水工混凝土结构CAD系统设计

基于新修订水工结构设计规范的水工混凝土结构ＣＡＤ系统，以中文Ｗｉｎｄｏｗｓ为操作平台，采用先进高效的ＶＢ语言和面向对象的程序设计方法，具有良好的人机交互界面．本文详细介绍水工混凝土结构ＣＡＤ系统的总体设计原则以及文件系统、结构分析、素混凝土、钢筋混凝土、预应力混凝土。

弹性模量与结构频率相关的动力模型相似律

根据材料的弹模与结构频率有关的特征 ,提出了修正物理模型相似比尺及换算原型量的公式 ,实例分析表明换算结果更符合实际。

水工结构挡土墙设计和应用

挡土墙在如今水利工程中发挥重大作用,主要是为了能够有效预防上游发生边坡塌方、倒毁等情况。因此本研究结合润河水利工程项目的水土结构挡土墙设计应用情况展开实例研究,结合该工程项目提出水利工程挡土墙的设计标准,并对挡土墙的构造措施以及应用技术要求进行概述,为类似水工结构挡土墙的设计应用项目提供参考价值。

关于地下室外墙的结构设计的简析

随着城市经济的快速发展,城市建筑群的建设速度,为了能合理利用有限的空间,建筑物会设计地下室或地下车库等地下设施,本文主要阐述:地下室外墙的设计要求与其安全性能,分析普通地下室与人防地下室外墙设计区别,提出外墙设计应注意的主要事项。

薄壁大圆筒码头水工挡土结构施工方法研究

针对薄壁大圆筒结构形式码头传统施工工艺技术要求高，施工困难等特点，提出施工的新方法。该方法具有施工安装方便，工期短，造价较低等优点。

新老混凝土粘结断裂韧度计算方法探讨

本文在新老混凝土粘结试件三点弯曲切口梁断裂试验的基础上 ,对影响新老混凝土粘结面断裂性能的主要因素进行了显著性分析 ,其各因素对粘结断裂韧度影响的显著性大小依次为界面粗糙度、界面剂类型、粘结龄期、混凝土强度、混凝土粗骨料最大粒径等 ,并推导出新老混凝土粘结断裂韧度的多因素计算公式 。

多槽体渡槽的自振特性分析

应用三维动力有限元方法 ,对某多槽体渡槽自振特性进行了分析 ,重点分析了其自振频率、振型、动力放大系数的特点 ,得出了一些有意义的结论 .

Effect of soil moisture gradient on structure of broad-leaved/Korean pine forest in Changbai Mountain

A 112 m×8 m sample pot which includes 14 sub-plots was set up along the slope in Hongshi Forestry Farm of Baihe Forestry Bureau (127°55′E, 42°30′ N), Jilin Province in August 2002. Community structure, soil moisture contents at 0–10 cm and 10–20 cm in depth, water content of litter as well as the contents of C, N and P of litter, living leaves and branches in the broad-leaved/Korean pine (Pinus korraiensis) forest were measured in each sub-plot on different slope positions. The analytical results showed that there existed an obvious soil moisture gradient along the slope: upper slope <middle slope< lower slope. The difference in soil moisture contents on different positions of slope led to a change of the stand structure of the braod-leaved/Korean pine forest. The proportion ofQuercus mongolica gradually increased with the decrease of soil moisture content and that of other major tree species in the broad-leaved/Korean pine forest gradually decreased or disappeared. The dynamic of soil moisture contents in the litter layer was as same as that in mineral soils. The decomposition rates of the litter on different slope positions were different and the dry weights of existent litter varied significantly. The soil nutrients in the litter on the lower slope was richer than that on the upper slope due to the different stand structure on the different slope positions. The moisture content and nutrient contents of soil had effects on the composition, decomposition, and the nutrient release of litter, thus affecting stands growth and stand structure and finally leading to the change of ecosystem. Key words Soil moisture gradient - nutrient - Stand structure - Broad-leaved/Korean pine forest CLC number S718.5 Document code A Foundation item: This study was supported by the NKBRSF (G1999043407-1), Tackle Key Problem of Science and technology of China (2001BA510B-07), Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-406, SCXZD0101), NKTRDP (2001BA510B-07. 2002BA516A20).Biography: WANG Yan (1970-), female, Ph. D, associate professorResponsible editor: Song Funan

受弯构件叠代法简化配筋计算

受弯构件正截面强度计算，采用叠代法配筋，是以钢筋混凝土受弯构件不同破坏情况的临界点为基准，计算出临界配筋截面积，然后采用叠代的方法，反复计算受压区高度及渐近配筋截面积至所需为止。本文介绍了单筋矩形和Ｔ形截面、双筋矩形和Ｔ形截面的叠代计算方法，该法简单，能使繁复的计算过程有效地简化，便于修改，可优化结构降低造价，成果精确可靠。

Modeling Soil Water Retention Curve with a Fractal Method

Many empirical models have been developed to describe the soil water retention curve (SWRC). In this study, a fractal model for SWRC was derived with a specially constructed Menger sponge to describe the fractal scaling behavior of soil; relationships were established among the fractal dimension of SWRC, the fractal dimension of soil mass, and soil texture; and the model was used to estimate SWRC with the estimated results being compared to experimental data for verification. The derived fractal model was in a power-law form, similar to the Brooks-Corey and Campbell empirical functions. Experimental data of particle size distribution (PSD), texture, and soil water retention for 10 soils collected at different places in China were used to estimate the fractal dimension of SWRC and the mass fractal dimension. The fractal dimension of SWRC and the mass fractal dimension were linearly related. Also, both of the fractal dimensions were dependent on soil texture, i.e., clay and sand contents. Expressions were proposed to quantify the relationships. Based on the relationships, four methods were used to determine the fractal dimension of SWRC and the model was applied to estimate soil water content at a wide range of tension values. The estimated results compared well with the measured data having relative errors less than 10% for over 60% of the measurements. Thus, this model, estimating the fractal dimension using soil textural data, offered an alternative for predicting SWRC.

Formation and Water Stability of Aggregates in Red Soils as Affected by Organic Matter

The water stability of aggregates in various size classes separated from 18 samples of red soils under different managements, and the mechanisms responsible for the formation of water-stable soil aggregates were studied. The results showed that the water stability of soil aggregates declined with increasing size, especially for the low organic matter soils. Organic matter plays a key role in the formation of water-stable soil aggregates. The larger the soil aggregate size, the greater the impact of organic matter on the water stability of soil aggregates. Removal of organic matter markedly disintegrated the large water-stable aggregates (> 2.0 mm) and increased the small ones (< 0.25-0.smm) to some extent, whereas removal of free iron(aluminium) oxides considerably destroyed aggregates of all sizes, especially the < 0.25-0.5 mm classes. The contents of organic matter in water-stable aggregates increased with aggregate sizes. It is concluded from this study that small water-stable aggregates (< 0.25-0.5 mm) were chiefly cemented by Fe and Al oxides whilst the large ones (> 2.0 mm) were mainly glued up by organic matter. Both free oxides and organic matter contribute to the formation and water stability of aggregates in red soils.

An Experimental Analysis of Water and Soil Conservation Effected by Micro-landscape Structure

[Objective] This comparative experiment was to explore the soil loss con- trol effects under cultivation combination of different soil and vegetation types, and to provide scientific basis for the upcoming pilot project of ecological recovery. [Method] Both the rudiment of water locomotion functioned by micro-landscape structures and different spatial combinations of various landscape constituents are considered, thus, the combination of multi-soil type, crop species and site conditions is designed in three different experimental sites. [Result] Soil loss estimates in experiments in South Wello significantly depended on various soil type, slope, vegetation and type of con- servation structure; grass cover tremendously reduces soil loss; legume cultivation performed better than cereal cultivation in soil loss control. [Conclusion] By conduct- ing the data analysis of the experiment, a scientific reference is proposed to the agri- culture planting and protective mode for the alleviation of water and soil loss in Amhara Region, Ethiopia.

Site quality evaluation of loblolly pine on the South Carolina Lower Coastal Plain,USA

Eleven soil types, which can be identified and delineated using conventional soil survey procedures, were characterized for loblolly pine （Pinus taeda L.） productivity. Four 4-hectare study sites, each containing four measurement plots, were established for every soil type studied. In a stepwise multiple regression, both soil parent material （i.e. a combination of subsoil texture and geology） （p〈0.001）, and drainage class （p=0.006） were significant predictors of site index （tree age 25）, and the overall linear regression model had an R2 value of 0.55. The extremes of soil parent material differed by 3.9 m site index （loamy subsoil on the Wicomico-Penholoway surfaces versus clayey subsoil on the Pamlico-Princess Anne surfaces）. Each increment of drainage class differed by 0.7 m site index. For example, a poorly drained soil had 0.7 m lower site index than a somewhat poorly drained soil. For seven of the eleven soil types studied, there is greater than 80% probability that estimated mean site index is within ±0.8 m of the actual soil type mean site index. The other four soil types （labeled G, I, C and K） need to be either redefined or sampled more intensively. Two of these need to be subdivided in order to adequately characterize site quality, one based on geology （Soil type G） and one based on soil drainage class （Soil type I）. Variation in soil drainage class and varying amounts of topsoil displaced into windrows were both factors influencing site quality variation of a third soil type （Soil type C）. The wide variation in site index data for a fourth soil type （Soil type K） appeared to be due, in part, to sampling study locations and individual measurement plots with less than optimum bedding and/or artificial drainage. Soil parent material （subsoil texture and geology） along with drainage class were found to be important factors influencing site quality on the South Carolina Lower Coastal Plain.

Kinetics study and analysis of zeolite Y destruction

A series of zeolites,including USY zeolites without sodium,Na-USY at different Na contents,La-USY with different rare earth（RE） contents and La-Na-USY with RE and Na were prepared by an ion exchange method.They were investigated to understand the activation barriers for the destruction of Y zeolite structure under hydrothermal treatment and the effect of V using the solid-state kinetic model.The results showed that the pathways for Y zeolite destruction were dealumination,desiliconization and the disappearance of La-O bonds.Zeolites were destroyed by steam through acid hydrolysis,which was accelerated by V.In addition,Na and V exerted a synergistic effect on the framework destruction,and the formation of NaOH was the rate-determining step.The presence of RE elements decreased hydrolysis and stabilized the structure of the zeolites.The interaction between V and RE destroyed zeolite structure by eliminating the stabilizing La-O[RE-OH-RE]^（5＋）bridges in the sodalite cages.

Effects of Soil pH，Texture，Moisture，Organic Matter and Cadmium Contenton Cadmium Diffusion Coefficient

The supply of cadmium from soil to plant roots mainly depends on the diffusion process. This work was conducted tostudy the effect of some soil properties on cadmium diffusion coefficient (D) in soil. Measurements were made using the Shofield and Graham-Bryce's isotopic labelling method. Cadmium diffusion coefficients varied from 10￣(-7) to 10￣(-9) cm￣2s￣(-1),Higher values were observed in acid sandy soils and lower values in calcareous clay soils. Liming an acid soil resulted in a sub-stantial decrease of D. Addition of cadmium as nitrate salt generally increased D, while addition of sewage sludge and organ-ic matter resulted in a significant decrease of cadmium diffusion. The rhizospheric activity also induced a moderate reduction in D. The relationships between D 10￣(-9)cm￣2s￣(-1)) on the one hand and soil PH, moisture (Mc, g kg￣(-1)), organic matter (OM, gkg￣1 ), clay (Cy, g kg￣(-1)) and cadmium content (Cd, mg kg￣(-1)) on the other were obtained by the multigle regression:D=182. 1-29.g1 pH+0.210Mc-0.303OM+0.011Cy+1.64Cd (R￣2=0.859,n=22 ).

Low secondary compressibility and shear strength of Shanghai Clay

In order to investigate the compressibility, particularly the secondary compression behaviour, soil structure and undrained shear strength of Shanghai Clay, a series of one-dimensional consolidation tests （some up to 70 d） and undrained triaxial tests on high-quality intact and reconstituted soil specimens were carried out. Shanghai Clay is a lightly overconsolidated soil （OCR=1.2-1.3） with true cohesion or bonding. Due to the influence of soil structures, the secondary compression index Ca varies significantly with consolidation stress and the maximum value of C~ occurs in the vicinity of preconsolidation stress. Measured coefficients of secondary compression generally fall in the range of 0.2%-0.8% based on which Shanghai Clay can be classified as a soil with low to medium secondary compressibility. The effect of soil structures on the compressibility of Shanghai Clay is found to reduce with an increase in depth. Soil structure has an important influence on initial soil stiffness, but does not appear to affect undrained shear strength significantly. Undrained shear strengths of intact Shanghai Clay from compression tests are approximately 20% higher than those from extension tests.

Exploring Soil Layers and Water Tables with Ground-Penetrating Radar

Ground-penetrating radar (GPR) has been used predominantly for environments with low electrical conductivity like freshwater aquifers, glaciers, or dry sandy soils. The objective of the present study was to explore its application for mapping in subsurface agricultural soils to a depth of several meters. For a loamy sand and a clayey site on the North China Plain, clay inclusions in the sand were detected; the thickness, inclination, and continuity of the confining clay and silt layers was assessed; and a local water table was mapped. Direct sampling (soil coring and profiling) in the top meter and independent measurement of the water table were utilized to confirm the findings. Also, effective estimates of the dielectric number for the site with the dielectric number of moist clayey soils depending strongly on frequency were obtained. Thus, important properties of soils, like the arrangement and type of layers and in particular their continuity and inclination, could be explored with moderate efforts for rather large areas to help find optimal locations for the time-consuming and expensive measurements which would be necessary to detail a model of the subsurface.

Simulation of Random Crack Generation in Concrete Members with Uniform Stress Fields

The randomness of strength and deformation of concrete material is serious and should be considered both in theoretical analyses such as Finite Element Methods and engineering practice, specially for those structural members with a uniform stress field, where stresses or strains are approximately the same under loading. A mathematical ap- proach of producing a series of random variables of the ultimate tensile strain in concrete is proposed to describe the randomness ofconcrete deformation. With reinforced concrete finite elements a real model calculation method is found for the randomness of initial cracks determined by a minimum tension strain within the uniform stress fields of concrete members. The proposed methods in our paper have as aim to improve the existing method used by FEM and other rela- tive approaches, which normally pay less attention to randomness with consequences that may possibly differ from testing or practice. The method and sample computation as indicated is meaningful and comply with testing and engi- neering practice.