IS 2911 Part 1/Sec 1 : 2010Code of practice for design and construction of pile foundations - Concrete piles - Bored cast in-situ piles

IS 2911 (Part 1, Section 1) specifies the design and construction of pile foundations — concrete piles (driven cast-in-situ) — the in-situ-cast pile installed by driving a temporary steel casing or shoe into the ground, then removing the casing while concreting. Driven cast-in-situ piles are an alternative to bored piles (IS 2911 Part 1 Sec 2:2010) — used where dense / granular soil makes boring difficult.

Use IS 2911 Part 1 Section 1 for: - Granular / sandy soils where boring is unstable - Sites with high water table where bentonite slurry is impractical - Mid-load buildings (multi-storey residential, commercial) - Industrial / warehouse foundations (where vibration acceptable) - Bridge approach embankments (where access permits) - Older / brownfield sites without urban congestion (vibration OK)

Don't use for: - Urban congested sites (driving vibration damages adjacent structures) - Soft sensitive clays (driving disturbs surrounding soil; use bored) - Sites with restricted headroom (driving rigs need 15-20 m head) - Heritage / historical districts (vibration damage risk)

Driven cast-in-situ vs bored cast-in-situ (IS 2911 Part 1 Sec 2):

| Aspect | Driven (this code) | Bored (Sec 2) | |---|---|---| | Vibration | Significant; affects adjacent | Minimal | | Speed | Faster (5-10 piles/day) | Slower (2-5 piles/day) | | Cost | Lower per pile | Higher (bentonite, etc.) | | Soil suitability | Sand, gravel, hard cohesive | All soils | | Adjacent structure impact | High | Low | | Quality | Good (controlled length + diameter) | Variable (depends on operator) | | Inspection | Limited (during installation) | Better (cage + concrete visible) |

Driven cast-in-situ pile (using Franki / similar method):

1. Casing + shoe driven: temporary steel casing with closed-bottom shoe driven into ground using drop hammer / diesel hammer. 2. Driving to depth: continue until refusal OR design depth. 3. Cage lowered into casing: pre-fabricated reinforcement cage lowered through open top of casing. 4. Concrete poured into casing: concrete fills from bottom up; reinforcement embedded. 5. Casing extracted: casing pulled up incrementally; vibrated as it withdraws (compacts concrete + soil contact); concrete fills void left by casing. 6. Top finished: pile top cut to design level; rebar exposed for connection to pile cap.

Variants: - Franki pile: enlarged base by ramming additional concrete at toe (forms enlarged toe for better end bearing) - Vibrated cast-in-situ: vibratory hammer; less noise, less vibration than impact hammer - Drop-hammer driven: traditional; higher noise / vibration

Pile dimensions (typical): - Diameter: 300-600 mm (general); up to 1000 mm (heavy load) - Length: 8-20 m typical; up to 30 m for special applications - Reinforcement: 1-2 % cross-sectional area

Concrete: - Grade: M25 minimum; M30-M40 typical - Slump: 150-200 mm (for direct pour into casing) - Mix design (IS 10262:2019) with HRWR (IS 9103:1999)

Driving criteria: - Refusal: penetration < 25 mm in 10 successive blows - Set + rebound: monitored to estimate capacity (Engineering News Record formula or Hiley formula) - Recommended: ~10-25 mm penetration per blow as stop signal

Quality control: - Driving log: blows per metre, refusal, hammer type, energy - Concrete cubes: per pile (3-6 per pour) - Slump check - Pile head condition after cut-off - Integrity test (PIT) post-installation

• IS 2911 Part 1 Sec 2 — bored cast-in-situ piles (IS 2911 Part 1 Sec 2:2010).
• IS 2911 Part 1 Sec 3 — precast concrete piles (driven precast).
• IS 2911 Part 1 Sec 4 — bored precast piles.
• IS 2911 Part 2 — timber piles.
• IS 2911 Part 3 — under-reamed piles (cast-in-situ with bulb at toe; expansive soil specific).
• IS 2911 Part 4:1985 — load test on piles.
• IS 456:2000 — RCC code (pile concrete + reinforcement).
• IS 1786:2008 — high-strength deformed reinforcement.
• IS 8112:1989 / IS 12269:2013 — cement.
• IS 10262:2019 — mix design.
• IS 9103:1999 — admixtures.
• IS 2131:1981 — SPT (capacity input).
• IS 2720 Part 4 — soil grain-size analysis.
• IS 2720 Part 10:1991 — UCS.
• IS 6403:1981 — bearing capacity.
• IS 1080:1985 — design of shallow foundations.
• IS 1893 Part 1:2016 — earthquake design.
• IS 1888:1982 — plate load test.

1. Driving in urban site without vibration assessment. Adjacent buildings damaged; civil disputes. Pre-construction vibration survey + monitoring during driving. 2. Driving in soft sensitive clay. Soil disturbance reduces shaft friction; pile capacity drops. Use bored (IS 2911 Part 1 Sec 2:2010) instead. 3. Hammer mismatched to pile size. Too light: doesn't drive to refusal; too heavy: damages pile head. Match hammer to pile. 4. Casing extraction too fast. Concrete may not fill voids; pile defects. Slow extraction with vibration. 5. No driving log maintained. Cannot verify capacity post-installation; quality dispute. Mandatory log per pile. 6. Concrete pour into casing without proper level. Voids form; concrete contamination. Maintain pour from one end; verify level. 7. No integrity test after driving. Defects undetected; risk of failure. PIT (low-strain integrity test) cheap insurance. 8. Load test programme inadequate. Initial test on sacrificial pile + routine on 0.5-2 % production. Skipping = no verification. 9. Vibration damage to fresh concrete in casing. Driving energy may damage pile concrete during installation. Allow concrete to set before continuing adjacent piles. 10. Adjacent piles installed too close. Soil disturbance from one pile affects adjacent; capacity reduction. Spacing per design (typically 3-4 × diameter centre-to-centre). 11. Pile group capacity ignored. Group settles more than single pile; group capacity < n × single. Apply group reduction. 12. No pile cap design tolerance for off-position piles. Driven piles often deviate ±150 mm from design position; pile cap reinforcement must accommodate.

Pile foundation project cascade:

1. Geotechnical investigation — boreholes, SPT, soil profile, water table. 2. Pile type selection: - Driven cast-in-situ (this code) — granular soils, non-urban - Bored cast-in-situ (Sec 2) — urban, soft soils - Driven precast (Sec 3) — short piles, factory-controlled - Under-reamed (Part 3) — expansive soils, low-cost residential 3. Pile design: - Capacity per soil profile (skin friction + end bearing) - Diameter + length - Reinforcement - Group design + pile cap 4. Initial load test (IS 2911 Part 4:1985) — sacrificial test pile to ≥ 2.5 × design load. 5. Production piling: - Per design specifications - Driving log + concrete cubes per pile - Sequencing to minimise group disturbance 6. Routine load tests on 0.5-2 % production piles to 1.5 × design load. 7. Integrity tests (PIT) on all piles. 8. Pile cap construction after acceptance.

Driven cast-in-situ is one of the foundational deep-foundation technologies in India. Modern urban construction has shifted toward bored piles for vibration sensitivity; driven piles remain economic + effective for non-urban / brownfield projects.