首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 46 毫秒
1.

This paper offers a new method for the definition of geotechnical sectors in open pit mines based on multivariate cluster analysis. A geological-geotechnical data set of a manganese open pit mine was used to demonstrate the methodology. The data set consists of a survey of geological and geotechnical parameters of the rock mass, measured directly in several points of the mine, structured initially in twenty-eight variables. After the preprocessing of the data set, the clustering technique was applied using the k-Prototype algorithm. The squared Euclidean distance was used to quantify the proximity between numerical variables, and the Jaccard's coefficient of similarity was used to quantify the proximity between the nominal variables. The different cluster results obtained were validated by the multivariate analysis of variance. The identification of cluster structures was achieved by plotting them on the mine map for spatial visualization and definition of geotechnical sectors. These sectors are spatially contiguous and relatively homogeneous regarding their geological–geotechnical properties, indicated by a high density of points of the same group. It was possible to observe a great adherence of the proposed sectors to the mine geology, demonstrating the practical representativeness of the clustering results and the proposed sectors.

  相似文献   

2.
Engineering geology, like geotechnical engineering, is a new scientific subject in Denmark. Experience in the period since 1924 is laid down in the Danish Code of Practice for Foundation Engineering, which states that the geological conditions establish the foundation class and must be determined as early as possible during the soil investigations by experienced geologists and engineers. The consequences are illustrated by some examples from geotechnical investigations performed at the Danish Geotechnical Institute:
• The economic foundation of a small wooden building on the brink of a postglacial lake and fiord basin at Vedbæk.
• The deep excavation for and foundation of a huge commercial center at Lyngby situated in the middle of a tunnel valley with more than 12 m late- and postglacial organic deposits, based on design and control in the high foundation class.
• The engineering geological modelling of the Quaternary development in the Danish North Sea. Applied geology plays an increasing part in geotechnical engineering as a prerequisite for economic and safe technical solutions. The future use of geological and geotechnical data bases will bring Quaternary geological knowledge into focus.  相似文献   

3.
The results of geotechnical explorations, engineering geological investigation (including laboratory and in situ tests) and field observations have been used, along with borehole logging charts, to obtain the rock mass geotechnical data. Based on the data, the rock mass along the Sabzkuh water conveyance tunnel route was classified by rock mass rating (RMR), Q-system (Q), rock mass index (RMi) and geological strength index (GSI) (3 methods). A new series of correlations were established between the systems based on the data collected from the study area. These relationships were then compared with those reported in the literature, and two new relations were recommended. The classifications were utilized to calculate mechanical properties (rock mass strength and deformation modulus) of the rock mass along the tunnel according to available empirical relations, and to distinguish the upper-bound and lower-bound relations.  相似文献   

4.
 A site specific evaluation of geological barriers is required for landfills and waste repositories. The waste-repository-rock system has to be taken into consideration for this. Since the geotechnical barrier in conjunction with geological barriers contributes considerably to long-term isolation of the harmful substances from the biosphere, it is absolutely necessary to use engineering geology and hydrogeological methods for a quantitative assessment of the barrier effect of the host rock and the geological environment. For a waste disposal mine, the load-bearing capacity of the rock, the protective properties of the surrounding rock formations and the geological stability of the area are important factors in a safety analysis, of which the geotechnical stability analysis is an important part. Such an analysis comprises an engineering geological study of the site, laboratory and in situ experiments and model calculations, long-term monitoring, and special geological and geochemical investigations. Existing geomechanical modelling techniques provide a useful tool to perform barrier integrity calculations and to design an underground disposal mine. As an example, the barrier performance of the rock salt of the Gorleben salt dome is demonstrated using various safety indicators. Received: 3 January 1997 · Accepted: 29 January 1997  相似文献   

5.
This study aims to establish new correlations to assess uniaxial compressive strength (UCS) of northern Algeria sedimentary rocks. This estimation is based on the measurements of density, porosity, and Schmidt hammer hardness. To achieve this goal, a geological and geotechnical characterization campaign was conducted on 19 types of sandstone and carbonate rocks which have been collected from different geological areas of the Maghrebides chain. Petrographic analyses were conducted to identify the geological characteristics of each kind of rock. Subsequently, physico-mechanical tests (i.e., density, porosity, hardness, and uniaxial compressive strength) were carried out for all the sampled rocks. The results were then used to develop correlations between UCS values and the other parameter values determined. Finally, the UCS predictive equations which have the best predictive powers (coefficient of determination R 2 of 0.75 to 0.94) were discussed taking into account the geological specificities of the rocks, and then compared to similar studies developed by other authors in different areas of the world.  相似文献   

6.
ABSTRACT

A fact that is generally overlooked in many geotechnical uncertainty analyses is that input data of the model may be correlated. While this correlation may influence the system response, epistemic uncertainties i.e. lack of knowledge of this correlation appears as a risk factor. This paper discusses how a negative correlation between cohesion (c’) and friction angle (Ø’) with their associated uncertainties can influence both the bearing resistance of a shallow strip foundation footing and the estimation of its safety. A probabilistic approach that considers both the negative correlation and the uncertainty is used in this work as a reference. This method is compared to Eurocode 7 variants that do not for the correlation. These variants, resistance and material factoring methods appears to be more or less conservative depending on the negative correlation degree between (c’–Ø), their associated uncertainties and soil configurations. Finally, the proposed probabilistic comparison shows that the material factoring method is more conservative than the resistance one.  相似文献   

7.
The city of Split has been developing continuously since the construction of the Diocletian Palace (287–305) to the present time. Detailed engineering geological investigations, with the recorded documents, have been performed since 1970. Further development and expansion of the city require an urban engineering geological map to be developed as a main prerequisite for the geotechnical and seismic zonation. In this paper a review of engineering geological conditions at the area of Split City (cca 25 km2) is given. Those conditions are interpreted on the basis of available data from geotechnical reports (about stratigraphical units, their lithological composition and physical and mechanical properties) and limited field survey. Zones with different ground conditions regarding rock properties are delineated in the form of lithological complex, engineering geological mapping units for medium-scale maps. The area of the city of Split, built of foraminifera limestones (E1,2), clayey glauconitic limestones (E21,2 E_{2}^{1,2} ), and flysch sediments (E2,3), is divided into five lithological complexes, which presents unique combination of individual lithological type for which it is possible to indicate general behavior of the whole. The paper also provides short review of other environmental conditions (active geomorphological processes, hydrological and hydrogeological conditions, as well as seismic conditions), which are intended as a guide to the sort of environmental data that could be collected by more detailed studies during the course of the zoning process.  相似文献   

8.
M. Rasouli   《Engineering Geology》2009,108(3-4):208-224
In this paper a detailed engineering geological assessment of rock masses and support design studies at Garmi Chay dam site, has been carried out. This project is located in the northwest of Iran and will be used for flow control and water storage. The diversion tunnel of the dam has a diameter of 5.5 m and a length of 420 m and will be driven in slightly to highly weathered micaschist and trachy andesite rock units. The geological studies include field and laboratory investigations that based on the results; for more exact investigation, tunnel alignment was divided into three geotechnical zones. These zones consist mainly of highly weathered gray micaschists, dark red trachy andesites and slightly weathered gray micaschists, respectively. Then, for every zone, support capacity of rock masses was evaluated by means of empirical and numerical methods. The rock mass classification systems (RMR, Q, GSI, RSR, SRC and RMi), the convergence–confinement method and a 2D finite element computer software, Phase2 were used for empirical and numerical method, respectively. According to the results acquired from these methods some stability problems were expected in the tunnel especially in highly weathered micaschist zone, so that in practice two big collapses occurred. Because of high weathering, low constants of rock masses and their soil-like behavior, the stability analysis by analytical method does not give illogical results in lightly weathered micaschist zone. The support system, suggested by empirical method, was applied and its performance was evaluated by means of numerical modeling. After installation the support suggested by Phase2 program, the thickness of plastic zone and deformations around the tunnel decreased significantly. Consequently the agreement of these methods with each other was resulted and using combination of them was recommended for more reliable support design.  相似文献   

9.
ABSTRACT

A core principle of geotechnical engineering practice is the need to exercise judgement in evaluating soil and site conditions and in performing analyses. The requirement for considering judgement applies equally to performing deterministic or probabilistic analyses. In addition, for probabilistic analyses, choices must be made among the possible methods of analysis and the method of characterising variables. Consequently, geotechnical reliability studies inevitably involve significant uncertainties, and judgement is needed to perform reliability analyses and to evaluate the results. Two case histories, briefly described here, show that judgement and experience are essential prerequisites for meaningful assessment of geotechnical reliability.  相似文献   

10.
In this paper, we further elaborate on a methodology dedicated to the modeling of geotechnical data to be used as input in numerical simulation and TBM performance codes. The expression “geotechnical data” refers collectively to the spatial variability and uncertainty exhibited by the boundaries and the mechanical or other parameters of each geological formation filling a prescribed 3D domain. Apart from commercial design and visualization software such as AutoCAD Land Desktop® software and 3D solid modelling and meshing pre-processors, the new tools that are employed in this methodology include relational databases of soil and rock test data, Kriging estimation and simulation methods, and a fast algorithm for forward or backward analysis of TBM logged data. The latter refers to the continuous upgrade of the soil or rock mass geotechnical model during underground construction based on feedback from excavation machines for a continuous reduction of the uncertainty of predictions in unsampled areas. The approach presented here is non-intrusive since it may be used in conjunction with a commercial or any other available numerical tunneling simulation code. The application of these tools is demonstrated in Mas-Blau section of L9 tunnel in Barcelona.  相似文献   

11.
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:

  • 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.

  • 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.

  相似文献   

12.
ABSTRACT

This paper adds to the ongoing discussion on the role of reliability calculations in geotechnical design. It situates design calculations, be it verified by a global factor of safety, partial factors, or reliability-based design (RBD), in a larger context of quality management over the life cycle of the structure. It clarifies that uncertainties amenable to probabilistic treatment typically fall under the category of “known unknowns” where some measured data and/or past experience exist for limited site-specific data to be supplemented by both objective regional data and subjective judgement derived from comparable sites elsewhere. Within this category, reliability is very useful in handling complex real-world information (multivariate correlated data) and information imperfections (scarcity of information or incomplete information). It is also very useful in handling real-world design aspects such as spatial variability that cannot be easily treated using deterministic means. Examples are presented to illustrate how reliability calculations could relieve engineering judgement from the unsuitable task of performance verification in the presence of uncertainties so that the engineer can focus on setting up the right lines of scientific investigation, selecting the appropriate models and parameters for calculations, and verifying the reasonableness of the results.  相似文献   

13.
Existing experience from the design and construction of underground works is of major importance for the improvement of the construction methods and procedures in tunnelling, especially under adverse and complex geological and geotechnical conditions. This experience can be of great value to geotechnical engineers and engineering geologists, if data acquired through the ground investigation, the design and the construction is systematically collected, categorized and stored in a properly structured database that enables a targeted access to it, as well as to proceed to correlations and analysis, based on engineering criteria. Such a database should be carefully designed to “connect” all available data through all the phases of a tunnel project and premises deep knowledge from the geological and geotechnical investigation to the final design and construction. In order to make substantial use of the experience accumulated from the construction of a great number of tunnels, a database named Tunnel Information and Analysis System (TIAS) was developed. The data source for TIAS database was 62 tunnels of the Egnatia Highway in northern Greece, many of which have been constructed under difficult geological conditions in weak rock masses. The data processed by TIAS came from a variety of sources such as geological mapping, boreholes, laboratory and in situ testing, geotechnical classifications, engineering geological behaviour, groundwater, design parameters, information concerning immediate support measures, construction records and cost. The purpose of the system, besides incorporating extended and multi-source data for easy access, is to provide a tool for turning data into usable information for the comparison of anticipated and encountered geological and geotechnical conditions, the evaluation of geotechnical classification and design methods and the relations regarding rock mass conditions and behaviour and immediate support methods and types.  相似文献   

14.
ABSTRACT

Probabilistic methods in geotechnical engineering have received a lot of attention during the last decade and different methodologies are used to capture the inherent variability of soil in different geotechnical engineering problems. In this paper, numerical simulations are conducted to obtain the bearing capacity factor, Nγ, for a purely frictional heterogenous soil where the friction angle is modelled as randomly distributed throughout the domain and the effect of its spatial variability on Nγ is investigated. A finite element method, based on the upper bound limit analysis was combined with random field theory and linear programming to develop a probabilistic analysis. Monte Carlo simulations were performed and the effect of the variability of the friction angle defined by statistical parameters on the bearing capacity factor was investigated. Results show that the mean bearing capacity factor Nγ of a footing on a spatially variable cohesionless soil is generally higher than the deterministic Nγ obtained from a constant mean value. Increasing the heterogeneity of the friction angle by an increase in the coefficient of variation generally increases this deviation. This can be explained by the nonlinearity of the relationship between Nγ and the friction angle.  相似文献   

15.
A broad assessment of the geological, sedimentological, and geotechnical characteristics of the coastal Holocene sediments of Anzali Area (North Iran) was made to provide a useful guide for development, planning, and construction. Based on the sedimentological and geotechnical properties of the sediments, three engineering geological units as Upper Sandy Zone (USZ), Middle Clayey Zone (MCZ), and Lower Sandy Zone (LSZ) were identified and introduced in the form of an engineering geological model. Then the engineering geological characteristics of the units of the model were analyzed and the main engineering geological problems associated with the deposits of each unit were identified. The results showed that USZ has high liquefaction potential, low bearing capacity, settlement susceptibility, and excavation problem; MCZ has low-bearing capacity as well as high settlement susceptibility and excavation problem; and LSZ has good geotechnical properties, then it poses few problems.  相似文献   

16.
ABSTRACT

The robust geotechnical design (RGD) approach which involves optimization to obtain a design that is safe, cost-efficient, and robust in the face of uncertainties, can be computationally challenging for complex geotechnical structures. In this study, the RGD approach has become practical by introducing a response surface as a surrogate to finite element- or finite difference-based computer code that is used for analyzing the system, and developing a fast algorithm for the optimization process. For demonstration purposes, a real-world supported excavation project is designed using this modified RGD approach and it is compared with the one designed by a local expert.  相似文献   

17.
Before construction activities could begin, engineering geological and geotechnical investigations had to be approved in order to establish a map with suitable areas for safe construction. The example used in this study is Tunis City which has complex geology and geomorphology. The risk analysis was based on a large-scale land-suitability map that was prepared using Geographic Information Systems (GIS). The approach used in this study combined physical data with the geotechnical properties of Tunis City. The adopted methodology and analyses were performed to assess the risk of urban expansion and landscape management. Results are presented as a zoning map that shows the suitable area for safe extension of the urban area. The data used and multi-criterion analysis of geotechnical and geological data seems to be useful for similar case studies and the adopted methodology can be used successfully for identifying similar cities for risk assessment.  相似文献   

18.
This paper presents a fuzzy set-based robust geotechnical design (RGD) methodology for the design of shield-driven tunnels. Here, uncertain geotechnical parameters required for analysis of tunnel performance (referred to herein as the structure safety and serviceability performance of tunnel cross section) are represented as fuzzy sets. Given fuzzy input parameters, the performance of a shield-driven tunnel will be uncertain, which is expressed in this study as a fuzzy factor of safety, according to the analysis of vertex method. Then, the fuzzy factor of safety for a given design is used to evaluate the failure probability and design robustness, which are, in turn, employed in the proposed RGD framework. Note that a design is considered robust if the performance of the shield-driven tunnel is insensitive to the variation of its uncertain geotechnical parameters. Within the RGD framework, each candidate design in the design space is analyzed for its safety state (in terms of failure probability), design robustness, and cost. The goal of the RGD of a shield-driven tunnel is to bring the safety state to an acceptable level, while maximizing the robustness and cost efficiency simultaneously. To this end, a multi-objective optimization is performed and a Pareto front is obtained, which provides a trade-off that may be used to select the most preferred design. Through an illustrative case, the effectiveness and significance of this new robust design methodology is demonstrated.  相似文献   

19.
根据峰峰矿区工业及民用建筑的岩土工程特征,以及在岩土工程勘察中所遇到的诸如由地形地貌产生的不良工程地质现象、特殊地质体等问题,认为在岩土工程勘察中,不仅要研究勘察场地的工程地质条件,而且要重视周围地质条件的宏观研究,同时建议建立岩土工程勘察档案数据库,为今后岩土工程勘察成果的使用、以及正确确定勘察手段奠定基础。  相似文献   

20.
Multiple-expert hazard/risk assessments have considerable precedent, particularly in the Yucca Mountain site characterization studies. A certain amount of expert knowledge is needed to interpret the geological data used in a probabilistic data analysis. As may be the situation in science, experts disagree on crucial points. Consequently, lack of consensus in some studies is a sure outcome. In this paper, we present a Bayesian approach to statistical modeling in volcanic hazard assessment for the Yucca Mountain site. Specifically, we show that the expert opinion on the site disruption parameterp is incorporated into the prior distribution, π(p), based on geological information that is available. Moreover, π(p) can combine all available geological information motivated by conflicting but realistic arguments (e.g., simulation, cluster analysis, structural control, ..., etc.). The incorporated uncertainties about the probability of repository disruptionp eventually will be averaged out by taking the expectation over π(p). We use the following priors in the analysis: (1) priors selected for mathematical convenience: Beta (r,s) for (r,s) = (2, 2), (3, 3), (5, 5), (2, 1),(2, 8), (8, 2), and (1, 1);and (2) three priors motivated by expert knowledge. Sensitivity analysis is performed for each prior distribution. Our study concludes that estimated values of hazard based on the priors selected for mathematical simplicity are uniformly higher than those obtained based on the priors motivated by expert knowledge. And, the model using the prior, Beta (8, 2), yields the highest hazard (=2.97 × 10-2 . The minimum hazard is produced by the “three-expert prior” (i.e., values of p are equally likely for p = 10-3, 10-2,and 10-1 . The estimate of the hazard is 1.39 × 10-3, which is only about one order of magnitude smaller than the maximum value. The term, “hazard, ” is defined as the probability of at least one disruption of a repository at the Yucca Mountain site by basaltic volcanism for the next 10,000 years.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号