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The understanding of the complex soil–pile–raft interaction and their mobilization with the level of settlement is an important aspect for the performance-based design of the combined pile–raft foundation (CPRF). This paper investigates the influence of various interactions governing the load-bearing mechanism of a vertically loaded CPRF using a three-dimensional finite element-based computer program. The soil was modeled using the conventional Mohr–Coulomb elastic-perfectly plastic constitutive relationship and the drained condition was adopted in the analysis. Piles and raft were modeled using embedded beam elements and plate elements respectively. After successful validation of the developed numerical model, extensive numerical simulations were carried out considering a CPRF of different geometries and configurations where the foundation was subjected to incremental settlement boundary conditions. The variation of pile–pile, pile–raft and raft–pile interactions with settlement and their influence in dictating the loads induced within the foundation components were obtained. The analysis results indicated that the settlement levels played an important role in the mobilization of loads and dictating the efficiency of CPRF. Piles within a CPRF were able to mobilize their full capacity at the settlement of 1.5–2% of the raft width. The level of settlement and the spacing between the piles dictated the transition from negative interaction to positive interaction indicating a higher capacity of a CPRF compared to the combined capacities of piles and raft at higher settlement levels. Results suggested the operating settlement of CPRF which may be useful for geotechnical practitioners in making this foundation a cost-effective foundation choice. [ABSTRACT FROM AUTHOR]

A method for the estimation of the non-linear, time-dependent settlement of piled raft foundations (PRFs) embedded in saturated clayey soils subjected to uniformly distributed load under the single-drainage condition was developed. A total of 20 different rectangular PRFs resting on four different types of normally consolidated to moderately overconsolidated clays (overconsolidation ratios of 1, 2 and 5) were analysed to quantify their short- and long-term settlements. Rigorous three-dimensional, elasto-plastic finite-element (FE) analyses were performed with the critical-state-based modified Cam Clay soil constitutive model. Biot's coupled consolidation theory was used to model the time-dependent dissipation of excess pore pressure under the single-drainage condition. The FE analysis results were used to investigate systematically the influence of time and various soil and PRF parameters on the settlement responses of piled rafts. Fitted equations correlating PRF settlements and the degree of consolidation with various influencing parameters were developed. The proposed equations predicted the immediate and primary consolidation settlements and the degree of consolidation with reasonable accuracy and can be used in initial design stages. [ABSTRACT FROM AUTHOR]

Micropiles are small-diameter foundation elements that are widely used in building refurbishment to reinforce existing foundations or provide new foundations where access for construction is difficult. Thermally-activated (TA) micropiles could be useful as an efficient means of providing cost-effective ground-coupling when shallow geothermal energy systems are considered in building rehabilitation. It is well-established that thermal activation of pile foundations results in thermo-mechanical interactions between the pile and the surrounding soil. These thermally-induced effects need to be examined to ensure that they do not adversely impact the load transfer function of the micropile. Numerical analysis is able to produce reliable predictions of thermo-mechanical behavior of TA piles, and this study applied this technique to examine the cyclic thermal behavior of micropiles, isolated and in groups. For the situations considered in this study, it is shown that during cyclic thermal activation, irrecoverable movements are unlikely to be significant in design terms, if the initial mobilization of the shaft resistance is low. Though stable, cyclic thermal movement amplitudes are large enough that they should be considered in design. The study highlights that large changes in thermal stress can develop and be locked-in to the response of long flexible piles, and that these should be verified in design. Further, as pile spacing reduces, thermal interference results in a loss of heat exchange capacity per pile, which has to be considered in the design of large groups of TA micropiles. Therefore, TA micropiles can offer an efficient and secure means of providing ground coupling in shallow geothermal energy systems. [ABSTRACT FROM AUTHOR]

This paper aims to develop a relatively simple approach to examining the interaction among multiple foundation systems for closely spaced high-rise structures, termed here "urban forests", and to assess the extent to which this interaction can influence the foundation performance of a building within this "forest". To simplify the analysis and avoid undue numerical complexity, each foundation system is modelled as an equivalent pier, representing the deep foundations, the connecting mat or raft, and the soil contained within the piled raft system. The behaviour of a single equivalent pier is considered first, with the surrounding foundations being represented by an axisymmetric smeared ring outside the pier. After examining some general behavioural characteristics, a simplified approach using the concept of interaction factors is developed to facilitate estimation of settlement interaction between multiple adjacent foundations. The accuracy of this simplified approach is assessed via comparison with the axisymmetric approach. The significance of the interaction among foundations is examined for some simple cases. It is found that the settlement interaction depends largely on the characteristics of the foundations surrounding the building being examined. When all buildings are supported on foundations extending to a relatively stiff layer, the interaction effects tend to be relatively small. However, if one or more of the buildings is founded on a relatively short foundation system, interaction effects may be more significant. An example is provided to illustrate the application of the approach. [ABSTRACT FROM AUTHOR]

Role allocation during the development, update and utilisation of the specialized model subsoil – Recommendation No. 4 of the working group 2.14 (DGGT) "Digitalization in geotechnical engineering" Regarding the classical workflow in civil engineering, the responsibilities between geotechnical engineers, the client and other project partners like technical planners and construction companies are clearly defined and well established. In infrastructure construction, however, it will be prospectively obligatory that the geotechnical expert delivers a specialized model subsoil in addition to the geotechnical report. As this specialized model subsoil needs to be directly interconnected with other specialized models to build up the overall BIM model, the geotechnical expert will most likely be deeper embedded in the planning and construction process over the whole project life cycle. Furthermore, due to the need of standardization in the BIM process and the need to develop a suitable model structure for all specialized models, the client will also gain further responsibilities compared to the classical planning process. As an example, the clients have to define a clear and explicit model structure for the geotechnically related specialized models, too. This leads to an expansion as well as adaption of responsibilities throughout the project handling. Within this fourth recommendation of the DGGT working group 2.14 "digitalization in geotechnical engineering" the existing organizational structures within BIM projects are described and the responsibilities are defined focusing on the development of the specialized model subsoil. [ABSTRACT FROM AUTHOR]

This article is a summary of the available research works of cast‐in‐place deep‐seated bored piles in Myanmar. Instrumented static pile load test results are analyzed, discussed, and updated. The information contained in the article is mainly from the construction projects of private sectors constructed in Yangon and extended study of previous work on current practices of deep foundations and deep excavation Works in Myanmar. [ABSTRACT FROM AUTHOR]

The serviceability limit of the foundation system plays an important role in the safe long-term performance of a building. Under governing load cases in service life, the building foundation system should satisfy the serviceability limit state, i.e., total and differential settlement criteria. This study investigated the distress of a building through foundation performance assessment incorporating the soil–foundation–structure interaction (SFSI) effects. A spatially variable soil model [zonewise, obtained from field observation and electrical resistivity tomography (ERT) study] was used to obtain the settlement of the foundation system. Engineering properties of the subsurface were estimated from the collected soil samples and field tests. ERT result shows the variability of the subsurface layer. A three-dimensional finite-element model of soil, foundations, and structures was developed to estimate the settlement demand of the foundation and structures. The numerical model includes the geometric variability of all the foundations of the building and subsurface variability. Settlement and bearing capacity demand of the foundations were estimated and compared with the standard provisions. Results obtained show that the building foundation system satisfies the serviceability limit of the foundation system under total settlement criteria. However, the differential settlement of the system exceeds the required limit despite considering the SFSI effects, and is one of the major causes of distress to the building. The main contributions of this study also include establishing the spatial variability of the soil layer through ERT and correlating it with the crack zone in the building. [ABSTRACT FROM AUTHOR]

In piled raft foundations, the load shared between the piles and the raft is affected by a complex soil–structure interaction. However, the number of piles and their location can be optimised, thereby making piled rafts more effective and economical. In this study, the influence of three key design parameters (the number of piles, pile length and pile spacing) on pile–pile–soil and raft–pile–soil interactions was investigated; each of these parameters can lead to improvements in the performance and efficient load sharing of piled rafts. The results of small-scale model tests in sand showed that an increase in pile number or length proportionally decreased the load taken by the raft. A change in the pile spacing or compaction state of the sand bed also affected the raft's contribution, although to a lesser extent. Load sharing between the piles and the raft was found to be not only sensitive to the foundation size but was also dependent upon its settlement. Under favourable pile–pile–soil, raft–pile–soil and pile–raft–soil interaction effects, the combined load capacity of the piled raft increased. These interaction effects were non-linear and sensitive to settlement, which resulted in non-linear sharing of the load between the piles and the raft. The effect of pile inclusion and the number of piles on the shared load was also investigated using a simple hyperbolic model while considering the above interaction effects. [ABSTRACT FROM AUTHOR]

Piled-raft foundations are recognised for sharing the total load by both the piles and the raft. The economic benefits of this system lead to its popularity in practice; however, research in this field has continued to lag behind owing to the difficulties associated with modelling and availability of field data. This is due to the fact that the load-sharing mechanism of the piled-raft foundation is a complex soil–structure interaction problem, which is governed by the pile/raft/geometry/soil condition and by their by-product parameters. This paper presents the results of an experimental investigation on a prototype model of a piled-raft foundation in sand. The effects of the governing parameters on the load-sharing mechanism are examined. The results of this investigation show that pile spacing and settlement govern the load-sharing mechanism between the piles and the raft. A widely accepted analytical model in the literature was modified in this study to take into account the effect of settlements and pile spacing on the load-sharing mechanism in a piled-raft system. The theory developed is validated by the current experimental results and those available in the literature. The design procedure is presented as a guide in the design of the piled-raft foundation in sand. [ABSTRACT FROM AUTHOR]

A simplified analytical approach based on the non-linear pile–soil interaction model under vertical load is employed to analyse settlement of piled raft foundations. The accuracy of the simplified method is verified through comparisons with the results from previous research. Furthermore, according to the calculation results of various pile configurations, a simple empirical equation for estimating long-term settlement of a piled raft foundation is proposed. The prediction equation is validated through comparison with published cases. The comparison results show that the ratio of long-term settlement to immediate settlement increases linearly with the square root of the number of piles (at the same pile spacing), whereas the influence of the length/diameter ratio of the pile is small. The settlement ratio is approximately 2 for a piled raft foundation, and 1·5 for a raft or box foundation, and this may be useful for preliminary assessment of the long-term settlement behaviour of piled raft foundations. [ABSTRACT FROM AUTHOR]

Challenges in foundations for high‐rise buildings in glacially preloaded soils The economical and safe design of foundations for high‐rise buildings in Berlin requires a realistic assessment of the expected settlements for both the building itself as well as for existing neighboring structures. In this context taking account of glacial preloading and the corresponding increase of soil stiffness has a significant impact on the quality of the settlement prediction. In this paper different approaches to derive soil stiffness parameters are compared with regard to settlement measurements at various buildings in Berlin. It can be shown that stiffness values based on the correlations of EC 7‐2 significantly underestimate the in‐situ stiffness of the soil types encountered in Berlin. A more realistic reproduction of soil stiffness is possible with the stiffness values of TEV Gesteinseigenschaften and a stiffness approach developed by the authors. In these approaches soil density respectively soil consistency as well as the geological history of the soil layers with regard to glacial preloading are taken into account. [ABSTRACT FROM AUTHOR]

In architectural practice in Turkey, a high level overlap between the first design and the final product is not mostly seen. This may be resulted in poor performances (like aesthetical, functional) of buildings during the use phase. Also, buildings are influenced by such impacts as water, heat and sound in relation to their environmental conditions during their life cycle. Taking necessary measures against such impacts in the design phase is important for preventing problems that may arise during buildings usages. In addition to thermal insulation in Turkey, regulations on waterproofing and noise entered into force from the June 1, 2018. After this, water and sound insulation implementations in new buildings have become mandatory. This study, which is limited to the ‘Regulation on Waterproofing in Buildings’ and ‘Foundations’, includes a proposal using for the determination and control of the necessary waterproofing measures in the foundations of new buildings. It is envisaged that checklists can be used as a support tool for design and inspection in the period from design to usage. It is thought that the increase of similar list proposals for other building elements would be beneficial in reducing the breaks in the design and implementation phases of buildings. [ABSTRACT FROM AUTHOR]

When designing a project using piles, depending on the distance between them, the behavior of one interferes with the other. This interference occurs in terms of both the carrying capacity and the settlement ratio. Research on the group effect on typical Fortaleza soils is scarce, which justifies and prompts this work. The objective of the present investigation is to evaluate the group effect of piles excavated in a granular profile soil, typical to those that occur in the subsoil of the city of Fortaleza -Ceará- Brazil. For this, 26 piles were emplaced in a field located inside the campus of the Universidade Federal do Ceará (Campus experimental of Geotecnia and foundations of the UFC). Piles were isolated in groups of 2 to 4 piles, varying the distance between them. The subsoil was characterized by the collection of test results that were previously made in the sector. Additionally, a percussion drill excavation (SPT) was performed, with results of resistance indexes (NSPT) corrected based on efficiency estimates. Subsequently, static load tests (PCE) were performed on the groups of piles executed. It is verified that the piles worked only by lateral friction, and the group effect is observed in all the investigated spacings. [ABSTRACT FROM AUTHOR]

Foundation strengthening/new foundations to the historically sensitive structure of the Pergamon Museum on the Museum Island in central Berlin. The three‐wing building for the presentation of mostly large classical objects was built between 1910 and 1936 and after 100 years requires thorough refurbishment. In order to regain complete museum functionality and provide the correct climatic conditions for the exhibited objects, extensive strengthening measures, new foundations and lowering of the basement inverts are unavoidable. The extensive archived documents showed that the Pergamon Museum is founded at several levels at a depth of between 6 and 18 m below ground level. The deep geological scouring in the foundation formation led to great problems with the planned raft foundation after soil exchange under the protection of dewatering. The available results of the soil survey from 1912 in the area of the south wing, which until then had been built over, showed that the organic scouring extended down to about –12 m below sea level. This demanded a fundamental alteration of the foundation in this building section. Neither the dewatering plant nor the deep foundation elements available in 1912 were capable of reaching the loadbearing ground about 45 m below ground level. The stringent requirements for the deformation behaviour of the existing structures and in particular the south wing of the Pergamon Museum, which remained in use during the refurbishment works, required appropriate monitoring of reactions, which had to be constantly compared during the construction works. Both vibration and settlement curves were recorded and used as a decisive criterion for the selection of possible refurbishment technologies from specialised civil engineering. The solutions selected on site, both in the completion phase and in the current refurbishment phase, are described and discussed in this article. [ABSTRACT FROM AUTHOR]

Analytical and numerical solutions of the undrained load-carrying capacity of shallow foundations are mainly available for single foundations. This paper investigates the undrained limit states of two-spaced rectangular foundations with rigid connections. Three-dimensional finite-element analyses are carried out to systematically examine the coupled interaction of foundation spacing and degree of soil strength heterogeneity on the load-carrying capacity of the foundation systems under general loading. Results are presented in the form of ultimate limit states under pure vertical (V), horizontal (H), and moment (M) loads, and the failure envelopes under combined V-H, V-M, H-M and V-H-M loading. Soil failure mechanisms obtained from the finite-element analyses are shown for the representative loading paths of the two-foundation systems. Based on the failure mechanisms, the methods are established for calculating the undrained load-carrying capacity of the two-foundation systems to assist the foundation design in practice. [ABSTRACT FROM AUTHOR]

This paper describes the stochastic dynamic response of National Renewable Energy Laboratory 5 MW offshore fixed-based wind turbine (OWT) under various soil conditions - medium dense sand, stiff clay and layered profiles in 20 m depth of water. The aerodynamic and hydrodynamic OWT loads are derived using the force-controlled approach. Usually the OWT generates power in an operational regime and survives at extreme wind speeds. Therefore, two met-ocean conditions adhering to the irregular Joint North Sea Wave Project spectrum are considered - one in an operational regime (average wind speed Vw = 12 m/s, significant wave height Hs = 4 m and peak spectral period Tp = 10 s) and another in a near cut-out regime ( Vw = 22 m/s, Hs = 10 m, Tp = 14 s). The soil is modelled by way of a non-linear ground-to-spring model. For each sea state, time domain stochastic responses are calculated and the ensemble average response is calculated from 50 Monte-Carlo simulations. The change in ensemble average response due to changes in pile penetration depth and diameter of the piles for the three soil configurations is described. Results indicate that the dynamic response mainly depends on the stiffness of the soil and reiterate the need for detailed site-specific geotechnical investigations before designing OWT foundations. [ABSTRACT FROM AUTHOR]

As part of the Stuttgart 21 infrastructure project, German Railways is building a four-line railway bridge across the River Neckar in Stuttgart, work started in 2016. The Neckar railway bridge has an overall length of 345 m and has two abutments and six support axes. The structure crosses rail lines from the urban transit (Stadtbahn), the main trunk road B 10, inner city roads, the Neckar River, pedestrian and cycle ways as well as diverse public and private utilities. The bridge structure is located within the core mineral water protection zone, with its strict restrictions regarding the permissible depth of penetration into the subsoil and groundwater reservoirs. The mineral water springs lie within the construction site 26 m below the surface as artesian aquifers with an artesian pressure of ca. 10 m above ground level. From a groundwater management perspective, and following a program of five ground investigations and their evaluation, a raft foundation at the mid-level of the lower Keuper, built using cut-and-cover technique with a compressed air caisson, was chosen as the most economical foundation type for the three primary supports. A further programme of hydrochemical and geomechanical ground investigations was undertaken during the construction design phase. Following an evaluation of these additional ground parameters, it was possible to replace the compressed air caisson with a more economical deep foundation using large diameter piles. A management concept for possible scenarios was needed for the large diameter pile construction to achieve the required consent for exceptions from the ban on ground penetration in the area of the mineral springs. [ABSTRACT FROM AUTHOR]

About the influence of one-way loading on the bearing be haviour of precast concrete piles for onshore wind energy plants. Due to the energy transition several wind energy plants are built. Precast impact driven concrete piles represent one option to realise foundation piles onshore. In Germany, the bearing capacity of these piles can be estimated using empirical values taken from current standards or using in-house specifications of plant producers. Cyclic loading of such foundations exceeding 20 % of the static characteristic pile bearing capacity have to be considered when estimating the pile bearing capacity. However, the consequences of cyclic loading for the bearing behaviour of precast impact driven concrete piles are not fully understood yet. Therefore, field tests in cohesive and non-cohesive soils considering static and cyclic loading with different load amplitudes have been conducted and are presented within this paper. Using prevalent methods stated in current standards to estimate the bearing capacity of piles under static and cyclic loading are applied to recalculate the results of the field tests. Thereby, the suitability of these methods for estimation of the bearing behaviour of precast impact driven concrete piles under static and cyclic loading is reviewed. [ABSTRACT FROM AUTHOR]

The formula for calculating the ultimate bearing capacity of horizontal-vertical reinforced soil is investigated based on the failure mode and the mechanism of sand beds reinforced with horizontal-vertical reinforcement. Two components of soils and reinforcement are calculated separately. The ultimate bearing capacity of a shallow, concentrically loaded strip footing on homogeneous soil is commonly determined using the Terzaghi superposition method. The contribution of horizontal-vertical reinforcement is calculated based on the bearing resistance of the soil against the transverse members. A vertical inclusion is treated as a retaining wall, the confinement being calculated using Rankine's earth pressure theory. An analytical solution is presented including the traditional factors of soil, unit soil weight, footing width, number of horizontal-vertical reinforcement layers, and reinforcement geometry. The results were validated against experimental results and the mean error of the theoretical model was about 10%, with a maximum error of about 20%. [ABSTRACT FROM AUTHOR]

Monopiles are the most commonly used foundation type for offshore wind turbine (OWT) structures and are characterized by relatively large geometric dimensions, compared with offshore pile foundations typically used in the oil and gas industries. To date, there are no established technical guidelines tailored for the design and analysis of OWT monopiles. This paper first identifies various intrinsic drawbacks involved with the existing design and analysis methodologies as applied to OWT monopiles. Next, a comprehensive experimental program of 1g repeated lateral load tests, performed on a scaled rigid monopile installed in dry sand beds, is presented to investigate its behavior under various loading scenarios. The experimental results provide insights into the various blurry issues in the existing literature related to monopile behavior under long-term repeated lateral loading. Lateral soil resistance profiles were determined from the measured pile bending strain data and found to be markedly dependent on the degree of the polynomial function used for curve-fitting of the bending strain data. Finally, an experimental model is presented for estimation of the pile's accumulated rotation, which takes into account various basic characteristics of the applied lateral load cycles. [ABSTRACT FROM AUTHOR]

Difficulties in obtaining high-quality soil samples from offshore sites and heavy involvement of lab testing and engineering judgment have necessitated increasing reliance on in situ penetrometer tests, giving continuous penetration resistance profiles. This paper reports a framework for estimating spudcan penetration resistance directly from continuous resistance profile of a full-flow penetrometer (T-bar) test in single-layer clays and calcareous silts. The framework was validated chiefly against centrifuge test data, supplemented by some reported field data. [ABSTRACT FROM AUTHOR]

This paper presents the results of field tests performed to investigate the field behaviour of winged-monopile foundations. The principle of the winged monopile is that steel plates are attached to a standard monopile (in the area near the ground or seabed surface) to increase the foundation stiffness and lateral resistance. The experimental tests described in this paper consisted of load tested driven instrumented prototype scale standard (reference) monopiles and piles with varying wing geometries at two sand sites. The overall load-displacement performance and mobilised bending moment profiles were examined to assess the potential benefits of adding wings to monopiles. Experimental p- y curves were developed for the piles to analyse how the presence of wings influenced the soil-structure interaction of the foundation system. The use of simplified p- y methods for predicting the winged-pile response was assessed. The experiments proved that the addition of wings greatly improved the lateral resistance and stiffness of the piles; however, the results suggest that conventional p- y curve methods are limited as they cannot account for the effect that the enhanced stresses mobilised by the wings have on the strength and stiffness response of the pile below the wing location. [ABSTRACT FROM AUTHOR]

In a recent study, the time-dependent increase in axial load resistance of steel H-piles driven into cohesive soils, due to setup, was systematically quantified using measured field data. A method to estimate the setup based on measurable soil properties was subsequently established. These studies highlighted that the uncertainties of the measurements of soil properties and thus the semi-empirical approach to estimate setup are significantly different from those of the methodology used for measuring the pile resistance during retaps at any time after the end of driving. Recognizing that the two sets of uncertainties should be addressed concurrently, this paper presents a procedure for determining the factored resistance of a pile with due consideration to setup in accordance with the load and resistance factor design that targets a specific reliability index. Using the first-order second-moment method, the suggested procedure not only provides a simplified approach to incorporate any form of setup in design, but it also produces comparable results to the computationally intensive first-order reliability method. Incorporating setup in design and construction control is further shown to reduce foundation costs and minimize retap requirements on piles, ultimately reducing the construction costs of pile foundations. [ABSTRACT FROM AUTHOR]

Design of raft foundations on medium to dense sand is usually dictated by the allowable settlement rather than by a requirement to achieve an adequate margin against bearing failure. Piles are often installed under rafts to improve settlement performance, primarily the differential settlement, thereby to enhance structural performance. A practical design method has been developed for piled-raft foundations as a part of the Kinaxixi multi-use complex project in Angola; this is aimed at achieving an optimum pile configuration and is described in this paper. This method involves an iterative procedure to achieve consistency, with the design models representing the geotechnical and structural behaviours. The actual settlement of the raft is compared with the predictions as a means of validating the design method. [ABSTRACT FROM AUTHOR]

An experimental study of the formation of the soil heave plug inside a concrete caisson during installation in clay under suction is presented. The soil heave plug, the amount of caisson penetration and the vacuum pressure applied were measured during the model tests. The results show that the soil heave plug can completely fill in the cavity and prevent the caisson from penetrating further. The soil heave plug is affected by the geometry of the caisson. The higher the consolidation stress or the stiffer the soils, the higher is the suction pressure required, and a higher suction will in turn induce a greater soil heave plug. The m value, defined as the ratio of the volume of the soil heave plug to that of the penetrated caisson skirt wall, is adopted to evaluate the soil heave plug. The relationship between the m value and the undrained shear strength of the soil can be used to estimate the amount of soil heave plug and the caisson penetration for a concrete caisson with a wall thickness to external diameter ratio of 5% in normally consolidated clay conditions. [ABSTRACT FROM AUTHOR]

The lower bound depth of the self-weight collapse of loess is used to determine the type and grade of a collapsible loess foundation. It is important to select a reasonable foundation treatment depth and to determine negative skin friction neutral points of the pile. This study comprehensively analyses the differences between laboratory and full-scale field testing in determining the lower bound depth of the self-weight collapse of loess. Although this lower bound depth tends to be a unique value, obvious differences were obtained in the test results obtained by the two methods. Generally, the laboratory test results were 1·25-2·90 times greater than those of the field test, mainly owing to differences in saturation, test pressure, the sample stress state and soil non-uniformity. Evaluation of the lower bound depth of the self-weight collapse of loess should therefore be based on field testing and the results from laboratory tests need to be modified. This paper puts forward a new theoretical modification method for this purpose, which could reduce the differences between laboratory and field test results. [ABSTRACT FROM AUTHOR]

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The prime objective of this study is to look at the bearing capacity of a thin-walled spread foundation system in cohesionless soils. In this regard, laboratory-footing load tests were on the aforementioned footing in loose and dense sands. The Johor Bahru sand used is this study was dried and characterised in the laboratory. To investigate the beneficial effect of the thin walls on the bearing capacity of the footing, laboratory footing load tests were also conducted on a simple surface footing and the results were compared. For verification purposes, the experimentally obtained bearing capacities of thin-walled foundation were checked against finite-element analyses. The experimental findings show an enhancement of the bearing capacity by a factor of almost 2 when the thin-walled footing is used instead of a simple footing. The bearing capacities of the thin-walled footing in loose and dense sands predicted using finite-element analyses were different to the laboratory observations by 10%. [ABSTRACT FROM AUTHOR]

An increasing number of dams are being built on deep sand and gravel foundations. In this paper, the stress-deformation behaviour of a concrete-face rockfill dam built on sand and gravel foundation is studied based on in situ monitoring results and finite-element analysis. The effects of a dam construction scheme on the behaviour of the dam and its impervious structures are discussed. The stress and deformation values that were computed using the finite-element analysis model are consistent with the measured data. The monitored data and numerical results indicate that maximum settlement occurred at the bottom of the dam and maximum compressive stress is distributed in the foundation. The concrete-face rockfill dam built on the sand and gravel foundation exhibited good performance. The staged construction scheme of the dam caused uneven deformation and stress concentration in the dam body but could improve the behaviour of the cut-off wall to a certain extent. Moreover, several factors that influence the behaviour of the cut-off wall are analysed. [ABSTRACT FROM AUTHOR]

Wu, K.; Fan, Q., and Zheng, J., 2015. Effect of strength anisotropy on failure envelope of offshore shallow foundations under combined loading. The bearing capacity of offshore shallow foundations subjected to combined vertical, horizontal and moment loading is of interest particularly to the offshore geotechnical engineers. This paper reports a finite element (FE) study on the effects of strength anisotropy and foundation embedment depth on the combined bearing capacity. The Tresca failure criterion modified to allow for soil strength anisotropy and coupled with an elasto-perfectly plastic stress-strain relationship is assumed in the analysis which is conducted using the FE software ABAQUS. The undrained bearing capacities of shallow strip foundations under uniaxial vertical ( V), moment ( M) and horizontal ( H) loadings are predicted and compared with available solutions. The V- M- H capacity of embedded foundations under combined loading is represented by failure envelopes in H-M space for various vertical loading levels. The results presented in this paper show that the embedment ratio significantly affects the shape of the failure envelope expressed in terms of loads normalized by the pure moment or pure horizontal load-carrying capacity of the foundation. However, the shape of failure envelope defining the undrained capacity of shallow foundations under horizontal and moment loads is independent of soil strength anisotropy. [ABSTRACT FROM AUTHOR]

Ground movements observed during foundation installation and basement construction of a residential 53-story RC tower are presented. The One Museum Park West building is located in Chicago, Illinois, and was developed using a combination of bottom-up methods, used for the construction of a central concrete core of the building, and top-down methods to build five levels of basements. The excavation extended 13-15 m below grade and was made through soft to medium-stiff clays. The building was supported by drilled shafts and a perimeter wall formed by secant piles that transitioned to tangent piles below the bottom of the cut. The system was laterally braced with RC floor slabs structurally connected to the secant pile walls and the RC core. Field performance data were collected by means of settlement points and inclinometers located close to the walls on two sides of the excavation. The construction sequence and attendant ground movements during each main activity are summarized. As much as 160 mm of settlement was recorded in the adjacent streets throughout construction. Wall and foundation installation accounted for approximately 35% of the total settlements during construction, whereas top-down construction of the basement resulted in approximately 40% of the total settlements. These data emphasize the importance of considering all construction activities when making predictions of ground movements adjacent to deep supported excavations. [ABSTRACT FROM AUTHOR]

A new method for the evaluation of the ultimate load of piles by tests not carried to failure is proposed. It allows, by a proper use of the experimental results, a complete analysis of a pile behavior. In fact, the total, shaft and base load-settlement curves can be evaluated. It can be applied when shaft friction is fully mobilized during the test. [ABSTRACT FROM AUTHOR]

This paper reports advances in the prediction of spudcan resistance profiles during installation and preloading, based on the soil flow mechanisms observed in model tests and numerical analysis, and taking into account strain softening and rate dependency on the soil strength. Deep penetration of spudcan foundations was simulated for 14 case histories reported from different locations in the Gulf of Mexico, where the soils were single layer, predominantly normally to lightly overconsolidated clay. Axisymmetric and three-dimensional analyses were carried out using two large deformation finite-element (LDFE) approaches, modifying the simple elastic-perfectly plastic Tresca soil model to allow strain softening and strain-rate dependency of the shear strength. The field data were compared with the results of the finite-element analyses and with predictions using various design approaches. Excellent agreement was found, particularly when a mechanism-based design approach was used that differentiated between conditions before and after backflow of soil above the penetrating spudcan. [ABSTRACT FROM AUTHOR]

Successful waterproofing of concrete foundations prevents the degradation of environmental and health conditions and of building materials used in belowground stories and extends the service life of concrete constructions. However, despite the important role of waterproofing systems for concrete foundations and the fact that repairing them is either impractical or prohibitively expensive, there is very little useful information or discussion on membrane properties and the detailing required for a durable, watertight design. This paper presents a discussion of the requirements of waterproofing membranes and the auxiliary components used in waterproofing systems for concrete footings, mat-slabs, and pile foundations, along with a schematic representation of suggested systems and their detailing. Flexibility and mechanical resistance are particularly important and reasonably well-documented properties of buried waterproofing membranes, but knowledge of their long-term durability presently relies mostly on empirical data. The cost analysis of some of the suggested waterproofing systems revealed significant differences that, along with the other data presented, should aid building designers and contractors with the design and installation of effective waterproofing solutions for concrete foundations. [ABSTRACT FROM AUTHOR]

The design of spread footings on granular soils is generally governed by serviceability requirements. Recent studies have utilized databases of load tests to investigate the use of normalized load-settlement curves to model the behavior of footings on sands. A major limitation of available databases is that they are based primarily on data from plate load tests or footings that have an equivalent width smaller than 1.0 m. There is a need to confirm the applicability of these curves to footings of practical scale. The main objective of this paper is to update available normalized load-settlement curves using point measurements of settlement and load from full-scale footings. Bayesian techniques are employed in the updating process. Results indicate that the updated normalized load-settlement relationship is slightly more conservative but less uncertain than the current relationship. Results from an illustrative example involving serviceability limit state reliability analyses using footings with widths ranging from 1.5 to 3.0 m indicated that the updated relationship resulted in a slightly higher reliability level compared to the prior relationship. [ABSTRACT FROM AUTHOR]

The exposure of pier foundations owing to scour significantly reduces the foundation-bearing capacity and diminishes the flood-resistant capacity of a bridge. This paper proposes a nonlinear quasi-static analysis procedure for the performance of bridges with pile foundations under flow-induced loads for the evaluation on the flood-resistant capacity of scoured bridges. The Winkler beam model is adopted for the modeling of the pile-soil system, and the distributed hinge model is utilized to simulate the possible flexural failure of the piles. Soil springs with nonlinear curves are used to represent the nonlinearity of the supporting soil. To demonstrate this procedure, a case study on the Shuang-Yuan Bridge in Taiwan was performed for various flood and scour conditions. This bridge was partially demolished in a major flood event caused by Typhoon Morakot in 2009. According to the analysis results, a possible scenario for the failure of the Shuang-Yuan Bridge is presented, and the proposed method is shown to give a reasonable assessment of the flood-resistant capacity of bridges with scoured pile foundations. [ABSTRACT FROM AUTHOR]

Currently, it is understood that seismic responses of building structures could be changed, owing to the foundation flexibility. The present study is limited to evaluate such phenomenon on non-linear responses of reinforced concrete structures, emphasising their ductility demand distributions. To accomplish this objective, a set of three dimensional reinforced concrete generic frames were modeled as an assemblage of beam/column elements. Utilising substructure method, a set of linearly elastic spring-dashpot model was used to characterise the supporting soil. To estimate ductility demands, non-linear time history analyses as well as pushover analyses were conducted. The foundation-structure system was subjected to an assemblage of 'ordinary' and 'near-fault' ground motions. The results indicated soil-structure interaction effects mostly increase ductility demands of the flexible base structures. Consequently, neglecting this phenomenon may lead to erroneous conclusions in the prediction of seismic performance of flexibly supported reinforced concrete frame structures, especially when subjected to near-fault ground motions. [ABSTRACT FROM AUTHOR]

Difficulties are often encountered in a variety of seabed sediments during extraction of spudcan foundations of mobile jack-up rigs. This paper reports results from centrifuge model tests undertaken to provide insight into spudcan foundation behavior during vertical extraction through single, double, and multilayer soils. The model tests included half-spudcan tests against a transparent window, allowing the soil flow to be captured continuously by a digital camera and subsequently quantified through particle image velocimetry (PIV) analysis and separate full-spudcan tests to measure the uplift resistance. The observed soil-failure mechanisms provide insight with respect to the profile of extraction resistance. The mechanisms reveal evolving failure modes at different spudcan extraction depths and, in particular, changes in the failure patterns because of varying layer geometry, soil types, and properties. For single, double, and multilayer clays, suction at the spudcan base, shearing along a truncated cone above the spudcan, and weight of the soil above the spudcan constitute the extraction resistance. Maximum extraction resistance occurs in the stiffer soil layer. The extent to which suction is sustained at the spudcan base is critical in determining the extraction resistance. The presence of a sand layer beneath the penetrated spudcan, for example as part of the soil plug pushed down during spudcan penetration, allows the base suction to be released within a short distance of uplift and results in relatively low extraction resistance. Improved understanding of spudcan extraction mechanisms through layered soils resulting from this study will allow development of analytical solutions to model spudcan extraction behavior, assisting jack-up operators to plan properly for leg extraction based on seabed conditions. [ABSTRACT FROM AUTHOR]

An energy method for a linear-elastic perfectly plastic method utilising the von Mises yield criterion with associated flow developed in 2013 by McMahon and co-workers is used to compare the ellipsoidal cavity-expansion mechanism, from the same work, and the displacement fields of other research by Levin, in 1995, and Osman and Bolton, in 2005, which utilise the Hill and Prandtl mechanisms respectively. The energy method was also used with a mechanism produced by performing a linear-elastic finite-element analysis in Abaqus. At small values of settlement and soil rigidity the elastic mechanism provides the lowest upper-bound solution, and matches well with finite-element analysis results published in the literature. At typical footing working loads and settlements the cavity-expansion mechanism produces a more optimal solution than the displacement fields within the Hill and Prandtl mechanisms, and also matches well with the published finite-element analysis results in this range. Beyond these loads, at greater footing settlements, or soil rigidity, the Prandtl mechanism is shown to be the most appropriate. [ABSTRACT FROM AUTHOR]

A wide range of correlations have been proposed between cone penetration test end resistance, , and the ultimate end bearing pressure developed by bored piles. The value is typically related to the pile end bearing resistance at a normalised pile displacement equal to 10% of the pile diameter, , through a correlation factor, . While it is generally accepted that constant factors can be applied for the design of displacement piles, a combination of field tests and finite-element analyses of bored piles in sand has resulted in a myriad of design approaches, some of which suggest that varies with pile geometry, stress level and sand density. In this paper the results of finite-element analyses are presented which suggest that a constant factor can be adopted for the design of deep foundations in sand. [ABSTRACT FROM AUTHOR]

Fourteen calibration chamber tests were performed on one cylindrical pile and two tapered piles with different taper angles to investigate how the bearing capacity of tapered piles varies in relation to the soil state and the taper angle of the piles. The results show that the ultimate unit base resistance of a tapered pile increases when there is an increase in the mean stress, relative density and taper angle of the pile. The ultimate unit shaft resistance of the pile also increases as the vertical and horizontal stresses, relative density and taper angle increase. The results of the model pile load tests form the basis of a new design method for estimating the bearing capacity of tapered piles in sandy soil. The proposal is based on consideration of how the soil state and taper angle affect the bearing capacity of tapered piles. Field pile load tests were conducted on cylindrical and tapered bored piles in clayey sand to check the accuracy of predictions calculated with the new design method. A comparison of calculated and measured values shows that the new design method produces satisfactory predictions for tapered piles in sandy soil. [ABSTRACT FROM AUTHOR]

The response of a concrete arch dam is very much affected by the mechanisms of foundation rock behaviour. This type of dam is highly sensitive to displacements of its foundation owing to the low stiffness of the dam compared to the displacements of its foundation and abutments. Seepage is a load type which is distributed widely within foundation rock. Therefore, it could have important effects on displacements and stresses in the dam. In this paper, the Karun III double-curvature, 205 m high arch dam is selected as a case study. Effective stress analyses are carried out for the dam. The analysis results are compared with values recorded by instruments. Furthermore, the effects of some basic input parameters on the response of the dam are investigated. Subsequently, basic parameters are calibrated based on the initial investigation results, and the effective stress analysis is carried out for the Karun III dam by employing the modified parameters.fference in strain rate between the different tests. The deduced from the miniature vane was between 1·19 and 1·40 times that mobilised in quick-undrained TC of 38 mm diameter specimens under of 100 kPa. New methods of analysis are presented to estimate the strength contribution of the gel-like pore fluid to the mobilised , and also to determine more accurately the water content corresponding to the fall-cone liquid limit condition. The response of a concrete arch dam is very much affected by the mechanisms of foundation rock behaviour. This type of dam is highly sensitive to displacements of its foundation owing to the low stiffness of the dam compared to the displacements of its foundation and abutments. Seepage is a load type which is distributed widely within foundation rock. Therefore, it could have important effects on displacements and stresses in the dam. In this paper, the Karun III double-curvature, 205 m high arch dam is selected as a case study. Effective stress analyses are carried out for the dam. The analysis results are compared with values recorded by instruments. Furthermore, the effects of some basic input parameters on the response of the dam are investigated. Subsequently, basic parameters are calibrated based on the initial investigation results, and the effective stress analysis is carried out for the Karun III dam by employing the modified parameters. [ABSTRACT FROM AUTHOR]

The remarkable construction skills of the Inca are manifested in the superb site preparation, foundation design, and drainage of Machu Picchu. Decade-long field studies at the pre-Columbian archaeological site of Machu Picchu revealed that the Inca possessed the ability to prepare for structures that endure. This is evident in the vast amount of Inca construction that still exists for engineers to study and admire. Inca construction was sustainable because of their high standard of care, even in the absence of a written language, use of the wheel, or availability of iron or steel. This paper contains examples of good ancient site preparation, foundations, and drainage at Machu Picchu and details of a foundation failure and an ancient landslide. These examples serve to illustrate the site's challenging conditions for construction and the remarkable skills of the Inca engineers in addressing these difficulties. [ABSTRACT FROM AUTHOR]

Many of the older bridges in the United States have no original contract documents available, and about 26,000 bridges that are rated as scour critical have unknown foundation conditions. Thus, no information is available regarding the type, depth, geometry, or material of these scour critical bridge foundations. The unknown bridge foundations pose a significant problem to bridge owners because of safety concerns. This paper presents the determination of an unknown bridge foundation depth at Forth Worth, Texas. The bridge was supported by driven steel H-piles. Three nondestructive testing (NDT) techniques were utilized: (1) the parallel seismic (PS) method, (2) the sonic echo (SE) method, and (3) resistivity imaging (RI). The main objective of this present study was to compare the suitability of NDT techniques to determine the unknown bridge foundation depth. Based on the field test results, both PS and RI methods provided foundation depth close to actual foundation depth. However, the SE method was determined to be unsuitable for determining the unknown steel H-pile depth. [ABSTRACT FROM AUTHOR]

In the first part of the paper, hydro-geotechnical factors that must be taking into consideration, when choosing the foundation system for buildings located in urban centres, are listed. In the last part is presented a case study from Moldavia region, where due to some errors in the execution process, complex problems occurred. [ABSTRACT FROM AUTHOR]