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By Terzis D. PhD, Katterbach M.

While awareness around the environmental impact of existing grout materials and chemical binders is increasing rapidly, biotechnologies are growing traction as sustainable alternatives in groundwork operations. Herein we present the principles and application methods of bio-grouting. The term is used to describe a system which is based on soil, groundwater or marine enzymes which are able to catalyze the production of calcite replicating a natural phenomenon. The system’s end result are mineral crystalline bridges which act as binders to improve the geotechnical properties of soils. This paper presents a comprehensive description of bio-grouts, their underlaying mechanisms contributing to mineralization as well as environmental considerations. With their water-like rheology, bio-grouts have a wide application range and are minimally invasive, requiring only very limited injection pressures. The equipment is the same as that used in conventional cement grouting, and the reactant components are worldwide available or easily suppliable, which explains why bio-grouting has nowadays become a valuable and sustainable alternative towards efficient soil treatment. Recent developments in the last years have allowed to further increase the applicability and efficiency of bio-grouts to ultimately bridge the gap between research and practice. A case study is illustrated in this paper showing the successful implementation of bio-grout for the stabilization of weakly cemented sandstone to safeguard an adjacent road segment in Switzerland

May 1, 2022

By Samer Rabab’ah, John C. Niedzielski, Jason Valeria

The PHX Sky Train is an automated people mover system located at Phoenix Sky Harbor International Airport. Phase II of the PHX Sky Train includes the design of over 150 drilled shafts for support of four guideway abutments, 75 guideway piers and three proposed stations. The soil conditions in this area generally consist of alluvial Sand, Gravel and Cobbles (locally known as SGC) deposited by the nearby Salt River. The foundation system will support relatively high axial loads, lateral loads and moments due to the height of the elevated guideway above the ground surface, where it needs to pass over roadways, parking lots, an existing terminal, and other buildings. Deep foundation design involves designing drilled shafts within the SGC deposits, some of which extend below the long-term groundwater table. Such extreme design loading conditions, together with difficult ground conditions at the site, result in several challenges for the design and construction of the deep foundation system for the project. This paper will present the results of a drilled shaft load test program implemented to provide site-specific measurement of the axial and lateral performance of the project drilled shafts. The load testing program consisted of a bi-directional load cell axial load test and a lateral load test performed on an instrumented test shaft 84 inches in diameter. The development and execution of the load test program and analysis of the test results are discussed. Comparisons were developed between predicted load capacities of drilled shafts using different design methodologies and the load capacity measured from the load tests. The load test results showed that underestimation of the capacity is evident using conventional methodologies. The load testing program was important for verifying the performance of the drilled shaft foundations on the project and was used to reduce the size of the drilled shafts. INTRODUCTION The PHX Sky Train is a five-mile long automated people mover system situated at-grade and on an elevated guideway which connects terminals, parking facilities, a rental car center and the Valley Metro Light Rail system in Phoenix. The purpose of this automated train system is to provide a secondary transportation system within the airport to relieve roadway congestion, minimize wait times and travel times for passengers and provide climate-controlled waiting areas. Phase 1 opened to the public on April 8, 2013. Phase 1A opened on December 8, 2014.

Jan 1, 2019

By Alex Grenoble, Alex Reeb, George Filz, Farzad Abedzadeh

"This paper summarizes available information on the characteristics and properties of deep-mixed soilcement produced by the wet method. The topics covered in this paper include: unit weight, unconfined compressive strength, strength variability for field mixed materials, influence of curing time, influence of consolidation pressure, Young’s modulus, differences in strength and stiffness between small and large samples, creep deformations, Poisson’s ratio, and tensile strength. In addition, this paper discusses the development of design considerations and recommended property values for a project that uses soilcement to protect an existing dam penstock from loads applied by an overlying stability berm. Some of the key recommendations for the deep-mixed soil-cement to be used in this project are that (1) a curved strength envelope that includes tensile strength can be used in the analysis, (2) the stress-strain and strength properties can be characterized using Duncan and Chang's (1970) hyperbolic model, and (3) a specification based on the median unconfined compressive strength value is appropriate.INTRODUCTIONFor many projects, including foundation and embankment support, deep mixing can be designed based on simplified procedures and following standardized guidelines (e.g., FHWA 2013). However for unusually complex or critical projects, it is often necessary to perform numerical analyses, and in order to perform these numerical analyses well, a thorough understanding of the material properties is needed.This paper summarizes information on the characteristics and properties of deep-mixed soil-cement produced by the wet method, and it discusses the development of design considerations and recommended property values for a specific project, herein referred to as the penstock project, that requires numerical analyses. For the penstock project, a horseshoe-shaped enclosure of soil-cement is being considered beside and above an existing dam penstock to protect it from loads applied by an overlying stability berm that will be constructed for seismic remediation. The concept is to use soilcement created by the deep mixing method along the sides of the penstock and to use compacted soilcement above the deep mixing to create the crown of the protective soil-cement zone around the penstock. For this application, the soil-cement stiffness, rather than its strength, is the controlling design parameter. To achieve the necessary soil-cement stiffness, the strength will be high enough that the factor-of-safety values against instability along potential failure surfaces passing through the soil-cement are high. Following conventional practice, the soil-cement acceptance criteria will be based on the unconfined compressive strength, and the specified strength will be selected to produce the desired modulus value."

Jan 1, 2015

By Takashi Enomoto

"The cement deep mixing (CDM) method has a wide range of applications, both on land and at sea. This paper describes the features of the equipment on CDM vessels engaged in maritime construction in Japan: the DCM No. 3 barge, the DCM No. 6 barge, and the DCM No. 8 barge. The DCM No. 3 barge is a large vessel with a mixing area of 5.7 m2. The design of the elevator of the deep mixing unit on the DCM No.3 barge enables us to conduct deep underground/ sea operations. This enables us to conduct mixing at depths of up to 52.6 m below the seabed and up to 70.5 m from the water surface. Additionally, since the tower is installed on the center of the barge, it has excellent stability. The DCM No. 6 barge and DCM No. 8 barge are mid-sized vessels with a mixing area of 4.6 m2. The DCM No. 6 barge was fitted in 2013 with energy conservation equipment and upgraded to an environment-friendly CDM barge. The energy saving upgrade used electric power, instead of hydraulic power, by inverter controlled alternating current motor for both mixing unit and main hoisting winch. This enables the using on effective use of regenerative power when the deep mixing unit is lowered. A feature of the DCM No. 8 barge is that it has an inclinable tower located at the bow section for elevating the deep cement mixing unit. Since the tower can be greatly inclined, the hull has a lower center of gravity and greater stability when the vessel turns. This also allows the vessel to pass below bridges and simplifies cruise preparations, outfitting and dismantling work.INTRODUCTIONThe cement deep mixing method (CDM method) involves mixing and stirring a cement-based solidifier into soft ground to rapidly bring the ground to the desired firmness. This method is used to suppress ground shear deformation, increase strength, increase slip resistance, and mitigate liquefaction and subsidence. It has been recently used in Japan in the construction of revetments at controlled waste disposal sites, both to boost the strength of the seabed and to prevent the seepage of waste matter and other pollutants. Undertaking CDM construction work at sea requires specially constructed marine construction CDM vessels. Since CDM construction at sea entails many more restrictions on working conditions than construction on land, the vessels themselves sometimes need to be modified. This paper will describe 1) the remodeling of the turrets and mixing machinery for mixing to great depths in deep water (DCM No. 3 barge with eight axes); 2) the upgraded of equipment on board CDM vessels after accounting for environmental considerations (DCM No. 6 barge with four axes); and 3) the use of a inclinable tower (DCM No. 8 barge with four axes)."

Jan 1, 2015

By Michael G. Batten, Brian D. Keaney

]The Virginia Department of Transportation (VDOT) and the harbors on the James River routinely use precast concrete piles founded in the Yorktown formation to support bridges and other coastal structures. However, axial pile resistances for large diameter piles in this area have been historically overestimated on past projects. This may be due to a common assumption that very large unit end bearing resistance will be developed for a large diameter displacement pile that is driven a significant depth. This assumption is integrated in the Nordlund (1963; 1979) method which is commonly used to estimate axial pile resistance for bridge foundations. A static and dynamic pile load testing program was implemented as part of the Hampton Roads Bridge and Tunnel Expansion project in Norfolk, VA in the James River. A primary objective of this program was to calibrate an axial resistance calculation method against the measured load test results. A method developed by Eslami and Fellenius (1997) that uses CPTu data directly was effective at calibrating to the measured load test results, and allowed for clearer interpretation of the unit resistance values than indirect, semi-empirical methods that require interpretation of soil friction angle and undrained shear strength.

Sep 8, 2021

By David Miller

"The biggest concern about using soil mixing is the inability to observe physically the final product, which has led to a lack of confidence about what is in the ground. After all, you can’t see it and you can’t taste it and you can’t smell it, so are you sure it’s soil mixing? In addition, there are variations in techniques, tools and monitoring that have led to additional skepticism and the desire to “elevate” the product. This skepticism is why the industry is so scrutinized even when there are other technologies being used that do not experience nearly the same level of scrutiny. With other techniques, even with a slurry wall, you can see the backfill before it goes into the ground, and drilled piers have careful evaluation of the concrete mix even before placement into and verification of the open hole. Essentially, you get control over the final material. There is less control in soil mixing, and it’s very dependent on in-situ conditions. These factors make it difficult to rely solely upon installation parameters, quality control (QC) and verification tests. At some point, you may need to apply some engineering judgment.Start at the BeginningThe availability of sufficient and accurate geotechnical data (soil type, heterogeneity, shear strength parameters, variability, etc.) is important in establishing the material that will be drilled. This data will also help in determining the proper mix design to achieve the desired soil cement properties. Many factors must be considered when designing the mix and the mixing program, including any debris in the ground, different soil properties and varying moisture contents.Each of the various factors affect the final properties of the soil cement, so it really takes careful planning and evaluation of the mix design through iterations by looking at the soil types and adjusting the mixes. Clay is going to behave very differently than sand in both mixing efficiency and final properties. That is, the presence of clays results in more difficulty in achieving higher strengths and to physically mix the soil and the binder, whereas the presence of sands results in more difficulty controlling the final permeability."

Jan 1, 2017

By Vishal Pathak, Shailesh A. Godhuly

Ground Modification System in terms of Jet Grouting for soil strengthening and mass stabilization was engaged for a power plant project in an international power project, engineered by L&T-S&L. The site Geology consist of cohesionless type of sandy alluvial deposits (silty fine sand) as the main formation. Ground water table is encountered at shallow depth. Geological interpretation is done using soil investigation data along with CPT’s. This paper discusses design and implementation of jet grout technique to improve the mechanical behaviour of soil. To distribute load evenly from superstructure, a layer of growmast (drainage blanket) is laid above jet grout columns. Settlement evaluation is done using Finite element analysis with Plaxis 2D and Settle 3D. In the project, selected equipment foundations are resting on jet-grout columns including vibratory equipment like 144MW Gas Turbine etc. The project has been commissioned in September 2021 and operating with full capacity.

Sep 1, 2022

By Chandramohan P. V., Ravi Kishore

"An underground reservoir was to be constructed at Doha in Qatar. Simsima lime stone is present at the bottom. When the reservoir is empty, there will be uplift at the bottom but this will change to downward load when it is full. The rock at the bottom had high bearing capacity to resist downward load. But uplift had to be resisted by piles or anchors. The reservoir has a size of 120mx80m. Shrinkage and creep of concrete coupled with thermal contraction imposed a horizontal movement of 26mm on the extreme piles. So, piles have to accommodate this as well. This unique situation needed a unique solution. The solution was to provide piles with flexible high tensile strands to take tension. An annular space near the head of the pile would facilitate horizontal movement as well. Compression load was directly passed on to the raft bearing on rock.INTRODUCTIONAn underground reservoir for storage of drinking water was to be constructed at Doha, Qatar. The reservoir was proposed to have a plan size of 120m x 80m. Clear height inside the reservoir was proposed as 17.2m, from the bottom of roof to the top of bottom raft. Overall height of the reservoir at the outlet from the top of the roof to the bottom of raft was to be 21.2m. For the sake of inspection and in order to prevent pollution from the surroundings a gallery was planned around the reservoir. This could accommodate pipelines as well. This gallery was 3.0m wide on three sides and 8.4m wide on the outlet side.The gallery had removable gratings as cover in order to facilitate maintenance. Capacity of the reservoirwas proposed to be 40million gallons. The reservoir is divided into four compartments with baffle walls in each one for water circulation. Roof of the reservoir is kept at 300mm above ground level. There are two levels of car park on top of the reservoir. Top of the reservoir roof is at +14.35. Bottom varies from - 6.68 to -7.08. Lowest water table is at +6.00. Concrete structure of the reservoir was designed by a local consultant. The Navayuga Engineering Company was entrusted with the construction. Please see Figs 1 and 2."

Jan 1, 2017

By Babak Mamaqani

The Regional Connector Transit Corridor (RCC) is the Los Angeles Metro area's ambitious light rail project, running under the city's main thoroughfares, Flower and 2nd streets. When com- pleted, it will alleviate traffic and parking congestion downtown, while connecting thousands of residents living in the bedroom communities of Inland Empire and Long Beach to their jobs there. The rail line of 1.9 mi (3 km), which involves a $1.756 billion (€1.545 billion) budget to construct the under- ground rail line, including three new stations. They are the Grand Av Arts/Bunker Hill station at 2nd and Hope streets, Historic Broadway Station at 2nd Street and Broadway, and Little Tokyo/Arts District Station at 1st Street and Central Avenue, which will offer riders their first "one seat/one fare" ride option from Azuza to Long Beach. Regional Connector Constructors JV is led by Skanska USA Civil West California District Inc. (Skanska), in partnership with Traylor Bros., Inc. (Traylor), to deliver RCC to the Los Angeles County Metropolitan Trans- portation Authority (Metro). PB&A was the structural engineer of record (SEOR) responsible to design the shoring systems for the Grand Av Arts/Bunker Hill Station at 2nd and Hope streets, and Historic Broadway Station at 2nd Street and Broadway. The temporary shoring design for Historic Broadway Station is the focus of this article, and why the project received special recognition as a runner up for DFI's 2021 Outstanding Project Award. Two main challenges are discussed in particular: design of the shoring system considering all construction stages, and design of an underpinning system where the Los Angeles Times Building (Times Building) protruded into the station footprint.

Apr 1, 2022

By Andy Boeckmann

In early 2021, DFI formed a Foundation Reuse Task Force due to concurrent and coincidental discussions of this topic during meetings of the Subsurface Char- acterization for Deep Foundations and Testing and Evaluation committees. Interested members from both commit- tees, as well as of the Sustainability Com- mittee, joined forces to form the task force. The task force mission is to promote foundation reuse by leveraging experi- ence among DFI members and collabo- rating across pertinent committees. General goals of the task force are to identify, assess and reduce risks associated with reuse; to educate owners and decision-makers about reuse; and to improve the investigation, design, construction and testing practices associated with reuse. One of the first orders of business for the task force was to organize a roundtable discussion of foundation reuse for DFI's 46th Annual Conference on Deep Foundations in Las Vegas. Last fall's discussion was framed as a continuation of the successful "Horses for Courses" session of SuperPile '21, which also focused on foundation reuse. However, whereas the SuperPile session focused on technical content, the annual conference panel on October 13, 2021, was envisioned as a less technical conversation that emphasized audience participation while addressing approaches to decisions about foundation reuse issues. The roundtable consisted of five panelists: • • • Bryan Hartnagel, Ph.D., state bridge engineer, Missouri DOT (MODOT) Tom Bradley, project director, Stanhope, London Hilary Shields, senior geotechnical engineer, Arup, London Jim Mackey, vice president/chief marketing officer, McGee Group, London Susan White, attorney, Benesch, Cleveland The roundtable was moderated by Andy Boeckmann, Ph.D., P.E., a senior engineer who works in Dan Brown and Associates' Missouri and Illinois offices, and is an article co-author.

Feb 1, 2022

By Akhila Manne, Prasad P. V S R

Storage tanks are heavily loaded thin-shelled structures that exert large loads on and require large foundations to support them. They are generally very sensitive to foundation settlements as it may hinder the performance of tanks resulting in significant commercial or social impacts. Selection of their foundation is dependent on availability of suitable ground and limitations imposed by design specifications. Design of the tank foundations is generally based on theoretical methods and validation by representative field tests. This paper reviews settlement criteria for storage tanks as per national and international standards, case studies of large to medium diameter tanks supported on deep foundation i.e., bored cast-in-situ piles and shallow foundations on improved ground and their performance during load tests & hydro-tests is discussed. Paper concludes that storage tanks can also be supported on shallow foundations resting on improved ground reducing the settlement, time and cost significantly depending on the sub-soil.

Nov 1, 2022

By Alessandro Bertero, Manuel Toniolo, Vincenzo Tirozzi

"The installation of foundation elements (large-diameter Bored Piles or Diaphragm Walls) for the execution of underground works to be performed through the ""Top Down"" Technique (Stations, Car Parks, Subways, Artificial Tunnels) often requires the insertion, with pinpoint accuracy, of steel or prefabricated elements within the foundation system, to provide temporary and/or permanent support to the whole structure.The future high-speed railway station of Florence Belfiore (Italy) is a perfect example; the new station will be built in the Northwest area of Florence, about two kilometers far from the existing station of Santa Maria Novella. The project envisages installation of about 500 bored piles (1200-1500-2100 mm diameter), with lengths ranging between 50 and 70 m. In the upper inner part of 250 piles, a steel pipe (weight: 15-20 tons, length: 22-25 mt.) has to be inserted with pinpoint accuracy.The “TREVI-CALATORE” system allows to install the plunge columns and adjust their position and verticality.INTRODUCTIONThe execution of underground works via the ""Top Down"" technique, train or tube underground stations, parking shafts, tunnels, often implies the need to carefully insert steel or prefabricated structures, serving as provisional/definitive pillars, into the foundation elements.The future high-speed railway station of Florence Belfiore is a perfect example; the new station will be built in the Northwest area of Florence, located about two kilometers far from the existing station of Santa Maria Novella.The new Belfiore Station is part of the new European high-speed railway network. The works related to Florence urban penetration include (figure 1):•,a 6.5 km. twin tunnel excavated via TBM/EPB, that will run beneath Florence in a north-east direction,•,passing under more than 150 buildings, many of which can be considered historic buildings, with a soil•,coverage ranging from 6 m to 20 m;•,a North portal in Rifredi area, Firenze Castello Station;•,a South portal near Campo di Marte Station (which is also the launch shaft of the TBM)•,the new Underground Station in Belfiore area."

Jan 1, 2016

By Chris Harnan, Christophe Justino

The European Federation of Foundation Contractors (EFFC) and the Deep Foundations Institute (DFI) jointly published Edition 1 of the ‘EFFC/DFI Guide to Support Fluids for Deep Foundations’ in April 2019. This Guide was prepared by a Task Group comprising experts on deep foundations from contractors, materials suppliers, consultants and academics. The Guide builds on work carried out by the Tremie Concrete Guide Task Group and presented in Edition 2 of the Tremie Guide. The Paper discusses and describes the content of the Support Fluids Guide which presents the state of the art on support fluid management, as well as the R&D work currently being carried out and funded by EFFC and DFI sponsors through an ongoing Field Research Study (FRS) as well as a review of academic research linked to the EFFC/DFI joint effort aimed at improving knowledge and guidance on support fluids. The FRS and academic research will help to improve the understanding of relevant support fluid properties including stability of excavations, interface layer formation, effect of filter cake and the development of new sampling and testing methodology. The Paper also presents the initial findings from the FRS program as well as a discussion on the challenging aspects of support fluid management with emphasis on design, performance, testing, and the environment.

May 1, 2022

By Barritt Lovelace

Collins Engineers has been researching and implementing the use of drones on Civil Engineering Projects since 2015. Applications include bridge inspection, asset management, mapping, construction site management and emergency response. Recently this technology was used to map and model construction sites with deep foundations to verify and quantify designs. The ability to collect and use large amounts of data is transforming our world. Drone hardware and software is being used to capture and digitally replicate assets, giving owners unprecedented ability to visualize and manage their projects. Our teams help owners collect and process drone data into deliverables to be analyzed, annotated, stored, and shared. The use of drones can transform the way projects are managed and can improve project workflows. Data collected with drones can be processed into a digital twin of any project site or asset. This digital twin provides owners with a three-dimensional geometrically and geospatially accurate model. These models can be annotated and tagged with information that can be stored and shared locally or on cloud-based platforms. The data can be exported and used in a wide variety of CAD and GIS platforms. Goals When considering the use of UAS for several items need to be considered when establishing project goals. Safety Drones can be used to reduce job site safety risks in two ways. The first is that use of the drone can remove personnel from harm’s way. Surveyors and other project staff will traditionally walk the site to collect survey and other site information. These efforts can be replaced with the use of a drone eliminating much of the need for personnel to be on the job site itself which improves safety. The other way safety can be improved is that a digital model of a job site can be created on a daily or weekly basis that can be quickly analyzed for safety hazards. This analysis could be done remotely by safety officers to identify job site hazards which can then be corrected before injuries happen. Improved Deliverables Perhaps the most important reason to incorporate drones into project workflows it the ability to improve the project deliverables. Drones have the ability to quickly collect large amounts of high quality data which can be processed into orthomosaics, point clouds and 3D models that give engineers and project managers the information they need to make better decisions on design or project management.

Jan 1, 2019

By Stefan Schwank, Alexander Blatt, Franz-Werner Gerressen

Diaphragm wall technique is usually used to install diaphragm walls, which are known as underground structural elements commonly used for retention systems and permanent foundation elements as well as deep groundwater barriers, named Cut-Off-Walls (COW). In this exploration project, the diaphragm wall equipment was used in the 2019 summer season to perform the first part of an exploration and bulk sampling program for a potential mine on the Star Kimberlite. Beside the idea of using the diaphragm wall technique as bulk sampling equipment, the sampling program required the adaption of equipment and tools for a depth capability never reached before by a trench cutter in any commercial application worldwide. The paper will explain the development of the sampling program as well as the challenges occurred with the local geology and the specific demands of the exploration and sampling program. It will also provide an overview of the lessons learned during the 2019 season and will give an outlook to the approaches of optimization for the second phase which will be carried out in 2020.

By Takefumi Takuma, Tsunenobu Nozaki, Masashi Nagano

The city of Naruto in the southwestern part of Japan is situated at the mouth of the mighty Yoshino River. An approximately 1,000m-long levee/bulkhead along one of the river’s tributaries in the city was raised with prefabricated steel panel walls on a concrete base bulkhead. Some sections of the walls’ foundations were combi-walls made of sheet pile cut-off walls and interspaced pipe piles; both of which were installed with press-in piling because the new wall alignment was very close to existing homes and businesses. A Clamp Crane, which clamped onto already installed piles and moved forward and backward on them, was utilized for a segment where the access to its piling location was too tight for a conventional crane or a track-mounted pile driver to maneuver.

Sep 8, 2021

By Gisele R. Passalacqua, Taylor Malangone, Subhash Mahali

New York City is a busy metropolis with 8 million people. New York has the largest public transportation system with 6 million riders a day throughout the subway system. Keeping this infrastructure in service is vital to the overall economy of the region. Hurricane Sandy proved to have a devastating impact on infrastructure in Metropolitan New York. New York City Transit is on the forefront to provide resiliency and maintain its facilities with the use of flood protection systems. This paper presents flood protection structures utilized at Hammels Wye substation site in Far Rockaway, Queens, New York. The site is in close proximity and surrounded by water. The subsurface conditions consist of loose silts overlain by medium dense glacial sand. The high groundwater level combined with limited access to the site presented challenges. A flood protection system consisting of flood walls was recommended for this site. In certain areas the flood walls consisted of retaining walls supported on micropiles. For other areas, the flood walls consisted of steel sheet piles with jet grout columns to reduce seepage below the walls. The effect of driving sheet piles with vibratory hammers on nearby existing structures is always a concern. Recently, hydraulic hammers with variable moment/frequency are being considered as a mean to reduce vibration effects during driving. In this project, an instrumentation testing program was performed to measure peak particle velocity during sheet pile driving utilizing the variable moment vibratory hammer. Plots of peak particle velocity versus frequency were generated. This paper will present the design aspects of the flood walls and construction challenges during installation. This will prove beneficial to engineers in both design and construction fields.

Sep 8, 2021

By Daiki Takano, Naoki Takahashi, Hidenori Takahashi, Ikuo Towhata, Yoshiyuki Morikawa

"The method in this study, in which cement-treated piles are installed into the ground to decrease the amount of liquefied lateral flow, has been studied. The authors are also investigating the most effective arrangement of piles to optimize cost-effectiveness. In their investigation, they propose shifting the position of the piles to prevent lateral flow in various directions. The present study conducted centrifuge model tests to clarify the improvement effect of piles against the lateral flow of liquefied soil and the effect of the pile arrangement. Then, numerical fluid analyses were conducted to consider the improvement mechanism. As a result, the model tests and numerical analyses showed that the pile improvement dramatically reduced the lateral displacement and that the average total flow velocity decreased in the irregular case.INTRODUCTIONLiquefied ground subjected to seismic motion loses its stiffness and strength, and lateral flow often occurs in sloping areas and backfill areas behind collapsed quay walls. In the Hyogoken–Nanbu Earthquake in 1995, the reclaimed island that was surrounded by collapsed quay walls expanded toward the sea and the amount of displacement reached a few metres (Hamada et al., 1996). Two countermeasures can be considered to guard against lateral flow: preventing liquefaction and reducing lateral displacement. The former method is ideal; however it is costly and time-consuming. Based on these considerations, the authors (Takahashi et al., 2013; Morikawa et al., 2014) are currently studying a method in which cement-treated piles are installed into the ground (see Fig. 1) to decrease the amount of liquefied lateral flow. The countermeasure cost using this method is relatively low because of the low replacement ratio. The authors are also investigating the most effective arrangement of piles to optimize cost-effectiveness. It has been proposed that the position of the piles should be shifted so that lateral flow can be prevented in various directions, as described in Fig. 2."

Jan 1, 2015

"The Metropolitan St. Louis Sewer District (MSD) in Missouri, the country’s fourth largest sewer system, is upgrading its storm and wastewater infrastructure in a 23-yearlong, $4.7 billion initiative called “Project Clear.” Historically, during times of intense precipitation, the current sewer system becomes overwhelmed. The primary goals of this project are to improve water quality and to alleviate many wastewater concerns in the St. Louis region by planning, designing and building community rainscaping, system improvements and an ambitious program of maintenance and repair.Part of the system renovation has focused on constructing underground tunnels for storm water storage, permitting controlled drainage of runoff, and preventing overflows into rivers and streams. Construction plans for these storage tunnels called for eight vertical intake and ventilation shafts to be bored from the ground surface. These shafts will then be intercepted in the bedrock at a depth of about 150 ft (45.7 m) during the excavation of the 3,000 ft (915 m) long underground tunnel that will be about 28 ft (8.5 m) in diameter. According to John Deeken , a geotechnical engineer with Black & Veatch Corp. and construction manager for the Maline Creek project, the drilling and blasting technique for creating the shafts was ruled out because the project was located in a residential neighborhood. “We could have used rock coring or a cutter head, but the drop shaft for this project is constructed within 10 ft (3.05 m) of an existing 108 in (274 cm) diameter sewer main,” Deeken said. “We had to take precautions to avoid damage to it.”A primary planning mandate of all MSD Project Clear phases requires minimized impact on traffic and residents. The canister drilling method enabled work to be confined to the median of a residential boulevard running perpendicular to the side street without detouring traffic. In addition, canister drilling offered a highly-precise means to create the shafts, leaving a smooth-sided borehole, right on target. Ground conditions in this 132 in (3.35 m) diameter intake shaft were wet due to the high groundwater levels and close proximity to the Mississippi River. “They’ve been finding shale in 2 to 6 ft (0.6 to 1.8 m) layers between weathered layers of Mississippian limestone,” said Dan Spiecher, technician at Center Rock (CRI). “The 2 ft (0.6 m) layers we can punch through. The 6 ft (1.8 m) layers slow us down.”"

Jan 1, 2017

By Ali Nasirian Ph. D., Gabriel Carvajal

To facilitate the safer and more secure transportation of inmates from San Diego Central Jail to the new San Diego Courthouse, the County of San Diego committed to building a new transfer facility as part of the downtown developments. The transfer facility includes a three-story underground structure adjacent and connected to the Central Jail and a 60-ft deep, 23-ft diameter, 320-ft long tunnel. The tunnel starts at County Jail, passes underneath Western Regional Detention Facility (Old Jail) and, ultimately, connects to the State Courthouse. Condon-Johnson & Associates, Inc. (CJA) was selected to install the temporary shoring shaft for the underground structure as well as three arrays of canopy pipes to support the tunnel’s Sequential Excavation Method (SEM) construction. CJA installed the rectangular 56-ft deep access shaft shoring with three levels of bracing, and a combination of secant piles, soldier piles, and timber lagging. The shoring also included a sliding bridge at top to provide access for trucks to enter and exit from county jail during the duration of construction. Following shoring and shaft excavation, CJA installed and grouted 7-5/8” dia. canopy pipes in 3 reaches, parallel to the longitudinal design line of tunnel with a slight lookout angle. CJA installed 24 each canopy pipes, 99-ft from face of shaft at reach 1, 21 each, 80-ft length canopy pipes at reach 2, and 21 each, 75-ft length pipes at reach 3. CJA confirmed canopy pipe alignment via Inertial Sensing Gyro. To mitigate the possibility of settlements caused by the tunneling operation underneath Old Jail strip footing and grade beams, CJA also performed void fill grouting. Sleeve port grout pipes (SPGP’s) were installed inside the Old Jail basement and grouted with the use of packers as the tunneling operation passed underneath the Old Jail. In detailing various aspects of the construction, this paper aims to magnify the innovative solutions for shoring, canopy pipe installation and void fill grouting challenges as well as the state of the art quality control measures undertaken by CJA.

Oct 1, 2022