Engineering Geological Database Research Articles

Predictive model for shear wave velocity of gravelly soil and its application to liquefaction triggering assessment

Several studies have established empirical correlations between shear wave velocity (Vs) and standard penetration test blow count (SPT-N) for engineering use. However, these empirical correlations cannot be applied to gravel-rich soils since the measured SPT-N is often inflated in gravel. Therefore, an empirical correlation of Vs for gravel is developed in this study using the Engineering Geological Database for the Taiwan Strong Motion Instrumentation Program. The Vs predictive model considers gravel content (GC) and coefficient of uniformity (Cu) in addition to effective vertical stress, void ratio, fines content, plasticity index, and overconsolidation ratio, which have been considered previously. The proposed model indicates that Vs increases with GC and Cu. Moreover, the Vs adjusted for GC can be used with existing Vs -based liquefaction triggering relationships to rationally define the boundary between liquefaction and non-liquefaction case histories with different GCs.

An engineering geological database for managing, planning and protecting intelligent cities: The case of Thessaloniki city in Northern Greece

The challenge in intelligent cities is to recognize the benefits of using big data. The management of big datasets enables efficient data storage and processing to enhance information for the decision-making process. The key aim of this paper is to highlight how geological, engineering geological and geotechnical knowledge can be managed in a well-organized database, which is able to develop various correlations and to present useful information for both the design and construction stages of important projects of civil protection, municipality and technical companies.The present paper demonstrates the implementation of such work in the city of Thessaloniki, northern Greece, where a large amount of geological and geotechnical data for more than 600 boreholes, mainly based on borehole geological information, laboratory testing, geotechnical characterization and in situ field tests collected from fill, Quaternary and Neogene deposits, is stored in a georeferenced database. The presented database, is targeted to the management and processing of geo-engineering datasets for various geotechnical projects but also for the protection against natural hazards. The purpose of the approach, besides incorporating multisource datasets, is to provide a tool to effortlessly and immediately analyze, correlate and display data on maps, tables and diagrams for stakeholders. For this analysis, the present study proposes a geographic information system approach coupling the use of geostatistical techniques along with the cross validation to establish geotechnical zonation maps in order to highlight hazardous areas prone to liquefaction and settlement and to indicate the site's adaptability for different infrastructure projects.In that context, specific value ranges for several physical and mechanical properties are proposed from the assessment and correlation of the information originating from the database and spatial variability, providing geological and geotechnical knowledge in safe urban extensions suitable for construction in the research area environment. However, the key challenge is not only referring to provide each influencing parameter with a quantitative range of values, but also to establish a set of reliable structural and high-precision informative geotechnical models to comprehensively understand the superficial and subsurface conditions of the research area.

PredictingVpand constrained modulus reduction curve based onVsand shear modulus reduction curve in accordance with poroelastic theory

The compression wave velocity (Vp) of sediments plays a key role in seismic wave amplification of vertical motion and is required in site response analysis. However, such information is usually lacking during field exploration (e.g. the surface wave method) because only shear wave velocity (Vs) is obtained. This aim of this study is to predict Vpbased on Vsempirically and theoretically, particularly focusing on saturated conditions. The empirical approach is to establish the Vpcorrelation dependency on Poisson's ratio and Vs, and the theoretical approach is based on poroelastic theory that accounts for the interaction between fluid and soil skeleton. The engineering geological database for the Taiwan strong motion instrumentation program and the Kiban Kyoshin network database in Japan are adopted to establish an empirical model and validate poroelastic theory. The validated poroelastic approach is used to develop a constrained modulus reduction curve dependency on the porosity, Vs, Poisson's ratio and degree of saturation with a shear modulus reduction curve. The proposed approach can be used to develop generic Vpprofiles and constrained modulus reduction curves for the site response to vertical motion given a site-specific Vsprofile.

Investigation of shallow S-wave velocity structure and site response parameters in Taiwan by using high-density microtremor measurements

Site effect is considered a critical component affecting ground motions, and the shallow velocity structure is a primary factor for determining the site effect. The shallow velocity structure should be carefully evaluated to mitigate earthquake hazards. Thus, we use microtremor array measurements as well as the inversion of microtremor horizontal-to-vertical spectral ratios (MHVSRs) to investigate shallow S-wave velocity (Vs) profiles in Taiwan, which is one of the most seismically active areas of the world. On the basis of the diffuse field assumption, Vs profiles can be efficiently inverted. To reduce the nonuniqueness of MHVSR inversion, Vs profiles obtained using microtremor array measurements and from an engineering geological database were adopted as model constraints. Finally, this study included 3587 inverted MHVSR Vs profiles and 65 inverted Vs profiles from microtremor arrays. The results were used to create a detailed updated VS30 map of Taiwan and to map the depth contours of Z1.0; thus, the relationship between VS30 and Z1.0 was determined. We proposed a new parameter, HR, as a proxy for VS30, that is defined as a ratio of the average MHVSR across high- and low-frequency bands. This parameter was correlated to the predominant frequency without subjective selection. Moreover, we constructed a pseudo-three-dimensional shallow Vs model of Taiwan, which describes main shallow structural features and provides complete details for plain areas.

Geothermal potential of the NE extension Warsaw (Poland) metro tunnels

Thermoactive geostructures are considered an economically suitable and environment-friendly solution for heating and cooling buildings. Energy tunnels have gained growing interest in recent years because of the large ground volume involved in heat exchange in comparison to building foundations. Heat exchange is obtained by embedding a circuit of pipes into the precast concrete lining, resulting in a reduction of the initial costs of installation with respect to standard low-enthalpy geothermal solutions. In this paper, thermal activation of the twin tunnels of the II line of Warsaw metro, Poland, is considered with the aim of evaluating the geothermal potential of the line. Thermohydraulic finite-element analyses were performed on a number of representative cross-sections, considering site-specific hydrogeological conditions based on the Engineering Geological Database of the Capital City of Warsaw. Results demonstrate that the thermal activation of the two 1·6 km-long tunnels could exchange up to 5·3 and 5·8 GWh in the heating and cooling seasons, respectively. Furthermore, the influence of the local geological conditions on the exchangeable heat rate was investigated. The results form a basis for a preliminary assessment of the shallow geothermal energy utilisation potential for the design of further extensions of the metro line in Warsaw.

Unified correlation between SPT–N and shear wave velocity for a wide range of soil types considering strain-dependent behavior

The shear wave velocity (Vs) of sediments plays a key role in seismic wave amplification and is required in site response analysis. Such information is usually lacking during field exploration, but standard penetration test blow count (N) is typically available. Therefore, several studies have established empirical correlations between N and Vs for engineering use. However, these empirical correlations significantly vary in terms of model form and are only applicable to specific soil types, such as sand or clay. A unified empirical correlation for a wide range of soil types, which contains several soil properties (e.g., liquid limit and plasticity index (PI)) in addition to the Vs and N of strata, is developed in this study using the Engineering Geological Database for the Taiwan Strong Motion Instrumentation Program. Influences of confining stress, fines content (FC), PI, and soil types on small-strain properties (i.e., Vs) and large-strain measurements (i.e., N) are first evaluated through the developed correlations with these parameters. The unified correlation between Vs and N that is dependent on confining stress, FC, and PI is then proposed through the conditional prediction approach. The model successfully applies to different regions in Taiwan that includes various types of soil deposits and, thus, is potentially used for the other regions.

Research on prediction model of geotechnical parameters based on BP neural network

With the vigorous development of the national economy, the pace and scale of urban construction have been unfolded at an unprecedented speed. A large number of construction projects have made the urban engineering geological exploration activities reach a considerable scale in depth and breadth. The survey results of these projects are very valuable information resources, which not only played an important role in urban planning and construction at that time, but also had high reuse value. Based on BP neural network theory, this paper uses engineering geological database as the research and development platform. Based on the theory of BP neural network and the engineering geological database as the research and development platform, this paper establishes the prediction of geotechnical parameters based on the analysis of the characteristics of geotechnical materials and the distribution of geotechnical sediments and geotechnical parameters. Based on the survey data and specific engineering information, the prediction model of the project was established, and the distribution of the stratum and the relevant geotechnical parameters were predicted. Based on the study of geotechnical properties and BP neural network, a new parameter prediction model is established. Taking the engineering geological database as the platform, using the programming language such as MATLAB, the preliminary research and construction of this prediction system were carried out. The results show that the generalization ability of the prediction model meets the requirements.

Engineering-Geological Data Model - The First Step to Build National Polish Standard for Multilevel Information Management

The efficient geological data management in Poland is necessary to support multilevel decision processes for government and local authorities in case of spatial planning, mineral resources and groundwater supply and the rational use of subsurface. Vast amount of geological information gathered in the digital archives and databases of Polish Geological Survey (PGS) is a basic resource for multi-scale national subsurface management. Data integration is the key factor to allow development of GIS and web tools for decision makers, however the main barrier for efficient geological information management is the heterogeneity of data in the resources of the Polish Geological Survey. Engineering-geological database is the first PGS thematic domain applied in the whole data integration plan. The solutions developed within this area will facilitate creation of procedures and standards for multilevel data management in PGS. Twenty years of experience in delivering digital engineering-geological mapping in 1:10 000 scale and archival geotechnical reports acquisition and digitisation allowed gathering of more than 300 thousands engineering-geological boreholes database as well as set of 10 thematic spatial layers (including foundation conditions map, depth to the first groundwater level, bedrock level, geohazards). Historically, the desktop approach was the source form of the geological-engineering data storage, resulting in multiple non-correlated interbase datasets. The need for creation of domain data model emerged and an object-oriented modelling (UML) scheme has been developed. The aim of the aforementioned development was to merge all datasets in one centralised Oracle server and prepare the unified spatial data structure for efficient web presentation and applications development. The presented approach will be the milestone toward creation of the Polish national standard for engineering-geological information management. The paper presents the approach and methodology of data unification, thematic vocabularies harmonisation, assumptions and results of data modelling as well as process of the integration of domain model with enterprise architecture implemented in PGS. Currently, there is no geological data standard in Poland. Lack of guidelines for borehole and spatial data management results in an increasing data dispersion as well as in growing barrier for multilevel data management and implementation of efficient decision support tools. Building the national geological data standard makes geotechnical information accessible to multiple institutions, universities, administration and research organisations and gather their data in the same, unified digital form according to the presented data model. Such approach is compliant with current digital trends and the idea of Spatial Data Infrastructure. Efficient geological data management is essential to support the sustainable development and the economic growth, as they allow implementation of geological information to assist the idea of Smart Cites, deliver information for Building Information Management (BIM) and support modern spatial planning. The engineering-geological domain data model presented in the paper is a scalable solution. Future implementation of developed procedures on other domains of PGS geological data is possible.

Engineering geological characterization of the Antalya karstic rocks, southern Turkey

This study encompasses engineering geological characterization of the Antalya karstic foundation rocks, particularly tufa, whose mechanical behavior is highly variable. The Antalya tufa rock has no well-developed discontinuity systems. It is variably porous, and is composed of different rock types with variable structures. To reveal the engineering geological parameters and to develop a thorough engineering geological database, which is not available in the literature for the Antalya tufa rock, geological observations, engineering geological site investigations, mineralogical analyses, field (plate load tests) and laboratory geomechanics tests have been performed. The physico-mechanical properties such as porosity, seismic wave velocity, uniaxial compressive strength, Young’s modulus, deformation modulus, tensile strength, cohesion, angle of internal friction and other petrographic characteristics such as organic matter content and rock fabric that are expected to have a significant influence on its behavior were determined. Regression analyses have been performed to obtain relationships between the engineering geological parameters of the Antalya tufa rock. A number of good correlations (R 2 ≥ 0.75) obtained by regression analyses indicated that the Antalya tufa rock types could be differentiated better by using the strength parameters (namely, uniaxial compressive and tensile strength) and the index parameters (namely, unit weight and porosity).

Three-Dimensional Engineering Geology Data Warehouse Constructed by Power Designer

The Three-dimensional engineering geology data warehouse is constructed by Power Desinger16.1, with the theme as the rock and mass availability in urban underground space, and with the source data as the borehole data of engineering Investigation. Use the Model-driven Architecture method, reverse engineer the Access data base, extract existed data model, combine research theme to construct the Star data structure model. And check the SQL script in SQL Server2005, to ensure normal operation. 0 Forewords The traditional transaction-oriented designed engineering geology data base has the function to storage original data from work, to draw of geological section and to provide simple check and analysis, but without the decision support function in view of a subject. The purpose of construction a 3D engineering geological data warehouse is to build a decision support system in view of availability of rock and soil mass in urban underground space. Based on the data extraction, data integration, data cleaning and data transformation, the 3D engineering geological data warehouse could achieve the integrated management of massive geological data and to provide reliable data source for the rock and soil mass utilization system in urban underground space. The main feature of 3D engineering geological data base is subject-oriented, integrated, time-varying, relatively stable, and is magnanimous collection of engineering geological spatial data and attribute data. According to the design pattern of traditional data base, the construction of 3D engineering geological data warehouse can be divided into three stages: concept design model, logic design model and physical design model. But the 3D engineering geological data warehouse exist iterative in the construction process. Currently, there are many CASE tools to help developers quickly achieving the data base design, such as Rational Rose by Rational company, Erwin and Bpwin by CA company, Power Designer by Sybase company, Office Visio by Microsoft company, and Oracle Designer by Oracle company. The paper uses the Powerdesigner16.1 to achieve the logical data model (LDM) and physical data model (PDM).

Site classification and Vs30 estimation of free-field TSMIP stations using the logging data of EGDT

The Engineering Geological Database for TSMIP (EGDT), the Taiwan Strong Motion Instrumentation Program, has been under construction by the National Center for Research on Earthquake Engineering and the Central Weather Bureau in Taiwan since 2000. Site characterization, comprising surface investigations and logging measurements, was carried out throughout the project. We provide a set of specifications and a description to help users understand the subject matter of the database. EGDT contains 469 surveyed stations, 439 of which were drilled and the logging measurements completed. Of these, 385 had logging data reaching at least 30m, and we used these to examine and determine the most accurate extrapolation of Vs30 (the average S-wave velocity of the top 30m of strata) for the other 54 stations with velocity profiles less than 30m. The chosen method assumed that the bottom velocity is identical from the actual depth of the hole to a distance of 30m, that is, the Bottom Constant Velocity (BCV) method. In order to utilize other existing boreholes which have only N values but no velocities in the future, the empirical S-wave velocity equations for seven different regions and the whole of Taiwan were evaluated by a multivariable analysis. Henceforth, for those existing boreholes which have an N profile less than 30m, the S-wave velocity profile can first be calculated by empirical S-wave velocity equations, and then Vs30 can be estimated by reliable extrapolation. Some other studies of site classifications of TSMIP stations were compared with our results to demonstrate the necessity of reclassification. Ultimately, the Vs30 values of the 439 drilled free-field TSMIP stations were derived and the new site classification was achieved according to the Vs30-based provisions of the National Earthquake Hazards Reduction Program.

Comparison of three different methods in investigating shallow shear-wave velocity structures in Ilan, Taiwan

The Central Weather Bureau (CWB) and National Center for Research on Earthquake Engineering (NCREE) launched a project to build an engineering geological database for strong-motion stations in Taiwan in 2000. The project measures shear-wave velocity using the suspension PS-logging method. In this study, we conduct array measurements of microtremors and apply the stress wave propagation method (SWPM) at seven free-field strong-motion stations in Ilan County to estimate shallow shear-wave velocity structures. We focus on the sediment layers of the top 100 m to compare the shear-wave velocity structures of the three different methods. There are some misfits among the results of the three different methods; so we calculate the values of Vs 30, Vs 100 and plot S-wave travel-time curves of these methods for each site to analyze the misfits effectively. This analysis helped us to prove the efficiency of the microtremor array method in investigating shear-wave velocity structures in the shallow subsurface. Moreover, the horizontal-to-vertical ratios of microtremors for each survey point show the existence of divergence at the same site. We considered this as evidence that misfits are caused by the heterogeneous nature of sediments and also due to the nature of the methods as being one-, two- and three-dimensional. Furthermore, the average shear-wave velocity structure of microtremor arrays may be more representative of the whole site.

AN APPROACH TOWARDS DETERMINISTIC LANDSLIDE HAZARD ANALYSIS IN GIS. A CASE STUDY FROM MANIZALES (COLOMBIA)

A one-dimensional deterministic slope stability model (infinite slope model) was used to calculate average safety factors and failure probabilities for the city of Manizales, in central Colombia. An engineering geological data base has been created on the basis of a series of parameter maps (geology, geomorphology, Digital terrain models and slope classes), using logic reasoning in Geographic Information Systems (GIS). A two-dimensional hydrological model was applied to estimate groundwater levels in relation to rainfall events. A simple method for the calculation of horizontal seismic acceleration was used for different earthquake events. To calculate average safety factors a number of scenarios were developed, by combining the effects of groundwater and seismic acceleration with different return periods. A simple method for error propagation was used to calculate the variance of the safety factor, and the probability that it will be less than 1, for each pixel, within a time period of 20 years. The highest probability value of the various scenarios was selected for each pixel, and a final hazard map for translational landslides was constructed. The results presented here are a first approach towards a deterministic landslide hazard analysis using GIS. It has a number of drawbacks, which should be solved in future work.

AN APPROACH TOWARDS DETERMINISTIC LANDSLIDE HAZARD ANALYSIS IN GIS. A CASE STUDY FROM MANIZALES (COLOMBIA)

A one-dimensional deterministic slope stability model (infinite slope model) was used to calculate average safety factors and failure probabilities for the city of Manizales, in central Colombia. An engineering geological data base has been created on the basis of a series of parameter maps (geology, geomorphology, Digital terrain models and slope classes), using logic reasoning in Geographic Information Systems (GIS). A two-dimensional hydrological model was applied to estimate groundwater levels in relation to rainfall events. A simple method for the calculation of horizontal seismic acceleration was used for different earthquake events. To calculate average safety factors a number of scenarios were developed, by combining the effects of groundwater and seismic acceleration with different return periods. A simple method for error propagation was used to calculate the variance of the safety factor, and the probability that it will be less than 1, for each pixel, within a time period of 20 years. The highest probability value of the various scenarios was selected for each pixel, and a final hazard map for translational landslides was constructed. The results presented here are a first approach towards a deterministic landslide hazard analysis using GIS. It has a number of drawbacks, which should be solved in future work.

Ingeo-base, an engineering geological database : Herbschleb, J Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6–10 August 1990, SymposiaP47–53. Publ Rotterdam: A A Balkema, 1990

Ingeo-base, an engineering geological database : Herbschleb, J Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6–10 August 1990, SymposiaP47–53. Publ Rotterdam: A A Balkema, 1990

The use of stochastic models in the assessment of a geological database

Summary The most appropriate method of assessing ground investigation information will depend on the nature of the investigation and the character and quantity of data. There are significant advantages to collecting such data in a quantified form since computer-based databases can then be established, facilitating their rapid assessment. Methods of assessing an engineering geological database are described. Particular attention is paid to the use of stochastic models for analysis, which are applicable to data whose distribution can be described in terms of a random function.