Investigation methods in Geotechnics VŠB-TUO – Faculty of Civil Engineering Department of Geotechnics and Underground Engineering Geotechnics • Applied geology (engineering geology and hydrogeology etc.)? • Geomechanics • Soil mechnics • Rock mechanics • Mechanics of snow and ice • Foundation engineering • Underground engineering • Another branches – eg. Earth structures, environmental geotechnics, quarrying etc. Karl von Terzaghi Engineering geology • Interdisciplinary between natural and technical sciences • Releases from physical geology, historical and regional geology, geomorphology, geophysics, hydrogeology, structural geology, petrography etc. • Studies and characterizes mutual relationship among rock mass, groundwater, surface water, geomorphology and their effect on engineering project • Utilizes laboratory and field methods including state of the art remote sensing methods Hans Cloos - Quido Záruba – Vojtěch Mencl Zdroj: www.geology.cz Rock environment – Foundation soil - Investigation • Foundation soil = terminus technicus covering rock and soil environment interaction (thru the foundations) with the structure. It is necessary to include rock environment surrounding the structure! • Errors and imperfections of investigation have impacts on the structure life time. • Errors discovering during the: • Design (cheapest correction) • Construction (more expensive) • Operation (the worst case; the most expensive!) • Site Investigation cost (terminology) • Small simple structure cca 0,1-0,5 % of capital cost (investment) • Conventional structure cca 0,25-1 % of capital cost • Large or unusual structure 0,5-2 % of capital cost (dams, large bridges, tunnels, deep basements etc.) Investigation methods • Site investigation focused on: – General engineering geological problems – Special engineering geological problems • Desk study • Field methods • Laboratory methods • Data processing Legislation in Czech Republic Vyhláška č. 368/2004 Sb. Vyhláška o geologické dokumentaci Vyhláška č. 268/2009 Sb. Vyhláška o technických požadavcích na stavby § 18 Zakládání staveb Decree No. 268/2009 of Legal code Decree on Technical Requirements for Buildings § 18 Structure foundation Buildings must be constructed in a manner appropriate to the underlying conditions (rock environment) found by the geological survey and must meet the requirements given by the normative values, without threatening the stability of other structures. Standard ČSN EN 1997-1 Geotechnical data according to ČSN EN 1997-1/2006 (73 1000) (part 3) • Careful collection, recording and interpretation of geotechnical information shall always be made. This information shall include geology, geomorphology, seismicity, hydrology and history of the site. Indications of the variability of the ground shall be taken into account • Site investigations have to take into account the heterogeneity and variability of the ground • Site investigations shall be planned taking into account the construction and performance requirements of the proposed structure. The scope of geotechnical investigations shall be continuously reviewed as new information is obtained during execution of the work • Routine field investigations and laboratory testing shall be carried out and reported generally in accordance with internationally recognised standards and recommendations. • Deviations from these standards and additional test requirements shall be reportedPožadavky na laboratorní a terénní zkoušky mají být převzaty z EN 1997-2 (Eurocode 7 Geotechnical design – Part 2: Ground investigation and testing) Geotechnical investigation according to ČSN EN 1997-1/2006 (73 1000) (part 3) • Geotechnical investigations shall provide sufficient data concerning the ground and the ground-water conditions at and around the construction site for a proper description of the essential ground properties and a reliable assessment of the characteristic values of the ground parameters to be used in design calculations • The composition and amount of the geotechnical investigations shall be adjusted to the particular investigation phase and the geotechnical category (see EN 1997-2, Section 2) it have to be done as soon as possible • The investigations should include visual inspections of the site to enable the design assumptions to be verified during construction • Průzkum je zpravidla členěn v rozsahu a v čase na: • ORIENTAČNÍ • Preliminary • Detail • DOPLŇKOVÝ Ground Investigation - ČSN P 73 1005 Cost benefits - procedures Cost benefits - techniques Aims of investigation GONZÁLEZ DE VALLEJO, Luis I. a Mercedes FERRER. Geological engineering. CRC Press, c2011. ISBN 978-0-415-41352-7. Procedures GONZÁLEZ DE VALLEJO, Luis I. a Mercedes FERRER. Geological engineering. CRC Press, c2011. ISBN 978-0-415-41352-7. Sources of information GONZÁLEZ DE VALLEJO, Luis I. a Mercedes FERRER. Geological engineering. CRC Press, c2011. ISBN 978-0-415-41352-7. Morphological, Geological conditions GONZÁLEZ DE VALLEJO, Luis I. a Mercedes FERRER. Geological engineering. CRC Press, c2011. ISBN 978-0-415-41352-7. Hong Kong 1972 20 Mass wasting - general • Creep • Landslides • Flow • Rock falling Mass wasting types Register of ground instabilities The register of slope instabilities of the CGS is made available in the form of a map application and the individual records are also accessible by searching in the database of slope instabilities of the Czech Geological Survey. https://mapy.geology.cz/svahove_nestability/ Landslide Bystřička 24 Landslide Bystřička 25 Mass wasting factors • Active Increasing of stress in the slope (e.g. slope loading) • Passive Decresing of rock mass strength (e.g. weathering) Mass wasting factors • Permanent • Epizodic • Trigger Last initiation factor of mass wasting Man made activities • Urbanization, irrigation • Deforestation in place of weak rocks • Changes in morphology – Cuts – Embankments on slopes • Dam construction • Mining activities • Drilling and exploitation of oil and gas Landslide elemination - general • Remote sensing – image analysis - LIDAR • 3D morphological data assessment by in situ measurement • Maps of mass wasting • Aplication of geological and engineering approaches in design and realization slope stability projects Case study Dobkovičky.