沙地果树节水渗灌技术的试验研究

果树渗灌是灌溉水通过特殊的透性材料持续缓慢地渗入并浸润土壤，借助土壤毛管水运动原理向果树根系供水。干旱地区沙地渗灌能有效地减少地表蒸发、避免无效渗漏造成的水分损失，提高灌溉水利用率，从而达到节水的目的。在沙地果园采用节水渗灌技术，比传统的大水漫灌和沟灌方式分别节水８３．１％和６３．１％。     

怒江迪庆州陡坡耕地的改良和持续利用研究

滇西北的怒江、迪庆两州地处云南省高寒高山峡谷区，地形破碎而陡峻，耕地稀缺，陡坡种植业占有很高的比重。由于人口的增长，陡坡耕地仍将作为该地区的主要耕地长期存在。这种传统的耕种方式已对环境产生了深刻的负效应。本文根据其生存条件和利用现状就通过改良以取得持续利用的方向和途径作了初步探讨。     

塔克拉玛干沙漠土壤沙化发生条件及对土壤性状影响

土壤沙化是土壤发育逆向演替恢复母质特性的过程，土壤沙化发生条件可以概括为４个方面：土壤干旱是沙化的根本条件、植被衰败为风沙活动创造了条件、土壤质地轻是沙化物质基础、大风和频繁起沙风是沙化的动力条件。土壤沙化结果使土壤粗粒化、贫瘠化，同时也使土壤含盐量降低。     

宝鸡某场地污染土的分析评价

宝鸡某场地由于长期堆放食盐，造成地基上污染、通过勘察，查明了污染土层，进行了腐蚀性测试和评价，对场地污染区与非污染区土的物理力学性质指标进行了对比，并分析了土的污染机理，提出了防护措施。     

Modelling of soil temperature profiles using data from the pilot experiment at Anand

We present some preliminary results from a multi-layer soil temperature finite-difference model using the data set obtained during the pilot experiment on land surface processes at Anand. We hope that the present results will prove useful during the final field experiments scheduled for the coming monsoon season.     

Electrokinetic remediation of metal contaminated glacial tills

This paper presents the results of an experimental investigation which studied the feasibility of using the electrokinetic process to remediate contaminated clays of glacial origin, otherwise known as glacial tills. An overview of the electrokinetic phenomena, as well as previously performed laboratory and field investigations, is first presented. The methodology of the electrokinetic experiments which were conducted to investigate the removal of metals from a glacial till is then described. A total of 16 experiments were conducted using glacial till samples obtained from a project site near Chicago. Sodium and calcium were used as the surrogate cationic metallic contaminants. These experiments demonstrated that ion transport during the electrokinetic process occurs due to both electro-osmosis and electromigration, but that due to electromigration is significantly higher than that due to electro-osmosis. Unlike other clays such as kaolinite, the glacial till used for this investigation possessed high buffering capacity because of its high carbonate content which prevented the acid front migration from the anode to the cathode during the electrokinetic process. The ion removal efficiency of the electrokinetic process was found to increase when: (1) the voltage gradient applied to the soil was increased, (2) the initial concentration of the contaminants was increased, and (3) the duration of the treatment process was increased. The ion removal efficiency was also greater for smaller ions which possess less ionic charge and when the ions existed independently in the soil as compared to when they coexisted. This investigation suggests that the electrokinetic process has significant potential for remediating glacial tills contaminated with metals. However, the properties of Na and Ca are not representative of contaminants, such as heavy metals, so further investigations are needed.     

Parameters of Land-Surface Processes for Gobi in North-West China

Using data from the intensive observation period (May–June 2000) of the NWC-ALIEX (The Field Experiment on Interaction between Land and Atmosphere in Arid Region of North-west China), the characteristics and mechanisms of some key land-surface process over Gobi in a typical arid region of north-west China are analyzed and several parameters of land-surface processes are calculated. The weighted mean of the surface albedo over a typical arid region of the Dunhuang Gobi is calculated using the relative reflection as a weighting factor, and its value is 0.255 ± 0.021. After removing the influence of precipitation, the mean soil heat capacity over a typical arid region of the Dunhuang Gobi is 1.12 × 10⁶ J m^-3 K^-1,which is smaller than that observed in the Heihe (China) River basin Field Experiment (HEIFE). The mean soil heat diffusivity and conductivity are about half of those observed in HEIFE.     

Space-time mapping of soil salinity using probabilistic bayesian maximum entropy

The mapping of saline soils is the first task before any reclamation effort. Reclamation is based on the knowledge of soil salinity in space and how it evolves with time. Soil salinity is traditionally determined by soil sampling and laboratory analysis. Recently, it became possible to complement these hard data with soft secondary data made available using field sensors like electrode probes. In this study, we had two data sets. The first includes measurements of field salinity (EC_a) at 413 locations and 19 time instants. The second, which is a subset of the first (13 to 20 locations), contains, in addition to EC_a, salinity determined in the laboratory (EC_2.5). Based on a procedure of cross-validation, we compared the prediction performance in the space-time domain of 3 methods: kriging using either only hard data (HK) or hard and mid interval soft data (HMIK), and Bayesian maximum entropy (BME) using probabilistic soft data. We found that BME was less biased, more accurate and giving estimates, which were better correlated with the observed values than the two kriging techniques. In addition, BME allowed one to delineate with better detail saline from non-saline areas.     

In-plane and anti-plane strong shaking of soil systems and structures

The concept of in-plane and anti-plane shaking is introduced with a rigid block on a plane surface with Coulomb friction. Using a hypoplastic constitutive relation to model the mechanical behaviour of the soil, numerical solutions for a rigid block on a thin dry or saturated soil layer are obtained. The coupled nature of dynamic problems involving granular materials is shown, i.e. the motion of the block changes the soil state—skeleton stresses and density—which in turn affects the block motion. Motions of the block as well as soil response can be more realistically calculated by the new model. The same constitutive equation is applied to the numerical simulation of the propagation of plane waves in homogeneous and layered level soil deposits induced by a wave coming from below. Experiments with a novel laminar shake box as well as real seismic records from well-documented sites during strong earthquakes are used to verify the adequacy of the hypoplasticity-based numerical model for the prediction of soil response during strong earthquakes. The response of a homogeneous earth dam subjected to in-plane and anti-plane shaking is investigated numerically. In-plane and anti-plane shaking is shown to cause nearly the same spreading of a sand dam under drained conditions, whereas under undrained conditions anti-plane shaking causes stronger spreading of the dam. The dynamic behaviour of a breakwater founded on rockfill and soft clay during the 1995 Kobe earthquake is back-calculated to show the good performance of the proposed numerical model also with a structure. Section 9 deals with buildings on mattresses of densified cohesionless soils or fine-grained soils with granular columns, slopes with ‘hidden’ dams and structures on piles traversing clayey slopes to show the suitability of hypoplasticity-based models for the earthquake-resistant design and safety assessment of geotechnical systems.     

渍水麦田土壤水分动态模型研究

根据土壤水分平衡原理，建立了一个反映土壤渍水、可与小麦生长模型耦合的土壤水分动态模型，尤其考虑了因地下水位较浅而引起的毛管上升水量和土壤导水率的变化对土壤含水量的影响。采用盆栽小麦水分试验资料验证了日蒸散量的模拟值，利用湖北荆州农业气象试验站和江苏金坛农业气象试验站的土壤水分历史资料对建立的模型进行了综合测试和验证，结果表明:蒸散量、地下水位和0～50 cm土壤含水量的模拟值与实测值具有较好的一致性，模型能可靠地预测多雨和渍水地区麦田土壤水分的变化动态