Evaluation of liquefaction potential using neural-networks and CPT results

In this research, a reliable Cone Penetration Test data set was gathered with a wide range of parameters. This data was incorporated in a Neural-Networks computer software called STATISTICA Neural-Networks. The back propagation algorithm with a multilayer perceptron network is utilized to analyze the liquefaction occurrence in different sites. In this study, different sets of effective parameters for the neural-network analyses are selected such that to reduce the noise and to obtain more accurate results.Considering the relative importance of effective parameters in liquefaction assessment, it is indicated that σ₀, σ′₀ together play a more important role than what previously was assumed and hence the relative importance of the q_c and seismic parameters are decreased compared with the previous works. The results presented here have more accuracy than previous works while at the same time, the range of the parameters used in this study is much wider than what was previously used. This range of parameters makes the proposed method applicable for practical purposes.     

Empirical correlations of soil parameters based on Cone Penetration Tests (CPT) for Greek soils

This study presents the results of Cone Penetration Tests (CPT) and estimated correlations with the results of other in-situ tests (standard penetration test, cross-hole, seismocone) and laboratory tests (classification and undrained shear strength tests). These tests cover nearly all types of penetrable soils in Greece and, together with the formulation of empirical correlations, complement and improve on previous studies due to the significant number of CPT measurements.     

Creating a GIS application for retail centers in Jeddah city

The aim of this paper is to identify the role of geographical information systems (GIS) in supporting retail planners in monitoring and analyzing retail development and growth. At first, a review about retail planning and its relevant issues is made. Second, GIS is defined together with its applications in retail planning. The third part discusses the created GIS application that is designed for two retail centers in Jeddah city, Saudi Arabia. This application is created to help planners in defining the distribution of retail demand, describing customers profile, analyzing trade areas and modeling retail flows. Two useful models have been produced by this study. One is called market penetration and the other is based on spatial interaction technique. The former is created to examine retail center catchment area, while the latter is used to model the interaction between demand areas and retail centers.     

Evaluation of soil liquefaction in the Chi-Chi, Taiwan earthquake using CPT

During the 1999 Chi-Chi, Taiwan earthquake, many sand boiling phenomena were observed in central Taiwan, which caused severe ground settlement and structure damages. According to the installed accelerograms, the peak ground surface horizontal accelerations in the liquefaction-affected areas range from 774.42 to 121.3 gal. The writers carried out an extensive investigation of soil liquefaction in this earthquake. In this paper, we present results of the CPT exploration and post-earthquake liquefaction analysis. Two hundred and seventy five (275) cone penetration test data were collected from the liquefaction-affected areas, and 46 liquefaction case histories and 88 non-liquefaction case histories were derived that can be used to evaluate the accuracy of existing liquefaction evaluation models. In addition, the strength of the liquefied soils after earthquake and the implication of its liquefaction potential in the future event are discussed.     

砂土液化判别方法可靠性评价

在进行液化评价简化法与规范液化判别方法对比基础上，利用液化概率的对数回归方程，讨论了规范液化判别方法的可靠性。研究结果表明，我国规范液化判别方法其液化概率变动较大，对于烈度 Ⅶ 度，规范法的液化概率在0.17～0.42间，小于简化法概率0.36～0.43，偏保守。对于烈度 Ⅷ 度和 Ⅸ 度近地表场地，规范法的液化概率高达0.65～0.70，远远高于简化法的液化概率，安全裕度不够。对于含粘粒土质液化评价，规范方法的液化概率总体上都较简化法高，特别是烈度Ⅷ度高粘粒含量其液化概率为0.9。     

基于数据融合的侧扫声纳图像预处理

论述了基于数据融合的侧扫声纳图像处理的特殊过程。根据现代侧扫声纳系统的特点，提出了利用声线跟踪法进行斜距改正，同时对目标阴影区进行了处理；对文献[1]的灰度不均衡的改正算法进行了改进。利用小波变换检测出灰度突变区，根据剔除突变区后计算的灰度改正系数进行航向上的灰度改正，并用模拟数据和实际数据进行了验证；鉴于波束展宽效应对远场目标造成的拖尾效应，论述了对拖尾效应使用的去卷积的改正算法。     

Estimating severity of liquefaction-induced damage near foundation

An empirical procedure for estimating the severity of liquefaction-induced ground damage at or near foundations of existing buildings is established. The procedure is based on an examination of 30 case histories from recent earthquakes. The data for these case histories consist of observations of the damage that resulted from liquefaction, and the subsurface soil conditions as revealed by cone penetration tests. These field observations are used to classify these cases into one of three damaging effect categories, ‘no damage’, ‘minor to moderate damage’, and ‘major damage’. The potential for liquefaction-induced ground failure at each site is calculated and expressed as the probability of ground failure. The relationship between the probability of ground failure and the damage class is established, which allows for the evaluation of the severity of liquefaction-induced ground damage at or near foundations. The procedure presented herein represents a significant attempt to address the issue of liquefaction effect. Caution must be exercised, however, when using the proposed model and procedure for estimating liquefaction damage severity, because they are developed based on limited number of case histories.     

沙漠砂抗剪强度指标与原位测试指标关系研究

为了在沙漠地基勘察中推广应用静力触探技术,在控制相对密度和含水量的条件下,进行了一系列室内大、中型槽原位测试模拟试验及相关土工试验,取得了塔克拉玛干沙漠砂静力触探指标 ,标准贯入试验锤击数 和抗剪强度指标 的一系列有效数对,并进行了线性回归,建立了 - 和N- 之间的相关关系,且论证了二者之间的协调性。给出的公式为沙漠油田地面工程勘察积累了经验。     

九江市网纹红土标准贯入击数与力学参数关系分析

针对九江市网纹红土层标准贯入试验实测锤击数与试验孔深、土的压缩模量、抗剪强度关系之间进行了相关性分析。结果表明：网纹红土标准贯入击数与试验孔深为正显著线性相关关系,与土的压缩模量为正弱线性相关关系,与抗剪强度为正弱线性相关关系。分析成果对在九江市开展岩土工程勘察活动具有很好的指导和借鉴意义。     

恒速压汞技术定量评价低渗透砂岩孔喉结构差异性

针对常规压汞不能准确确定储层孔隙与喉道的弊端,利用恒速压汞技术对鄂尔多斯盆地低渗透砂岩样品孔喉结构的差异性进行了定量评价.结果表明,渗透率越小的岩心,喉道分布越集中,随着渗透率的增大,大喉道分布逐渐增多,喉道分布范围也更加宽泛,主喉道半径随之增大,但较大喉道对低渗透砂岩储层的开采效果具有双重影响;渗透率小于0.5×10...