USM .....what do you know about USM. USM is unwanted material at site. Its part of geotechnical scope. Normally the USM will be removed from site to the contractor own dumping area. And its depend to how severe and the depth of USM. The depth of USM and type of treatment has been stated in Construction Drawing. Some of the treatments are :
a. Remove and replace with sand and after that continue with normal filling. Normally for depth around 1.5m to 2m. To know the depth of USM do a MP test until 40 blows 3 consecetive . Do Atterberg Limit Test to get a LL, PL to confirm the material weather USM or not eventhough drawing has stated.
b. Remove and Replace with sand sometime install PVD and after that install with instrumentation such as pneumatic piezometer, settlement gauge, inclinometer and continue filling. Reading will be taken every 300mm of filling. And some cases it will be rest for 7 days before continue with next filling. After complete a filling add 1.5m surcharge and monitor settlement for six month.
c. Dynamic Replacement
TANAH HITAM
Nak bincang sikit pasal tanah hitam kat tapak.
Macama mana nak tahu dekat kawasan kita nak bina tu ada tanah hitam atau tidak (soalan ni masa belum buat apa2 lg ....kawasan tu masih hutan lagi). Untuk makluman tanah hitam ni kalau kena air ia akan jadi macam bubur. Soalan ni aku tanya sebab ada orang bertanya kenapa you tak detect tanah hitam ni masa u buat SI dulu.
Jawapannya ialah : Ia bergantung kepada jenis SI yang kita buat....kalau kita guna boring dah tentu kita tak akan dapat sample tanah hitam ni, sebabnya ia akan jadi cair. Ia kan keluar ikut air yang di gunakan semasa kerja boring dilakukan lainlah kalau kita guna Auger. Sample tanah hitam boleh diambil guna kaedah Auger ni.
SI juga boleh dilkukan pada setiap 500m interval di bahagian tengah alignment jalan, bagi memastikan data-data SI betul-betul mewakili maklumat di tapak.
Macama mana nak tahu dekat kawasan kita nak bina tu ada tanah hitam atau tidak (soalan ni masa belum buat apa2 lg ....kawasan tu masih hutan lagi). Untuk makluman tanah hitam ni kalau kena air ia akan jadi macam bubur. Soalan ni aku tanya sebab ada orang bertanya kenapa you tak detect tanah hitam ni masa u buat SI dulu.
Jawapannya ialah : Ia bergantung kepada jenis SI yang kita buat....kalau kita guna boring dah tentu kita tak akan dapat sample tanah hitam ni, sebabnya ia akan jadi cair. Ia kan keluar ikut air yang di gunakan semasa kerja boring dilakukan lainlah kalau kita guna Auger. Sample tanah hitam boleh diambil guna kaedah Auger ni.
SI juga boleh dilkukan pada setiap 500m interval di bahagian tengah alignment jalan, bagi memastikan data-data SI betul-betul mewakili maklumat di tapak.
SOIL INVESTIGATION
Dalam membicarakan perkara ini amatlah penting bagi kita untuk mengetahui kedudukan sebenar lokasi sebenar SI dilakukan sebelum ini dan maklumat SI berikut sebelum kita melakukan kerja-kerja pembinaan. Contohnya ialah maklumat BH - type of soil, in what depth, N value dsbnya. MP - N value and at what depth. Anda boleh summarry kan maklumat tersebut yang diperolehi daripada construction drawing. Dengan maklumat yang ada dapatlah kita mengawasi tapak dengan jaya nya , especially untuk kerja-kerja Geotechinical seperti ground treatment, kerja jambatan dsbnya.
TECHNICAL TALK -PROBLEM STATEMENT (PUNCHING SHEAR AT BC)
1. Problem Statement (Notification of Defect)
Failure (punching shear) has happened at bottom slab of BC. BC detail as below
a. General
L = 58.65 m
W = 4.3 m
H = 2.4 m
Catchment area - 13 ha
Q from catchment 4.85 m3/s and 5.36 m3/s 50 and 100 years ARI respectively
Max Q for BC - 21.7 m3/s
Thickness of wall and slab - 400mm (Concrete G20, reinforcement T20 main bar at top and Bottom
Concrete cover 50mm accept soffit 75mm.
b. Foundation
Pile bedding (200mm x 200mm RC pile)
Horizontal 1.5 m interval , tranverse 1.7 m interval
Nos of Piles - 108 no ( 3 rows)
Pile Drive to set , 12m length at N50, 2 nos 6m pile (for info 300mmx300mm RC pile and above have 12 m length)
c. Geotechnical
N value range 0-12 at 12 meter depth. Hard stratum at 12 m depth (N50). Max allowable strucral capacity of pile was 450 KN. (PDA test carried out got 900KN).
High of embankment 6.4 m, equal to 122 Kn/m2
Traffic lLoad - 20 KN/m2
2. Solution
From BC change to 2.4 mm dia. RCP (Remove failure BC)
Foundation increase from 400mm to 600mm with craddle (total hight - 1.2 m), width of foundation 4.1 m.
Piling use 200mm x 200mm RC pile 6 m length and drive up to 12 m length - 1.42 interval for tranverse, 1 m interval horizontal.
Reinforcement at bottom slab 4 layer BRC B10 (2top +2bottom)
C0ncrete G20/20 for all
Lean Concrete GH15/20
Failure (punching shear) has happened at bottom slab of BC. BC detail as below
a. General
L = 58.65 m
W = 4.3 m
H = 2.4 m
Catchment area - 13 ha
Q from catchment 4.85 m3/s and 5.36 m3/s 50 and 100 years ARI respectively
Max Q for BC - 21.7 m3/s
Thickness of wall and slab - 400mm (Concrete G20, reinforcement T20 main bar at top and Bottom
Concrete cover 50mm accept soffit 75mm.
b. Foundation
Pile bedding (200mm x 200mm RC pile)
Horizontal 1.5 m interval , tranverse 1.7 m interval
Nos of Piles - 108 no ( 3 rows)
Pile Drive to set , 12m length at N50, 2 nos 6m pile (for info 300mmx300mm RC pile and above have 12 m length)
c. Geotechnical
N value range 0-12 at 12 meter depth. Hard stratum at 12 m depth (N50). Max allowable strucral capacity of pile was 450 KN. (PDA test carried out got 900KN).
High of embankment 6.4 m, equal to 122 Kn/m2
Traffic lLoad - 20 KN/m2
2. Solution
From BC change to 2.4 mm dia. RCP (Remove failure BC)
Foundation increase from 400mm to 600mm with craddle (total hight - 1.2 m), width of foundation 4.1 m.
Piling use 200mm x 200mm RC pile 6 m length and drive up to 12 m length - 1.42 interval for tranverse, 1 m interval horizontal.
Reinforcement at bottom slab 4 layer BRC B10 (2top +2bottom)
C0ncrete G20/20 for all
Lean Concrete GH15/20
Pengiraan Peratus Pertambahan
Asal Baru
60000 100000
Therefore % pertambahan = 100000 - 60000/60000 x 100
= 67%
60000 100000
Therefore % pertambahan = 100000 - 60000/60000 x 100
= 67%
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