- Example I Provide My Assignment The Type Of Piling System Questi 1 (379.26 KiB) Viewed 31 times
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My assignment:
The type of piling system:
- Example I Provide My Assignment The Type Of Piling System Questi 3 (318.74 KiB) Viewed 31 times
- Example I Provide My Assignment The Type Of Piling System Questi 4 (68.95 KiB) Viewed 31 times
- Example I Provide My Assignment The Type Of Piling System Questi 5 (126.17 KiB) Viewed 31 times
system suitable for the proposed building.
Construction Technology 2 Past Exam Paper Answers By Man Wong Selection of Piles With reference to the Borehole record as shown in Table 1, analyze and propose a suitable Piling System for a 40-storeyed building to be built in a new developing area. [13M) Reduce Total Core Soil Description Depth RQD% Grade Level Recovery % 0.00 7.3 2.8 6.9 10.6 Start Wash boring - No sample Medium dense, Brown, Silty fine to Course SAND with a little fine gravel (FILL) Medium dense, Yellowish brown, Slightly clayed silty medium to fine SAND (RESIDUAL SOIL) Extremely weak. Light pinkish grey & locally spotted brown, completely decomposed, fine grained GRANITE, cobbles and occasional boulders of weathered granite. GRADE II/IV. N=50 at 15.00 60 V 17.4 N=110 at 20.00 Very weak, light pinkish grey & locally spotted brown, completely decomposed, fine grained GRANITE (very dense, silty medium to fine and with a little fine gravel). 65 V/IV N>200 at 22.9 23.8 III Moderately strong, pinkish grey, 25.00 moderately decomposed, fine grained 85 93 28.80 GRANITE Strong, pinkish grey, slightly decomposed, 29.40 -22.1 100 98 II fine grained GRANITE Table 1 Summary of borehole records for a proposed site Remarks: 1. The depth shown is NOT to Scale. 2. The depth shown indicates the depth of the bore hole. 3. Reduced level shown is the existing ground level where drilling starts and ends.
. Ans. 40-storeys building ✓ Heavy loading ✓ Large diameter bored piles, H-piles or high strength composite piles New developing area ✓ No noise restriction Driven H-piles Soil gives good friction at about 23m (N>200) ✓ Bored pile and H piles are suitable Grade 3 rock at about 30m below ground level ✓ An economical depth for bored pile ✓ . .. H-piles Fast in construction as noise restriction is not on concerned Soil gives good friction which N>200 at about 23m deep Discuss and propose a suitable piling system for a 45-story commercial building to be built on site with the following site investigation information: [20M] Granite rock of Grade Il to Grade Ill properties was found at an average depth of 25m to 30m below the existing ground level. Water table level is 6m below the existing ground level. ✓ Ans. 40-storey building ✓ Heavy loading Large diameter bored piles, H-piles or high strength composite piles Commercial building ✓ Noise restriction ✓ Driven piles not suitable (except hydraulic jack H-pile) Grade 3 rock at about 30m below ground level An economical depth for bored pile Water table level at 6 meter below ✓ Steel casing should be used to exclude water ✓ Heavy loading and noise restriction is a concern which driven H-pile cannot be used. As Grade 3 rock at about 30m below ground level which is an economical depth for bored pile Therefore, large diameter bored piles can be used.
up to 600 Types of Pile Classification Shaft / Shape / Length / Diameter / Max allowable Extension Remarks Materials Depth (m) Size (mm) axial loads of piles (kN) Precast Large square, 20 250 to 450 1000 coupling, not suitable for ground reinforced displacement hexagonal, splicing, with boulders or concrete piles circular, welding corestomes triangular and H shape Prestressed Large- closed-ended 20 400 - 600 3000 welding Not common but for concrete tubular displacement tubular marine work - less piles permeable; up to 75 |MPа Closed-ended Large- box-section, steel Fill with concrete as steel tubular displacement tubular (more appropriate piles common) Driven cast-in- Large formed by steel 30 1400 NA Top or bottom-driven place concrete displacement tube and fill by (can be enlarged) piles concrete Steel H-piles Samll- H-pile More than 283 kg/m 3000 welding very common in HK displacement 50 Open-ended Samll- Open-ended 50 275-2000 7000 welding marine structure steel tubular displacement tubular steel piles piles Small-diameter Replacement circular 30 300-600 1000 NA Pakt-in-Place (PIP) bored piles 300-700 of 30m long; boulder Large-diameter Replacement circular 80 1000-2500 36 000 NA for tall building with bored piles very heavy loads; can form bell out, usually end bearing in HK Hand-dug Replacement circular 1500-2500 25 000 NA high accident rate; the caissons (can be use of caissons 7000 - 10 should be avoided; 000) use for steeply-sloping and restricted sites Barrettes Special - rectangular bored 80 800 x 2200; Very large - NA Large skin friction; Replacement piles (very similar 1200 x depend on very heavy loaded to diaphragm panel size building walls) Mini-piles Special - circular Typically 100 - 250 700 - 1000 usually friction piles Replacement 60 for site with difficult access and limited headroom, eg underpinning Summary of characteristics of piles commonly used in Hong Kong SAR 2800
Project Information Height of building Project A 25 floors, 78m high, with 2-level Basement (8m deep) 750 m2 Site Area Usage Residential Location Urban area Surrounding condition Site surrounded by new buildings Terrain 2 levelled platform
頁面 22 2 Summary of Borehole Logs Soil Description Depth Total core recovery% Grade Start 0 Wash boring - no sample 6.5 Medium dense, brown, silty fine to course SAND with a little fine gravel (FILL) N=60 at 18.5 20.3 Medium dense, yellowish brown, slightly clayed silty medium to fine SAND (RESIDUAL SOIL) 28.3 Extremely weak. Light pinkish grey & locally spotted brown, completely decomposed, fine grained GRANITE, cobbles and occasional boulders of weathered granite. Grade II/IV. N=95 at 35.4 55 V 36.2 Moderately strong, pinkish grey, moderately decomposed, fine grained GRANITE 38.3 85 III 60 VIV Very weak, light pinkish grey & locally spotted brown, N=150 at 45.40 completely decomposed, fine grained GRANITE (very dense, silty medium to fine sand with a little fine gravel). N>200 at 50.45 53.2 70 VI Weak, light pinkish grey & locally spotted brown, completely decomposed, fine grained GRANITE (very dense, silty medium to fine sand with a little fine gravel). 64.9 Moderately strong, pinkish grey, moderately decomposed, fine grained GRANITE 85 III 72.3 95 II Strong, pinkish grey, slightly decomposed, fine grained GRANITE 80.3 End Remarks: Ground level is at +4.2m The depths shown indicate the bottom level of the section. For example: the depth of the last section is at a depth of 80.3m