摘要:

AbstractThe discrete element method (DEM) models granular materials numerically as a collection of particles rather than as a continuum. Difficulties can arise when using the more common circular and polygonal shapes for modelling real granular materials. In particular, use of discs and spheres leads to typically low aggregate internal friction angles compared with real materials. This paper presents the detailed formulations for using the ellipse shape in discrete element modelling. Robust algorithms for computing ellipse‐ellipse and ellipse‐wall intersections are presented. Also shown are equations to assist in parameter selection and evaluation of macroscopic stresses and strains from the contact data. An initial validation test suite on rods of varying particle aspect ratio are presented. These results indicate that the ellipse‐based DEM results in mechanical behaviour that is similar, both qualitatively and quantitavely, to the behaviour of real

ISSN:0363-9061    

DOI:10.1002/nag.1610170902

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSettlement of the surrounding soil due to surcharge placement may give rise to negative skin friction developed in piles. In this paper, a simple discrete element approach using subgrade reaction method is proposed to analyse negative skin friction on single piles. The pile is embedded in a two‐layer soil where the upper soil layer undergoes consolidation while the lower soil layer acts as a stiffer bearing stratum. Two different and uncoupled deformation modes, one at the pile shaft and the other at the pile toe have been assumed in the determination of the soil stiffness. The effects of a compressible bearing stratum and embedment length of the pile in the bearing stratum are considered in the analysis. This simple approach is verified by comparison with rigorous methods of modelling the soil as an elastic continuum. Three reported case histories are analysed and the computed results are shown to be in reasonable agreement with the field measurement

ISSN:0363-9061    

DOI:10.1002/nag.1610170903

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe finite element method was used to solve the problem of flow to a partially penetrating strainer well in a leaky confined aquifer under steady and unsteady conditions. Predictions of the model were compared with reported pumping test data. A good agreement was obtained between them. The effects of penetration and screen position on discharge through imperfect well were studied. Results were compared with analytical solutions and presented graphically.

ISSN:0363-9061    

DOI:10.1002/nag.1610170904

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractWe present solutions for the effective stress induced by gas flow through a porous solid into a borehole resulting from sudden pressure reduction. Tensile effective stress that exceeds the strength of the solid will lead to borehole failure. This has applications to the intentional creation of cavities, relevant to the efficient recovery of coalbed methane, and the avoidance of borehole stability problems in conventional gas production.

ISSN:0363-9061    

DOI:10.1002/nag.1610170905

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610170906

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610170907

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610170901

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY