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By Philip Derbyshire, Dale J. Scheffler

"Continuous Flight Auger (CFA) piling is a variation of Augered Cast-In-Place (ACIP) or augercast piling. In both cases a continuous auger with a hollow stem is used to drill a hole and a pile is formed by injection of cementitious material through the hollow stem as the auger is withdrawn. CFA differs from conventional American ACIP by the use of concrete rather than grout to form the pile, and by the type of equipment used to advance the auger into the ground and withdraw it. CFA installation uses a European style rig (i.e. fixed mast and rotary system) which can produce greater crowd and usually has a larger rotator or drill motor than the standard augercast setup. A standard augercast setup will consist of a lattice-boom crane and a set of leads to house the drill motor and auger. The auger size will range up to 24 inches (610mm). With CFA rigs larger diameter piles can be constructed, 24 to 36 in dia. (610mm to 915mm) are common and the technique has been applied with diameters up to 48-inch (1220mm). CFA makes use of sophisticated computer controlled monitoring systems, which have more recently been introduced for conventional ACIP piling. Developments in CFA have taken place over the last 25 years in Europe and particularly in the UK, but are relatively new in the USA. One application is in the construction of secant (overlapping) piled retaining walls. D.J. Scheffler Inc. recognized the potential of the CFA system following visits to the UK and has introduced its use into California for both secant piling and other applications.BACKGROUNDThe high price of real estate in many of the favored areas of California has increasingly led owners to want to build basements under their houses to increase the floor space available on a lot. Many of these areas are by the coast where the ground conditions are predominately granular and the water table is high. Conventional shoring and dewatering systems have often caused problems with adjoining properties. Clearly tangent walls are not suitable in these conditions because of leakage and loss of ground. The secant pile system, using CFA techniques, has proved very effective at overcoming the problems experienced by other methods. Other applications for CFA secant walls have included use for an emergency job on a highway following erosion caused by unusually heavy rainfall.METHODThe concept of secanting piles, whereby primary(female) piles are installed first and then secondary (male) piles are cut into the primary piles is not new. The method has been known for more than 30 years. Originally ‘Benoto’ grabbing rigs, developed in Japan, were used together with sectionalized double skinned casing and oscillators.This early method was slow, although very effective. More recently high torque rotary machines have been used. Contractors in the UK have increasingly used CFA techniques to further improve productivity of this type of piled wall. The improved capabilities of piling rigs available, as well as developments in concrete technology and instrumentation, have made this possible."

Jan 1, 2005

By Tomio Tsuchiya

A construction method of bored steel H piles enclosed in soil-cement columns was developed by modifying steel H piles from the driven pile method and soil-cement walls from the earth retaining wall method, the latter of which produces cut-off walls and reduces noise and vibration during construction. In this method, as shown in Figure 1, rich mix cement paste is injected into the bottom of a borehole which is pre-excavated by a casing auger, then a steel H beam is inserted before it hardens. Since the high vertical resistance of piles created with this method has already been confirmed by loading tests, we have been investigating the applicability of this method for piles used to temporarily support building loads for top-down construction on raft foundations until the raft foundation is completed. However, in the loading tests, the bearing capacity at the lower end of the pile was measured by loading from ground surface on test piles which had friction cut to eliminate the shaft friction resistance. In other words, the loading tests neglected the effect of overburden pressure of soil above the lower end of the pile. To investigate the effect of the overburden pressure on the bearing capacity at the lower end of the pile, loading tests were carried out on a bored steel H pile of lm diameter (test pile) bored in a compacted sandy soil layer with N-value of 100 to 250 at each stage of a three-step excavation. The results show no significant change in the bearing capacity at the lower end of the pile when the depth ratio of the pile is in the range of 5.7 to 22.7.

Jan 1, 1996

By K. E. Darnell

Drilled pier foundations have long been a favored foundation type for heavily loaded structures. Drilled piers derive their load-bearing capacity from end-bearing, and/or sidewall friction. This type of foundation is used in many geologic settings, including those areas underlain by hard carbonate rock, such as limestones and dolomites. When properly designed and constructed, drilled piers provide high load-carrying capacity in both compression and uplift. However, carbonate rock is often subject to intense differential weathering resulting in the formation of an irregular bedrock surface, sinkholes and caves; consequently, the investigation for, and the design of, drilled pier foundations is often complex. Further, the construction may be difficult and costly. This paper discusses geotechnical investigative procedures which can be employed to develop foundation design criteria and reduce the frequency of changed conditions. Finally, state-of-the-art construction practices and quality control techniques are discussed.

Jan 1, 2010

By Dennis Nottingham

The need for deep compaction of submerged granular soils has led to improvements in this area. In 1971, L.B. Foster Company personnel patented a method of deep compaction using a vibratory pile hammer and pile probe. The technique had some success, but did not produce consistent results and thus found its way to obscurity. Other patents attempted to modify the technique by various probe modifications, but again without measurable improvement from a practical point of view. Solutions to economical deep compaction up to 100 foot depths particularly in saturated granular soils would have a great impact on the construction industry and new bulkhead structures being developed, thus PND was prompted into related research and development. The advent of higher horsepower vibratory hammers, coupled with PND engineers? experiments, observations and measurements, led to an ?H? pile probe design which has produced measured soil density improvements up to 250% using SPT ?N60? values as a measure.

Jan 1, 2013

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

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

Jan 1, 2015

By Jerry A. Steding

How many times have you heard "You can't drive piles because of the vibration."? You hear these words come out of the mouths of owners, engineers, and contractors. When a piling contractor hears this, he can almost always do a psychological profile of the individual uttering these words of wisdom. If the owner makes the statement, we know the odds are about 95% that the owner owns the building next door or he wouldn't care what happens to it; or the guy next door has threatened to sue the owner if he even so much as walks across the site of the proposed new building. If the owner owns the building next door to the new construction you can also be just as certain the old structure has undergone settlement. If the statement comes from the mouth of the contractor, it is usually just a case of him being inexperienced.

Jan 1, 1988

By Ross T. McGillivray, David S. Graham, Dan A. Brown, Steven D. Dapp

"The Selmon Expressway includes an elevated structure extending across several miles of weathered karstic limestone geology, and represents a challenge for design because of the high variability of the material and the difficulty in characterizing the strength. The nature of the epikarst in this region of Tampa is such that variability can be extreme within distances of only a few feet. The weathered rock includes extremely soft soil infill within solution features on and within the formation. The limestone is so weathered that coring typically does not yield useful samples for strength testing, and in-situ Standard Penetration Testing (SPT) tests often encounter refusal blow counts. Thus the challenge for foundation design includes two components of reliability risks: the uncertainty associated with the ground conditions at a given foundation location plus the uncertainty associated with the foundation performance at a given location even when the stratigraphy is determined.This paper describes the design approach that has been implemented successfully for two projects at the Lee Roy Selmon Crosstown Expressway (LRS) in Tampa, Florida: the assessment and remediation of the reversible elevated lane (REL) foundations constructed in 2004, and the elevated expressways widening project constructed in 2012. Included in this design approach is a method developed for computing axial resistance in this local geology. Design for axial loading relies primarily on the development of side resistance, which was considered less subject to performance risks than base resistance. The calculation method incorporates a statistical analysis of SPT data, tempered by engineering judgment, to characterize stratigraphy at a given location into either soil, intermediate geomaterial (IGM) or rock.IntroductionThe subsurface stratigraphy of sites underlain by weathered limestone formations can be highly variable with respect to material layer thicknesses and strengths, even over short horizontal distances. This is the case for much of Florida, and particularly the Tampa area. These conditions present a challenging environment for the design of drilled foundations because of the need for a reliable determination of subsurface conditions at each foundation location, as they relate to the expected axial performance. Contributing factors include:"

Jan 1, 2015

By Anne Lemnitzer

Experimental data are the cornerstone of scientific research, providing empirical evidence to validate hypotheses, test theories, inform decision-making and help develop innovative design and analysis methods. However, beyond traditional empirical validations, experimental data have also become the most crucial component of AI algorithms, measuring the algorithms' effectiveness, and allowing engineers to ensure their reliability and applicability. The DFI "Rock Socket Project," awarded in the spring of 2018 allowed for the indispensable, experimental data-based validation of structural shear magnitudes, which have been hypothesized and discussed for years within the deep foundations community and cautiously approached by many design engineers. The fundamental project idea, i.e., the investi- gation of pile shear magnitudes through experimental research, was sparked during a heated discussion in the October 2016 Drilled Shaft Committee meeting in New York. Should we design for amplified shear at the rock socket of a drilled shaft or is this merely an artifact of the p-y design approach? Data were needed to provide consensus.

Nov 1, 2023

By Kazunori Matsushita, Masaru Sakakibara, Kenji Harada, Naotoshi Shinkawa, Mitsuo Nozu

The Sand Compaction Pile (SCP) method has been widely used as a typical countermeasure against liquefaction in Japan, and its effectiveness has been confirmed in many case histories of damages caused by the past large-scale earthquakes. A series of studies were conducted to evaluate the effectiveness of the compaction method and other factors, if any, in sustaining a seismic force that is greater than the assumed one and caused no damage. Based on the results of these studies, the Architectural Institute of Japan (AIJ) has indicated in its “Recommendations for Design of Ground Improvement for Building Foundations” published in 2006 that the liquefaction resistance ratio (tl/sz) of the composite ground, which consists of sand piles and surrounding compacted ground, is higher than the RL calculated by using the SPT N-values of the ground in-between the sand piles. In this paper, statistical analysis of safety factor against liquefaction, FL, was performed by using the SPT N-values of ground in Port Island and Rokko Island which were both fully reclaimed islands in Kobe city during the 1995 Hyogo-ken Nambu Earthquake (classified as intense shaking) and, together with the consideration of relative settlement, resulted in tl/sz of the composite ground being 1.5~2.5 times of tl/sz of the soil in-between piles after improvement. Furthermore, the liquefaction resistance curve of SCP-improved sites obtained from the relationship between SPT N-values and cyclic shear stress ratio during the 2011 off the Pacific Coast of Tohoku Earthquake, which was regarded as long-duration earthquake, was plotted to the left side of the curve originally proposed by Japan Road Association. Thus, the liquefaction resistance of the improved ground was found to be higher than that of the natural ground, even for the same SPT N-values, verifying the validity of the AIJ recommendation.

Jan 1, 2017

By Thomas L. Vande Voort

The strategic plan for bridge engineering issued by AASHTO in 2005 identified extending the service life and optimizing structural systems of bridges in the United States as two grand challenges in bridge engineering, with the objective of producing safer bridges that have a minimum service life of 75 years and reduced maintenance cost. Material deterioration was identified as one of the primary challenges to achieving the objective of extended life. In substructural applications (e.g., deep foundations), construction materials such as timber, steel, and concrete are subjected to deterioration due to environmental impacts. Using innovative and new materials for foundation applications makes the AASHTO objective of 75 years service life achievable. Ultra High Performance Concrete (UHPC) with compressive strength of 26,000 psi (180 MPa) and excellent durability has been used in superstructural applications but not in geotechnical and substructural applications. This paper explores the possibility of using precast, prestressed UHPC piles in future bridges. An H-shaped UHPC section, which is 10-in. (250-mm) deep with weight similar to that of an HP10×57 steel pile, was designed for constructability and economical reasons. Instrumented UHPC elements were cast to conduct large-scale field tests. In the field, two UHPC piles have been successfully driven in glacial till clay soil and load tested vertically. Test results, durability, drivability, and other material advantages over normal concrete and steel indicate that UHPC piles are a viable alternative to extend the life of bridge structures.

Jan 1, 2008

By Jack Hayes

The design and construction of deep foundations involve many uncertainties. For the designer there are uncertainties regarding soil and ground water variability, regarding sampling and lab testing, regarding analytical techniques and regarding construction technique. The latter being the uncertainty over which the engineer has least control and which may have the greatest impact on capacity. Foundations with a high design factor of uncertainty can be very costly. Foundations designed with a high factor of uncertainty may have a low factor of safety, which can be even more costly.

Jan 1, 2000

By G. W. Plant

This paper describes the design philosophy and construction details of piles between 25m and 32m deep to support 160m high and 110m base diameter cooling rowers for a major power station. It is sited on deep expansive soil where a vast plantation of Eucalypts had been felled. The depressed water table is expected to rise, leading to swell of the soil and uplift forces on the piles. These forces, combined with the complex loading from the cooling towers, led to design tensile loads up to 20MN (2 000 tons) per pile. When competent stable material was present hand excavated underreams 3m in diameter were constructed for the piles sup-porting the shells. However, in some areas it was not possible to form an effective underream and an innovative solution was sought. This comprised unstressed dowels in the underlying sandstone which were formed by percussion drilling through void formers cast into the piles.

Jan 1, 2010

By Garland Likins

High strain PDA testing has become common for verification of capacity of both driven and bored piles. It is equally applicable to Augered-Cast-in-Place (ACIP) Piles. It also evaluates other aspects of the installation such as integrity. The benefit of high strain dynamic test results for the relatively low cost of the tests compared to conventional static testing has resulted in widespread use. The method is described and specific procedures for testing ACIP piles are outlined. Example results demonstrate the application.

Jan 1, 2000

By C. O. Riggs

Geotechnical exploration in North America, in particular, exploration for deep foundations analyses, is currently and generally performed following the most basic sampling and insitu testing methods and techniques. Some would surely say that the state-of-practice severely lags the state-of-the-art. Probably more than 90% of all deep foundations, both driven piles and drilled piers, installed in North America are initially analyzed and designed, i. e. geotechnically, on the basis of either the soil penetration resistance obtained by performing the "Standard Penetration Test" (SPT), or from laboratory shear tests performed on samples obtained using 76-mm (3-in.) nominal diameter, thin wall, "Shelby tube" samplers. The use of design data obtained with other exploration methods and devices, such as bore hole pressure meters, flat plate dilatometers, even cone penetrometers, occur on the fringes of practice and often in conjunction with the use of the two simpler methods of analysis. This basic approach probably represents an attempt of the profession to use, as much as possible, common, easily understood and easily communicated procedures in all geologic environments. The characteristics of drill rigs with the required drilling and samplng tools vary somewhat from region to region in North America according to the physiography of the area of use, the types of exploration data required on a day-to-day basis, the philosophy of the engineers and geologists that use the exploration data and the financial resources of the drill rig owner. The physical capability of the exploration drill rig used on a project can have a significant effect on the quality of samples or insitu tests. The physical configuration and the quality of the drill and the drilling, sampling and testing tools not only provide the mechanical capability to obtain data but affect the attitude of the field exploration crew and the quality of work. This complete presentation is taken, for the most part, from a book in preparation for publication: "Geotechnical Exploration and Site Characterization" by C. Riggs, A. Hatheway and N. Schmidt. The book is scheduled for completion during 1987.

Jan 1, 2010

By Tsuyoshi Honda, Kazuhiro Kaneda, Masayuki Imai, Kazuo Konishi, Kunio Higashinaka

"In recent years, the demand for measures to control liquefaction of existing airport runways and harbor structures has increased. However, from the perspectives of constructability and cost, application of grid-form deep mixing walls to these types of structures requires the formation of wider grid spacing as compared with conventional designs. In this research, we focused on the extent of liquefaction and ground surface settling when grid spacing is made wider than conventional designs. We conducted centrifuge model tests, and confirmed the liquefaction suppression effect when grid-form modifications involving wide grid spacing are adopted under asphalt pavement. The tests were conducted under conditions that included changing the grid spacing and groundwater level. When the groundwater level was high, an increase in water pressure was observed, even within the grid. However, when the groundwater level was low, the increase in water pressure inside the grid was suppressed. We also found that if the generation of water pressure can be suppressed, the amount of settling due to liquefaction can also be controlled.INTRODUCTIONOne construction technique used as a countermeasure to liquefaction is grid-form deep mixing walls. Grid-form deep mixing walls are a construction technique for which improved grid-shaped wall bodies are built into the ground below the surface using a deep mixing method. This construction technique minimizes shear deformation by surrounding liquefied ground with improved wall bodies, thereby preventing liquefaction (Fig.1). With conventional designs, grid-form deep mixing walls determine the grid spacing that can deter liquefaction based on a ratio of the grid spacing L to the improved depth H (ratio = L/H). Ordinarily, designs are implemented with an L/H ratio of 0.8 or less (PWRI, 1999).In recent years, a demand for measures to control liquefaction of existing airport pavement and harbor structures has increased. However, when liquefaction countermeasures are implemented at these types of facilities and structures, the construction work must be implemented while the facilities and structures remain in service. Therefore, temporal and spatial constraints must be considered. In addition, unlike conventional liquefaction countermeasures, performance requirements are such that, even if some degree of liquefaction is allowed, the performance is acceptable as long as the amount of settlement is within a predetermined value. Therefore, if grid-form deep mixing walls are applied to these structures, grid spacing that is wider than conventional standards is desired."

Jan 1, 2015

By Paul M. C. B. M. Cools, Martin Th. van Staveren

In 2010, the 5-years joint industry programme Geo-Impuls started in the Netherlands. The ambitious goal of this programme is to reduce geotechnical failures in our civil engineering projects by half in 2015. In the Geo-Impuls programme over 40 client organizations, engineering firms, contractors, research institutes, and universities are involved. In a risk-driven way, and based on top risks and dilemmas, the participants defined three central development themes. These themes are (1) contracts, for dealing with legal issues, (2) geo-engineering, for dealing with technical issues, and (3) communication, for paying attention to differences in risk perception by the human factor. In total 12 Working Groups contribute to these themes by producing one or more specific tools. These provide practical solutions for how to deal with contractual, geotechnical, and communication issues. The tools include working processes, guidelines, best practices, as well as some instruments. The development of these tools, as well as the available results, will be presented in this paper. From the start, Geo-Impuls embraced geotechnical risk management (GeoRM) as the risk-driven way of working for geotechnical engineering and construction. Over the past years, GeoRM and its supporting tools were already successfully applied in several projects. Therefore, the paper also describes also the GeoRM implementation process, including the quality assurance and control. Finally, the effectiveness of GeoRM will be discussed, by summarizing an analysis of all published geotechnical failures and accidents in construction projects in the Netherlands, which decreased substantially over the past 4 years.

Jan 1, 2017

By G. Ranjan

The designers and the practicing engineers have started using latest and cost effective techniques of ground improvements which utilise the weak and poor sub-soil deposits efficiently for the civil engineering construction. In the present investigation, a new concept of 'skirted granular piles' has been advocated. An effective method of construction of granular piles as an economical alternative to vibroflot, and the skirt has been developed. The construction technique is based on indigeneous know how which effectively utilises the man-power technology avoiding import of costly equipment suiting to the developing countries. Full scale insitu tests have been carried out at four sites, having different soil conditions, on virgin weak sub-soil, and improved ground by casting plain and skirted granular piles. Effectiveness of different types of skirt has been demonstrated through insitu tests. A simple analytical approach has been proposed to predict the ultimate pile capacity. The predicted values of ultimate capacity have been found to demonstrate a good correspondance. Granular pile behaviour in terms of pile depth, diameter, spacing and stress deformation characteristics of the improved ground have been discussed. A significant improvement in ultimate capacity in improved ground has been noted. This is further augmented when granular pile group is skirted.

Jan 1, 2010

By Richard E. Sylwester

Evaluating surface and subsurface conditions for marine foundations (bridges, causeways, terminals, etc.) is often done with a limited amount of data. Subsurface information for these projects is primarily acquired using traditional methods, such as boreholes, test pits or divers, which tend to be expensive and limited in the area of coverage. A number of geophysical methods, including precision bathymetry, sidescan sonar, and seismic reflection or subbottom profiling are extremely cost-effective and obtain significantly more data than can be acquired using traditional intrusive methods. These geophysical methods provide detailed surface images and continuous profiles of the subsurface stratigraphy. This information can be invaluable for selecting the best location for geotechnical boreholes and to map potential geohazards such as submarine slides and filled or open scour holes. Offshore investigations conducted for a proposed highway bridge (Knik Arm Bridge, Cook Inlet, AK), the retrofit of two existing bridge (Antioch and Dumbarton Bridges, CA) and a proposed cruise ship terminal (Ketchikan, AK) used a combination of geophysical methods to map water depth, detect and map debris on the seabed, map the thickness of unconsolidated sediment, determine the depth to bedrock and identify potential geohazards such as scour holes. The results of the geophysical investigations will be used to select locations for obtaining geotechnical borings, to extrapolate geologic information between existing or proposed boreholes, evaluate the potential depth of scour and design a pile support pier. Geotechnical engineers, offshore contractors and bridge designers are realizing the importance of the early use of offshore geophysics for (i) site characterization, (ii) to reduce the uncertainty of geotechnical conditions thus avoiding designs that may be overly conservative and thus more expensive and (iii) to assist in selecting locations for geotechnical borings.

Jan 1, 2013

By Terry Eldridge, Keith MacKay, David Siddle, Luke Moger

On August 4th, 2014, a breach occurred in the Perimeter Embankment of the Tailings Storage Facility (TSF) located at the Mount Polley Mine, releasing approximately 10.6 million m3 of supernatant water, 7.3 million m3 of tailings solids, 6.5 million m3 of tailings interstitial water and 0.6 million m3of construction materials. A Temporary Upstream Rockfill Berm was constructed between August 2014 and February 2015 within the area of the tailings dam failure in order to retain the remaining tailings solids during the low flows of the winter season. The Temporary Upstream Rockfill Berm was constructed as part of the initial response phase, with the primary objective to abate the flow of tailings into the receiving environment. A secondary objective of its construction was facilitating the required investigation works downstream of the tailings dam failure. The selection of the coarse grained material used in the construction of the Temporary Upstream Rockfill Berm was based on the availability of the material (timeliness of construction) and the non-water retaining design of this initial response phase. Consequently, an alternative method was required in order to prevent further loss of mine-affected water and tailings from the TSF, as well as to provide short-term contingency water storage, during high flow conditions expected in late spring. Golder Associates Ltd. designed the 2015 Freshet Management Embankment, a deep mixing cut-off wall, to meet these site requirements, which was constructed by Mount Polley Mining Corporation and Golder Construction Inc. between December 2015 and April 2015. The works included 132 soil cement panels constructed to depths of up to 27 meters. This aspect of the works was completed using an RG25S Bauer CSM rig on a 24 hour per day, 7 day per week schedule. The cut-off wall specifications included a target unconfined compressional strength (UCS) of between 1 and 2 MPa, a maximum hydraulic conductivity of 1x10-6 cm/s, and a ductility to enable the soil cement to undergo a minimum of 5% strain without a reduction in strength or increase in hydraulic conductivity. In order to control and assure the quality of the soil cement, 2553 wet grab specimens were retrieved from the fresh soil cement panels using a project-developed sampler. Four of the soil cement panels were cored with a mud-rotary drill rig and optical and acoustic televiewers were placed into the boreholes in order to log several relevant parameters, including image, texture, relative hardness, borehole-shape, and temperature.

Jan 1, 2016

By Ke Yang, Robert Liang

"Drilled shaft foundations are widely used for many types of structures, especially for highway bridges, high rise buildings, and costal structures. The lateral design considerations are crucial for those structures that are subjected to lateral thrust forces, winds, waves, and earthquakes. The p-y analysis is the most widely used method for the analysis and design of drilled shafts for lateral load applications in soils. However, existing p-y criteria were developed based on the lateral load tests on small diameter drilled shafts in soils. Although, a lot of lateral load tests have been conducted, there are a limited number of lateral load tests on large diameter drilled shafts embedded in clay. In this paper, a lateral load test on 2.44 m diameter fully instrumented drilled shafts in clay is presented. The site specific p-y curves are derived based on strain gage readings. The existing p-y curves are found to be much softer than the site specific p-y curves. Correspondingly, the deflection at the top of the test shaft under the maximum applied load is predicted to be eight times larger than the measured value using existing p-y criteria. A new p-y criterion is proposed in this paper. The proposed p-y criterion is proven to be able to capture the site specific p-y curves of the load test and to predict closely the deflections at the top of the test shaft. INTRODUCTIONDrilled shaft foundations are widely used for many types of structures, especially for highway bridges and costal structures. The lateral design considerations are crucial for those structures that are subjected to lateral thrust forces, winds, waves, and earthquakes. Although efforts have been made on studying lateral response of drilled shafts; nevertheless, only limited studies have been published on the behavior of large diameter drilled shafts under lateral loads and the corresponding design methods."

Jan 1, 2005