soil investigation methods
Post on 07-Jul-2018
261 Views
Preview:
TRANSCRIPT
-
8/18/2019 Soil Investigation Methods
1/20
Soil investigation methods
Semi direct methods
-
8/18/2019 Soil Investigation Methods
2/20
TECHNIQUES FOR LABORATORY INVESTIATIONS OF SOIL
AN! ROC" SA#$LES
-
8/18/2019 Soil Investigation Methods
3/20
-
8/18/2019 Soil Investigation Methods
4/20
A%ge& Bo&ingSuitable soil strata
• Soft soil- Up to depth of 3 to 6 m
• Clays (Soils which can stay open without casing or
drilling mud)
• Silts• Partially saturated sands
• Sandy soils with the help of casing
-
8/18/2019 Soil Investigation Methods
5/20
A. Screw/Worm Auger-gravelly or stony soils
B. Barrel Auger
C. Sampling Tube
. utch mud Auger!. "eat Auger
-
8/18/2019 Soil Investigation Methods
6/20
Sam'ling () a Hand A%ge&
-
8/18/2019 Soil Investigation Methods
7/20
Procedure
• Hand Auger Up to 3 ! 6 m
• "echanical Auger Up to #$ m%
• &lade of length '%3 - '% m is chosen
• otated until it is full of soil
• *ithdrawn to remo+e the soil to note the soil types at
+arious depths• epeat the process till , ! #' m as it gets difficult to
go after it
-
8/18/2019 Soil Investigation Methods
8/20
Advantages Limitations
• Useful or Su.surface /n+estigations
of Highway0 ailways And Air ields
• 12plorations one apidly And
1conomically
• Simple0 4ight0 le2i.le0 /ne2pensi+e
/nstruments
• ifficult for hard soil and soil containing
5ra+els
• Used up to 6 m ("anually) #$m
("echanically)
• or sandy soil this method is slow and
expensive
• ot suita.le for - large cobbles,
boulders or other o.struction which
pre+ents drilling of the hole%
-
8/18/2019 Soil Investigation Methods
9/20
A%ge& *ith Shell (o&ing
• Casing is provided in case o# wea$ strata
• %irst the casing is driven and then the auger
• Boring rig is used #or power driving &hand rig#or depth up to '( m)
• So#t roc$s are bro$en using chisel bits
• Sand pumps are used in the case o# sandy soils.
-
8/18/2019 Soil Investigation Methods
10/20
Advantages Limitations
• "a7ing deep .ore
• Useful when depth of e2ploration
is small
• /n+estigations are done 8uite
rapidly and economically .y
auger .oring
• Used up to $ m ("anually) 'm
("echanically)
• Auger .oring is that the soil
sample are highly distur.ed
• /ts .ecome difficult to locate the
e2act changes in the soil strata
-
8/18/2019 Soil Investigation Methods
11/20
+ash Bo&ing• *ere #irst an open hole is #ormed on the ground so
that the soil sampling or roc$ drilling operation
can be done below the hole.• The hole is advanced by chopping and twistingaction o# the light bit.
• Cutting is done by #orced water and water +et
under pressure through the rods operated insidethe hole.
• a pipe o# (cm diameter is held vertically and #illed with water using hori,ontal lever arrangement and
-
8/18/2019 Soil Investigation Methods
12/20
• by the process o# suction and application o#pressure soil slurry comes out o# the tube andpipe goes down.
• This can be done up to a depth o# m 01m
&e2cluding the depth o# hole already #ormed be#orehand)
• 3ust by noting the change o# colour o# soilcoming out with the change o# soil character can
be identi#ied by any e2perienced person.
-
8/18/2019 Soil Investigation Methods
13/20
Advantage Limitations
• the use o# ine2pensive andeasily portable handling anddrilling e4uipment
• 9he soil immediately .elow thehole remains relati+ely un-
distur.ed
• &oring can .e used in most typeof soil
• 9he accurate identification of soilstrata is difficult due to mi2ing ofthe material as they are carried tothe surface%
•9he method is unaccepta.le foro.taining soil samples%
• not suitable #or very so#t soil#ine to medium grainedcohesionless soil and incemented soil
-
8/18/2019 Soil Investigation Methods
14/20
-
8/18/2019 Soil Investigation Methods
15/20
Rota&) !&illing
• use#ul in case o# highly resistant strata• #inding out the roc$ strata and also to assess the
4uality o# roc$s #rom crac$s #issures and +oints. andcan be used in sands and silts
• There are two #orms o# rotary drilling open-holedrilling and core drilling.
• Open-hole drilling uses a cutting bit to brea$ downall the material within the diameter o# the hole.
• 5n core drilling a diamond or tungsten bit cuts ahole in the roc$ and an intact core enters the barrel
which is then removed as a sample.
-
8/18/2019 Soil Investigation Methods
16/20
• the bore holes are advanced in depth by rotarypercussion method
• A heavy string o# the drill rod is used #or cho$ingaction.
• The bro$en roc$ or soil #ragments are removed bycirculating water or drilling mud pumped throughthe drill rods and bit up through the bore hole #rom which it is collected in a settling tan$ #orrecirculation.
-
8/18/2019 Soil Investigation Methods
17/20
• %or deep holes and unstable soils drilling #luids are
use#ul as they serve to stabili,e the bore hole
• rilling mud is slurry o# bentonite in water
• The drilling #luid causes stabili,ing e##ect to the bore
hole partly due to higher speci#ic gravity as compared with water and partly due to #ormation o# mud ca$eon the sides o# the hole.
• As the stabili,ing e##ect is imparted by these drilling
#luids no casing is re4uired i# drilling #luid is used.
Need further reading- Bentonite slurry
-
8/18/2019 Soil Investigation Methods
18/20
$e&,%ssion !&illing
• 5n case o# hard soils or so#t roc$ auger boring or wash boring cannot be employed. %or such
strata percussion drilling is usually adopted.
• 5s used to construct large diameter bore holes inloose so#t hard roc$y and boulder-gravel-sand
clay&mi2ed ) #ormations.• 5s most suited to drill in stratum where large boulders in abundance are encountered atdi##erent depths.
-
8/18/2019 Soil Investigation Methods
19/20
• advancement o# hole is done by alternatively li#ting anddropping a heavy drilling bit which is attached to the lower end
o# the drilling bit which is attached to the cable. Addition o# sandincreases the cutting action o# the drilling bit in clays. Whereas when coarse cohesionless soil is encountered clay might have to be added to increase the carrying capacity o# slurry.
• A#ter the carrying capacity o# the soil is reached churn bit isremoved and the slurry is removed using bailers and sandpumps.
• Change in soil character is identi#ied by the composition o# the
outgoing slurry.
• The stro$e o# bit varies according to the ground condition.6enerally it is 7(-011cm in depth with rate o# 8(-91 drops/min.
-
8/18/2019 Soil Investigation Methods
20/20
Advantage Limitations
•5t can be used in most o# thesoils and roc$s and can drillany material
• 5t is not economical #or hole o#diameter less than 01cm
•the material at the bottom o#the hole is disturbed by heavy blows o# the chisel and hence itis not possible to get good4uality undisturbed samples
•
5t cannot detect thin strata as well.
top related