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By Yazen Khasawneh, Yao Zhang

Upgrading and maintenance programs were proposed at a power generating plant in Indiana. To perform construction activities associated with the proposed upgrading and maintenance, a LR11350 crawler crane with a dead load of 1,500 ton was required in the vicinity of existing plant structures. The contact pressure from the crane tracks for the heaviest lift, maximum reach and angle (worst loading condition) were estimated by the rigging engineer to be on the order of 84 psi. Several concerns were raised regarding the total and differential settlements while the crane is in operation and the induced stresses on existing underground utilities due to crane loads. Three-dimensional finite element simulations were conducted using hardening soil model for the subsurface soils and elastic model for the other structural elements (underground utilities and crane mats) to optimize the configuration of the proposed crane foundation. It was found 1-foot thick engineered steel mats underlain by a 1.5-foot thick crushed stone pad will provide enough support to the crane. It will also control the settlement to the allowable limit and maintain the stresses in the underground utilities within tolerance. INTRODUCTION A LR11350 heavy lift crawler crane was proposed as part of an upgrade program at an existing power plant in the state of Indiana. The proposed crane will be sitting on an open ground in the vicinity of existing plant facilities, with multiple underground utilities going beneath the proposed footprint of the new crane pad. The existing utilities are of diverse kinds, including sanitary sewer corrugated metal pipes, electrical conduits and variable steel water/oil drain pipes. The safety and functionality of these underground utilities are critical to maintain the proper operation of the power plant. Therefore, the design of the new crane pad foundation system is of essential to control the ground settlement and the imposed stresses to the existing utilities (Davie et al., 1998, Scott 2017). To ensure all utility locations and depths are identified, the proposed footprint was thoroughly surveyed. Information in regard to each identified utility was provided by the owner. Subsurface explorations were conducted using geotechnical soil borings and soundings to evaluate the ground conditions and generate soil profiles. Numerical simulation and analysis utilizing finite element method were performed to design the crane pad foundation system and evaluate the responses of the utilities. This paper summarizes project information, geotechnical conditions and then focuses on the finite element analysis in assisting the design of crane pad and the utilities evaluation.

Jan 1, 2019

By Sarah Ramp, Daniel V. Cacciola, Justin Labrozzi, Shafiq I. Siddiqui, Faisal Ahmed

"Construction of embankments up to 34 ft in height for twelve ramps and roadways needed for the New Jersey Turnpike Interchange 14A project required ground improvement. The subsurface conditions, consisting of up to 30-ft thick layer of highly-compressible peat and organic soils, would induce up to 8 ft of primary and 4 in. of secondary consolidation settlements to the embankments over a long period of time. Innovative ground improvement solutions were needed to meet unique challenges posed by the poor subsurface conditions, space and existing utility constraints, aggressive construction schedule, and massive size of the project. A variety of ground improvement techniques were utilized in six different zones of the embankments to limit settlements and ensure stability of the embankments. These techniques included preloading with surcharge and prefabricated vertical drains (PVD), load balancing using light weight fill, and concrete column rigid inclusions (RI). Additionally, augercast piles with load transfer platform were used under an existing bridge with low vertical clearance. An innovative approach consisting of preloading with surcharge and PVDs followed by installation of RI was needed in one of the six embankment zones with the worst, i.e., very soft, soil conditions. The design of the RI was performed by a specialty ground improvement contractor (SGIC) using Plaxis 2D and 3D softwares. The performance of the ground improvement systems was verified and monitored by load tests and instrumentations. This paper presents details of the ground improvement design, construction, monitoring results, and lessons learned, with a focus on the RI.INTRODUCTIONNew Jersey Turnpike Interchange 14A is located within the cities of Bayonne and Jersey City, in Hudson County, New Jersey. The New Jersey Turnpike Authority (NJTA) identified Interchange 14A as an area of mass congestion in need of redevelopment to improve the increasing demand of traffic and roadway safety. The New Jersey Turnpike Interchange 14A project included the construction of twelve (12) new roadways, in addition to the construction of four new bridges. The limits of construction are shown in Fig. 1.The fill height required to construct the roadway embankments varied from 2 to 34 ft. The proposed embankment side slopes varied from 6H: 1V to 2H: 1V. Additionally, mechanically-stabilized-earth (MSE) walls were utilized to retain the embankment fill along some segments of the roadways. As shown in Table 1, the proposed roadways were divided into six zones, based on location, subsurface condition, and embankment height."

Jan 1, 2017

By Atta B. Yiadom, A. David Miller, Robert C. Kirby, Sean M. Todaro

"San Pablo Dam is a 170-foot (52-meter)-high earthfill embankment, located approximately 10 miles (16 kilometers) north of downtown Oakland, California, that impounds a 38,600 acre-feet (47.6 million m3) reservoir for customers in the East Bay Municipal Utility District's (EBMUD's) service area. Seismic upgrades were designed and constructed in 2008 through 2010. Work included removal of an existing 140,000 cubic-yard (107,000 m3) downstream buttress, which was replaced with an enlarged 300,000 cubic-yard (230,000 m3) buttress founded on alluvium and colluvium that were improved in-place using Cement Deep Soil Mixing (CDSM) technology. The site characterization for the project, design of CDSM, reuse of CDSM spoils as construction materials, and environmental permitting have been described in five previously published professional papers.This paper provides a brief summary of the design of the seismic upgrades and presents the results of measurements made during and/or after construction including the variation of CDSM strengths with time, piezometric levels within the dam and foundation soils, and seepage flow rates. These measured values are compared to the values estimated during design of the seismic upgrades.INTRODUCTIONSan Pablo Reservoir is located approximately 10 miles (16 kilometers) north of downtown Oakland, California, as shown in Fig 1. As many as 50 million gallons (200,000 m3) per day pass through the reservoir for treatment and distribution to a portion of the 1.3 million customers served by EBMUD. The dam is founded mainly on alluvium and was originally built in 1920 using materials excavated from the left and right abutments consisting of siltstone, claystone, fine-grained sandstone, mudstone, and shale that were excavated and placed using hydraulic fill methods. The dam is located within two miles (three kilometers) of the Hayward Fault which is capable of a moment magnitude 7.25 earthquake.Because of the foundation materials, construction method, and proximity to the Hayward Fault, the dam has undergone a series of seismic improvements, including the placement of a downstream compacted earth buttress in 1967 and an upstream compacted earth buttress in 1979. In 2002, the State of California Division of Safety of Dams (DSOD) requested that EBMUD evaluate the seismic stability of San Pablo Dam, following the results of a study that same year that indicated a 62 percent chance of a greater than 6.7 magnitude earthquake striking the San Francisco Bay region between 2003 and 2032. The dam was evaluated and it was concluded that portions of the underlying foundation soils may liquefy during the maximum credible earthquake which could cause the dam to become unstable."

Jan 1, 2015

By Zachary Q. Maassen

Upon approval from the Las Vegas Convention and Visitors Authority (LVCVA), Turner/Martin Harris, A Joint Venture began construction on the estimated $860 million expansion for the Las Vegas Convention Center District Plan. Totaling around 600 shafts (60 feet depth and 3-foot diameter), the foundation installation completed via uncased drilled shaft operation, spanned from October to December of 2018. During this installation, flowback water from the water table was encountered that contained various solids ranging from cobbles to clays to silts, as well as trace amounts of contaminants of concern (COCs) left behind as a result of previous business that used to occupy the same real estate as the current expansion; more specifically, Perchloroethylene (PCE), an organic chemical widely used as a solvent and degreaser. With over 2.5 million gallons of waste slurry to be treated, technologies were deployed to reclassify the waste from liquid to solid waste as well as recover and treat the water for reuse in land spraying applications. Utilizing these technologies, it is estimated that 1.2 million gallons of water was able to be reclaimed along with over 6,400 tons of solids; resulting in hundreds of thousands of dollars in cost and environmental savings. PROJECT OVERVIEW Amidst its famous attractions from gambling to world class entertainment, Las Vegas has long been highlighted as the “No. 1 trade show destination in North America for 24 consecutive years” (LVCVA, 2018). Each year, Las Vegas hosts approximately 22,000 meetings, conventions and trade shows, which support an estimated 65,000 jobs paying $2.7 billion in wages and salaries. In 2017, the Las Vegas Convention Center hosted 21 percent of convention attendees traveling to southern Nevada, which supported approximately 13,800 jobs, paying more than $576 million in wages and salaries. Including indirect and induced impacts, the Las Vegas Convention Center’s attendees generated $2.1 billion in economic impact for the local economy (LVCVA, 2018) . This substantial economic impact of course due in part to the attractions Las Vegas offers to its trade show attendees, along with Las Vegas’ easy accessibility to major metropolises along the West Coast and reasonable travel prices offered if coming in from the East, allows for a very attractive venue. And while being a famous destination is great for business, the city wants to further distinguish itself by offering the best venue as well. For this reason, the Las Vegas Convention and Visitors Authority (LVCVA) approved a three-phase expansion plan for the Las Vegas Convention Center District totaling well over a billion dollars, slated for completion by 2023.

Jan 1, 2019

By Leong, William. Chong, Kam Weng

Deep Vibro Techniques namely Vibro Compaction (VC) and Vibro Replacement (VR) are widely used in ground improvement to densify sands and strengthen cohesive soils. This paper describes the application of these techniques for the construction of 20 Ha Iron Ore Stockpile Yard with the maximum stockpile height of 14 m in Quang Ngai, Vietnam. The challenges of this project are to limit the stockpile allowable settlement and the surrounding pile’s lateral movement. The soil condition can be summarized as 12m – 18m thick of loose to medium dense SAND with qc around 5-18MPa and followed by 2.0 – 6.0 m thick soft clay with qc around 0.4 – 0.8MPa. Localized very dense sand layer was found. VR using stone columns were installed in soft clay layer while VC was adopted to densify sand layer. Additional shallow stone columns were built in sand strata to minimize pile top lateral movement. The post construction performance was verified by a large 6 m by 12 m plate load test (PLT). The predicted PLT deformation using Priebe’s improved properties for the VR will be presented and compared with the measured plate load test results.

Nov 1, 2022

By Srijit Bandyopadhyay, Aniruddha Sengupta, G. R. Reddy, Raj Banerjee

The objective of the present endeavor is to compare the performance of a pile raft system in foundation sand subjected to lateral loads. To study the behavior of pile raft system in sand a laboratory test was conducted on small scale model foundation system. The raft and pile was modeled by square concrete foundation of 250 mm x 250 mm x 15 mm in length, breadth and thickness and 25mm diameter and 250mm long circular pile located at the center of the raft. The system was tested under static lateral loads of 6.25N, 12.5N, 18.75N and 25 N respectively resting on dry Kasai River sand. A vertical surcharge pressure of 1.5kPa (10 kg) was applied on top of the model raft for each case. The results of the model tests have been simulated by a general purpose 3-D finite element software and the model has been validated with experimental results. The moments of the pile obtained from the model tests and those predicted by the numerical analyses for all the lateral loads matches reasonably well. For matching the trend of bending moments obtained from experiments, validation with theoretical results have been done with the help of Matlock and Reese (1960) approach for a single value of lateral loading. Moreover, a parametric study has been conducted with 5mX5mX0.3m raft size with 0.5m diameter and 5 meter long pile with increasing number of piles namely 2, 5 and 9 respectively to study the response in terms of moment and lateral deformation under available earthquake loadings, like Loma Prieta (1989) and Darfield Christchurch (2010). Bending moments of piles and load deformation curves for lateral loading have been studied for each case in which it is observed that the bending moments of pile significantly reduces (around 4 times) as the number of pile is increased to two, but it decreases to a nearly constant value (it saturates) as the number of pile is increased to five and nine. Moreover, the lateral deformation of piled raft system drastically reduces (around 2.4 times) for two pile system, and it saturates to a constant value with five and nine pile system. All these results indicate the constancy of stiffness irrespective of the number of piles in the piled raft.

Jan 1, 2015

By David W. Martel, Tom George

"As part of the regional water authority review and upgrade of local dams a 35m x 5m x 3m wet soil mixed block was required for stabilisation of a dam wall toe in remote Victoria, Australia. Remote access, extremely poor roads and high mobilisation costs made more traditional CSM and deep mixing methods cost prohibitive. The dam required a redesign to raise the wall by 2.0m to increase water storage. Additionally, the dam required additional stabilisation to reduce the risk of liquefaction during an earthquake event. Soil testing indicated loose, cohesionless, high permeability soils to a depth of 3.0 to 3.5m across the toe of the wall. This resulted in high dam seepage through the toe of dam wall potentially causing the factor of safety during a seismic event to decrease to a dangerous level. A number of laboratory trials were completed to determine the mix ratio of cement required to improve the strength of the saturated, liquefiable soil.Wagstaff Piling was responsible for achieving the required soil/cement strength and mix depth on site. As the ground conditions were too soft for conventional soil mixing equipment, an excavator mounted Mitsui road header was modified to fit a 20 tonne excavator. A purpose built remote batching plant was set up on more stable ground approximately 200m from the wall and utilised for preparation of cement and water slurry for supply to the machine. As the ground was too soft to support the excavator, the progressively improved ground was used as the working platform. Both wet grab sampling and in situ testing was undertaken to determine the UCS of the improved soil. These results indicated several variations in the results due to size effects.1 INTRODUCTIONA small town in remote Victoria relies totally on its water supply from a small dam. The dam wall required stabilisation works by ground improvement as studies completed on the dam classified it as a high risk of failure under an earthquake event. In addition, the earth fill dam had high levels of seepage and poor control measures, requiring the dam to be upgraded to comply with all regulations.The relevant water authority engaged a contractor under a design and construct contract to complete the works. Wagstaff Piling was engaged as the Subcontractor to provide design and construction advice including the contract for the ground improvement works. Initial discussions involved CSM walls, cut-off walls and mass soil mixing solutions. However, due to the access restrictions for piling equipment, mass soiling mixing was the chosen method of ground improvement."

Jan 1, 2015

By Jeffrey M. Taylor, Arturo Ressi di Cervia

"Construction of the drilled shafts for the Brightman Street Bridge Replacement Project were not only challenging due to working over the water but were also challenged by changed soil conditions, concurrent work being performed by an adjacent contractor on the same project, environmental restrictions and severe winter conditions. A total of 36 x 8 foot (2.44m) diameter drilled shafts with 7.5 foot (2.31m) rock sockets were installed for the East and West bascule piers. This project also included Osterberg Cell load testing on two production drilled shafts at both the East and West bascule piers. The results from the load test program were used to fine tune the design of the drilled shaft rock sockets. From a constructability standpoint the reverse circulation drilling method with a pile top drill rig proved to be an excellent choice for drilling the overburden and rock sockets of the large diameter deep drilled shafts. INTRODUCTIONThe replacement Brightman Street Bridge spans the Taunton River between Fall River and Somerset in Massachusetts.The new crossing is located approximately 1500 feet (450m) upstream from the existing Brightman Street Bridge, which was built in 1908. The new mainline bridge includes nine spans totaling 1725 feet (525m). A bascule type moveable span will be located in the middle of the Taunton River and provide a 200 foot (61m) open channel centered about the 400 foot (122m) navigational channel. The bascule span, which has a span length of 409 feet (124.7m), will be a trunnion-type four leaf structure with a solid deck. A site plan is shown in Figure 1 Contract 3, which includes construction of the foundations for the East and West bascule piers, was bid on December 19, 2000 and was awarded to Modern Continental Construction Company (MCC) on January 24, 2001. MCC in turn awarded the subcontract for the installation of the drilled shafts to TREVIICOS Corporation, which started mobilizing in June of 2001.The scope of work for the drilled shafts of Contract 3 consisted in installing 18 drilled shafts in three rows on each side of the river to support the bascule piers located in the middle of the Taunton River.The foundation plan for the bascule span is shown in Figure 2."

Jan 1, 2004

By Johannes Labenski, Christian Moormann, Johannes Aschrafi

"Open steel pipe piles are used for various applications in costal engineering, port structures and increasingly important for offshore structures. During the installation of open steel pipe piles the formation of a plug has an influence on the installation process of the pile and also on the final bearing capacity. The formation of the plug depends on different factors, e.g. the pile diameter and the installation method. This paper starts with a structured overview about analytical methods (API, EAP-EAU, UWA-05, HKU-12, Modified API) to calculate the axial bearing capacity of open steel pipe piles. The numerical simulation of the installation process of open steel pipe piles has to fulfill high demands, i.e. to accurately represent the penetration of the pile inside the soil, the formation of the plug and also the stresses and strains during the installation. A numerical back analysis of a comprehensive field test, using the Coupled Eulerian-Lagrangian (CEL) method and a hypoplastic constitutive model for sand, reveals the stresses and displacements of the soil and of the piles. The analysis provides a comprehensive understanding of soilpile interaction.INTRODRUCTIONThe particular difficulty in the numerical simulation of plug formation, is that the effect of plugging inside open ended steel pipe piles has not been fully investigated. In scientific papers different approaches are documented to explain this phenomenon. Some are based on in-situ tests and others are based on numerical simulations. One of the challenges is to determine the end bearing capacity and shaft friction of the steel pipe pile. Different approaches have been developed over the years to determine them e.g. from Randolph et. al. (1991, 1994) and Paik et. al. (2003). Recent approaches are the ICP-05 Method (Jardine 2005), the UWA-05 Method (Lehane 2005) and the HKU-12 Method (Yu & Yang 2012a). A comparison of some methods can be found in Schneider et al. (2010). A plug inside an open steel pipe pile can be visualized as a spatial bracing of soil between the inner surfaces of the pile, cf. Lüking (2010).. However according to Lüking & Kempfert (2012) this bracing only exists for the height in the end of the pile equal to twice its diameter.To identify a plug inside a pile, there are different measurable parameters. One parameter is the development of stresses around the pile during and after its installation. Henke (2013) measured the inand outside horizontal stresses at the pile tip during the installation. The results showed higher stresses on the inside compared to the outside. To validate his measurements he performed a numerical back-analysis of the measured installation process and got matching results."

Jan 1, 2017

By Christian Leble, Dr. -Ing. Jakob Vogelsang, Dr. -Ing. Oksana Solt, Dipl. -Ing. Joachim Meier, Dr. -Ing. Wolfgang Orth

In the course of closing the gap between the Brandenburg Gate and Alexanderplatz, the Museum Island station was built by Implenia Construction GmbH. The tunneling for the platform hall took place on a length of about 106 m (347 ft) under the protection of a major ground freezing measure and crossed the Spree canal as well as the listed castle bridge. The approximately 20,000 m³ (4.54 E+06 US gal dry) frozen mass lay mainly in the Berlin sands. In order to ensure safe tunnelling and to protect the adjacent buildings, the planners had defined requirements for the mean freezing temperature and thickness of the frozen mass. For a reliable conclusion on the dimensions of the frozen mass, we used innovative temperature sensors as well as the new, web-based 3D measurement visualization and the associated site-specific evaluation software. The largely automated evaluation enabled a quick and reproducible determination of the temperature distribution in the frozen soil and its thickness in the relevant cross-sectional areas. The measurements were validated by thermal calculations using the Finite-Element-Method. Thus, an objective and clear assessment basis was available to ensure rapid coordination between stakeholders. The evaluations provide new insights into the temperature influences from tunneling, the application of shotcrete and the concreting of the inner shell. The newly implemented active thawing system is also an interesting innovation.

May 1, 2022

By Garland Likins, Gray Mullins, George Piscsalko

"Quality control of drilled shafts is greatly dependent upon the practices of the site personnel. For drilled shafts cast under slurry, inspection of the hole prior to concreting is very difficult or impossible. There are numerous non-destructive test (NDT) methods currently available to assess the integrity of drilled shafts. This paper will discuss the theory and use of an emerging NDT technology known as Thermal Integrity Profiling (TIP). The Thermal Integrity Profiling method measures the elevated concrete temperatures that occur during the hydration process. These temperature measurements are made along the length of the pile and can determine the integrity over 100% of the pile cross section, both inside and outside the reinforcing cage. With the known shaft volume information, TIP can evaluate the effective shaft radius at each measurement location. With the increased use of TIP on highway projects, there is a need to have standard criteria for shaft acceptance. Shaft acceptance criteria can be based upon thermal measurements and subsequent analysis of the data to determine the average shaft radius, local concrete cover, and cage alignment. With this additional information obtained via the thermal testing method, acceptance methods based upon concrete cover can be developed. In this paper the Thermal Integrity Profiling method will be described, results from a case history will be discussed, and an acceptance criteria based upon concrete cover will be proposed.INTRODUCTIONDrilled shafts are an attractive foundation element in many applications due to their large axial and lateral capacities. When drilled shafts are cast in a dry hole, it is possible to inspect the hole prior to casting, allowing for very basic level of quality control, although the shape of the completed element is still unknown without some form of post construction testing. When drilled shafts are installed where soil conditions are unstable, the shafts will often be cast under slurry to support the surrounding soils during the construction process. When casting a drilled shaft under slurry, it is very difficult to impossible to accurately and efficiently inspect the hole prior to casting concrete and it is equally difficult or impossible to inspect the shaft during the casting process"

Jan 1, 2016

By Thomas D. Humbert, Christopher J. Ramsey

Construction of a new underground parking structure in State College, Pennsylvania, is situated on a site constrained by limited ROW and required excavations ranging in depth from 25 ft to 40 ft. Additional complications included busy surface streets, an active intersection, and numerous underground utilities that could not be disrupted by construction activities. To combat these challenges, an innovative approach for earth retention was designed that combined multiple types of retention systems. The overall system included alternating sections of soil nail walls and a hybrid system of soldier pile walls (consisting of micropiles) that were partially restrained by a soil nail wall in the lower portions of the excavation. Further, due to the limited space within the property limits that inhibited the length of the permanent nails, the wall design team collaborated with the project designers to develop a solution such that the completed wall became an integral part of the final design/construction of the underground parking structure. INTRODUCTION HERE at State College is a mixed-use, high-rise building in State College, Pennsylvania. The 12-strory building has up to 3 levels of below-grade parking, with the above-grade levels consisting of residential and commercial/retail space. The existing property was a parking lot bound by the streets Calder Way to the north, Garner Street to the east, East Beaver Avenue to the south, and Heister Street to the west. The overall property sloped approximately 20 ft in elevation from southeast to northwest. Excavation for the below-grade levels extended 21 ft to 36 ft (6.4 m to 11 m) below street level. During design-development phases of the project, it became evident that due to subsurface conditions and right-of- way limitations, conventional construction techniques would not be feasible. The full perimeter of the excavation would require earth retention including the weak shale bedrock along the bottom of the excavation. The project developer (CA Ventures) and general contractor (Brinkmann) coordinated with the specialty contractor and wall design engineer to find a solution. At this time, Coastal Drilling East (specialty contractor) and Wood Environment & Infrastructure Solutions (wall design engineer) became involved. The project developer and general contractor were aware they needed an earth retention system, but given the many variables the project faced, a single, straightforward solution would not work in this application.

Jan 1, 2019

By Mario Mauro, Jeff Taylor, Carlos Morales

"In 2007 the US Army Corps of Engineers classified the Herbert Hoover Dike in Florida as a Dam Safety Action Classification (DSAC) 1 dam, and started the implementation of one of the largest dam rehabilitation projects in the nation. The construction of the cutoff wall is a key feature of this rehabilitation work to upgrade the dike to current dam safety criteria. The cutoff wall installation is currently being completed on Reach 1, which extends from Port Mayaca to Belle Glade, under a Multiple Task Order Contract based on performance specifications and stringent verification criteria.For the construction of the cutoff wall TREVIICOS selected the self-hardening slurry method. Since the cutoff wall is installed through a layer of highly variable limestone with Unconfined Compressive Strength (UCS) up to 14,000 psi, the excavation requires the use of the hydromill equipment. This is the first successful application of the hydromill technology with self-hardening slurry in a large scale project in the US. This paper presents the details of the method utilized, the quality control procedures, and the experience gained over seven miles of cutoff wall installed.INTRODUCTIONProject LocationThe Herbert Hoover Dike (HHD) system, around Lake Okeechobee in South Florida, consists of a series of levees, culverts and locks and is approximately 143 miles long (Figure 1).Lake Okeechobee is the second largest freshwater lake in the lower 48 states of the United States. The lake is the primary drinking water source for numerous communities around the lake and to millions of people living along the lower east coast. The lake is also a vital source of irrigation for the agricultural industry in the South Florida region.Lake Okeechobee is 33 miles wide from north to south and 30 miles wide from east to west and has a surface area of 730 square miles. The average water depth of the lake is 9 ft."

Jan 1, 2017

By Bernardo J. Jiménez Vega, Edy L. T. Montalvan

During the last phase of the Circunvalacion Norte project in San Jose, Costa Rica, preliminary designs for an underpass structure of over 16 km (10 miles) considered drilled shafts as an earth retaining system. Since the project’s execution was delayed and close to the deadline, it was necessary to optimize this structure, with the drilled shafts being the most critical aspect. The key element in order to obtain an improved design was characterizing the job site with a specific site study for seismic demand, and the use of advanced numerical modelling, considering soil-structure interaction. The site investigation comprised the CPT, PMT, MASW geophysical tests, deep exploration drilling, and triaxial compression tests. The terrain was modeled using an advanced constitutive model with hardening plasticity calibrated from the triaxial tests. Plaxis software was used to calibrate the seismic model for the terrain and for the dynamic analysis. Two conditions were considered for the retaining structure: free-head and fixed head. A parametric study with drilled shafts of 1.0 m (3.3 ft) and 1.2 m (3.9 ft) in diameter, and center-to-center spacing of 1.3 m (4.3 ft) and 3.0 m (9.8 ft) was conducted in order to obtain an optimized structure. For each condition of the drilled shaft wall, the computed deformations were compared for two spectrum designs: site-specific spectrum and seismic code generic spectrum. Finally, a dynamic analysis was performed to check the performance of the drilled shafts with optimized spacing using a control earthquake. Based upon seismic performance curves, the analysis showed the possibility of greater spacing for the drilled shafts compared to the original design, obtaining a 32% reduction in the total length of the drilled shafts in the project.

Oct 1, 2022

By Ben M. Lewis, Yogesh Prashar

"The East Bay Municipal Utility District (EBMUD) is a major water utility service providing water to over 1.3 million people in the eastern San Francisco Bay Area. EBMUD manages 28 dams at 5 terminal and 23 open-cut reservoirs within a 331-square-mile customer service area. As part of a 2012 update on EBMUD’s Infrastructure Rehabilitation Plan for Distribution Reservoirs, EBMUD has decided to replace Central Reservoir, a 152.8 milliongallon open cut reservoir, with optimally sized tanks. This paper presents the results of an analytical comparison of various foundation reinforcement solutions for the proposed tanks including: Cement Deep Soil Mixed (CDSM) columns, vibro stone columns, rammed aggregate piers, and lightweight cellular concrete fill. The computational program GeoMat (www.ensoftinc.com) was used to perform simplified soil structure interaction analyses. Settlement estimates were developed for each alternative with the proposed loading and compared to an allowable differential settlement criterion established at 0.3-inches over a 50 foot length. The authors wish to present the importance of considering mat and soil interaction along with various settlement mitigation methods considered for this challenging project.INTRODUCTIONProject BackgroundCentral Reservoir is an operational open-cut reservoir located north of the intersection of 25th Avenue and East 29th Street in Oakland, California. The reservoir is bound by 23rd Avenue to the west, Sheffield Avenue to the east and Interstate Highway 580 to the north. Originally, the Central Reservoir site was a drainage swale incising into weathered bedrock formed from Pleistocene alluvial deposits. The reservoir was first constructed in 1910 by excavating a basin below grade and constructing an embankment dam on the south and cutting/filling the bedrock and alluvial deposits from the drainage swale. The main dam at the Central Reservoir site is also a DSOD (Department of Safety of Dams) jurisdictional dam and as such is regularly monitored by the EBMUD Materials Engineering Section and the California DSOD.In a 2012 update to EBMUD’s Infrastructure Rehabilitation Plan for Distribution Reservoirs, Central Reservoir was identified as a critical facility that has reached the end of its useful life and must be replaced due to: a failing panel craft lining which contains polychlorinated biphenyls in the interior coating, a roof that does not meet the current seismic code, and reduced operating levels due to potential leakage in the upper portions of the panel craft lining. Furthermore, Central Reservoir is about three times larger than required and is located at a lower elevation than other regional reservoirs in the pressure zone resulting in increased labor-intensive operational challenges and water quality operations.This project presents some challenging geotechnical demands – the site is founded on weakly consolidated Holocene Alluvium overlying weathered bedrock, the proposed structural loads are large, and the new Central Reservoir is to be placed on a pad at an elevation of 182 feet, required placement of up to 30 feet of fill over the current basin. Additionally, the project aims for a long-term foundation solution that will outlive the new replacement tanks and accommodate future site upgrades. In order to meet this goal, the differential settlement criterion for the tanks was ¼ inch over 50 feet length. Lastly, the project also aims to address EBMUD’s increasing trench spoil stockpiles by recycling discarded trench spoils as fill for the proposed tank pad."

Jan 1, 2016

By Dalia. R. Mohamed, Hisham H. Hafez, Marawan M. Shahien

"Construction activities in major projects that involve deep excavations necessitate the use of vertical walls surrounding the construction site to play an important role as earth retention system. The walls are usually partially penetrating impervious walls which can increase the efficiency of the ground water control system that usually consists of number of partially penetrating wells. The analysis and design of such system requires 3D numerical simulation. The aim of this study is to develop simplified semi-empirical approach to analyze and design such system. The analyzed model is a single well in a square site that is surrounded by impervious walls along the perimeter of the site in an unconfined aquifer. The results of the parametric analysis are presented in this paper aiming to assess and understand the factors that influence dewatering in terms of ground water or drawdown profile surrounding the well. The parametric analysis is carried out using the 3D finite difference software. The parametric analysis comprises with more than 550 cases calculated. The study involved the parameters; well penetration depth, impervious wall penetration depth, size of the construction pit, coefficient of permeability, well yield and well location or distance between well center to impervious wall edge.IntroductionThe presence of groundwater in a site may have impact on the construction processes involved during the course of project construction, especially those projects that involve deep excavations. Deep excavations, especially in urban areas, require the construction of supported walls all around the site perimeter to ensure the stability of the excavation. In most of cases, the constructed walls are relatively impervious. Depending on the ground and site conditions, the walls are not penetrating all the way down through to the bottom of the aquifer and thus the walls are partially penetrating walls. The presence of ground water necessitates the lowering of the groundwater to levels below the bottom of the excavation to ensure working in dry. This paper focuses on groundwater control systems that consist of deep wells inside square areas enclosed by impervious walls partially penetrating unconfined aquifers. The wells are partially penetrating the aquifer, as well. There are many factors or parameters that are related to the configurations of the components of the system that may influence the drawdown of a well in such groundwater control system. This paper is a part of a comprehensive study that aims to development of a simple method for estimating the drawdown of dewatering system of the described configuration. In order to achieve such a major goal, a 3D finite difference model is developed for the problem in hand. A comprehensive parametric analysis was then carried out to investigate the influence of all the parameters on the drawdown of a deep well in such groundwater control system. This paper describes the problem, the model, the parametric analysis including the involved parameters. The paper, then, demonstrate the results of the analysis showing the influence of the studied parameters on the drawdown of a single well."

Jan 1, 2016

By Kenneth R. Chadwick, Thomas J. Tuozzolo, Terence P. Holman

"Micropiles are often installed to retrofit existing foundations that experience distortion and to underpin structures prior to future construction. The Dublin Road Pump Station project is an example of retrofitting due to a basal failure during construction that compromised the bearing capacity of the soils. A completed pump station settled and had to be restored to its original position, and work could not proceed until a new support system for the partially completed wet well could be designed and installed. The project involved the construction of three below-grade structures for a new pump station in a growing area of Jackson Township, N.J. The general contractor constructed three pump station structures consisting of a pump chamber, wet well and an inlet chamber in early 2006.The geologic conditions beneath the project site (Figure 1) consisted of loose/soft to medium dense/stiff sand, silt and clay to a depth of 40 ft below ground surface, underlain by medium dense to dense glauconitic silty fi ne sand. When the general contractor was constructing the wet well, which involved an internally supported sheet pile excavation 32 ft below the ground surface and 28 ft below the static groundwater level, basal failure, boils and ground loss occurred. Driven piles were installed to support the wet well structure, but additional ground loss was observed within and outside the sheet pile excavation, followed by settlement of the adjacent pump chamber structure. Post-failure investigations were conducted by Mueser Rutledge Consulting Engineers, N.Y. (MRCE), a geotechnical and foundation engineering consultant. Their investigation concluded that the ground losses around the pump station structures had compromised the supportive capabilities of the natural subsoils.The owner engaged Moretrench, a geotechnical specialty contractor, to work with MRCE to develop a constructible solution to support the pump station structures in general and to restore the pump chamber to its original position. Knowing that ground loss had already occurred as a function of the initial basal heave and subsequent pile driving, the team selected micropiles as the preferred foundation element, primarily due to their flexibility in bypassing these disturbed zones and generating capacity as a function of grouting volume and pressure. Drilled piles were also recommended due to concerns about causing additional settlement of the pump chamber if driven piles were used."

Jan 1, 2008

By George Moses K, Mahendran K

Grouting is performed in rock masses in order to increase its strength properties and also to reduce the seepage. In the design of underground structures such as tunnels or caverns located in weak rock masses, grouting plays an essential role. Grouting is a complex process demanding high degree of skill and knowledge in understanding of grout flow and requirements for certain geological conditions. This paper discusses the design process for grouting in rock masses adopted for a cavern project and the practical difficulties faced during the execution at site. The design parameters of grouting includes the injection pressure, grout material properties and stopping criteria. The paper also discusses the various tests performed at site to evaluate the efficacy of the grouting process which was initially defined based on the design and previous experiences. The final grouting scheme suiting to the present geological condition is arrived based on the test results. The practical difficulties faced during the execution and the measures taken to overcome these are discussed in detail. This work shows the importance of state of art in the development of a grouting process based on geological and hydrogeological conditions prevailing at site and can be helpful in grouting design for weak rock masses.

Nov 1, 2022

By Chris Leach, Lucie Spencer

This case study describes the geotechnical aspects of the basement construction for a multi-storey, residential and hotel complex located in the newly developed Elizabeth Quay precinct in Perth, Western Australia. The development included a three-level basement for car parking covering the full site area which was constructed using the top-down construction sequence. Soil conditions generally comprised 2m of fill overlying medium to dense clayey sands that in turn were generally overlying a very stiff clay stratum at approximately 13m depth. Bedrock level was generally encountered at approximately 22m to 35m below ground level. The ground water table was at a depth of approximately 1m below the existing ground surface level. A site boundary basement wall was constructed using a diaphragm wall retention system. The majority of the vertical loads from the building were transferred to the Kings Park Formation (KPF) bedrock through the use of foundation piles constructed by the CFA method. The CFA piles were installed from existing ground level, resulting in approximately 9m sacrificial concrete length from pile platform level to basement 3 (B3) level. The permanent column loads are such that a single CFA pile was not structurally adequate. To allow a full CFA foundation system to be adopted, an innovative design and construction approach was developed for these heavily loaded columns. This paper discusses the site technical details and the design and construction aspects required to meet the challenges offered by this project.

Nov 1, 2022

By Tian Miaomiao, Cheng Yin, Shen Jun, Yu Hao, Li Yafei

Vast amounts of waste drilling mud containing heavy metals is produced during oil drilling process, which causes great pollution to the environment. Therefore, it needs to be treated until it is harmless. This study uses industrial waste and Portland Cement stabilized waste drilling mud; the unconfined compression strength, leaching amount of Pb2+ and Cr6+ ions, and pore size of the stabilized soil were tested at different times during freezing-thawing cycles. The antifreeze performance of the stabilized drilling mud with industrial waste is discussed. The results show that the strength of the stabilized soil decreases with an increase in the number of freeze–thaw cycles. The strength loss of the stabilized soil after freeze–thaw cycles can be effectively reduced by increasing the industrial waste content, especially the content of phosphogypsum in the stabilizer component. Pb2+ ions and Cr6+ ions can be effectively stabilized by industrial waste. The results of the pores test prove that the compactness of stabilized soil solidified by industrial waste residue is greater than that of cement alone.

Nov 1, 2022