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1.
Support vector machine applied to settlement of shallow foundations on cohesionless soils 总被引：4，自引：0，他引：4
The determination of settlement of shallow foundations on cohesionless soil is an important task in geotechnical engineering. Available methods for the determination of settlement are not reliable. In this study, the support vector machine (SVM), a novel type of learning algorithm based on statistical theory, has been used to predict the settlement of shallow foundations on cohesionless soil. SVM uses a regression technique by introducing an ε – insensitive loss function. A thorough sensitive analysis has been made to ascertain which parameters are having maximum influence on settlement. The study shows that SVM has the potential to be a useful and practical tool for prediction of settlement of shallow foundation on cohesionless soil. 相似文献
2.
The settlement of shallow foundation on cohesionless soil is a key parameter in the design of shallow foundation. The recently introduced relevance vector machine (RVM) technique is applied to predict the settlement of shallow foundation on cohesionless soils. RVM allows computation of the prediction intervals, taking into account the uncertainties of both the parameters and the data. It provides much sparser regressors without compromising performance, and kernel bases give a small but worthwhile improvement in performance. It also estimates the prediction variance. This study shows that compared to the available methods, RVM is better at determining the settlement of shallow foundation on cohesionless soil. 相似文献
3.
In this paper, given an estimate of the bearing capacity of the soil, by treating settlement at a given load as a random variable and the evolution of settlement of footing on cohesionless soil with the increasing load as a stochastic process, a tri-level homogeneous Markov chain (TLHMC) model is proposed for prediction of settlement. Comparison of the predicted mean and bounds on settlements, obtained using TLHMC, with the respective field values obtained from literature shows that the stochastic evolution can be modelled using TLHMC with a correlation coefficient of 0.90. A methodology for reliability-based design of footings is also presented and its use is demonstrated through a numerical example. 相似文献
4.
This paper examines the potential of least‐square support vector machine (LSVVM) in the prediction of settlement of shallow foundation on cohesionless soil. In LSSVM, Vapnik's ε‐insensitive loss function has been replaced by a cost function that corresponds to a form of ridge regression. The LSSVM involves equality instead of inequality constraints and works with a least‐squares cost function. The five input variables used for the LSSVM for the prediction of settlement are footing width (B), footing length (L), footing net applied pressure (P), average standard penetration test value (N) and footing embedment depth (d). Comparison between LSSVM and some of the traditional interpretation methods are also presented. LSSVM has been used to compute error bar. The results presented in this paper clearly highlight that the LSSVM is a robust tool for prediction of settlement of shallow foundation on cohesionless soil. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
5.
This article focuses on the statistical characterisation and stochastic modelling of the load-displacement behaviour of shallow footings on cohesionless soils and on the probabilistic estimation of settlement for serviceability limit state design (LSD). The study relies on a field database of 30 full-scale footings subjected to vertical loading with cone penetration testing data available for each site. The performance of three load-displacement models in replicating field data is assessed comparatively through statistical analysis. Load-displacement uncertainty is subsequently modelled probabilistically to perform Monte Carlo Simulation (MCS)-based estimation of footing settlement using the best-performing power law model. The dependence among load-displacement model parameters is investigated and replicated using copula theory. Samples are generated to account for parametric uncertainties in model inputs. The simulation output samples of settlement are examined statistically in order to assess the relevance of parametric and load-displacement uncertainties in settlement estimation, as well as the importance of accounting for correlation between power law model parameters. A simple analytical model for the estimation of settlement at any target reliability level is obtained on the basis of the outputs of MCS. The model can be practically implemented in geotechnical LSD at serviceability limit states. 相似文献
6.
《Geomechanics and Geoengineering》2013,8(2):139-150
The influence of a non-coaxial model for granular soils on shallow foundation analyses is investigated. The non-coaxial plasticity theory proposed by Rudnicki and Rice (J. Mech. Phys. Solids 1975, 23, 371–394) is integrated into a Drucker–Prager model with both perfect plasticity and strain hardening. This non-coaxial model is numerically implemented into the finite-element program ABAQUS using a substepping scheme with automatic error control. The influence of the non-coaxial model on footing settlement and bearing capacity is investigated under various loading and boundary conditions. Compared with the predictions using conventional coaxial models, the non-coaxial prediction results indicate that the settlement of a footing increases significantly when the non-coaxial component of plastic strain rate is taken into consideration, although ultimate footing bearing capacities are not affected significantly. The non-coaxial model has a different effect on footing settlements under different loading and boundary conditions. In general, the discrepancies between coaxial and non-coaxial predictions increase with increasing rotation of principal stresses of the soil mass beneath a footing. It can be concluded that if the non-coaxial component of plastic strain rate is neglected in shallow foundation problems using the finite-element method, the results tend to be non-conservative when designs are dominated by settlement of footings. 相似文献
7.
Pijush Samui 《国际地质力学数值与分析法杂志》2012,36(1):100-110
This study employs two statistical learning algorithms (Support Vector Machine (SVM) and Relevance Vector Machine (RVM)) for the determination of ultimate bearing capacity (qu) of shallow foundation on cohesionless soil. SVM is firmly based on the theory of statistical learning, uses regression technique by introducing varepsilon‐insensitive loss function. RVM is based on a Bayesian formulation of a linear model with an appropriate prior that results in a sparse representation. It also gives variance of predicted data. The inputs of models are width of footing (B), depth of footing (D), footing geometry (L/B), unit weight of sand (γ) and angle of shearing resistance (?). Equations have been developed for the determination of qu of shallow foundation on cohesionless soil based on the SVM and RVM models. Sensitivity analysis has also been carried out to determine the effect of each input parameter. This study shows that the developed SVM and RVM are robust models for the prediction of qu of shallow foundation on cohesionless soil. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
8.
Maher Omar Khaled Hamad Mey Al Suwaidi Abdallah Shanableh 《Arabian Journal of Geosciences》2018,11(16):464
This research proposes the use of artificial neural network to predict the allowable bearing capacity and elastic settlement of shallow foundation on granular soils in Sharjah, United Arab Emirates. Data obtained from existing soil reports of 600 boreholes were used to train and validate the model. Three parameters (footing width, effective unit weight, and SPT blow count) are considered to have the most significant impact on the magnitude of allowable bearing capacity and elastic settlement of shallow foundations, and thus were used as the model inputs. Throughout the study, depth of footing was limited to 1.5 m below existing ground level and water table depth taken at the level of the footing. Performance comparison of the developed models (in terms of coefficient of determination, root mean square error, and mean absolute error) revealed that the developed artificial neural network models could be effectively used for predicting the allowable bearing capacity and elastic settlement. As such, the developed models can be used at the preliminary stage of estimating the allowable bearing capacity and settlements of shallow foundations on granular soils, instead of the conventional methods. 相似文献
9.
In recent times, rapid urbanisation coupled with scarcity of land forces several structures to come up ever closer to each
other, which may sometime cause severe damage to the structures from both strength and serviceability point of view, and therefore,
a need is felt to devise simplified methods to capture the effect of footing interference. In the present study, an attempt
has been made to model the settlement behaviour of two strip footings placed in close spacing on layered soil deposit consisting
of a strong top layer underlying a weak bottom layer. Theory of elasticity is employed to derive the governing differential
equations and subsequently solved by the finite difference method. The perfectly rough strip footings are considered to be
resting on the surface of two-layer soil system, and the soil is assumed to behave as linear elastic material under a range
of static foundation load. The effect of various parameters such as the elastic moduli and thickness of two layers, clear
spacing between the footings and footing load on the settlement behaviour of closely spaced footings has been determined.
The variation of vertical normal stress at the interface of two different soil layers as well as at the base of the failure
domain also forms an important part of this study. The results are presented in terms of settlement ratio (ξδ), and their variation is obtained with the change in clear spacing between two footings. The present theoretical investigation
indicates that the settlement of closely spaced footings is found to be higher than that of single isolated footing, which
further reduces with increase in the spacing between the footings. 相似文献
10.
Hamed Gholami Ehsan Seyedi Hosseininia 《Geotechnical and Geological Engineering》2017,35(5):2137-2146
Ring footings can be more effective and economical than circular footings. In spite of similarities between circular and ring footings, their behaviors are different in some respects such as bearing pressure distribution under the footing and settlement. But no exclusive theoretical prediction of ultimate bearing capacity has been reported for ring footings. In the present study, stress characteristics method is employed for coding the bearing capacity of ring footing with horizontal ground surface. In the calculations, friction at the contact between the soil and foundation is considered. In this research, the soil obeys the Mohr–Coulomb yield criterion and that is cohesive–frictional-weighted with applied surcharge pressure. The bearing capacity factors Nγ, Nq and Nc for ring footings were calculated by a written code based on the method of characteristics. Bearing capacity was determined for different conditions of soil and different ratio of radii in comparison with the principle of superposition results. The findings show that the principle of superposition is effective for determining the bearing capacity of a ring footing. 相似文献
11.
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13.
A settlement analysis of a cohesionless soil layer subjected to an earthquake is presented. A theoretical solution utilizing Bessel functions and based on the so-called densification model for amplitudes has been obtained. This permits to calculate the settlement under cyclic loading. The simplified formula is also presented which allows for the fast and straightforward estimation of settlement. A numerical example is included giving the comparison of results obtained by different methods. 相似文献
14.
This paper presents a study on the bearing capacity of eccentrically-loaded rough ring footings resting over cohesionless soil. To this aim, a series of 3D numerical simulations were performed using the finite difference method. In order to consider the effect of load eccentricity, reduction factor method is applied. In this method, the ratio of an eccentrically-loaded bearing capacity to the bearing capacity of the same footing under vertical load is defined. Comparison between the results of the numerical simulations with those of analytical solutions and experimental data indicates good agreement. A mathematical expression is also introduced for eccentrically-loaded ring footings. 相似文献
15.
软土路基沉降实时建模动态预测 总被引：6，自引：2，他引：4
在路基填筑施工过程中,用多项式与时间序列AR组合模型预测其沉降变形发展。根据沉降观测值,采用统计分析方法识别和建立多项式预测模型,预测在某时期沉降趋势值;用平稳时间序列分析方法建立随机部分模型,并预测沉降随机部分值,二者之和即为某时期沉降预测值。随着新观测数据的不断加入,及时修改预测模型参数值,达到实时预测之目的。工程实例研究表明：组合模型预测值明显优于单一趋势模型预测值。组合模型一步预测误差绝对值大多数情况下小于5 mm。预测步数越多,预测误差则越大。 相似文献
16.
By using small scale model tests, the interference effect on the vertical load-deformation behavior of a number of equally
spaced strip footings, placed on the surface of dry sand, was investigated. At any stage, all the footings were assumed to
(i) carry exactly equal magnitude of load, and (ii) settle to the same extent. No tilt of the footing was permitted. The effect
of clear spacing (s) among footings on the results was explored. A new experimental setup was proposed in which only one footing
needs to be employed rather than a number of footings. The bearing capacity increases continuously with decrease in spacing
among the footings. The interference effect becomes further prominent with increase in soil friction angle. In contrast to
an increase in the bearing capacity, with decrease in spacing of footings, an increase in the footing settlement associated
with the ultimate state of shear failure was observed. The present experimental observations were similar to those predicted
by the available theory, based on the method of characteristics. As compared to the theory, the present experimental data,
however, indicates much greater effect of interference especially for larger spacing among footings. 相似文献
17.
基坑工程施工过程中的周边地面沉降直接关系到周围建筑物的安全,本文根据上海前滩地区某基坑工程的历史监测数据、施工工况和周边地层参数等多源数据对基坑周边地面沉降进行监测和预测。以PSO-BP神经网络为基础,通过将基于时序和基于沉降影响因素的网络模型对比发现：二者预测结果误差较小且基于时序的神经网络预测精度更高,说明利用PSO-BP神经网络能够很好地对基坑周边地面沉降进行分析与预测。为了综合考虑时间效应和空间效应的影响,在基于沉降影响因素的预测模型的基础上加入历史监测数据作为模型输入层进行优化,结果表明：优化后的PSO-BP神经网络模型具有更小的相对误差范围和更高的预测精度,在基坑周边地面沉降预测中有很好的应用前景。 相似文献
18.
Swami Saran Surendra Kumar K.G. Garg Arvind Kumar 《Geotechnical and Geological Engineering》2007,25(1):123-137
In the present paper, a method of analysis for calculating the pressure intensity corresponding to a given settlement for
eccentrically and obliquely loaded square and rectangular footings resting on reinforced soil foundation has been presented.
The process has been simplified by presenting non-dimensional charts for the various terms used in the analysis, which can
be directly used by practicing engineers. An approximate method has been suggested to find out the ultimate bearing capacity
of such footings on reinforced soil. The results have been validated with the model test results. The procedure has been made
clear by giving an illustrative example. 相似文献
19.
Occurrence of liquefaction in saturated sand deposits underlying foundation of structure can cause a wide range of structural damages starting from minor settlement, and ending to general failure due to loss of bearing capacity. If the bearing capacity failure is not the problem, reliable estimation of the liquefaction-induced settlement will be of prime importance in assessment of the overall performance of the structure. Currently, there are few procedures with limited application in practice for estimation of settlement of foundations on liquefied ground. Therefore, development of a general relationship is important from the practical viewpoint. In this paper, the dynamic response of shallow foundations on liquefied soils is studied using a 3D fully coupled dynamic analysis. For verification of the numerical model, simulation of a centrifuge experiment is carried out and the analysis results are compared with the experimental measurements. The results of centrifuge experiment are taken from the literature for the purpose of comparison and the experiment has not been performed by the authors. After verification of the numerical model, a practical relationship for estimation of liquefaction-induced settlement of rigid footings on homogeneous loose to medium fine sand is proposed based on the results of a comprehensive parametric study. In the interpretation process, the soil layer thickness in which the liquefaction takes place is found to be a key parameter, since by normalization with respect to this parameter, effects of a number of other parameters can be eliminated. 相似文献
20.
This paper presents a new method proposed for the prediction of long term settlement of very heavy structures based on a numerical interpretation of long term pressuremeter creep tests. The constitutive model used for the modelling of the soil creep is described. The constants of the constitutive model are determined by fitting a simulated curve, given by a simple Finite Element Method, to the results of a long term pressuremeter creep test. The calculation of long term settlement under nuclear power plants, using the soil parameters defined by this method, is presented and compared with the in situ measured values. 相似文献