Stability analysis and design charts for a sandy soil slope supporting an embedded strip footing

International Journal of Geo-Engineering, Sep 2018

In several field situations, especially in the hilly terrains, the construction of footings on slopes becomes essential. The factor of safety of a slope supporting a loaded footing on the crest is dependent on the position of the footing from the crest edge. Most studies in the past have focused on analysing the bearing capacity and settlement behaviour of a footing resting on a slope crest, but foundations in most infrastructure projects are usually built at some depth below the ground surface. Therefore, the availability of some form of design charts for determining the factor of safety of a slope supporting an embedded footing will be highly useful for the practising engineers. In the current work, the finite element analysis of a sandy soil slope supporting an embedded footing was carried out using the Plaxis 2D, a finite element-based commercial software, in order to examine the effect of slope geometry, soil properties, and footing locations on the stability of slope in terms of factor of safety. The results of the analysis show that the factor of safety of the slope increases with an increase in the footing edge distance, footing depth and soil relative density, but it decreases with an increase in the slope angle and applied pressure on the footing. Some design charts have been developed along with an illustrative example to explain how these charts can be used by the practising engineers.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://link.springer.com/content/pdf/10.1186%2Fs40703-018-0082-2.pdf

Stability analysis and design charts for a sandy soil slope supporting an embedded strip footing

International Journal of Geo-Engineering December 2018, 9:13 | Cite as Stability analysis and design charts for a sandy soil slope supporting an embedded strip footing AuthorsAuthors and affiliations Emmanuel Baah-FrempongSanjay Kumar Shukla Open Access Original Research First Online: 11 September 2018 Received: 23 April 2018 Accepted: 20 August 2018 171 Downloads Abstract In several field situations, especially in the hilly terrains, the construction of footings on slopes becomes essential. The factor of safety of a slope supporting a loaded footing on the crest is dependent on the position of the footing from the crest edge. Most studies in the past have focused on analysing the bearing capacity and settlement behaviour of a footing resting on a slope crest, but foundations in most infrastructure projects are usually built at some depth below the ground surface. Therefore, the availability of some form of design charts for determining the factor of safety of a slope supporting an embedded footing will be highly useful for the practising engineers. In the current work, the finite element analysis of a sandy soil slope supporting an embedded footing was carried out using the Plaxis 2D, a finite element-based commercial software, in order to examine the effect of slope geometry, soil properties, and footing locations on the stability of slope in terms of factor of safety. The results of the analysis show that the factor of safety of the slope increases with an increase in the footing edge distance, footing depth and soil relative density, but it decreases with an increase in the slope angle and applied pressure on the footing. Some design charts have been developed along with an illustrative example to explain how these charts can be used by the practising engineers. KeywordsFactor of safety Slope stability Strength reduction technique Failure zone  Introduction The stability analysis of slopes has been a challenging task for geotechnical engineers since ancient days. In assessing the stability of any slope, the focus is mainly on calculating the factor of safety to estimate the degree of closeness of the slope from the failure condition. Some infrastructure projects, particularly in hilly terrains, involve the construction of footings/foundations on slopes. When a foundation is built on a slope, the factor of safety is expected to reduce depending on the foundation location relative to the crest edge and its depth. In the past, several studies have been carried out on the bearing capacity and settlement behaviour of footings resting on unreinforced slopes. Some investigators have developed analytical formulations to estimate the bearing capacity of a footing positioned on a slope [1, 2, 3, 4, 5, 6]. Meyerhof [4] developed an analytical formulation to estimate the bearing capacity of a footing on a slope face and crest for both completely cohesive and cohesionless soils. For a footing on top of the slope, it was reported that the bearing capacity factors decreased with higher slope inclination and increased with the footing distance from the slope edge. The bearing capacity of the footing is independent of the slope angle when the footing is located at a distance, greater than 2–6 times the footing width, from the slope crest edge. Graham et al. [3] used the stress characteristics to analyse the load-bearing pressure of a footing on cohesionless soil slope. They compared their results with the experimental data of Shields et al. [7] and found a good agreement between them. Saran et al. [6] used the limit equilibrium and limit analysis methods to obtain the bearing capacity of a foundation close to a slope. It was demonstrated that the two methods produced almost the same results presented in the form of non-dimensional bearing capacity factors which are influenced by the soil friction angle, slope inclination and footing edge distance. Narita and Yamaguchi [5] carried out a log-spiral analysis of the bearing capacity of footings located on slopes. They compared their results with other analytical and experimental works and found that the method overestimates the bearing capacity in comparison to other analytical solutions. A good agreement was however observed between the ultimate bearing capacity and the form of failure surface from the log spiral analysis and the laboratory model test. Buhan and Garnier [1] analysed the load bearing behaviour of a footing close to a slope by the yield design theory and compared the predictions with a full scale and a centrifuge test results. Castelli and Motta [2] utilised the limit equilibrium method to investigate the load bearing capacity of a foundation on a ground surface with a slope. A parametric study, under static and seismic conditions, was conducted to examine the effect of footing edge distance, slope inclination, footing embedment depth and seismic coefficients on the footing load bearing pressure. Some investigators have ana (...truncated)


This is a preview of a remote PDF: https://link.springer.com/content/pdf/10.1186%2Fs40703-018-0082-2.pdf

Emmanuel Baah-Frempong, Sanjay Kumar Shukla. Stability analysis and design charts for a sandy soil slope supporting an embedded strip footing, International Journal of Geo-Engineering, 2018, pp. 13, Volume 9, Issue 1, DOI: 10.1186/s40703-018-0082-2