists involved on every project from the early stages. In addition, developing a well-thought-out economical solution is key to achieving the sustainability aspect of the above objective.This paper focuses on the design, construction and management of a recently completed large multi-level basement scheme in Central London, with greater emphasis on collaborative approaches taken by the design engineers, commercial managers, construction managers and site operatives to deliver the most reasonably economical and sustainable solutions to the client. Solutions were based on combinations of general and specialist engineering knowledge, with due considerations for health & safety, sustainability, cost, practicality, time and community requirements.INTRODUCTIONUnderground structures have become vital components of urban life worldwide e.g. tunnels serve many water, wastewater, highway and railway schemes, basements have been incorporated into many urban commercial, institutional and residential developments, while many public underground car parks have been built to deal with the incessant problem of insufficient surface parking spaces in busy urban centres.The safe design, construction and maintenance of underground structures have been well-mastered by the deep foundation industry over the years. However, just like many other areas of engineering, aside the need to satisfy safety requirements, underground construction practice is now faced with a new set of requirements; the demand for more sustainable and cost-effective solutions, with reduced environmental and societal impacts. Designers and managers of underground construction schemes are now compelled to minimise the use of natural resources and energy, to minimise the amount of waste produced, to minimise the level of environmental pollution, noise and disruption to traffic and normal societal life at ground level around underground construction sites. In addition, the recycling of site wastes and reuse of materials have now become important aspects of underground space development. Considerable effort is being put into promoting sustainable development across the industry."

Jan 1, 2017