西藏自治区的土壤理化特性探讨

通过对西藏自治区主要土壤类型的实地踏勘和采样分析,并结合全国土壤普查资料的结果进行分析,揭示了本区土壤具有4点特性:即多砾石性、砂质性、成土幼年性和低矿化的富有机质性。因此,在改良本区土壤时,应重视去石与防治沙漠化措施,加强矿质养分肥料的施用,稳定有机肥的投入。     

西藏自治区土壤侵蚀特点及现状

西藏自治区地域辽阔,土壤侵蚀复杂多样。本文在野外调查的基础上,对西藏自治区土壤侵蚀特点作了全面论述,并对西藏自治区不同类型土壤侵蚀区的土壤侵蚀现状做了较全面的分区评价。同时取雅江中游地区19个县作为典型区域,利用1999年1:20万TM遥感图像土壤侵蚀解译结果,对该典型区域的土壤侵蚀现状作了定量评价。最后根据评价结果,对西藏自治区土壤侵蚀的发展趋势做了预测。     

Exploring some relationships between biological soil crusts, soil aggregation and wind erosion

A portable wind tunnel was used to test the contribution of biological and physical elements to overall soil aggregation on a soil dominated by biological soil crusts in south-eastern Australia. After moderate disturbance and simulated wind erosion, 90% of surface aggregates on the loamy soil and 76% on the sandy soil were dominated by biological elements (cryptogams). Lower levels of biological bonding were observed on the severely disturbed treatment. Linear regression indicated a significant positive relationship (r²=0·72) between biological soil crust cover and dry aggregation levels greater than 0·85mm. To maintain sediment transport below an erosion control target of 5gm⁻¹s⁻¹ for a 65kmh⁻¹ wind at 10m height, a crust cover of approximately 20% is required. When a multiple regression model which sequentially fitted biological crust cover and dry aggregation greater than 0·85mm was applied to the data, dry aggregation accounted for more of the variation in sediment transport rate than biological crust cover. These data were used to develop a conceptual model which integrates crust cover and dry aggregation, and provides a useful framework within which to predict the likely impacts of changes in soil crust cover and aggregation.     

Microbial production of CO2 in red soil in Stone Forest National Park

Lunan stone forest is a kind of typical karst in China, which is mainly developed under red soil. In the winter of 1999, three study sites were chosen in stone forest national park according to vegetation cover, geomorphologic location and soil types. CO2 concentration was measured with Gastec pump at different depths of soil (20, 40, 60 cm) and at the same time soil samples were gathered and soil properties such as soil moisture, pH, soil organic content were analyzed and the total number of viable microbes were counted in laboratory. In the study, dependent variable was chosen as the mean soil log (PCO2), and soil properties were chosen as the independent variables. Multiple stepwise regression analysis showed that the total amount of microbes and soil moisture are the best indicators of the CO2 production, with the equation LOG(PCO2) = - 0.039(TNM) - 0.056(Mo) + 1.215 accounting for 86% of the variation of the soil CO2 concentration, where TNM is the total number of microbes in the soil and Mo is the moisture of soil sample.     

自重固结与土层的固结状态初探

介绍了沉积厚度与时问平方根和沉积厚度与时间呈直线关系、底面不排水时沉积过程中固结的Gibson理论解答以及不考虑沉积时固结作用、底面不排水时沉积后自重固结的Terzaphi理论解答，据此分析了上述两种沉积模式不同沉积速率时目前仍处于沉积过程的土层的固结状态，求算出了停止沉积后土层固结所需的最长时问，指出业已停止沉积数百年以上的土层一般不应处于欠固结状态。     

阜新矿区地面塌陷灾害对土地生产力的影响

在研究地面塌陷对一个地区的影响时，一般只侧重于其对建筑物、铁路的影响，而对土地生产力影响的探讨和研究还不够深入。对于阜新矿区来说，地面塌陷对该区土地生产力的影响更是空白，前期的工作仅仅侧重于地面塌陷的调查，如果就地面塌陷对土地生产力的影响做一决的概括和分析，无疑会给今后治理由地面塌陷带来的灾害提供借鉴作用。本文结合大量实测、实算数据，应用土地复理论与方法对地面塌陷引起的土地侵蚀、土壤盐碱化、土壤湿度、土壤质量水平等四个方面做了较为系统的阐述，并对灾害的治理提出了见解。     

高陡土坡喷锚（土钉墙）支护施工技术

通过长沙电力学院西区永久性锚拉挡墙施工实例，介绍喷锚(土钉墙)的施工方法，质量控制关键点等施工技术．     

被污染土壤的植物修复研究

植物修复是利用植物吸收、降解、挥发、根滤、稳定、泵吸等作用机理,达到去除土壤、水体中污染物,或使污染物固定以减轻其危害性,或使污染物转化为毒性较低化学形态的现场治理技术.植物修复对于重金属污染土壤的治理修复具有重要意义.已有研究在累积与超累积植物的寻找筛选、植物对重金属等有害物的耐毒和解毒机理、植物修复现场环境调控及根际处理技术等方面取得了大量成果.现代分子生物学、基因工程技术发展有可能使植物修复技术取得重大突破.     

静力触探中土层界面效应试验研究

根据成层土模型试验结果,对静力触探中土层面效应进行试验研究和机理分析,取得了成层土界面效应的规律性,为利用静力触探划分土层提供了理论和实践依据。     

软土大变形固结计算中参数识别的遗传算法

含水量很高的饱和软土在外荷载作用下沉降很大,小变形分析误差太大,必须通过大变形非线性固结计算来模拟。遗传算法是一种全局优化和搜索的仿生算法。近年来随着工程领域中复杂的大规模非线性系统的出现,遗传算法日益得到青睐,目前已经广泛应用到各个领域中。本文对遗传算法做了改进,主要体现在杂交算子的选取和轮盘赌模型的模拟退火拉伸,并将其用于饱和软土的大变形固结分析,解决其中的关键参数识别问题。研究表明该方法是行之有效的,值得进一步研究探索。