晋中南上新世红土物理性质及成因分析

通过对榆社、石楼、介休、襄垣的上新世红土进行野外工程地质调研,观察其野外分布概况,结合室内土工试验对4个研究区域的上新世原状红土样和上覆第四纪黄土样进行物理参数测试。在前人研究的基础之上,根据上新世红土和第四纪黄土的沉积特征和颗粒组分分布特征的一致性,反推出红土的风积成因类型。根据实测红土物理参数值,确定晋中南上新世红土为黏土或粉质黏土;该地区红土的液限和红土中黏粒含量呈线性关系,塑性指数和红土中黏粒含量呈指数关系。研究成果为晋中南上新世红土的工程性质研究提供了可靠的基础数据。     

强夯处理红粘土沉降试验研究

红粘土作为高填方体的底层地基,处理其沉降和不均匀性沉降是高填方工程研究的重点。以某机场红粘土高填地基的处理为例,通过沉降分析和方案比选开展强夯处理试验研究。根据场区内不同覆土厚度,采用不同能级进行强夯处理试验确定了合理的施工工艺和参数。通过施工中沉降观测,施工后地基土的物理力学指标试验、载荷试验和工后沉降观测,强夯处理取得了良好的效果,满足设计要求。指导大面积施工时,在质量、造价、工期上都取得了成功。     

印度尼西亚红土型镍矿

红土型镍矿分布在环太平洋亚热带-热带多雨地区。镍矿体产于趟基性岩上部的红土风化壳中,受地形控制明显,成因类型为红土型硅酸镍氧化矿,以褐铁矿型和腐岩型为主,矿石质量和可利用性均较好。     

Towards understanding the behaviour of naturally-occurring road construction materials

Summary Naturally-occurring road construction materials generally contain a greater amount of fines, and the fines have a higher plasticity than traditional materials such as a crushed rock aggregates. This makes their behaviour more difficult to understand and predict since soil suction and fabric become important controlling factors. The concepts of suction and fabric are outlined, and their role in controlling the behaviour of road construction materials is illustrated by a fundamental laboratory study of a lateritic gravel and two calcrete gravels. These materials have successfully been used as road base construction materials in low-volume bituminous-surfaced roads in Kenya and Botswana. It is concluded that the presence of fines can be an advantage, since they allow significant suctions to develop and also reduce the permeability.     

试论红土化作用及红土的工程地质分类

本文主要讨论了红土化作用的科学定义及其与风化作用的关系。在此基础上依红土化作用程度对红土进行了工程地质分类。     

Micromorphological and chemical complexities of a lateritic profile from basalt (Jos Plateau, Central Nigeria)

A ferricrete-capped lateritic profile developed on basaltic saprolite is described.

Within both ferricrete and the immediately underlying soft laterite, two types of sesquioxidic cement are distinguished: the isopachous goethitic intergranular cement which is predominant and is interpreted as an indication of past phreatic conditions; and the Fe-stained meniscus cement which is interpreted as a sign of vadose conditions.

The observed features are suggested to reflect changing drainage conditions related to morphological rejuvenation of the profile, in full accordance with previous hypotheses developed on the basis of geomorphological consideration.     

中国南方红土型金矿床地质特征

我国南方红土型金矿属改造红土型金矿,进一步可分为古层间构造带淋积型、岩体接触带淋积型及岩溶洼地堆积型三个亚类,以及蛇屋山式、龙形寨式、大坊式、北衙式、百色式、老万场式及镇圩式等七个矿床式。各类矿床在产出的构造部位、成矿作用、含金红色风化壳剖面、金矿源体及金的产出特征上有其自身的特征。同时指出了我国南方红土型金矿的时代、地理及地貌分布特征。     

A water balance study in lateritic terrain

The water balance of a 600 m² field site on a lateritic hillslope in Kerala, southwest India, has been studied during two southwest monsoon seasons. Surface runoff was of minor importance while infiltration and evapotranspiration were the major components amounting to approximately 2/3 and 1/3 of the rainfall, respectively. Groundwater response was rapid, involving fluctuations of several metres. Recharge mechanisms hypothesized are water movement via preferred pathways from the ground surface to the capillary fringe where rapid rise in groundwater level is brought about by a transmitted pressure pulse. Groundwater recharge was found normally to take place during the southwest monsoon season only. the field study demonstrates that seasonal shallow groundwater recharge representing the major portion of the rainfall May, be observed in this lateritic terrain in the humid tropics. It indicates a good potential for further groundwater development. Moreover, conditions are conducive to a considerable contribution to possible recharge to deeper aquifers. the observed groundwater recharge is the result of a complex process on which further research will throw more light.     

印尼苏拉威西超大型红土型镍矿找矿标志

超大型红土型镍矿主要控矿因素,板块边界三联点构造控制的白垩纪、三叠纪、二叠纪蛇绿岩底部镁质超基性岩,基岩MgO/Fe0比值14～18,通过风化作用后,形成结构分带较好的风化壳,风化壳对数Mgo/全铁比值0.4～1,地貌20～400米标高、5～ 20度坡度角,中、低山面型地貌.     

赣西红土型金矿床地质特征,成矿地质条件和找矿前景分析

赣西红土层分布广泛,红土风化壳具有典型的红土剖面特征,红土型金矿主要形成于杂色粘土带中,分为蛇屋山式和大坊式两类。矿体呈线型—面型分布,以层状、似层状、透镜状产出,产状较平缓。矿石构造为土状、花斑状、角砾状,矿床规模小—中型。通过分析红土型金矿构造地貌条件与红土风化壳、含金矿源体、卡林型金矿的关系,认为在萍乐坳陷带中成矿条件较好,含金矿质来源丰富,构造相对稳定,地貌多低山丘陵,对成矿有利。并指出萍乐坳陷带中与卡林型金矿母岩风化有关形成的红土区是寻找红土型金矿最有利的地区,认为赣西红土型金矿具有较好的找矿前景。