摘要:

AbstractThe paper reviews the application of numerical methods in tunnelling, the achievements and the shortcomings, hence also the future tasks for closing the gap between real ground behaviour in critical tunnelling situations and the present approaches by numerical models. After discussing the role of the structural model within the entire design procedure for a tunnel project, problems are mentioned where numerical methods are essential. This is explained for soft ground tunnelling as well as for tunnels in rock. A special section is devoted to the kind of numerical models needed for the interpretation of field measurements. There is still much to do, especially in covering failure modes of tunnels by numerical analysis. The paper is a shorter version (e.g. without photographs of the actual tunnelling work) of a lecture presented at the Innsbruck Conference on Numerical Methods in 1988.

ISSN:0363-9061    

DOI:10.1002/nag.1610150402

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper analyses the shape effect on the tensile strength of axisymmetric rock specimens by an improved adaptive dynamic relaxation method. It is shown that the present approach is convenient and efficient. Numerical results for spheroidal specimens with different shapes reveal the variation of stress distributions along the loading axes and suggest that loading along the shorter principal axis is preferable in strength tests. Furthermore, an empirical formula based on the failure criterion of maximum tensile stress is proposed to evaluate the tensile strength of specimen materials.

ISSN:0363-9061    

DOI:10.1002/nag.1610150403

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe implications of assuming isotropic elasto–plasticity to model the behaviour of soil under simple shear conditions are considered. For small strains, use of such a model implies the following three consequences: (1) strains and strain increments at any stage of shearing may be expressed as the sum of elastic and plastic components; (2) principal directions of stress and of plastic strain increment are collinear; (3) principal directions of stress increment and of elastic strain increment are collinear. These consequences are used in order to establish relationships between the stresses, stress increments and strains which develop in a simple shear test. No additional assumptions with regards the form of the yield function, the flow rule or the hardening function are required for this development. By defining the ratio of the plastic to the total shear strain increment on the horizontal plane (the plane of zero extension) as λ, it is possible to define the horizontal normal stress σxin terms of λ and other stresses and strains which are normally known during simple shear loading. As a result, all components of the stress tensor in the simple shear plane may be defined. Results of some direct simple shear tests on soft clay have been interpreted using the model and found to be generally consistent with some of the observations reported in the literature from tests in which boundary stresses were meas

ISSN:0363-9061    

DOI:10.1002/nag.1610150404

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractAnalytical solutions for the two‐dimensional problem of unconfined seepage towards semi‐infinite slopes are described. The analysis employs complex variable techniques. Conformal mappings have been used to reduce the problem to solving an ordinary differential equation. The resulting integrals are presented in terms of special functions. The solutions for the location of the phreatic surface and the exit point have been obtained in parametric form. Some additional results and asymptotic expansions of the solutions are also presented. The numerical results have been calculated and plotted for different values of the slope angle in dimensionless co‐ordinate

ISSN:0363-9061    

DOI:10.1002/nag.1610150405

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractDilatancy and contact surface damage are important phenomena affecting the behaviour of rock joints and other geological discontinuities. Effective constitutive laws that incorporate these behaviours have recently been developed but require the specification of new material parameters that govern damage of asperity surfaces. Determination of the parameters that control damage is currently a difficulty that confronts practitioners. This brief will summarize the findings of Hutson and Dowding's investigation of joint surface asperity degradation and elaborate on the implications for application.

ISSN:0363-9061    

DOI:10.1002/nag.1610150406

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610150407

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610150401

出版商:John Wiley&Sons, Ltd    

年代:1991

数据来源: WILEY