bored pile installation

R.Karlinasari

Mobilisasi Mudah

Tidak mengganggu lingkungan dengan

getaran yang dapat merusak/ retak

dinding bangunan sekitar proyek.

Pengoperasian alat sederhana.

Memenuhi syarat teknik dan spesifikasi

bangunan.

Dia 200 mm. Dia 300 mm. Dia 400 mm Dia 600 mm Dia 800 mm. Dia 1000 mm Dia 1200 mm Dia 1500 mm Dia 2500 mm, etc

Jenis mata bor yang di digunakan ada beberapamacam sesuai dengan kondisi tanah yang akan di borantara lain :

Mata bor cross bit/ palang untuk segala jenis tanah. Mata bor coring yang terbuat dari pipa sesuai

dengan diameter lubang dengan di beri batu widya/ mata intan pada ujungnya untuk tanah cadas/cemented

Mata bor ulir untuk tanah berkerikil atau berpasir.

.

FHWA-NHI-10-016 4 - General Construction Methods

Drilled Shafts Manual 4-13 May 2010

Setting alat di titik pertama dan pembuatan bak sirkulasi.

Setelah hal tersebut sudah siap maka pengeboran di lakukan dengan rotary drilling dynamo 20 PK, Pipa bor 3 meteran dia 2,5 inchi dan mata bor sesuai besar lubang yang di inginkan.

Proses pengeboran di lakukan dengan memasukkan air dari bak sirkulasi yang dipompa dengan menggunakan pompa sedot 3 inchi ke dalam watersifel yang di alirkanke dalam pipa bor 2,5 “ kemudian air akan ke luar pada ujung mata bor, air di gunakanuntuk mempermudah proses pengeboran sebagai pelunak tanah.

Bila lapisan tanah yang di bor adalah pasir , maka air di ganti dengan cairan bentonite.

Setelah lubang di bor sesuai dengan design atau mencapai tanah keras maka lubangbor di bersihkan dari lumpur pekat atau gumpalan – gumpalan tanah denganmenggunakan tabung pembersih.

Setelah lubang bersih maka besi tulangan dapat di masukkan ke dalam lubang denganhati -hati dan di beri cetakan semen pada setiap sisi tulangan untuk menjaga posisitulangan tidak bersentuhan pada dinding tanah.

Kemudian proses pengecoran beton slump 16 – 18 cm ( sesuai dengan prosedurpengecoran bored pile) dapat di lakukan dengan terlebih dahulu memasukkan pipatremi.

The dry method (Metode kering)The casing method (Metode casing)The wet method (Metode basah)



Dry hole construction represents the most favorable conditions for economical use of drilled shafts.

The dry method is applicable to soil and rock that is above the water table and that will not cave or slump when the hole is drilled to its full depth during the period required for installation of the drilled shaft.

A homogeneous, stiff clay can often be drilled in this manner, and sometimes homogeneous stiff clay can be drilled to moderate depths (up to 50 ft) using the dry method regardless of the long term groundwater levels because of the extremely low hydraulic conductivity of the soil.

The dry method can be employed in some instances with sands above the water table if the sands contain some cementation or cohesive material, or if they will stand for a period of time because of apparent cohesion.

This behavior generally cannot be predicted unless there is prior experience with the specific formation being excavated or full-sized test excavations have been made during site characterization.



The construction process with a dry hole :

a) The shaft is excavated using augers which will likely have teeth to break

up the soil.

b) The base is cleaned using a bucket or flat bottom tool to remove loose

debris and possibly any small amount of water.

c) In most projects, a full length reinforcing cage is placed.

d) The concrete is placed using a drop chute or centering device.



Pelaksanaan pengeboranpada lokasi pasir keringtersementasi.

Peletakan tulangan yang dilapisi “Kaki” ke dalamlubang bor



The casing method is applicable to sites where soil conditions are

such that caving or excessive soil or rock deformation can occur

when a shaft is excavated.

Casing can also be used to extend the shaft excavation through

water or permeable strata to reach a dry, stable formation.

Unless the bearing formation into which the casing is sealed is

stable and dry, it will not be possible to use the casing method

alone without the addition of drilling fluid or water.

Installation of casing is generally accomplished in one of three ways : a) 1st Method : Excavate an oversized hole using the dry method, then

place the casing into the hole. This method is suitable only for construction in soils that are generally dry or have slow seepage and that will remain stable for the period of time required to advance the hole to the more stable bearing stratum.

b) 2nd Method : Excavate an oversized hole through the shallow permeable strata using a drilling fluid, then place and advance the casing into the bearing stratum. After the casing is sealed into the underlying more stable stratum, the drilling fluid can be removed from inside the casing and the hole advanced to the final tip elevation in the dry.

c) 3rd Method : Advance the casing through the shallow permeable strata and into the bearing formation ahead of the shaft excavation, and then excavate within the casing in the dry. With this approach, casing may be driven using impact or vibratory hammers or using a casing oscillator or rotator with sufficient torque and downward force to advance the casing through the soil ahead of the excavation. Even larger upward force may be required to pull the casing during concrete placement.

Pemasangan casing pada kondisi tanah kering/bagus denganVibro hammer dan twisting bar



Sebuah Oscillator untuk mendorong casing ke dalam lapisan tanah



hb

hw

Muka Air Tanah

Pipa Tremie

? b . hb

? w. hw

Casing

Jika misalkan hw pada kedalaman -15 m, Dasar Bore adalah - 45 meter Maka pipa Tremie harus :

1/10 * (45-15) m = 3 meter

Jika dasar bore 45 meter, maka pipa tremie harus padakedalaman 42 meter ( minimal)

SF = hb/hw = 1/10hb = 1/10 hw

Jadi ϒb. hb > ϒw. hw

When soil conditions do not permit dewatering of the shaft excavation, the excavation and concrete placement operations must be completed “in the wet”. With this method, the hole is kept filled with afluid during the entire operation of drilling the hole and placing the reinforcing and concrete. The drilling fluid may consist of water if the hole is stable against collapse, or a prepared slurry designed to maintain stability of the hole.

Several circumstances in which construction in the wet would be used are described below : The shaft is founded in a sand or permeable stratum which will collapse or become

unstable during excavation. A drilling slurry is required to maintain the stability of the hole and prevent inflow of groundwater.

The shaft is founded in a stable formation, but extends through caving or water-bearing soils of such depth and thickness that the required casing would be very long and difficult to handle. A drilling slurry is required to maintain the stability of the hole and prevent inflow of groundwater.

A full length casing is driven in advance of the excavation, but the soil or rock conditions at the base are permeable and do not permit dewatering. Because the full length casing provides a stable hole, plain water can often be used instead of slurry.

The hole is cased to a stratum of rock which is stable, but groundwater inflow is greater than 12 inches per hour. In this case, the hole is kept filled with water to prevent inflow during concrete placement.



Gambar 9. Proses Pelaksanaan bore pile dengan metode basah

When the pore sizes in the formation being excavated are large (as in gravelly soils

or poorly graded coarse sands) the filter cake may be replaced by a deep zone of

clay platelet deposition within the pores that may or may not be effective in

producing a stable borehole.

bored pile installation

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