摘要:

AbstractA simple and inexpensive laboratory device has been developed and used to simulate the behaviour of a dry underclay beam as the floor of an underground roadway subjected to a uniformly distributed uplift pressure. The Airy stress function method proved to be a useful means of expressing and predicting of the uplift of such beams. This method has been related to both classical beam theory and laboratory investigations. It was found that the Airy stress function method, utilizing polynomial equations, provides a closer fit to the mechanism of beam deformation and stress developments under dry laboratory conditions.

ISSN:0363-9061    

DOI:10.1002/nag.1610130202

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper presents a general method of key block analysis for cylindrical surfaces with numerous real or statistically produced joint traces. General tunnel curves, analytically represented, are unrolled to yield a ‘developed view’ on which the joint traces are continuous curves. Then, using extended block theory, the maximum key block regions are delimited from the curved polygons of the unrolled joint trace map. The methods discussed here apply to a cylindrical tunnel of any shape in section and in any orientation, including inclined tunnels and shafts. The trace maps for which the method applies can be generated statistically, as described herein, or surveyed from real traces on exposed tunnel walls. A brief introduction to the basic theory about tunnel key blocks is provided here so that this paper can be understood without reference to other papers on block the

ISSN:0363-9061    

DOI:10.1002/nag.1610130203

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe problem of the axial loading of a rigid disk‐shaped anchor plate embedded in an isotropic elastic medium of infinite extent is examined. At the boundary of the disk anchor plate the elastic medium contains a cracked region of finite extent. The presence of the cracked region decreases the elastic stiffness of the anchor plate. The mathematical formulation of the problem is developed, and a numerical scheme is presented which can be used to solve the resulting coupled integral equations. The numerical technique is used to evaluate the results, which illustrate the manner in which the elastic stiffness of the anchor plate is influenced by the extent of cracking. Similar results are developed for the flaw shearing mode stress intensity factor at the external boundary of the cracked regio

ISSN:0363-9061    

DOI:10.1002/nag.1610130204

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAn elastoplastic constitutive model for concrete subjected to cyclic loading conditions is presented. The model is an extension of a recently proposed constitutive concept.7An initial active loading process is described, using the conventional framework of the rate independent theory of plasticity. An appropriate hardening/softening parameter is introduced which allows one to model the sensitivity of material characteristics to varying confining pressure, including a smooth transition from stable to unstable response. For stress histories that include stress reversals, the formulation invokes a set of neutral loading loci defining the conditions of the neutral state.8The field of hardening moduli is specified through an appropriate interpolation rule which enables one to simulate adequately the effect of cyclic degradation of the material. The performance of the model is verified for some typical cyclic loading histories, and the results are compared with existing experimental data.

ISSN:0363-9061    

DOI:10.1002/nag.1610130205

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThis paper is a continuation of a previous one on bifurcation of deep boreholes under uniform stress at infinity,1and it focuses on the effect of borehole radius on borehole stability. Rock is described by the equations of a deformation theory of plasticity for cohesive‐frictional, incompressible materials with Cosserat structure. The inhomogeneous bifurcation problem is formulated and the corresponding eigenvalue problem is solved numerically by the finite element method. It is demonstrated that the combined Cosserat and stress‐gradient effects lead to an increase of the bifurcation stress with decreasing borehole radius (scale effe

ISSN:0363-9061    

DOI:10.1002/nag.1610130206

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAn understanding of the fracture mechanics of geomaterials is important for the solution of many problems in geomechanics. One of the most important material properties involved in fracture mechanics is the fracture toughness,KIc. The short‐rod test configuration proposed by Barker1has significant potential for becoming a standard test for fracture toughness determination in geomechanics. The purpose of this brief is to examine the application potential of the short‐rod test for geomechanics probl

ISSN:0363-9061    

DOI:10.1002/nag.1610130207

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractResults obtained with the finite element method are greatly affected by the overall dimensions of the mesh and the number and size of the elements used. Proper choice of the boundary conditions is also necessary to obtain an accurate estimate of the unknowns of the problem. This paper discusses some factors that influence the results of a finite element idealization of the problem of earth pressure behind a gravity wall with a dry, cohesionless backfill.

ISSN:0363-9061    

DOI:10.1002/nag.1610130208

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe coupled diffusion and deformation phenomena induced by the opening of a hydraulic fracture in a poroelastic medium are modelled using an extension of the displacement discontinuity method. This method consists in distributing fluid source and poroelastic displacement discontinuity singularities along the locus of the fracture, and over time. As an illustration, the problem of a suddenly pressurized crack in an infinite formation is examined.

ISSN:0363-9061    

DOI:10.1002/nag.1610130209

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610130210

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610130201

出版商:John Wiley&Sons, Ltd    

年代:1989

数据来源: WILEY