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61.
D. M. Orazulike 《Natural Hazards》1993,7(2):109-119
Field and chemical data show that soils in some parts of Bauchi State, Nigeria, are rich in illite (20–35%), montmorillonite (60–75%), and kaolinite (45–73%). These expansive clays cause the soils to shrink and swell alternatively in response to the seasonal supply of moisture; resulting in observed damaging cracks. Plasticity index (PI) determinations on these soils are high (7–13.4%) suggesting that they are potentially hazardous. The attendant hazards and huge losses to the State are blamed on the expansive nature of these soils. The hazardous conditions can be mitigated by adopting proper construction precautions as well as by using chemical additives such as lime and phosphates, to lower the PI and help to increase the strength of the soils. 相似文献
62.
63.
Summary In many parts of the world, particularly in humid tropical regions, residual soils are abundant. In this paper the suitability of a residual lateritic soil as a construction material is investigated, with respect to its strength and compaction characteristics. In comparison with other typical construction fills available in Southeast Asia, compacted lateritic soils produce excellent shear strengths and CBR values. However, the brittleness and tensile cracking of this compacted material become enhanced on the dry side of the optimum moisture content, or if excessive compaction is imparted. Nevertheless, at a moisture content of 2% wetter than the optimum, the tensile mode of failure is suppressed and the lateritic fills become ideally suited for the construction of high embankments and impervious dam cores. 相似文献
64.
65.
SOILSHEARSTRENGTH:ANINDICATORFORERODIBILITYOFTHELOESSSOILSWANGGuiping;WEIZhongpingandZHANGZhiguoAbstract:FieldexperimentSunde... 相似文献
66.
Soil hydrophobic effects on infiltration and catchment runoff 总被引:1,自引:0,他引:1
After dry summers or drought, eucalypt forest soils at two sites in southeastern Australia developed hydrophobic or non-wetting surface characteristics that reduced infiltration, measured using a sprinkling infiltrometer. At one site the development of hydrophobic conditions caused the rainfall to runoff conversion efficiency of a forested catchment to increase from 5 per cent to 15 per cent. Under non-hydrophobic conditions at this site, grassland always generated more runoff than forest. However, one major rainfall-runoff was recorded at a time of highly hydrophobic forest soil conditions and this storm generated greater runoff on the forested catchment than the grassland catchment. At the second site forest soils have naturally highly conductive surface layers because of a dense network of macropores and pathways for preferential flow. Hydrophobic conditions produced by drought caused soil water movement to be confined to only a few of the larger macropores exposed to surface ponded water. Even so, infiltration rates remained relatively high so that the impacts of hydrophobic soils were not translated into increased catchment runoff as at the first site. 相似文献
67.
F. Amini 《Soil Dynamics and Earthquake Engineering》1995,14(6):439-443
Two types of clayey soils, a kaolinite and a bentonite, were tested using a resonant column apparatus under random excitation conditions. The concept of root mean square (rms) strain was utilized for the purpose of strain calculations during random loading. The conventional estimator of the transfer function was used for random vibration analysis. The effect of confinement duration (at a constant pressure) on dynamic soil properties, namely damping and shear modulus, was evaluated. The results indicate that for both cohesive soils, the effect of time was less pronounced during random vibration than sinusoidal loading at the same rms strain. This effect is however more pronounced when the peak shearing strain of sinusoidal loading is considered. Furthermore, time effects were more pronounced at low strain levels than at high strain levels. 相似文献
68.
J. S. Choudhari 《Journal of Earth System Science》1987,96(3):203-210
Arid soils with slight variations in parent material, vegetation and climate were studied for their morphological, chemical
and mineralogical characteristics. Results show that the soils are at different stages of profile development. Varying degrees
of pedogenic features have been tied up with data on palaeoenvironment to develop a relationship between the soil and age
of the landform. Studies reveal that Dune and Shergarh sandy soils with least degree of manifestation belong to early Holocene
to latest Pleistocene, whereas Chirai sandy soil with weakly developed B horizon belongs to the upper Holocene. Soils (Khajwana
and Gajsinghpura) with well-developed B horizon and a calcic layer with lime segregations belong to mid-Pleistocene whereas
Pali and Pipar soils with illuvial clay in B horizon belong to early Pleistocene. 相似文献
69.
Very soft organic harbour mud is increasingly used as a filling and construction material in harbour construction and reorganization.
The undrained shear strength of such soft sediments is the critical geotechnical soil parameter with regard to any specific
construction design. Field and laboratory vane shear testing is a standard method to quickly determine this important parameter.
So far, the effect of rod friction on vane shear tests in very soft organic soils is unclear. In this study we present results
from laboratory experiments on harbour mud from a construction site in northern Germany. Relations among vane and rod geometry,
penetration depth, water content, rod friction and undrained shear strength are derived. Based on these relations the influence
of rod friction on vane shear test results is investigated. The results indicate that field and laboratory vane shear test
measurements may be significantly influenced by rod friction. Methods are proposed to correct for the rod influence, which
is shown to increase with rising water contents. 相似文献
70.
从水泥土的固化机理出发,结合水泥搅拌桩桩身标准贯入试验和水泥土配合比试验,分析讨论了土性指标、土质条件和地层性质对水泥搅拌桩成桩质量的影响。 相似文献