1 Soil Exploration Soil Exploration Introduction Introduction n The The field field and and laboratory laboratory investigations investigations required required to to obtain obtain the the necessary necessary data data for for the the soils soils for for proper proper design design and and successful successful construction construction of of any any structure structure at at the the site site are are collectively collectively called called soil soil exploration exploration. n The The choice choice of of the the foundation foundation and and its its depth, depth, the the bearing bearing capacity, capacity, settlement settlement analysis analysis and and such such other other important important aspects aspects depend depend very very much much upon upon the the various various engineering engineering properties properties of of the the foundation foundation soils soils involved involved. The primary objectives of soil exploration are The primary objectives of soil exploration are n Determination Determination of of the the nature nature of of the the deposits deposits of of soil soil. n Determination Determination of of the the depth depth and and thickness thickness of of the the various various soil soil strata strata and and their their extent extent in in the the horizontal horizontal direction direction. n The The location location of of ground ground water water table table (GWT) (GWT). n Obtaining Obtaining soil soil and and rock rock samples samples from from the the various various strata strata. n The The determination determination of of the the engineering engineering properties properties of of the the soil soil and and rock rock strata strata that that affect affect the the performance performance of of the the structure structure. n Determination Determination of of the the in in-situ situ properties properties by by performing performing field field tests tests. Soil data required Soil data required v Soil profile Soil profile v Index properties v Strength & compressibility characteristics v Others (e.g., water table depth) - layer thickness and soil identification - water content, Atterberg limits (Liquid Limit, Plastic Limit, Shrinkage Limit) etc. -c′ ,c u , φ′ ,C c , OCR, … Sivakugan ü Aerial photographs Aerial photographs ü Topographical maps Topographical maps ü Existing site investigation reports (for nearby sites) Existing site investigation reports (for nearby sites) ü Other information from local councils, literature Other information from local councils, literature First stage of site investigation. Negligible cost. Look for currently available information Sivakugan Site Reconnaissance Site Reconnaissance ü Site access Site access ü Topography Topography ü Site geology Site geology ü Conditions of adjacent structures Conditions of adjacent structures ü Any obvious problems foreseen? Any obvious problems foreseen? A site visit and chat with locals. Sivakugan PDF Creator - PDF4Free v3.0 http://www.pdf4free.com
7
Embed
Soil Exploration - ERNETnilanjan/CE20100_Lecture_4-GPS and Soil... · 1 Soil Exploration Introduction n The field and laboratory investigations required to obtain the necessary data
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
1
Soil ExplorationSoil Exploration
IntroductionIntroductionnn TheThe fieldfield andand laboratorylaboratory investigationsinvestigations requiredrequired toto
nn DeterminationDetermination ofof thethe inin--situsitu propertiesproperties byby performingperformingfieldfield teststests..
Soil data requiredSoil data required
vv Soil profileSoil profile
v Index properties
v Strength & compressibility characteristics
v Others (e.g., water table depth)
- layer thickness and soil identification
- water content, Atterberg limits (Liquid Limit,Plastic Limit, Shrinkage Limit) etc.
- c′, cu, φ′, Cc, OCR, …
Sivakugan
üü Aerial photographsAerial photographsüü Topographical mapsTopographical mapsüü Existing site investigation reports (for nearby sites)Existing site investigation reports (for nearby sites)üü Other information from local councils, literatureOther information from local councils, literature
First stage of site investigation. Negligible cost. Lookfor currently available information
Sivakugan
Site ReconnaissanceSite Reconnaissance
üü Site accessSite accessüü TopographyTopographyüü Site geologySite geologyüü Conditions of adjacent structuresConditions of adjacent structuresüü Any obvious problems foreseen?Any obvious problems foreseen?
A site visit and chat with locals.
Sivakugan
PDF Creator - PDF4Free v3.0 http://www.pdf4free.com
nn The methods available for soil exploration mayThe methods available for soil exploration maybe classified as followsbe classified as follows
nn Direct methods ... Test pits, trial pits or trenchesDirect methods ... Test pits, trial pits or trenchesnn SemiSemi--direct methods ... Boringsdirect methods ... Boringsnn Indirect methods ... Soundings or penetration testsIndirect methods ... Soundings or penetration tests
and geophysical methodsand geophysical methods
Test PitTest PitEnables visual inspection, locating strata boundaries, andaccess for undisturbed block samples.
nn Samples of soil taken out of natural deposits for testingSamples of soil taken out of natural deposits for testingmay be classified as:may be classified as:DisturbedDisturbed samplesampleUndisturbedUndisturbed samplesample
nn AA disturbeddisturbed samplesample isis thatthat inin whichwhich thethe naturalnatural structurestructureofof thethe soilsoil getsgets modifiedmodified partlypartly oror fullyfully duringduring samplingsampling
nn Disturbed but representative samples can generally beDisturbed but representative samples can generally beused forused for
vv GrainGrain--size analysissize analysisvv Determination of liquid and plastic limitsDetermination of liquid and plastic limitsvv Specific gravity of soil solidsSpecific gravity of soil solidsvv Organic content determinationOrganic content determinationvv Soil classificationSoil classification
qq Undisturbed samples must be used forUndisturbed samples must be used forvv Consolidation testConsolidation testvv Hydraulic conductivity testHydraulic conductivity testvv Shear strength testShear strength test
nn The minimum depth of boring for a building with aThe minimum depth of boring for a building with awidth of 30.5 m (100 ft) will be as followswidth of 30.5 m (100 ft) will be as follows (Sowers and Sowers, 1970)(Sowers and Sowers, 1970)
No of storiesNo of stories Boring depthBoring depth11 3.5 m3.5 m22 6.0 m6.0 m33 10 m10 m44 16 m16 m55 24 m24 m
Standard Penetration TestStandard Penetration Test
nn Advantages:Advantages:üü No line of sight is requiredNo line of sight is requiredüü The equipment is suitably weatherproofThe equipment is suitably weatherproofüü One person operation with significant saving inOne person operation with significant saving in
time andtime and labourlabourüü Operation do not need high level of skillOperation do not need high level of skillüü Position may be fixed on land, air, seaPosition may be fixed on land, air, seaüü Baseline of hundreds of km can be measured toBaseline of hundreds of km can be measured to
GPS SegmentsGPS Segmentsnn 29 satellites29 satellitesnn Satellites are in almost circular orbitsSatellites are in almost circular orbitsnn 20200 km from earth (3 times the radius of earth)20200 km from earth (3 times the radius of earth)nn With orbit times just under 12 hrs.With orbit times just under 12 hrs.nn The six orbit planes are equally spacedThe six orbit planes are equally spacednn At least four satellite will always be in view at leastAt least four satellite will always be in view at least
1515°°above the horizontalabove the horizontalnn Weight of each satellite is 850 kgWeight of each satellite is 850 kgnn Design life from 7.5 years to 10 yearsDesign life from 7.5 years to 10 years
PDF Creator - PDF4Free v3.0 http://www.pdf4free.com
ApplicationsApplicationsnn Plate tectonicsPlate tectonicsnn NavigationNavigationnn Geographical information system (GIS)Geographical information system (GIS)nn Deformation monitoringDeformation monitoring
PDF Creator - PDF4Free v3.0 http://www.pdf4free.com