9A

Surface properties Permeability and capillarity

871062 Influential factors of friction bet~een steel and dry sands Uesugi, *I: Ki~heda, H Soils Found I26, :\'2, Ju~w 196'6, P33-46

Simple shear tests ,,,,ere used to stud,', the friction between steel and air dried sands. Sand type and surface roughness of the steel significantly affected the friction coefficient, whereas nor- mal stress and mean grain size of the sand were of little signifi- cance, The shear deformation of the sand mass was unaffected b,v the surface roughness of the steel.

Physico-chemical properties

871063 Isothermal phase change model for freezing and thawing soils. 1: development Hromadka. T V Environmental Software VI, :\'2, Sept I986, Pl13-117

A simple computer model has been developed, capable of determining the thermal and moisture status of a two dimen- sional system subjected to thawing and freezing processes, as encountered in cold regions.

871064 Isothermal phase change model for freezing and thawing soils. lI: model Hromakda, T V: Yen, C C Environmental Software V], N2, Sept 1986, Pl18-123

A Fortran computer program is available which accommo- dates two dimensional heat and soil water flow models as cou- pled by an isothermal phase change model. It can analyse two dimensional freeze/thaw problems, provided sutticient input information on modelling parameters, boundary and initial conditions is available, A special data preparation program PROTO0 is described, which is used to develop the data input file.

871065 Relations bet,~een permeability and electrical conductivity in granular aquifers Huntley, D Ground Water I'24, N4. July-Aug 1986, P466-474

To clarify permeability-resistivity relations, laboratory experi- ments were carried out using simulated sand aquifers. Results suggest matrix (surface) conduction effects are at least as important as porosity-permeability relations. Only weak rela- tions were seen between true formation factor and permeabil- ity. Relations between apparent formation factor and permeabilit~ hold only at constant fluid conductivity. The con- sequences of these findings to currently used practices are discussed.

871066 Thermally stimulated currents in rocks Doioglou-Revelioti, E; Varotsos, P J Geophys V59. N3, Aug 1986, P177-182

Seven rock samples, representing the mean crustal structure of Greece, were selected. During gradual variation of tempera- ture, in the absence of any external electric field, all samples gave rise to a transient electric current in the range 0.01-1 nanoamperes, which reached a maximum around room tempe- rature. A tentative physical model, based on piezoelectric and pyroelectric effects, is suggested to explain observed results.

See also. 8-123S. ,~'7132~)

871067 Measurement of the porosity (communicating ~oids) of hydraulic concrete (In French) Berissi, R: Bonnet, G: Grimaldi. G Bull Liaison Lab Ponts Chaussees N142, March-April I936. P59-67

A new nondestructive method of measuring the porosity of concrete or porous rocks has been developed. A partial vac- uum is created on the surface using a suction cup, and the time dependency of the return to atmospheric pressure is moni- tored. A parameter. T. the response time is measured, which characterises the porosity. The method, its theoretical base and equipment are described. The hygrometric state of the medium affects T. and should be determined to correct the measured value of porosit 3.

87 ! 068 Macroporosity and permeability of some soil cores from England and France Douglas, J T Geoderma I'37, N3, Juh 1986. P221-231

A study of soil pores is reported, that used simple counting and dye-staining techniques. Visual examination of channels and fissures in soil cores provided an enhanced description of soil structure in terms of functional porosity compared with that available from values of air-filled porespaee. Variation in measured permeability- accounted for by measuring pore dimensions ranged bct~cen 58 and 88% for four sets of sam- ples from three soils: in contrast, the range of wtriation accounted (or by variation in air-filled porespace was 10 to 48%. A straightforward assessment of size and occurrence of soil macropores should be attempted whenever describing soil structure, and representative sizes of samples should be col- lected for studying fluid transmission characteristics of soils. Auth.

871069 Dependence of effective porosity on fracture continuity in fractured media Gordon, M J Ground Water V24..V4. July-Aug 1986, P446-452

Fractured media are often considered to behave as equivalent porous media continua. The equivalent continuum effective porosity measured on a small rock volume may differ signifi- cantly from that measured on a larger volume, depending on the relative degree of fracture continuity in the region consid- ered. Numerical analysis considers a grossly simplified fracture system. With poor fracture continuity at the location and scale of interest, flow is dominated by the intact rock matrix, result- ing in a higher effective porosity. For a similar case with unin- terrupted fracture continuity, effective porosity may be lower due to fracture dominated flow.

871070 Finite difference grid for a doublet ~ell in an anisotropic aquifer Miller, R T; Voss, C I Ground Water V24, N4, Ju(v-Aug 1986, P490-496

An Aquifer Thermal Energy Storage (ATES) system is being evaluated in an anisotropic sandstone aquifer in Minnesota, USA. A finite difference model grid has been developed for the doublet well pump-injection system. As a finite difference grid of the whole system ,,vould pro`"e too costly to model, flow net

i ~ 1986 Pergamon Journals Ltd. Reproduction not permitted