Suraparb Keawsawasvong

Bio: Suraparb Keawsawasvong is an academic researcher from Thammasat University. The author has contributed to research in topics: Geotechnical engineering & Bearing capacity. The author has an hindex of 21, co-authored 93 publications receiving 970 citations. Previous affiliations of Suraparb Keawsawasvong include Chulalongkorn University.

Three-dimensional undrained tunnel face stability in clay with a linearly increasing shear strength with depth

Abstract: The undrained tunnel face stability in clay with a linearly increasing shear strength with depth was investigated by three-dimensional finite element analysis. Three parametric studies were performed to study the effects of the cover depth ratio, overburden stress factor and linear strength gradient ratio on the load factor of the undrained tunnel face stability. The influence of the linear strength gradient ratio on the predicted failure mechanism of the undrained face stability was discussed and examined. An approximate closed-form solution was proposed for three-dimensional undrained tunnel face stability in clays with constant or linearly increasing shear strength profiles with depth.

Undrained Stability of Unlined Square Tunnels in Clays with Linearly Increasing Anisotropic Shear Strength

Abstract: In general, the undrained strength anisotropy of clays is found in nature. Its effect on a stability problem during undrained loading should be considered in order to get a more accurate and realistic safety assessment. In this paper, the undrained stability of unlined square tunnels in anisotropic and non-homogeneous clays is investigated by the lower bound finite element limit analysis using second-order cone programming. The anisotropic undrained strength of clays is modelled by using an elliptical strength envelope under plane strain conditions. The stability analyses of the problem are performed by the comprehensive investigations of the effects of the cover-depth ratio, the normalized overburden pressure, the normalized strength gradient, and the anisotropic strength ratio on the stability load factor and associated failure mechanisms. The computed lower bound solutions are validated with the existing results of square tunnels in isotropic clays. The new approximate equations of the stability load factor and factor of safety for square tunnels in anisotropic and non-homogeneous clays are first time presented by using a nonlinear regression, hence providing a reliable, accurate and convenient tool for stability analyses of the problem in practice. The numerical results reveal that the strength anisotropy has a significant impact on the stability load factor, especially when anisotropic clays have much difference in undrained strengths between compression and extension.

Stability of unlined square tunnels in Hoek-Brown rock masses based on lower bound analysis

Abstract: In this paper, the lower bound (LB) finite element limit analysis in conjunction with semidefinite programming (SDP) is developed and employed to investigate the stability of unlined square tunnels in Hoek-Brown (HB) material. Extensive parametric studies on the load factor of unlined square tunnels are conducted on practical ranges of the cover-depth ratio of tunnels, normalized uniaxial compressive strength of intact rock, geological strength index (GSI) and HB material constant (mi). The presented results are useful for a reliable and accurate assessment of the stability of unlined square tunnels in rock masses in practice.

Undrained stability of an active planar trapdoor in non-homogeneous clays with a linear increase of strength with depth

Abstract: Finite element limit analysis was employed to determine the upper and lower bound solutions of the active failure of a planar trapdoor in non-homogeneous clays that have a linear increase of strength with depth. Influences of cover ratio, dimensionless strength gradient and trapdoor roughness on predicted failure mechanisms and stability factors were determined. In all cases, the exact stability factors were accurately bracketed by computed bound solutions within 1%. Accurate closed-form equations to predict the exact estimates of stability factors, trapdoor pressure and factor of safety using the new proposed factors for the cohesion and strength gradient are presented.

Pile Foundation Analysis And Design

Abstract: Thank you very much for downloading pile foundation analysis and design. Maybe you have knowledge that, people have search numerous times for their favorite novels like this pile foundation analysis and design, but end up in infectious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they juggled with some malicious bugs inside their laptop. pile foundation analysis and design is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library spans in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the pile foundation analysis and design is universally compatible with any devices to read.

P-ultimate for undrained analysis of laterally loaded piles. discussion and closure

Abstract: A discussion of a paper with the aforementioned title by Murff and Hamilton, published in this journal (Volume 119, Number 1, January 1993), is presented The discussion focuses on laterally loaded piles in layered soils Maugeri, Castelli, and Motta assert that the authors' method overpredicts the ultimate lateral resistance on the pile Discussion is followed by closure from the authors

Stability of strutted excavations in clay

Abstract: L'article suivant donne une description de la methode theorique pour le calcul du danger d'un soulevement du fond d'une fouille cadragee dans l'argile. Terzaghi et Tschebotarioff ont deja donne des formules pour un pareil calcul, mais ces formules ne sont valables que pour des fouilles de petite profondeur. Basee sur les formules de la capacite portante des fondations dans l'argile, une nouvelle solution du probleme de soulevement du fond a ete developpee. La profondeur critique d'une fouille est donnee par : D c = N c . S/γ ou s et γ sont respectivement la resistance au cisaillement et le poids d'unite de l'argile, N c etant un coefficient sans dimension et dependant de la forme de la fouille, c'est-a-dire de la proportion largeur-longueur et de la proportion profondeur-largeur. Les valeurs de N c , identiques aux valeurs donnees par Skempton (1951) pour la capacite portante, sont montrees graphiquement dans la Figure 2. La validite de ces formules a ete examinee par comparaison de quatorze fouilles. Dans sept de ces fouilles, un soulevement total du fond a eu lieu, les coefficients theoriques de securite donnant comme valeur moyenne de 0,96. Quatre fouilles, ou on constatait un soulevement partiel du fond, ont fourni une valeur moyenne des coefficients theoriques de securite de 1,11. Les trois dernieres fouilles ont ete accomplies sans evenement speciaux, mais des observations sur place indiquaient que, avec une profondeur agrandissante, on aurait du craindre un soulevement du fond, la valeur moyenne des coefficients theoriques de securite etant de 1,08. Les resultats obtenus ci-dessus montrent, ainsi, que la methode decrite nous permet d'estimer avec une precision suffisante le danger d'un soulevement du fond d'une fouille dans l'argile, et que la methode suffit pour la plupart des usages pratiques.

Tunnel face stability in cohesion-frictional soils considering the soil arching effect by improved failure models

Abstract: To better assess the stability of tunnel faces in cohesion-frictional soils, tunnel face stability was investigated considering the soil arching effect in this study. An improved 3D rotational failure model based on the limit analysis method and an improved wedge-prism model based on the limit equilibrium method were proposed. Simultaneously, the lateral stress ratio K s was improved to reflect the soil arching effect. The support pressures obtained by the two proposed models were validated by the numerical results and existing works. Finally, the effects of the geometrical and geotechnical parameters and loading conditions on the tunnel face stability were assessed.

Analytical solution for longitudinal vibration of a floating pile in saturated porous media based on a fictitious saturated soil pile model

Abstract: Based on Biot’s theory of wave propagation in saturated porous media, a new analytical approach for the vertical vibration of a floating pile in saturated viscoelastic soil is proposed, by combining the differential operator method with a fictitious saturated soil pile (FSSP) model. As an extended fictitious soil pile model, the FSSP model can fully consider the wave propagation in saturated soil with limit thickness beneath pile toe. The analytical solution for the velocity admittance of pile head is derived by introducing the completely coupled conditions at the pile-soil interface. The accuracy of the proposed approach and relevant solutions are degenerated and subsequently verified via comparisons with previous solutions. In addition, comparative analyses are further carried out to examine the effects of the porosity and shear modulus of soil as well as the layer thickness of the saturated soil layer beneath pile toe on the dynamic behavior of the floating pile. It is indicated that the presented approach and relevant solutions provide a more wide-ranging application for vertical vibration problems of a floating pile in saturated soil, which can be degenerated for the vertical vibration problems of a floating pile in single-phase soil or an end-bearing pile in saturated soil.