Importance of Ground Investigations in Site Investigations

Importance of run a undercoatwork probes in turn up investigatingsGeotechnical tarradiddleAli AleffarContentsIntroductionSite investigating procedure coif 1 desk theme and reconnaissance surveyStage 2 Ground probe, abbreviation and laboratory quizPhase 1 or encroaching(prenominal) (sampling)PhotographsPhase 2 non-intrusive or Geophysical rank geographic expedition.Laboratory examStage 3 the locate investigation make knownREPORT abridgmentSubsurface Situations innovation Recomm poleationsGeotechnical failure exampleCritical AnalysisRecommendations proofReferencesIntroductionIn order to specify the geotechnical and geoenvironmental issues in the context of the suggested end-use of the site, site investigation raise be done for this purpose. A geotechnical site investigation is the process of assembling info and evaluating the conditions of the site for the purpose of introductioning and constructing the innovation for a social organization, much(prenominal) as a make, plant or bridge, In addition to that this report contains the site investigation procedure and how the mistakes in site investigation process whitethorn lead to a disaster such(prenominal) as what the example below illust dictates, collapsing of an important building after slaying a subway tunnel under its ara, the reasons behind that and how the poorly-done site investigation or avocation the exemplification without taming the procedure to proper the environment and share of the shake off. Good planning for and management of a geotechnical site investigation is the trace to sustaining sufficient and correct site information for designing a body structure in a magazinely manner and with minimum cost for the drift needed.Site investigation procedureTo carry out the site investigation procedure there are 4 stages to doStage 1 desk study and reconnaissance surveyStage 2 ground investigation, summary and laboratory testStage 3 reportStage 4 design and materials r ecommendation.ONLINE Available at http//www.rsa-geotechnics.co.uk/pages.asp?fld_pages_ID=51. Accessed 18 February 2015Stage 1 Desk study and reconnaissance surveyTime spent in reconnaissance is never wasted. The purpose of the desk study is to identify change in the three estates use, via Ordinance Survey maps, Kellys Trade Directories and other historical publicly addressable records In addition to walkover survey. The history of the site and what it is utilise for and if whether if it has contaminated the smear and how deep it has effected it. Using satellite imaging, Geological maps, topographical maps, Soil survey maps, Aerial photographs and existing site investigation reports.GEOTECHNICAL turn up INVESTIGATION GUIDELINES FOR BUILDING FOUNDATIONS IN PERMAFROST. 2010.Stage 2 Ground investigation, analysis and laboratory testGround investigation or site exploration rat be classified into two phasesPhase 1 or intrusive (sampling)It is important that a geotechnical speci alist or an engineer with cognition and skills to document terra firma stratigraphy, their variations, and the existence of a specific circumstance to come across the progress of test holes advance. 1.5 m is the depth intervals that samples should be taken and blind drunk in plastic bags for transport to a laboratory for testing. Disturbed samples are derived from backhoe and air-track and auger drills. In addition, representative broken/disturbed samples should be roll up to provide samples at 1.5 m depth intervals for laboratory testing in addition to get a well representative sample the side by side(p) sampling-Disturbed samples undisturbed samples- some methods are applyTrial setsHand excavated boreholes subscriber line percussion sluggishRotary drillingSonic drillingPhotographsPhotographs apprise document the site and the drill equipment in work progress. In addition, it must be taken of representative disturbed samples and all landed estate and pit cores.Smiths el ements of soil mechanics, 2014.Phase 2 non-intrusive or Geophysical site exploration. leaden and test pits afford definitive subsurface exploration. They plunder, however, be both time consuming and costly. In addition, they give subsurface conditions only at boring or test pit military positions, leaving massive areas in in the midst of for which conditions must be interpolated or appraised.Geophysical techniques, which are commonly used in highway work and in other applications, can be executed faster, less expensively and greater area can be covered more thoroughly, however, obtaining soil samples are still required from which nice determinations of soil properties can be made in order to avow and complement result obtained by geophysical methods. both particular geophysical methods that are seismic refraction (Fig1) and electrical resistivity.Resistance of soil to question of an electrical current is determined. Using values obtained therefrom, the depth and thickness of d iverse soil strata can be interpreted by specialists and estimated, with the aid of superfluous borings, some of the engine room properties of the subsurface material. SOILS AND FOUNDATIONS, 2001.Fig.1 (seismic refraction)Laboratory TestingLaboratory tests to obtain key properties of the ground will be adequate in the absolute majority of geotechnical site investigations. The index properties will be obtained by means of water content, particle size distribution, liquid, and plastic limit tests.Laboratory testing for engineering properties may be required for large buildings on complex lot of the ground stratigraphy. The types of engineering tests that may be conducted are consolidation, and less likely, front crawl strength and thermal properties tests.Stage 3 the site investigation reportThe key issues that should be noted shall bea) Project description restatedb) specify the site so that adjoin conditions that may influence the design and proceeding of the building footi ng are understood and designed forc) The schemeed end of the building helper life State the present and, climate and ground temperaturesd) Classify the soil strata consort to recognized Euro code and BS, based on quantitative laboratory resultse) State the significance of the stratigraphy conventional by the test hole program, measured ground temperature and the impact of climate warming rate on the recommended building foundation design(s)f) Identify foundation options proper for the proposed usefulness life of the building andg) Provide guidance for the construction and construction programming of the foundation for the building.GEOTECHNICAL SITE INVESTIGATION GUIDELINES FOR BUILDING FOUNDATIONS IN PERMAFROST. 2010.REPORT traceThe requested terms of the investigation are the master(prenominal) specifications that the content of the report depends on, the magnitude and difficulty of the structure, and the site condition. Hence, contents and expound of the reports may contra st. The epitome provides general contents based on literature and the writers experience.Structure information/necessities and building engineering design that the designer/design engineer provide. Testing and classification of the soils should be based on planetaryly recognized criterions. Engineering properties and foundation design requirements to take into consideration the service life of the proposed structure and the potential impact of climate warming. In addition, should contains the followingIntroductionIt is suggested that the report is prepared to provide information to the property owner, architect/design engineer and the contractor. As such, the introduction should make sufficient beginning toThe requested terms of reference of the investigation, and Scope of work provided in firm the requested terms of reference.BackgroundThe background provides the physical situation of the project and should includeProjected StructureDetail of the structure guides the extent an d detail of investigation. Thus, the architect/engineer should provide the information.Technical detail of the proposed structure, for instance, single or multi-story, plan area, above ground, slab-on grade, or with basement.Service life of the planned structure e.g., 20, 50 years or more.Geological SituationOverview of the site as provided by geomorphology and bedrock geology obtained from previous investigations and published information.Land definition of surface features of the immediate site that should include topography, vegetation and neighbouring structures.Hydrology and Immediate coat DrainageWater existence and surface flow may ingrain the design of surface grading and effect the ground temperatures.Subsurface SituationsInvestigation Program SummaryIncludes a description of the method/s used to evaluate the ground situations, equipment that grant to be used, test holes number, dates achieved, and laboratory tests conducted. tiny description of these should be presente d in the Appendix, prior to the field logs and laboratory testing.Design RecommendationsThe report should recommend the best foundation design suite the established ground conditions and the structure criteriaGEOTECHNICAL SITE INVESTIGATION GUIDELINES FOR BUILDING FOUNDATIONS IN PERMAFROST. 2010.Smiths elements of soil mechanics, 2014.Geotechnical failure exampleCollapsed archive and a neighbouring building, March 2009 On third of March 2009 at 1358, the archive building splitd (The archive was Germanys largest municipal archive, and the only one to survive World War II intact). Two adjacent apartment buildings also collapsed, killing two residents. The cologne historical Archive, suddenly disappeared into a cloud of dust and a pile of rubble. aft(prenominal) the sounds of buckling began, archive staff and visitors had enough time to escape the building, but its considerable historical holdings did not prove as fortunate. Flooding into the building pit was noticed that water. The building workers rapidly warned the staff and visitors of the archive, who evacuated the building. Shortly subsequently, the archive building collapsed as a result of an subsurface landslide hooked on the subway tunnel.as shown in the picture below Google map for the collapsed building location Two people were stuck under the debris and on person was ruling to be missed. The disaster has left residents in the urban center, shaken and angry. A close school remains evacuated and apartments next to the archive were also sucked into the 28-meter sinkhole. Many locals were scared of the next accident. The collapse also heavily damaged several surrounding apartment houses as well. The heaviest part of the tunnel construction was supposedly accurate 1-year earlier, but the tunnel floor had not been finished. The tunnel and station has been a controversial project in Cologne, with problems occurring as early as 2004 when a church steeple began experiencing tilt of 77-cm, greater t han 15 times what was predicted.Onlinehttp//www.spiegel.de/international/germany/cologne-archive-catastrophe-were-subway-builders-cautious-enough-a-612129.htmlAccessed 15 FebruaryCritical AnalysisAfter the starting of radical underground tunnel work many problems has been observed by residents and building workers such as an expansion correlative in the concrete ceiling, in which a crack the size of a hand had formed, cracks in the flooring in the basement boiler room and that the tower of St. Johann Baptist Church leaned by 77 centimeters15 times greater than what had been previously calculated. From the aforementioned examples successive events in Cologne city, the main reason of collapsing of the city archive building can be obviously concluded, which is insufficient bearing capacity of the soil to carry the onus of archive city building and some surrounding apartments after constructing the new tunnel in addition to some side factors which caused loosening of the ground and c avity formations that was inevitable in some areas.Witnesses who were close to the investigation commented that the cataclysm was likely caused by ground water sludge The whole issue points to an issue with the ground water, at the construction site may be related to lift levels of the Rhine River, which is situated very close to the collapsed building.The stability and deformations of tunnels can be affected by water by decreasing the rough-and-ready stress hence reducing the resistance to shearing stresses, by producing seepage forces towards the excavations borders. Drawdown of the water level and to time-dependent subsidence can be caused by the seepage-flow may due to consolidation. Moreover, the seepage forces may act towards the opening may discover its stability. The effects of groundwater in tunneling are ramified. Throughout tunnel excavation in a water-bearing ground, seepage stream in the direction of the opening occurs, because the crush at the excavation boundar y is, in general, equal to the atmospheric imperativeness and the tunnel acts consequently as a groundwater drain. Drawdown of the water level can be caused by seepage flow, to decrease in the discharge of walls, or to settlement and consolidation. Beyond these- in the broader sense- environmental influences such as travel levels of a River, which is situated close to the tunnel, large water inflows may have a severe impact on the serviceability throughout its action phase or obstruct excavation works. And thats what happened to the soil underneath the city of Cologne archive building where, the seepage which caused by rising levels of the Rhine river especially in that period of the year lead to weaken soil which is unable to carry the loads and that made the soil to fail and collapse the building to come down in a big whole,throughout collecting and analyzing the compile results, combined with the particular circumstances of the project, it can be summarized that the joint at t he interface are of layered rock damage resulted from the groundwater where it is the main internal cause of the tunnel failure. All of that can be resulted from poor-site investigation or it has not been done in the right way or misunderstanding for the data that collected from site investigation.Face instability severe seepage in the underground tunnlesRecommendationsThe local tests of the soil around the city archive had only been conducted before the city made the tender laissez passer and prior to the beginning of construction on the underground line. There were no subsequent soil tests once construction work had started. The city followed the standard procedure, so the first recommendation is the standard procedure should not be always followed but following the standard until specific limits depending on the project and other circumstances. In addition to sufficient reinforcing the potential weak soil spots during the tunnelling work For instance, during the construction o f a tunnel, flash-hardening bentonite rings must be always directly put in its place. Moreover, never left a hollow that could pull in the adjacent ground. Most of accidents can be avoided if more care is taken and fully understanding for the data collected from a very good site investigation and what to do according to it.In addition to that, for the tunnel situation, the groundwater level should be monitored and using dissimilar methods to control the seepage and consolidation of water in the tunnels, which lead to avoid the construction.Tunnel stability and deformations in water-bearing ground. p1-6ConclusionTo sum up, the ground investigation is a long process and takes a long time and it costs round (Buildings 0.05 0.2, Highways 0.2% 1.5%, Dams1% 3%) of the project cost and it ransoms up to 100% of the project and save human life and invaluable things such as the invaluable historical documents.Most of tunnels collapse accidents are resulted from the problems related wit h the ground water. 90% of collapsing accidents can be prevented by a good site investigation by an experienced team in this field.ReferencesRSA Geotechnics Geotechnical and Geoenvironmental Site Investigation What is Site Investigation?. 2015. RSA Geotechnics Geotechnical and Geoenvironmental Site Investigation What is Site Investigation?. ONLINE Available at http//www.rsa-geotechnics.co.uk/pages.asp?fld_pages_ID=51. Accessed 18 February 2015 1700Smiths elements of soil mechanics, Ian smith, 9th edition, 2014, WILEY BLACKWELL.SOILS AND FOUNDATIONS, Cheng Liu Jack B. Evett, 5th edition, 2001, prentice-HallDepartment of Public Works and go and Government of the north-west Territories (2010). GEOTECHNICAL SITE INVESTIGATION GUIDELINES FOR BUILDING FOUNDATIONS IN PERMAFROST. Northwest Territories. I. Holubec Consulting Incp3-8.Onlinehttp//www.spiegel.de/international/germany/cologne-archive-catastrophe-were-subway-builders-cautious-enough-a-612129.htmlaccessed 15 February 1200G An agnostou (2006). Tunnel stability and deformations in water-bearing ground. Zurich, Switzerland ETH, Swiss federal institute of technology. p1-6.Geotechnical and structural engineering centre (2014). wooing Analysis of soft and hard rock tunnel collapse and information management. Shandong, P.R China Ministry of Land and resources, China. p1227-1232.California Department of conservation (2013). Guidelines for Preparing Geological Reports for Regional-Scale environmental and Resource Management Planning. California, USA Department of surveying. p1-7.R. F. Craig (2004). CRAIGS SOIL MECHANICS. 7th ed. capital of the United Kingdom Spon Press. p30-70, p373-394.1