基于参数化训练模型的边坡强度折减法研究

依托ABAQUS大型有限元程序,以坡体塑性区贯通和关键点位移突变为失稳判据,实现边坡强度折减法的参数化训练模型,计算了一个边坡算例,通过与Bishop极限平衡法计算结果的对比,验证了参数化训练模型的有效性和准确性,最后将研究成果应用于谷竹高速公路某段边坡,对坡体的安全性进行了分析,并提出了相关建议。     

基于强度折减法的岩溶区高填土地基稳定性分析

应用强度折减法对岩溶区高填土地基下溶洞稳定性进行了有限元分析,综合考虑数值计算收敛性和塑性区范围判定溶洞稳定性,可求出溶洞的抗剪安全系数,使溶洞稳定性分析定量化。     

基于GIS的开发强度模型研究——以上海市中心城为例

中国正处在快速城市化阶段,城市建设日新月异.城市高强度开发和铺张式的低密度开发现象并存,合理确定城市开发强度迫在眉睫.文章基于GIS技术和上海市中心城分区规划确定的人口规模、功能布局、用地布局、道路交通设施布局、市政公用设施布局等前提条件建立开发强度模型,为上海市中心城开发强度的科学规划提供参考和依据.     

基于目标规划的施工企业目标成本控制模型

根据施工企业工程项目目标成本的主要构成,用目标规划的方法构建目标成本控制模型并对该模型运用lingo软件计算出结果,从而准确地控制施工企业工程项目的目标成本,提高施工企业的经济效益。     

基于强度折减法的高陡边坡滑坡治理稳定性分析

针对三道庄露天矿观礼台下方发生的高陡边坡滑坡进行了稳定性分析,并论证了滑坡治理工程的效果。在实地勘探、实验室测试的基础上得到岩土体强度参数等数据,建立原始边坡有限元模型,再加入预应力锚索、锚杆、抗滑桩、挡土墙、灌浆浇筑等支护措施,基于强度折减法建立治理后边坡有限元模型,得出数值模拟结果。对比分析了边坡滑坡处理前后安全系数、塑性应变、位移、构件内力。结果表明:原始边坡安全系数为1.175,应变主要集中于边坡外部碎石、块石松散堆积体与内部中风化片岩交界处,滑移带位置浅; 边坡较易发生局部破坏,整体性及稳定性差; 经治理加固后,预应力锚索、抗滑桩等支护结构充分发挥加固作用,将外部松散堆积体与内部中风化片岩有效固定在一起; 边坡整体性提升,安全系数上升至1.452,边坡滑移带整体位置由浅入深,主要位于中风化片岩内,破坏类型转变为不易发生的整体破坏; 三道庄露天矿边坡下方高陡边坡治理工程效果良好,边坡稳定性得到显著改善。     

基于目标孔隙率的天然浮石混凝土强度分布规律研究

以天然浮石混凝土为研究对象,将橡胶颗粒近似为孔隙加入到混凝土中,将橡胶颗粒体积作为目标孔隙率。测试目标孔隙率在0、1.05%、1.13%、1.18%、2.11%、2.26%、2.37%、3.15%、3.39%、3.55%时,0.40、0.42、0.45三种水胶比条件下,天然浮石混凝土抗压强度和劈拉强度。根据强度变化规律,分别对抗压强度和劈拉强度的分布情况进行拟合。结果表明:天然浮石混凝土目标孔隙率与强度之间有良好的相关性,进而建立了天然浮石混凝土目标孔隙率与强度的经验计算式,为天然浮石混凝土孔隙率的研究提供了一定的理论参考。     

基于本体论的建筑信息模型系统的应用研究

本文通过阐述本体论的概念及相关知识,分析建筑信息模型BIM系统在我国建筑过程中的应用现状,找出我国建筑信息模型BIM系统存在的问题,提出解决问题的几点建议,对我国未来建筑业有效的应用BIM具有重要意义。     

石灰石混合材改善高铝水泥后期强度的研究

研究石灰石作为混合材对高铝水泥强度的影响，探讨其水化作用机理．研究结果表明，适量的石灰石混合材不但可以稳定高铝水泥的早期强度，而且可以有效改善高铝水泥后期强度．     

高应力状态砂土界面抗剪强度的试验研究

通过在DRS-1型微机高压直残剪试验系统上所进行的直接剪切试验研究表明高应力作用下砂-砂、混凝土-砂的抗剪峰值强度与正应力、残余强度与正应力之间的关系,符合库伦强度准则(高应力作用下混凝土-砂的剪切特性呈现出软化现象,混凝土-砂的剪切特性呈现出硬化现象.基底对砂土的抗剪峰值强度准则影响较小,但对抗剪残余强度准则影响较大,界面残余抗剪强度准则的选择与法向应力的大小有关,法向应力较低时剪切破坏发生在砂土中,法向应力较高时剪切破坏发生在界面上).     

基于KiK-net强震记录的三维地震动强度非平稳模型研究

地震动强度非平稳特性对结构非线性响应有显著影响,准确描述强度非平稳特性对生成人工地震波有重要意义。该文提出了一种描述三维地震动强度非平稳特性的模型,分别给出了其确定性参数取值和随机参数取值。首先以大量KiK-net强震记录为样本,提取其强度非平稳特性|然后选取地震动强度非平稳模型,并使用遗传算法识别出了模型的参数|最后通过统计回归分析给出了各震级、震中距不同场地类别的三维模型参数取值。结果表明,所得强度非平稳模型能够反映地震动强度非平稳特性的规律,可将其用于结构抗震分析和人工地震动模拟中。     

多模态评价体系的构建——以《大学英语视听说》为例

多媒体教育技术的应用使英语学习从教材到教学方式均呈现出了不可逆转的多模态趋势,大学英语视听说课具有显著的多模态特征,即学习材料的思维性与多样性,学习环境的真实性与丰富性,学习过程的实践性与互动性,这决定了该课程实施多模态评价的可行性和必要性,并在此基础上对大学英语视听说课构建多模态评价体系。     

冷冻和冰鲜处理对新疆高白鲑鱼片理化指标和腐败菌的影响

为研究经不同加工处理后的高白鲑鱼Coregonus peled在低温贮藏过程中品质的变化,以冷冻和冰鲜处理的新疆高白鲑鱼片为研究对象,研究了其经物流运输后在4℃贮藏过程中物理指标(汁液损失率和剪切力)和化学指标[p H、硫代巴比妥酸(TBA)和挥发性盐基氮(TVBN)值]的变化,并建立了基于Baranyi模型的微生物生长动力学曲线,分析了菌落总数及假单胞菌、产硫菌和肠杆菌在贮藏过程中的动态变化。结果表明:冷冻和冰鲜处理的鱼片经物流运输后汁液损失率、TVBN值均随贮藏时间的延长而增加,TVBN值分别在第11天和第13天时超过20 mg/100 g的标准限值,p H值均呈先降低后升高的趋势,剪切力和TBA值在第5~7天时达到最高值;冷冻和冰鲜处理鱼片菌落总数分别在第6.8天和第7.0天时达到货架期限值[7 log(CFU/g)];贮藏初期鱼片的腐败菌以假单胞菌为主,而在贮藏过程中肠杆菌的生长速率高于假单胞菌和产硫菌,成为优势腐败菌,且冷冻处理的鱼片更有利于优势腐败菌的生长繁殖。研究表明,冰鲜处理更有利于新疆高白鲑鱼片的贮藏。     

混凝土强度预测的两种非线性模型比较研究

混凝土的强度的预测是一个复杂的问题,受多种因素的影响.采用两种先进的非线性算法支持向量机与小波支持向量机,建立 了混凝土强度预测的两种非线性预测方法.研究结果表明:两种方法的预测结果与实测结果吻合较好,小波支持向量机的预测精度较支持向量机精度高,在混凝土的强度预测中具有较好的适应性.     

基于流变仪测试超软土强度的试验方法

随着中国港口工程建设与海洋资源开发的快速发展,遇到了许多涉及超软土的工程问题。对这类具有一定流动性的超软土,常规土工测试方法难以有效地测量其强度。引入流体测试中的流变仪,开展了多组超软土试样的强度和流变特性试验研究,在对试验结果深入分析的基础上,系统探讨了转子尺寸、剪切速率增量和转子轴杆摩阻力对测试结果的影响,提出了一种使用流变仪进行超软土强度测试的有效方法。通过与前人测试结果进行对比分析,验证了该仪器和测试方法的可靠性,从而为超软土不排水剪切强度的有效测量提供了新的途径。     

Buckling mode identification of thin-walled members by using cFSM base functions

The objective of this paper is to demonstrate an approximate method whereby eigen buckling modes from a shell finite element method (FEM) analysis of a thin-walled member can be quantified in terms of the fundamental buckling classes, namely, global, distortional, local, or other. The buckling classes are defined using the mechanical definitions employed in the constrained finite strip method (cFSM). The cFSM base vectors are used to approximate an arbitrary FEM buckling mode. The resulting identification and its associated error is investigated, including dependency on FEM discretization, the number of cFSM functions considered, boundary conditions, and loading. The long-term goal of the work is to provide a generalized method for identification of local, distortional, and global buckling modes for arbitrary thin-walled members modeled in general purpose finite element codes.     

Overhanging rock slope by design: An integrated approach using rock mass strength characterisation,large-scale numerical modelling and limit equilibrium methods

Overhanging rock slopes(steeper than 90°) are typically avoided in rock engineering design, particularly where the scale of the slope exceeds the scale of fracturing present in the rock mass. This paper highlights an integrated approach of designing overhanging rock slopes where the relative dimensions of the slope exceed the scale of fracturing and the rock mass failure needs to be considered rather than kinematic release of individual blocks. The key to the method is a simplified limit equilibrium(LE) tool that was used for the support design and analysis of a multi-faceted overhanging rock slope. The overhanging slopes required complex geometries with constantly changing orientations. The overhanging rock varied in height from 30 m to 66 m. Geomechanical modelling combined with discrete fracture network(DFN)representation of the rock mass was used to validate the rock mass strength assumptions and the failure mechanism assumed in the LE model. The advantage of the simplified LE method is that buttress and support design iterations(along with sensitivity analysis of design parameters) can be completed for various cross-sections along the proposed overhanging rock sections in an efficient manner, compared to the more time-intensive, sophisticated methods that were used for the initial validation. The method described presents the development of this design tool and assumptions made for a specific overhanging rock slope design. Other locations will have different geological conditions that can control the potential behaviour of rock slopes, however, the approach presented can be applied as a general guiding design principle for overhanging rock cut slope.     

Avoidance of bleached kraft mill effluent by pre-exposed Coregonus albula L.

The ability of vendace (Coregonus albula L.) to avoid different concentrations of bleached kraft mill effluent (BKME) was studied in the laboratory with fish pre-exposed to BKME for 1 week and non-pre-exposed fish. Pre-exposure to BKME in sublethal concentrations reduced the avoidance of BKME by vendace. Throughout the range of exposure concentrations (0.13–4.50 v/v%), pre-exposed fish tended to be observed less in the clean water than non-pre-exposed fish or even to prefer contaminated water. In field conditions, changes in behaviour might lead to a chain reaction: the fish come into contact with concentrations of BKME lower than the threshold level for avoidance and their threshold level increases gradually due to this exposure, which makes exposure to higher concentrations possible and weakens the ability to return to clean water. Desensitization caused by pre-exposure and long distances between pronounced BKME concentration differences in the field together makes it improbable that the vendace can show avoidance responses in the field. Analyses of the various waste-water samples support the conclusion that the most toxic components in BKME, resin acids and chlorophenols, are of minor importance to the avoidance reaction.     

Evaluation of shear strength of clayey soils by using their liquidity index

 It is well known that overconsolidated clays have higher shear strength than unconsolidated clays. The liquidity index makes possible an evaluation of the consolidation degree of clays. However, there is no empirical information about this relation. In this study, clayey soil samples have been collected from various locations and tested. The tests include the determination of liquidity index and shear strength. Obtained parameters were correlated and regression equations were established among liquidity index and undrained shear strength, presenting high coefficients of correlation (R=–0.93). So, an equation [c_u=e^{(0.026–1.21 IL)}] that makes possible a rough evaluation of the shear strength of clayey soils by using their liquidity index value is an improvement. Received: 10 December 1999 · Accepted: 4 April 2000     

混凝土强度类型和检测方法比较

通过对混凝土简单概述,归纳出混凝土强度类型,介绍了常用的混凝土强度检测方法,并将其作了对比分析,最后给出了提高混凝土强度的措施,为混凝土的推广应用奠定了基础。