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Abstract: A prospective model of dorsal-fin spine growth in chondrichthyans is devised by studying the growth of spines from captive and wild Heterodontus portusjacksoni injected with several fluorochromes. Evidence was [...]

ABSTRACT We investigated evidence for bias in estimates of abalone density from the point-nearest-neighbor (PNN) diver survey method wherein divers measure distances between abalone and from random points to nearest [...]

ABSTRACT Growth of 'stunted' greenlip abalone in areas with low maximum sizes was enhanced over 6 mo by reducing their natural density and by translocation to habitats supporting faster growing [...]

ABSTRACT Cultured Haliotis laevigata (Donovan), 18 mo old, were tagged and seeded at either high or low densities on boulder reefs (4-6 m depth) at Cape Jervis, South Australia in [...]

This article discusses the effects of leaching on soluble soil particles. Topics include permeameter testing, foundation engineering, and soil liquefaction.

The criteria directing silty sand shear strength are discussed and rated. These include whether the fines are plastic or nonplastic, and how sandy soils are categorized, which helps calculate load deformation resistance and friction rates.

A discussion is presented comparing the advantages and disadvantages of using piles or piers to stabilize soil slopes. Topics include minimization of moment and shear forces and vibrations caused by driving piles, as opposed to drilling piers.

An exploration is presented on the impact of mine subsidences on surrounding structures. Settlement cracks were observed near structure corners, rather than their centers; recommendations for releveling include the installation of thin reinforcing plates, hydraulic jacks, and strap retrofitting applied to foundation walls.

Different types of failures are examined for excavated slopes in clay soils. These include surficial failures, degree of slope-face weathering prior to excavation, desiccation cracking and slaking due to drying and wetting, and seepage parallel to the slope.

A study on the development of a modified Newmark model for determining the permanent displacement of slopes in earthquakes is evaluated. It is argued that other cases exist where earthquake deformation is underpredicted. Two examples are presented. The first involves the reduction of shear strength during the California Northridge earthquake on Jan 17, 1994. Another involves slope movement caused by loose cohesionless soil deformation.

Authors M.C. McBrayer, M. Mauldon, E.C. Drumm and G.V. Wilson conclude their study on the hydraulic conductivity of compacted clay subjected to cycles of of wetting-drying or freezing-thawing with the observation that cracks due to these cycles do not fully heal upon hydration. Several other studies, however, have shown that cracks due to wetting-drying or freezing-thawing cycles actually do heal completely upon wetting. The type of clay mineral is believed to be a significant factor in the healing of cracks upon wetting.

The purpose of this paper is to describe the settlement behavior of posttensioned slab-on-grade. The two case studies illustrate that the amount of damage to the structure depends on how the posttensioned slab-on-grade deforms. For the first case study, about one-half of the posttensioned slab-on-grade was unaffected by soil movement and remained relatively level, whereas the remaining one-half of the slab settled. This caused the development of a slab crack and hinge point, where moderate damage occurred in the area parallel to the slab crack. The Skempton and MacDonald settlement criteria and the severity of damage versus foundation deformation parameters were applicable for this case. For the second case study, which was the settlement of deep fill, there was a tendency for the posttensioned slab-on-grade to tilt uniformly (no hinge point). This resulted in substantially less damage than the first case study, even though the maximum differential settlement was greater for the second case. The severity of damage versus foundation deformation parameters were not applicable for this case. One advantage of posttensioned slab-on-grade that was common for both cases was that the slab cracks were relatively small, due to the posttensioning (compression) effect, which enabled the slab to resist the tension forces due to fill settlement.

A seven-step procedure to be used in determining the severity of ground-movement-related building damage based on approximate crack width may be inaccurate when cracking is hidden or patched or when other factors contribute to the crack widths. The severity of the damage should be based on a number of factors, which include crack widths, differential settlement, and angular distortion of the foundation.

A study was conducted on the confining pressure-caused crushing of granular particles. Results show that particle crushing is reduced by enhancing mineral hardness and that smaller amounts of breakage for a given stress is achieved with stronger or harder particles. Results are consistent with those obtained from the crushing of sedimentary rock-derived oversized particles.

Laterally-loaded drilled shafts in clay have been modeled. Construction data reveal that shafts are usually short and stubby and frequently behave as rigid parts when experiencing lateral loads. However, lateral load tests are not performed in a majority of scenarios for the design of laterally loaded shafts, mainly due to cost constraints posed by field tests.

The authors' method of characterizing the consolidation and desiccation process in fine-grained soil after deposition suffers from the assumption of a uniform evaporation rate and a single surface drying event. These limit its applicability since it does not take into account changes in the soil properties caused by cycles of wetting and drying. In addition, it does not consider evaporative drying resulting in surface shrinkage cracking.

Robert W. Day argues that the presence of loose debris or a disturbed zone at the bottom of the small-diameter boring is a serious disadvantage for Sandra L. Houston et al's method of in-situ test for collapsible soil. Sylvio R.M. Ferreira et al examine the techniques used with both apparatus and present data on these soils, focusing on the flooding method used and the comparison between in-situ collapse under a plate inside an auger boring and laboratory collapse obtained in an oedometer test.

Pumping can occur when clay is compacted wet of optimum. Rather than densifying, the clayey soil squeezes out from underneath the compaction equipment. Adding gravel to the clayey soil creates a granular skeleton that increases the undrained shear strength. The results of this study show that even a partial gravel skeleton can prevent pumping of a clayey soil. Pumping occurred during the modified proctor compaction test when the undrained shear strength was less than 14 kPa (290 psf) and the initial tangent modulus was less than 1,600 kPa. To prevent pumping, the tested clayey soil (sand and montmorillonite mixture) had to contain at least 63% rounded gravel or 54% angular gravel. A lower percentage of angular gravel prevented pumping because it more effectively interlocked and created the necessary gravel skeleton at a lower density than the rounded gravel.