玻璃砂透明土与标准砂土强度特性对比三轴试验

制备了不同级配的玻璃砂透明土,对其进行了三轴固结不排水剪切试验和直接剪切试验,并与同等条件下的标准砂土试验结果进行了对比分析.结果表明：玻璃砂透明土的抗剪强度随相对密度的增大而增大;标准级配玻璃砂透明土的抗剪强度比05~10mm粒径玻璃砂透明土大;相同级配下,玻璃砂透明土与标准砂土的抗剪强度相近,可用玻璃砂透明土模拟天然砂土.     

一种先进的应力路径三轴仪

介绍一种由计算机控制的权力路径三轴测试系统,该系统配备先进的压力与体积控制器,即可按应力方式加载,也可按应变方式加工,加载与测量全部自动控制,除能进行常规的应力路径和普通的三轴试验外,还可进行循环加载等复杂的应力路径试验。     

海砂土三轴试验研究

伴随着我国公路建设迅猛的发展,各种新型材料用作路基填筑已经成为热点,选择海砂土作为路基填料是充分考虑当地实际情况和现场条件的,做到真正的变废为宝.为了研究海砂土的强度特性,进行了一系列的三轴试验,试验结果表明:海砂土的粘聚力较小,内摩擦角较大,应力应变曲线大多属于应变硬化型,峰值应力不明显,强度参数随着干密度的增加而增加,12％为界限含水率.     

一种混合砂的真三轴排水剪切试验研究

通过对混合砂进行不同中主应力系数下的真三轴排水剪切试验,分析砂土在排水状态下的应力与应变、强度与变形特性,并研究偏应力、体应变、应力比,有效主应力比值随中主应力系数的变化规律。     

海砂土三轴试验研究

为了研究海砂土的强度特性,进行了一系列的三轴试验,试验结果表明:海砂土的粘聚力较小,内摩擦角较大,应力—应变曲线大多属于应变硬化型,峰值应力不明显,强度参数随着干密度的增加而增加,12%为界限含水率。     

三轴试验技术的发展与工程应用

详细阐述了三轴仪的分类、发展过程及运用,以土的强度理论为背景,详细地介绍了常规三轴仪的试验方法与其参数的选用问题,提出现在常规三轴仪本身与在试验过程中存在的问题.     

外包钢箍板加固柱混凝土三轴应力分析及应用

利用混凝土在三轴应力状态下强度变化的特征,通过在柱外包钢箍套的方法对其进行加固,从而达到提高柱混凝土强度的目的。分析了加固方法的基本原理并介绍了应用的具体实例。     

砂土常规三轴试验中若干问题的探讨

利用GDS应力控制三轴系统和常规应变三轴仪，对标准砂进行了不同围压下的常规三轴固结排水剪试验，对峰值强度、弹性模量和有效内摩擦角等参数进行了对比研究，对于接触效应的处理、控制方式的选择等问题进行了讨论。     

相似方法在冻土低温三轴压缩试验研究中的应用

主要介绍相似方法在冻土抗剪强度低温三轴压缩试验研究中的应用及若干关键科学问题。基于目前广泛应用的Bockinghamπ定理，采用量纲分析方法，并考虑冻土的本构方程、含水量与重度之间的关系，研究试件几何尺寸、试验控制条件、土性指标及冻土变形应力、应变之间的相似关系，求解冻土抗剪强度指标的相似解析式。据此，可由某一条件下冻土抗剪强度指标的试验测定结果，推求其他条件下冻土抗剪强度指标的相似计算值。试验结果表明，所得的冻土抗剪强度指标的相似解析式具有很高的推求计算精度，能够很好地应用于冻土工程及相关科学研究。     

自动应力路径三轴仪的研制

本文介绍采用气体压力控制装置进行给定位应力路径试验的自动控制三轴试验系统，该系统全部采用国产化元器件，操作简便，可靠性高。     

温控土工三轴仪的研制及其应用

为了研究温度对土的力学性质的影响,研制了一套温控土工三轴仪。该设备采用模块结构,体小轻巧;实现了三轴仪与恒温箱的巧妙结合,能经受高压高温;对温度、吸力、应力、应变既能较好地控制,也能较准确地量测;体变、排水、气压量测精度高,传压滞后小;数据自动采集处理,应用方便,造价低;能进行控制温度的饱和土与非饱和土试验。利用该设备对陶岔胀土进行了三种应力路径的控制温度的三轴试验,结果表明,温度对该土的变形、强度和土–水特征曲线有较大影响。温控土工三轴试验设备的研制成功为研究土的热力学特性提供了有力工具。     

超声波三轴压缩试验机及其应用

在单轴压缩试验机的基础上研制了一套超声波三轴压缩试验系统,实现了三轴压缩过程中超声波的全程测试。对一组混凝土试样进行了试验研究,采用小波分析对超声波数据进行处理。在频域范围内提出了三个能反映试样中损伤演化的特征量:归一化第一能量峰值、归一化第二能量峰值、第一能量峰值对应的尺度。本文为研究损伤本构关系提供了新的设备,提出的三个特征量能够反映材料内部结构的变化,特别是第三个特征量具有较强的规律性,可以作为描述材料结构变化的损伤变量。     

超深三轴水泥土搅拌桩技术及在深基坑工程中的应用

随着沿海软土地区深基坑工程的发展,深度超过50m的超深三轴水泥土搅拌桩技术成为深层承压水控制的有效措施。通过工程实例介绍了超深三轴水泥土搅拌桩技术及其在深基坑工程中的应用情况。阐述了超深三轴水泥土搅拌桩的施工工艺、施工要点和质量控制措施,结合上海和天津地区的超深三轴搅拌桩的工程实例进行了说明,验证了超深三轴水泥土搅拌桩技术的可行性和可靠性。     

A simple method for combining fire and structural models and its application to fire safety evaluation

To consider the actual fire characteristics in the fire response analysis of building structures and to simplify the complex relationship between the fire analysis model and the structural finite element analysis model, a spatio-temporal model of the fire temperature and heat flux boundary for heat conduction analysis is developed. The proposed model adopts a two-way orthogonal polynomial approach for fitting the discrete data from the fire simulation and obtains continuous spatial polynomial equations. It is shown to be accurate for capturing the distributions of temperature and heat flux that are required for a heat conduction analysis and a thermal mechanical coupling analysis. Finally, the model is implemented through user-subroutines UTEMP and DFLUX in ABAQUS, and it is applied to a new archive in Beijing. The results show that this method may be used to combine fire simulation and structural analysis for the safety evaluation of structures under fire.     

浅谈节能砌块夹芯复合墙的推广及应用

简要介绍了节能砌块建筑体系的特点及设计施工中的要点,并对三种结构体系进行了经济对比分析,说明了使用该体系具有较好的经济效益,具有十分广阔的推广应用前景。     

机器人感知技术及其简单应用研究

环境感知、运动控制、交互识别是机器人产业发展核心技术模块,其中感知是机器人运动、交互识别前提条件,一旦机器人失去感知能力,将无法帮助人们完成具体工作任务,使"感知+运控+交互"技术核心发展体系相互割裂,影响机器人产业综合发展成效,感知技术重要性随之凸显。文章通过探析机器人感知技术及其简单应用方略,推动机器人产业良性发展。     

A simple method for designation of urban ventilation corridors and its application to urban heat island analysis

This paper describes urban wind ventilation mapping, using the concept of “building frontal area index”, and uses the Kowloon peninsula of Hong Kong as an example of a dense, sub-tropical urban environment where ventilation is critical for human health. The frontal area index is calculated for uniform 100 m grid cells, based on three dimensional buildings in each cell, for eight different wind directions. The frontal area index is then correlated with a land use map, and the results indicate that high density commercial and industrial areas with large building footprints had higher values than other urban land use types. Using the map of frontal area index, the main ventilation pathways across the urban area are located using least cost path analysis in a raster GIS. Field measurements of urban winds confirmed the significance and functionality of these modelled ventilation paths. Comparison of the pathways with a map of the urban heat island suggests that ventilation is a key parameter in mitigating heat island formation in the study area. Planning and environmental authorities may use the derived frontal area index and ventilation maps as objective measures of environmental quality within a city, especially when temperatures in the inner city are a major concern.     

A simple analytical approach to choice

A simple analytical method is described that can be used to assist the decision process in making a choice between a number of options. This method is carried out in two stages. It is an ideal tool to use interactively on a group basis involving the team that is participating in the selection process. Ideally two sheets of a flip chart or a computer spreadsheet can be used to manipulate and collect the results. The first stage is selection criterion ranking and the second stage is candidate item ranking. After the second stage the weighted results are analysed     

Comparison of sand liquefaction in cyclic triaxial and simple shear tests

The liquefaction resistance and correction factors K_σ and K_α of Nakdong River sand obtained from cyclic triaxial (CTX) tests were compared with those determined by cyclic simple shear (CSS) tests to ascertain the importance of the reduction factor C_r and correction factors K_σ and K_α in liquefaction evaluations, especially in view of the lack of comparative liquefaction assessments based on different laboratory test apparatuses. All samples used for the comparisons were obtained from the same type of sand by using similar preparation methods and they were subjected to similar stress states to minimize the number of factors influencing the comparison results; moreover, the apparatuses used in the two tests were manufactured by the same company and all tests were conducted by a single operator. It was found that the liquefaction resistance in CTX tests was always greater than that in CSS tests. Furthermore, C_r varied from 0.63 to 0.36, and it depended on the relative density D_r and initial static shear ratio α. K_σ, which increased with the normal effective stress σ′_nc in CTX tests, was identical to K_σ observed in CSS tests when α was increased up to 0.1. By contrast, K_α in the CSS tests was 58%–97% of K_α measured in the CTX tests, and it depended on the combined effect of D_r, σ′_nc, and α. The relationship between K_α and α in both CTX and CSS tests was well represented by a parabolic function. Moreover, the differences in K_α values between the CTX and CSS tests were also found to be a parabolic function of α. This information can be used for converting CTX (or CSS) values into equivalent CSS (or CTX) values.     

温控非饱和土三轴试验装置的研制及其应用

高放核废物地质处置、地热资源开采与贮存以及城市地下供热管道设计等现代岩土工程的建设都需要考虑温度的影响，使得温度对天然非饱和土体基本性质影响的研究成为土力学的重要课题之一。为了研究非饱和土水力和力学性质受温度影响的规律，需要研制新的温控试验装置，以便为这种研究提供工具和手段。基于对既有非饱和土静三轴仪的改造，研制了一种温控非饱和土三轴试验装置，通过将所研制的温控压力室与非饱和土三轴试验系统的有机结合，实现了试验过程中对温度控制及量测的目的。利用该试验装置，对不同温度下非饱和土土水特征曲线进行了测定，所得结果与现有理论结果相吻合。