TECHNICAL NOTE 1 - Stone Column
ITEM 203.99870017 – STONE COLUMNS - BOTTOM FEED - VIBRO-DISPLACEMENT
(DRY) METHOD
Page 1 of 3 11/13/00 09/01/05
12/10/03
DESCRIPTION
This work shall consist of installing stone columns using a bottom feed vibro-displacement (dry)
method in accordance with these specifications and in reasonably close conformity with the lines
and dimensions shown on the plan or established in writing by the Engineer.
This work shall be accomplished by a Contractor experienced and properly equipped in the
installation of stone columns by the dry method. The Contractor shall submit evidence of having
satisfactorily installed stone columns on at least three projects to the Director of the Geotechnical
Engineering Bureau, who will evaluate this experience for approval or disapproval. This
submission shall identify the client, size and dates of projects, list of equipment, method of
installation, and key personnel from those projects to be assigned to this project.
MATERIALS
Backfill used in the stone columns shall be crushed stone meeting the requirements of §703-02
Coarse Aggregate. The gradation shall conform to Size Designation 2, as shown in Table 703-4,
or an approved equal. At least one month prior to commencement of the stone column
installation, the Contractor shall submit to the Department a minimum of three 50-pound bags of
crushed stone proposed for this Backfill Stone for testing to determine specific gravity, and loose
and compacted density.
CONSTRUCTION DETAILS
A. Equipment. The Contractor’s equipment shall be capable of producing and/or complying
with the following:
1. Contain a motor to drive an eccentric mass at a frequency of 1600 to 3000 RPM which
shall be capable of generating at least 100 hp and 20 tons of centrifugal force.
2. Produce a double amplitude (peak to peak measurement) of the probe tip a minimum of
0.6 inches in the horizontal direction when the probe is in a freely suspended position.
3. The probe and follower tubes shall be of sufficient length to provide stone columns
having a maximum length of 35 feet and have visible external markings at 1.0 foot
increments to enable measurement of penetration and re-penetration depths.
4. Provide for supplying compressed air to minimize clogging within the stone delivery pipe
and to assist in the placement of the backfill stone.
5. Be capable of compacting the backfill stone and forcing the stone radially into the
surrounding in-situ soil by means of displacement in combination with vibration.
6. Be capable of constructing stone columns in a manner such that dissipation of vibratory
energy to the surrounding soil occurs mainly from the lower portion of the probe.
7. Be capable of constructing stone columns in a manner such that the probe remains in the
unbackfilled part of the hole at all times.
ITEM 203.99870017 – STONE COLUMNS - BOTTOM FEED - VIBRO-DISPLACEMENT
(DRY) METHOD
Page 2 of 3 11/13/00 09/01/05
12/10/03
B. Stone Column Construction
1. The Drainage Blanket shown on the plans shall be placed before installing any stone
columns.
2. The sequence of stone column installation shall be in accordance with the plans unless
otherwise directed by the Engineer. The upper dense soil may be augered to a point
where penetration of the remaining soil may be achieved by the probe tip to the required
column depth. The depth of pre-augering shall be approved by the Engineer. Soil
removed by augering shall be disposed of as approved by the Engineer. Stone backfill
shall be placed from the bottom up to the working surface in increments not exceeding
4.0 feet in depth. The use of water during installation will not be allowed.
3. Prior to the installation of production stone columns, the Contractor shall install five test
columns within the stone column layout pattern shown on the plans. Each specific test
column location shall be selected by the Engineer. The purpose of these test columns is
to establish optimum, site-specific, stone column installation and construction control
procedures and power consumption to be used in the production work.
4. Stone columns shall be installed so that each completed column will be continuous
throughout its length with an average effective diameter of 3.5 feet for every 2 foot
increment of depth. If the average effective diameter of a 2 foot increment of depth,
either during the installation of a test column or a subsequent production column, is less
than 3.5 feet for three or more measurements, and the workmanship, power consumption,
and materials are otherwise acceptable, the Contractor shall be allowed to complete the
column being installed. The Contractor shall then cease all further stone column
installation operations in the immediate area of this stone column to allow the Engineer to
determine if it is necessary to adjust the column size and pattern spacing, and to what
extent. The time period for the Engineer’s assessment will not exceed one full work day.
5. No stone column shall be accepted for payment that has an average effective diameter
less than 3.0 feet for any 2 foot increment unless approved by the Engineer. The
Engineer’s decision will be based on a review of the Contractor’s installation procedures
including power consumption used for installing the stone column.
6. The average effective stone column diameter shall be calculated by the Contractor using
the Department’s assigned in-place density of the stone and the weight of stone used to
fill a given length of the hole. For calculation of constructed column diameter, the
assigned in-place density of stone columns shall be equal to the density corresponding to
95% of the laboratory relative density determined by the Department.
7. The Engineer may also require that stone column installation work cease if State installed
instrumentation at this site indicates potential or actual slope movement. In this case, the
Engineer will determine if, and to what extent, the sequence and rate of stone column
installation is to be modified.
ITEM 203.99870017 – STONE COLUMNS - BOTTOM FEED - VIBRO-DISPLACEMENT
(DRY) METHOD
Page 3 of 3 11/13/00 09/01/05
12/10/03
C. Subsurface Obstructions. In the event that subsurface obstructions encountered during
construction of a stone column cannot be penetrated with reasonable effort, the stone column
shall be constructed following the specified procedures from the obstruction to the surface of the
drainage blanket. The Engineer may direct the construction of a replacement stone column at
another location.
D. Construction Records. The Contractor shall provide competent and qualified personnel to
prepare and furnish to the Engineer, daily recorded logs of the following data:
1. Stone column reference number.
2. Elevation of top and bottom of each stone column.
3. Peak power dissipation from the probe, by instrument reading, for each one foot of stone
column, or each increment of stone charge added.
4. Volume measurement and calculated weight of the total amount of loose stone used for
each column.
5. Time to penetrate and time to form each stone column.
6. The average effective diameter of every 2 foot of increment in depth for columns. This
information shall be provided to the Engineer as work progresses as well as at the end of
the work day.
7. Details of obstructions, delays, notations of artesian flow from stone columns and any
other unusual ground conditions.
8. Pre-augered depth, if any, for each stone column.
All records shall be of form and content to the satisfaction of the Engineer.
METHOD OF MEASUREMENT
This work will be measured as the number of linear feet of stone columns, including test
columns and obstructed stone columns, satisfactorily completed in-place in accordance with the
contract documents and as directed by the Engineer. Measurement will be from the bottom of
each column to the top of the working surface. Measurement will be to the nearest 0.5 foot.
BASIS OF PAYMENT
The unit price bid shall include the cost of furnishing all labor, mobilization and utilization of all
equipment and material for developing and backfilling stone column holes with backfill stone,
providing records and logs as necessary to satisfactorily complete the work, and for removal and
disposal of any excavated or augered material from stone column holes.
PROJEK LEBUHRAYA PANTAI TIMUR-JKR
2. Panjang Lebuhraya ialah 184 kilometer. 120 km dibawah seliaan JKR dan 64 km dibawah seliaan LLM. Mempunyai 4 lorong dua hala, R&R, Lay By, Plaza Toll dan 10 persimpangan bertetingkat.
3. Terdapat 16 Pakej dibawah seliaan JKR iaitu 1A, 1B, 1C, 2, 3, 4, 5a, 5b, 6, 7, 8, 9A, 9B, 9C, 11 dan 12. pakej 10 dibawah seliaan LLM.
4.Pakej 1a- actual 53.9%, schd 74.1%
5.Pakej 1b - actual 59.0%, schd 71.9%
6.Jambatan 62, ES 21, VBC 48. BC, 124 dan PC 334.
RETENDER PROCESS
Before I proceed with more explanation, lets me brief some of process and documents needed during the retendering process. The documents must be prepared are the Document for Tender and Table Tender Document. (Actually this are the same documents, only the little bit difference at the front cover). This document divided to 3 sections, thera are Section 1, Section 2 and Section 3. For Section 1, the main contents are with regards to contractual matters, Bill of Quantity and Metod of Measurement. Section 2 explain about the specification of the scope of works. And section 3 is a set of Tender Drawing. Tender Document will sell to contractor and TTD will be show or......To be continued......
How we prepare all the above-mentioned documents.
SENARAI TINDAKAN YANG BOLEH DIBUAT :
1
Final Joint Survey dan Measurement
Perlu dilakukan di antara pihak JKR dan kontraktor. Ia bertujuan untuk mendapatkan Kuantiti Akhir bagi kerja-kerja yang telah dilakukan oleh pihak kontraktor dan bagi peyediaan Lukisan As Built. Joint Survey perlu dilakukan pada jarak 20m interval.
2
Penyediaan As Built
i. Earthworks – perlu dinyatakan dalam lukisan kedudukan pre com level, design level dan existing ground level. Jika terdapat kawasan over cut perlu dimasukkan sekali. Update lukisan pembinaan –Cross Section Drawings.
ii. Struktur Jambatan, Sistem saliran, Culvert, Turfing dan semua skop kerja yang terlibat – Tanda dan lorekkan bahagian yang telah dibuat beserta ukuran atau level dalam lukisan pembinaan.
3
Material on Site
- Senaraikan bahan-bahan yang perlu disimpan atau dipulangkan kembali kepada pihak kontraktor. Perlu dinyatakan bilangan, keadaan bahan dan disertakan gambar.
- Perlu disediakan tempat penyimpanan bagi mana-mana bahan yang hendak disimpan.
4
NCR
Pastikan semua NCR telah ditutup.
5
Perolehan Melalui Kontrak
Pastikan segala senarai item yang diterima dipulangkan dan ditandatangani oleh pihak kontraktor. Rujuk pada senarai inventory.
6
Repair/Remedial Works
Perlu disenaraikan mana-mana skop kerja yang telah siap yang memerlukan kerja-kerja pembaikan seperti slope failure, erosion, kerosakan pada struktur dan sebagainya.
7
Penyediaan Dokumen Retender (Section 1, 2 and 3)
a. Bills of Quantity
- Senaraikan item-item yang perlu dimasukkan dalam BQ. (BQ item ikut Dokumen Kontrak Asal)
- Dapatkan baki kuantiti berdasarkan kerja-kerja yang telah siap ditapak.
- Setiap maklumat dalam BQ perlu seiring dengan maklumat yang terdapat dalam Lukisan dan MOM.
- Sila rujuk Lampiran B bagi contoh BQ bagi Pakej yang telah di retender.
- Setiap kuantiti yang dimasukkan perlu disediakan Taking Off dan disahkan oleh pihak di tapak.
- Sebarang pertambahan kuantiti perlu ada justifikasi (evidence), Taking Off dan gambar tapak sebagai sokongan.
-
b. Method Of Measurement
- Turutan no. dalam MOM perlu seiring dengan BQ.
- Terdapat item dalam MOM yang perlu disemak terutamanya melibatkan kerja-kerja yang sebahagiannya siap, perubahan dari segi unit dan perubahan dan pertambahan skop.
c. Lukisan
- Lukisan yang perlu disediakan ialah Lukian Tender (A3 size) dan Lukisan untuk TTD (A1 size).
- Di antara maklumat yang perlu di masukkan dalam Lukisan Tender :
i. Cross Section and Plan and Longitudinal Profile
- Finished Road Level, Existing Ground Level and Distance.
- Perlu di masukkan Nota : Existing Ground Level to be Confirmed on Site by Registered Licensed Surveyor.
ii. Drainage Layout dan Culvert Layout
- Lukisan perlu dikemaskini berdasarkan kapada keadaan semasa di tapak. Mana skop kerja yang telah siap perlu di omit.
- Bagi skop kerja culvert yang telah disiapkan perlu dilorekkan dan jadual culvert (culvert schedule) perlu dikemaskini mengikut keadaan sebenar di tapak.
iii. Struktur
- Tanda dan lorekkan bahagian yang telah dibuat beserta ukuran atau level.
- Setiap maklumat dalam lukisan perlu seiring dengan BQ.
Gambar/Photo keadaan tapak perlu diambil pada lokasi/kedudukan yang sama pada setiap minggu untuk menunjukkan keadaan tapak yang mungkin berubah/rosak akibat terbiar begitu lama atau berlaku vandalism/kecurian.
AUTO CADD
1. File-plot-pilih printer-paper size-centre the plot-fit to paper-pada what to plot, pilh windiw dan select mana nak print.
Scale dan cari area gunak auto cadd
1. Scale kan dulu drawing tersebut
-sc-pick point-r-masukkan jarak asal-masukkan scale sebenar-pl-sambungkan semua-Li
2. One more method to change a scale...example: 1:400 to 1:1 :-
-sc-specify base point (click kat mana2)-masukkan scale 400/1000 = 2/5 enter...so dah jadi scale 1:1 ...ukur jarak guna dmension mesti dapat jarak sebenarnya. then start kira area guna kaedah no.1.
Cross Section
1. Nak start buat cross section, kena ada maklumat proposed road level, ogl data and distance. Biasanya guna software msroad.
2.Ada satu kes di mana cross section perlu disiapkan untuk retender but when checked as built survey done by contractor scale tak betul but data existing ground level valid.(datum tak boleh pakai sebab nak guna datum pada construction dwg) So what to do...nak pulangkan balik ....lambat lagi leeeee...so kena buat sendiri.........Bawah ni step dia...
- dapatkan soft copy cross section connstruction dwg....tukar scale kepada 1:1...
- delete data ogl dalam cross sect. construction dwg ....then masukkan data as built or EGL...before masukkan data EGL, dapat jarak sebenar ketinggian atau level sebenar keadaan di tapak iaitu aras datum pada construction drawing tolak dengan EGL/as-built. pada setiap distance. Dah dapat level sebenar masukkan nilai ketinggian tersebut kedalam cross sect. yang hendak di buat. Caranya ialah -line-pick point dekat jarak dia-masukkan nilai ketinggian dia iaitu datum tolak EGL-enter 2kali....then sambungkan dia..
Nak Cari Area at Cross Section and Keluarkan Coordinat X,Y
1. Check scale, make sure scale 1:1
2. Draw line. Starting point is from as built level at centre of the cross section and tarik ke bawah ....dan masukkan level as built level/Existing ground level. Then enter 2x.
3. Set UCS - type UCS-and pick kat hujung line yang baru buat tadi. Then enter.
4. Set Boundry - BO - pick kat centre of the area
5. List (Li) - enter
6. Copy list to excel and nak sort ikut column, go to data-text to column.....
Final Quantity
2. Mengapa masalah-masalah yang disebut di atas kerap berlaku dalam pasukan pembinaan(baik kontraktor, wakil client dan perunding)? Daripada pemerhatian dan pengalaman, di antara punca-puncanya ialah kurangnya semangat berpasukan ynag baik di dalam organisasi dalaman mahupun di luar, kurang pengalaman tetapi malu bertanya ataupun ego, attitude yang tidak baik, tiada kejujuran, ketua yang lemah di mana tidak mampu menangani organisasi di bawah kendaliannya, tidak tegas, malas, suka mengelak, tidak faham berkenaan sistem dan prosedur yang telah sediada dan sebagainya yang boleh menyumbang berlakunya kepincangan kemudian hari terutamanya berkaitan perkara yang dibincangkan di atas.
3. Bagaiman kita sebagai salah seorang dari pasukan projek ingin mengatasi masalah ini, jangan hanya pandai bercakap je tetapi masalahnya tetap sama....................................
JAMBATAN
2. Perkara pertama yang perlu dibuat ialah setting out of piling point. Ini perlu dibuat dengan tepat, kerana sekiranya berlakunya kesilapan ia akan memberi kesan di antaranya kepada kedudukan pile cap, kedudukan abt wall di mana jarak antara abt A dan B mungkin terpendek atau terpanjang dan mengakibatkan beam tidak dapat di launch. Sekiranya kedudukan jambatan skew, lebih perhatian perlu di berikan.
3.Terdapat kes yang berlaku di mana setelah ballast wall disiapkan, didapati bucu beam terkena bahagian ballast wall (jambatan skew).Untuk mengelakkan kes ini berlaku, setiap peringkat pembinaan seperti pile cap, abt wall dan ballast wall perlu disemak kedudukannya sebelum dibina.
4. Di sini saya ingin berkongsi satu kes di mana kerja piling telah dibuat dan didapati beam mungkin tidak boleh dipasang sekiranya mengambil kira kedudukan piling yang telah dibuat. Oleh itu langkah yang boleh dibuat untuk memastikan beam boleh dipasang ialah meninggikan kedudukan salah satu pile cap ataupun melakukan perubahan terhadap kedudukan ballast wall.
5. Terdapat beberapa jenis cerucuk yang digunakan dalam pembinaan jambatan. Di antaranya ialah spun pile dan bore pile. Untuk kerja-kerja spun pile terdapat beberapa perkara yang perlu diawasi semasa kerja-kerja piling dijalankan. Contohnya seperti point, verticality (not more 75mm), jointing, kalau ada banyak pile, kedudukan mana yang perlu di drive dulu dsb.
6. Jenis-jenis ujian cerucuk yang perlu dilakukan sebelum, semasa dan selepas. Test drive, nak tahu roughly tentang kedalaman pile dan jenis kombinasi pile yang akan digunakan. Load test, twice working load. PDA test.......