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1.
详细介绍了基于尿素水解的微生物诱导碳酸钙沉淀技术(MICP)基本原理;系统总结了MICP技术在土体加固、文物保护、混凝土裂缝修复、金属污染土修复和海洋岩土工程等领域的室内和现场试验研究;分析了环境pH值、温度、钙盐种类、加固土体颗粒粒径和灌浆方法等因素对MICP 技术的影响。MICP技术在岩土工程领域具有广阔的应用前景,但该技术在试验及在实际工程应用领域,特别是在海洋岩土工程领域还存在均匀性、环境适应性、耐久性、经济适用性等方面问题,未来需要对这些问题进行深入的探讨和研究。 相似文献
2.
现代土壤铅污染监测的测定方法 总被引：7，自引：0，他引：7
有关土壤铅污染的测定方法有20多种，这些方法根据其工作原理可分为物理法、理化法、化学法．重点分析了磁测法(物理法)和原子吸收法(理化法)的工作原理、特点．认为磁测简便、快速，对样品无破坏，便于实现监测的自动化、连续化，磁性参数可作为土壤中铅含量简单易行的替代指标．但磁测法准确度不如原子吸收法，原子吸收法耗费、耗时，建议将磁测法和原子吸收法结合起来可以既快速又准确地完成大量土壤样品的测定，满足现代土壤监测的要求． 相似文献
3.
岩土体材料大都表现出分形分布,具有自相似性特征或尺度不变性.通过对河北石家庄市世纪花园地基土的粒度分析,运用分形几何学理论,研究了动力加固前后细粒土粒度成分的分形分维特征,探讨了分维特征的工程意义. 相似文献
4.
指数法和双曲线法组合预测单桩极限承载力 总被引：3，自引：0，他引：3
根据水泥搅拌桩静载试验的有限实测数据预测其极限承载力是工程中常用的方法，文章简要介绍了指数和双曲线这两种预测方法。以权重将两种方法的预测值进行组合。通过工程实例的验算，说明组合预测法的有效性和可行性，并对指数法和双曲线法的结果进行比较。 相似文献
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总结BP网络在岩土工程中的应用情况，针对岩土工程的特殊性讨论用BP网络解决岩土工程问题时应注意的一些问题。 相似文献
7.
唐利斌 《福建工程学院学报》2020,(1):53-56
为精准确定灌注桩的沉降,将桩周土体参数看作随机变量,并采用响应面法对桩基可靠度进行研究。由于,与桩沉降相关的多个土体参数之间高阶项可能存在高度相关性,基于高阶正交原理提出了新型非相关响应面法,以克服传统响应面法不考虑高阶参数高阶相关性的难题。结合实际工程计算发现,提出的新型响应面法比传统响应面法得到的值更为保守。可见,如果不考虑参数的高阶相关性,可能导致高估的计算结果。 相似文献
8.
DALE O. JORGENSON 《Journal of Educational Measurement》1970,7(3):175-185
110 Ss who completed Dunnette's Adjective Check List were randomly divided into a developmental sample (N = 58) and a cross-validation sample (N = 52). S s in the developmental sample were divided into two subgroups by means of Ghiselli's d score technique (difference between standard predictor and criterion scores). Three separate item analyses of the responses of S s in three separate sets of high d score and low d score subgroups yielded three scales: (a) a univariate predictability scale for assessing predictive accuracy from one variable; (b) a moderator scale for determining which of two predictors would be more accurate for an S ; (c) a multivariate predictability scale for assessing predictive accuracy from two predictor variables. The results seem to support the general hypothesis that it is possible to use a performance on a moderator or predictability scale to select a subgroup of S s for whom correspondence between the predictor(s) and criterion is much greater than that of a subgroup whose scores on the moderator indicate a lesser degree of correspondence. All three scales held up in cross-validation. 相似文献
9.
根据对西潼高速公路改扩建工程某桥桥头回填路基的加固处理,分析土工格栅加固方法处理＂桥头跳车＂的可行性。经过实验测定的数据对比分析,土工格栅加固方法效果明显,可以应用于新建高速公路的路基加固工程。 相似文献
10.
Jin CHENG ;Gui-fang DUAN ;Zhen-yu LIU ;Xiao-gang LI ;Yi-xiong FENG ;Xiao-hai CHEN 《浙江大学学报(A卷英文版)》2014,(10):774-788
研究目的：为改善实际工程结构在不确定性条件下的多性能指标,提供一种高效的区间多目标优化方法。创新要点：建立一个目标和约束均为区间不确定性参数函数的区间约束多目标优化模型,提出并实现基于径向基函数、区间分析和非支配排序遗传算法（NSGA-II）的区间多目标优化算法。研究方法：首先,利用区间序关系将每个区间目标转换为同时优化其中点和半径的确定性双目标,利用区间可能度法将区间约束转换为确定性约束,并在此基础上,利用加权法和罚函数法将每个区间目标的约束优化问题转换为相应的无约束优化问题;然后,利用拉丁超立方实验设计和有限元分析构建预测各待优化结构性能指标值的径向基函数;最后,将径向基函数、区间分析法与NSGA-II相结合,快速求出转换后确定性无约束多目标优化问题的所有Pareto最优解,并通过考虑材料不确定性的高速压力机滑块机构设计实例验证该方法的有效性。重要结论：目标和约束均为不确定性参数函数的区间多目标优化模型能有效反映实际工程中同时改善结构多性能指标的需求。基于径向基函数、区间分析和NSGA-II相结合的区间多目标优化算法将传统区间优化模型求解中的嵌套优化过程简化为单层遗传优化过程,大大提高了求解效率,并可获得多目标优化问题的所有Pareto最优解。 相似文献
11.
The crucial point in calibrating soil water content using the technology of time domain reflectometry (TDR) is to establish the relationship between the apparent dielectric constant and the water content. Based on a database, which included 45 kinds of soil samples and 418 data points from our own test data and relevant literature, an empirical calibration equation is proposed. Additionally, the influence of soil type, dry density of soil, compaction energy, pore fluid conductivity, and temperature on the calculated result for water content was also analyzed. Results show that the equation can offer an error of ±0.05 g/g for most soils encountered in geotechnical engineering. However, the estimation error given by the empirical equation becomes significant for soils with dry density less than 1.3 g/cm3, so the equation was modified to consider the influence of dry density. Both of the empirical equations can be used to test gravimetric water content using the TDR method conveniently and efficiently without calibration. 相似文献
12.
Susan Kontos Karen Diamond 《International Journal of Disability, Development & Education》2002,49(4):337-351
Comparable scales to measure quality of early intervention services for infants and toddlers as perceived by parents and service providers were developed based on the Recommended Practices in Early Intervention. Each scale consisted of four subscales focusing on: home-based therapies/instruction, centre-based therapies/instruction, medical/ health services, and service coordination. The scales were administered to 209 parents and 177 of their service providers. A sample of 24 parents completed the instrument twice during a two-week interval to assess test-retest reliability of the parent scale. Test-retest reliability for the parent scale was .785. Validity of the scale was assessed by examining the correlation of parent and provider perceptions of quality with family demographic and early intervention service characteristics. Parents' perceptions of quality were related to family centredness of services. Neither parents' nor providers' perceptions of quality were related to family socioeconomic status. Problems and prospects for measuring quality of early intervention services are discussed. 相似文献
13.
彭天祥 《杨凌职业技术学院学报》2009,8(4):64-69
静力触探技术经过70余年的发展及日趋完善,其操作简单,智能化程度高,是岩土工程勘察常用的原位测试手段之一。静力触探基本原理就是通过探头传感器实现一系列量的转化,并由仪器记录下来,达到测定土强度和其它指标之目的。本文一方面重点论述了静力触探技术在黄土地区勘察中的应用：根据地区黄土地层特点和经验建立了确定地基土承载力的经验公式及其它有关力学参数;详细地论述了如何依据静力触探参数判别土的类别、划分地层界线、确定地下水位埋深和地下洞穴等。特别是依据静力触探参数和曲线形态判别地下洞穴和确定地下水位是本领域的创新和发展。 相似文献
14.
《工程爆破》课程教学方法及教学效果探讨 总被引：1，自引：0，他引：1
《工程爆破》是西南石油大学土木工程（岩土工程）专业学生的一门任选课。以2007级土木工程（岩体工程方向）班为例,在该课程教学过程中采用理论教学与实践教学相结合、板书与多媒体教学相结合以及专业教育与爱国主义教育相结合的＂三结合＂教学方法,考试总评成绩表明该教学方法所反映的教学效果良好,达到了该课程大纲对该专业学生的要求。 相似文献
15.
对宜春地区不同地块不同深度的几种典型原始土样(非扰动)进行了关于土体定名实验研究,并在此基础上对这几种土样进行了精确的工程分类。本次实验选取了宜春不同地块不同深度的原始土样,首先对这几种土样进行密度测量和孔隙率测量的实验。为了获得精确的实验结果,在尽量不扰动土样的基础上,对每一种土样进行平行测定,最终得出它们不同的密度类别与孔隙率,通过查找与对比各类土的密度理论值,根据孔隙比与孔隙率的数学关系,换算出相应的孔隙比,进而对上述原始土样进行定名与工程分类。通过研究,进一步判断出宜春地区典型土体的物理特性和力学性质,进而为该地区正在进行的棚户区改造项目建设所做的地基处理、基坑开挖与支护、边坡防护支护等提供必要而有意义的理论依据,也达到了科研服务地方经济建设的目的。 相似文献
16.
受堆载超载影响下的桩基性状分析研究 总被引：5，自引：0，他引：5
地面大面积堆载超载常常使地基软弱土体产生侧向变形，从而挤压邻近桩基，因而对桩基上部的构筑物不利。将桩体等效成板桩，用梁单元模拟，以一现场试验为依据，章采用平面有限元分析了堆载超载影响下的相邻桩基性状。 相似文献
17.
This study examined the stability of the Kaufman Assessment Battery for Children (K-ABC) for a sample of at-risk preschool children. Over a 9-month time interval, the stability coefficients (corrected for restriction in range) for the global scales of the K-ABC ranged from .78 to .88. The stability coefficients (corrected for restriction in range) for the K-ABC subtests ranged from .65 to .79. It was concluded that scores on the K-ABC for at-risk preschool children display adequate stability, but that the Simultaneous scale appears to be more amenable to change than either the Sequential or Achievement scales. 相似文献
18.
Patricia Sanderson 《Educational research; a review for teachers and all concerned with progress in education》2013,55(1):91-99
This research report describes the development of dance attitude scales which were 'grounded' in the opinions of groups of 11-16-year-old pupils in six schools throughout England. Factor analyses involving an initial sample of 368 male and female secondary school pupils produced four embryonic scales which were then tested with a sample of 1,668 adolescents. Satisfactory internal reliability coefficients were achieved and scale intercorrelations provided evidence of the scales as distinct measures. Further analyses undertaken to test validity employing data from the larger sample indicated that two of the proposed scales, Ballet and Male Dancers, may be valid measures of attitude, although less confidence can be placed in the third and fourth scales. Suggestions are made for the development and application of the inventory. 相似文献
19.
Derek C. Briggs 《Journal of Educational Measurement》2013,50(2):204-226
A vertical score scale is needed to measure growth across multiple tests in terms of absolute changes in magnitude. Since the warrant for subsequent growth interpretations depends upon the assumption that the scale has interval properties, the validation of a vertical scale would seem to require methods for distinguishing interval scales from ordinal scales. In taking up this issue, two different perspectives on educational measurement are contrasted: a metaphorical perspective and a classical perspective. Although the metaphorical perspective is more predominant, at present it provides no objective methods whereby the properties of a vertical scale can be validated. In contrast, when taking a classical perspective, the axioms of additive conjoint measurement can be used to test the hypothesis that the latent variable underlying a vertical scale is quantitative (supporting ratio or interval properties) rather than merely qualitative (supporting ordinal or nominal properties). The application of such an approach is illustrated with both a hypothetical example and by drawing upon recent research that has been conducted on the Lexile scale for reading comprehension. 相似文献
20.
Tenko Raykov George A. Marcoulides Siegfried Gabler 《Structural equation modeling》2017,24(5):755-767
In repeated measure studies with unidimensional scales, measurement invariance, and specificity stability over time, the specificity variance in each instrument component can be identified. This article describes for that setting an improved point and interval estimation procedure for the maximal reliability coefficient associated with a given set of homogeneous measures. The method is developed within the framework of latent variable modeling and can also be readily used in longitudinal studies for improved point and interval estimation of individual measure reliability and scale reliability at each assessment occasion. The procedure is based on empirically testable conditions and is illustrated with an example. 相似文献