presentation spt

7/27/2019 Presentation SPT

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STANDARD PENETRATION TEST


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WHAT IS SPT?

Dynamic penetration test carried out using a

standard procedure which described in BS

1377-9: 1990

As an indicator of the density and

compressibility of granular


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HOW SPT WORK?

Use a thick-walled sample tube.

Driven into the ground at the bottom of the

borehole by blows

Blow count gives an indication of the density of

the ground

the small sample that is recovered will havesuffered some disturbance but can normally be

used for identification purposes.


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WHY USED SPT?

To provide an indication of the relative densityof granular deposits, such

as sands and gravels from which it is virtually

impossible to obtain undisturbed samples.

simple and inexpensive


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CONE PENETRATION TEST


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CONE PENETRATION TEST CAN IN PRINCIPLE BE

USED TO EVALUATE:

type of soil

soil density and in-situ stress conditions

shear strength parameters. the liquid limit and plastic limit of soil sample

material properties


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HOW CPT WORK?

The test is performed using a cylindrical penetrometerwith a conical tip (cone) penetrating the ground at aconstant rate.

During the penetration, the forces on the cone and thefriction sleeve are measured.

The measurements are carried out using electronictransfer and data logging, with a measurement frequencythat can secure detailed information about the soilconditions.

The test method consists of pushing an instrumentedcone, with the tip facing down, into the ground at acontrolled rate (controlled between 1.5 -2.5 cm/saccepted).


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HOW CPT WORK?


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EQUIPMENT OF CPT

A cylindrical probe with a con-shaped tip with

different sensors that allow continuous

measurement of soil strength and

characteristics.


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TRIAL PIT


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TRIAL PITAn excavation of ground in order to study or

sample the composition and structure of the

subsurface.

Expensive, take time to excavate and are not

always as informative as expected.


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Dug during a site investigation, a soil survey

or a geological survey.

Dug before the construction. (to determine

the geology and the water table of that site)


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Starting size for a pit depends on the depth it

is to be sunk

Decide the depth and information to be

sought and whether other means before start

the trial pit.

1 and 4 meter deep.

Dug by hand or using a mechanical digger.


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Can be extended into tranches to trance any

particular feature. (very efficient and

economical)

Rapid check on the condition of the ground

can be check if there is no side support.

(unsafe but the technician can prepare a

visual log of strata)


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Tube samples can be driven into the floor of

the pit using a jarring link drill rods.


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In-situ-testing also can be carried out. (must

do fast before the pits collapse)

Vane Shear Strength Test


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Since open pits can be hazard to others, it is

encouraged to backfill pits as soon as

possible.

There is an advantage if we leaving pits

fenced, shored and open. ( allow the

excavated surface to partially dry)


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ADVANTAGES DISADVANTAGES

Preferred for cohesive soiland soft rock

Showing clear land strata to

facilitate rough inspections

Easy dug / excavated usingdiggers

Depth is limited Deeper excavation will

require the human energy


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TRIAL PITTING SAFETY GUIDANCEA competent person must supervise the work

and operatives must be given clear

instructions on working safely when near

excavations.

If there is a risk of contact with buried

services then up-to-date utility drawings must

be consulted prior to carrying out anyground-works.


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A cable avoidance tool should be used to

locate the buried cables and a hand dug trial

pit shall be excavated if in doubt.

The excavated sides must be prevented from

collapse either by digging a safe angle or by

shoring with timber or support systems.

Whenever possible, the workings should becovered outside work hours.


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THANK YOU

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NUR NADHIRAH IZYAN BINTI AZMAN 15DKA11F2049

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