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By Andreu J. Ferrero

Polyurethane and acrylate resins are routinely injected into soils to gain strength and control water flow. However, most published data regarding strength gain is derived from laboratory samples created under ideal conditions. This study endeavored to inject resins into full scale mock-ups that could then be excavated and tested to yield results comparable to actual field conditions. To achieve this goal, a large container was filled with a silty SAND (SM), as defined by the Unified Soil Classification System (USCS). The soil was moisture treated and compacted in lifts of 0.3m. PVC pipes installed in a diamond grid into the soil were used to inject polyurethane and acrylate resins. Dynamic cone penetrometer (DCP) tests were conducted on the polyurethane treated soils, the acrylate treated soils, and the baseline untreated soils in the container. Testing results will be correlated to SPTn and CBR values to evaluate increases in the soil strength parameters in the treated soils. Cored samples of polyurethane and acrylate treated soils will be tested in compression, shear, and triaxial. These laboratory test results will focus on material property gains for the treated soils, in comparison to standard values for similar soil types. Complete documentation of the soil type, compaction methods, injection methods, and testing performed have been documented and will be presented in the final paper.

By Sung-Ryul Kim, Woong-Jong Park, Juhyung Lee, Si-Hoon Lee

"A bucket foundation has been considered to be a potential foundation technology for offshore wind turbines. In this study, a series of 1-g model tests were performed to analyze the accumulated rotation of suction bucket foundations under long-term cyclic horizontal loads. The model suction buckets were made to have the embedment ratios of 0.5 and 1. The dry model ground was prepared to have two different soil densities by air-pluviation method. A horizontal cyclic load over 104 cycles was applied varying the loading amplitude. Test results showed that the accumulated rotation of the bucket foundation increased with the increase in the number of cycles and load magnitudes. Based on the model test results, a new equation was proposed to evaluate the accumulated rotation of the bucket foundations in sandy ground under long-term cyclic horizontal loads.INTRODUCTIONRecently, a bucket foundation has been considered to be a potential foundation technology for offshore wind turbines. In terms of economy, a bucket foundation has been considered to be an economical foundation type at sea beds where ground condition is clay or medium dense sand.A bucket foundation resembling a bucket is a kind of suction-installed foundation units. It is a skirted steel foundation which is open at the lower end and closed at the upper end by a lid. The embedment depth ratio (L/D) of a bucket foundation is usually less than one. Figure 1 shows an example of a bucket foundation. Offshore wind turbines are subjected to long-term cyclic loading by wind or currents. A bucket foundation is installed in soil grounds, so the long-term cyclic loading may induce the accumulation of soil deformation.In this study, the accumulated rotations of the bucket foundations in sandy ground were investigated under long term cyclic horizontal load. The number of cycles up to 104 cycles was applied varying load magnitude. The accumulated rotations of the bucket foundations in sandy ground were analyzed based on the test results."

Jan 1, 2016

By S. P. Lin

The numerical models of nonlinear piles for deep foundations are studied in this paper. The purpose of these is to clarify the mechanical behaviour of deep foundation nonlinear piles subjected to axial and lateral loadings. Based on the site data of p-y curve as well as t-z curve of foundation soils, it is possible to evaluate pile performance under above mentioned loads by means of combined FEM/FDM models. Numerical examples are presented in tall building and offshore jacket for illustrating the technique, it show high efficiency of these models. Some information to be interested by design engineers are given, especially for those who pay very concerns on the interaction behaviours of structure and its pile foundation.

Jan 1, 2010

By Kazuyoshi Kamimura, Masaya Kawata

"It has been 30 years since the cement deep mixing (CDM) method developed in Japan. CDM method has been applied to many structures. While various technical improvements have been implemented in the meantime, the single-axial and double-axial technologies used at the time of its initial development are still prevalent.In response to the recent trend of reducing construction costs, we developed a triple-axial CDM method called the “Lemni 2/3 Method.” This method uses two lemniscate motions caused by newly developed auxiliary stirring devices and employs a double-axial injection method in which the cement slurry injection takes place only from the outer two axes. In this way, it is possible to create a stabilized body around the three axes. Moreover, this method does not require substantial equipment investment as conventional construction machine and facilities can be used without modification and large volume work is possible.With these technologies, this method can achieve a substantial reduction in the construction period and cost, while ensuring the same level of improvement quality as conventional methods. As a result, this method is being applied to ground improvement work in a variety of places.Lemni 2/3 Method was first put to practical use in 2004. Since then, the method has been used for ten projects. In this paper, we show some application examples of this method.OUTLINE OF TRIPLE-AXIAL CDM METHOD (LEMNI 2/3 METHOD)In the newly developed CDM method (Lemni 2/3 Method), work efficiency is improved by employing triple-axial stirring blades instead of the conventional single- or double-axial type. Existing conventional construction facilities for double-axial type can be used with only minor equipment additions, because the cement slurry injection takes place only from the outer two axes.Construction Machine and Construction MethodThe combination of major construction machines of the Lemni 2/3 Method differs little from the standard specifications of the double-axial type as shown in Fig. 1. Existing work control equipment can be used without modification, which is further evidence of the simplicity, convenience, and economy of the new method. The Fig. 2 photo shows a full view of the construction machine, and the Fig. 3 photo shows the stirring blades and the auxiliary stirring devices. The work procedure for the Lemni 2/3 Method is shown in Fig. 4."

Jan 1, 2015

By Jr NeSmith

"Drilled Displacement piles are a product of screw pile technology originally developed in Europe. The process involves rotating tool into the ground that displaces the soil laterally as it advances, then grouting or concreting through the hollow stem of the tool as it is withdrawn. They were first introduced in the United States in the 1990’s and have become a mature and accepted technology since that time. They are now used to support a variety of heavily loaded structures including electric power and LNG facilities, stadiums and arenas, airports and mid- to high-rise commercial and residential facilities. In urban environments, the technique has a number of advantages including, low noise and vibrations, no removal of the existing soil, and reduced pile material cost due to the improved stress state of granular soils after installation (smaller or shorter piles can be used). For these reasons, displacement piles have been used to support various facilities in Northeastern United States (US). The paper presents case histories of the performance of displacement piles in the Northeastern US including the use of full displacement elements as a settlement limiting ground improvement system.INTRODUCTION“Drilled Displacement” (DD) is an industry umbrella term for a number of proprietary or commercially available cast-in-place pile installation systems which involve a hollow-stem tool that laterally displaces soil as it advances and the placement of grout or concrete through the hollow-stem tool as it is withdrawn. The systems include grout/concrete placement methods by both sand-cement grout pumped under pressure and tremie grout/concrete placement through bottom-hole discharge. The system discussed in this paper includes grout pumped under pressure, also referred to as Auger Pressure Grouted Displacement (APGD). A schematic of the APGD tool is shown in Figure 1. The tools require significant torque and downward force to advance; a typical installation platform is shown in Figure 2."

Jan 1, 2016

By Emre Turk, Suat Gullu, Candan Gokceoglu, Ahmet Sirri, Asli Can

In this study, the ground improvement application applied under the live railway bridge's approach embankments in Sivas, Türkiye was investigated as a case study. The soil profile is mainly composed of orangish conglomerate, clay, silty sandy clay, and under claystone, and mudstone units in the study area. As a soil improvement method, the Deep Soil Mixing (DSM) technique based on the principle of simultaneous mixing the ground while injecting with the water-cement mix, was selected. The application of DSM columns is designed to be 45 degrees horizontal, in order to reach the deepest point of the soft clay units for better improvement against settlement. The core samples were taken from the DSM columns and the compressive strength tests were performed in the laboratory. The results were higher than the minimum designed values. It means that inclined DSM columns were applied successfully, and the excessive settlement problem was solved.

Oct 1, 2022

By Julie H. N. Hampden, Per G. Reinhall

"Executive summary: Impact pile driving of steel piles is a common construction practice in freshwater and marine environments for the building of structures and foundations. This practice produces extremely high sound levels underwater that have proven injurious to aquatic fish and wildlife. To limit impacts to sensitive species, resource management agencies employ a variety of different strategies including timing restrictions to limit in-water construction windows to those months when there are low flow conditions in lakes or rivers, to those hours when tides are low, or to periods of the year when species of concern are least likely to be present in the project vicinity. In addition, permitting agencies have identified noise thresholds above which sensitive species could be injured, resulting in additional project conditions to curtail the extent of project noise impacts including: limiting the number of piles or pile strikes per day, requiring biological monitoring, and mandating the use of noise attenuation techniques, such as bubble curtains and cofferdams. Numerous studies have shown current noise attenuation techniques are costly and provide limited or variable noise reduction [1-3]. This is because the noise from pile driving is not only transmitted through the water column, it is also transmitted through the sediment back into the water column [1, 4-8]. Though these protective measures may help to reduce project impacts, they also result in additional complexity, expense, and potential risk for project delivery. Marine Construction Technologies, a Public Benefit Corporation, in collaboration with University of Washington and Washington State Department of Transportation, has developed a pile that can be installed with standard pile driving technologies (vibratory or impact hammers) and consistently decreases the total noise transmitted into the water. The double-walled pile is relatively quiet in comparison to unattenuated piles or existing noise attenuation techniques. This technology not only reduces the risk to sensitive species by minimizing the extent of potential impacts, it also reduces potential risks to project delivery by limiting the size of monitoring areas, minimizing the need to cap daily production rates, and eliminating the need for deployment of additional noise attenuation devices. Results from finite element modeling of the pile, scaled prototype testing, and full scale field testing in Commencement Bay (October 2014) and Vashon Island (October 2015) in Puget Sound, Washington indicate a reduction the peak sound pressure between 14 and 20 dB relative to single walled piles at a range of approximately 10 meters. These tests also confirm that the double-walled piles provide drivability similar to standard steel piles. In addition, preliminary calculations for capacity and structural characteristics demonstrate that double-walled piles provide equivalent or better performance than same-sized standard piles."

Jan 1, 2017

By Faisal Shalzad, Adnan Anwar Malik, Tadashi Maejima, Jiro Kuwano

Single helix screw piles carry most of the structural load through end-bearing if the helix is embedded in the dense bearing layer. The tip condition of the central shaft of the screw pile can be closed, closed with cutting blades, opened with flat cut, and opened with wedge shape cut and its selection is based on the insitu ground conditions. These different end conditions of the central shaft disturb the ground differently, leading to the change in bearing capacity. In this study, an attempt is made to investigate the effect of open and close-end screw piles on installation effort (installation load and torque) and bearing performance in the dense bearing layer. The model steel screw pile with a pile shaft diameter of 21.7 mm and helix diameter of 43 mm is used in this study. Test results show that the open-end screw pile required less installation effort than the close-end pile that penetrated the bearing layer by 1Dhwith an unplugged condition. Further, the open-end screw pile shows a higher bearing response than the close-end screw pile if it enters the bearing layer with an unplugged condition.

Oct 1, 2022

By Jr NeSmith

"Augered-cast-in-place (ACIP) pile installation technology has matured extensively since the first auger, pressure grouted pile was patented in 1959. The current technology allows for successful pile installation across a variety of stratigraphies to meet various project load resistance requirements. This paper presents an overview of current ACIP techniques by comparing a number of case histories in a variety of geologic settings from Eastern Pennsylvania, New York City and New Jersey to demonstrate ACIP pile constructability in soft soils as well as the penetration, and resulting significant loads resisted, of ACIP piles in dense soils and intermediate geo-materials. Geologic settings that will be discussed include the Piedmont and Coastal Plain geologic provinces as well as glacial till deposits. Keywords: Deep Foundations, Piles, Augercast, Augered-cast-in-place, Auger pressure grouted, ACIP, APGINTRODUCTIONThe author, along with two colleagues, published an article in Deep Foundations magazine (NeSmith et al, 2013) which described a number of the advances in equipment, techniques, installation monitoring and post-construction testing that have expanded the geologies in which Augered Cast-in-place (ACIP) piles are installed as well as increasing their efficiency in some traditional ACIP pile geologies. The author uses the term efficiency to refer to the load resisted by a pile of a certain diameter and the increased efficiency noted refers to increased allowable loads over those traditionally resisted by piles of certain diameter (or a reduction in pile diameter from that which was traditionally used to support a certain design load). The performance and installation of ACIP piles in a variety of geologies in the Northeastern U.S. are discussed herein.PIEDMONT PHYSIGRAPHIC PROVINCEThe Piedmont physiographic province stretches from Alabama to the east through Georgia and up the east coast, just west of the Coastal Plain to Pennsylvania and New York (Brown, 2002). It generally consists of soils weathered in place from the underlying bedrock, which is typically a combination of granite, schist and gneiss depending on the location within the province. The author’s experience in the Northeastern US has been on sites where alluvial or coastal plain soils overly the residual soils and partially weathered or intact rock of the Piedmont. The example presented here, from a site on Walnut St in Philadelphia PA, is representative of these projects."

Jan 1, 2016

By Ramanathan Ayothiraman, Anurag Singh

"An experimental program was undertaken to investigate the effects of randomly distributed basalt fibre on the index and engineering properties of Dhanori clay and to compare its performance with the properties of soil reinforced with polypropylene fibre. In the present investigation, 7 groups of soil samples were prepared at four different percentages of basalt fibre and polypropylene fibre content and tests were done for measuring their consistency limits, compaction characteristics, unconfined compression strength and consolidation properties. The test results indicate that the inclusion of basalt fibre in Dhanori clay resulted in significant improvement in properties. The improved properties are not comparable with polypropylene fibres, nevertheless, the improvement by basalt fibres is able to meet the typical design target values and the cost is very much less than synthetic fibres. More importantly, basalt fibres are environment friendly.INTRODUCTIONConstruction of buildings in low lands with engineered filling, flexible and rigid pavements for highways/airfields, and embankments for highways/railways are also part of major infrastructural development in addition to construction of tall buildings, bridges/fly overs, major dams and underground structures. The later projects require different improvement techniques than that is adopted in the former projects. Ground improvement techniques such as use of reinforcement inclusions within soil found as an effective and reliable technique. Especially such modification by fibre reinforcement, is primarily possible in engineered filling, pavements subgrade and embankments, where surface mixing is easier; and may not be feasible when stabilization/modification is required for deeper depths. In comparison with conventional reinforcement using geosynthetics (strips, geotextile, geogrid, etc.), there are some advantages in using randomly distributed fibre as reinforcement. In past few decades, the discrete fibres are simply added and mixed randomly with soil, in much the same way as cement, lime, or other additives.There are several studies (Ziegler et al. 1998; Puppala et al. 2000; Bei-xing et al. 2004; Cai et al. 2006; Tang et al. 2007, 2012, 2016; Abdi et al. 2008; Viswanadham et al. 2009; Le et al. 2015) that investigated the behaviour of polypropylene fibre-reinforced soil and reported that an increase in fibre content caused an increase in strength and shrinkage potential but brought on the reduction of swelling potential. The length of fibres had an insignificant effect on soil characteristics, whereas fibre contents proved more influential and effective. A study on rubber fibre conducted by Hambirao and Rakaraddi (2014) mentions that tensile cracking of clays can be improved with the inclusion of short rubber fibres, optimum fibre content was about 15 % of weight of soil. Several experimental studies (Babu et al. 2008; Chaple and Dhatrak 2013; Vibhakar and Nahta 2014; Soundara and Senthilkumar 2015; Goyal et al. 2015; Jayasree et al. 2014, 2015) were conducted on coir fibre-reinforced soil and concluded that it helped in reducing the swell potential and 1% fibre by weight of the soil almost doubled the CBR value. Martins et al. (2015) found that 4% of sisal fibre by weight of the soil reduced the visibility of cracks. Pillai and Ayothiraman (2012), Ayothiraman et al. (2014) and Sahu et al. (2016) have demonstrated that human hair fibres can be used to improve the properties of both fine grained and coarse grained soils."

Jan 1, 1900

By Takeshi Maki, Kh. Adeel Tariq

"The lateral resistance of the structure plays an important role during seismic event and it can be increased by using ground improvement. In this study an attempt has been made to investigate the effect of cement-treated sand on the lateral capacity of the pile. The behavior of piles surrounded by sand only and cement-treated sand confined in a steel box (30 x 30 x 50 cm) which is subjected to lateral cyclic load has been investigated. Piles having a diameter of 2.5 cm and embedded to a depth of 45 cm were used. Steel and aluminum piles were used to investigate the effect of flexural stiffness on the lateral capacity of the pile. Bottom supports of piles were also changed from pinned to fix. Well graded sand compacted to 70% of relative density (RD) was used. Cement-treated sand having a compressive strength of 3.7 MPa was used. Displacement controled lateral load tests were performed and cyclic loads were applied until pile displacement was 4%, 10%, 20%, 35%, 50%, 75% and 100% of pile diameter. Results evaluated are compared with common method of analysis like Brinch hansen (1961), Brom (1964), Poluos (1980) etc. Results have indicated that the stiffness of a pile affects its lateral capacity. The introduction of central cement-treated sand part increased 5 times the lateral capacity of piles as compared with a sand only condition.IntroductionPiles are used extensively around the world to support loads of structures. Piles are commonly used to carry axial load, but in some structures, the lateral capacity of the pile is more important than the axial capacity: for example piles supporting earth retaining structures, electric tower foundation, etc. Structures can be subjected to both axial and lateral forces, like structures constructed at harbor that are subjected to lateral force due to waves action; and structures built in earthquake prone areas like Japan."

Jan 1, 2017

By Bernardo J. Jiménez Vega, Edy L. T. Montalvan

Rammed stone columns and similar reinforcement systems are used worldwide more frequently as a cost-effective method for improvement of foundations on soft soils. The effectiveness of the treatment method is evidenced by the increase in bearing capacity and reduction of compressibility of the treated ground. In this study, two job sites with over 500 stone columns were studied. On both jobs sites, shallow soft silty soils were found and stone columns were designed to support the foundations of MSE walls, which serve as abutments for viaducts. In order to verify the soil improvement efficiency CPT tests were performed before and after the construction of stone columns, also plate load tests were performed on both job sites to verify the deformation modulus of the stone columns. From CPT data it was observed an increase up to 30% of sleeve friction and 20% of tip resistance, which demonstrated a higher deformation modulus maintaining the same strength in the soil after stone columns construction. The plate load tests yield load-deformation curves which indicated that the original assumed modulus was conservative. As a result of these findings, optimization of the settlement reduction ratios was conducted using the modified values of deformation modulus for the soil and stone column, obtaining a reduction up to 30% of stone columns for further job sites with similar soil conditions.

Sep 8, 2021

By Gerald Verbeek, Erick Baziw

"Downhole Seismic Testing (DST) is an important geotechnical testing technique for site characterization as it provides low strain (<10-5) in-situ interval compression (Vp) and shear (Vs) wave velocity estimates. These velocities are determined by obtaining relative arrival times of source waves as they travel through the stratigraphy and are recorded by one or more vertically offset seismic sensors. A challenging aspect of this process is to characterize the seismic data sets to determine the analysis method that will result in the most accurate interval velocity values. This paper introduces an assessment technique which utilizes linearity estimates (i.e., hodograms fitting straight lines) from the polarization analysis in conjunction with crosscorrelation coefficient calculations of the full waveforms as well as the deviation of the source wave frequency spectrum from a desirable bell-shaped curve. The paper will provide an overview of the technique and include some examples of actual data sets where the technique was applied to analyze those data sets.1. INTRODUCTIONIn general terms, Downhole Seismic Testing (DST) such as Seismic Cone Penetration Testing (SCPT) is a geotechnical technique for measuring in-situ shear and compression wave velocities (VS and VP respectively). The main goal in DST is to obtain arrival times as the source wave travels through the soil profile of interest, and from these arrival times the velocities are then calculated. Figure 1 shows a schematic of the typical DST configuration: a seismic source is used to generate a seismic wave train at the ground surface. One or more downhole seismic receivers are used to record the seismic wave train at predefined depth increments. The downhole receiver(s) may be positioned at selected test depths in a borehole or advanced as part of an instrumentation package as in the case of SCPT. When triggered by the seismic source a data recording system records the response of the downhole receiver(s)."

Jan 1, 2017

By Sameh M. Khella

This paper discusses the application of deep CFA piles for the foundation of structures in different ground stratifications with a focus on the application in Queensland region. Design, construction techniques and quality measures implemented during these procedures are described. Testing methods and verification of capacity, integrity and performance of these piles are also demonstrated. Case studies for this application are presented with an appreciation of this solution within the provided project conditions of each case. Examples of successes and challenges encountered over the course of application of deep CFA in Queensland are mentioned. Limitations of the technique and less favourable situations for its implementation are also highlighted.

Nov 1, 2022

By Ignatius P. O. Lam

This paper presents information on design analyses of large diameter piles using conventional p-y curves as recommended by the American Petroleum Institute (API RP2A, 1993). API RP2A adopted the soft clay criterion developed by Matlock (Matlock, 1970) based on 12.75-inch piles. API RP2A also adopted the API sand criteria originally introduced by Reese, Cox, and Koop (Reese et. al., 1974) based on 24-inch piles. Since Matlock and Reese published their original papers, there have been several publications recommending changes to their p-y criteria, especially regarding the need to adjust the Matlock p-y curves for pile diameter effects. The following sections attempt to clarify the issue of diameter effects on p-y curves.

Jan 1, 2013

By Ruth McKeown, Gilson de F. N. Gitirana, Murray Fredlund, HaiHua Lu

The current design standards for the use of anchors in slopes is based on two-dimensional (2D) limit equilibrium analyses. Anchors are considered as discrete loads and the 2D anchor, factored based on the spacing distance, corresponds to extending anchors indefinitely in the third dimension. A three-dimensional (3D) analysis offers a more realistic representation of the problem, including the true discrete nature of the anchor point loads. This paper explores the typical differences between analyzing anchors in 2D and 3D, using four typical conceptual models. Slopes with constant cross sections were shown to be adequately represented by the traditional 2D approach. The maximum difference between 2D and 3D models was 21% and becomes negligible for lower anchor spacing values, as expected. A slope with an external load was analyzed to evaluate critical slip surfaces with lower aspect ratios. Slip surfaces with lower aspect ratios presented higher edge effects that contributed to the stability of the slope. The results indicate that optimum design requires the 3D evaluation of field conditions inducing low aspect ratios, such as concave and convex surfaces, weak layers, and external loads. INTRODUCTION Slopes may be stabilized using a variety of solutions, including anchors. When performing an analysis, geotechnical engineers often follow the traditional two-dimensional (2D), Limit Equilibrium Method (LEM). It is important to understand the consequences and limitations of the assumptions on which the 2D LEM is based. There are numerous studies on anchors that show the importance of considering the actual three-dimensional field conditions. Desai et al. (1986) proposed a three-dimensional procedure based on the Finite Element Method and considering elastoplastic behavior and interface elements, to account for stress and displacement distributions, the relative motion between the anchors and the soil mass, and nonlinear soil behavior. Several important stabilization mechanisms were explained. The role of grout injection was evaluated in terms of the produced normal stresses along the anchor-soil bounding surface. The approach was shown to reproduce adequately experimental tests on a sand, proving realistic stress distributions around the anchor. Nonlinear soil behavior influenced to a large extend relative interface motions. Michalowski (1989) applied an upper-bound limit analysis in 3D to slope stability analyses. Anchors were not specifically considered in this study, but the consideration of locally loaded conditions shed light on important modeling aspects. The manner how the slide mechanism becomes three- dimensional as the slope is locally loaded was demonstrated. This emphasizes the fact that anchors should produce field conditions that require 3D analysis approaches.

Jan 1, 2019

By Peter J. Jancich

This paper describes the installation of high capacity Augered Pressure Grouted piles which support structural loading from a four level parking garage in west-central DuPage County, Illinois. The subject site is characterized by a variable glacial geology which presented, to the designer, a number of problems with respect to analysis and prediction of pile capacities, and, to the contractor, the very real difficulties associated with estimating the costs of, and installing foundation units in highly variable subsurface conditions. 2. General Site and Subsurface Conditions 2.1 Site Conditions - The subject site is part of an overall 300 acre property. Topographically, the overall site is saddle shaped with higher elevations along north and south boundaries and a subdued, east-west trending swale centrally located. Elevation relief is on the order of 25-30 feet (7.6-9.2m).

Jan 1, 1991

By K. Rainer Massarsch

"Part 2 of 2 (Continued from Summer 2004 edition) By K. Rainer Massarsch, Geo Engineering AB, Stockholm, SwedenVibrations, which are caused by the installation of piles in dry or permeable soils, can cause settlements. The magnitude of settlements depends on several factors, such as soil type and stratification, ground water conditions (degree of saturation), pile type and method of pile installation (driving energy). A method of settlement prediction due to construction-induced vibrations has been presented by Massarsch (2000). However, in many cases, an engineering assessment must be made at an early stage of a project. The following simplified procedure can be used to estimate settlements in a homogeneous sand deposit adjacent to a single pile, Fig. 5. This approach is based on extensive experience from soil compaction projects. It is assumed that intense densification due to pile penetration occurs within a zone corresponding to three pile diameters. The volume reduction resulting from the propagating vibrations will cause settlements in a cone with an inclination 2V:1H, with the tip at a depth of 6 pile diameters. Thus the settlement trough will extend a distance of 3D+L/2 from the centre of the pile, with maximum settlements at the centre of the pile. Maximum settlements, Smaxand average settlements, Smax can be estimated using the following relationship, choosing an appropriate a value of the soil compression factor, from Table 2.The driving energy depends on the method of pile installation, soil stratification and the pile type. The displacement volume of the installed pile has been neglected. The simplified method is applicable for estimating settlements at the perimeter of a pile group. It should be noted that settlements also occur outside the assumed cone, but these are often negligible. The effect of incompressible layers should be taken into account by adjusting the effective pile length."

Jan 1, 2004

By Michael W. Oakland

Weidlinger Associates was retained to evaluate the foundations supporting ten oil storage tanks at a tank farm on the east coast. The tanks were constructed over the site of a landfill which was underlain by deep organic deposits. The tanks were typically 48 ft. in height and ranged in diameter from 60 to 150 ft. The tanks were supported on both wood and steel pipe piles. After more than 35 years of service, an inspection found that up to 25 percent of the piles had separated from the mat foundation. The operations at the facility were temporarily stopped pending further investigation. Weidlinger developed comprehensive finite element models of the foundations for each tank and used random generators to conduct Monte Carlo simulations the range of scenarios of detached support conditions since it was not possible to survey all the piles below the tanks. To confirm the modeled performance and verify stability, each tank was also load tested using water with electronic instrumentation installed by Geo-Instruments. The instrumentation provided real time, web based monitoring during testing in areas which would otherwise be inaccessible during loading. Through inspection, complex modeling and sophisticated load testing, Weidlinger and Geo-Instruments were able to show that all but one of the tanks could safely be put back into service. This paper details the analysis, Monte Carlo simulations and instrumentation and load testing performed for this unique project.

Jan 1, 2009

By Fred Tarquinio, Giovanni Bonita, Lars Wagner

"A new embassy for the Peoples Republic of China is under construction in Washington, DC. The 475,000 square feet (44,125 m2) structure has five levels below ground and four above, making it the largest embassy in Washington DC. A vertical soil nail wall was used as the primary support of excavation system for the project. The soil nail wall was irregularly shaped, benched in areas, and up to 98 feet (29.9 m) in height. The soil nail and shotcrete system consisted of approximately 1,600 soil nails and 50,000 square feet (4,645 m2) of exposed shotcrete wall surface. Design and construction challenges included soft soil conditions, inside wall corners, underground utilities, seismic impacts from blasting, and logistical and political factors. Overall, wall movements were lower than expected, with maximum horizontal movement less than 0.25% of the total height of the excavation. INTRODUCTIONThe proposed Embassy of the Peoples Republic of China in Washington, DC, will consist of about 475,000 ft2 (44,125 m2) of building space and contain up to four fl oor levels above ground and fi ve levels of basement (Figure 1). When completed, the building will be the largest embassy in Washington, DC. The architect for the project, Pei Partnership Architects, along with the world-renowned architect I.M. Pei, made effi cient use of the site by inserting the building into the existing slope. Consequently, excavations reach heights up to 98 feet (29.9 m) on the southern side of the property and 42 feet (12.8 m) on the northern side.The soil nail and shotcrete system consisted of approximately 1,600 soil nails and 50,000 square feet (4,645 m2) of exposed shotcrete wall surface. The location of the building relative to the property line called for tight excavation requirements, including precise wall positions and shotcrete tolerances. Design and construction challenges included soft soil conditions, inside wall corners, arched walls, underground utilities, seismic impacts from blasting, and logistical and political factors."

Jan 1, 2007