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In projects such as highway bridges and offshore wind farms, understanding the kinematics of soil layers and their displacement is important for accurately predicting the behavior of caissons and monopiles under lateral loads. To better predict the distribution of soil deformation around the foundations, this paper presents an extensive usage of the energy-based variational method in laterally loaded deep foundations (caissons or monopiles) with very large diameters. By adding an assumption of soil deformation in multilayered soils, the displacement distribution around the foundations can be better described. The responses of deep foundations were obtained by minimizing the potential energy and virtual work of the foundation-soil system. After that, static lateral loading tests on two caissons with the same embedment depth of 36 m and the same diameter of 6 m were performed, and the displacement field in soils and the deflection profiles of the caissons were measured. Results show that the lateral displacement and the decay distribution fields calculated from the theory in this paper agree with the measured data from the static loading tests and the corresponding finite differential method (FDM) results. At last, a series of case studies performed by MATLAB and FDM analyses were also conducted to study the influence of uz on the response of foundations, as well as the influence of foundation parameters and soil modulus on the value of ϕz. [ABSTRACT FROM AUTHOR]

A laboratory model of a single pile embedded in Nanyang expansive soil and subjected to water infiltration is applied in this study to examine the interaction between the expansive soil and pile foundation upon water infiltration. The soil matric suction decreases as a result of the rising soil-water content. The amount of soil ground heave reaches its peak of 10.7 mm after 200 hours of water infiltration. As matric suction decreases, pile shaft friction also declines, which causes more of the load at the pile head to be carried by the pile base resulting in more pile settlements. A new numerical simulation method is provided to simulate this issue by coupling the subsurface flow, soil deformation, and hygroscopic swelling to investigate the expansive soil-pile response upon water infiltration. From the numerical simulation model, hygroscopic strain arises as a result of elevated moisture levels resulting from the entry of water, and due to ground heave and the mobilization of lateral soil swelling, the shear stress at the interface between the soil and the pile gradually increases over time. It reaches its maximum value of 4420 Pa at upper depths around 200 hours after the infiltration. The comparison between the lab model testing data and the numerical model results demonstrates a good level of concurrence. [ABSTRACT FROM AUTHOR]

In order to investigate the sensitivity of weak soil parameters on the deformation of balanced double-row piles, a case study was conducted in a deep foundation pit project in Shenzhen City. A variety of analysis methods, including numerical simulation, field measurements, orthogonal experiments, and theoretical analysis, were employed to analyze the impact of three weak soil parameters on the deformation of balanced double-row piles. The research results showed that the deformation of the front and back rows of piles exhibited overturning deformation, gradually decreasing with depth and reaching the maximum at the pile top due to the constraint effect of the balance platform. The numerical simulation results of horizontal displacements for the front and rear piles were in good agreement with the field measurements, confirming the accuracy and reasonableness of the numerical analysis model and parameter selection. Through a series of orthogonal numerical simulation experiments, it was determined that the cohesive strength (C) of soft layers, such as rockfill and silt, is a key factor, the internal friction angle (φ) is an important influencing factor, and the elastic modulus (E) is a general influencing factor. Theoretical analysis was employed to establish the relationship curve between each parameter and the maximum pile deformation, as well as the sensitivity factors, further verifying the impact of these weak soil parameters. The research findings presented in this paper can provide valuable guidance for geotechnical engineers when selecting geological parameters for similar deep excavation projects. [ABSTRACT FROM AUTHOR]

In this paper, a general power form of head-loss (pressure-drop) equation and the concept of shear velocity were used to study non-Darcy filtration through coarse granular materials. Using new laboratory data, the validity of four widely-used power form pressure-drop equations were evaluated. The results indicated that for the lower size of grain diameter (d ≤ 8.7 mm) the Wilkins (in: Proceedings of the 2nd Australia-New Zealand Conference on Soil Mechanics and Foundation Engineering, Christchurch, 1956) method has predicted satisfactorily the hydraulic gradient, while for the higher size of grain diameter (d ≥ 15.6 mm), the Stephenson (Rockfill in Hydraulic Engineering, Elsevier Science Publishers B.V., Amsterdam, 1979) method predicted acceptably the pressure gradient. The results also indicated that the best estimation for the Izbash coefficient a is the Wilkins method. Finally, new correlations for friction factor, shear velocity and Reynolds number as well as new threshold limits for Darcy, partially-turbulent, and fully-turbulent flow regimes are presented and discussed. [ABSTRACT FROM AUTHOR]

Hydraulic heave in round excavation pits with relief boreholes – calculation approach The use of relief boreholes to reduce the effect of a vertical upward flow has proven to be a constructive measure to avoid the risk of hydraulic heave in excavation pits in groundwater. The applicable standards and regulations, however, only provide general information on the use of relief boreholes. A concept for the verification against hydraulic heave failure using relief boreholes is missing as well as defined information on the arrangement of the relief boreholes and the influence of the excavation geometry. Therefore, the aim of the research work at the Chair of Geotechnical Engineering of RWTH Aachen University was to develop a concept for the proof against hydraulic heave failure with the arrangement of relief boreholes. The result was a calculation approach that determines the decisive fracture body under consideration of the flow conditions due to the relief boreholes. This fracture body can then be used for the proof against hydraulic heave failure. Based on this, dimensioning diagrams were finally generated for typical excavation pit geometries in dimensionless representation. [ABSTRACT FROM AUTHOR]

Existing projects indicate that a large number of pile boreholes formed via cement fly ash gravel (CFG) pile construction in soft soil could produce a borehole group effect in the absence of timely backfilling. The borehole group effect could cause ground settlement and threaten the safety of adjacent buildings, tunnels, and pipelines. However, the mechanism of the borehole group effect, causing serious deformation in surrounding soil, has seldom been studied, and there exists no simple simulation method to predict the borehole group effect. In this study, a case involving CFG pile boreholes in a soft soil area causing a significant settlement of surrounding buildings was introduced. Based on this case, a centrifuge test was designed to simulate the influence of a single borehole and multiple boreholes on the surrounding soft soil. The mechanism of the borehole group effect was investigated via centrifuge tests and the finite-element method. In the case of a single borehole, a horizontal circumferential stress arch and vertical stress transfer arch were formed in the soil, which effectively limited the shrinking deformation of the borehole wall. In the case of a large number of boreholes with a small spacing, the horizontal and vertical stress arches around the boreholes affected and weakened each other. As a result, the shrinking deformation of the borehole group was greater than that of the single borehole. In other words, the borehole group effect was found to cause serious deformation in the surrounding soil. To overcome the difficulty in the simulation of a large number of pile boreholes in engineering, the borehole-type conversion and multihole merging method was proposed. The simulation results indicated that the simplified method was reasonable. [ABSTRACT FROM AUTHOR]

The article presents the discussion on applicability of this new plasticity chart to several soils containing diatoms with unique particle morphology and porous structure. Topics include confirms the effectiveness of the new plasticity chart, which allows soil classification to be conducted based on FIc from the fall-cone test as an alternative to the plasticity limit from the thread-rolling test; and increasing high fluid holding capacity due to the intra-skeletal porosity of diatoms.

In order to reduce the influence of underground space development on the surrounding environment, deformation of supports should be strictly controlled in the construction of deep foundation pits in soft soil area. Based on the excavation of a deep foundation pit in the soft soil area of the Changjiang River floodplain, typical stress path tests considering the foundation pit's excavation process were carried out for undisturbed soil samples. The law of stress deformation of soil during excavation is analyzed, and the calculation parameters of Ohta-Sekiguchi constitutive model are determined. A three-dimensional finite element model that takes into account the construction process is built to numerically simulate of the bottom-up construction method, the top -down construction method and the integration of bottom -up and top -down construction method. The displacement of the foundation pit cut with the method integrating bottom-up and top-down construction is analyzed, and the calculated deformation of the supporting structure and the foundation pit soil with the method integrating bottom-up and top down construction is compared to the observed values. The influence of the three different construction methods on the horizontal displacement of diaphragm walls, deformation and displacement of soil around the foundation pit and the constructionduration is analyzed and compared. Compared with the bottom-up construction method and the top-down construction method,the integration of bottom-up and top-down construction method can control the deformation of a foundation pit in the soft soilarea of the Changjiang River floodplain, and has the advantage of construction period and cost. [ABSTRACT FROM AUTHOR]

The main reclamation works of Hong Kong International Airport three runway system project uses the method of backfilling the sea area to form a new artificial island. The subsoil foundation of the project area is soft silt soil. The large deformation of the soft foundation during the backfilling process is one of the technical difficulties of the project. Because the artificial island seawall is affected by the dredging force or the compression force of the soil when backfilling. It will have hidden danger and a higher risk of instability and damage. This paper focuses on the deep foundation soil deformation of the artificial island seawall as the research object and adopts the advanced automated monitoring method through the Shape Acceleration Array (SAA） instrument to monitor the deep soil deformation of the seawall. It would also compare the monitoring results of the SAA with the monitoring data of the traditional manual inclinometer. The application value of SAA in engineering monitoring is verified, and the advantages and application prospects of this monitoring method are analyzed and summarized. [ABSTRACT FROM AUTHOR]

A hand-calculation method for estimation of nonlinear load–settlement response of piled raft foundations (PRFs) embedded in sandy soils is developed using three-dimensional finite-element (FE) analysis in which the elastoplastic constitutive behavior of the soil is modeled using the unified Clay And Sand Model (CASM). Three types of PRFs with rectangular, strip, and circular rafts and with a variety of pile dimensions and arrangements are considered in the study. The PRFs are assumed to be embedded in five different sands (Ottawa sand, Erksak sand, Sacramento sand, Portaway sand, and Decomposed Granite sand) with different elastic properties, critical state parameters, and relative densities. Systematic parametric studies are performed to develop equations for the estimation of the average nonlinear settlement of PRFs. The maximum and differential settlements are also estimated from the average settlement. The proposed equations require the relative density, elastic constants, and critical state friction angle of sand, and the piled raft geometry and properties as inputs. The settlement equations are applicable to PRFs of sizes similar to those considered in the study and can be used by practitioners for quick, initial estimation of PRF settlement as part of design calculations. [ABSTRACT FROM AUTHOR]

Settlement prediction in soft soil foundation engineering is a newer technique. Predicting soft soil settling has long been one of the most challenging techniques due to difficulties in soft soil engineering. To overcome these challenges, the wavelet neural network (WNN) is mostly used. So, after assessing its estimate performance, two elements, early parameter selection and system training techniques, are chosen to optimize the traditional WNN difficulties of readily convergence to the local infinitesimal point, low speed, and poor approximation performance. The number of hidden layer nodes is determined using a self-adaptive adjustment technique. The wavelet neural network (WNN) is coupled with the scaled conjugate gradient (SCG) to increase the feasibility and accuracy of the soft fundamental engineering settlement prediction model, and a better wavelet network for the soft ground engineering settlement prediction is suggested in this paper. Furthermore, we have proposed the technique of locating the early parameters based on autocorrelation. The settlement of three types of traditional soft foundation engineering, including metro tunnels, highways, and high-rise building foundations, has been predicted using our proposed model. The findings revealed that the model is superior to the backpropagation neural network and the standard WNN for solving problems of approximation performance. As a result, the model is acceptable for soft foundation engineering settlement prediction and has substantial project referential value. [ABSTRACT FROM AUTHOR]

In this paper, the influence of the foundation configuration (raft or separate footings) on tunnel–soil–framed building interaction is investigated using geotechnical centrifuge testing. Tunnelling-induced soil movements and deformation fields, framed building displacements and structure shear distortions (with associated modification factors) are illustrated. Framed building stiffness and footing bearing capacity are also evaluated experimentally. Results show that the foundation configuration plays an important role in determining the ground response to tunnelling, affecting soil displacement fields, as well as the distribution of soil shear and volumetric strains. In particular, foundation settlements and differential horizontal displacements are larger for separate footings compared to raft foundations. The effects of building width, weight and eccentricity (with respect to the tunnel) on foundation settlements and structural distortions are quantified for separate footings and contrasted against results for raft foundations. The modification factor of the maximum building shear distortion is linked to the relative soil–building shear stiffness; interestingly, for buildings with similar values of relative stiffness, the level of shear distortion within framed buildings is lower for separate footings than rafts. [ABSTRACT FROM AUTHOR]

A constitutive model that can accurately predict the behavior of the soil-structure interface is beneficial to the analysis and design for foundation engineering performance. This paper develops a new model with the nonlinear approach for simulating the monotonic and cyclic behaviors of the granular soil-structure interface. Based on the hyperbolic function, the concept of normalized shear displacement is proposed, and the basic model for the effects of the normal stress, the nonlinear shear modulus, and the friction angle on shear strength during shearing is deduced. On this basis, the Pyke criterion is modified to describe the cyclic loading responses. The relation between the friction angle and the state parameter of the interface in different interface states is established under the framework of critical state soil mechanics (CSSM) theory to further reflect the interface behaviors corresponding to the changes of void. Taking the phase transformation state as a reference state of volume increment, the incremental equation of stress-dilatancy induced by shearing is developed. In addition, the basic model is extended to be able to describe the interface mechanical behaviors under constant normal load (CNL), constant stiffness (CNS), and constant volume (CV) conditions by considering the characteristics of three typical stress loading paths. Only 10 calibrated parameters are required to reproduce the complex properties in the monotonic and cyclic behaviors. The predictive performance of the proposed interface model is examined by the previous experimental results. [ABSTRACT FROM AUTHOR]

Nowadays, information about geotechnical parameters and future stability of soil is highly demanded by geotechnical laboratories and companies. The use of geotechnical information systems integrated in a GIS offers a better manipulation of the geotechnical parameters of different sites for a general exploitation of storage, manipulation, management and analysis of geotechnical data. The aim of the current research is to present the results of studies developed to set up a geotechnical database for Algiers region using «Géo-Base» information system developed within the framework of this research and integrated in a GIS through a descriptive statistical analysis of mechanical and geophysical identification parameters of velocity measurements collected from 1200 survey profiles located on 80% of the surface of the region. The visualization of geotechnical maps of bearing, consolidation, settlement, swelling of soils at any depth of Algiers region are obtained by manipulating the system technology produced as part of this research. These results are very helpful to builders, planners, researchers and engineers in their future work; they will help them making better decisions and producing safer and more economical designs. Furthermore, this research allows establishing the first geotechnical map of Algiers region. [ABSTRACT FROM AUTHOR]

Piled raft foundations are the composite construction of a spread foundation and a few number of piles that are usually used in soft soils to compensate the weakness of a raft in satisfying the design requirements. Due to the complex behaviour of piled raft, it is necessary to take into account a number of factors such as pile geometry and arrangement, raft thicknesses, soil properties and loading condition in the design. In this study, a parametric study has been conducted by a three-dimensional finite-element method considering the full interaction between the components of piled raft foundation. The underlying soil consists of Babol clay in drained condition with various stiffness and plasticity, determined from the results of a geotechnical investigation. The results of numerical analyses show that the bearing capacity of piled raft obviously increases with increasing pile length, pile spacing and raft thickness, especially in stiff clay. The effect of load type is more significant for the differential settlement and pile loads than other parameters. Finally, the advantages of using an optimum design method are examined in a special case of analyses and a case history. [ABSTRACT FROM AUTHOR]

The accuracy of the default Federal Highway Administration (FHWA) simplified model for estimation of facing tensile forces for soil nail walls under in-service conditions was evaluated using a large quantity of measured long-term and short-term facing tensile force data collected from the literature. The estimation accuracy was quantified by the mean and coefficient of variation (COV) of the bias where bias is defined as the ratio of measured to calculated facing tensile force. Based on the available data, the default FHWA simplified model equation was found to overestimate long- and short-term facing tensile forces by about 15% and 23% on average, respectively. The corresponding spreads in estimation accuracy expressed as the bias COV were about 43% and 67%. Undesirable correlations between bias values and calculated facing tensile forces using the default FHWA simplified model equation were detected. A modified FHWA simplified model was proposed to improve the on average accuracy, reduce the spread in estimation accuracy, and remove the hidden correlations noted above. In addition, the modified equation has fewer empirical coefficients than the current formulation (i.e., four versus five). The facing tensile force equations developed in this study are a contribution to the design of facing of soil nail walls within the current FHWA soil nail wall design framework. [ABSTRACT FROM AUTHOR]

Full-scale load tests are usually conducted to obtain the reliable soil resistance at the site and to determine that the foundation is capable of sustaining working loads with sufficient safety. The aim of this study is to evaluate the interaction between test pile or barrette and the reaction system using the finite element code Plaxis 3D. The results show that the interaction between the test pile and reaction piles is more important than that between the test barrette and reaction barrettes. In addition, the results indicated that the interaction phenomenon depends on the pile slenderness and on the spacing between the test pile or barrette and the reaction system. [ABSTRACT FROM AUTHOR]

Prediction of displacement demand to assess seismic performance of structures is a necessary step where nonlinear static procedures are followed. While such predictions have been well established in literature for fixed-base structures, fewer bodies of researches have been carried out on the effect of rocking and uplifting of shallow foundations supported by soil, on such prediction. This paper aimed to investigate the effect of soil structure interaction on displacement amplification factor C1 using the beam on nonlinear Winkler foundation concept. A practical range of natural period, force reduction factors, and wide range of anticipated behavior from rocking, uplifting and hinging are considered and using thousands nonlinear time history analysis, displacement amplification factors are evaluated. The results indicate that the suggested equations in current rehabilitation documents underestimate displacement demands in the presence of foundation rocking and uplift. Finally, using regression analyses, new equations are proposed to estimate mean values of C1. [ABSTRACT FROM AUTHOR]

Results of laboratory tests on geocell-reinforced soils indicate negligible change in the internal friction angle and development of an apparent cohesion. If sufficient apparent cohesion to withstand applied loads on foundations can be determined, then a suitable kind of soil-geocell composite may be selected among pretested ones by laboratory means. In the present study, using numerical methods of lower bound limit analysis, the required apparent cohesion in the geocell layer to bear the applied load on strip foundations has been determined by back analysis. Effects of contributing factors were evaluated on the results for single and double layer reinforcements. [ABSTRACT FROM AUTHOR]

This paper focuses on the development of a new non-linear macro-element for the modelling of soil-foundation interaction. Material and geometrical nonlinearities (soil yielding and foundation uplift respectively) are taken into account in the present macro-element to examine the response of shallow foundations under monotonic and cyclic loads. Several applications of soil-foundation systems are studied. The results obtained from these applications are in very favourable agreement with those obtained through other numerical models in the literature. [ABSTRACT FROM AUTHOR]

A method is developed for calculating the settlement of single double-bladed metallic screw piles in clayey soils for the foundations of temporary buildings. The method is based on the use of a patented design of a screw double-bladed pile and takes account of the nonlinear load dependence of its settlement. It is established that for clayey soils with semi-solid consistency the discrepancy obtained between the experimental final settlements of double-bladed screw piles and the computational data obtained by the proposed method does not exceed 20-30%. [ABSTRACT FROM AUTHOR]

This paper presents a case study of investigating damages in existing building adjacent to foundation pit in construction, in which the settlement influence of adjacent building induced by constructing foundation pit is demonstrated by means of field observation, numerical analysis and experimental investigation. This study focuses on the principal cause inducing these damages in the existing building. This work demonstrates that the stratum settlement of the existing building during excavating foundation pit are significantly influenced by not only construction task of excavating soils but also that of dewatering soil mass in constructing foundation pit, since the principal constitution of fine sand and medium sand in the sludge can be easily run off with stratum loss during the dewatering task, and the hydraulic connection between the inside and outside of the foundation pit thus can't cut off using underground continuous wall, which can probably produce structural damage of soil mass with stratum settlement. [ABSTRACT FROM AUTHOR]

In this paper we investigate the effect of pile group geometry and loading direction on the ultimate lateral soil resistance developing on a tripod foundation, using numerical and analytical upper bound methods. Two distinct kinematic mechanisms are established, corresponding to different failure modes associated with wide and narrow pile spacing. A comparison of tripod group performance against other common pile group layouts suggests that the former results in optimal efficiency for cases when the direction of the lateral load is unknown, such as the foundation of offshore structures subjected to wind, wave and ocean current loads. [ABSTRACT FROM AUTHOR]

In this research, a reinforcement mechanism for shallow foundations is determined through laboratory model tests and numerical analyses. The numerical analyses are performed with the finite element program FEMtij-2D using the elastoplastic subloading tij model. The frictional behavior between the reinforcement and the ground is simulated using an elastoplastic joint element. Several tests were performed whereby the installation depth, length, roughness, and fixity conditions at the edges of the reinforcement were varied. Results show that the effectiveness of the reinforcement and the bearing capacity of the reinforced ground depend on the position, length, roughness, and fixity condition of the reinforcement. A significant increase in the bearing capacity can be achieved if the geosynthetics are properly placed at an optimum length with the boundary fixed to the ground. The effect of the loading position is also investigated because in reality the load on a foundation does not always act at the center of the foundation. The numerical results accurately describe the experimental results; the simulations accurately account for the mechanical behaviors of both the soil and reinforcement and the frictional behavior between them. Therefore, the simulation technique can be used to predict the bearing capacity of reinforced ground. [ABSTRACT FROM AUTHOR]

Cone Penetration Test (CPT) data are often used directly in the design of shallow and deep foundations and many other applications. To produce more cost-effective designs, it is advantageous to use CPT data to establish stratigraphic profiles as well. Algorithms to generate a stratigraphic profile using data from an individual CPT sounding and a Soil Behavior Type (SBT) chart as inputs are presented. Two SBT charts from the literature were selected and modified to eliminate ambiguity in soil classification. Novel algorithms were developed for handling the occurrence of thin layers within a stratigraphic profile to account for the fact that the standard CPT cone cannot accurately sense layers with thickness below a certain limit and a representative cone resistance cannot be obtained if the layer is too thin. Likewise, the algorithms prevent the creation of a soil profile with adjacent layers of essentially the same soil by consolidating layers appropriately. The algorithms presented generate a design soil profile, produced using a precise classification based on soil type and state and by elimination of artificial layering, that can be more effectively used in design. [ABSTRACT FROM AUTHOR]

Predicting the bearing capacity of a spudcan foundation under combined vertical ( V ), horizontal ( H ) and moment ( M ) loads is a challenging problem encountered by geotechnical engineers. In previous studies the combined VHM capacity was defined for a uniform soil profile, ignoring any variability in soil stratification and properties. In offshore conditions, however, both the soil profile and soil properties vary spatially. Therefore, it is of interest to account for the spatial variability of soil in the analysis of the bearing capacity of a spudcan. It is shown in this paper how the spatial variability of a clay affects the bearing capacity of a deeply buried spudcan foundation under combined loadings. Three-dimensional random fields are generated to model the spatial variability of undrained shear strength of clay and combined with a non-linear finite element analysis to investigate and define the VHM failure envelope of a spudcan foundation. Because of the random nature of soils VHM failure envelopes of different probability of occurrence are proposed. Results from this study provide guidance to the practical assessment of spudcan foundations in spatially varied soil conditions that can be encountered offshore. [ABSTRACT FROM AUTHOR]

Methods are proposed for evaluating the 'pump-up' of the lateral soil pressure by the surcharge of supported soil mass and taking account of this 'pump-up' in calculations of bulwarks with stabilization of the filling soil. [ABSTRACT FROM AUTHOR]

A static solution is offered for the problem of the stability of a smooth freestanding sheet pile wall. The limiting stress state of the soil surrounding the sheet pile wall is determined by way of statics-based theory of limit equilibrium of soil. On the basis of this method, a practical technique is proposed for calculating the depth to which a dowel is lowered into a trench. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to establish a complete analytical solution concerning the linear pressure distribution under rigid rectangular spread footings. An eccentricity diagram is developed to map the unique footing deformations and compression zones in each one of five distinct regions. For each region, the linear soil pressure, neutral axis position, and pressure values at the four corners are expressed in closed forms. The accuracy and consistency of the explicit expressions are verified by presenting several special boundary cases, whereas the physical interpretation is brought out by analyzing the eccentricity diagram. A generic nomogram providing the maximum soil pressure is also formed to promote efficient structural footing design. The developed analytical formulas for responses and resultants enable algorithmic implications without iterations and offer high computational efficiency. Proper examples, generated via developed computer software, exhibit how the theoretical content of this article is applied in practice. The software enables three-dimensional (3D) viewing of the deformed and undeformed physical and mathematical model of the structure, allowing detailed visual inspection of the results. [ABSTRACT FROM AUTHOR]

This paper studies the dynamic interaction between two or more adjacent foundations resting on the surface of a stratified soil. The precise integration scheme adopted ensures that the numerical results obtained are highly accurate. Only the interfaces between the foundations and the soil need to be discretized and there is no limit on the thickness or on the number of soil layers to be considered. Numerical examples are provided to verify the accuracy and computational stability of the proposed approach. A series of parametric studies have been carried out to clarify the effects of layer depth, soil damping, spacing between adjacent foundations, masses and moment inertias of supporting structures and the wave propagation velocity on the dynamic behavior of three-dimensional (3D) foundation-soil-foundation interaction (FSFI). [ABSTRACT FROM AUTHOR]

The paper presents the results of an integrated investigation of the interaction of adjacent foundations with the subsoil. A method is proposed for analyzing the settlement of adjacent foundations that arise as a result of their interaction. Comparison of the theoretical and experimental data demonstrated an acceptable reliability of the proposed method. [ABSTRACT FROM AUTHOR]

A failure prediction of cracking possibilities of buried foundation sections is studied basing on databases issued from stochastic modeling of soil geomechanical properties, which represents the support of a part of foundation system. The mechanical behavior of cracked foundation sections resting on soil of random geomechanical properties is well described using Line Spring Model. Numerical model is solved by the method of exact series solutions in structural mechanics for the computation of foundation structural responses at the crack tip and normalized stress intensity factors (SIF) within reasonable accuracy. The effects of the crack position, crack length and probabilistic assessment of soil geomechanical properties are discussed in this present a paper, especially on the evolution of normalized stress intensity factors and foundation structural responses. A parametric study based on the obtained numerical results of SIF of cracked foundation has been carried out in order to have a suitable prediction of failure occurrences at critical sections. These structural predictions can be very useful to direct engineers and researchers to take optimal solutions to improve the structural reliability of cracked foundations especially the ones of strategic parts of industrial and petrochemical infrastructures. [ABSTRACT FROM AUTHOR]

In the present paper, the response of cylindrical storage tank foundation resting on stone column-reinforced ground has been studied considering the separation between the bottomraft and ground under liftoff condition. The bottomraft of the tank is idealized by a circular plate. The stone column-reinforced ground ismodeled as a tensionless foundation. Soft foundation soil and granular fill are idealized as a spring-dashpot element and Pasternak shear layer, respectively. Stone columns are modeled as stiff nonlinear springs. The stone columns are converted into equivalent concentric rings with one stone column at the center to simulate the axisymmetric condition for the analysis. The governing differential equations are derived fromthe classical theory of thin plate and solved using the finite-difference technique. A parametric study is performed to investigate the differences between the response of tensionless and conventional elastic foundation systems. It is observed that tensionless foundation idealization is essential to analyze the liftoff and avoid erroneous design of the raft for the cylindrical storage tank. Recommendations are also suggested to avoid possible liftoff. [ABSTRACT FROM AUTHOR]

According to the similitude theory, a 1-g physical model test for soft ground with deep mixed columns was conducted. The effect of column length, area replacement ratio and surcharge load on foundation settlement was investigated. The column length was varied from 40 cm to 100 cm while the area replacement ratio was changed from 0.023 to 0.093. Test results show that the foundation settlement will decrease with the increase of column length when area replacement ratio and surcharge load are certain. There is a trend of increased settlement difference between foundation with longer column and shorter column as the increase of surcharge load. For the same column length, smaller foundation settlement will be generated by bigger area replacement ratio. [ABSTRACT FROM AUTHOR]

This paper outlines the results of an experimental program carried out on centrifuge models of cantilevered and propped retaining walls embedded in saturated sand. The main aim of the paper is to investigate the dynamic response of these structures when the foundation soil is saturated by measuring the accelerations and pore pressures in the soil, displacements and bending moment of the walls. A comparison among tests with different geometrical configurations and relative density of the soil is presented. The centrifuge models were subjected to dynamic loading in the form of sinusoidal accelerations applied at the base of the models. This paper also presents data from pressure sensors used to measure total earth pressure on the walls. Furthermore, these results are compared with previous dynamic centrifuge tests on flexible retaining walls in dry sand. [ABSTRACT FROM AUTHOR]

Many studies were conducted on the modelling of stress distribution of soil foundations based on the elastic theory or uniformly spread hypothesis, but few works focused on the modelling of dynamic stress distribution in railway substructures. In this study, field monitoring was performed at Vierzon, France, using two embedded stress sensors. Dynamic stress data were recorded during train passages at different speeds, from 60 km/h to 200 km/h. Note that the Vierzon site involves a conventional line that is characterised by the presence of an interlayer soil, sandwiched between the ballast layer and the subgrade. The recorded data was firstly used to verify the existing models currently used in practice, revealing the advantages and drawbacks of such models. Then, based on the theory of stochastic stress diffusion in particulate media, a modified load spread model was developed. Comparison with the recorded data shows the relevance of the proposed model. In particular, significant effect of modulus ratio bewteen two adjacent layers on stress distribution was evidenced. [ABSTRACT FROM AUTHOR]

There is a historic lack of research examining inner soil plugging and outer lateral soil deformation during installation of pipe piles in clay. Furthermore, the influence of the pile tip geometry on soil deformation has not been investigated. Cast-in-place concrete pipe (PCC) piles are a recent generation of pipe piles for soft ground improvement applications, and are cast in place using an innovative double-walled steel casing with a tapered tip. This paper investigates the effect of tip geometry on soil flow mechanisms inside and outside the PCC pile casing during installation in clay. Large-deformation finite element (LDFE) analysis was conducted simulating the continuous penetration process of the casing installation. The LDFE results were validated against ( i) field monitoring data in terms of soil lateral displacement and heave outside the casing and ( ii) centrifuge test data in terms of penetration resistance, with excellent agreement obtained. An extensive parametric study was then performed encompassing a practical range of parameters. The geometry of the casing tip was shown to have significant influence on the soil movements inside and outside the casing, but minimal effect on the casing penetration resistance. The optimal tapered tip with a tip angle of 45° and minimal extended tip length beneath the tip angle allowed more soil to be pushed inside the casing and less lateral displacement outside the casing, which dictates the amount of concrete required to fill the cavity inside the pile and the pile construction sequence, respectively. Design expressions are proposed for estimating soil movements inside and outside the casing with optimal tip geometry being installed. [ABSTRACT FROM AUTHOR]

Current foundation design practice for serviceability limit states involves proportioning the foundation to achieve an acceptably small probability that the foundation settlement exceeds some target maximum total settlement. However, it is usually differential settlement that leads to problems in the supported structure. The design question, then, is how should the target maximum total settlement of an individual foundation be selected so that differential settlement is not excessive? Evidently, if the target maximum total settlement is increased, the differential settlement between foundations will also tend to increase, so that there is a relationship between the two, although not necessarily a simple one. This paper investigates how the target maximum total settlement specified in the design of an individual foundation relates to the distribution of the differential settlement between two identical foundation elements, as a function of the ground statistics and the distance between the two foundations. A probabilistic theory is developed, and validated by simulation, which is used to prescribe target maximum settlements employed in the design process to avoid excessive differential settlements to some acceptable probability. [ABSTRACT FROM AUTHOR]

On the basis of requirements on retaining and protection of deep foundation pit in subway stations, this study analyzes deformation laws of deep soil horizontal displacement, ground settlement and axial load of bracing of foundation pit. Through changing relevant parameters of soil mass and space enclosing structure, this study also explores effect of different physical properties of soil, different types and layout forms of fashioned iron and different pre axial forces on deformation of retaining structures of soil mixing wall (SMW), as well as put forward relevant measures for predicting and controlling of foundation pit deformation. Besides, numerical modeling is also performed during excavation process of subway stations and effects of different parameters on structure of foundation pit deformation are obtained. [ABSTRACT FROM AUTHOR]