摘要:

AbstractA computational procedure is developed for solving the problem of a circular hydraulic fracture propagating under the action of frac‐0fluid being pumped in at a central wellbore. The crack is modelled as continuous distributions of ring dislocations and the resulting elasticity singular integral equation is solved numerically. The fluid flow equations are approximated by local and global interpolation finite difference schemes. The coupling between elasticity and fluid flow is handled numerically, by, two different algorithms: one iterates on crack tip velocity whereas the other varies the time step size until it agrees with the chosen increment in crack length. Sample results are given; it is found that the velocity algorithm is computationally more, efficient and more stable. The model allows detailed tracing of pressure distribution and fluid flow in the fracture, even under complex conditions of cyclic injection and fluid rheology. It may serve as a stand‐alone model of (horizontal) hydrafracs–especially at shallow depths–or it may be used as a reference frame to test the various numerical formulation/algorithms required for the ongoing development of a fully 3‐D hydrafrac

ISSN:0363-9061    

DOI:10.1002/nag.1610090102

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractOn the basis of the two‐dimensional theory of elasticity, the theoretical analysis of a vertical, fluid‐filled crack intersecting and oblique joint has been made for the extraction of geothermal heat from hot, dry rock masses, where the opening of the joint near a point of intersection and the frictional resistance against slips along the joint are taken into account. The stress intensity factors are evaluated for discussing crack kinking at the upper joint tip, and the sufficient conditions on theinclination of the joint and on the length between the upper joint tip and the point of intersection are obtained for keeping a fluid‐filled crack stable just beneath a joint. It is also shown that the volume of the stable reservoir created by using a joint is much larger than that of a fluidfilled crack in a jointless rock mass, even if the joint is oblique and is opened up by the fluid pre

ISSN:0363-9061    

DOI:10.1002/nag.1610090103

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA modified version of the bore hole sheat device (BHSD) was used to obtain field consolidation curves in a soft sensitive clay. The Porewater pressure dissipation was monitored at the centre of one of the shear plates.This paper describes briefly thein situdevice employed and demonstrates the basic features of the linearelastic F. E. program ‘SOL’. A detailed study is made to simulate the field behaviour with the finite element approach. Comparisons are made between the field and analytical consolidation behaviour. Difficulties in predicting the value of the coefficient of consolidation of a sensitive clay using the BHSD consolidation curves are discus

ISSN:0363-9061    

DOI:10.1002/nag.1610090104

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractIn this paper, a general variational principle for the initial boundary value problem of quasi‐static thermoelastic consolidation is developed by assuming infinitesimal deformation and an incompressible fluid flowing through a linearly elastic solid. By manipulating the coupling operators, an extended form of the variational pronciple is derved. The associated finite element formulation based on this principle is presented and numerical applications for plane strain thermo‐elastic consolidation are revea

ISSN:0363-9061    

DOI:10.1002/nag.1610090105

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA simple rate‐dependent tension model, tailored primarily for rocks in ground‐shock calculations, has been constructed. It is formulated as an internal state variable theory with spherical void development taken to approximate the underlying dissipative micromechanism. This simplifying assumption of ductile, rather than brittle, damage growth has been made to enhance the practicality of the model for large‐scale problems. The model has been restated within the fromework of (strain‐softening) viscoplastcity to associate it with the desirable mathematical properties of the latter theory. The tension option, extended to include healing in the post‐damage compressive phase, has been implemented in a standard cap constitutive routine and is referred to as the visco‐damage tension model. Model parameters are selected for a shale‐like material. Results of uniaxial shock‐loading strain‐rate calculations exhibit desired characteristics in tension. Damage‐related hysteretic effects are illustrated through cyclic loading calculations. It is planned to develop more effecient computational procedures to facilitate adoption of the model into large‐scale ground shock calculations. Anisotropic extensions of the model wi

ISSN:0363-9061    

DOI:10.1002/nag.1610090106

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThe plate loading test is performed in order to determine the deformation modulus of a rock massin situ.In the standard execution of this test the loading is applied perpendicular to the rock surface. The displacements are measured on the axis of symmetry, since for an isotropic material with linear deformation characteristics exact formulae are known which are valid at this location. For horizontal strata this presents no problem as it is easy to provide loading in a vertical direction. When the rock strata are dipping it is imprectical to use nonvertical load and it is then necessary to calculate the modulus from the displacements in a non‐axisymmetrical arrangement. Using the well‐known method of the Taylor series approximate formulae are derved which are sufficiently accurate for all practical cases of sloping r

ISSN:0363-9061    

DOI:10.1002/nag.1610090107

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610090101

出版商:John Wiley&Sons, Ltd    

年代:1985

数据来源: WILEY