To reveal the roles of pores and fissures in the rock-weakening effect of water, this study used porosity to quantitatively characterize pores and fissures in rocks. Based on the results from mechanical tests on rock specimens with different porosities and degrees of saturation, the combined effects of the porosity and water content on the mechanical properties and deformation behaviour of rocks were investigated. The test results indicated that the rock-weakening effect of water was markedly more significant if the pores and fissures in the rock were highly developed. The test data showed that the ratio of the saturated specimen strength to the dry specimen strength of porous rock can be even lower than 0.1. The least-squares regression method was used to derive the impact of rock porosity on rock-weakening due to the effect of water. Based on the results, a practical engineering method for modifying the mechanical parameters of wet rocks with highly developed pores and fissures was proposed. This method can be used to more accurately calculate the stress-strain state of rocks.
{"title":"Combined effects of the porosity and degree of saturation on the mechanical properties and deformation behaviour of rocks","authors":"Yue Pan, Guang Wu, Liu He, Zhiming Zhao","doi":"10.1144/qjegh2020-074","DOIUrl":"https://doi.org/10.1144/qjegh2020-074","url":null,"abstract":"To reveal the roles of pores and fissures in the rock-weakening effect of water, this study used porosity to quantitatively characterize pores and fissures in rocks. Based on the results from mechanical tests on rock specimens with different porosities and degrees of saturation, the combined effects of the porosity and water content on the mechanical properties and deformation behaviour of rocks were investigated. The test results indicated that the rock-weakening effect of water was markedly more significant if the pores and fissures in the rock were highly developed. The test data showed that the ratio of the saturated specimen strength to the dry specimen strength of porous rock can be even lower than 0.1. The least-squares regression method was used to derive the impact of rock porosity on rock-weakening due to the effect of water. Based on the results, a practical engineering method for modifying the mechanical parameters of wet rocks with highly developed pores and fissures was proposed. This method can be used to more accurately calculate the stress-strain state of rocks.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46833884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Different topographical support bases are used to solve the problems of raising and tracing underground mining works. These are frequently used on polygonal path with two fixed points, where the coordinates of the end points are given, and the measured quantities are angles and distances. Depending on the errors of the quantities measured before processing and the errors after processing, the coordinates of the points of the polygonal route and the orientations of the sides are determined with the precision, that fundamentally, technically and economically determines the execution of the designed mining works.
{"title":"Processing of measured quantities in a mining polygon route","authors":"A. Filip, L. Filip","doi":"10.52321/igh.36.1.59","DOIUrl":"https://doi.org/10.52321/igh.36.1.59","url":null,"abstract":"Different topographical support bases are used to solve the problems of raising and tracing underground mining works. These are frequently used on polygonal path with two fixed points, where the coordinates of the end points are given, and the measured quantities are angles and distances. Depending on the errors of the quantities measured before processing and the errors after processing, the coordinates of the points of the polygonal route and the orientations of the sides are determined with the precision, that fundamentally, technically and economically determines the execution of the designed mining works.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":"91 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83221128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Karst has a wide distribution, both throughout the world and in Bulgaria. The groundwater formed in it are important for providing water for the population and for the existence of a number of ecosystems. Considering the importance of karst springs, an international project "Most Important Karst Aquifer Springs" – MIKAS was started. The project aims to bring together the joint efforts of scientists from different countries in order to characterize and promote the most important springs in the respective countries. Its organization is carried out by an international Advisory Board, and National experts from the respective country are involved in its implementation. The main task is to prepare Global and National lists of karst springs representing world and national natural heritage for each country. Determining the importance of each source is carried out after applying historical, aesthetic, economic, scientific and ecological criteria. In order to unify the selection of representative springs by the experts from the different countries, the Advisory Board has proposed a methodology for preparing accompanying forms with complex information, including maps, photos, graphics and others. As a sample, two completed forms are attached to the adopted Methodology – for the Khanis spring, Iraq, proposed for inclusion in the Global List and for the Vrelo Mlave – for the National List of Serbia. In Bulgaria, it has been established that there are over 150 karst springs of regional and local importance on its territory. Part of the accepted general criteria is applicable to each of them with different weight. From these springs, after review and discussion of the existing information, it is planned to select a part of them for a more detailed evaluation and possibly their inclusion in an extended National list. The weighting of the various criteria will be determined and a summary assessment and ranking will be made based on it. On this basis, a National list will be prepared, which will include the most highly rated karst springs with the necessary illustrative material for each spring. This list will be presented to the Project Advisory Board and it will be discussed with them which of the springs could be included in the Global List.
{"title":"Project “Most Important Karst Aquifer Springs” (MIKAS) and Bulgaria's participation in it","authors":"A. Benderev","doi":"10.52321/igh.36.1.45","DOIUrl":"https://doi.org/10.52321/igh.36.1.45","url":null,"abstract":"Karst has a wide distribution, both throughout the world and in Bulgaria. The groundwater formed in it are important for providing water for the population and for the existence of a number of ecosystems. Considering the importance of karst springs, an international project \"Most Important Karst Aquifer Springs\" – MIKAS was started. The project aims to bring together the joint efforts of scientists from different countries in order to characterize and promote the most important springs in the respective countries. Its organization is carried out by an international Advisory Board, and National experts from the respective country are involved in its implementation. The main task is to prepare Global and National lists of karst springs representing world and national natural heritage for each country. Determining the importance of each source is carried out after applying historical, aesthetic, economic, scientific and ecological criteria. In order to unify the selection of representative springs by the experts from the different countries, the Advisory Board has proposed a methodology for preparing accompanying forms with complex information, including maps, photos, graphics and others. As a sample, two completed forms are attached to the adopted Methodology – for the Khanis spring, Iraq, proposed for inclusion in the Global List and for the Vrelo Mlave – for the National List of Serbia. In Bulgaria, it has been established that there are over 150 karst springs of regional and local importance on its territory. Part of the accepted general criteria is applicable to each of them with different weight. From these springs, after review and discussion of the existing information, it is planned to select a part of them for a more detailed evaluation and possibly their inclusion in an extended National list. The weighting of the various criteria will be determined and a summary assessment and ranking will be made based on it. On this basis, a National list will be prepared, which will include the most highly rated karst springs with the necessary illustrative material for each spring. This list will be presented to the Project Advisory Board and it will be discussed with them which of the springs could be included in the Global List.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":"70 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74127493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Dematteis, M. Thüring, Francisco Alvarado, Gabriele De Carli
This paper refers to experiences developed on the deep tunnels design of the Snowy 2.0 pumped-storage hydroelectric project in NSW, Australia. The 27 km long waterway and the Power Station Complex are about 800 m below ground, and in a complex tectonic and lithological setting. Long-term temperature monitoring in boreholes has been used to infer an empirical thermal model along the deep tunnels, which is presented as an example of input data for the ventilation design during construction, and for durability design during operation. An innovative aspect of this paper is related to the graphical interpretative method of borehole temperature logs that is proposed to infer downward or upward groundwater flows and predict the hydrogeological behavior of fractured and faulted zones that cross the tunnel alignment. A large campaign of thermal acquisition boreholes, performed using an ATV probe, identified local anomalies of the geothermal gradient, which were correlated to permeability and pressure data measured in the boreholes, to identify zones of greater permeability that intersect the tunnels. Furthermore, the application of thermal measurements during tunnel excavation is proposed as an additional tool for the prediction of water inflow or identification of zones to be pre-grouted and/or drained. Thematic collection: This article is part of the Leading to Innovative Engineering Geology Practices collection available at: https://www.lyellcollection.org/topic/collections/leading-to-innovative-engineering-geology-practices
{"title":"Contribution of temperature measurements to the hydrogeological model in the Snowy 2.0 deep tunnels","authors":"A. Dematteis, M. Thüring, Francisco Alvarado, Gabriele De Carli","doi":"10.1144/qjegh2022-056","DOIUrl":"https://doi.org/10.1144/qjegh2022-056","url":null,"abstract":"This paper refers to experiences developed on the deep tunnels design of the Snowy 2.0 pumped-storage hydroelectric project in NSW, Australia. The 27 km long waterway and the Power Station Complex are about 800 m below ground, and in a complex tectonic and lithological setting. Long-term temperature monitoring in boreholes has been used to infer an empirical thermal model along the deep tunnels, which is presented as an example of input data for the ventilation design during construction, and for durability design during operation. An innovative aspect of this paper is related to the graphical interpretative method of borehole temperature logs that is proposed to infer downward or upward groundwater flows and predict the hydrogeological behavior of fractured and faulted zones that cross the tunnel alignment. A large campaign of thermal acquisition boreholes, performed using an ATV probe, identified local anomalies of the geothermal gradient, which were correlated to permeability and pressure data measured in the boreholes, to identify zones of greater permeability that intersect the tunnels. Furthermore, the application of thermal measurements during tunnel excavation is proposed as an additional tool for the prediction of water inflow or identification of zones to be pre-grouted and/or drained.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Leading to Innovative Engineering Geology Practices collection available at:\u0000 https://www.lyellcollection.org/topic/collections/leading-to-innovative-engineering-geology-practices\u0000","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47556035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Ranguelov, R. Borg, E. Spassov, Fathimath Shadiya, Antoaneta Frantzova
The Vs_30 refers to the velocity of transversal seismic waves in the upper earth crust (surface shallow depths) in the 0-30 m interval. This parameter reflects the integral ground properties and is used in almost all seismic hazard assessment software. The determination of Vs_30 is important, especially in the case of urban territories, where in-situ measurements are very difficult and sometimes impossible due to dense urban areas, large anthropogenic noise and the need of expensive boreholes. The paper presents a methodology for extracting necessary data and information from archival sources, mainly geophysical measurements frequently executed for different prospecting purposes. The methodology for assessment of the integral values of Vs_30 is proposed for the definition of seismic hazard maps in Bulgaria. The methodology proposed, based primarily on archive data, represents an effective approach with significant results, especially for the intensive urbanized town territories located in high seismic areas.
{"title":"Determination of Vs_30 from existing geophysical investigation data","authors":"B. Ranguelov, R. Borg, E. Spassov, Fathimath Shadiya, Antoaneta Frantzova","doi":"10.52321/igh.36.1.35","DOIUrl":"https://doi.org/10.52321/igh.36.1.35","url":null,"abstract":"The Vs_30 refers to the velocity of transversal seismic waves in the upper earth crust (surface shallow depths) in the 0-30 m interval. This parameter reflects the integral ground properties and is used in almost all seismic hazard assessment software. The determination of Vs_30 is important, especially in the case of urban territories, where in-situ measurements are very difficult and sometimes impossible due to dense urban areas, large anthropogenic noise and the need of expensive boreholes. The paper presents a methodology for extracting necessary data and information from archival sources, mainly geophysical measurements frequently executed for different prospecting purposes. The methodology for assessment of the integral values of Vs_30 is proposed for the definition of seismic hazard maps in Bulgaria. The methodology proposed, based primarily on archive data, represents an effective approach with significant results, especially for the intensive urbanized town territories located in high seismic areas.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":"5 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82466148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Radon (222Rn) is a radioactive gas and formed as a result of the radioactive decay of radium. 222Rn relieved from the ground could accumulate in the building and contribute to human exposure. Exposure to indoor radon and its decay products contributes to half of the annual dose received by the public from all natural radioactive sources. Radon is recognized as a carcinogenic agent by the WHO and is the second leading cause of lung cancer after tobacco smoke. The radon concentration in buildings and the exposure to radon depend on many factors, but it can be assumed that geology is the main factor influencing the variation of indoor radon. In this regard, the geogenic radon potential (GRP) of the terrain is the probability of the presence of high radon concentration in a building, the genesis of which is directly related to the influence of the earth's surface, and not e.g. from building materials. In addition, there is a concept “radon index”, which is used to characterize GRP. One of the approaches for quantifying the radon index is based on a multivariate cross-tabulation, which includes two parameters – radon concentration in soil gas and gas permeability of the earth layer. Till 2019, complex studies concerning correlation between the measured radon concentrations and bedrock geology in Bulgaria are only scarce and quite general. In the last three years, there are attempts for detailed investigations for evaluation of the bedrock and superficial geology associating with radon potential or/and radon index determinations. Therefore, research works on geogenic radon so far in Bulgaria can be divided into two main groups: regional research works related to the "radon-rock" relationship and local research aimed at determining the radon index at specific sites. In the first group appertain investigations about defining the rock formations in Bulgaria, in their outcrop presence, with possible high radon potential based on geological and published more general “radon–rock correlations” data. Based on that, a GIS based map for the spatial distribution of the particular rock types in accordance with the expected radon potential is made. Also to this group belongs a study concerning spatial sampling design for the use of the polygons (Sliven Province) as the unit of sampling, data collection, and analysis and reduces the number of observations, as well as would optimize the gathering, analysis and systematization of the data for the preparation of a methodology for the preparation of geogenic radon potential map. In the second group appertain investigations of the radon index determination at the two pilot sites affected by fault systems in Sofia.
{"title":"Status of the geogenic radon potential investigations in Bulgaria","authors":"Boyka Mihaylova, M. Trayanova, Monika Mutovska","doi":"10.52321/igh.36.1.15","DOIUrl":"https://doi.org/10.52321/igh.36.1.15","url":null,"abstract":"Radon (222Rn) is a radioactive gas and formed as a result of the radioactive decay of radium. 222Rn relieved from the ground could accumulate in the building and contribute to human exposure. Exposure to indoor radon and its decay products contributes to half of the annual dose received by the public from all natural radioactive sources. Radon is recognized as a carcinogenic agent by the WHO and is the second leading cause of lung cancer after tobacco smoke. The radon concentration in buildings and the exposure to radon depend on many factors, but it can be assumed that geology is the main factor influencing the variation of indoor radon. In this regard, the geogenic radon potential (GRP) of the terrain is the probability of the presence of high radon concentration in a building, the genesis of which is directly related to the influence of the earth's surface, and not e.g. from building materials. In addition, there is a concept “radon index”, which is used to characterize GRP. One of the approaches for quantifying the radon index is based on a multivariate cross-tabulation, which includes two parameters – radon concentration in soil gas and gas permeability of the earth layer. Till 2019, complex studies concerning correlation between the measured radon concentrations and bedrock geology in Bulgaria are only scarce and quite general. In the last three years, there are attempts for detailed investigations for evaluation of the bedrock and superficial geology associating with radon potential or/and radon index determinations. Therefore, research works on geogenic radon so far in Bulgaria can be divided into two main groups: regional research works related to the \"radon-rock\" relationship and local research aimed at determining the radon index at specific sites. In the first group appertain investigations about defining the rock formations in Bulgaria, in their outcrop presence, with possible high radon potential based on geological and published more general “radon–rock correlations” data. Based on that, a GIS based map for the spatial distribution of the particular rock types in accordance with the expected radon potential is made. Also to this group belongs a study concerning spatial sampling design for the use of the polygons (Sliven Province) as the unit of sampling, data collection, and analysis and reduces the number of observations, as well as would optimize the gathering, analysis and systematization of the data for the preparation of a methodology for the preparation of geogenic radon potential map. In the second group appertain investigations of the radon index determination at the two pilot sites affected by fault systems in Sofia.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":"64 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87267236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The study covers a coastal slope along the northern Bulgarian Black Sea coast near Cape Kaliakra, Zelenka locality. The slope is composed of Miocene (Sarmatian), unconsolidated aragonite sediments with limestone interbeds (Topola Formation) and a steep limestone rock ridge (Karvuna Formation). Water flows along the surface of the slope, attached to the karstified and cracked limestones of the two formations. An assessment was made of the material eroded from the slope, composed of aragonite sediments of the Topola Formation, for the period from September 2018 to October 2022. The quantities of this material were measured and laboratory tests of the aragonite sediments were carried out. Their classification characteristics have been determined - grain size composition and plasticity index. Geotechnical studies and mapping of the coastal slope showed that erosion processes in the studied area represent a real geological hazard and can affect the stability of the slope, as well as the integrity of the road.
{"title":"Erosion of Coastal Slope in the Zelenka locality, Northern Black Sea Coast of Bulgaria","authors":"Rosen Nankin, M. Krastanov, P. Ivanov","doi":"10.52321/igh.36.1.3","DOIUrl":"https://doi.org/10.52321/igh.36.1.3","url":null,"abstract":"The study covers a coastal slope along the northern Bulgarian Black Sea coast near Cape Kaliakra, Zelenka locality. The slope is composed of Miocene (Sarmatian), unconsolidated aragonite sediments with limestone interbeds (Topola Formation) and a steep limestone rock ridge (Karvuna Formation). Water flows along the surface of the slope, attached to the karstified and cracked limestones of the two formations. An assessment was made of the material eroded from the slope, composed of aragonite sediments of the Topola Formation, for the period from September 2018 to October 2022. The quantities of this material were measured and laboratory tests of the aragonite sediments were carried out. Their classification characteristics have been determined - grain size composition and plasticity index. Geotechnical studies and mapping of the coastal slope showed that erosion processes in the studied area represent a real geological hazard and can affect the stability of the slope, as well as the integrity of the road.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":"27 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78154996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The territory of Bulgaria is affected by almost all dangerous geodynamic processes, such as landslides, rockfalls, erosion, debris flows, abrasion, etc. In addition, the selection of countermeasures raises the serious issue of their periodic monitoring in order to protect human life and infrastructure. The general idea of this study is to provide information about the different methods used for monitoring the above-mentioned hazardous geodynamic processes. After a comprehensive review of the available scientific developments, the author found that in the field of engineering geology, articles related to the monitoring of given processes are almost absent. The purpose of the article is to provide detailed information about the various methods of monitoring dangerous geodynamic processes and their fields of application. Due to the limitation of the article`s volume, only the main features of the utilized and available monitoring methods in Bulgaria will be presented. Hence a further, more comprehensive overview will be in a great need.
{"title":"Methods used for monitoring geodynamic processes on the territory of Bulgaria","authors":"M. Krastanov","doi":"10.52321/igh.36.1.25","DOIUrl":"https://doi.org/10.52321/igh.36.1.25","url":null,"abstract":"The territory of Bulgaria is affected by almost all dangerous geodynamic processes, such as landslides, rockfalls, erosion, debris flows, abrasion, etc. In addition, the selection of countermeasures raises the serious issue of their periodic monitoring in order to protect human life and infrastructure. The general idea of this study is to provide information about the different methods used for monitoring the above-mentioned hazardous geodynamic processes. After a comprehensive review of the available scientific developments, the author found that in the field of engineering geology, articles related to the monitoring of given processes are almost absent. The purpose of the article is to provide detailed information about the various methods of monitoring dangerous geodynamic processes and their fields of application. Due to the limitation of the article`s volume, only the main features of the utilized and available monitoring methods in Bulgaria will be presented. Hence a further, more comprehensive overview will be in a great need.","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":"154 8 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83144716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present study aims to investigate the mechanical properties and Acoustic Emission (AE) response of carbonate fault rocks in Lefkada Island, Greece. In the aforementioned region, tectonic processes have resulted in the formation of fault breccias with poor mechanical properties and complex behavior. In these weak formations, conventional laboratory testing methods are restricted due to their disintegration during sampling and specimen preparation. A novel sample preparation and laboratory testing technique are used jointly with a back-analysis of a co-seismic landslide, that occurred during a M w 6.5 earthquake in 2015. These two approaches are employed to characterize and predict the mechanical behavior of these formations. The uniaxial compressive strength (UCS) of the fault breccias, determined in the laboratory, has a wide range primarily due to the complex nature of the material. The back-analysis, using a 3D limit equilibrium method, proves that the shear strength of the in-situ material is significantly lower than that determined in the laboratory. Finally, the acoustic emission response of fault breccias was different compared to that of brittle rocks. B-value analysis and the damage variable evolution indicate that the accumulated damage within fault breccias is higher than expected and thus they are more prone to fatigue. Thematic collection: This article is part of the Leading to Innovative Engineering Geology Practices collection available at: https://www.lyellcollection.org/topic/collections/leading-to-innovative-engineering-geology-practices
{"title":"Mechanical properties and Acoustic Emission response of carbonate fault breccias, a study from Greece","authors":"V. Kallimogiannis, C. Saroglou","doi":"10.1144/qjegh2022-088","DOIUrl":"https://doi.org/10.1144/qjegh2022-088","url":null,"abstract":"\u0000 The present study aims to investigate the mechanical properties and Acoustic Emission (AE) response of carbonate fault rocks in Lefkada Island, Greece. In the aforementioned region, tectonic processes have resulted in the formation of fault breccias with poor mechanical properties and complex behavior. In these weak formations, conventional laboratory testing methods are restricted due to their disintegration during sampling and specimen preparation. A novel sample preparation and laboratory testing technique are used jointly with a back-analysis of a co-seismic landslide, that occurred during a M\u0000 w\u0000 6.5 earthquake in 2015. These two approaches are employed to characterize and predict the mechanical behavior of these formations. The uniaxial compressive strength (UCS) of the fault breccias, determined in the laboratory, has a wide range primarily due to the complex nature of the material. The back-analysis, using a 3D limit equilibrium method, proves that the shear strength of the in-situ material is significantly lower than that determined in the laboratory. Finally, the acoustic emission response of fault breccias was different compared to that of brittle rocks. B-value analysis and the damage variable evolution indicate that the accumulated damage within fault breccias is higher than expected and thus they are more prone to fatigue.\u0000 \u0000 \u0000 Thematic collection:\u0000 This article is part of the Leading to Innovative Engineering Geology Practices collection available at:\u0000 https://www.lyellcollection.org/topic/collections/leading-to-innovative-engineering-geology-practices\u0000","PeriodicalId":20937,"journal":{"name":"Quarterly Journal of Engineering Geology and Hydrogeology","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2022-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44148031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nasar Khan, Muhammad Ejaz Siddiqui, N. Ullah, M. Awais, Salman Khurshid
Hydropower projects provide excellent opportunities to cope with rising energy demands, however, their geological and geotechnical evaluation is fundamental to ensure their long-term performance and stability. Thus, geological and geotechnical investigations were carried out to evaluate the feasibility of a tunnel (7 m diameter and 1880 m length) for Koto Hydropower Project, Khyber Pakhtunkhwa, Pakistan. Five investigation boreholes with a cumulative depth of 145 m were drilled and samples were collected for qualitative observation and laboratory analyses. The performed geotechnical investigations include Lugeon and permeability tests to estimate hydraulic conductivity of the associated rocks. In the boreholes, lithologies and discontinuities such as joints, fractures, veins and shear zones were identified. Lithologic logging, rock quality designation and percentage core recovery were performed to understand rock behaviour and strength. The rocks encountered are mainly gabbronorites and granodiorites with some amphibolites. The bed rock strength is designated as R4 (strong) with minor amount of R3 (moderate) that indicates suitability and feasibility for tunnel construction. Main Mantle Thrust (MMT) is the major tectonic feature which is located towards the southern side of the study area, however, seismicity along it is optimal. The geological and geotechnical investigation deciphered that the tunnel site of the project is feasible for construction.
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