Evaluation of connectivity characteristics of naturally jointed rock masses

154A 933117 Phenol removal from kaolinite by electrokinotics Acar, Y B; Li, H; Gale, R J J Geotech Engng Die ASCE Vll8, N i l , Nov 1992, P18371852 The use of electroosmosis to remove phenol from saturated kaolinite specimens has been investigated. The clay was loaded with contaminant, below the maximum adsorption capacity, in the dry state. Flow behaviour and electrochemistry in the experiments are described. 85-95% of the adsorbed phenol was removed by the treatment. Initial indications are that electroosmosis may be a practical method of removing low levels of organic pollutants from cohesive soils. 933118 Rock m ~

and the interpretation of anisotropy of

magne~ susceptibility Rochette, P; Jackson, M; Aubourg, C Roe Geophys V30, N3, Aug 1992, P209-226 The conventional rules for interpretation of AMS in terms of microstructure and deformation are subject to many exceptions. Certain magnetic minerals can give rise to inverse or intermediate magnetic fabrics. Where more than one magnetic mineral is present, quantitative inferences on intensity of preferred orientation and strain on the basis of AMS are impossible. Magnetic memory effects and natural remanence may also influence AMS. Alternating field or thermal demagnetization effects on AMS are discussed. Techniques specific to AMS interpretation must be developed. These will rely mainly on relations of susceptibility to magnetic field and temperature and on anisotropy of remanence. 933119 Tramlent electrical activity accompanying rock under indentation loading Enomoto, Y; Hashimoto, H Teetonopkysics V211, N1/4, Sept 1992, P337-344 The geoelectrodynamics of rocks associated with fracture has been examined in indentation tests on granite and andesite. Charges generated were detected either by a conductive indenter or by an electrode set at a specified distance from the indentation zone. High electric charge signals were detected during the loading cycle, lower charges due to stress relief on unloading. The far field tests detected an electric charge propagating through the rock during fracturing. Possible mechanisms of charge generation and propagation are discussed. 933120 Exploration methods for nuclear waste repolitorles or mineral deposits - from source to sink, where's the fronff Mohamad, D B; MacKenzie, A B; Stephens, W E; Russell, M J Trans lnst Min Metall (Sect B Appl Earth Sci) VIOl, SeptDec 1992. PB139-B146 In study of low temperature mineral occurrences or performance of radioactive waste repositories, one requires a geochemical or biogeochemical model to describe the transport of elements in solution through a varying geochemical environment. Of particular interest is behaviour of elements at natural or radiolytically produced redox fronts in a rock, where dissolution or deposition may lead to the formation of certain mineral deposits or the retardation of radionuclide transport. A study is reported of U and Th distributions and natural decay series disequilibrium about a redox front in granite in Scotland. Results are discussed in the context of large scale aqueous transport of uranium in the region and compared with data from Brazil.

933121 Influence of mineralogy on the durability of Drakensberg basalts van Rooy, J L Proc Tentk Regiosal Cmtferemce for Africa el .Soil Meclmics and Foumlmi~ EsgiKeri:q ami tke Tkird Intermuimud Conference on Tropical awedResidmd Soils, Maseru, 23-27 September 1991 V1, P383-392. Publ Rotterdam: A A Baikema, 1991 Chemical weathering plus slaking disintegration can cause durability problems in marie igneous rocks such as the Drakensburg basalts encountered in the Lesotho Highlands Water Project. Five different basalt types were identified petrographically. These have been classified on the basis of texture, mineralogy, and alteration products. Durability estimated from index tests was correlated with petrographical characteristics. These results indicate that only one of the basalts tested appears to meet general requirements for concrete and road aggregate.

Permeability and capillarity See also: 933027, 933291 933122 Design, construction, performance, and repair of the soU-

bentonite Iimrs of two lagoons Chapuis, R P; Lavoie, J; Girard, D Can Geoteek J V29, N4, Aug 1992, P638-649 Site conditions, design, and construction of sand-bentonite liners for four lagoons are described. Although control tests were satisfactory, global performance of two of the lagoons was not, with leakage rates much in excess of design values. An analysis of the various factors affecting global performance was developed to help explain the failures, which cannot be explained by the deterministic method used in analysis. A method has been developed for analysis of the graph of total leakage rate of a lagoon to determine the location of main hydraulic defects. Repair was effected by injection of bentonite slurry. 933123 Insights on reservoir hetemgenolties and performam~ of waterflood at the Bone Creek Unit obtained from interwell tracer interpretatiom Singhal, A K; Nieuwenburg, G; Dagdick, L; Roach, N Can Pet Tedmoi V31, N8, Oct 1992, P20-28 An extensive interwell tracer pi'ogram was carried out at the Bone Creek Unit between 1984 and 1986 to obtain information about the flow distribution. Six different water soluble radioactive tracers were injected at 11 different points. Lateral and vertical heterogeneities inferred from the tracer tests were generally consistent with those from log and core data. Implications for reservoir exploitation are discussed. 933124 Evahmtlon of ¢emecttvtty ¢heraeterist~ of nataraily joimed rock masses Zhang, X; Harkness, R M; Last, N C F~lng Geoi V33, N1, Sept 1992, Pll-30 The hydraulic properties of a rock mass are strongly dependent on the connectivity characteristics of its discontinuities. Connectivity of 2D joint patterns is examined. Statistical results from in situ data show connectivity ratio increases with increases in average joint length, joint density, and interaction parameter of the joint pattern, although correlation is poor.

© 1993 Pergamon Press Ltd. Reproduction not permitted

155A Good correlation is seen between connectivity ratio and continuity index of the joint pattern, the product of the three aforementioned parameters. The size of the sampling area, generally small relative to joint length, also influences calculated connectivity. Several connectivity measures are compared for calculated flow through simulated rock masses. 933125 Evaluation of soil tep-cever systemsto minimise infiltration into a sanitary landfill, a case study Weeks, O L; Mansell, R S; McAllister, S W Esroiron GeM Water Sci V20, N2, Sept-Oct 1992, P139-151

It is essential to minimise infiltration of rainfall into sanitary landfills, and cover materials should encourage runoff and maintain vegetative growth. Three topcover materials have been evaluated at an experimental landfill: tan carbonate silt (rock tailings), sandy topsoil, and mixtures of each with bentonite. Each component of the EPA water balance equation was determined. This equation was found to severely overestimate the deep seepage, the most critical component for topcover design. The locally available rock tailings proved to be an efficient topcover material. 933126 Long-term filtration belmviour of soll-geotextile system Rao, G V; Gupta, K K; Pradhan, M P S Geotech Test J V15, N3, Sept 1992, P238-247

Geotextile filters must retain soil whilst maintaining sufficient hydraulic conductivity. A permeameter has been developed in which long term flow rate measurements and gradient ratio tests can be carried out simultaneously. Various mixtures of evenly graded Ottawa sand/silty soil against needle punched and woven geotextiles, whose opening sizes satisfy the soil retention criteria for the mixtures chosen, have been examined in the permeameter, Unstable flow in the initial period gradually reduces until a stable flow regime is established. The time to stability increases with increasing silt content. It is suggested that long term stable gradient ratio replaces 24h gradient ratio as a design parameter. 933127 Analytical solutions for steady and transient flow in nonhomogeneous and anisotropic rock joints Amadei, B; Illangasakere, T lm J Rock Mech Mira Sci V29, N6, Nov 1992, P561-572

Continuous and differentiable analytical solutions are developed for distribution of head and velocity in rock joints with inhomogeneous and anisotropic hydraulic properties. They are based on integral transforms and do not require discretization of the joint surface into elements. Head and velocity components can be determined at any point and at any time t. Preferential and channel flow can be predicted if joint void space is characterised. It is possible to study deviations from the cubic flow law in a non-empirical manner. 933128 Hydraulic cenductivity of three geosynthetic clay liners Estornell, P; Daniel, D E J Geatech Engag Div ASCE VlI8, NIO, Oct 1992, P15921606

Three proprietary geosynthetic clay liners (GCL) have been evaluated. Hydraulic conductivities of individual sheets and overlapped pieces were measured. An effective hydraulic seal developed along the overlaps in all cases. Composite liners with a punctured geomembrane over the GCL were also tested. The best performance was when the geomembrane was

in direct contact with bentonite, without a separating geotextile layer. For GCLs with textiles on both sides, migration of bentonite was possible unless adequate filtration was provided. 933129 Case study of two horizontal wells for improved oil recovery in New Zealand Stolz, L R J Pet Tedmol V44, N9, Sept 1992, P1033-1039

Two horizontal wells were drilled in the McKee reservoir to minimise the coning problems found with vertical wells. Petrophysical logging to identify fractured and faulted zones, cementing the liner to improve isolation, and selective perforation were carried out to help optimise completion. Early gas breakthrough and subsequent gas production problems have nevertheless been found, and production and ultimate recovery are lower than expected. No further horizontal wells are planned for this reservoir. 933130 Modeling permeability in imperfectly layered porous media. I. Derivation of block-scale permeability tensor for thin gridblocks Zijl, W; Stam, J M T Math GeM V24, N8, Nov 1992, 1'865-883

Computer codes are used routinely to model flow in saturated media. The subsurface is divided into grid blocks or elements to which a homogeneous block-scale permeability tensor is assigned. Local scale permeability is heterogeneous and it is necessary to find the block effective permeability tensor for each individual block. Practical expressions are given for the 9 components of the block scale permeability tensor of a thin block, derived from the local-scale continuity equation and Darcy's law for an anisotropic layered porous medium. 933131 Modeling permeability in imperfectly layered porous media. II. A two-dimensional application of block-scale permeability Stam, J M T; Zijl, W Math Geol V24, NS, Nov 1992, P885-904

A method for calculation of the nine components of the 3D intrinsic permeability tensor on the scale of a grid block for a local scale, predominantly layered subsurface was presented in a companion paper. It is demonstrated applied to numerical examples. Two basic 2D permeability distributions are adopted, vertical succession with preferential stacking and a checkerboard concept. Results are used in derivation of guidelines to indicate situations in which higher order solutions may be neglected and where conventional harmonic and arithmetic averages give acceptable permeability values at the grid block scale. 933132 Spatial statistics for predicting fluid flow through a single rock fracture Coakley, K J Math Geol V24, N8, Nov 1992, P905-927

Void space within a fracture is modelled in terms of pixels of zero or some positive constant aperture by clipping a correlated Gaussian process. Reasonable simulation of natural joint geometry is seen. Steady state laminar flow through a fracture is predicted in terms of spatial statistics of the void space. One statistic measures how often pixels alternate from void to contact area along rows parallel to the flow direction, others measure the dispersion of voids in the rows and columns of a pattern. Flow through patterns with different void fractions is predicted.

© 1993 Pergamon Press Ltd. Reproduction not permitted