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Tunnels are constructed increasingly close to existing buried structures, including pile foundations. This poses serious concerns, especially for tunnels built beneath piles. Current understanding of the global tunnel--soil--pile--building interaction effects is lacking, which leads to designs that may be overly conservative or the adoption of expensive measures to protect buildings. This paper presents outcomes from 24 geotechnical centrifuge tests that aim to investigate the salient mechanisms that govern piled building response to tunneling. Centrifuge test data include greenfield tunneling, pile loading, and tunneling beneath single piles and piled frames, all within sand. The global tunnel-piled frame interaction scenario is investigated using a newly developed real-time hybrid testing technique, wherein a numerical model is used to simulate a building frame, a physical (centrifuge) model is used to replicate the tunnel-soil-foundation system and structural loads, and coupling of data between the numerical and physical models is achieved using a real-time load-control interface. The technique enables, for the first time, the modeling of a realistic redistribution of pile loads (based on the superstructure characteristics) in the centrifuge. The unique dataset is used to quantify the effects of several factors that have not previously been well defined, including pile installation method, initial pile safety factor, and superstructure characteristics. In particular, the results illustrate that pile settlement and failure mechanisms are highly dependent on the pretunneling loads and the load redistribution that occurs between piles during tunnel volume loss, which are related to structure weight and stiffness. The paper also provides insight as to how pile capacity should be dealt with in a tunnel-pile interaction context. [ABSTRACT FROM AUTHOR]

The exertion of super-long pile skin friction is an asynchronous process in deep soft soil area. The limitation of skin friction on the upper part of pile is much smaller than the lower part of pile. The softening of super-long pile skin friction is also a common phenomenon. Therefore, a new hyperbolic load transfer model is proposed in this paper, which takes into account the softening of pile skin friction and the nonlinear characteristic of pile-soil relative displacement. Meanwhile, a User-Defined Material (UMAT) subroutine is written in FORTRAN language and connected with an ABAQUS interface. The curve of pile skin friction is obtained, which is more consistent with practical engineering. It is further developed into a universally applicable function of super-long piles. The settlement and effective pile length in deep soft soil area can be calculated by a new function with the consideration of super-long pile weight. Example analysis shows that the calculation of axial force distribution of super-long pile, settlement of pile top, and effective pile length are more consistent with pile test results. In summary, the method proposed in this paper can exactly reflect the working characters of super-long pile in practical engineering, which can provide valuable reference for the design of super-long pile. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Low-strain testing of piles is routinely performed by striking the pile head with a small hand-held hammer, usually aiming for the pile centre, and measuring the vertical velocity response by means of a receiver placed also on the pile head. In practice, however, it is impossible for the operator to perfectly align the point of impact with the pile centre, as existing solutions for the interpretation of the velocity measurements assume. In the general case where the impact load is eccentric, the wave field is no longer axisymmetric with respect to the pile axis and waves resulting from the hammer impact can propagate along the vertical, radial and circumferential directions. This is taken into consideration in the analytical solution presented in this note, which provides the non-axisymmetric dynamic response of a pile to an impact load applied at an arbitrary position on the pile head. Arithmetic examples are used to depict the three-dimensional non-axisymmetric vibration characteristics of the soil-pile system, with emphasis on the effect of the eccentricity of the impact load on the optimal position of the receiver, the identification of which is essential for obtaining meaningful results from low-strain integrity tests. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Very often the numerical simulations are based on full scale instrumented and small scale model pile tests. Most of the parameters necessary for modeling of full scale piles is usually derived from in situ tests profiles. This common practice generates a significant amount of uncertainties. Therefore, another pile testing technique - centrifuge test is often used as alternative. Despite its acknowledgment and wide usage, it has some shortcomings, such as scale effects. This paper presents the original experimental and numerical study, performed in comprehensively explored artificial sand deposit, using large scale model pile test and FEM analysis. For the numerical simulation the Hardening soil model was used in order to reproduce highly nonlinear predominant performance of pile base. After the FEM analysis, it was concluded, that shaft capacity mainly depends on the radial stress which were induced in the adjacent soil during installation process. It was also reported, that base capacity strongly depends on pre – consolidation stress, and was highlighted the most important parameter which influences the base load – settlement performance when HS model is used. [ABSTRACT FROM AUTHOR]

Results of static pile tests using the static cycling quick-load test (SCQLT) and Osterberg (O-Cell) methods are presented. [ABSTRACT FROM AUTHOR]

A semi-analytical method for calculating the response of single piles and pile groups subjected to lateral loading is developed in this paper. Displacements anywhere in the soil domain are tied to the displacements of the piles through decay functions. The principle of virtual work and the calculus of variations are used to derive the governing differential equations that describe the response of the piles and soil. The eigenvalue method and the finite difference technique are used to solve the system of coupled differential equations for the piles and soil, respectively. The proposed method takes into account the soil surface displacement along and perpendicular to the loading direction and produces displacement fields that are very close to those produced by the finite element method but at lower computational effort. Compared with the previous method that considered only the soil displacement along the loading direction, accounting for the multi-directional soil displacement field produces responses for the piles and soil that are closer to those approximated by the finite element method. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper advocates the use of a multiphase model, already developed for static or quasi-static geotechnical engineering problems, for simulating the behaviour of piled raft foundations subject to horizontal as well as rocking dynamic solicitations. It is shown that such a model, implemented in a FEM code, yields appropriate predictions for the foundation impedance characteristics, provided that shear and bending effects in the piles are taken into account, thus corroborating the findings of the asymptotic homogenization theory. Besides, it is notably pointed out that such a multiphase-based computational tool makes it possible to assess the dynamic behaviour of pile groups in a much quicker way than when using direct numerical simulations, which may face oversized problems when large pile groups are concerned. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper presents theoretical analysis of the parallel seismic (PS) method for evaluating existing piles using the flexural mode wave exited by a horizontal impact on the lateral surface of a pile. A simplified theoretical model of the flexural wave for PS method was established to elaborate the theoretical basis. A correction factor was then obtained and proposed to correct the pile depth obtained from the PS method, thus providing a more accurate estimation. A three dimension (3-D) finite element (FE) model was developed and the existence of the flexural waves on branch F(1, 1) in the pile shaft has been verified. Two time domain methods were used to calculate the flexural wave velocity in the pile. One was based on the pile tip reflection signal using a model where pile head reflection was minimized, and another method used the slope of the upper fitted line in the PS test. The flexural wave velocities from both methods match well with the predicted flexural wave group velocity determined from the dispersion curve of a 1-D rod embedded in the soil. The accuracy in estimation of pile tip depth is improved by applying the correction factor. A series of parametric studies were carried out to demonstrate the effectiveness of using flexural wave for PS test and the correction factor proposed in this study. [ABSTRACT FROM AUTHOR]

Axially loaded piles installed in layered soils where the upper soil layer is still consolidating are subjected to the combined interactive action of axial load and drag load. The shift of the location of the neutral plane as a result of the interaction of the axial load and drag load leads to the possibility that such piles need not account for the negative skin friction in determining the maximum pile force for the pile structural design. The results of a series of centrifuge tests on axially loaded piles in consolidating layered soil are presented so that the effect of negative skin friction on pile settlements and locations of the neutral plane of such piles can be better understood. The criteria regarding whether negative skin friction needs to be accounted for in determining the maximum pile force for the pile structural design are established in the present study based on centrifuge test results and findings reported in the literature. [ABSTRACT FROM AUTHOR]

A series of laterally loaded pile tests carried out both in natural ground and in cemented treated soil is presented in this paper. The length to diameter ratio L/D of the piles was selected as 5, representing the behavior of a free-headed, short pile that will move as a rigid body in the direction of the applied load without structural damage. The extent of the treated soil layer around the pile ranged from 2-4 times the pile diameter and 0.1-0.3 times the pile length. The treated layer was a mixture of Osorio sand and early strength portland cement. Experimental results show a significant increase in lateral load resistance of short piles when the soil is treated with cement. [ABSTRACT FROM AUTHOR]

The authors respond to the discussion made in their study "Instrumented Static Load Test on Rock-Socketed Micropile." Topics covered include one discusser's focus on the estimation of the load and displacement at the pile base from load test measurements and the elastic modulus of the test pile, and ways in which geotechnical failure could be estimated from the test data according to another discusser.

The article discusses the quality control and review process conducted by engineering firm Aurecon Group Brand Pte Ltd.'s Ground Engineering division on the piling installation works at the Futila Sea Breeze development in Cabinda, Angola. A background of the project is provided which features staff residential buildings and related facilities for foreign petroleum firms. Also discussed are the site's ground conditions, full-scale static load testing, and test pile results analysis.

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the three-dimensional characteristics of wave propagation in platform-pile system, a three-dimensional computation model for transient vibration of platform-pile-soil system is established. Based on initial and boundary conditions, the numerical solution of this model is obtained. A MATLAB program is compiled through using staggered grid finite difference method. The dynamic response of the integrate pile in platform-pile-soil system is got under vertical impact force, and the reliability and feasibility of the numerical simulation are corroborated by comparing calculation result with measured data of low strain integrity testing of platform-pile system. The optimal sensor location at platform top is studied. The results show the position distancing the pile center 0.5 R ~0.6 R ( R is pile radius) is the optimal sensor location, which the line between sensor location and pile center parallels the short side. It plays a certain role in reducing three-dimensional interference through increasing shear wave velocity of surrounding soil and appropriately increasing the ratio of characteristic wavelength to pile radius. In addition, contact area has less influence on low strain integrity testing of platform-pile system. [ABSTRACT FROM AUTHOR]

This paper tabulates the results of 175 static load tests carried out in Ireland, and includes bored, continuous flight auger and driven piles in fine- and coarse-grained material, and also piles terminating in rock. These data are used to show that the ultimate pile resistance (defined at 0·1 times the effective pile diameter, ) predicted using Chin's extrapolation method was within the range 85-100% of the measured resistance when the pile head settlement was greater than 0·05. The coefficient of variation of the compressive resistance of the ground against a pile, , for a varying number of load tests carried out on a site reduced from 40% where a single test was carried out to 20% where eight tests occurred. This is considered to be a reasonable lower bound to the within-site variation in , and it is recommended that this level of variation be considered for pile design. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An extensive program of centrifuge testing was conducted to quantify the improvements to seismic slope performance that can be achieved by installing a row of discretely spaced vertical precast RC piles. A key novelty of the work presented is the use of recently developed microreinforced concrete to produce realistically damageable model piles. Pile-reinforced slopes are a good example of a problem in which relative soil-pile strength is important in determining whether the soil or pile yields first, and in which the performance of a slope with structurally damaged piles may be of interest. The new model RC allows these factors to be properly accounted for in a reduced-scale physical model for the first time. Two different reinforcement layouts were considered, representing (1) a section specifically detailed to carry the bending moments induced by the slipping soil mass, and (2) a nominally reinforced section with low moment capacity. These were supported by further tests on conventional elastic piles that were instrumented to measure seismic soil-pile interaction. It was demonstrated that dynamic ground motions at the crest can be significantly reduced in amplitude by up to 20% with elastic piles spaced at s/B=3:5, both in terms of the peak acceleration and across the full response spectrum. Permanent deformations at the slope crest (e.g., settlement) were also reduced by up to 35% at s/B=3:5. These findings are consistent with previous suggestions made for the optimal s/B ratio for encouraging soil arching between piles at maximum spacing both under monotonic conditions and from numerical investigations of the seismic problem. The improvements to slope performance were reduced slightly using the designed microreinforced concrete piles owing to deterioration in the bending properties arising from fatigue under the cyclic kinematic loading. This suggests that idealization of RC piles as elastic elements will likely be only an approximation of their true behavior. The importance of reinforcement detailing was also highlighted, with the nominally reinforced section yielding early in the earthquake, and the damaged piles subsequently only offering a small (although measureable) reduction in seismic slope performance compared with the unreinforced case. In addition to these findings, the data presented will be useful in validating future improved numerical models for predicting the performance of piled slopes and for the aseismic design of pile-reinforcing schemes. [ABSTRACT FROM AUTHOR]

Torsional load on pile foundations is induced by the action of eccentric horizontal forces on the supporting structures. Such loading not only initiates twist at the pile head, but also reduces its axial capacity significantly associated with increased settlement of the foundation. Inadequate design of piles under torsion may lead to disastrous consequences. Although several theoretical and experimental investigations have already been carried out on piles under torsional load as evidenced from the available literature, there is ample scope for further contributions on the influence of torsional load on pile foundation. This paper presents a novel numerical model (boundary element method) to analyze the response of a single, vertical, floating pile subjected to pure torsional load. The nonlinear stress-strain response of soil has been incorporated in the model by hyperbolic correlation, whereas the pile material has been idealized as elastic-perfectly plastic. The effect of progressive pile-soil slippage at the interface is considered. Apart from predicting the load-displacement response with incremental angle of twist of pile under pure torsion, the profiles for shear stress and angle of twist and the depth of interface slippage are some of the salient features captured by the proposed model. Validation of the model developed by comparing with existing models and experimental data indicate the suitability and accuracy of the solutions developed. However, minor discrepancies in the solution appeared owing to the simplified assumptions of perfectly plastic postpeak soil behavior and the absence of residual stress in the soil owing to pile installation. The proposed model is also applied successfully to selected case studies on concrete piles ( L/D ranged from 10-40) in medium-soft clay, medium-dense sand, and layered soil, and a set of design curves have been constructed. [ABSTRACT FROM AUTHOR]

This paper presents the results of a field test performed to study the effects of installation method on the load–displacement response of piles used to support the offshore wind turbines. An instrumented open-ended model pile was installed by jacking in a deposit of medium-dense sand. Pile jacking has environmental benefits over the traditional method of pile driving which can cause noise and vibration damage to the marine mammals. Pile installation by jacking was shown to enhance the pile-soil stiffness response during compression loading. Residual stresses, generated during the installation process, caused the pile to exhibit a relatively soft stiffness response during tension loading. Environmental loading caused by wind and waves which causes piles that support jacket structure to experience tension loading and the serviceability limit state of the foundation to these loads governs the design. [ABSTRACT FROM PUBLISHER]

Abstract: The parallel seismic (PS) method is used for determination of the unknown or undocumented depth of foundations, mostly piles. It was developed several decades ago and has not much changed since. PS is based on impulse generation on the pile head and registration of travel times in a borehole parallel to the foundation. The method is applicable to many foundation types, including single piles, pile walls, or sheet piles. While the accuracy is known to be high if the distance between foundation and borehole is small, the foundation length is overestimated with increasing distance. This paper presents the results of a systematic study on the influence of geometric and material parameters on the measurement results and explains the effects by studying the underlying wave phenomena based on numerical studies. It can be shown that several parameters (e.g. borehole inclination) have a strong influence. Foundation flaws and soil layers have also to be taken into account, while the possibilities in the other direction (derivation of soil parameters or detection of flaws from the results) are limited. Based on the simulation results, a new mathematical algorithm for data interpretation has been developed which takes into account the soil layers and the borehole inclination. This novel data interpretation scheme was used in combination with different data inversion methods. The new interpretation method was successfully validated using several sets of simulated data. Not only was it shown to be more accurate than all other available methods, but it also extended the maximum allowable pile–borehole distance to 2–3m. Today, parallel seismics is the only method applicable on both metallic and non-metallic foundations which can be used without calibration. It has the largest range of all borehole methods. To enhance its efficiency it can be combined with downhole seismic measurements in the very same borehole to retrieve soil parameters. [Copyright &y& Elsevier]

Abstract: A new runway (named ‘D-runway’) for Tokyo Haneda International Airport was constructed offshore in Tokyo Bay to accommodate the recent increase in overseas and domestic flights to and from Tokyo. One of the most outstanding characteristics of the new runway is that it stands on two types of different structures: steel-jacket-platforms forming a pier-type structure and a reclaimed soil structure. The pier-type structure minimizes disturbance of water flow at the nearby Tama river mouth due to the presence of the new runway. This paper relates to the design and construction of the steel-jacket platforms for the pier structure. The main focus is on the results of pile load tests carried out to confirm the pile design, and the actual construction of the jacket structures. Through the construction of this pier-type structure, it has been possible to confirm the applicability of rapid load tests for large-diameter long steel pipe piles, the validity of the assumed pile tip plugging ratio used for design, and the applicability of a simple method for controlling the end of pile driving. Further, the effectiveness of joint-less work piles, the pile-keeper system, and GPS monitoring in the rapid and accurate construction of pier-type jacket structures was demonstrated. [Copyright &y& Elsevier]

Abstract: The effects of existing piles on the vertical bearing capacity of piles of a new building were examined using vertical static loading centrifuge tests on a new pile located among existing piles. The results suggest the following conclusions: (1) Existing piles increased the total shaft resistance of the new pile with a rough surface because the existing piles restrained the soil around the new pile and the positive dilatancy of the sand increased the confining pressure of the soil. (2) The shaft resistance of the lower part of the new pile with a rough surface fell rapidly during the loading tests, regardless of whether there were existing piles or not. The diminution of shaft resistance, known as ‘friction fatigue’, was probably caused by sand particle crushing in the vicinity of the pile end. (3) For a new pile with a rough surface, existing piles did not affect the end resistance when the new pile head settlement normalized by the pile diameter, s/D p, was less than 0.2. (4) Existing piles did not affect the shaft resistance or the end resistance of the new pile with a smooth surface. Dominance of the sliding displacement along the pile–sand contact surface engenders the extremely small variation of the confining pressure of the soil around the new pileshaft. [Copyright &y& Elsevier]

Abstract: In this paper, particular attention was paid to the seismic enhancement effect of group-pile foundation with partial ground improvement method that is used for existing pile foundations in practical engineering. A model test on a full system with a superstructure, a nine-pile foundation and a sandy ground was conducted with the shaking table test device. The model pile is made from aluminum and the model ground is made from Toyoura Sand. The shaking table test device is 120cm in width and 160cm in length. The maximum acceleration is 1g and the maximum displacement is 5cm. The maximum payload is 16kN and the highest frequency is 10Hz. The model ground is carefully prepared to obtain a ground with controllable unified density. Before the shaking table test, the pattern of the partial ground improvement for an existed group-pile foundation is carefully selected using numerical tests with a 3D elastoplastic static finite element analysis. In the analysis, the nonlinear behavior of ground and piles are described by the cyclic mobility model (Zhang et al., 2007) and the axial force dependent model (AFD model) proposed by Zhang and Kimura (2002) can take into consideration of axial-force dependency in the nonlinear moment–curvature relations. The applicability of the numerical analysis has been verified in previous works by comparing the numerical results with a real-scale field tests (Kosa et al., 1998). Based on the results from the numerical tests on seismic enhancement effect of group-pile foundation with ground improvement, an optimum pattern of partial ground improvement of an existing pile foundations has been picked out for shaking table test. A numerical analysis using the program DBLEAVES (Ye, 2007) is also conducted for the same optimum pattern for comparison purposes. The effectiveness of the partial ground improvement method has been proved by both the shaking table test and the numerical analysis. [Copyright &y& Elsevier]

Abstract: The current analysis of rapid load tests (RLT) such as Statnamic is normally based upon empirical correlations with static pile tests in similar soils. In certain soil types, such as clays, the number of case studies used to develop analysis and allow selection of appropriate rate effect correction are limited. Due to these limitations, no distinction is made in the selection of correction factors between pile type and pile installation techniques. In clay soils it is well known that driven piles may have a significantly enhanced capacity over cast in situ piles of similar cross-section. To test the effect of pile installation techniques on RLT analysis, RLT testing and static testing were undertaken on precast driven concrete piles and cast in situ CFA piles installed in high plasticity London Clay. The results show that the installation technique does not appear to affect the magnitude of the rate effects, provided modifications are made to the analysis to account for the previously reported differences in static capacity between different installation techniques. Based upon the findings, it is suggested that a distinction should be made in RLT analysis between pile type and installation techniques, and for existing analysis techniques, further case studies based on rate correction parameters are required, especially in clay soils. [Copyright &y& Elsevier]

Anhand einer statistischen Auswertung dynamischer Pfahlprobebelastungen und zugehöriger Drucksondierungen wird ein neues Nachweisverfahren der vertikalen Tragfähigkeit für Spundwände vorgestellt, das in die 11. Auflage der EAU eingehen wird. Es wird gezeigt, dass die mittels Pfahlprobebelastungen ermittelte Gesamttragfähigkeit in nahezu allen Fällen die rechnerische Tragfähigkeit übersteigt. Das Nachweisverfahren wird hiermit der Fachwelt vorgestellt und diese wird aufgefordert, den Autoren Daten aus dynamischen Pfahlprobebelastungen und zugehörigen Drucksondierungen zur weiteren Validierung des Nachweisverfahrens zur Verfügung zu stellen. Revision of the verification procedure for vertically loaded sheet piles of the EAU. On the basis of statistical evaluations of dynamic pile tests and corresponding cone penetration tests, a new verification procedure for vertically loaded sheet piles is introduced. It is shown, that the real bearing capacity of nearly all tested sheet piles is higher than the calculated bearing capacity. By this paper, the new verification procedure is presented to the concerned professional's public. The authors encourage professionals to provide data of dynamic pile tests and corresponding cone penetration tests for further validation of this new approach. [ABSTRACT FROM AUTHOR]

The installation and extraction of jack-up spudcans may induce significant stresses in the adjacent piles supporting the permanent jacket platforms at an offshore site. In the present study, centrifuge model tests were conducted to investigate the effects of spudcan movements on the lateral and axial behaviour of adjacent fixed-head piles embedded in soft clay. Parameters such as jack-up operation period, clearance between the spudcan and pile, and the embedment length of the pile are examined. The test results show that the most critical period for platform piles is at the end of spudcan installation, and the lateral pile behaviour is more severely affected than the axial pile behaviour. During spudcan installation, the induced bending moment on a pile located one-quarter spudcan diameter away from the spudcan edge is about 2·4 times that of a pile located one spudcan diameter away. For a deeply buried spudcan with penetration of over three-quarters spudcan diameter, the induced bending moment on longer piles is much smaller than that on shorter piles. The experimental findings provide further insights into the underlying mechanisms governing spudcan-pile interaction in soft clay under various configurations and conditions. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Cyclic lateral-loading centrifuge tests were conducted on a new pile located at the center of 2×2 existing piles, to evaluate the effects of the existing piles on the new pile''s lateral resistance when the piles of an old building are left derelict. Furthermore, two-dimensional FEM analyses of the horizontal cross sections of the pile–soil systems were carried out. The centrifuge test results show that the lateral resistance of a new pile, located among existing piles, shows slight increases. The existing piles increase the horizontal subgrade reaction of the upper part of the new pile, but slightly decrease that of the lower part of the new pile. Numerical analyses reveal that the key to whether an existing pile increases the horizontal subgrade reaction of a new pile or not, is the soil displacement at the location of the existing pile. An existing pile increases the horizontal subgrade reaction of a new pile when the existing pile displacement is less than the soil displacement caused by the new pile. Conversely, an existing pile decreases the horizontal subgrade reaction of a new pile when the existing pile displacement is greater than the soil displacement caused by the new pile. [Copyright &y& Elsevier]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The authors respond to the comments made in their study "Shaft Resistance and Setup Factors for Piles Jacked in Clay." Topics discussed include the hypothetical lack of measurement of residual stress in the study, the lack of discussion on the development of residual stress and factors affecting it, and the differences between downdrag and pile setup in clay.

The author discusses the study "Instrumented Static Load Test on Rock-Socketed Micropile" by Hoyoung Seo and colleagues. Topics covered include the test borings conducted in the vicinity of the micropile test, the load test results and its interpretation and some further observations on rock sockets.

The authors discuss the study "Stresses Developed Around Displacement Piles Penetration in Sand" by Z. X. Yang and colleagues. Topics covered include the discussion's objective of showing that the limitation of discrete-element method (DEM) models is not as strong an impediment to obtaining meaningful stress fields as the authors of the study may have feared, the three scales in which the analysis is performed, and the use of a cone penetration test (CPT) in a virtual calibration chamber (VCC).

The article critiques the research that estimates the skin friction of piles which is embedded in consolidating clay and states that cohesion of saturated clay was not considered in the calculation method. Topics include the empirical methods used to predict skin friction of pile, and calculation of unit limit fs using numerical methods. It mentions graphs on the relationship between shear strength and depth of clay surface.

This discussion is based on the paper by Lu et al. (2013) [1] . In this paper, the authors have presented a theoretical study on the PS testing based on the ray path theory and the elastodynamic finite integration technique. This discussion offers some comments on the proposed method for determining the pile length, the ray path of the first P wave arrival for PS testing and analysis results of that paper under discussion. [ABSTRACT FROM AUTHOR]

The first part of this paper consists of brief introduction of the in-situ pile loading tests that have been conducted in Japan over the last two decades in connection with the design and construction of high-rise buildings in areas of soft soil deposits. In addition to the conventional types of tests in which the load is applied at the top and at the toe of the pile (O-cell test), what may be called "pile toe bearing test" and "skin friction test" is introduced. The results of these tests are described and compared with those from the conventional type of the pile loading tests. In-situ prototype tests are also introduced in which bearing power of Barrette type pile is compared with that of the circular type pile. A special case of in-situ pile loading tests conducted in Singapore is also introduced in which the friction between the circular ring-shaped concrete segment and the surrounding soil deposit was measured directly during excavation of the shaft by applying loads up and down by jacks installed between two adjacent segments in vertical direction. The second part of this paper is a brief description on constructions of large-diameter circular diaphragm walls that was carried out about 10 years ago for the LNG storage tank in the coastal site in Tokyo Bay. The construction of the large-scale Kawasaki Island in the middle of Tokyo Bay in Japan will also be introduced. The whole scheme and process of construction is for these two undertakings is introduced with some comments on observed behaviour of the walls and on special precaution taken during construction. [ABSTRACT FROM AUTHOR]

In this study, model pile tests were carried out in a custom-made pressurized chamber to explore the mechanisms of a driven pile setup in dry sand. A bender element system and tactile pressure sensors were used in parallel to monitor the stiffness and stress changes in the soil surrounding the pile during the test. The experimental results demonstrate that pile setup is not caused by the increase in at-rest radial stress . Instead, it is mainly attributed to the increase in radial stress during pile loading , as a result of soil aging (or creep). Pile installation pushes the surrounding soil to the side, thereby imposing additional loading on the soil inside the influence zone. This loading action initiates an associated aging (or creep) process during the setup period; the aging effects ultimately give rise to an increase in both and pile shaft resistance. The measurements also reveal that the increase in aging-induced soil stiffness is due to contact normal forces among soil particles gradually becoming more homogenized during the setup period. This suggested setup mechanism could explain the absence of pile setup in bored (nondisplacement) piles-the loading action induced by pile installation is too insignificant to trigger the required aging process. Using a similar logic, the mechanism could elucidate why the setup rate is higher in large-displacement piles than in small-displacement piles. [ABSTRACT FROM AUTHOR]