Environmental effects, weathering and soil formation

904007 Effect of antecedent freeze-thaw frequency on runoff and soil loss from frozen soil with and without subsoil compaction and ground cover Edwards, L M; Burney, J R Can J Soil Sci V69. N4, Nov 1989, P799-811

Three soils, loam, sandy loam, and fine sandy loam, from Prince Edward Island, Canada, were tested in the laboratory using a rainfall simulator. Soils were tested after 10 days con- tinuous freezing and after 5 cycles of 1 day freeze/l day thaw. The continuously frozen samples showed nearly 3 times the sediment loss and runoff of the cycled samples. Incorporation of organic residue or surface cover decreased sediment loss, soil compaction caused increase. Greatest loss of fine sediment fraction was from the loam, then the fine sandy loam.

904008 Autogenic and allogenic denudation in carbonate karst by the multiple basin method: an example from Svartisen, North Norway Lauritzen, S E Earth Surf Process Land VI5, N2, March 1990, P157-167

Karst denudation is generally evaluated on the basis of solute content measurement on runoff water. Karst basins are often not autogenic and denudation rates assuming solute contribu- tions proportional to areal ratio of karst terrain can lead to errors. This problem can be solved by calibration of the allogenic contribution to runoff hardness, either directly or using a mixing model. A linear model of uniform mixing appr- oach is applied to data from subarctic striped karst of North Norway. Results are consistent with those of other methods.

9O4009 Erosion processes and rates for gullies in granitic soils, Bathurst, New South Wales, Australia. Short communication Crouch, R J Earth Surf Process Land VIS, N2, March 1990, P!69-173

Bathurst Granite on the Central Tablelands, NSW, weathers to give a landscape of low hills dominated by convex slopes. The residual soils are highly susceptible to gully erosion. Ero- sion rates from fluted gully sides were measured over a 3 year period, using erosion pins and survey. Annual rates varied from 0-53ram over short distances, with an average close to 20mm, about 4 times that for sheet or rill erosion. Splash ero- sion was a major component on ridge crests.

904010 New technique for measuring evaporation from the ground surface Watanabe, K; Tamaki, H; Matsushima, S Proc 2nd International Symposium on Field Measurements in Geomechanics, Kobe, 6-9 April 1987 V2. P1027-1036. Publ Rotterdam: A A Balkema, 1988

An exact measurement of evaporation rate is necessary in groundwater investigation prior to shallow disposal of radio- active waste. A practical technique for measuring evaporation rate from the ground surface is proposed, based on the fact that evaporation must increase humidity in the air above the ground surface. Distribution of relative humidity, wind veloc- ity and temperature are measured in a wind tunnel and values used to calculate evaporation rate. Laboratory and field tests illustrate applicability of the technique.

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904011 Undersea lateritic soils and their formation of engineering properties in Dalian new harbour Qu, Y X; Zhang, Z X; Xu, X L; Wu, Z L Proe International Conference on Engineering Problems of Regional Soils, Beijing, 11-15 August 1988 P686-688. Publ Beijing: International Academic Publishers, 1989

Seabed lateritic soils were discovered in the Dayao Gulf in northern China. The red-brown clay and yellow-brown loam soils have high natural water content, liquid limit 63.5%, and void ratio greater than 2. They show poor engineering proper- ties, with low strength and high compressibility, and low cohe- sion and friction angle. The formation of these soils and relation of engineering properties to parent rock composition and accumulation processes are discussed.

Earthquake mechanisms and effects

See also: 904362

904012 Semi-empirical approach for predicting strong ground motion Zheng, T; Yao, Z X; Xie, L Geophys J VI00, NI. Jan 1990, P9-18

Data from the Tangshan region of China show source processes have considerable effects on ground motion for small earthquakes. A semi-empirical method for predicting strong ground motion using records of small events as empiri- cal Green's functions is presented in order to remove these source effects. Numerical experiments are used to validate the proposed procedure.

904013 Behaviour of rocks at great depth related to Tangshan earthquake Tao Zhen-yu; Zhang Li-ming Proe International Symposium on Rock at Great Depth, Pau, 28-31 August 1989 VI, P489-493. Publ Rotterdam: A A Balkema, 1989

The mechanism of the tectonic earthquake is discussed, and the sequence of the Tangshan earthquake is simulated by com- puter modelling using a plane strain finite element analysis and a visco-elastic-plastic material model. Some mechanical parameters of very deep rock are evaluated and some under- standing gained of deep rock behaviour.

Frost action, permafrost and frozen ground

See also: 904227

904014 Frost bursting: a violent expression of frost action in rock Michaud, Y; Dionne, J C; Dyke, L D Can J Earth Sci II26, NIO. Oct 1989, P2075-2080

Rapid fracturing of basaltic rocks has been observed under certain conditions in subarctic Quebec. The term 'frost burst- ing' is proposed by analogy to rock bursting. It occurs when intact and massive rock is saturated and subjected to intense and rapid freezing. Hydrostatic pressures developed in pore or crack space allow strain energy to be stored in the rock. If the material is stiff and strong enough to exhibit release of a large quantity of stored strain energy, frost bursting can occur.

1990 Pergamon Press pie. Reproduction not permitted