Settlement Of Shallow Foundations Research Articles

SOIL STRUCTURE INTERACTION AND STRUCTURAL RESPONSE USING DYNAMIC TEST SYSTEM

Reducing the accessibility of real building sites has contributed to an expansion in the usage of smaller areas, in which the bearing limit of the fundamental sediments is exceedingly limited. The conventional strategy would be to get a deep and exclusive base for these weak stores. There is a necessity to create real-world provisions that have made ground improvement a significant exploration area. The settlement of shallow foundations and bearing capacity as a cost-effective foundation system. The foundation beds are laid on the thin soil in low-lying, poorly-drained soil. The resulting improved granulated layer decreases the settlements by providing a better pressure distribution and strengthening the performance to bear the underlying weak soil’s load. To support shallow foundations, the use of reinforced soils has received considerable attention during the past 35 years. Various researchers have expanded knowledge of strengthened soil’s support possible benefits on bearing capacity, shallow base settlement, and failure mechanisms. Several empirical and experimental experiments have been shown to test the bearing ability of strengthened soil footings.

Effect of Strong Motion on Liquefaction-Induced Settlement of Shallow Foundations using 3D Numerical Analysis

Effect of Strong Motion on Liquefaction-Induced Settlement of Shallow Foundations using 3D Numerical Analysis

Improving Accuracy in Shallow Foundation Settlement Prediction Using Rock Engineering System Method

Improving Accuracy in Shallow Foundation Settlement Prediction Using Rock Engineering System Method

Intelligent computing hybrid models on estimating the consolidation settlement of shallow foundations

Intelligent computing hybrid models on estimating the consolidation settlement of shallow foundations

Evaluation of clay layer presence on shallow foundation settlement in dry sand under an earthquake

Abstract Seismically, settlement of buildings with shallow foundations lying above dry sand soils has caused severe destruction in recent earthquakes. This study investigated the effect of seismic loads with shallow foundations located above sandy soil containing an intermediate soft clay layer. The impact of a clay layer’s existence with different thickness and closeness to the base of foundation when subjected to El Centro earthquake with 6.9 magnitude. This investigation has been carried out with the help of a three-dimensional PLAXIS 3D, which has been used to solve many geotechnical issues. A database was created for the various dynamic and static parameters of soils in seismically active areas of Iran and Iraq and USA. In this research, important factors are recognized, including relative density. Clay layer thickness and proximity to the foundation, the soil relative density the results of this research indicated that shallow foundation settlement increased on the dry sand and decreased with the presence of clay layer thickness and wave propagation in cohesion soil is less than cohesion-less soil. In addition, it was reached that as close as the clay layer to the foundation the settlement increased.

Settlement prediction of shallow foundations for quality controls of sandy hydraulic fills

This paper describes a procedure for settlement prediction of shallow foundations on carbonate sands, but it is fully applicable and valid for siliceous sands. For practical purposes, the design of shallow foundations resting on medium dense and dense granular soils is typically governed by limiting settlement to tolerable values. Predicting foundation settlement is therefore important, but in standard practice it is necessarily based on indirect (and therefore often conservative) determinations of soil compressibility (or modulus), due to the intrinsic difficulties in obtaining direct measurements.While numerical analyses incorporating non-linear soil behaviour may be a preferred method for computing expected total and differential settlement of shallow foundations of given geometry and stiffness on sand under static loading, the method described in this paper consists of a simplified and expeditious method based on equivalent linear elasticity. The method uses: i) the elastic soil stiffness profile at small strain, E0(z) obtained from the shear wave velocity as the primary measurement of deformability and ii) the reduction in modulus as a function of strain magnitude, E(ε) to account for stiffness non-linearity. The beneficial effect on the soil initial stiffness of the applied footing load is also considered. The method was developed as an on-site tool for checking the compaction of hydraulic fills made of carbonate sand to form artificial islands, but its application can be extended to other natural and anthropogenic coarse-grained materials.

An improved creep correction factor for footings on sand using macro-element simulations

In many settlement prediction methods, the creep settlement of shallow foundations on sand is either disregarded or accounted for using time correction factors that lack a reliable basis. These existing settlement correction factors for creep have mainly been derived from a restricted number of long-term settlement measurements and do not consider the influence of factors such as the load level, rate of load application and properties of the soil below the foundation. In this study, a newly proposed one-dimensional elasto-viscoplastic macro-element was used to investigate the factors influencing the time-dependent behaviour of shallow foundations on sand. The safety factor of the foundation, the creep characteristics of the soils and the duration of load application were found to have important effects on the post-construction settlement development. The simulation results were used to develop an enhanced settlement correction factor for creep, which takes into account the identified factors. The improved settlement correction factor was found to be comparable to existing ones when the safety factor of the foundation is 3. The effectiveness of the proposed settlement correction factor is demonstrated using creep settlement measurements from one field footing test and two case histories.

ТЕСТИРОВАНИЕ КОМПЬЮТЕРНОЙ ПРОГРАММЫ FEA ПРИ РАСЧЕТЕ ОСАДОК

The paper presents the calculation results of the settlement of massive shallow foundations, obtained by Belarusian scientists, using methods regulated by the norms of the Republic of Belarus for the design of TCP 45-5.01-67-2007 "Slab foundations", TCP 45-5.01-254-2012 " Footings and Foundations" and the Technical Code Eurocode 7 (Part 1,2) "Geotechnical design". The paper also demonstrates the calculation results of the settlement in a real structure - an apartment building located at 37a Stroiteley Str. in Perm, made in the program shells of Plaxis 2D Foundation 1.1, Plaxis 3D Foundation 1.1 and PC LIRA-CAD 2013 R3. The values of these settlements are compared with the corresponding results obtained in the FEA computer program. It turned out that the compared settlements coincide with a degree of accuracy sufficient for engineering calculations. The exception is the results obtained using the PC LIRA-CAD 2013 R3, which appeared to be significantly less. Finally, it is concluded that the FEA computer program can be recommended for making calculations of the slab foundation settlements, both taking into account and without taking into account the rigidity of the above-foundation structure.

Prediction of shallow foundation settlement: usage of hybridized support vector regression model

Prediction of shallow foundation settlement: usage of hybridized support vector regression model

A hybrid estimation procedure for modeling shallow foundation’s settlement: RBF-optimized neural network

The complexity of the cohesive soil structure necessitates settlement modeling beneath shallow foundations. The goal of this research is to use recently discovered machine learning techniques called the hybridized radial basis function neural network (RBFNN) with sine cosine algorithm (SCA) and firefly algorithm (FFA) to detect settlement (Sm) of shallow foundations. The purpose of using optimization methods was to find the optimal value for the primary attributes of the model under investigation. With R2 values of at least 0.9422 for the learning series and 0.9271 for the assessment series, both the produced SCA - RBFNN and FFA - RBFNN correctly replicated the Sm, which indicates a considerable degree of efficacy and even a reasonable match between reported and modeled Sm. In comparison to FFA - RBFNN and ANFIS - PSO, the SCA - RBFNN is believed to be the more correct method, with the values of R2, RMSE and MAE was 0.9422, 7.2255 mm and 5.1257 mm, which is superior than ANFIS - PSO and FFA - RBFNN. The SCA - RBFNN could surpass FFA one by 25% for the learning component and 14.2% for the test data, according to the values of PI index. Ultimately, it is apparent that the RBFNN combined with SCA could score higher than the FFA and even the ANFIS - PSO, which is the proposed system in the Sm forecasting model, after assessing the reliability and considering the assumptions.

Application of ensemble learning in predicting shallow foundation settlement in cohesionless soil

ABSTRACT Due to significant uncertainties associated with soil, it is challenging to anticipate settlement accurately for shallow footings on cohesionless soil. To produce more precise predictive settlement models, four ensemble learning models have been created in this study: Bagging, Random Forest (RF), Adaptive Boosting (AdaBoost), and Extreme Gradient Boosting (XGBoost). The models are created utilizing a sizable database based on standard penetration tests (SPT). A variety of evaluation criteria, including R 2, RMSE, and MAE, were employed to rate the performance of the models. The analysis results showed that Bagging and XGBoost models demonstrate excellent performance with R 2 values of 0.901 and 0.915, respectively, surpassing other models studied here as well as other models from the literature. Consequently, Bagging and XGBoost can be effective methods for predicting settlement in shallow foundations on cohesionless soil.

Seismic Characteristics of a Geotextile Tube-Reinforced Embankment and Shallow Foundations Laid on Liquefiable Soil

The ground in Saemangeum has a high water level and is mostly composed of silty soil and sand, which makes it susceptible to liquefaction and seepage effects. To investigate the seismic response of a geotextile tube-reinforced embankment and shallow foundations laid on a liquefiable soil, a simple spring type shaking table apparatus was developed. The variation in the response acceleration and shear stress-strain relationship were investigated, and the effect of soil improvement and reinforcement were explored, wherein one of the shallow foundations was laid on a coarse sand layer and reinforced by a polyester geotextile. The results showed that the main cause of damage to the embankment was seepage-induced liquefaction. Excessive surface accelerations were observed in the embankment soil due to lateral spreading, indicating the importance of analyzing the liquefaction potential of soils not only at the site area but also near embankments. Lastly, the inclusion of geotextile reinforcement and soil improvement only resulted in the slight reduction of shallow foundation settlement.

Numerical Modelling of Shallow Foundation on Multi-Layer Soil with varying Stiffness

The load-deformation observation under the footing is essential for foundation design. Either experimental methods or numerical modelling generally determines this phenomenon in engineering practices. This study determined the settlement of shallow foundations on Multi-layer soil profile numerically. The settlement behavior was investigated through numerical modelling with Plaxis 2D. This study site was Jamshoro region, located in province Sindh, Pakistan. From the geotechnical investigation, the soil of Jamshoro region consists of a combination of different soils, mainly shale and limestone. This type of soil shows common challenges for the serviceable and sustainable design and construction of structural foundations. The standard penetration test conducted accompanied by other geotechnical tests on shale and limestone to determine the input parameters for the model and observe the soil profile. The Mohr-Coloumb model used for shale and linear elastic for limestone. The settlement of the foundation is attended by varying the limestone layer’s depth. In this research, the settlement reduced under the footing by increasing the thickness of the limestone layer. The study observed that stiffness of lower layer significantly reduces the settlement of shallow foundation. Therefore, the effect of lower layer should be considered for the designing of foundation on multi-layered soil.

Effect of structural inertia on liquefaction-induced settlements of shallow foundations

The majority of published research on the performance-based design of shallow foundations on liquefiable soil focuses on seismic settlement accumulation by neglecting soil-structure-interaction (SSI) effects. On the other hand, SSI effects prove dominant when the foundation soil is non-liquefiable. Thus, the aim of this paper is to investigate the dynamic response of structure-foundation-soil (SFS) systems by examining the role of structural inertia on the performance of shallow foundations on liquefied soil, through a series of 3D fully coupled nonlinear numerical analyses of SFS systems. As a first step, the nonlinear fundamental period of vibration of the SFS system is correlated to the key system and excitation parameters. Next, in order to isolate the effects of structural inertia, shear-induced seismic settlements of SFS systems in liquefied soil are compared with the respective settlements of conjugate foundation-soil (FS) systems that apply the same static contact pressure on the foundation soil. Finally, approximate relations are proposed for the effects of structural inertia on liquefaction-induced settlements of shallow foundations, based on a multivariable statistical analysis of the numerous parametric numerical estimates.

Bearing capacity of strip footings on jointed rock mass

Rock masses are non-homogenous, discontinuous media composed of rock material and naturally occurring discontinuities such as joints, fractures and bedding planes. Due to the presence of the geological discontinuities such as joints, faults and bedding planes, the compressive strength and modulus of elasticity of jointed rock mass are significantly reduced and the measurement of the strength behaviour of these jointed rock masses below the foundation becomes a challenging task. Previous researches have dealt with the bearing capacity of strip footings on the jointed rock mass for concentric, eccentric, inclined loading, separately. But, very limited work has been carried out for determining the bearing capacity of footings on jointed rock mass under eccentric-inclined loading together. In this study, the behaviour of rock masses under the pressure of strip footing has been investigated. To make the problem, more realistic, eccentric-inclined load was applied on the strip footing resting on horizontal jointed rock mass. A parametric study has also been carried out to develop some non-dimensional correlation between different parameters including GSI, e/B ratio, inclination, bearing capacity, etc. Three-dimensional analysis has been carried out by the finite element method using PLAXIS 3D software. Modified Hoek–Brown criteria was used to simulate the behaviour of rock mass and elastic behaviour of foundation was taken into the consideration for analysis. From the results, it can be concluded that the bearing capacity values drop as the eccentricity of the load increases. This indicates that as the eccentricity of the load increases, the bearing capacity of jointed rock mass diminishes. The bearing capacity value decreases with increasing loading inclination with respect to vertical. In the current study, non-dimensional correlations have been developed using data from non-linear elasto-plastic FEA to forecast footing’ bearing capacity, settlement and tilt of shallow foundation. These connections rely on the inclination of the load as well as the eccentricity to breadth ratio. The results obtained from the non-dimensional correlations holds goods on comparing the results obtained from the FEM analysis.

Modification of Schmertmann-Hartman-Brown method to estimate immediate (elastic) settlement of shallow foundations

One of the methods intensively employed in many practical projects to estimate the immediate (elastic) settlement of shallow foundations is the Schmertmann-Hartman-Brown method (1978). In the method, two approaches are given as a function of type of the shallow foundation either a square/circular (axisymmetric condition) or a strip (plain strain condition) foundation. Thus, two sets of equations are provided to estimate the settlements for these types of shallow foundations. If a shallow foundation has a shape of rectangular, some approximations are suggested in the technical literature to estimate the elastic settlement of rectangular based shallow foundations. These approximations are tedious and time consuming. In this study, the Schmertmann – Hartman – Brown method (1978) is modified and only one set of equations used for any type (square, circular, rectangular, and strip) of shallow foundations is introduced. The modified method estimates the immediate settlement as precise as the original form of the method that is more complicated. Also, some hypothetical cases are considered to figure out the effect of width and length/width ratios of foundations on elastic settlement.

Prediction of Gypseous Soil Settlement Using Artificial Neural Network (ANN)

Gypseous soil exhibits problematic geotechnical engineering properties as they expand, collapse, disperse, undergo excessive settlement, owns a distinct lack of strength, and it is soluble. Gypseous soil has a metastable structure, with dissolvable minerals with a minimal quantity of clay binding the particles together. When gypseous soil unsaturated, they are quite potent. When they are subjected to increased wetness, however, the excess water weakens or damages the bonds, resulting in shear failure and subsequent settlement. Estimating the settlement of shallow foundations on gypseous soils is a difficult topic that is still not fully understood. It is concluded that artificial neural network (ANN) is appeared to be viable solution since it has been successfully used in numerous prognosis applications in geotechnical engineering. In this research, the precipitation values of gypsum soil were predicted under the influence of the applied load using an artificial neural network. The study found that this model is very good in predicting precipitation and found a convergence between the real values and the predict values.

SSI effects on seismic settlements of shallow foundations on sand

The gradual extension of performance-based design in geotechnical engineering has focused the attention on the seismic performance of foundations, typically, in terms of settlement, tilt and bearing capacity degradation. The aim of the present paper is to explore the role of superstructure inertia on the performance of shallow foundations through a series of non-linear numerical analyses of structure-foundation-soil systems, performed with the Finite Difference Code FLAC3D. The NTUA-Sand constitutive model is used to simulate the nonlinear cyclic soil response. The parametric analyses focus upon the effect of key soil-structure interaction parameters, such as the frequency characteristics of the structure – foundation (SFS) system and that of the free-field soil profile, as well as, the structural and excitation properties. Initially, the nonlinear fundamental period of vibration of the SFS system is correlated to the above key parameters of the system and the seismic excitation. In the sequel, to isolate the SSI effects, settlements of SFS systems are compared with the respective settlements of equivalent foundation-soil systems (FS). Simplified relations are finally developed for the analytical calculation of SSI effects on foundation settlements, based on a multi-variable statistical analysis of the available numerical predictions.

Numerical Modelling Observations of Settlement for Pad Footings Supported on Soft Clay Soil

Settlement calculation is an important part in the design of shallow foundations resting on soft soils. The size of the foundation, the depth of the footings, and the rise in ground water level are thought to influence settlement and have been the subject of much research for many years. Thus, this study compared several pad footing sizes using numerical techniques as the basis. The first objective of this study was to analyse soil and pad footing settlement, and to determine the optimal size of footing that withstands excessive settlement due to variation in the water table and the depth of the foundation. Three footing embedment depths of 1.5, 2, and 3m with three water table positions, at the GL (0m), 1.5, and 3m with an applied foundation concentrated load of 440 kN using five footing models of 1.5mx1.5m, 2mx1.5m, 2 m x 2 m, 2.5x1.5m, and 2.5x1.5m pad footing with a uniform thickness of 0.5m were considered. In this study, a 3D Plaxis simulation is used for predicting the settlement of shallow foundations on soft clay soils. Settlement results were discovered at various water table positions and foundation depths. The study found that the 2.5x2m footing was deemed the best among the simulated foundations, and the 3m foundation embedment was considered the best at shallow depths due to less excessive settlement than the other tested foundations. The settlement had a significant impact on the size of the foundation and the depth of the footing. The depth of the water table has a small impact on the settlement. Parametric analysis is also being used to gain a better understanding of the behaviour of the elastic settlement of various shallow foundations. It is found that the footing area increases, settlement decreases and vice versa.

Experiments and modelling of horizontal loading tests on small-scale foundations in sand

The accurate prediction of settlements of shallow foundations under operational conditions is still an open issue for both scientists and engineers, in particular in the case of complex loading conditions (e.g. combined vertical and horizontal loads). The complexity of the soil mechanical response and the difficulty in managing a multiscale problem (ranging from the local scale of the soil representative elementary volume to the macro-scale of the structure) makes a rigorous modelling of such problems particularly demanding for standard numerical tools such as three-dimensional finite-element codes. In this perspective, the well-known macroelement approach may represent a valid simplified approach, capable of overcoming these limitations and allowing a comprehensive description of both serviceability limit state and ultimate limit state of such systems, particularly useful even for practitioners. In the paper, based on a small-scale 1g experimental campaign on a strip foundation, the effect of embedment is investigated over horizontal loading paths at a constant vertical load. In particular, relatively low vertical stress values are considered for the foundations, as it often happens in real structures under usual working conditions. A simple macroelement plastic model, based on a strain hardening law with non-associated flow rule is then proposed and validated over the available experimental data.