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By Adnan A. Malik, Tadashi Maejima, Jiro Kuwano, Shinya Tachibana

"The helical piling system provides solution to many geotechnical related problems due to its quick installation, higher compressive and pullout resistance, no wastage of material, workable in limited areas and reusability. However, its use as a foundation for bridges and high-rise buildings is still limited as compared to other piling methods. In the present study, the performance and load settlement behavior of screw and straight pile is investigated under cyclic compressive load in dense ground conditions. To achieve the set objectives, pile load tests were conducted in a cylindrical steel container. The model ground was compacted with dry sand at relative density of 80%. It is observed from the test results that screw and straight pile resistance reduced when the cyclic load is applied at allowable pile resistance state. The reduction in the ultimate pile capacity is more in straight pile than in screw pile. However, straight pile showed higher ultimate pile capacity than screw pile under similar pile tip diameter. The effect of helix bending deflection on load settlement behavior and ultimate pile capacity increases under cyclic loading.INTRODUCTIONScrew pile is one of the new developments in deep foundation, which is growing tremendously fast because of its quick installation technique, less noisy operation, no wastage of material and involvement of minimum manpower. Screw piles have an edge on straight pipe piles due to its high bearing capacity and uplift resistance. The installation mechanism of screw pile is different from straight pile. Torque and pressure is required to install the screw pile whereas hammering, pressure and vibration is required to install straight pile. As the installation mechanism is different between screw and straight pile, therefore, the ground disturbance that is produced during their installation is also different. The ground disturbance produced during the installation also depends upon the pile tip condition i.e. open or closed ended. Sakr, (2009) stated that the compressive capacity of screw pile in 3 to 5 times higher than driven piles having the same shaft diameter and length. The reason for this increase in pile capacity is due to helix, which is generally 2 to 2.5 times the pile shaft diameter. Larger helices can give higher end bearing capacity but it requires very powerful machinery to install in dense grounds. For instance, if large helix screw pile is installed in a dense ground then helix-bending deflection will start affecting the end bearing capacity (Yttrup and Abramsson, 2003; Malik et al. 2013 and 2015). According to Malik (2015), the equations of thin plate (Young and Budynas, 2002) with uniformly distributed load on the plate can give reasonable estimation of helix deflection due to dense ground conditions."

Jan 1, 2016

By K. Ronald Chapman, Claus Ludwig, Doug Jenevein

"In the spring of 2005 Schnabel Foundation Company completed a $15.2 million Design/Build subcontract to underpin 11 structures, and provide 202,800 square feet of earth retention for the Reno Transportation Rail Access Corridor (ReTRAC) project in Reno, Nevada. Schnabel’s work was part of a Design/Build contract to depress a railroad alignment through downtown Reno. The depressed section was 2.2 miles long, 54 ft wide, and up to 35 ft deep (3.5 km long, 16.5m wide and up to 10.7m deep). The trench structure was required to be watertight. SUBCONTRACT WORK OVERVIEWEleven buildings along the track alignment required underpinning. Three types of underpinning were used, designated Type 1, Type 2 and Type 3.At four buildings the trench retaining walls were to be located directly under the exterior footings. This alignment eliminated traditional underpinning and cut-off wall techniques that could normally be used to support structures. Type 1 underpinning was used at these buildings. This underpinning system consisted of a combination of permeation grouting, hand-dug piers, and permanent tiebacks. This underpinning system became the new watertight trench walls.Five buildings were located a few feet behind the trench walls, and their exterior walls were supported by continuous footings. Type 2 micropile/pile cap underpinning (patent pending) was used to support these buildings.The remaining two buildings were also located a few feet behind the trench walls, but they had column footings along the exterior walls. At these structures traditional micropile underpinning was provided through the existing footings. This is described as Type 3 underpinning.Temporary earth retention was required on both sides of the trench along most of the alignment. This shoring supported frontage roads, private property and surcharge from the temporary railroad shoofly running parallel to one side of the trench.SUBSURFACE CONDITIONSThe soil along the trench alignment consisted of river outwash deposits. The top 2 to 18 feet (0.6m to 5.5m) generally consisted of flood plain silt and sand deposits, or fine-grained fills. These fine-grained soils are underlain by the Tahoe Outwash Formation which consists of interbedded layers of sand; sand and gravel; and sand, gravel, cobbles and boulders. Some of these layers encountered during construction consisted of 30 to 50 percent cobbles and boulders, with some boulders up to eight feet in diameter.A major challenge to the design and construction of the trench structures and the underpinning was the ground water table which was 10 feet (3m) above subgrade in the deepest portions of the trench. Based on specification restrictions, temporary and permanent dewatering was not feasible. As a result, the selected design and construction methods had to consider three water conditions: the anticipated groundwater level during construction (CGW), the groundwater level for permanent design (DGW), and an additional special design condition with water at street grade."

Jan 1, 2006

By Kirty Dave

Foundations in any contract are the most uncertain parts of the contract and most of the "Construction-Contract-Disputes" are either directly related to foundations or arise as 'Side-effects of changes in promises related to foundations. Foundation Engineering is defined as ' The art of selection, designing and constructing the elements that transfer the weight of structure to the underlying Soil or Rock." (Ralph B. Perk). This art started becoming a science since 1920, when scientific efforts to determine the behaviour of sub-surface materials were made. The art and science merged to give new techniques and the science started dominating the field as more and more refinement came in techniques to predict more accurately the characteristics of the sub-surface elements. Inspite of good thorough investigations and design, the contractual promises drafted could leave some room for differences between the parties and above all the prudency expected of both the parties may fall short of the expectations raised in the contract. This may give rise to disputes which may need to be resolved as per principles of law. This paper attempts to initiate a dialogue amongst Foundations-Engineers and Contractors as to how do we minimise the differences arising out of or related to contracts concerning "Foundations".

Jan 1, 1996

"1.0 DESCRIPTIONThis work consists of furnishing all necessary labor, equipment, and materials to install prefabricated vertical (wick) drains in the ground in accordance with the Plans and as specified herein.2.0 REFERENCED CODES AND STANDARDSASTM D4716-08 Standard Test Method for Determining the (In-plane) Flow Rate per Unit Width and Hydraulic Transmissivity of a Geosynthetic Using a Constant HeadASTM D4632-08 Standard Test Method for Grab Breaking Load and Elongation of GeotextilesASTM D4533-11 Standard Test Method for Trapezoid Tearing Strength of GeotextilesASTM D4491-99a Standard Test Methods for Water Permeability of Geotextiles by Permittivity (2009)ASTM D4751-04 Standard Test Method for Determining Apparent Opening Size (A.O.S.) of a GeotextileASTM 6918-09 Standard Test Method for Testing Vertical Strip Drains in the Crimped Condition3.0 QUALIFICATIONSThe Contractor shall have successfully completed a minimum of five wick drain installation projects in similar ground conditions, and installed not less than 5,000,000 linear feet (1,525,000 linear m) of wick drain in the past five years. The Contractor shall have a minimum of five continuous years of wick drain installation experience."

Jan 1, 2014

By Clifford Taylor, Alexander Zöhrer

"The execution of deep basement excavations under narrow conditions is one of the most challenging tasks in geotechnics. The vicinity of neighbouring buildings, roads, and underground structures such as sewers or power lines, quite often prohibits the application of standard solutions. In addition, legal considerations in the use of adjacent properties is becoming increasingly difficult. This paper will present some innovative approaches to overcome the above-mentioned challenges based on several case studies from central Europe. For every project the design approach as well as the techniques used for execution will be explained, detailing both the advantages and the limitations of the applications. One case study shows a deep basement excavation (approx. 17m) in the centre of Prague, Czech Republic. This project featured many challenging boundary conditions (narrow construction area, high ground water table, jet grouting column embedment into bedrock, constraints regarding use of ground anchors due to property rights, etc). The realisation of the complex design is described and illustrated in detail. Other case studies will show the combined application of bored piles with jet grouting and also explain the design of vertical prestressed anchors for retaining walls.INTRODUCTIONThe development of urban areas has always presented challenges, from access for equipment and materials to the rectification of existing foundations in unknown condition. Compounding these is the increasingly stringent requirements to retain, maintain and reduce impact on culturally and historically significant structures. As available space is becoming more limited, optimisation of real estate has resulted in buildings getting higher and their basements deeper below ground. Two or more basement levels are quite common, with typical excavation depths ranging from 5 to more than 10m. Additionally, we are faced with neighbouring buildings that are equally high, deep and massive. These buildings directly adjacent the retaining structure require underpinning to limit settlement, and in cases where they are within just a few meters, this building mass generates additional earth pressure for the retaining wall to support, resulting in complex loading cases.This paper highlights several common challenges and explores the measures implemented to overcome them. The challenges and examples of either design based solutions or practical applications will focus on the following topics – the limitations of conventional geotechnical construction methods, overcoming challenging geology and the requirement for watertight basement constructions."

Jan 1, 1900

By Charles M. Wilk

"Mass stabilization involves mixing binding agents into marginal or contaminated soil to improve the subject material’s physical and/or chemical properties. This paper concentrates on the principles of soil mixing and benefits and application to new and existing rail right-of-way. Successfully applied in Scandinavia and other European countries, the soil mixing is now being applied in right of way in the northern latitudes of the U.S. and Canada. These regions have significant areas of “peaty” soils that can complicate construction and maintenance of rail and structure foundations. Mass stabilization can be used to improve the bearing strength of these soft soils for subsequent construction of railroads, pipelines, roads, and buildings. In civil engineering, the technology is often used to improve the construction properties such as bearing strength, of a marginal soil. In environmental engineering, stabilization is remediation treatment technology that protects human health and the environment by immobilizing hazardous constituents within the treated material. . The treatment is conducted while the subject material remains in-place (insitu). Mass Stabilization is often used to accomplish both civil and environmental purposes on the same project effectively addressing marginal soil while eliminating the expense of soil removal and replacement. This paper presents the principles of mass stabilization technology, implementation in the field and recent completed railway projects. The example rail projects will present the various benefits that soil mixing provides to railway construction and maintenance. Bench-scale studies and full scale implementation as well as soil construction properties before and after mass stabilization will be discussed. The paper and presentation will include information on the advantages of mixing methods and binding agent delivery systems.INTRODUCTIONNew or existing railroad right-of-ways may cross ground with low bearing capacity. Right of way subgrade undergo deflection (strain) as loads (stress) are applied. The amount of strain or deflection of the subgrade caused by loading of a train is proportional to the stiffness of the subgrade materials. Some soils, such as tamped ballast, are very stiff and resist loads well. Other soils such as soft clay, peat, or loose sand have low stiffness and undergo substantial movement under loads. It is very desirable to have the stiffest possible material in a track subgrade. Stiff subgrade material limits deflection under load, reducing track roughness and occurrence of track defects. Mass stabilization is a geotechnical method that can be used to improve the bearing capacity or stiffness of soil in these right-of-way. Mass stabilization involves mixing binding agents into soil subject to treatment while the soil remains in-place or insitu. Variations in the design or areas subject to treatment can be used to address transmission of vibration to adjacent structures."

Jan 1, 2015

By Sung-Ryul Kim, Woong-Jong Park, Juhyung Lee, Si-Hoon Lee

"A bucket foundation has been considered to be a potential foundation technology for offshore wind turbines. In this study, a series of 1-g model tests were performed to analyze the accumulated rotation of suction bucket foundations under long-term cyclic horizontal loads. The model suction buckets were made to have the embedment ratios of 0.5 and 1. The dry model ground was prepared to have two different soil densities by air-pluviation method. A horizontal cyclic load over 104 cycles was applied varying the loading amplitude. Test results showed that the accumulated rotation of the bucket foundation increased with the increase in the number of cycles and load magnitudes. Based on the model test results, a new equation was proposed to evaluate the accumulated rotation of the bucket foundations in sandy ground under long-term cyclic horizontal loads.INTRODUCTIONRecently, a bucket foundation has been considered to be a potential foundation technology for offshore wind turbines. In terms of economy, a bucket foundation has been considered to be an economical foundation type at sea beds where ground condition is clay or medium dense sand.A bucket foundation resembling a bucket is a kind of suction-installed foundation units. It is a skirted steel foundation which is open at the lower end and closed at the upper end by a lid. The embedment depth ratio (L/D) of a bucket foundation is usually less than one. Figure 1 shows an example of a bucket foundation. Offshore wind turbines are subjected to long-term cyclic loading by wind or currents. A bucket foundation is installed in soil grounds, so the long-term cyclic loading may induce the accumulation of soil deformation.In this study, the accumulated rotations of the bucket foundations in sandy ground were investigated under long term cyclic horizontal load. The number of cycles up to 104 cycles was applied varying load magnitude. The accumulated rotations of the bucket foundations in sandy ground were analyzed based on the test results."

Jan 1, 2016

By Wolfgang G. Brunner

Mai- Liao, in Yun Lin province of Taiwan, which was once a remote area on the coast of the South China Sea, has been developed into an offshore industrial complex. Approximately 100 million m3 of imported sand fill were used to reclaim the site from the sea with an overall area of almost 3.000 hectares. Land reclamation started in March 1994 and was completed at the end of 1998. A total of 41 industrial plants were constructed on the site, including an oil refinery, a naphta cracking plant, a cogeneration plant, a coal- fired power station, a heavy machinery plant, a boiler making plant, water purification plant, several petrochemical plants and a new harbour. From 1998 onwards, new plants were taken into operation in uninterrupted succession. The main purpose of the ground improvement by vibro- displacement, used predominantly to form the foundations of the oil storage tanks , was to reduce the liquefaction potential of the subsoil during earthquakes. The top layer across the site was treated by dynamic compaction before the installation of the stone columns. Heavy structures such as chimney- stacks and buildings were constructed on pre- cast concrete piles driven by diesel hammer. The earthquake design criteria specified an earthquake magnitude M = 7.3 and an acceleration a = 0.21 g. Stone columns were installed by the dry bottom feed process, which was controlled by an automatic monitoring system, to depths ranging from 13 to 20 m to provide flexible tank foundations. Installation of 1.500.000 linear m of stone columns commenced at the beginning of 1997 and was completed in August 2000. 60 % of the stone columns, in particular the deep ones, have been carried out by Bauer vibrators. The Chi- Chi earthquake ( M = 7.3 ) took place on 21 September 1999 and was followed by Cha- I earthquake ( M = 6.8 ) on 22 October 1999. A survey carried out after these earthquakes showed very positive results. The maximum observed settlement was 10 mm and none of the tanks suffered any damage.

Jan 1, 2002

By Glen R. Andersen

"Two of the greatest challenges we face in managing our aging infrastructure are to perform accurate condition assessments and to realistically predict the risk of non-action. The aim of this paper is to discuss common pitfalls we face in performing accurate condition assessments of our aging infrastructure using the case history of a recent near miss at the Lake Manatee Dam in Central Florida. The dam was placed into service in 1967 and was inspected every couple of years by dam safety engineers beginning in 1978. Although there was substantial and repeated evidence of a serious piping and internal erosion problem in each of these inspections, the problem was overlooked by most of the inspection teams. In 2012, the inspection team concluded that: “the Lake Manatee Reservoir Dam is well maintained and is in very good overall condition.” However, in 2013 a new team inspected the dam from an entirely different perspective, identified potentially serious conditions, performed an integration of the historical inspection data and concluded that: 1) the Lake Manatee Dam was in a severely distressed state; and, 2) without an immediate intervention there was a high risk of an uncontrolled release of the reservoir most likely following a large rainfall event and prolonged opening of the service spillway. This case history highlights human factors contributing to the near miss including group think and focusing on changes from prior inspections. The integration of historical inspection data is recommended for managing our aging infrastructure.INTRODUCTIONThe engineering analytical techniques most appropriate for assessing an aging infrastructure can be distinct from those used for the original design. To adequately manage our aging infrastructure it is necessary to change our perspective from anticipating failure mechanisms and designing to prevent them to assessing condition, detecting the presence of potential failure mechanisms, and assessing the potential risks. In many circumstances the failure mechanisms currently active may not have been anticipated by the original design team.We have developed a substantial body of experience in the design of our infrastructure. Full scale and laboratory testing coupled with the application of scientific principles to model behavior has led to many powerful design tools. The continued serviceability of our infrastructure as its elements reach their design lives stands as a legacy to our profession. However, under the sustained effect of limited resources for maintenance and rehabilitation parts of our infrastructure are in a highly deteriorated state. Unfortunately, the condition of some of these has not been properly assessed. This paper focuses on the Lake Manatee Dam in Central Florida and the process used to clearly identify its highly deteriorated state. While there are many factors that contributed to the lack of a proper assessment of its condition, the focus herein will be on human factors and in particular how “Group Think”, “Aversion to Bad News”, and “Condition Assessments Based on Changes to Prior Condition” may have contributed to not properly identifying the development of a serious failure mechanism."

Jan 1, 2017

By Gianni O. Chieruzzi

A 400 MW, gas-fed power plant on floating piles and piled raft foundations was constructed in the Province of Moskovskaya, Russia in 2008. The subsurface is characterized by fill underlain by loose to medium dense alluvial deposits, with peat and clay interbeds, a stiff to hard, highly plastic, silty clay stratum of glacial origin, and a stratum of very dense, varved interbeds of sand and silt. More than 800, drilled concrete piles were constructed at the site. The pile length ranged from 15 to 23 meters below existing surface grade, and the pile diameter ranged from 0.9 to 1 meter. Initial analyses by others predicted total power plant settlements of 3 to 4 cm when subjected to the permanent loading conditions. Under a peer review process for the equipment supplier, subsurface investigation and testing were performed to verify the consolidation parameters used for foundation design of the power plant foundation. The parameters obtained in this investigation were used in the 3-D finite-element model ELPLA as inputs for the settlement analysis of the turbine building and power island. The ELPA analyses predicted settlements on the order of 7 cm over a period of 30 years. The actual settlements after two years of monitoring were compared against the model predictions. The rate of settlement and the recompression index were both underestimated in our model. The measured settlements have enabled us to calibrate both of these model parameters so that the model better matches the data.

By Alireza Ayoubian, Douglas S. Roy, Gianni O. Chieruzzi

"A 400 MW, gas-fed power plant on floating piles and piled raft foundations was constructed in the Province of Moskovskaya, Russia in 2008. The subsurface is characterized by fill underlain by loose to medium dense alluvial deposits, with peat and clay interbeds, a stiff to hard, highly plastic, silty clay stratum of glacial origin, and a stratum of very dense, varved interbeds of sand and silt.More than 800, drilled concrete piles were constructed at the site. The pile length ranged from 15 to 23 meters below existing surface grade, and the pile diameter ranged from 0.9 to 1 meter.Initial analyses by others predicted total power plant settlements of 3 to 4 cm when subjected to the permanent loading conditions. Under a peer review process for the equipment supplier, subsurface investigation and testing were performed to verify the consolidation parameters used for foundation design of the power plant foundation. The parameters obtained in this investigation were used in the 3-D finite-element model ELPLA as inputs for the settlement analysis of the turbine building and power island. The ELPA analyses predicted settlements on the order of 7 cm over a period of 30 years. The actual settlements after two years of monitoring were compared against the model predictions. The rate of settlement and the recompression index were both underestimated in our model. The measured settlements have enabled us to calibrate both of these model parameters so that the model better matches the data.IntroductionA 400 MW, gas-fed power plant was constructed near Moscow in the Province of Moskovskaya in Russia.Figure 1 shows the general arrangement of the main structures, and the geometry of the piles supporting those structures."

Jan 1, 2017

By Daniel W. Mageau, Larry W. Applegate, Aaron K. McCain

"An innovative method of ground freezing was successfully tested to create a “dry” excavation condition for a new building foundation at a site in downtown, Miami, Florida. The subsurface conditions in Miami generally consist of very porous, weak limestone and sand with groundwater near the surface. Water flow through these materials can be very high. Dewatering is extremely restricted in Miami so deep below-grade structures are rare and expensive. A new, innovative method to allow deep excavations in dry conditions without dewatering involves the creation of a thick, temporary, frozen soil plug below the planned excavation depth across the entire site to cut off vertical groundwater flow during construction. Frozen soil is impermeable and very strong and has long been used for temporary structural and water-tight shored walls. Using the same proven principals, frozen soil plugs are very effective at cutting off water from the bottom of the excavation as well as resisting upward buoyant forces. This new freezing method can be used for fairly deep excavations in new building construction supported on deep foundations. The building piles act as temporary anchors for the frozen plug to resist very high upward buoyant pressures until the permanent structural slab is completed.IntroductionUnlike other Cities, below grade basements are rare in Miami. The few basement foundations constructed have utilized a cumbersome and expensive method of excavation and shoring involving underwater excavation, tremie slabs, and commercial divers. The key issue for underground construction in this area of the country is the vertical flow of groundwater through the base of the excavation. To deal with this issue in the past, the contractor first installed all of the building piles and the perimeter shoring walls. Then, interior sheet pile walls are installed to create small manageable excavation pits. Each pit is then excavated through standing water “in-the-blind” and around the buildings support piles. The final excavation, interior struts, and inspection is performed by commercial divers. Finally a thick foundation tremie slab is poured under water. This method could be successful but proved to be time consuming and expensive. In addition, some building piles were occasionally damaged during the under-water construction process."

Jan 1, 2015

By Todd W. Armstrong, Michael D. Reader

"INTRODUCTIONThe Playa Vista Development is the largest urban infill development in the history of the United States. Overall, it encompasses about 1100 acres in the City of Los Angeles and is situated north of Los Angeles International Airport near the Pacific Ocean. The development taking place on the project consists primarily of high-density residential condominiums with 1 to 2 levels of subterranean parking . The geotechnical conditions are typified by high groundwater, soft clays, and liquefaction, in addition to environmental issues such as methane.Due to a combination of the geotechnical factors and noise restrictions, both driven and drilled piles were not feasible once the initial phase of the project was occupied. As a result, the project developer undertook a testing program that consisted of the installation and load testing of 9 piles in order to obtain City of Los Angeles acceptance of a pile installation system that met the site constraints. The testing program was divided between two separate contractors operating on sites set on opposite sides on the street (Figure 1 ). Contractors working in Test Areas A & B employed the ""dry dip"" and ""wet dip"" methods of auger pressure grouted displacement (APGD) pile installation, respectively.This paper summarizes the extraordinary program undertaken to install, document, test, and examine auger pressure grouted displacement piles at this site. The program ultimately resulted in City acceptance of auger pressure grouted displacement piles, a historically difficult challenge given the City's resistance of acceptance of ""new"" technologies.A summary of elements included in the test program are: (1) quality control; (2) load testing; (3) long-term testing; (4) non-destructive testing; and (5) pile exhumation."

Jan 1, 2005

By James S. Graham

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

Jan 1, 2005

By George Piscsalko

"Quality control of drilled shafts and ACIP piles is greatly dependent upon the practices of the site personnel. In many applications it is difficult to properly inspect the shaft prior to concreting, such as when the shaft is drilled under slurry. In other cases, such as ACIP piles, it is impossible to inspect the shaft in any manner prior to concreting. There are numerous methods currently available to assess the integrity of drilled shafts and ACIP piles. Each method has its advantages and limitations. This paper will compare the various available methods as well as introduce a new method for assessing integrity in drilled shafts and ACIP piles. This new method, known as Thermal Integrity Profiling, determines the integrity over 100% of the shaft both inside and outside the reinforcing cage by measuring the hydration temperature of the concrete along the length of the shaft. These temperature measurements can be made by either passing a thermal probe through a standard Cross Hole access tube typically 12 to 48 hours after concrete placement, or from embedding thermal wires within the shaft prior to concrete placement and monitoring them with unattended data collectors for 12 to 48 hours after concrete placement. This Thermal Integrity Profile method will be described in detail and several case histories will be presented. Additional testing methods which will be compared include low strain Pile Integrity Testing, and Cross Hole Sonic Logging. Advantages and limitations for each method will be discussed.IntroductionDrilled shafts and Augered Cast-in-Place (ACIP) piles have been increasingly used over the past several years due to several reasons including the reduced noise and vibration, speed of installation for ACIP piles, and the large axial and lateral capacities which are attainable for very large drilled shafts. ACIP piles are drilled and cast without any visual inspection. Drilled shafts can be cast in a dry hole which allows for inspection of the hole prior to casting, but the casting process is very difficult to nearly impossible to inspect with any accuracy. Drilled shafts are frequently cast under slurry as a means to stabilize the surrounding soils during the construction process. When casting a drilled shaft under slurry, it is very difficult to accurately inspect the hole prior to casting and it is equally difficult to inspect the shaft during the casting process. Many of the above mentioned processes are blind to inspection and therefore the chances increase for having defects present in the completed elements."

Jan 1, 2017

By Meeok Kim, Thornton Tomasetti, Seth Knihtila, Michael Oakland, Shawn Leary

The transformation of Seattle's historic KeyArena into the state-of-the-art Climate Pledge Arena, home to the NHL's Seattle Kraken, was no small feat. The $930-million renovation and expansion required the near-total demolition of the old structure and construction of an 800,000 sqf (74,000 m2), below grade venue while keeping its landmarked façade and roof intact. To do that, the project team had to come up with solutions for excavating 680,000 cu yd (520,000 m3) of soil to make way for the new 17,000-seat arena while working around the massive temporary shoring supporting the 44 million lb (20 million kg) roof all in time for the NHL's 2021-22 season.

Sep 1, 2023

By Takefumi Takuma, Hiroyuki Nishimura, Shigeru Kambe

"In order to achieve tubular pile driving with low noise and low vibration, the Press-in Piling Method has been adopted on many projects. The method utilizes reaction force derived primarily from previously driven piles to push in the next pile into ground. With attachments, the Press-in piling equipment can deal with hard soil as well as difficult site conditions. At West Toronto Diamond Rail Grade Separation Project in Toronto, Canada, the Press-in piling equipment drove more than 500 of 914 mm (36 inches) diameter tube piles in length of 12 to 25 meters (39 to 82 feet) to construct earth-retaining walls for railway grade separation. Myoshoji River Restoration Project in Tokyo, Japan drove some 600 of 1,000mm (39.4 inches) diameter tube pipe sections in length of 11 to 22 meters (36 to 72 feet) by the rotary Press-in piling equipment to increase the flood drainage capacity of an existing river in highly populated area of the city. Both projects exemplify the advantages of the method in urban settings.1. BACKGROUNDThe Press-in Piling Method was invented some forty years ago in Japan, where a very large number of construction projects were causing widespread construction pollution, especially by pile driving work in densely populated areas. The method has been providing solutions for piling projects which could not have been built otherwise due to the noise and vibration impact to the surrounding communities. The method can be used with various types of piles including sheet piles, tubular piles, concrete sheet piles and so on. With high pressure water jet and continuous flight auger attachments, the Press-in piling equipment can deal with dense sand, stiff clay, gravels, boulders and even soft rock without employing a different set of equipment."

Jan 1, 2015

By Lois G. Schwarz

I did not make studies about this parameter but I can say that some researchers recommend using low C3A cements to repair masonry mortar in order to reduce a possible combination with sulphate that can be present in old mortars.

Feb 10, 2003

By I. D. Dayal, Anil Kumar Jain

"Cutoff walls are frequently used to slow down or prevent seepage of water through and/or around dams. Cutoff wall is a type of seepage barrier structure designed to reduce the flow of water underneath temporary or main dam. There are number of techniques for the construction of cutoff walls including concrete, Jet grouting and permeation grouting. NHPC LTD, a premier Govt. of India undertaking has been instrumental in the hydropower development within the country & in nearby countries like Nepal & Bhutan since last four decades. NHPC LTD has completed more than 20 hydro-electric projects with total installed capacity of 6587MW (including capacity addition by JV- NHDC). In all these projects, different types of dams and spillways were constructed in not so benign to extreme challenging geological set up. There has always been challenge associated with the temporary diversion works. The project sites sometimes incur huge river bed excavations in case of concrete gravity dam founded on rock foundation at large depth. The challenges for minimizing the seepage have been well taken care by constructing the dedicated seepage barriers. The construction of cut-off walls have progressed from “conventional continuous trench backfilled with conventional concrete or plastic concrete” to “grout curtain”, to “jet grouting” to the “concrete cut-off wall” , the last being the most sophisticated & credible seepage barrier.The efficiency of the cut-off walls are monitored by the seepage quantity observed (reduction of the seepage flow), uplift pressures or exit gradients after construction of cut-off walls. For construction of the main concrete dam, required space is created by the river bed excavation for placing the dam foundation on sound rock. Sometimes there is deep river bed excavation from 30 to 40 m depth or even more as per the available rock profile. Temporary coffer dams are constructed for diverting the river flow through diversion tunnels / channels etc. In deep river bed excavation; there are high chances of the significant seepage through the coffer dam foundation / river bed material due to high hydraulic gradients. Seepage and piping are the main causes of the failure / damage of the temporary coffer dams. If the seepage quantity is too high, then it becomes difficult to handle it by dewatering in the dam pit. Dam concrete is required to be placed unhindered to have a monolithic construction of dam blocks & to have faster construction in the working season. Cut-off walls increase the seepage path considerably thus reducing the exit gradient and further reduction of the seepage thus helping in maintaining the seepage free area for working."

Jan 1, 2016

By Hennie F. T. Barnard

Where geotechnical designs are governed by settlement requirements, soil and rock moduli are important parameters for design. This paper reports on a method that was used to utilize dynamic modulus measurements in the field toward pile settlement designs for the proposed Square Kilometer Array (SKA) Project to be located near Carnarvon, South Africa. The project will comprise of over 3000 No. movement sensitive satellite dish structures. The method described in the paper utilizes strain-related modulus degradation across the complete ground profile, starting from measurements of peak particle velocity (and inference to dynamic modulus at small strain) as measured using Continuous Surface Wave (CSW) testing at individual dish positions. This is required due to the very small allowable foundation rotation of 5 arc seconds under the dishes? operational conditions. The strategy of analysis was to conduct an iterative process starting from the measured small strain modulus profile of the ground. The likely maximum pile force for a specific piled foundation option was estimated and a single pile finite element analysis was performed using Plaxis 2D (Version 2010) to estimate the expected ground strain developing along the length of the pile. By assuming the shape of the shear modulus degradation curve with increasing shear strain, the iteration process then converged on a likely degraded modulus profile associated with the single pile and maximum load assumed. This process enabled identifying the pile cap size, pile configuration, pile sizes and pile lengths that would meet the operational movement limits. The chosen pile group configuration was then analyzed using the Repute 1.5 pile group analysis software. The design process and typical results are discussed in this paper.