黄土高原丘陵沟壑区不同土地利用模式对土壤机械组成和速效养分影响分析

通过对黄土高原丘陵沟壑区不同土地利用模式土壤机械组成和速效养分的测定,论述黄土高原丘陵沟壑区不同土地利用模式对土壤机械组成和速效养分的影响。结果表明：草地的在两个土层速效养分含量差别不大,而其他土地利用模式0-20cm土层的速效养分含量均高于20-40cm土层。关中土壤的速效养分明显高于黄土高原丘陵沟壑区,草地的速效养分都低于其它土地利用模式。黄土高原丘陵沟壑区土壤机械组成分布大致为：粉粒>细砂粒>粗砂粒≈粘粒。速效养分只与0-20cm的粘粒含量承显著正相关。     

流固耦合的多元结构深厚覆盖层透水地基的力学特性

深厚覆盖层多元结构坝基在渗流过程中各土层力学差异明显，分析时关注的具体问题也不尽相同，需要深入研究。基于比奥固结理论，考虑土体的非线性流变以及土体固结变形过程中孔隙度、渗透系数、弹性模量及泊松比的变化；借助ADINA流固耦合模块来模拟西藏达嘎水电站坝基渗流场与应力场耦合过程，分析各层力学特性及相互作用。研究表明，透水性较强的表层土体是渗流主要通道，也是渗流进出区和沉降变形体现区，应在上游采取措施提高其压缩模量，下游区域增设反滤层和排水设施；坝基中的粉细砂层是坝基沉降的主要原因，对坝基沉降起主导作用，同时应注意其液化特性对坝基的不利影响；坝基中的承压含水土层对下游上部结构产生向上顶托力，若位置较深，则破坏性较小；坝基深部土层对整个坝基的渗流破坏影响较小，但对沉降和渗流量的影响不可忽视；表层砂卵砾石层和粉细砂层的渗透系数相差较小时，土层间不会发生接触冲刷。此外，还发现坝基孔隙水压力在快速衰减阶段被消散，期间土体固结较快。垂直防渗墙能有效降低渗透坡降和渗流量，将坝基沉降变形控制在防渗墙上游区域，但上游坝基变形对防渗墙产生较大的水平推力，应加大防渗墙尺寸或者采用辅助渗控措施。     

基于摩尔库仑准则的膨胀土弹塑性本构模型及其数值实现

膨胀土的应力应变关系与含水量的变化有关，通过室内试验对膨胀土的变形、强度以及膨胀参数与含水量之间的关系进行研究，以湿度应力场理论为基础，提出了一个具有工程实用价值的基于摩尔库仑准则的膨胀土弹塑性本构模型。依据FLAC3D数值模拟软件所提供的二次开发程序，给出了该膨胀土弹塑性本构模型二次开发程序过程的基本原理以及模型的程序框图。结合渗流软件计算的湿度场分布，进行膨胀土基坑边坡实例验算，验证了该本构模型的正确性。     

基坑开挖及降水对坑外地表沉降的影响

考虑降水、支护结构变形以及基坑隆起3个因素引起的基坑周围土体的沉降,根据降水引起土体沉降的机理,运用修正的分层总和法单独计算出由降水引起的周围土体沉降。通过研究基坑开挖引起坑外土体沉降的规律,推导出由基坑开挖引起的坑外土体沉降理论公式。把降水引起的沉降及基坑开挖引起的沉降进行叠加,加入修正系数,最终以简化的理论公式合理地计算出基坑周围土体沉降。具体工程验证表明,推导的理论解析解与实测数据十分接近,能有效预估基坑周围土体沉降,为施工方案编制提供可靠的理论依据,最大限度减少基坑施工对周围环境的影响。     

An Analysis of Thick Plates underIn-plane and Transversal Loadings by the BEM

In accordance with the behaviours of thick plates under the in-plane and transversal loadings,and introducing the concept of equivalent load, the coupled equations for the problem have been deduced with the theory of BEM in this paper.Thus a new method is presented for solving the problems of interaction of superstructure and foundation and subsoil,as well as for the problems of the thick plates under the complicated loadings.     

农业灌溉作用下黄土边坡失稳引起耕地流失分析

为了明确在大面积农业灌溉作用下，水分入渗土壤进而渗入下部黄土体，改变临空耕地黄土边坡的稳定性状态，造成边坡失稳引起耕地流失的过程。在统计分析甘肃天水耕地流失面积、农田灌溉面积、地质灾害数量和由地质灾害造成耕地流失比例的基础上，在典型地层剖面上采集原状土壤和黄土试样，进行天然状态和灌溉作用下土体的物理力学性质和抗剪强度试验，采用理正岩土边坡稳定性分析系统，利用基于极限平衡条分法的瑞典法进行边坡稳定性定量分析。结果表明：在天然状态下，该边坡稳定性系数为1.074，处于基本稳定状态；而在灌溉作用下，随着水分入渗深度的增加，稳定性系数逐步降低，最后失稳。因农田灌溉仅使土壤层饱和，对该边坡稳定性影响不大；当灌溉水持续入渗使饱和层土体厚度大于2 m时，该边坡稳定性降低一个等级，处欠稳定状态；当饱和层厚度大于10 m时，该边坡失稳，发生滑坡，造成耕地流失。     

Analysis on Mechanism of Drain and Consolidation of Super Soft Soil

The ground treatment method for very soft soil do not satisfy the enineering needs presently. This paper studies the drain and consolidation mechanism for ground treatment method improvement of the super soft soil. It aims to obtain some varying laws of engineering properties during the super soft soil consolidated. By quantities of test data, the varying laws of the porosity, permeability, compressibility, consolidation properties and pore pressure, and their varying micro_mechanism during the seepage and consolidation of super soft soil are initially studied. Some mechanism of permeation and consolidation of super soft soil are ascertained. It concludes that the varying laws of above engineering properties is related each other, and the governing mechanism are the varying laws of the porosity and the pore pressure.     

基础尺寸对碎石土地基扩底基础上拔承载力影响的现场试验研究

影响基础上拔承载能力的因素包括地基土物理力学参数及基础尺寸参数,而确定混凝土方量最小、基础上拔承载力最大的基础参数配比是基础优化设计的关键。以戈壁滩碎石土地基中的原状土扩底基础为研究对象,采用正交设计方法,以立柱直径、深宽比、扩展角为影响因素,以基础上拔承载力为分析指标,设计出9组尺寸的足尺基础。通过现场试验,获得了各试验基础的荷载位移曲线和上拔承载力值,提出了采用渐变率的概念表征荷载位移曲线的非线性变化特征,通过分析发现基础荷载位移曲线渐变率与承载能力呈负相关。结合正交试验分析结果,得出立柱直径、深宽比、扩展角3个因素中对碎石土地基原状土扩底基础抗拔承载能力的影响程度由大到小依次为深宽比、立柱直径、扩展角,表明在戈壁滩碎石土地基基础的工程设计中增加深宽比能提高基础抗拔承载能力。     

Vergleich von Methoden zur Bestimmung der Wurzellängendichte bei Kulturpflanzen

Comparison of methods to determine the root length density of crops
In this paper, in a first step a comparison of the soil core or monolith method with the profile wall method was undertaken with data obtained for sugar beets.
Results show that differences between both methods, expressed as a factor, decline destinctly during the vegetation period. This means that the calibration of the profile wall method with the help of a time independent, average factor cannot be recommended.
In a second step, we compared the monolith method with a new procedure to estimate root growth.
Results for a soil derived from loess show that values measured and estimated correspond very well, while for a sandy soil, there was only a satisfactory correspondence.
The comparison led to the conclusion, that in field work the monolith method should be preferred to the profile wall method, and the root growth estimation procedure is available alternative to determine the root length density of cereals.     

On Elasto-Plastic Consolidation Settlement of Saturated Soft Clay

The specific properties of soft clay are characterized by higher void ratio, lower permeability and higher compressibility, the consolidation settlement of soft clay is affected by the imposed stress history, the stress paths, the consolidation pressure and the soil properties. In this paper, the porous media theory based on the mixture theory was applied in the study on the consolidation settlement of soft clay, which was more rigorous than the conventional consolidation settlement theory and the coupling between soil and water can be taken into account in the analysis.     

三种不同类型土壤对Cr(Ⅵ)的吸附特性

为了解Cr(Ⅵ)在土壤中的迁移转化规律,探明Cr(Ⅵ)在土壤中的吸附行为,采用室内振荡平衡法,以褐土、潮土以及黄绵土为研究对象,研究振荡时间、温度对土壤吸附Cr(Ⅵ)的影响。结果表明：(1)不同类型、不同层次土壤对Cr(Ⅵ)的吸附平衡时间和吸附量不同。3种供试土壤的振荡平衡时间顺序依次为黄绵土>潮土>褐土；在吸附平衡24 h时,3种供试土壤的吸附量顺序依次为潮土>褐土>黄绵土(2)随着温度的升高,吸附量逐渐下降,不同类型的土壤下降速度不一样。3种供试土壤对Cr(VI)的吸附量下降速度的顺序为潮土>黄绵土>褐土。3)3种供试土壤吸附Cr(Ⅵ)的等温线均符合 Freundlich方程和 Langmuir方程,但Freundlich方程的拟合效果更好。(4)3种供试土壤的吸附都是非自发的(ΔＧ＞０),且放热(ΔＨ＜０)的化学吸附过程。     

The Practice of Expansive Soil Judgment in Xiangtan-Shaoyang Expressway

Aiming at expansive soil judgment in Xiangtan-Shaoyang Expressway, the attribute recognition model based on objective weight is developed in this paper. The verification and application of this model indicate that the methodology is coherent to that of the Specifications for Design of Highway Subgrades and the fuzzy synthetic evaluation method. Because the attribute recognition theory would well determine some kind of synthetic evaluation problem with fuzzy attributes and its confidence criterion is developed in terms of some evaluation sets with ordered characteristics, furthermore,this model uses objective weight as the weight of the evaluation indices, decreases the subjectivity of weight decision, and ensures the objectivity of evaluation, thus the evaluation results are much more reliable.     

西南黄壤坡耕地保护性耕作的土壤结构效应

设置两种保护性耕作措施,通过6a持续试验,研究了保护性耕作措施对黄壤结构性状的影响,为西南黄壤地区保护性耕作技术应用与发展提供理论依据。[方法]分别用环刀法、干湿筛法测定土壤容重和土壤团聚体组成,土壤机械组成采用MS2000激光粒度分析仪测定,并计算出土壤孔隙度和团聚体破坏率。 [结果]结果表明：(1)垄播沟覆轮耕与免耕秸秆覆盖两种保护性耕作措施均可降低黄壤容重,增加土壤孔隙,且此作用是由表及里的渐进过程,垄播沟覆措施的土壤容重优化作用要优于免耕覆盖,而免耕覆盖对较深层次土壤孔隙状况优化效果更显著。(2)保护性耕作可提高0～20 cm土壤＞0.25mm干筛团聚体含量,水稳性团聚体含量处理之间差异不显著,但0～20cm层含量略大于20～40cm层。(3)保护性耕作可提高土壤团聚体稳定性,降低团聚体破坏率,免耕覆盖措施对提高土壤团聚体稳定性具有更加显著的效果。[结论]该试验证明了保护性耕作对黄壤土容重、孔隙、团聚体等结构性状有一定的改善作用,这种改善作用是一个非常漫长的由表及里的渐进过程,为西南黄壤地区保护性耕作技术应用与发展奠定了坚实的基础。     

灌溉条件下长期定位施肥对塿土剖面养分分布特征的影响

对塿土12年连续施肥后土壤剖面养分分布的研究发现,施肥使有机质、全P在耕层（0～20cm）与CK比较有不同程度的增加;施肥可以显著影响0～200cm土壤剖面有机质的含量;PK处理土壤剖面存在P素适度下移,120～220cm全磷含量呈现峰值;施肥对塿土耕层及0～300cm剖面全K含量几乎无影响;塿土粘化层可以减缓养分的下移;氮磷钾化肥与有机肥配合施用,使土壤NO3--N与CK比较有适度增加,对培育土壤肥力有利。     

复合土钉支护转角有利影响范围

基坑复合土钉墙转角处有明显的空间效应，受力变形较小，对支护结构有利，但不清楚转角定量的有利影响范围，目前设计中仍按照与基坑中部一样保守设计，为在此范围内降低土钉用量，避免保守设计，对水泥土搅拌桩复合土钉支护结构建立了全尺寸整体三维有限元模型，这种模型包含基坑的转角，能考虑基坑的空间效应，通过建立接触面单元，能考虑土体和搅拌桩、土体和土钉的相互作用，量化分析了基坑转角对支护结构受力和变形的有利影响范围，计算结果表明，基坑转角对开挖面水平位移、地表沉降、坑底隆起、土钉轴力的有利影响范围分别约为1.3、1、1、1.2倍的开挖深度。经与实际工程现场实测值对比，验证了该模型分析结果的可靠性，同时分析结果优于平面二维和局部三维有限元模型，结论为复合土钉支护结构的优化设计和安全施工提供了理论依据和研究方法。     

Boundaty Element Method for Analysis of Thick Plates on Two- Parameter Elastic Foundations

This paper discusses the Reissner's plates on elastic foundation.The elastic foundation is considered as two- paramerer and its effect to thick plates are taken into account by a set of govering differential equations. According to the foundamental solutions for bending problem on two- parameter foundation derived, three boundary integral equations denoted by generalized displacement functions are established. This method is suitable to solve the bending problem of thin or thick plates on two- parameter foundation with arbitary boundary condition, arbitary shape and arbitary load conditions     

钝化剂对卷丹百合镉含量及生理特性的影响

为降低卷丹百合镉含量,以生物炭、生石灰和蛇纹石为钝化材料,通过盆栽试验,探究钝化剂对土壤和卷丹百合不同器官镉含量的影响,并对相关生理指标进行检测。结果表明,3种钝化剂使土壤镉含量分别降低了11.8%、33.0%、17.1%,有效态镉降低了13.3%、26.7%、13.3%,pH分别提高了0.32、0.48、0.43。根、鳞茎、地上茎、叶、花镉含量在添加生物炭的情况下分别降低了8%、22%、15%、24%、2%,在添加生石灰的情况下分别降低了25%、30%、29%、34%、22%,在添加蛇纹石的情况下分别降低了19%、26%、16%、32%、26%。此外,3种钝化剂使丙二醛的含量分别降低了32.60%、51.20%、34.09%,脯氨酸含量分别降低了8.32%、16.76%、10.5%,过氧化氢酶活性分别增加了9.83%、18.12%、10.76%,超氧化物歧化酶活性分别增加了17.37%、38.76%、18.78%,过氧化物酶活性分别增加了9.42%、23.62%、10.68%。研究表明,3种钝化剂都能有效降低土壤和卷丹百合各器官的镉含量,提高植株抗镉胁迫能力,综合考虑生石灰的降镉效果最好。     

Analysis on Foundation Pit Deformation of a Commercial Building in Hangzhou

The foundation pit deformation of a commercial building in Hangzhou is calculated by using calculation method related to foundation pit deformation. The calculation results by m method show that the maximum deformation is 29.2mm and the real maximum deformation is 174.6mm. The deformation character obtained by foundation coefficient method is different from the real deformation. There are lots of factors influencing foundation deformation. According to practical engineering condition, in this study, the influencing factors for soil parameters, bracing condition, condition for insertion of retaining wall into soil and construction speed are determined. The calculation method used is analyzed and modified. Finally, a useful and valid method for calculating foundation deformation is presented, by which the foundation pit deformation in practical project can be forecasted and analyzed.     

黄土高原内蒙、山西土壤钾素的初步研究

内蒙、山西地区土壤钾素的分布状况是:(1)内蒙古鄂尔多斯台地各种类型土壤的速效钾和缓效钾的含量低于河套地区各种类型的土壤;(2)山西省西山黄土丘陵区、中部各盆地土壤的速效钾和缓效钾由北向南逐渐增加.从大范围各种类型土壤的速效钾和缓效钾与砂粒呈负相关:就某种土壤而言与有机质呈正相关.山西省各种土壤的速效钾在土壤剖面分布符合幂回归,而缓效钾在剖面呈低谷或凸形分布.     

安塞黄土丘陵区人工草地生产力与土壤水分特征

摘 要 人工草地建设是半干旱黄土丘陵区生态建设与农业生产的重要组成部分,比较不同类型人工草地生产力、土壤水分差异,可为草地建设中草地类型的选择与管理提供依据。通过比较川地与山地不同类型草地生产力、土壤水分年季变化差异,表现为以下特征：川地人工草地0-100cm土壤含水量受季节降雨量影响变化较为活跃,为活跃层。100-350cm土壤含水量与根系利用有关,为次活跃层。350-500cm季节变化不大,为相对稳定层。柳枝稷与苜蓿草地350-500cm土层干燥化明显。在2004-2005年,各草地4月到9月0-200cm土壤储水量减少,9月到11月0-200cm储水量增加,200cm以下各草地间差异明显,但季节变化量接近。山坡不同类型草地0-100cm土壤含水量表现为秋末高于春季,100-500cm不同季节均未显示明显的水分亏缺现象。