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By Jeffrey C. Evans, Daniel G. Ruffing, Hejintao Huang

Soil-bentonite slurry trench cutoff walls are the most common type of vertical cutoff wall used in the US for seepage control and for passive control of contaminant migration at environmental sites. Design considerations are often limited to constructability considerations and a target hydraulic conductivity. With design-build contracts common, the backfill design is often left to the contractor. As a barrier soil, the hydraulic conductivity of bentonite slurry wall backfill is typically required to be equal to or below 1x10-7cm/s. The importance of stress state upon the hydraulic conductivity as well as the expected stresses are both established in the literature. Grain size distribution of the base soil and bentonite content both affect compressibility and hydraulic conductivity. This paper describes the results of studies undertaken to evaluate the interrelationships between compressibility, hydraulic conductivity, grain size distribution, and bentonite content. Three base soils were used representing a range of soils found on typical construction projects. Using these base soils, mixtures containing a range of dry bentonite contents from 0% to 5% were prepared to a slump consistent with field practice. The compressibility and hydraulic conductivity were measured in consolidometers adapted for falling head permeability tests at the end of each load increment. These experiments yielded the relationship between effective stress and hydraulic conductivity as well as consolidation characteristics including time rate of consolidation and coefficients of compressibility. The experimental results are then used to indirectly evaluate stress development and to assess the time needed for consolidation. The findings show a substantial decrease in hydraulic conductivity as effective stress increases, regardless of base soil type and dry bentonite content, a relative insensitivity of stress development to backfill compressibility, and a wide range of values for coefficient of consolidation depending upon backfill mixture and stress level.

Jan 1, 2016

By Daniel A. Thome, Robert C. Janke

"Installation of permanent soil nails through distressed mechanically stabilized earth retaining walls is a cost effective and aesthetically pleasing solution when using the appropriate equipment and drilling methods for installation. A forensic investigation was performed on an existing mechanically stabilized earth retaining wall to determine the possible causes for the excessive horizontal displacements and visual structural flaws found along a portion of the wall. Reports concluded that the visual shifting was due to a number of factors including improper drainage in the vicinity of the wall and unsuitable compaction of the backfill material. Conceptual designs were proposed to the owner and the installation of permanent soil nails through the existing precast panels was determined to be the most practical solution. A total of ninety-three permanent soil nails were installed to lengths of up to 40 feet (12 m) through sand backfill and silty day fill using a hydraulic rotary percussion drill attached to a tract mounted excavator.IntroductionThe Illinois State Toll Highway Authority awarded Contract RR-03-5144 in the summer of 2004. Construction work for the project consisted of the rehabilitation of two existing concrete culverts and approximately 100 linear feet (31 m) of mechanically stabilized earth (MSE) retaining wall. The retaining wall is located below the southbound lanes of the Tri-State Tollway near the intersection of Federal Highway 41 in Wadsworth, Illinois as shown in Figure 1.Reports were prepared by Applied Technologies in cooperation with Giles Engineering Associates to determine the condition of the MSE wall and recommended conceptual designs to extend the service life of the wall.Nicholson Construction Company (Nicholson) wasselected as the design-build geotechnical subcontractor to install the recommended permanent soil nails through the existing precast concrete panels of the MSE wall. Rehabilitation of the wall involved the installation of ninety-three permanent soil nails through the existing wall, along with soil nail verification tests and proof tests on production nails."

Jan 1, 2005

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 I. D. McPherson, Dominic P. Mahoney

The Metro Sports Facility is currently under development in Christchurch, New Zealand and is a key Anchor Project in the city’s post-earth quake recovery. When completed it will be largest indoor sports and swimming pool complex in New Zealand, with a building footprint in the order of 22,000m2. The site is underlain by poor performing soils comprising interbedded layers of soft compressible silts and loose liquefiable sands to over 20m depth. The site is typical for Christchurch with a shallow groundwater table and artesian conditions. The site performed poorly during the 2010-2011 Canterbury Earthquake Sequence with extensive liquefaction, and associated ground damage. To provide a resilient and economical foundation system for this key development project, deep ground improvement comprising of a uniform grid of some 7,200 stone columns in conjunction with robust shallow foundations has been adopted. This paper discusses the geotechnical site constraints, and ground performance under earthquake loading and describes the various options considered for the development. The foundation option selected, the design considerations of the adopted stone column ground improvement, and foundation solution are described in detail, as well as, construction observations. The paper aims to provide insight into an urban large-scale ground improvement project for the engineering practitioner.

Nov 1, 2022

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 Gerald Verbeek, Erick Baziw

Cone penetration testing (CPT) is a popular and cost effective tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic penetrometer into penetrable soils and recording cone bearing (qm), sleeve friction (fs) and dynamic pore pressure (u) with depth. The measured qm, fs and u values are utilized to estimate soil type and associated properties based predominantly on empirical correlations. The cone bearing measurements are highly susceptible to additive measurement noise for sandy, silty and gravelly soils. This measurement noise results in high peaks due to interbedded gravels and stones and low peaks due to softer materials or local pore pressure build-up. To date there has been little progress in filtering this additive noise aside from ad hoc techniques, which include discarding qm measurements and smoothing/averaging qm measurements. This paper outlines a qm filtering technique which attempts to put structure into the estimation problem. In this case, the dynamics of the cone bearing measurements are modelled within a state-space mathematical formulation and a Kalman filter (KF) is then utilized to obtain optimal estimates of qm. The mathematical details of the qm KF algorithm are outlined in this paper along with the results from a challenging test bed simulation.

Sep 8, 2021

By Gerald Verbeek, Erick Baziw

Cone penetration testing (CPT) is a popular and cost effective tool for geotechnical site characterization. CPT consists of pushing at a constant rate an electronic penetrometer into penetrable soils and recording cone bearing (qm), sleeve friction (fs) and dynamic pore pressure (u) with depth. The measured qm, fs and u values are utilized to estimate soil type and associated properties based predominantly on empirical correlations. The cone bearing measurements are highly susceptible to additive measurement noise for sandy, silty and gravelly soils. This measurement noise results in high peaks due to interbedded gravels and stones and low peaks due to softer materials or local pore pressure build-up. To date there has been little progress in filtering this additive noise aside from ad hoc techniques, which include discarding qm measurements and smoothing/averaging qm measurements. This paper outlines a qm filtering technique which attempts to put structure into the estimation problem. In this case, the dynamics of the cone bearing measurements are modelled within a state-space mathematical formulation and a Kalman filter (KF) is then utilized to obtain optimal estimates of qm. The mathematical details of the qm KF algorithm are outlined in this paper along with the results from a challenging test bed simulation.

Oct 1, 2021

By Monique Nykamp

"INTRODUCTIONTerminal 46 is located just south of downtown Seattle, and is one of the Port of Seattle’s busiest container terminals. The Terminal 46 Redevelopment Project was undertaken to replace the existing 15-m-wide (50 ft) cranes along the apron with 30-m-wide (100 ft) cranes, which can unload larger, post- Panamax ships. The project included upgrading the existing waterside crane rail with new piles and constructing a new land-side rail behind the sheetpile bulkhead. The new piles had to be installed adjacent to the existing apron without causing damage, which was a signifi cant geotechnical challenge due to the soft soil conditions at the site. An instrumentation program performed during the test pile program evaluated this challenge and allowed for the development of specifi c production pile installation procedures that had the least possible effect on construction costs and schedule.SITE HISTORYThe site lies along the west side of Elliott Bay, north of the mouth of the Duwamish Waterway. Prior to development, this area was part of the tide fl ats where the Duwamish River drained into Elliott Bay. Prior to 1970, there were several existing timber piers and structures in the area. In the 1970s, the Port of Seattle constructed a 900-m-long (3,000 ft), 30- m-wide (100 ft) apron to support fi ve, 15-m-wide (50 ft) container cranes. The contained backland area was then fi lled with dredged spoils (sand and silt with organics) and the upper 5 to 20 m (16 to 65 ft) backfi lled with sand and gravel.The existing apron was constructed using 0.4 m (16 in) octagonal prestressed concrete piles to support the precast concrete deck and crane rails. The pile-supported bents were spaced at 6.1 m (20 ft), center-to-center, along the longitudinal direction. Pile lengths typically varied from about 20 to 40 m (65 to 130 ft) with 15 to 26 m penetration below mudline (50 to 85 ft penetration). The slope below the apron was constructed at about 1.75 horizontal to 1 vertical to allow for suffi cient water depth for cargo ships. In most areas, a riprap buttress was placed at the toe of the slope. A typical cross section of the apron is shown on Figure 2.Several stability, settlement and pile driving issues arose during the original construction of T-46 (Pita, 1983). Reportedly, movement of the submarine slope occurred during pile driving, resulting in settlement behind the bulkhead. Pile driving reportedly caused settlement of adjacent piles. In addition, some piles were “running” (dropping quickly under one hammer blow) during installation."

Jan 1, 2007

By Federico Pagliacci, Claudio Asioli, Marco Chiarabelli

"""Rigid inclusions"" are a consolidation method that provides improvement of soft soils thanks to the installation of cylindrical columns made up of a material with significant and permanent cohesive properties, whose stiffness is 500÷5000 times greater than the surrounding natural soil’s. ""Rigid inclusions"" find their application in marginal areas (reclamations, polluted sites) to ensure stability of adjacent structures during construction of new buildings and to reduce the impact of natural disasters (liquefaction in the event of earthquakes, embankment collapse in the event of floods). This paper analyses the “rigid inclusion” construction method, related materials and equipment. Moreover, two performed projects will be illustrated. The first is the restoration of Lungarno Torrigiani Embankment in Florence, Italy. In May 2016, the Torrigiani embankment underwent a structural collapse causing a 3 m. displacement of the riverbank towards the Arno River. “Rigid inclusions” (with 300 mm diameter) have been used to re-compact the loose soil and create a stable working platform for the equipment. The second project illustrates the use of “rigid inclusions” (800 mm diameter and maximum depth of 36.6 m) to control the settlement of a new automatic cold store (30 m high with a 65 x 120 m foot print) for fresh frozen vegetables.RIGID INCLUSIONSIn general, the word ""inclusions"" means a type of consolidation that improves the strength of a soil mass through the inclusion of elements constituted by a material having better characteristics than those of the surrounding natural ground, to improve the overall mechanical characteristics of the treated soil. Inclusions are ""rigid"" when the material introduced into the ground has significant and permanent cohesive properties (concrete or cement mortar) and a significantly higher stiffness (500 ÷ 5000 times) than that of the surrounding natural ground.Typically, medium-small diameters (from 300 to 800mm) with low percentages of treatment (from 2% to 10% of the volume of soil) are employed, ensuring a high quality and consistency of the obtained product, both in terms of diameters and elastic modulus.According to the scope of the project and in urban areas, ""rigid inclusion"" columns can also be performed by means of small diameter drilling rigs (micropiles), weighing less than 20-25 tonnes."

Jan 1, 2017

By Heinrich Majewski, Rob Jameson

"Careful review of site conditions and constraints is essential to select the appropriate shoring system for each project. Key evaluation criteria include the geotechnical profile, groundwater and environmental conditions, adjacent buildings and utilities, schedule and any project specific access or other constraints. Typical earth retention schemes range from rock or soil nail walls, through conventional anchored pile and lagging walls to deep internally braced cut-off systems. The Owner’s design team will often develop the conceptual approach under their design studies, and this is refined with Contractor input through Design-Build or Design-Bid-Build procurement. In downtown San Francisco, underground construction must accommodate a unique combination of variable fill, soil, rock and groundwater conditions, potential for severe seismic loadings, and constrained sites within a dense urban environment. The quarter square mile of San Francisco’s Transbay and Rincon Hill districts has seen repeated cycles of development, destruction and re-building through earthquakes and the economy, and has been intensely redeveloped over the last decade. Over 50 acres of this land has been reclaimed from the Bay since the Gold Rush and within 3 city blocks the bedrock slopes from over 250 FT depth below the fills up to outcrops over 100 FT above sea level. A series of project examples from within this small area illustrate how varied shoring systems have accommodated the highly variable subsurface conditions while offering best value in terms of cost, schedule and appropriate protection of adjacent facilities.INTRODUCTIONA walk of 3 blocks from Rincon Hill on San Francisco’s Harrison Street, north through the Transbay area to Mission Street will traverse an urban zone which has been reinvented twice within its 150 year history in response to major seismic events. This small area highlights the range of subsurface conditions and urban environments which are encountered and accommodated in shoring schemes throughout the city. This route down the north side of Rincon Hill overlies a steep bedrock slope, outcropping over 100 FT above sea level at its south end and dropping to over 250 FT below sea level at Mission Street. A complex overburden soil profile, shaped by seismic activity and changing sea-levels has created layered soils ranging from soft estuary muds, dense sandy strata and deep clay layers, in turn topped with urban fill, frequently contaminated with debris from the Great 1906 earthquake. This route runs parallel to, and 350 yards inland of, the San Francisco shoreline resulting in groundwater elevation close to sea level with almost limitless recharge within granular layers. On the higher slopes of Rincon Hill, groundwater is typically observed flowing on top of and periodically within the fractured bedrock formation. The Transbay and Rincon areas were developed early in the Gold Rush era of San Francisco. After destruction in the 1906 earthquake and fire, they became a transit gateway into the city throughout the 20th Century. Demolition of the Embarcadero Freeway in response to earthquake damage and social pressure has opened this large area to redevelopment within the last 20 years, creating a new commercial and residential hub for the city. In its latest wave of building, planners are developing taller structures with deeper basements, in turn creating new construction challenges. Selection of shoring systems appropriate for these developments requires detailed evaluation. The process must address both the rapid spatial changes in subsurface conditions and the constraints surrounding, and specific to, each site in order to define shoring performance requirements. This paper presents an overview of the subsurface conditions and land use development of the Transbay and Rincon Hill areas, with examples of the shoring systems selected to meet site-specific conditions and requirements. The projects cited range from soil nail wall"

Jan 1, 2017

By Abhirami B., V. Balakumar

Piled raft foundation system is an intelligent geotechnical concept, developed towards reducing the settlement of the raft and the footings by providing pile elements below the raft or footings, as the case maybe. Although a large volume of works has been done on the behaviour of piled rafts by observational studies, the effect of construction methodologies such as deep excavations, the installation methodologies used for piling etc appear to have not been covered adequately. This paper discusses the effect of deep excavations, pile installation techniques and the effect of adding structural elements, based on the data available from published literatures. Based on this study, the performance of the piled raft monitored by the author has been revisited and the results of such a study are discussed.

Nov 1, 2022

By Arunsiva R., Sivaranan S., Venugopal B., Kumaran M.

Being a rapidly developing country, India is undergoing a massive infrastructure phase change remarkably. The construction industry is already set to boom, but the time and space constraints necessitate the employment of heavy plants and machinery to take the foundations deeper than ever. Operating such machinery on soft or poor ground conditions without a good working platform leads to uncertainties with massive loss of men and machinery. Plenty of such cases can be observed on construction sites across the globe. Unfortunately, forming a temporary working platform is given least to no importance in the construction industry, particularly ground engineering. This glitch can only be addressed through standard guidelines or codal recommendations on designing and implementing temporary working platforms issued by regulatory bodies. The present paper highlights the importance of providing the working platform, existing design method for working platforms such as TWf 2019:02 of Temporary Works forum, Building Research Establishment BR470 and a brief discussion on the design and construction of the geosynthetic reinforced working platform with a case study is also included. A pitch has been made on the importance of Indian codes/guidelines for the design and construction of temporary working platforms. These guidelines will ensure the safety of the men and heavy machinery and, in addition, increase the productivity of foundation construction irrespective of weather conditions and also become part of the regular construction scope.

Sep 1, 2022

By Alok Bhowmick

The most uncertain and challenging part of a bridge design and construction is the ‘Choice of foundation’. During the planning and conceptual design stage, it is extremely important to choose the right type of foundation. Wrong choice can lead to disaster for the project. This paper will present three interesting case studies of past bridge projects, to demonstrate how correct choice of foundation can help to meet the project commitments while the wrong choice of foundations can led to huge delay in project completion, leading to time and cost overrun.

Nov 1, 2022

By Lee R. Buhagiar

As a result of the increased seismic risk and the highly variable geology of Christchurch, finding costeffective foundation solutions has been a challenge for the Canterbury rebuild. The soil profile in Christchurch comprises both terrestrial (Springston Formation) and marine (Christchurch Formation) alluvial deposits with a high groundwater table. The result is a highly variable and interbedded soil profile which is prone to liquefaction and static settlement. Vibro-replacement stone columns are very effective in mitigating liquefaction in clean sand. However, the author’s experience has shown that vibro-replacement stone columns are also effective for treating silty and soft soil layers. Vibroreplacement stone columns can be used to treat these soft soils by increasing the composite soil stiffness and providing a load transfer path to the underlying dense soils. Another challenge encountered in the Canterbury rebuild is the cost of redevelopment of brownfield sites with contaminated fill. The costs of disposing this fill often make projects too expensive. Vibro-replacement stone columns have been used successfully to treat contaminated fill, providing a treated soil profile with uniform performance and reducing the cost of disposing of contaminated fill. This paper looks at several case studies in Christchurch, with highly variable soil profiles, where vibro-replacement stone columns have been used successfully to treat multiple soil layers, from contaminated fill to silty soils and soft and non-liquefiable silt.

Nov 1, 2022

By William M. Tanner, Daniel C. Brahana

"A drilled pier foundation was originally designed to support the proposed G. Wayne Clough Undergraduate Learning Commons on the campus of Georgia Tech in Atlanta, GA. Reflective of the site geology, the original drilled pier foundation was divided into a Northern and Southern portion with an allowable end bearing capacity of 60 ksf and 100 ksf, respectively. After initial pricing on the original design, several value engineering options were submitted that featured changes to the original design capacity and construction method. The project team selected the value engineering option that involved conducting an Osterberg Load Cell test to assess end bearing of the site bedrock and skin friction. Results of the Osterberg Load Cell test justified increasing the allowable end bearing capacity of the site bedrock to 100 ksf in the Northern portion and 125 ksf in the Southern portion. Considering the final foundation design and Osterberg Load Cell test program, a net savings of approximately $259,000, or approximately 34%, was obtained over the original design.Project BackgroundThe G. Wayne Clough Undergraduate Learning Commons (CULC) is a 5-story academic building on the Georgia Tech campus in Atlanta, Georgia. The CULC was completed in 2011 and consists of a concrete frame structure supported on a drilled pier foundation.After pricing of the original drilled pier foundation design, several value engineering (VE) analyses were performed by the foundation contractor in an effort to demonstrate the potential for a reduced foundation cost. The VE analyses focused on variations in design assumptions, as well as construction techniques. This paper presents a case study that demonstrates how the value engineering process can be used to reduce foundation costs.Site Investigation and Subsurface ConditionsThe CULC building site is located within the Southern Piedmont Physiographic Province, an area underlain by metamorphic and igneous rocks. McConnell and Abrams (1984) indicate that the site is located at the boundary between two distinct geologic formations. The Northern portion of the site is underlain by the Wahoo Creek Formation while the Southern portion of the site is underlain by the Stonewall Formation. The following paragraphs briefly describe the geotechnical investigations performed by the project geotechnical engineer (GE) for the CULC."

Jan 1, 2015

By Joseph A. Mann

"Soil mixing is a proven solution for the construction of ground improvement adjacent to sensitive structures due to the use of computer controlled and monitored equipment. The precision to which geometry is controlled can often be the deciding factor for selection of soil mixing versus other means of ground improvement. Protection of existing structures and utilities requires careful planning, investigation, and may demand supplemental control measures. During planning, it is imperative that the process be fully developed by the project team to ensure proper control measures are budgeted; otherwise, the success and safety of a project can be jeopardized.This paper discusses case histories of soil mixing performed in close proximity to large, sensitive, and critical utilities, including foundation support for an existing earthen dam impounding a water reservoir in upstate NY, a buffer zone for a tunnel drop shaft at an operating wastewater treatment plant in Washington DC, and a containment system to protect a major water line along an interstate widening project in Baltimore, MD. The function of soil mixing as ground improvement varied; however, the selection and application of the technique versus other means of ground improvement was specific due to the controlled manner of construction with soil mixing. Through the three case studies, small diameter (3- ft [0.9 m]), large diameter (8-ft [2.4 m]), and mass mixing applications will be discussed. Furthermore, the case studies offer insight into how the geotechnical community in the Mid-Atlantic utilizes soil mixing technology for widely varying applications. Additional topics of discussion will be the design and construction of the ground improvement systems, procedures and execution of the work to protect existing structures, and the QA/QC methods, procedures, and results from the projects.INTRODUCTIONWet soil mixing, also known as the Deep Mixing Method, is a ground improvement technique that improves the characteristics of weak soils by mechanically mixing them with cementitious binder slurry. To construct columns, a powerful drill advances a mixing tool with radial mixing paddles located near the bottom of the drill string. The binder slurry is pumped through the drill string to the tool as it advances and additional soil mixing is achieved as the tool is withdrawn.Wet soil mixing is applicable in a wide range of soils. Soil mixing has been performed at depths more than 100 lf (30 m). Soils vary widely in their ability to be mixed, depending on the soil type, strength, water content, plasticity, stratigraphy, and texture. Almost any soil type, including organics, can be treated with certain soil mixing technologies, although they may require high binder contents and/or pretreatment to achieve the required results. In cases when the target soil is very soft, including some very weak clays and peats, 100% of the soil may require treatment. This complete coverage of soil mixing is referred to as mass mixing."

Jan 1, 2015

By Lok M. Sharma

Development of brownfields is of great interest in these days. Such fields are not easily adaptable for foundations of structures. The uncertainties in ground behavior present challenges of unpredictable subsidence that could be detrimental to the build up facility. A desalination plant had to be located along the seashore, close to the needy population and the existing water supply infrastructure. The available site had been developed as a recreational park area over a dumped construction demolition debris landfill along the coastline. To construct a desalination plant comprised primarily of large concrete basin tanks on slab, founded on the debris fill had its challenges. A ground improvement system in the form of vibro replacement stone columns was designed and constructed. Approximately 5,000 stone columns were installed across the site. This paper describes the analysis process, the design, field load testing, and installation of stone columns. Difficulties during construction and monitoring aspects are briefly described. The plant started operations in the summer of 2008 and to date has performed satisfactorily. When properly designed, the development of brownfields is achievable at other sites.

Jan 1, 2009

By Michael Perlow

Helical screw piles in use since 1838 are routinely used for energy, transportation, municipal, industrial, marine and coastal infrastructure as well as for excavation support, environmental remediation, and foundation repair. They are especially well suited for work in constrained areas, renovations and structure retrofits. Helical pile design procedures over the past 10 years have gone through a remarkable evolution with the establishment of the 2007 AC358 Helical Pile Acceptance Criteria and inclusion of helical screw piles in the 2009 International Building Code (IBC). New 2009 IBC building code requirements and AC358 Acceptance Criteria are presented along with advances in helical pile design procedures, installation, QA/QC, and recommended load test verification criteria. Use of helical smart piles to validate helical pile design and verification of ultimate pile capacity is highlighted.

Jan 1, 2011

By Michael Moran

Typical ACIP Pile Rig [ ] Hollow Stem Auger ? Continuous flight auger ? 3 inch inside diameter pipe ? Auger diameters: 12, 14, 16, 18, 20, 22, 24, 30, and 36 inches ? Auger section lengths: 4, 5, 10, and 20 ft ? Weight ranges from about 70 lbs per ft for 12 inch to 120 lbs per ft for 24 inch and 200 lbs per ft for 36 inch

Jan 1, 2005

By Joel L. Volterra

Since 1910, Mueser Rutledge Consulting Engineers (MRCE) has regularly provided professional engineering services including inspection of pile load tests. Historically, such services included on-site inspection of the driving of test piles and subsequent static load tests by qualified Geotechnical Engineers. Load testing procedures are specified by local or State Building Codes, locally the 1968 Building Code of the City of New York (1968 BCCNY). Between 1968 and 2008, the 1968 BCCNY required a minimum 48-hour hold period for standard loads per pile type, an extended 96-hour hold period for higher capacity piles, and a settlement criterion that the pile maintain a test load equal to two times the design load with less than 0.012 inches of settlement over the last 48 hours of the hold period. Effective July 2008, the new 2008 BCCNY shortened the hold period and relaxed the settlement criteria to that which is more similar to other governing codes and standards such as the International Building Code (IBC 2006) and the American Society for Testing and Materials (ASTM). MRCE implemented an automated load test monitoring system to reduce costs and to alleviate or minimize overnight and off-hour staffing for load test readings. Initially, a series of linear variable differential transformers (LVDTs) and data loggers were included in the Contractor?s load test setup to electronically record pile head settlement and where applicable, settlement of telltales installed to varying depths in the pile. A pressure gage was subsequently added in the hydraulic line, then a load cell, strain gages, and remote access using modems. The ease of the setup and modular adaptive nature of this system have proven it to be a useful tool and improved our ability to better serve our clients and manage our pile load testing services.

Jan 1, 2008