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By Roberto Nova

The selection of the Osterberg Cell (O-Cell) technology as the standard testing method for deep foundations of the Railways Po Viaduct in Northern Italy offered a relevant number of field measures on large bored pile behaviour in alluvial soils. The assessment of pile response during such ?non standard? testing procedure was performed through the comparison with standard top load tests on companion piles as well as by numerical models of the tests including a simplified pile-soil interaction scheme. As shown in this paper, the O-Cell technology allowed a careful assessment of the non-linear pile behaviour even at quite small loading levels as those required by a posteriori proof tests on production piles. Simple numerical models proved to be very effective in the simulation and the interpretation of pile behaviour during such unconventional testing procedure.

Jan 1, 2008

By Eric Brandner

Expansive soil formations can be found throughout the United States. When subjected to wetting, many of these formations have the potential to swell and exert large uplift forces which can significantly damage lightly-loaded structures. Designing an economical foundation that can resist uplift forces is critical to prevent damage to these structures. The current solutions to control uplift due to swelling soils, such as over-excavation and replacement of the expansive material, or drilled shafts, can be costly and problematic. Piles made from recycled polymer materials may provide a solution. Due to a lower coefficient of friction along the interface than piles made from traditional materials, solid recycled plastic piles can allow expansive soils to move nearly independently from the pile when wetted. This results in a much smaller magnitude of uplift force being transferred to the structure which minimizes the risk of significant structural damage. This paper presents the preliminary results of research conducted on the use of recycled plastic piles in an expansive shale environment. The preliminary phase of the project involved the installation of six 13 in. (330 mm) diameter recycled plastic piles at a test site on the South Dakota School of Mines and Technology campus. The piles varied in length from 15 ft. to 25 ft. (4.6m to 7.6 m). Two of the piles were subjected to a full-scale compression load test in order to determine ultimate capacity, while the additional four piles are being subjected to long-term monitoring of uplift movement. A cast-in-place concrete pile, with a diameter of 6 in. (152 mm) and length of 15 ft. (4.6 m), was also installed at the test site for monitoring. The preliminary results indicate that the use of solid recycled plastic piles is a viable alternative for support of lightly-loaded structures in expansive soil environments.

Jan 1, 2009

By Frank Rausche

The more widespread use of Augered Cast-in-Place (ACIP) Piles has generated increased demand for improved quality control measures. These deep foundation elements are often relatively long and slender and their structural quality depends on the experience of the installers, the adequacy of their drilling and pumping equipment, and of course, the properties of the soil. Since the concrete of ACIP piles is pumped under pressure into the borehole, the piles may achieve a very high unit shaft resistance if conditions are favorable and the piles are well constructed. Three types of methods can help assure that the piles are properly executed. During construction, monitoring the volume of concrete pumped and the pressure applied helps avoid structural defects. After installation, and once the concrete has hardened, the Pulse Echo Method allows for a check of the structural integrity of the shaft. Finally, a load test, performed some time after installation, yields a check of both bearing capacity and structural integrity of an individual pile. Because of their expense and associated construction delays, static load tests are normally done for only a few piles. However, at large construction sites, it may be necessary to perform many load tests either as a planned construction control activity or as a means of spot checking or verifying suspect piles. For smaller sites, however, static load testing may be prohibitively expensive. In such situations, dynamic load testing, originally developed for driven piles, has frequently been employed for drilled shafts and ACIP piles. In the latter case special consideration must be given to the ACIP pile slenderness and their often relatively low concrete design strength, which may not tolerate high dynamic loading stresses even though their unit resistance along the shaft is relatively high. Lately, the dynamic load test has become more feasible with the availability of loading systems that are custom tailored to this particular pile type. These systems produce a low velocity, low stress and high energy impact. Recent developments have also made the instrumentation process simpler: force measurements are now made on the ram rather than on the pile for increased reliability and simplicity. This presentation describes the requirements for successful dynamic load testing of auger cast piles and summarizes results from several projects where the new loading system and newly developed instrumentation was employed. A few cases are presented correlating static load test results with dynamic predictions, calculated by CAPWAP®.

Jan 1, 2001

By Naoyuki Hanawa, Takeo Asanuma, Tatsuo Nagatsu, Sachihiko Tokunaga, Daisuke Nakagawa, Yoshiyuki Morikawa, Kazuhiko Ueno

"In the cement deep mixing (CDM) method, one approach to joint construction is creating a surface-contact joint. In this study, an unconsolidated-undrained triaxial compression test was performed on cement-treated soil specimens with joints artificially created by successive pouring. The effects of the presence or absence of such successive pouring joints on the strength of the specimens were then examined. The results showed that the compressive strength of the specimen decreased by approximately 0%–30% with a successive pouring joint.INTRODUCTIONIn the block type and wall type improvement patterns of the CDM(Cement Deep Mixing Method) application, an integrated body of soil-cement columns is constructed by partially overlapping individual treated soil columns. The overlapping operation should be implemented before the hardening of soils by cement progresses and thus, this operation is routinely performed in construction sites usually within 24 hours or within 48 hours at a maximum. However, when the operation is forced to be interrupted on account of a typhoon or any other adverse weather conditions, it is impossible to carry out the overlapping operation within the above time limitations. In such a case, it is necessary to improve the integrity between the treated soil columns solidified first and the treated soil columns to be constructed later.One of the methods that can be adopted is to prior agitate the target area by mixing blades “without cement”, integrating the preceding treated soil columns and the subsequently treated soil columns at construction joints. This method has been adopted so far in numerous sites because no additional materials or equipment are necessary. However, its effectiveness has scarcely been evaluated quantitatively in conventional studies.In the circumstances, the authors investigated in the present research the effect of the presence or absence of construction joints on the specimen strength by performing unconsolidated-undrained triaxial compression tests using specimens of cement treated soil artificially provided with surface-abutting construction joints.Therefore, this study examined the effects of the presence or absence of artificially created successive pouring joints on the strength of cement-treated soil specimens through an unconsolidated-undrained triaxial compression test."

Jan 1, 2015

By David S. Graham, Paul J. Axtell

Crosshole Sonic Logging (CSL) non-destructive integrity testing identified anomalous readings near the base of a 6.5-foot diameter drilled shaft rock socket. The anomaly was confirmed to be a defect by subsequent coring and core hole camera inspection. A large void and exposed rebar were visually observed in one of the core hole camera inspections. The center of the shaft was then excavated initially with 3-foot diameter tooling and subsequently with 4-foot diameter tooling as part of the remedial actions to address the defect. While excavating with 3-foot diameter tooling, the shaft defect was not encountered. Excavation with 4-foot diameter tooling revealed the defect, a significant void around the majority of the shaft circumference. The void extended radially from the circumference of the 4-foot diameter excavation to beyond the reinforcement cage to the exposed wall of the rock socket around approximately 80 percent of the shaft circumference. CSL results and observations made during remedial shaft investigation and excavation are in good agreement. The shaft defect, located primarily outside of the reinforcement cage, was effectively identified by CSL testing. Although the defect was confirmed by investigative coring, the remedial excavation demonstrates how the investigative coring could have easily missed the defect. This paper shows how CSL results compare to physical observations made during a rare opportunity to characterize the full extent and nature of a drilled shaft defect originally identified as an anomaly by CSL testing. INTRODUCTION The case history presented here pertains to a drilled shaft for a multi-shaft bridge pier in the Midwestern United States. However, the observations presented in this paper are not a result of unique site conditions or the particulars of the project. The lessons learned from this case history are applicable to almost any drilled shaft constructed in the wet. The overall length of the subject shaft is 22 feet including approximately 12 feet of permanently cased, 7-foot diameter shaft extending to bedrock and approximately 10 feet of uncased, 6.5-foot diameter rock socket. The shaft is designed to resist axial and lateral loads and considers the contributions of side and base resistance in the axial design. Six, 2-inch diameter steel Crosshole Sonic Logging (CSL) tubes are include in the shaft. The bedrock at the shaft location includes beds of sandstone, shale, and limestone. The shaft was drilled using conventional drilling equipment and tooling, and water was used as the drilling fluid. Conventional drilled shaft concrete appropriate for underwater tremie-placement was placed via a 10-inch diameter open hopper tremie.

Jan 1, 2019

By Kento Miyamoto, Kazuki Imamura, Takayuki Tanaka

"Global economic development has drastically increased energy consumption in various fields, and CO2 emissions, which are a prime cause of global warming, have continued to increase. Therefore, measures for reduction of the load on the environment have been taken in various areas. Energy improvements of various types of work vessels used for offshore construction might be expected to greatly reduce consumption of fossil fuel, because many of these vessels are larger than land construction machinery and consume large amounts of fuel, which will lead to effective use of resources and alleviation of the load on the environment. However, such efforts are unusual because renewal or newbuilding of work vessels is rare. We developed a work-vessel hybrid energy system based on fuel-saving technology and use of natural energy to promote reduction of CO2 emissions for a large deep mixing barge in 2010. We developed an Automated Generator Start-Stop System, which automatically controls the number of active generators according to power demand during ground-improving work of the deep mixing barge in 2012, thus further improving the work-vessel hybrid energy system. These systems are introduced here.INTRODUCTIONIn recent years, CO2 emission, which is one of the factors of the Global Warming has been increasing. According to the report by National Institute for the Environmental Studies in Japan (2014), CO2 emission in Japan has amounted to 1,276 million tons. The industrial sector in the total emission becomes 500 million tons that is equivalent to 39%. Meanwhile, the offshore Deep Mixing Method requires work vessels mounted with a large power plant (Fig. 1). In sea ground boring, very large load acts on the deep mixing machine, and the large power is required, which results in the increase in CO2 emission. To achieve eco-friendly marine construction, the work-vessel hybrid energy system was developed. Table 1 shows specifications of the deep mixing barge with the work-vessel hybrid energy system."

Jan 1, 2015

By Charles M. Wilk

"Mass stabilization involves mixing binding agents into marginal or contaminated soil to improve the subject material’s physical and/or chemical properties. This paper concentrates on the principles of soil mixing and benefits and application to new and existing rail right-of-way. Successfully applied in Scandinavia and other European countries, the soil mixing is now being applied in right of way in the northern latitudes of the U.S. and Canada. These regions have significant areas of “peaty” soils that can complicate construction and maintenance of rail and structure foundations. Mass stabilization can be used to improve the bearing strength of these soft soils for subsequent construction of railroads, pipelines, roads, and buildings. In civil engineering, the technology is often used to improve the construction properties such as bearing strength, of a marginal soil. In environmental engineering, stabilization is remediation treatment technology that protects human health and the environment by immobilizing hazardous constituents within the treated material. . The treatment is conducted while the subject material remains in-place (insitu). Mass Stabilization is often used to accomplish both civil and environmental purposes on the same project effectively addressing marginal soil while eliminating the expense of soil removal and replacement. This paper presents the principles of mass stabilization technology, implementation in the field and recent completed railway projects. The example rail projects will present the various benefits that soil mixing provides to railway construction and maintenance. Bench-scale studies and full scale implementation as well as soil construction properties before and after mass stabilization will be discussed. The paper and presentation will include information on the advantages of mixing methods and binding agent delivery systems.INTRODUCTIONNew or existing railroad right-of-ways may cross ground with low bearing capacity. Right of way subgrade undergo deflection (strain) as loads (stress) are applied. The amount of strain or deflection of the subgrade caused by loading of a train is proportional to the stiffness of the subgrade materials. Some soils, such as tamped ballast, are very stiff and resist loads well. Other soils such as soft clay, peat, or loose sand have low stiffness and undergo substantial movement under loads. It is very desirable to have the stiffest possible material in a track subgrade. Stiff subgrade material limits deflection under load, reducing track roughness and occurrence of track defects. Mass stabilization is a geotechnical method that can be used to improve the bearing capacity or stiffness of soil in these right-of-way. Mass stabilization involves mixing binding agents into soil subject to treatment while the soil remains in-place or insitu. Variations in the design or areas subject to treatment can be used to address transmission of vibration to adjacent structures."

Jan 1, 2015

By Y. W. Mou

In order to improve the construction of pile foundations and deep foundations of largo sizes, the paper deals with the method of installing square or rectangular bored-piles for annular foundation as well as large-sized hollow or solid foundation.

Jan 1, 2010

By M. Soranzo

This paper presents a restoration operation of the load-bearing capacities of a deep foundation which did not satisfy the original design conditions. The operation was preceded by a series of tests carried out after construction of the pile foundation. In order to verify the efficacy of the method, both load tests on piles before and after intervention and tests on the material used in underpinning the piles were carried out.

Jan 1, 2010

By H. Mori

This paper describes a new borehole loading test using a self-boring instrument appropriate for dense sandy soils and stiff clayey soils. The results of loading tests for the bearing strata of deep foundations according to this method are also presented. This method has been applied to the study on the settlement behavior of heavy foundations resting on dense sand, stiff clay or soft rock in Japan.

Jan 1, 2010

By P. Srinivasulu

The popular theoretical models used for assessing the dynamic behaviour of piles under vertical and lateral excitations are critically reviewed. An experimental study is presented on model piles with varying slenderness ratios. The theoretically evaluated and experimentally deduced natural frequencies and resonant amplitudes of the test pile-soil system are compared. The dynamic stiffness and damping are seen to increase with increasing slenderness of piles. Further, the damping yielded by the theory is found to be on the unconservative side.

Jan 1, 1996

By D. A. Ponniah

The installation of a pile is considered analogous to the expansion of a cylindrical cavity of a diameter equal to that of the pile. Using Vesic's theory of the expansion of cavities the effect of soil properties on pile installation loads, radial pore and total pressures are evaluated. The theoretical results are compared with load and pressure measurements made in field trials in a stiff clayey glacial till in the U.K.

Jan 1, 1987

By L. J. Whitworth

Five trial piles were constructed during the trial pile programme for the Birmingham International Convention Centre. In addition, trial piles have been tested on two other sites in central Birmingham. Methods of pile construction were conventional sandstone rock sockets, sleeved piles and voided piles. The results of these load tests are compared with the theoretical predicted behaviour based on the results of unconfined compressive tests of rock core taken on the Convention Centre site and on other sites in the central Birmingham area. On the basis of this work, the various design procedures are discussed.

Jan 1, 1989

By W. H. Craig

Techniques have been developed for installing model piles into beds of soil under high sustained acceleration levels aboard a centrifuge. These piles have been subjected to static and/or cyclic lateral loading in order to assess their performance and provide a data base for assessment of various design techniques for laterally-loaded single piles. From measured bending moment profiles the so-called 'p-y' curves have been deduced using fifth order splines for curve fitting, followed by subsequent differentiation and integration. The results show some divergence from the predictions of the semi-empirical designs, but these latter are generally found to be acceptable.

Jan 1, 2010

By A. Le Kouby

We present in this paper the results of a parametric study carried out in a calibration chamber on instrumented model piles. The aim is to point out group effect on piles within a group through their resulting shaft friction and tip resistance. The methodology relies on the study of the influence of adjacent piles on a "reference" pile. The soil used is a silica sand (Fontainebleau sand). The influence of parameters like pile spacing, number of piles and installation order are evaluated. The results show a positive effect on shaft friction of the group effect and a negative effect on tip resistance. Efficiency factors are defined in order to have a better view on the parameters influencing the response of the pile within a group.

Jan 1, 2006

Caissons hand dug to a depth of about 100 feet were used to underpin three important structures at an industrial site in the State of Utah. The caisson shafts extended through 30 to 40 feet of coarse, granular soils and 25 to 60 feet of sands and clays to bear on a very dense, coarse gravel and cobble stratum near the water table. The shafts were belled to 12 feet square at their bearing elevation. Bearing pressures of 20 ksf were assigned. The shafts were lagged with timber. The use of hand-dug caissons allowed continuous operation of the facility during underpinning. Settlements after underpinning have been minor and well within the estimated magnitudes. Instrumentation was placed in two of the caissons with varying degrees of success.

Jan 1, 2010

By R. Chowdhury

The relevance of reliability studies for deep foundations is considered in this paper with special reference to pile foundations. Attention is drawn to uncertainties related to applied loads, the load-carrying capacity and the safety margin of a pile foundation. The essential steps in a reliability study are outlined. An essential goal of any study is the determination of the Reliability Index or Safety Index under different conditions of loading and operation. Calculations concerning probability of failure or success require an assumption to be made concerning the probability distribution of the safety margin. The significance of this and other assumptions should be clearly understood. Reliability approaches should be used to complement conventional deterministic studies.

Jan 1, 2010

By I. K. Ozaydin

Analysis of piles groups loaded with large bending moments and both vertical and batter piles can be best performed by matrix analysis. In this paper, a case history about a tall marine control tower is presented. The soil conditions at the site and the results of the computer analysis of the piled foundation are summarized. It is shown that the pile loads are indeed less than the allowable load for a single pile. Pile head loads and moments are used in the analysis of the raft foundation.

Jan 1, 2010

By D. E. Sherwood

Twelve toe grouted, and eleven ungrouted piles, founded in very dense sands have been analysed to establish how toe grouting enhances pile performance. It is shown that pile stiffness is greatly increased, and that pile bases work effectively. This is in contrast to ungrouted piles, where some milli­meters of base movement may be required before the base is mobilised. Grouting appears to recover most of the disturbance caused during construc­tion, but in general does not enhance the ultimate bearing capacity of undisturbed ground.

Jan 1, 1989

By Anand J. Puppala

This paper provides information on various evaluation studies conducted to assess the CPT based interpretation methods. Salient findings from these evaluations are summarized. Additionally, a comprehensive evaluation study on both LCPC and European methods was performed on twenty-four driven piles selected from four different states. This evaluation showed that the LCPC method predictions are close to measured pile capacities. The European method provided good predictions for driven steel piles. Overall, both methods' predictions show high values of coefficients of variations, which are in agreement with other studies. Overestimation of driven concrete pile capacities is attributed to large estimations of unit point resistance. Suggestions to consider appropriate CPT based pile capacity interpretation methods are presented.

Jan 1, 2002