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By Anjana C. P, K. Ranga Swamy

The hilly regions of Kerala are severely affected by excess rainfall, causing tremendous damage due to landslides and slope failures. It is necessary to strengthen the existing slope profiles to prevent such disasters and avoid their risk to human lives and civil infrastructures. This paper studies the effect of micro pile to reinforce the slopes in Idukki district of Kerala, where slope failures are frequent. Three-dimensional slope stability analysis is carried out on slopes from the Idukki to obtain safety factor values using the MIDAS GTS NX program. The slope is fully saturated herein by taking the model's piezometric surface at the ground level to simulate high rainfall intensity. The critical slopes are then modelled with micro piles to analyze their effectiveness in improving the stability under static conditions. Different micro pile arrangements are considered, and a series of slope stability analyses have been carried out to obtain the optimum configuration with the required safety factor. The FOS values increased by more than 50% with micro piles for all the slopes. The optimum micro pile arrangement obtained for each slope shows that micro pile distribution between the toe and middle of the slope is an effective location for reinforcing slopes.

Sep 1, 2022

By Scott White, Pishun Tantivangphaisal, Andrew Bell, Chris Barker

There has been considerable advancement in recent years in the tools, both software and hardware, available to allow efficient digitalization of site records during the construction of geotechnical works. Whilst these tools have excelled at replacing handwritten records, the ability to use digital records to validate design and construction requirements in real time or even within reasonable timescales has generally been limited to the development of bespoke ‘prototype’ project specific solutions. This paper describes the development and implementation of an industry standard design schedule and the benefits of the broad adoption of a single database schema for data recorded on geotechnical sites. The former has brought significant improvements and automation of the design process, whilst the latter has enabled the validation of the constructed works against design intent in almost real time. Further details of the standardized design schedule, already publicly available in the UK through the FPS, examples and lessons learnt from implementing digital site record systems on live projects are presented herein. The utilization of cloud computing technology and complex algorithms linking plant/rig instrumentation with design data can further automate construction sites using IoT (Internet of Things) best practices. The authors will share their experience of the recent deployment of a digitalized design-to-construction record system, give recommendations for future development and a call for an industry wide drive to finalize and adopt the AGS Piling data schema.

May 1, 2022

By Sylvia S. Eskander, Sherif S. AbdelSalam, Mona B. Anwar

Expanded Polystyrene (EPS) geofoam has long been used in numerous geotechnical applications due to its lightweight and durability. Among these applications is the use of EPS as an alternative fill material to conventional roadway soil embankments. This study investigates the benefits of using EPS roadway embankments to reduce the induced stresses and strains on the underlying peat and soft clay. Firstly, mechanical and interface properties of the EPS were acquired from a companion study that also considered the cyclic loading and creep effects. In order to determine the actual stress-strain distribution within the EPS blocks, a physical prototype was developed in this study with overall dimensions of 1.2 x 1.0 x 0.5 m, with a density of 35 kg/m3. The prototype EPS blocks were subjected to cyclic loading with intensities ranging from 10 to 50 kN. Then, a numerical model was developed to simulate the behavior of EPS roadway embankments. The numerical model outcomes were verified against the prototype measurements. A parametric design study was also conducted to develop a correlation between EPS embankment height and the stress-strain that occur in the underlying strata. Results showed that EPS embankments could reduce stress and settlement in the underlying soil by about 40% and 54%, respectively. EPS APPLICATIONS AND BACKGROUND Expanded Polystyrene (EPS) geofoam blocks have been effectively used during the past several decades in numerous geotechnical applications. EPS static and dynamic properties as well as interface behavior were extensively characterized in various published studies such as that conducted by Horvath, 1994; Stark et al., 2004; Zarnani and Bathurst, 2008; Trandafir et al., 2010; Athanasopoulos et al., 2012; AbdelSalam and Azzam, 2016; and others. However, to be able to use locally produced EPS blocks, its physical and mechanical properties must be thoroughly determined. The lightweight and compressible material of EPS geofoam makes it suitable both as a backfill and for absorbing pressure in both the vertical and horizontal directions. Kim et al. (2010) adopted EPS as an alternative for soil backfill around buried pipes; their model showed a reduction in the vertical stress acting on the pipes by up to 36%. Oshati et al. (2012) presented a case study of a field-instrumented box culvert with EPS blocks on top, which reduced vertical stress by 58%. Meguid et al. (2017) used an EPS inclusion to surround culverts and achieved up to 72% stress reduction, depending on the EPS density and the culvert depth to width ratio. AbdelSalam et al. (2017) used a relatively thin EPS inclusion behind flexible cantilever retaining walls, verifying that the lateral pressure can be significantly reduced by 25%; they also developed a design chart for this application. Moreover, AbdelSalam et al. (2019) investigated the use of EPS as a lightweight alternative for soil backfill above shallow tunnels. It was found that EPS had created a differential movement between the wedge located above the tunnel and the neighboring soils, which accordingly reduced the vertical stress acting on the tunnel by 85%, due to the use of lightweight EPS material and positive soil arching.

Jan 1, 2019

By Chu E. Ho

This paper reviews the design of jet grouting at re-entrant corners of excavations where the diaphragm wall and secant pile wall installation were interrupted by existing utilities in the streel sidewalk. Jet grout blocks were formed to seal the gaps in the walls for excavation support, consisting of four to six columns in clusters. Jet grouting was performed around an electrical duct bank which had to be maintained. Jet grouting was executed through stratified soils using various combinations of jetting parameters for different soil strata. The installation sequence and age of the neighboring columns within a cluster will affect the jet’s ability to form subsequent columns. When jet cutting is limited next to hardened grout columns or embedded obstructions (such as diaphragm walls or secant pile walls in this case), the specific gravity (SG) of spoils would be reduced and tend toward the value of the injected grout SG. The magnitude of spoil SG is also influenced by the variability of the grout mix supplied. Specific Gravity Ratio (SGR) defined as the ratio of spoil SG to the actual grout SG at the time of jetting can be used as an indicator of successful treatment, with SGR > 1.0 indicating effective soil erosion. Verification coring and testing were implemented to confirm target column diameter and strength of grouted soils have been achieved.

May 1, 2022

By Stephen Buttling

The construction of a water treatment plant in Dandenong, Victoria, required detention tanks and a pumping well. The design provided by the Engineer used conventional rectangular cast-in-situ reinforced concrete walls within a sheet piled cofferdam. It was decided to construct the tank and shaft using the diaphragm walling technique as an alternative and, for the shaft in particular, this involved a “circular wall”. Except where cutters are used, joints in diaphragm walls have to be made between colinear panels, with waterproofing provided by dumb-bell water stops held within trapezoidal forms. This means that the circle has to be approximated by a number of straight sides, which in this case was twelve. The requirement was to design the reinforcement for the strange shaped panels. Finite element analysis was used, in the first stage using an axisymmetric model to determine the profile of lateral earth pressures with depth. In the second stage a horizontal slice was modelled, without gravity which normally operates from the top to the bottom of the page. By considering appropriate possible earth pressures at different depths, a range of bending moments was calculated, which was used by the structural engineers to design the rebar. The tanks were successfully constructed, and inclinometers were installed in both the tank and the shaft. Measured deflection profiles show that the design was moderately conservative.

Nov 1, 2022

By Braxton P. Erbe, Douglas C. Brunot

A variety of systems and techniques exist to support deep excavations where sloping is not feasible. This paper will explore an example project involving the use of pre-engineered hydraulic bracing systems to support sheet pile walls. Challenges on site that drove the final design include a high water table, irregular excavation geometry, and underground obstructions. The hydraulic system, connected by pins and not requiring welds, allowed for quick deployment and the modularity to change as required due to unforeseen site conditions.

By Shoji Higashi, Nobuhiro Honda, Takeo Asanuma, Tatsuo Nagatsu, Masaki Kitazume, Sachihiko Tokunaga, Shigeru Kubo, Hidenori Takahashi, Tsuneyasu Onishi, Yoshiyuki Morikawa

"Various kinds of civil engineering structures and facilities were seriously damaged in the earthquake in Tohoku and Kanto regions of Japan on 11 March 2011 due to the greatness of its magnitude. In contrast, many structures resisted the large seismic force having been reinforced by the CDM (Cement Deep Mixing) method, which is often used for increasing the bearing capacity of ground and improving seismic performance. This paper summarizes the field survey undertaken to investigate damage to structures and facilities reinforced by the CDM method. Several prefectures and metropolitan areas were selected for the survey, based on the occurrence of strong seismic motions. A total of 847 structures and facilities were studied, in the survey using a questionnaire, which mainly inquired about the appearance of structures and facilities. Of the respondents to the questionnaire, 789 replied that there were no seriously damaged structures. The paper presents the damaged and non-damaged sites of CDM-technique sites and non-CDM-techniques sites. It can be concluded from the field survey that the CDM Method demonstrates high efficacy and durability against a strong seismic motions.INTRODUCTIONDuring the afternoon of 11 March, 2011, a huge magnitude-9.0 Mw (Category 9.0 on the Richter scale) earthquake occurred about 25 kilometers below the Pacific Ocean’s surface off the coast of Tohoku. This massive earthquake, now called the 2011 Off the Pacific Coast of Tohoku Earthquake was the largest earthquake ever observed in Japan. The seismic intensity of this earthquake was measured 7, the maximum on the Japanese intensity scale, as observed 7 in northern Miyagi Prefecture. The earthquake caused severe damage over a wide area from Tohoku to Kanto, and triggered large tsunamis that struck the Pacific coast of Hokkaido, Tohoku, and Kanto. The number of missing and fatalities caused by this earthquake exceeded 18,000 persons, making this an unparalleled earthquake disaster with a cost-in-life toll not experienced by Japan in recent years. Because of the scale of its seismic motions, the earthquake damaged facilities and structures of many kinds. In the years prior to this earthquake, the CDM method was used extensively to increase the bearing capacity of the ground as an anti-seismic countermeasure and to prevent liquefaction. Immediately after the earthquake, the CDM Association visually surveyed the state of damage to about 800 facilities in the Tohoku and Kanto regions where a seismic intensity of 5 or higher was observed. This report summarizes the survey of damage to facilities and structures constructed applying the CDM method in order to confirm the durability and performance of the method against seismic motions."

Jan 1, 2015

By Dale Berner, Michael O’Sullivan

"This paper focuses on lessons learned from the innovative designs, in-the-wet construction methodology and modified foundation conditions, for two United States Army Corps of Engineers, USACE, Megaprojects:(a) The over $2 Billion Olmsted Dam across the Ohio River for the Louisville District; and(b) The $1.75 Billion Inner Harbor Navigation Canal, IHNC, Lake Borgne Hurricane Barrier in New Orleans for the Hurricane Protection Office, and the New Orleans District.Design innovations for the 24-inch dia. pipe pile foundation for the Olmsted Dam project include: (i) the use of controlled-fixity moment connections to the dam monoliths in order to tune the response of the dam under the 8.3 Richter scale seismic Maximum Credible Event, MCE; (ii) soil densification to inhibit liquefaction potential and (iii) design to facilitate underwater construction in a river with a highly moveable sand bed.Design innovations for 66-inch dia. concrete cylinder piles for the IHNC floodwall include: (i) the use of soil structure interaction, SSI, analyses to verify capacity to resist deep-seated failure plane in soft soil, while limiting lateral deflections to acceptable limits; (ii) the use of geo-fabric and scour stone for enhanced foundation response and (iii) design for ""in-the-wet"" construction on a fast-track basis.LESSONS LEARNED FROM THE INNOVATIVE OLMSTED DAM FOUNDATIONThe over $2Billion Olmsted Dam on the Ohio River is currently under construction 16 miles upstream from the confluence with the Mississippi River. It will consist of an 800-foot-long tainter gate section, a 1,400-foot navigable pass, two boat abutment sections, a fixed weir section, and upstream and downstream scour protection. The Olmsted Dam and its two, 1,200-foot locks, which were built in 2002, will eventually replace both Locks and Dam #52 and #53, both built in 1929, and thereby bring significant benefits to the Ohio River navigation system.In 2002, the Jacobs/COWI JV completed the design of the dam; which was an engineering challenge for several reasons, including:(a) Its proximity to the New Madrid Fault, could impose an 8.4 Richter Scale seismic event on the structure, which is located in an area of potentially liquefiable alluvium. The extensive seismic analysis performed by COWI included a response spectra analyses; lateral pushover analyses of pile foundations; hydrodynamic added masses; pile group effects; and the development of kinematic motions as a result of the soil-pile-structure interaction.(b) Maintaining vessel traffic along the river and accommodating fluctuating river elevations between 30-40 ft annually, and as much as 60 ft in a 100-year period.(c) Designing for the scour and uplift forces of artesian ground water and preserving a wildlife sanctuary on the Southern shore at the dam site."

Jan 1, 2017

By Camilo A. Alvarez, Stephen K. Harris, Brian R. Zuckerman, Philip J. Meymand, Danielle M. Steinmetz

"The sleek new air traffic control tower at the San Francisco International Airport stands at 221 feet tall and is set to replace the existing air traffic control tower by 2016. This aluminum-clad, torch-like structure and three-story Integrated Facilities Building at the base are situated between Terminal 1 and Terminal 2 adjacent to the tarmac. Berkel & Company Contractors, Inc. and Simpson Gumpertz & Heger Inc. worked in conjunction with structural engineers from Walter P. Moore Engineers and Consultants, geotechnical engineers from URS Corporation, architects from Fentress Architects, and general contractors from Hensel Phelps Construction Company on the performance-based design of a foundation to support this critical facility, which is located in a high seismic zone and situated on the very soft soil of the San Francisco Bay margin. With the loading demands and performance criteria established and Young Bay Mud thicknesses ranging from 44 to 47 feet thick across the site, the design team employed a total of 214 24-inch diameter Auger Pressure Grouted piles, which were drilled into the underlying Franciscan Formation as deep as 148 feet below existing grade. Pile reinforcement included full-length confined cages.The piles were designed to resist Maximum Considered Earthquake axial demands as high as 1,400 kips in compression and 700 kips in tension. The performance-based pile design included verification of shear capacity under double-plastic-hinge flexural mechanisms, verification of pile ductility via non-linear moment-curvature analyses, and consideration of curvatures due to kinematic as well as inertial loading.The team implemented an extensive pile load test program including a full-scale static compressive load test on a sacrificial test pile and five non-destructive high-strain dynamic load tests, four of which were performed on indicator piles that were later used as part of the foundation system. These piles were monitored with extensive embedded instrumentation throughout their length, including strain gauges and accelerometers."

Jan 1, 2017

By Pancho J. Garza, Keith H. Dahlen, Chris A. Labye

"Design for reconstruction of the East Flagstaff traffic interchange project located in Flagstaff, Arizona posed particular challenges. The proposed design included construction of a nearly 50-foot tall mechanically stabilized earth (MSE) wall given rightof- way constraints and soft subgrade soils. The tight right-of-way, approximately 15 feet in certain locations, adjacent to existing structures limited the number of viable remedial alternatives to provide grade separation at the proposed bridge abutment without significant settlement. Preliminary analyses indicated the existing subgrade soils - consisting primarily of relatively soft silts and clays with decomposed pumice - would settle approximately 12 to 14 inches resulting in unacceptable wall deformation. Stone columns placed via vibratory methods (vibro-replacement) consisting of circular excavations which penetrate to firm bearing soils and which are filled with crushed stone were selected to densify the existing subgrade soils. The implemented mitigation measures helped limit settlement to less than one inch and allow for successful construction of the project. The project history - including site constraints, subsurface conditions, evaluation of remedial alternatives, stone columns methodology, and effectiveness of ground improvements - will be discussed.IntroductionThis paper describes the subsurface investigation performed for the reconstruction of the Business Route 40 (B-40) (Country Club Drive) and United States (US) 89 Traffic Interchange (TI) located within the city limits of Flagstaff, Arizona. This project is currently referred to as the East Flagstaff TI. The Project Site Vicinity Map is shown below.The former B-40/US 89 TI was considered ineffective in handling the current and projected volumes of traffic which transition from northbound (NB) B-40 to US 89 (both directions), as well as from southbound (SB) US 89 to SB B-40. The intent of the project was to reconstruct the TI to better accommodate projected traffic volumes. The project eliminated the existing ramps from both NB B-40 to SB and NB US 89. The new interchange includes a Tee intersection from B-40 to US 89. In order to accommodate this alignment, the profile of US 89 was raised several feet (on nearly the same as existing horizontal alignment) to match the elevated profile of B-40. B-40 was shifted just west of its current alignment to accommodate construction of a new, wider bridge structure which spans over Industrial Drive, the Burlington Northern Santa Fe (BNSF) railway, and old Route 66. South of the new bridge, B-40 transitioned back to the existing alignment just north of the I-40/B-40 TI. Within the project limits, both US 89 and B-40 were widened to three travel lanes in each direction."

Jan 1, 2015

By Suthan Pooranampillai

Verification of drilled shaft resistance is primarily obtained through the use of different load testing methods. Procedures utilized include conventional top down static loading, the Osterberg load cell (O-cell) test and dynamic tests such as the Statnamic method. The O-cell test provides a means of obtaining separately the base and side shear resistance behavior of drilled shafts (cast-in-drilled-hole). Alternatively, the Statnamic load test method enables the engineer to derive base and side shear behavior separately, based on measurements of load, accelerations and strains along the length of the shaft. However, due to time and cost constraints these tests can only be performed on selected shafts within a project. Post grouting of a drilled shaft base embedded within a cohesionless material, with a low mobility compaction grout, will essentially pre-load the shaft base soil against the side shear and self-weight in much the same manner as an O-cell load test (when the load cell is placed within the base vicinity). Therefore, successful post grouting of a drilled shaft would enable verification of both shaft side shear and base resistance simultaneously on each and every shaft it is carried out on. Additionally, such post grouted shafts display stiffer load-displacement response during subsequent downward, superstructure induced, loading compared to ungrouted shafts. Verification of resistance on each and every shaft through the use of post grouting will allow an increase in resistance factors (reduction in safety factor) used in the design. Two 6 ft. diameter drilled shafts were constructed in Fredonia, WA, for WSDOT, each with an approximate length of 52 ft. The shafts were terminated within medium dense poorly graded silty sand. Statnamic load testing of the shafts indicated maximum derived static side shear and base resistances of 2545 kips and 507 kips (1.6 in. displacement) for shaft One and 2466 kips and 212 kips (1.4 in. displacement) for shaft Two. Shaft Two was subsequently grouted, with a low mobility compaction grout. Shaft base mounted total earth pressure cells measured a maximum sustained pressure of 55.44 ksf during the compaction grouting operation. Shaft displacement reached 0.65 inches in the upward direction at termination of grouting. Comparison of grouting data with initial load test information indicates that properly instrumented post grouting verifies shaft base and side shear resistance. In addition, these grouting induced resistances were much higher than design values supplied by the engineer using conventional resistance factor design. Large scale laboratory testing also shows that base grouting verifies higher soil resistances than permissible in conventional design.

Jan 1, 2010

By Abhijit Saha

"Two analytical closed-form elastic-rigid-plastic solution methods to predict the rigid foundation behaviour on stone-column reinforced soil are compared, both of which takes into account the stone material yield within the host soil according to stress-dilatancy theory. These are the mechanistic methods developed by the author (2004, 2005) [that presently incorporates the dilatancy angle as per Schanz and Vermeer (1996)] and that developed by Pulko and Majes (2006), that takes into account the column yield as per Rowe dilatancy theory. Since optimal design of stone column necessitates optimum stress concentration on column, which is generally composed of dense gravel with/or without sand, the vertical stress on granular column is often close to its peak strength and the material dilates. To arrive at closed-form analytic solution to this complex soil-stone column interaction problem, some common assumptions like axi-symmetric soilstone column ‘unit-cell’, elastic host soil and rigid-plastic Mohr-Coulomb stone column material are combined with equilibrium and kinematic conditions. The results reflect the beneficial effect of dilatancy within the optimal range or techno-economic domain of area-ratio. The settlement predictions are compared with other analytical methods available in literature as well as with measured settlement reduction of stonecolumn reinforced ground at different subsoil conditions around the globe reported in literature.INTRODUCTIONStone columns or granular piles are frequently used in stabilization of soft clays, silts and loose silty-sands with large amount of fines. The majority of analytical methods assume infinitely wide loaded area with end-bearing columns having constant diameter and spacing that approximate to axi-symmetric conditions, and the approach is known as ‘unit-cell concept’. Several analytical solutions are available, and many of them (Aboshi et al; 1979, Balaam & Booker; 1981) are based on elastic approach considering the stonecolumn and surrounding soil as elastic materials. However, elastic methods give the ratio between the vertical stress in the column to soil (stress concentration factor) approximately equal to the ratio of constrained modulus of both materials. This ratio was found to be considerably higher than measured in the field and it is believed that elastic methods may overestimate the effects of stone columns on settlement reduction (Barksdale & Bachus, 1983). The elastic and elasto-plastic solutions presented by Balaam and Booker (1981, 1985) indicate that the problem can be idealized by assuming that the stone column is in a triaxial state and possibly yielding, such that there is no shear stress at the stone-soil interface and no yielding in the soil. Similar assumptions of stone column to be in a state of limiting equilibrium and under a triaxial stress state are considered in other methods also (Priebe; 1976, Van Impe & De Beer; 1983, Van Impe & Madhav; 1992, Saha & De; 1994, Saha; 2004, 2005, Pulko & Majes; 2006). In majority of the methods it is assumed that under load the stone-column yields at constant volume. However, the last three cases cited consider another parameter; the dilation of stone column. In Van Impe and Madhav’s (1992) and author’s (2004, 2005) method, the dilation is taken into account through the final value of the volumetric strain of column, whereas Pulko & Majes (2006) considered the stone column as Mohr-Coulomb rigid-plastic; dilating at yield in line with Rowe (1962) dilatancy theory."

Jan 1, 2015

By Mahdi Soudkhah, Akhter Hossain

Vertical micropiles are generally considered to be low in lateral resistance. Therefore, battered micropiles are often used when additional lateral load carrying capacity is required. However, battering of micropiles can sometimes be restricted due to existing adjacent structures or utilities, especially in highly urbanized areas. For example, presented in this paper are lateral load test data from a 43-story building project in New York City where vertical micropiles were used due to proximity to adjacent structures. Three static lateral load tests were conducted on micropiles consisting of 13.375-in-outside diameter and 25- to 51-ft-long casings, and socketed 10 to 12.6 ft into the bedrock (gneissic schist). The subsurface profile above the bedrock consists of loose to very dense, mostly sandy and silty soils. The design load for the three test piles was 14,000 lb and the maximum load applied during the tests was 200% of the design load. Lateral load- displacement behavior of the free pile heads from the load tests are compared with the results of p-y analyses based on a widely used p-y method for sandy soils and using a lower and an upper bound estimates of soil index properties and strength parameters. Since the existing p-y curves were formulated for larger diameter driven piles at a specific geographic location, major differences are observed between the results of the load tests and the p-y analyses. In general, the lateral displacements estimated based on the p-y analyses using upper bound soil parameters are relatively closer to the results of the field load testing. Modified p-y curves specific to the sandy and silty soils representative of the general subsurface conditions of New York City matched with the lateral load tests are presented in this paper. INTRODUCTION Micropiles generally are limited in lateral load carrying capacities due to their relatively higher slenderness ratios (ratio of depth to diameter) compared to more conventional deep foundation alternatives, such as driven piles and drilled shafts. So, micropiles are not typically considered as deep foundation solutions when significantly high lateral loads are expected on the substructures. Various means to increase the lateral resistance of micropiles include battering and installing an oversized casing in the top portion of the piles (FHWA 2005; and Richard and Rothbauer 2004). However, it is often not possible to install micropiles in a battered position in highly urbanized areas due to existing adjacent structures or utilities. Installation of oversized casing is often restricted by limited space availability and concerns of losing lateral capacities due to closely spaced group of piles. Thus, estimation of lateral resistance of vertical micropiles can become highly important for geotechnical engineering projects in urban areas when a small to moderate amount of lateral resistances are expected from the substructures, often to withstand seismic and wind loads.

Jan 1, 2019

By Nathan W. Iverson, David S. Graham, Paul J. Axtell

"The Highway 53 relocation project in Virginia, Minnesota, involves construction of a very tall bridge across a currently inactive iron ore mine pit. The inactive pit is partially flooded and serves as the community’s drinking water source. The 1,132-ft long new bridge is a three-span, plate girder structure. Two intermediate, approximately 200-ft tall piers are located within the pit.The foundations for the two piers consist of groups of 30-in diameter piles which, despite the contradiction in terms, are essentially very large micropiles. Extremely challenging and highly variable subsurface conditions exist at the site, ranging from uncontrolled iron ore mine waste fill to some of the hardest rock on earth that can also be highly fractured and abrasive. Despite the conditions, large diameter (30-in) micropile foundations up to 175 ft deep were successfully installed using down-the-hole hammer methods and full-length permanent casing under an extremely aggressive construction schedule.Full-scale foundation load testing using the Statnamic rapid loading method was also conducted in support of the design and construction but under a separate pre-design phase contract. This paper describes the unique aspects of this foundation project, including design, construction, and load testing of the large micropiles.INTRODUCTION AND BACKGROUNDIn 1960, a segment of Trunk Highway 53 (TH-53) in Virginia, Minnesota, was built on land owned by iron ore mining interests. As part of the roadway easement agreement, Minnesota Department of Transportation (MnDOT) was to be given notice three years prior to termination of the easement. In 2010, MnDOT received notice that the mining interests wished to access the ore. Through negotiations in 2010, MnDOT and the mining interests agreed to a 2017 date for abandoning the existing section of roadway. During this period, MnDOT needed to procure project funding, satisfy environmental permitting requirements, and acquire new right-of-way to permanently reroute TH-53 and keep it open to traffic. This was no easy task due to the existing mine pits surrounding the area.The E-2 alignment option shown in Fig. 1 was ultimately selected for the rerouted highway in 2014. The new highway segment includes a three-span bridge across the currently inactive Rouchleau Mine Pit. The inactive pit is partially flooded and serves as Virginia’s drinking water source. The 1,132- ft long new bridge is a three-span, plate girder bridge. Two intermediate approximately 200-ft tall piers are located within the pit. Fig. 2 is a conceptual rendering of the bridge."

Jan 1, 2017

By Jason Herron, Joseph Brown

The common couplings for joining sections of helical piles with an outside diameter of 6.625 inches and 8.625 inches are square on square, flange to flange, external pipe sleeve, internal pipe sleeve, and welded joint. Each coupling type has advantages and disadvantages in efficiency, capacity, installation, and economics of the installed pile. All these coupling types have been used in the helical pile market in North America for various applications and designs. Many of these applications require on-site testing, but test records are not typically shared with the helical pile industry. Due to the lack of information available for square on square and flange to flange couplings, testing was done to compare the efficiency of installation, load to deflection response, and torque to capacity ratios of external pipe sleeve, square on square, and flange to flange couplings. Field installations and tension tests were performed in non-cohesive (sand type) soil near Caseyville, IL and in cohesive (clay type) soil in Centralia, MO. The data collected during these tests included rotations per foot during installation, installation torque, applied pressure, and deflection. The results of this testing are analyzed and discussed within this paper. The results indicate that the square to square coupling is the most efficient of the designs tested, but this conclusion cannot be fully justified without further testing due to the variability in the data gathered and the small number of piles tested. INTRODUCTION A helical pile is typically assumed to be a medium-displacement pile when its outside diameter is between 4.5 inches and 8 inches and a high-displacement pile when its outside diameter is greater than 8 inches. A helical pile designer has multiple options when selecting a coupling type for medium- to high-displacement helical piles. Each type of coupling has advantages and disadvantages and must be analyzed on the bases of efficiency, capacity, installation, and economics of a project. Typical couplings that are chosen by designers include square on square, flange to flange, external pipe sleeve, internal pipe sleeve, and welded joint. A helical pile must transfer axial, lateral, bending moment, and torsional loads, and the coupling must be designed to effectively and efficiently transfer each type of load. During the installation of a helical pile, the rate of penetration and the disturbance of soil layers play a critical role in the efficiency and torque to capacity ratio (Kt) of the pile. It is common for a coupling to protrude beyond the outside diameter of the pipe section being used. This is necessary for the function of certain coupling types and can facilitate the connection of couplings. However, it causes increased soil disturbance and reduce the rate of penetration due to soil bearing against the protruding portion of the coupling. A helical pile designer typically will work to minimize the coupling protrusion and create a pile with optimal installation efficiency but may choose a design with lower installation efficiency if it offers sufficient economic advantage.

Jan 1, 2019

By Alexander Filotti, Richard Kalson

"In the last decade, the construction industry has witnessed significant changes in the project delivery systems and contractual relationships between the general contractors (GC) and Deep Foundation Specialty Contractors. The Deep Foundation industry, especially including industry specialty subcontractors, have experienced a significant increase in requests that project risks be transferred through contract documents to subcontractors and suppliers with a decrease in margins for the industry. GCs regularly revise their form subcontracts to take into account recent experiences/contractual trends and newly issued judicial precedent, an exercise that is less frequently undertaken by subcontractors and suppliers. These contradictory trends are at the base of the ethical analysis of subcontracts that comprises the subject matter of this paper. Using contracts as a risk management tool in order to mitigate the general contractor’s risks in the context of dynamic changes in the legislative environment will also be addressed. Furthermore, another possibility for risk mitigation for the industry is to actively promote the introduction of the latest technical developments into the contract documents.CONTRACTS’ ETHICSFor thousands of years, ethics have been a constant presence in our lives and have been debated by different branches of philosophy. In modern times, ethics in business started to be an imperative for the success of a globalized economy.“Ethics are standards by which one should act based on values. Values are code beliefs such as duty, honor, and integrity that motivate attitudes and actions.” (Rumbaugh 2004). Some of these values and actions have been carved in legislation in general and in business legislation in particular. More and more, unethical business practices (e.g., corruption) are identified as the root cause of poverty, underdevelopment, and war around the world. In the context of contract ethics, three aspects are of interest:•,Ethics of contract construction•,Ethics of contracting processes•,Ethics of risk allocation in contracts"

Jan 1, 2016

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 Derrick Dasenbrock, Mary C. Nodine, Benjamin Rivers

Up to 50 percent of major infrastructure projects suffer impacts to schedule or cost due to geotechnical issues, many of which correspond to risks related directly or indirectly to the scope and quality of site characterization work. The Federal Highway Administration (FHWA) in coordination with industry organizations seeks to address this issue through Every Day Counts (EDC), a program that identifies and deploys proven, yet underutilized innovations at the project level to save time, money and resources. The A-GaME (Advanced Geotechnical Methods in Exploration) is one of the innovations supported under EDC.

By Shyam Chengalath, Johan Jeansson, Magnus Hörman

Down-The-Hole (DTH) drilling usually uses compressed air to power the hammer. However, there are now DTH hammers on the market which instead of compressed air use high pressure water to power the hammer. There are several benefits with using water DTH compared to air DTH, which are discussed in more detail in this paper. From a physics point of view many of the benefits arise from the fact that water is an incompressible media and air is not. Energy consumption is roughly a quarter compared to air, resulting in lower carbon emission and a lower energy bill. In the case of water DTH the water leaving the drill bit in the hole is at a low velocity and ambient pressure. However, with air DTH the air leaving the drill bit in the hole is at a high velocity and high pressure. This means that the risk of damaging surrounding structures in sensitive areas such as urban environments and dams, is greatly reduced with water DTH. In this paper two cases where water DTH is used in jet-grouting applications are discussed in detail. As these cases show there is a clear improvement in productivity when using water DTH hammers.

Sep 1, 2022

By Shigetoyo Yasui, Masahiro Saitou, Nobushige Yasuoka, Keisuke Tsujimoto

"The Dry Jet Mixing (DJM) Method was developed and has been put to practical use on the initiative of the Public Works Research Institute and Japan Construction Method and Machinery Research Institute. This method is used to inject powdery binder with compressed air into soft ground while mixing the binder with the soil using the mixing blade to reduce the moisture content of the ground and cause chemical reactions between the soil and binder, thereby strengthening the ground and stabilizing its quality.Recently, there is a demand for high-quality, high-accuracy execution control.This paper introduces the New DJM Execution Control System, developed to meet the future demand for more sophisticated ground improvement, based on the past results of the conventional system in order to provide new automated execution control with improved accuracy, functionality and column quantity.1. INTRODUCTIONIn association with the densification of cities and the improvement of the social overhead capital, the underground space in urban areas is tangled with various underground structures including transportation facilities such as subways and underground roads, buried pipe such as water supply and sewerage systems,gas, electric power and communications lines, and underground malls.In addition, a lot of aboveground structures such as office and residential buildings, elevated tracks, expressways, embankment tracks are also supported with underground foundations.Tokyo, Osaka, Nagoya and many other large cities in Japan grow on plains spread along the coast or rivers. Waterfront flat areas which are very convenient for human activities, however, are often on the alluvial soft ground, where soft cohesive soil with a high moisture content, loose sandy soil, etc. are accumulated in a thick formation, with a high groundwater level.The DJM Method introduced here is used to decrease the moisture content of the soft ground, strengthen the ground and stabilize the soil quality by injecting powdery binder into the ground with compressed air, while mixing the binder with the soil using the mixing blade.2. OUTLINE OF DJM METHODThe DJM Method is used to inject powdery binder with compressed air into soft ground, while mixing the binder with the soil using the mixing blade, to cause chemical reactions between the soil and binder, thereby decreasing the moisture content of the ground and strengthen and stabilize the ground."

Jan 1, 2015