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1.
Giuseppe Raspa Massimiliano Moscatelli Francesco Stigliano Antonio Patera Fabrizio Marconi Daiane Folle Roberto Vallone Marco Mancini Gian Paolo Cavinato Salvatore Milli Joo Felipe Coimbra Leite Costa 《Engineering Geology》2008,101(3-4):251-268
We are presenting an attempt to evaluate the spatial variability of geotechnical parameters in the upper Pleistocene–Holocene alluvial deposits of Roma (Italy) by means of multivariate geostatistics.The upper Pleistocene–Holocene alluvial deposits of Roma are sensitive to high levels of geohazard. They occupy a sizable and significant part of the city, being the foundation for many monuments, historical neighborhoods, and archaeological areas, and the main host of the present and future subway lines. We have stored information from more than 2000 geotechnical boreholes crossing the alluvial deposits into a relational database. For the present study, only the boreholes with lithologic/textural interpretation and geotechnical information were selected. The set includes 283 boreholes and 719 samples, which have a set of geotechnical information comprising physical properties and mechanical parameters.Techniques of multivariate statistics and geostatistics were combined and compared to evaluate the estimation methods of the mechanical parameters, with special reference to the drained friction angle from direct shear test (φ′). Principal Component Analysis was applied to the dataset to highlight the relationships between the geotechnical parameters. Through cross-validation analysis, multiple linear regression, kriging, and cokriging were tested as estimators of φ′. Cross-validation demonstrates that the cokriging with granulometries as auxiliary variables is the most suitable method to estimate φ′. In addition to proving that cokriging is a good estimator of φ′, cross-validation demonstrates that input data are coherent and this allows us to use them for estimation of geotechnical parameters, although they come from different laboratories and different vintages.Nevertheless, to get the same good results of cross-validation in estimation, it is necessary for granulometries to be available at grid points. Since this information being not available at all grid points, it is expected that, in the future, textural information can be derived in an indirect way, i.e., from lithologic/textural spatial reconstructions. 相似文献
2.
岩土工程信息化迫切需要加强大数据集成共享和多专业协同合作，BIM技术在工程建设领域的成功经验给我们以启示，可将BIM技术应用于岩土工程信息化建设，但是当前存在的主要问题是地质模型与BIM模型数据标准不统一。为了解决这个问题，提出了地质模型采用BIM数据标准IFC的思路。采用IFC实体扩展及属性集扩展模式，建立了面向三维地质模型的扩展模型IFC-3DGeoMdl。利用已有的IFC对象类型，派生相应的地质物理实体以及地质空间结构实体，给出地质物理实体的空间表达形式；利用IFC中已有的关系类，定义地质物理实体与空间结构实体的关系；进而，基于IFC中的属性表达方式，实现了地质对象的地层信息与物理力学参数等属性的扩展；最后，给出了创建该模型的具体实现过程，并利用实例验证了该模型的实际应用效果。结果表明，采用该模型，可有效实现岩土工程地质模型与BIM结构模型的集成，从而为深化岩土工程的结构设计、施工等提供有效的地质模型信息。 相似文献
3.
The construction of a three-dimensional (3D) geological model to the scale of a city (greater Bordeaux area, France) has been undertaken, using several thousand boreholes and several hundred geotechnical tests on a more limited area. Data from some specific geographical areas have also been analysed for the purposes of professional applications related to geotechnical engineering, urban archaeology and asset management of buried networks. This paper focuses on the geotechnical dimensions, uncertainties and associated hazards. First, a geometrical model of the quaternary layer basis was built to the scale of the city, the variogram of which quantifies and models the anisotropic spatial correlation of this layer. Two specific studies were then made, as described in the following:
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modelling of the stratigraphy, to the scale of the city, in order to assess the depth and extent of the Flandrian formations. The thickness of these formations is directly linked to the staircase terraces of the Garonne river.
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on-site site analysis of an area where an infrastructure has suffered damage, resulting from large differential settlements, owing to its poor geotechnical properties. We show how geostatistical methods applied to in-situ or laboratory parameters can improve knowledge and understanding of the site, and can be useful in improving the settlement predictions which had been initially underestimated.
4.
Cone Penetration Test (CPT) is widely utilized to gain regular geotechnical parameters such as compression modulus, cohesion coefficient and internal friction angle by transformation model in the site investigation. However, it is challenging to obtain simultaneously the unknown coefficients and error of a transformation model, given the intrinsic uncertainty (i.e., spatial variability) of geomaterial and the epistemic uncertainty of geotechnical investigation. A Bayesian approach is therefore proposed calibrating the transformation model based on spatial random field theory. The approach consists of three key elements: (1) three-dimensional anisotropic spatial random field theory; (2) classifications of measurement and error, and the uncertainty propagation diagram of geotechnical investigation; and (3) the unknown coefficients and error calibration of the transformation model given Bayesian inverse modeling method. The massive penetration resistance data from CPT, which is denoted as a spatial random field variable to account for the spatial variability of soil, are classified as type A data. Meanwhile, a few laboratory test data such as the compression modulus are defined as type B data. Based on the above two types of data, the unknown coefficients and error of the transformation model are inversely calibrated with consideration of intrinsic uncertainty of geomaterial, epistemic uncertainties such as measurement errors, prior knowledge uncertainty of transformation model itself, and computing uncertainties of statistical parameters as well as Bayesian method. Baseline studying indicates the proposed approach is applicable to calibrate the transformation model between CPT data and regular geotechnical parameter within spatial random field theory. Next, the calibrated transformation model was compared with classical linear regression in cross-validation, and then it was implemented at three-dimensional site characterization of the background project. 相似文献
5.
The planning stages of mining require comprehensive and detailed analyses. The proper determination of the orebody boundary is one of the most important points to provide optimum model structure and projections. The limits can be determined by different methods based on the site geology. Although some three dimensional (3D) models were proposed for providing detailed information concerning a mine deposit, developing a solid model via a 3D approach is novelty. In other words, surface modeling should be performed for creating a solid model and determining limits of the deposit. In this way, sensible generation of the surface model can be achieved. This study investigated the estimation capability of the polynomial approach, which is a novel spatial interpolation method, for modeling a coal deposit surface. The performance of the proposed model was compared with some conventional methods in the literature. The results showed that the polynomial interpolation method is an effective method to employ for surface modeling of a mine deposit. 相似文献
6.
岩土参数的空间分布特征由于存在取样数据之间自相关和互相关的特性,未知点的岩土参数属性可通过特定的方法内插或外推,经典的数理统计方法难以确定周围的数据样本点以及相应的插值系数。首先介绍地统计学中基于距离加权的普通克里金（ordinary kriging, OK）算法、泛克里金算法（UK）和协克里金算法（CK）。由于基于滑动距离加权的OK算法无法度量局部空间的奇异性,将引入多重分形理论弥补该缺陷。以2010上海世博会的世博轴区域（长525 m,宽80 m）为工程背景,区域内共有42个取土钻孔,以典型的粉质黏土层3个重要的物理力学指标,即黏聚力、内摩擦角和压缩模量验证以上算法。对于岩土参数黏聚力和内摩擦角,预测精度由高至低为多重分形联合模型（MK）、协克里金模型（CK）、泛克里金模型（UK）、普通克里金模型（OK）;对于岩土参数压缩模量,相应的顺序为泛克里金模型和普通克里金模型位置互换。研究结果证明,在岩土参数空间场的分析中,辅助信息有助于提高数据预测精度,并且多重分形联合模型有助于分析空间局部的奇异性。 相似文献
7.
3D Property Modeling of Void Ratio by Cokriging 总被引：2，自引：0，他引：2
Void ratio measures compactness of ground soil in geotechnical engineering. When samples are collected in certain area for mapping void ratios, other relevant types of properties such as water content may be also analyzed. To map the spatial distribution of void ratio in the area based on these types of point, observation data interpolation is often needed. Owing to the variance of sampling density along the horizontal and vertical directions, special consideration is required to handle anisotropy of estimator. 3D property modeling aims at predicting the overall distribution of property values from limited samples, and geostatistical method can he employed naturally here because they help to minimize the mean square error of estimation. To construct 3D property model of void ratio, cokriging was used considering its mutual correlation with water content, which is another important soil parameter. Moreover, K-D tree was adopted to organize the samples to accelerate neighbor query in 3D space during the above modeling process. At last, spatial configuration of void ratio distribution in an engineering body was modeled through 3D visualization, which provides important information for civil engineering purpose. 相似文献
8.
The particulate nature of granular soils can be accurately simulated at a microscale level. However, due to the huge spatial extent of geotechnical systems, a model fully constructed at such a scale is almost impossible with current computing technologies. Hence, continuum-based approaches are considered as the practical scale for modeling the majority of problems. Combining both scales enables benefiting from the advantages of both techniques while trying to overcome their drawbacks. Although a significant number of publications have addressed coupling both scales, only a few provide information regarding implementing the proposed procedures. In this study, an efficient co-simulation framework for conducting multiscale analysis is introduced. The framework is based on integrating existing continuum and micromechanical modeling software packages and therefore benefitting from already existing codes. A computational simulation of a rigid pile in contact with granular soil demonstrating the capabilities of such technique is presented. The near-field zone surrounding the pile is modeled using DEM whereas FEM is utilized to model far-field zones that are not affected by the presence of the pile. Results of conducted simulations resemble those obtained from experimental results. The proposed approach appears to be a very effective and promising tool to model boundary value problems of geotechnical systems. 相似文献
9.
地下环境信息系统是运用岩土工程、地理学、计算机图形学、计算数学等多学科理论和方法，以GIS技术为基础，结合数据库处理、C 语言编程、OpenGL编程技术、三维图像处理技术建立的对地下环境信息进行数据综合管理和分析的大型信息管理系统。结合笔者开发的广东省东深供水改造工程地下环境信息系统特点，阐述了重大工程地下环境信息系统的功能特征：探讨了GIS二次开发的主要技术，包括：SQL Server数据库处理技术、OpenGL三维图形编程技术、C Builder面向对象编程技术、MAPGIS二次开发技术等；建立了地层三维模型，并提出了映射变换和插值技术相结合的地层切剖原理，以及在地层三维显示和分析中实用的径向基函数插值、滑动最小二乘插值、分片Lagrange插值等方法；开发了数字制图与分析、地基基础设计计算与稳定性分析、三维空间分析的主要功能；提出了地面结构景观和地下空间一体化分析的研究方向，并初步实现其分析功能。最后，在东深供水改造工程中进行了成功应用。 相似文献
10.
Abdelaziz El-Shinawi 《Journal of the Geological Society of India》2017,89(3):339-343
This study compare liquid limit values obtained by the Casagrande apparatus, Russian and British drop cone penetrometer. Liquid limit determined for clay samples collected from 10 boreholes at the Cairo-Suez district (north western part of Badr City), Egypt. It is the most important geotechnical parameter used of fine-grained soils. The liquid limits for 40 natural clay samples varying between 27.8 and 69.7%. It is found that the liquid limit determined by the Casagrande apparatus and Russian standard (cone penetrometer) give essentially the same results with a difference of < 5%. It is observed that the values of Casagrande apparatus were generally lower than those obtained by the cone penetrometer with Russian standard. In addition, Casagrande apparatus for some samples, which had liquid limits of more than 60%, give a higher result. The liquid limits determined by the Russian and British standards are not consistent with a difference of < 1%. Besides, the results which determined by the Casagrande apparatus and British standards (BS), provide equivalent values with a difference of < 3%. 相似文献