大连新港的红粘土及其工程特性的形成

在大连新港油罐区的建设中,发现了一种具有高孔隙性、高含水量、高塑性、中低压缩性的特殊土。作者对这种土及其母岩的矿物学、岩石学、地球化学、物理化学和工程特性进行了系统研究,揭示了该区红粘土及其工程特性的形成机理,该区红粘土乃是蒙脱石化的粗玄岩,在中温带气候区红土花作用的产物。     

Mineralogical and chemical composition of some Bauchi soils and their relationship to passive Earth movement

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.     

冻土切削力学特性的试验和理论分析

利用笔者所研制的冻土切削试验台，在室内对不同冻土在不同温度、含水量、切削速度、切削深度和切刀前角下进行了一系列切削试验。结果表明，切削时，冻土主要呈脆性断裂破坏，其切削过程被认为是刀刃切入和撕裂冻土的结果，切削阻力随冻土温度降低而非线性增加，随切削速度提高而略有增加，随切削深度增加而近似线性增加，最佳切刀前角随切削深度增大有增大趋势。但平均切削阻力与最大切削阻力之比值对不同试验条件基本在０．４－０．６５间变化。同时，根据切削过程机理，从理论上建立了最大切削力模型，此模型考虑了切入和撕裂冻土阻力。     

Some engineering characteristics of a compacted lateritic residual soil

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.     

SOIL SHEAR STRENGTH: AN INDICATOR FOR ERODIBILITY OF THE LOESS SOILS

ＳＯＩＬＳＨＥＡＲＳＴＲＥＮＧＴＨ：ＡＮＩＮＤＩＣＡＴＯＲＦＯＲＥＲＯＤＩＢＩＬＩＴＹＯＦＴＨＥＬＯＥＳＳＳＯＩＬＳＷＡＮＧＧｕｉｐｉｎｇ；ＷＥＩＺｈｏｎｇｐｉｎｇａｎｄＺＨＡＮＧＺｈｉｇｕｏＡｂｓｔｒａｃｔ：ＦｉｅｌｄｅｘｐｅｒｉｍｅｎｔＳｕｎｄｅ...     

Soil hydrophobic effects on infiltration and catchment runoff

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.     

Transport of water in frozen soil: V, Method for measuring the vapor diffusivity when ice is absent

A new experimental method is introduced for determining the relative magnitudes of liquid and vapor diffusion by using a small amount of soluble chemical as a tracer. The theoretical justification of the method is presented for the case where ice is absent. The feasibility of the method is demonstrated by an experiment using marine-deposited clay.     

On the stable growth of segregated ice in freezing soil under negligible overburden pressure

The stable growth condition of a segregated ice layer is studied by the use of the principle of mass and heat conservation. This condition evidently depends upon the properties of a thin transitional zone, which is believed to exist between the boundary of an ice layer and a 0[°C] isotherm. All probable models of the transitional zone are classified and the conditions for each model is derived. The effect of the small amount of soil minerals contained in an ice layer is also studied.