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By Donald Deardorff

"Helical piles often rely on the final installation torque for ultimate capacity verification. When helical piles are designed using traditional bearing capacity equations for deep foundations and field monitored for a specified final installation torque, a factor of safety equal to 2 is often allowed for the design. One of the more common methods of determining torque during helical pile installation is by correlating the differential pressure across a hydraulic gear motor to a torque. Most drive head manufacturers provide multipliers to convert differential pressure to torque for different drive head models. These multipliers are based on theoretical torque equations and vary with the planetary gear ratio, hydraulic gear motor displacement and drive head efficiency. Drive head manufacturers show a linear fit between the differential pressure and output torque with no scaling effect. Previous drive head testing performed by the author has confirmed that the drive head differential pressure to torque relationship is generally linear however there is a scaling adjustment needed. This results in a variation of multipliers across the differential pressure range for a given drive head.Eight hydraulic drive heads from three manufacturers were field tested by Foundation Supportworks, Inc. to compare the torque versus differential pressure curves with varying installation equipment, hydraulic line sizes and hydraulic flow rates. Differential pressure was monitored using three methods including pressure gages, PT-Tracker and an Ashcroft AT-100. Flow and temperature was measured using a Webtech system analyzer. Torque was measured using a Pro-Dig in-line torque transducer, a TruTorque indicator and a Chance Mechanical Dial in-line torque indicator. The current testing indicates that a change in installation equipment and/or a change in hydraulic flow rate may affect the torque versus differential pressure curve of a given drive head. The results of this testing also show that some of the methods for determining torque during helical pile installations may be unconservative, thereby resulting in safety factors less than required."

Jan 1, 2017

By Edward C. Clukey

A deep mixing method (DMM) foundation was selected by the Project Team for a very largeLNG facility in West Africa. As described in a companion paper, this foundation consists of alarge number of columns installed by mixing cement with in-situ soils. The foundations arearrayed as a variety of honeycombed type configurations which, if installed to desiredspecifications, can provide a robust foundation alternative. The foundation is capable ofdistributing loads and limiting settlements even if some of the soil in the columns is not fullymixed during installation. An important part of the overall quality assessment program,therefore, involved developing a testing program to verify the methodology. In addition theimpact of potential defects in columns on the overall foundation integrity had to be assessed.This paper describes some of the preliminary work done to establish the requirements for thequality assurance program. A key component of this program involved the samplingfrequency used to assess potential defects in the columns. To verify the column integrity 104-mm samples were taken continuously at a selected frequency through the 23 m longcolumns. The preliminary work described in this paper demonstrated that the appropriatesampling frequency depends on both the desired reliability level as well as the number ofdefective columns encountered during testing. Initial finite element analyses were performed to assess the extent that defects could occur incolumns within the honeycombed structure without adversely affecting the overall foundationintegrity. The results from this work demonstrated that the spatial location of the defects wascritical to properly assessing the foundation integrity. In addition to column sampling a load test was performed as part of the foundationverification process. The methods used to apply appropriate loads so that loads at thebottom of the columns approached design values are discussed in the paper. The results obtained from this preliminary study were then used to help develop a morecomprehensive assessment program, described in a companion paper, to determine therobustness of the DMM foundations for both the LNG processing facilities and a condensatetank.

By Paul Summers, Kevin Richardson, Willem (Billy) Villet, Paul J. Sabatini, Attasit Korchaiyapruk, Edward C. Clukey

"A deep mixing method (DMM) foundation was selected by the Project Team for a very large LNG facility in West Africa. As described in a companion paper, this foundation consists of a large number of columns installed by mixing cement with in-situ soils. The foundations are arrayed as a variety of honeycombed type configurations which, if installed to desired specifications, can provide a robust foundation alternative. The foundation is capable of distributing loads and limiting settlements even if some of the soil in the columns is not fully mixed during installation. An important part of the overall quality assessment program, therefore, involved developing a testing program to verify the methodology. In addition the impact of potential defects in columns on the overall foundation integrity had to be assessed. This paper describes some of the preliminary work done to establish the requirements for the quality assurance program. A key component of this program involved the sampling frequency used to assess potential defects in the columns. To verify the column integrity 104- mm samples were taken continuously at a selected frequency through the 23 m long columns. The preliminary work described in this paper demonstrated that the appropriate sampling frequency depends on both the desired reliability level as well as the number of defective columns encountered during testing.Initial finite element analyses were performed to assess the extent that defects could occur in columns within the honeycombed structure without adversely affecting the overall foundation integrity. The results from this work demonstrated that the spatial location of the defects was critical to properly assessing the foundation integrity.In addition to column sampling a load test was performed as part of the foundation verification process. The methods used to apply appropriate loads so that loads at the bottom of the columns approached design values are discussed in the paper.The results obtained from this preliminary study were then used to help develop a more comprehensive assessment program, described in a companion paper, to determine the robustness of the DMM foundations for both the LNG processing facilities and a condensate tank.IntroductionFoundations constructed with the Deep Mixing Method (DMM) can be an attractive and cost efficient alternate to other deep foundation options. This foundation is constructed by mixing soil and cement with an auger type drill. The foundation is usually constructed with a dual auger system that simultaneously creates two contiguous columns called foundation elements. Many elements are then arranged in a honeycombed configuration to create the overall foundation (Figure 1). A desired column strength can be obtained by varying the volume of cement added to the columns, the mixing rate of the soil and stroking sequence."

Jan 1, 2017

By Aly M. Mohammad

The design of large diameter drilled shafts in weathered rock has always presented a challenge to the foundation engineers. Degree of weathering and load transfer mechanism through the rock are essential elements required for the design. From the Contractor's perspective specifying the right equipment and estimating the rate of drilling in the weathered rock are key elements for successful construction. The Delaware River Tramway Project has provided an opportunity to address the design and construction of drilled shafts in weathered rock. The Tramway, supported by twin 300-foot towers, will shuttle eight-person gondolas across the Delaware River in about four minutes. Each tower, founded on four high capacity drilled shafts, is designed to resist large axial and lateral loads. At the New Jersey tower, each 7-foot diameter shaft extends 145 feet deep and terminates in weathered Mica Schist. The shafts are situated in the Delaware River where the mud line is approximately 20 feet below Mean Low Water. Below the mud line, there exists a very soft, 20-foot thick layer of organic silt, followed by a 40-foot thick dense sand stratum. Below these sand and silt strata, a 70-foot thick layer of weathered Mica Schist underlies the entire site. Both skin friction and end bearing in the weathered rock stratum were utilized in the analysis to compute the axial capacity. AASHTO and the PennDOT design methodologies were utilized independently during design of the drilled shafts to verify the design. The drilling of large diameter drilled shafts embedded into weathered rock and situated in a marine environment provided a unique challenge in the construction. A permanent steel casing was installed for a specified depth and proper equipment was used to drill and keep the shaft open through the weathered rock. In addition, a 5000 kip Osterberg load test was performed on one shaft to verify design assumptions and confirm the shaft capacity. The results of the test were utilized to establish load transfer characteristics within the weathered rock and to develop foundation design parameters to be used for the remaining shafts.

Jan 1, 2003

By Davide Grassi, Joel Joaquin Cortez, Giovanni Spagnoli, Nick Chittenden

Grouting is a technique used to improve the engineering properties of soils and rocks. Grouting techniques are classified under different criteria: injection method used, type of grout material injected, typical application, and the sequence of construction. The best-known criterion is the mode of entrance or admission of grout into the soil or rock. It is possible to identify therefore several grouting techniques: compaction, fracture, jet/mixing and permeation. The function of penetration grouting is to reduce the permeability of the soil or rock and/or increase the strength and density. In order to avoid displacement, permeation grouting shall be carried out at carefully controlled pressures and flow rates, using appropriate grouts. Colloidal silica is an innovative binder which has low viscosity (about 5 m·Pas), it is not toxic (pH lower than 9) and it is workable between +5°C and +45°C. This paper presents several case histories: a consolidation job related to the installation of a new sewer in North Italy in cohesionless soils, water stopping injection in a weathered granitic bedrock in California, permeation works in the US in sandy soils to improve excavation and the installation of sheet piles in the UAE. Results show that the colloidal silica an innovative and robust technology to perform grouting in very fine soils where conventional binders or micro-fine cements cannot penetrate.

May 1, 2022

By Ambarish Ghosh, Subhaprasad Chakraborty

"Construction of basement floors has become necessary to meet the requirement of parking in office and residential complexes and in hospitals for radiotherapy treatment. Important projects coming up in Kolkata are mostly in closer proximity of residential buildings, office buildings and historical monuments. Sheet piling is mostly used as temporary shoring system during construction. Deep excavation in urban environment creates great problem related to construction induced vibration due to driving of sheet piles for basement, pile driving etc. which raises the chances of damage of adjacent buildings and nearby structures. Vibratory sheet-pile driving is the most common method of sheet pile installation. The knowledge of induced vibration due to this phenomenon is still very deficient. This paper presents the analysis of measured vibration data collected from different sites of Kolkata with varying soil profile. Typical two case studies of sheet pile and pile driving has been presented and the vibration values are analysed. The responses of the vibration are reported in terms of peak particle velocities (PPV). To evaluate the effects of vibration due to pile driving two aspects have been considered: the effect of the energy entering the ground from the pile and the effect of the soil condition.INTRODUCTIONIn urban areas infrastructure development projects are mainly located adjacent to existing structures like residential buildings, offices and historical structures. The construction work of such project influences the surrounding environment as well as human perception (Wiss 1981). During the construction of basement for residential complexes and hospitals sheet piling is mostly used as temporary shoring system or as to support the earth mass. The vibration induced due to driving of piles and sheet piles have been presented herein. Deep excavation projects close to existing structures increase the concern of environmental impact. For this reason the vibration assessment and prediction has become a subject of great interest. It is important to develop a site specific model for predicting the ground vibration resulting from pile and sheet pile driving at the construction sites. The developed model gives the efficacy to guide the engineer to select the construction methodology ensuring the safety of the surrounding structure. The model developed here is site specific and the parameters that has been used are dependent on the soil condition and the energy source."

Jan 1, 2015

By Shoichi Tsukuni, Akihiko Uchida, Kazuo Konishi

"In order to investigate the effect of grid-form deep mixing walls as a countermeasure for liquefaction damage to roads and private houses in Urayasu, Japan, three dynamic centrifuge model tests were conducted. Urayasu is located in the Tokyo Bay area, and private houses in the city incurred severe damage due to liquefaction during the 2011 Tohoku earthquake. In grid-form deep mixing walls design, the distance between grid-form walls is critical to prevent liquefaction. This study clarifies the relationship between the settlement of private houses and the distance between grid-form walls under the conditions that exist in Urayasu.INTRODUCTIONMany private houses in Urayasu, Japan suffered severe damages due to liquefaction during the 2011 Tohoku earthquake (Photograph 1). Fig. 1 shows the location of Urayasu and the maximum acceleration of the observed seismic waves in the Tokyo Bay area. At Urayasu, the duration of the seismic waves (hereafter called the Urayasu Wave) was about 2 min. The maximum acceleration was 1.57 m/s2 (Fig. 2), which is relatively small. The damages occurred in the land reclamation areas that consist of loose sand with an SPT-N value less than 10.To prevent liquefaction in future, it is necessary to adopt suitable countermeasures in the areas where many private houses suffered severe damages. Grid-form deep mixing walls are one such countermeasure. Fig. 3 and Photograph 2 show grid-form deep mixing walls. Walls are constructed using the deep cement mixing method. Fig. 4 shows a plane view of planned grid-form deep mixing walls for roads and existing private houses in Urayasu."

Jan 1, 2015

By Carl Ealy

Static and STATNAMIC (STN) rapid load test (RLT) was performed on 3-drilled shafts. The purpose of the RLT part of the study was to obtain data in support of FHWA research on innovative load testing methods. The research site is located at the National Experimentation Research Site (NGES) in Amherst Massachusetts and is underlain by Connecticut valley varved clay. Two of the tested shafts were constructed without planned defects and the third with manufactured defects to evaluate current non-destructive integrity testing (NDE) methods. Quick Load Test (QLT) and Constant Rate of Penetration (CRP) static axial load tests were performed on two shafts to plunging failure. Good agreement between static and RLT derived static failure loads was attained for a 5% failure criterion (load at a movement equal to 5% of shaft diameter).

Jan 1, 2002

By George Gazetas, Sissy Nikolaou, Fani Gelagoti, Irene Georgiou, Rallis Kourkoulis

"The need to shift geotechnical design from a “factor of safety” to a “performance based” design (PBD) approach has increased rapidly in the past years following examples from structural engineering. PBD supports sustainable engineered systems that target project-specific geotechnical behavior objectives and results in more rational and, in most cases, less conservative solutions. Resiliency, efficiency, risk optimization, and cost-effectiveness are key components of this approach. For design of retaining walls, the concept of mechanically stabilized earth (MSE) systems combines these attributes, while being environmentally friendly and adaptive to variable construction conditions. Natural hazards, such as earthquakes, may drive the design of MSE systems whose reliability depends on their performance under extreme events. In this paper, the authors compare the seismic response of an MSE steel-reinforced vs. concrete-reinforced retaining wall. The MSE system is composed of a grid of longitudinal and transverse ribs which internally enhances the capacity of the soil backfill. Results of fully non-linear twodimensional (2-D) numerical finite element analyses using two commercial programs with emphasis on the interface conditions are presented. The pull-out resistance of the grid used in the numerical simulation was evaluated from actual pull-out experiments. The results demonstrate a superior performance of the MSE system as compared to the concrete one, especially when subjected to strong seismic excitations.INTRODUCTIONThe idea of performance-based geotechnical engineering is not new, and has been evolving as our perception for ‘good’ performance has also evolved (Kramer, 2008). In early practice, the only criterion for achieving good performance was to avoid failure; designers had only to ensure that the available capacity of the geotechnical system is sufficiently higher than the expected demand (i.e. Load and Resistance Factor Methodologies). Yet, even when the key design requirements against collapse are satisfied, the system may still be placed into a condition in which the deformation constraints are not met (Bolton, 2012). To address these issues, geotechnical design has been developing into a predominantly performance-based approach that correlates deformation considerations to the severity of the experienced loading. As such, in earthquake-related problems, the definition of good performance of a geotechnical system is no more unique; for a low intensity earthquake the system should remain serviceable (i.e., the developed deformations should remain low), whilst for the design earthquake the maintenance of lifesafety is the single performance criterion."

Jan 1, 2016

By Peter Iovino

Unfortunately, I don't know the unit cost per cubic yard of treatment. I reflected on that yesterday and I don't think that we considered the use of micropiles. They could have been an option. The challenge may have been picking up some of the lateral load but I think the micropiles could have been installed on a batter and perhaps extended to rock. We could have considered them, but I do not believe we explored micropiles as an option for this project.

Feb 10, 2003

By Fredrik Sarvell, Harald. Ihler, Veli-Matti Uotinen, Jukka Rantala

"Many of the valid international building codes state that the lateral support provided by the soil is sufficient to prevent buckling of fully embedded piles. However, the development of small diameter micropiles and especially the use of high strength steel have evolved to applications including high capacity elements. The ultimate structural load bearing capacity of a pile in a cohesive soil is decided by examining which gives the lowest value, the peak buckling load and the resisting moment provided by the surrounding soil medium or the structural capacity of the pile cross section. In both cases, the initial deflection of the pile is a significant factor when the axial load bearing capacity of the pile is determined. Steel micropiles are joined commonly with mechanical splices. A less rigid mechanical splice is often a weaker hinge that allows the pile to bend and deflect more during installation increasing the initial deflection of a pile. In addition the less rigid splice element decreases the bending capacity of a jointed pile section and the ultimate axial load capacity of the entire pile. A series of FE analysis performed for various pile sizes suggest that the steel pipe piles including separate pile sections and mechanical splicing elements should have the combined bending stiffness of EIshaft = 0,75 × EIpile. This requirement yields to the buckling resistance of at least 96 % of the solid reference pile with the sameinitial eccentricity in similar soil conditions.IntroductionMany of the valid international building codes state that the lateral support provided by the soil is sufficient to prevent buckling of fully embedded piles. However, the development of small diameter micropiles and especially the use of high strength steel have evolved to applications including high capacity elements. The potential buckling of these very slender high capacity piles in soft soils may in many cases be the controlling design factor of the pile, especially with end bearing micropiles.A typical sequence of soil strata in Nordic countries, such as Norway, Finland and Sweden, constitutes of friction soil or dry crust clay on top of soft clay followed by till. This soil stratum often rests on solid bedrock of granite or gneiss. Conditions like these are suitable for slender end bearing piles subjected to buckling and especially steel pipe piles where most of the material is located at the edge of the cross section. Other reasons for using slender steel pipe piles are for example fast installation with minimal waste, efficient manufacturing and relatively well established design and execution procedures. Minimum quality criteria’s regarding splices for steel pipe piles are recommended to be set as national provisions to ensure quality and comparable procurements in foundation business."

Jan 1, 2014

By Charles Roeder, Amy Leland, Dawn E. Lehman

Concrete filled steel tubes (CFSTs) are composite members that are commonly used in many countries today. CFST components are used in the United States, but they are more common in Asia, in part because the connections used in Asia are quite labor intensive and there are not standard connections in the U.S. In addition, US design specifications are prepared by separate groups for structural steel and reinforced concrete structures and so composite systems that use CFST components are not overseen by a single group and as such there are several, conflicting design standards. In the US, steel tubes used for CFST are more slender (i.e., the diameter-to-thickness, D/t, ratio is larger) than some other countries, and labor practices (structural steel labor is different than reinforcing steel labor) also cause potential conflicts in construction. As a result, CFST has had some use in tall building construction in the US, but very limited use in bridge construction. A research program at the University of Washington has been in progress to address many of these issues with an eye towards universal design expressions, simpler, standardized connections and promotion of accelerated bridge construction (ABC). The research has resulted in recent changes to the American Association of State Highway Officials (AASHTO) bridge design specification as well as state departments of transportation (DOTs), which supports the increased use of CFST in bridge pile and drilled-shaft foundations. An experimental research study which investigate the flexural strength, shear strength and connections was conducted. These connections provide good performance under both seismic and gravity loads and address the concerns of US construction. These connections, their design rules and requirements, and their impact on composite behavior and system performance are discussed. These results permit rapid and economical construction of CFST bridge piers, piles and drilled shaft foundations. They encourage the use of more slender and economical tubes, while achieving the benefits of composite construction. INTRODUCTION Concrete filled steel tubes (CFSTs) are widely used for bridge and building construction in Asia, but the use of CFST in bridge construction is limited in the US. The historical use of structural steel and reinforced concrete in US bridge construction have resulted in more developed design expression for those construction methods, which has limited the use of CFST. Bridge construction in the US is inherently different than in Asia because of differences in codes, labor costs and construction practices. As a consequence, design and construction practices that are economical and practical in other countries may not be practical for US bridge construction.

Jan 1, 2019

By Andres M. Baquerizo, Matthew E. Meyer, Carlos Ortiz

"The Metropolitan Miami development, a downtown mixed-use complex developed by Miami-based MDM Development Group, has weathered the economic downturn by adapting to the needs and pressures of the local market. The development (a.k.a. Met Miami) epitomizes the term “mixed-use urban development” with its combination of condominium ownership, rental apartments, hospitality, office and retail components within Miami’s urban core. Initially conceived and conceptualized in 2004, the development has gone through several concept changes. Today, the global USD $900 million development approaches completion.The foundation evaluation, design and construction for this development included the use of innovative and state-of-the-art augered-cast-in-place (ACIP) piles. The testing for these elements included (1) the first-ever, multi-level O-cell load test of an ACIP pile, (2) a world record 5,200 ton (46,261.5 kN) equivalent top load test of an ACIP pile, and (3) continued the advancement of the ACIP pile industry to include the deepest and largest diameter pile installation to date. Those dimensions were up to 36 in (914 mm) in diameter, and 120 ft (36.6 m) deep. The project showed ACIP piles were a proven alternative for structures exceeding 70 stories in South Florida.The development includes four parcels. Met 1 and Met 2 are completed, and the construction of the Met 3 development is just beginning, with completion expected in 2014. Once the Met 3 development is completed, the design and construction phases of the project will have spanned a decade. The Met Square portion of the development, which will be a retail and cinema component, is proposed for the parcel between Met 1 and Met 2."

Jan 1, 2012

By Yazen Khasawneh, Osvaldo P. M. Vitali, Mohammad Nassim

The demand for renewable energy is growing as the conventional energy resources are becoming more limited and we are more conscious about the negative impact of conventional energy sources on the environment. Wind turbines technology is evolving in a fast pace, the towers are becoming taller, and the rotors are getting larger. The challenge is to maintain the Levelized Cost of Electricity (LCOE) as low as possible to ensure a sustainable and an economically feasible energy supply. Thus, the foundation systems for wind turbines should evolve to meet the increasing load demand, while reducing the LCOE. In this paper, an innovative foundation system for onshore wind turbines is presented. The new foundation system is the conventional P&H tensionless pier foundation (PHTP) with a reinforced concrete collar at the top of the pier. 3D FEM modeling was conducted to assess the benefits achieved by adding a collar at the top of the PHTP foundation. The numerical results show a significant performance enhancement of the proposed foundation system over the conventional PHTP foundation. The enhanced foundation system also has an economical advantage because the depth of the pier can be greatly reduced while maintaining a superior performance.

Sep 8, 2021

By Deep Foundation

Whenever an organization launches an initiative, the question arises whether that initiative has staying power. Or is the initiative, as is quite often the case, merely a fad; that is, just an activity that suddenly becomes popular, but which does not stay popular for very long. When the Federal Highway Adminis- tration (FWHA) started its Advanced Geotechnical Methods in Exploration (A-GAME) initiative, that question was addressed, especially considering the fact that up to 50% of major infrastruc- ture projects suffer impacts to schedule or cost due to geotechnical issues. Many of these issues relate to risks identified directly or indirectly to the scope and quality of site character- ization work. Effective site charac- terization is critical for recognizing. potential problems that may affect design and construction and for ensuring safe, well-performing and cost-effective projects. Grounded on that, knowledge of all available site investigation methods should continue to be shared widely and the application of those methods should be encouraged on an ongoing basis throughout the project lifecycle. The A-GAME initiative covers five technologies: Cone penetration testing (CPT), monitoring while drilling (MWD), electrical geophysical methods, seismic geophysical methods, and optical and acoustic televiewers. Of these, three soil and rock investigation methods were highlighted that are underutilized not only here in the U.S., but also in many places around the world: CPT: a well proven and established method for soil characterization that turned 90 last year, in which continuous in-situ data are col- lected quickly and consistently. Geophysics: the science that assesses the physical properties of the soils and rock using seismic and electrical techniques, which con- tinues to advance in leaps and bounds as the application of well- understood technologies become more powerful.

May 1, 2023

By K. S. Ho

With the aid of the advanced electronic devices and micro-processors, the quality control of deep foundations can be carried out by Non-Destructive Tests (NDT). Three methods are presented here: the Sonic Logging, Vibration and Stress Wave Analysis Methods. The principles, equipments used, testing procedures and applications are fully described. The correlation of these methods with the conventional tests (mechanical coring and loading test) are studied to give a better understanding of the methods. Several case histories with the test results obtained from a number of sites in Hong Kong and overseas are discussed to show how the pile quality can be examined and especially, how to confirm the effectiveness of remedial works on a defective pile. Recommendation on the percentage of piles to be tested are given at the end of the paper by using statistical method.

Jan 1, 2010

By Daniel Ruffing, Jeffrey Evans

Vertical cutoff, or barrier, walls are an integral part of environmental site remediation efforts. Vertical barriers are commonly deployed to limit the influx of clean ground water and/or to control the off-site migration of contaminated groundwater. The level of detailed design consideration devoted to the vertical cutoff wall component varies widely from project to project and generally decreases with decreasing size and complexity. For those projects receiving minimal design effort, conservative design decisions can lead to unnecessary costs or unanticipated conflicts between the various design considerations. In this paper, the authors discuss several important design and construction aspects of vertical cutoff walls requiring particularly careful consideration during the design phase of the project. These design and construction considerations include the need for and extent of excavation for a key, project target hydraulic conductivity, the use of statistical allowances in the specifications, filter press testing, sand content of in-trench slurry, cleaning of the backfill slope, measurement of stress and strain, the additional of slag in cement-bentonite cutoff walls, and longevity of cutoff walls.

By Tiruvengala Padma, Nilesh Naik

Piles are common type of deep foundation elements used for the special bridges, transmission towers, Jetties, and tall structures. Lateral loads on the structures can be due to either earth pressures, wind, waves, impact, moving vehicles and eccentric application of axial loads or in combination of the loads. Hence the lateral capacity of piles plays a major role in determining the pile dimensions. The laterally loaded pile analysis is a soil-structure interaction problem as the lateral capacity of pile depends on the soil strength and stiffness parameters and its reaction to the lateral load on pile. The common approach to determine the lateral load analysis of piles is the Beam on Lateral Springs Method also known as “p-y” method. In this method the pile is modelled as a beam and supporting soil is modelled as lateral springs. This study is focused on the comparison of output obtained from three geotechnical softwares namely FB-MultiPier, L- Pile and Wallap. L-Pile Software is based on Finite Difference Method, Wallap on Horizontal Subgrade Modulus Method and FB MultiPier on Finite Element Method. Pile response in terms of deflection, shear force and bending moments under vertical and horizontal loads from above three software are compared and concluded.

Sep 1, 2022

By W. Morgan NeSmith

A drilled displacement pile program was utilized for the expansion of an existing power plant in Cohasset MN adjacent to the Mississippi River. The drilled displacement (DD) pile is an innovative foundation type that provides exceptional value in some geologies. In the U.S., DD piles have typically been used in coarse-grained soils due to the large friction capacities that can be generated by the piles in these conditions. This project was the first large scale experience for the project team where it was anticipated that significant portions of the DD pile capacity would be developed in primarily fine-grained soils. The project site consisted primarily of variable amounts of fill overlying predominantly low plasticity alluvial silts. In some cases, alluvial silty sand layers were encountered within the expected pile installation depths. Alluvial sands were typically encountered below the silts, in some cases within the expected pile installation depths. The project team developed a probe and pile load test program to address the variable subsurface conditions across the site. The program included monitoring various parameters (including applied torque and tool penetration rate) during the drilling portion of the pile installation using recently developed data acquisition techniques. This data was used to estimate the rig energy, or Installation Effort (IE), required for pile installation. IE profiles from the test and indicator piles were compared with subsurface data available from a number of previous site characterizations. Additionally, Cumulative IE values were compared to an in-house database of IE vs. DD Pile Capacity. Final production pile toe levels were based primarily on IE values selected from this comparison. The IE data collected during production was also used to address large variations in pile-cutoff elevation (relative to a fairly uniform ground surface elevation).

Jan 1, 2008

By Richard Stone, Rouzbeh Afsharhasani, Moses Karakouzian

"Caliche, a hardened sedimentary deposit of calcium carbonate that occurs worldwide, generally in arid or semiarid regions, is frequently encountered in Las Vegas, Nevada. The presence of a caliche layer in a soil profile affects the response of deep foundations to axial load. This paper studies the stiffening effect of caliche layers on the elastic settlement of a pile foundation. In order to evaluate the response in a layered soil-caliche profile, finite element analyses were performed on a typical-sized single pile and a pile group, both having constant diameter and length of the pile. The results indicate that the stiffening effect from the caliche is noteworthy, and a layer with a relative thickness of at least one pile width, regardless of its location, reduces the pile settlement for both single piles and group of piles systems by at least 50%.IntroductionThe presence of cemented materials in the soil profile influences the settlement response of foundations. One type of cemented material that can be found in arid places around the world is a sedimentary deposit of calcium carbonate called caliche. Caliche, a hardened sedimentary deposit of calcium carbonate, is common in arid and semi-arid urban areas, such as Las Vegas, Nevada (Wyman, et al. 1993).Caliche is mostly observed in lacustrine, river, and alluvial fan deposits (Jr.C.C 1970). It is also found in Central and Western Australia, the Kalahari Desert, the High Plains of the Western U.S., and the Sonoran Desert of the U.S. and Mexico.Some conditions required for the formation of caliche are that country or basement rocks must be a carbonate type, carbonate must be present in the soil zone of the area, climate regime is semi-arid to arid, there exists widespread capillary activity, and carbon dioxide (CO2) is present in the environment. As a result, caliche occurs as a product of the carbonization process (Atabey, Atabey and Kara 1998). In such areas where foundations are constructed on thin rock layers (caliche), special geotechnical design conditions should be considered, particularly if the supporting rock layer is underlain by a weaker material."

Jan 1, 2015