Design and construction of bored cast-in-situ piles founded on rocks - Guidelines

IS 14593 Scope Summary:

• IS 14593 deals with design and construction aspects related to foundations on rock and soil.
• It references key IS codes for detailed guidance:
  • IS 12070 (1987): Design & construction of shallow foundations on rocks.
  • IS 13063 (1991): Structural safety of buildings on shallow rock foundations.
  • IS 456 (1978): Plain & reinforced concrete design.
  • IS 1892 (1979): Subsurface investigation for foundations.
  • IS 2131 (1981): Standard penetration test for soils.
  • IS 2911: Pile foundation design and load testing.
  • IS 8009: Settlement calculation for shallow & deep foundations.
  • IS 2809 & IS 11358: Glossaries for soil and rock mechanics terms.

Key Design Considerations (per Clause 6.2):

• Follow factors and procedures outlined in IS 12070 for foundation design on rock.

Important Formula Reference (from IS 12070 & IS 456):

• Bearing Capacity of Rock (approximate):

  [ q_{allow} = \frac{q_u}{FS} ]

  where,
  ( q_u ) = Ultimate bearing capacity of rock (depends on rock type, discontinuities)
  ( FS ) = Factor of safety (typically 3 to 5)

• Settlement Calculation (from IS 8009):

  [ S = \frac{q \times H}{E_s} ]

  where,
  ( S ) = Settlement
  ( q ) = Applied stress
  ( H ) = Thickness of compressible layer
  ( E_s ) = Modulus of elasticity of soil/rock

Summary Table of Relevant IS Codes

IS 14593 References Summary

IS 14593 incorporates key Indian Standards essential for foundation design and soil/rock engineering:

Usage:

• These references provide design principles, test methods, terminology, and safety guidelines.
• Always use the latest edition for compliance and best practice.
• They cover soil testing, pile design, settlement calculation, and rock foundation design.

flowchart LR
    A[IS 14593] --> B[Soil Engineering]
    A --> C[Foundation Design]
    A --> D[Rock Mechanics]

    B --> IS2809[IS 2809: Soil Terms]
    B --> IS2131[IS 2131: SPT Test]
    C --> IS456[IS 456: Concrete]
    C --> IS2911[IS 2911: Pile Foundations]
    C --> IS8009[IS 8009: Settlement]
    D --> IS11358[IS 11358: Rock Terms]
    D --> IS12070

IS 14593 Definitions Summary:

• The standard adopts definitions from IS 2809 (soil engineering) and IS 11358 (rock mechanics) for terms and symbols.
• It references related IS codes for foundational concepts and practices in soil and rock engineering.
• Key related IS codes include:

No explicit formulas or tables are provided in IS 14593 for definitions; instead, it directs users to the above standards for detailed terminology.

Recommended Action:

• Refer to IS 2809 and IS 11358 for comprehensive terminology.
• Use IS codes like IS 1892 (subsurface investigation) and IS 2911 (pile foundations) for design parameters and formulas related to soil and rock foundation engineering.

graph LR
A[IS 14593 Definitions] --> B[IS 2809: Soil Engineering Terms]
A --> C[IS 11358: Rock Mechanics Terms]
A --> D[Related IS Codes for Design & Construction]
D --> E[IS 12070: Shallow Rock Foundations]
D --> F[IS 13063: Structural Safety on Rock]

This ensures consistent use of terms across soil and rock foundation design and construction.

IS 14593: Information Required for Design and Construction of Bored Cast-in-Situ Piles in Rock

Key Information Required (Clause 4.1)

• Geotechnical Data:

  • As per IS 2911 (Part 1/Sec 2) and IS 1892, IS 13063.
  • Rock profile, geological data, and engineering/physical properties of rock strata (IS 13063).
  • Rock below pile tip level (minimum 5 m into bedrock).

• Environmental Data:

  • Flood levels, scour depths, normal water levels for bridges.
  • Marine construction data per IS 4651 (Part 4).

• Chemical Tests:

  • Chlorides, sulphates, alkali, and other deleterious chemicals in soil/rock and groundwater.

Relevant IS Codes for Reference

Design Considerations (per IS 12070 referenced in 6.2)

• Subsoil strata characteristics
• Groundwater conditions
• Rock type and embedment depth
• Chemical aggressiveness

Summary Table: Essential Data for Design

This structured data ensures safe, durable pile foundation design and construction in rock conditions.

IS 14593 - Equipment and Accessories: Key Points

• Design Factors (Clause 6.2): Follow IS 12070 for design parameters like load factors, safety margins, and material properties.

• Load Carrying Capacity (Clause 6.5):
  Calculate using:
  [ P_{u} = A_s f_y + A_c f_{cd} ]
  where:

  • (P_u) = ultimate load capacity
  • (A_s) = area of steel reinforcement
  • (f_y) = yield strength of steel
  • (A_c) = area of concrete
  • (f_{cd}) = design compressive strength of concrete

• Design Considerations (Clause 6.7.3):

  • Ensure compatibility with soil conditions (refer IS 12070)
  • Account for dynamic and static loads
  • Factor in corrosion protection and durability

• Glossary: Terms related to soil engineering (bearing capacity, settlement, etc.) are defined for clarity.

Summary Table: Load Carrying Capacity Parameters

flowchart TD
    A[Design Factors (IS 12070)] --> B[Load Carrying Capacity Calculation]
    B --> C[Steel Area \(A_s\), Yield Strength \(f_y\)]
    B --> D[Concrete Area \(A_c\), Design Strength \(f_{cd}\)]
    C & D --> E[Ultimate Load Capacity \(P_u\)]
    E --> F[Design Considerations (Durability, Soil Compatibility)]

For detailed design, always refer to IS 12070 alongside IS 14593.

IS 14593: Design Considerations for Rock Socketed Piles

Key Points from Clause 6.7.3 & 6.5.1

• Design factors per IS 12070 must be considered (soil/rock properties, loading, geometry).
• Compression capacity depends on:
  • Uniaxial compressive strength of rock
  • Limit pressure of rock
  • Shear strength of rock
  • Structural strength of pile
• Minimum socket length should be estimated by static computations and preferably verified by load tests.

Table 1: Suggested Minimum Length of Socket (L_socket)

• D = diameter of the pile

Design Formulae (General Concept)

• Compression capacity, Q = Side shear capacity + End bearing capacity
• Side shear capacity depends on rock shear strength and socket surface area.
• End bearing capacity depends on rock compressive strength and base area.

flowchart TD
    A[Design Considerations] --> B[Rock Properties]
    A --> C[Geometry of Socket]
    A --> D[Load Types]
    B --> E[Uniaxial Compressive Strength]
    B --> F[Shear Strength]
    C --> G[Diameter (D)]
    C --> H[Socket Length (L_socket)]
    D --> I[Compression Load]
    I --> J[Side Shear]
    I --> K[End Bearing]

Summary: Use Table 1 for minimum socket length based on rock type, evaluate load capacity by combining side shear and end bearing, and verify design with load tests as per IS 14593 and IS 12070 guidelines.

IS 14593 references several codes related to materials and stresses but does not provide direct formulas or tables within itself. Key related standards are:

• IS 456:1978 — Plain and reinforced concrete design (for stresses in concrete and steel)
• IS 12070:1987 — Design on shallow foundations on rock (material properties of rock)
• IS 13063:1991 — Structural safety of buildings on shallow rock foundations

Key Concepts for Materials and Stresses:

• Concrete stresses (IS 456):
  • Permissible compressive stress in concrete, ( f_{cd} = \frac{f_{ck}}{\gamma_c} )
  • Permissible tensile stress in steel, ( f_{yd} = \frac{f_y}{\gamma_s} )
• Factor of Safety (FoS) (Clause 6.12):
  • Typically ranges from 2 to 3 for foundation design depending on soil/rock conditions.
• Rock properties (IS 12070):
  • Uniaxial compressive strength, modulus of elasticity, and Poisson’s ratio are key parameters.

Typical Material Properties Table (Indicative):

Summary Formula for Bearing Capacity on Rock:

[ q_{allow} = \frac{q_{u}}{FS} ] Where:

• ( q_u ) = Ultimate bearing capacity of rock
• ( FS ) = Factor of Safety (usually ≥ 3)

flowchart TD
    A[Material Properties] --> B[Concrete (IS 456)]
    A --> C[Steel (IS 456)]
    A --> D[Rock (IS 12070)]
    B --> E[Permissible stresses]
    C --> E
    D --> F[Rock strength parameters]
    F --> G[Foundation design]
   

Key Construction Practices per IS 14593 (Referencing IS 2911 Part 1/Sec 2)

• Materials: Cement, steel, and concrete must comply with IS 2911 (Part 1/Sec 2) standards.
• Workmanship: Follow IS 2911 (Part 1/Sec 2) for piling installation, concrete placing, and quality control.
• Piling Installation:
  • Control methods and installation procedures as per IS 2911.
  • Ensure cleaning of pile bore and socket before concreting.
  • Concreting must be immediate and uninterrupted after cleaning.
• Reinforcement: Use reinforcement provisions as per IS 2911 (Part 1/Sec 2), Clause 6.15.
• Recording: Maintain detailed piling data records including defects and remedies.

Relevant References for Deeper Details:

Summary Diagram of Construction Practice Flow

flowchart TD
    A[Site Preparation] --> B[Subsurface Investigation (IS 1892)]
    B --> C[Pile Bore Cleaning]
    C --> D[Reinforcement Placement (IS 2911)]
    D --> E[Concreting (Immediate & Uninterrupted)]
    E --> F[Quality Control & Recording]

This ensures compliance with IS 14593 by adhering to referenced IS codes for materials, workmanship, and construction sequence.

IS 14593: Load Testing and Performance Evaluation of Piles

Key Clauses:

• Clause 9.2: Vertical Load Test

  • Specifies procedures for applying and measuring vertical loads on piles.
  • Load increments typically up to 2-3 times the design load.
  • Monitor settlement at each load step until failure or maximum load.

• Clause 6.5: Estimation of Load Carrying Capacity

  • Combines soil parameters and pile geometry.
  • Uses ultimate bearing capacity formulas based on soil type and pile embedment.

Typical Load Test Procedure (per IS 2911 Part 4 referenced):

• Apply load in increments (e.g., 25%, 50%, 75%, 100% of test load).
• Hold each load for a specified time (e.g., 1 hour) to measure settlement.
• Load is increased until failure or maximum test load.
• Allow unloading and observe rebound settlement.

Basic Formula for Ultimate Load Capacity (Approximate):

[ Q_u = Q_s + Q_b ]

Where:

• (Q_u) = Ultimate pile load capacity
• (Q_s) = Shaft resistance (skin friction)
• (Q_b) = Base resistance (end bearing)

Reference Tables (from IS 2911 Part 1 & 4):

Summary:

• Perform vertical load tests as per Clause 9.2.
• Estimate load capacity combining shaft and base resistances (Clause 6.5).
• Refer IS 2911 (Part 4) for detailed load test methodology.
• Use referenced IS codes (e.g., IS 456, IS 1892) for supporting design and soil investigation.

flowchart TD
    A[Start Load Test] --> B[Apply Load Increment]
    B --> C[Measure Settlement]
    C --> D{Settlement Acceptable?}
    D -- Yes --> E[Increase Load]
    D -- No --> F[Stop Test]
    E --> B
    F

IS 14593: Safety Factors Summary

• Minimum Factor of Safety (FoS):

  • As per Clause 6.12.1, the minimum FoS on static formula = 6.
  • This is a baseline; actual FoS depends on load-settlement behavior of the entire structure at the site.

• Conditions for Increasing FoS:

  • Clause 6.12.2 states FoS should be increased if:
    • Rock conditions are unfavorable.
    • There is deterioration over time.
    • Vibrations from structure or equipment exist.

• Transient Loading:

  • Refer to IS 2911 (Part 1/Sec 2) for transient load considerations (Clause 6.13).

• Additional Design Factors:

  • See IS 12070 for other design factors influencing safety.

Key Formula (Static Load Safety Factor)

[ \text{FoS} = \frac{\text{Ultimate Load Capacity}}{\text{Allowable Load}} ]

• Minimum FoS = 6 (static conditions).

Visual Summary

flowchart TD
    A[Design Safety Factor] --> B{Conditions}
    B -->|Normal| C[FoS ≥ 6]
    B -->|Unfavorable Rock| D[Increase FoS]
    B -->|Deterioration| D
    B -->|Vibrations| D
    D --> E[Higher FoS as per site conditions]

References:

• IS 14593 Clause 6.12, 6.13
• IS 2911 (Part 1/Sec 2) for transient loading
• IS 12070 for design factors

IS 14593 refers reinforcement provisions mainly to IS 2911 (Part 1/Sec 2), which governs materials, stresses, and workmanship for reinforced concrete piles.

Key Points on Reinforcement (from IS 2911 Part 1/Sec 2):

• Reinforcement Materials: Use of high-yield strength deformed bars or mild steel bars conforming to IS 1786.
• Minimum Reinforcement: Typically, minimum steel area is about 0.8% to 1.2% of the cross-sectional area for concrete piles.
• Stress Limits:
  • Steel stress in tension, ( f_{st} ) ≤ 0.87 ( f_y ) (where ( f_y ) = characteristic yield strength of steel)
  • Concrete stress limits as per IS 456.
• Development Length: As per IS 456, development length ( l_d ) depends on bar diameter, concrete grade, and cover.
• Cover to Reinforcement: Minimum cover for piles is usually 40 mm to protect against corrosion and ensure bond.
• Reinforcement Detailing:
  • Longitudinal bars spaced uniformly around the pile cross-section.
  • Stirrups or ties provided at spacing ≤ 300 mm to prevent buckling.

Typical Reinforcement Formulae:

[ A_s = \rho \times A_c ]

• ( A_s ) = Area of steel
• ( \rho ) = Reinforcement ratio (0.008 to 0.012)
• ( A_c ) = Cross-sectional area of concrete pile

Summary Table for Reinforcement in Concrete Piles

flowchart TD
    A[Concrete Pile] --> B[Longitudinal Reinforcement]
    A --> C[Stirrups / Ties]
    B --> D[Minimum 0.8

IS 14593: Reporting and Documentation - Key Points

IS 14593 does not provide explicit formulas or tables specifically for reporting and documentation but refers to related standards and general rules:

Key Specifications:

• Rounding Off:
  Final test or analysis values must be rounded as per IS 2:1960 ("Rules for rounding off numerical values").

• Referenced Codes for Reporting Context:

  • IS 456:1978 – Plain and reinforced concrete practice
  • IS 1892:1979 – Subsurface investigation for foundation
  • IS 2131:1981 – Standard penetration test for soils
  • IS 2911 (Parts 1-4) – Pile foundation design and load tests
  • IS 8009 (Parts 1 & 2) – Settlement calculation for shallow and deep foundations
  • IS 12070:1987 & IS 13063:1991 – Foundations on rock

Recommended Reporting Elements:

• Test description and location
• Methodology and standards followed
• Raw and processed data with units
• Final results rounded per IS 2:1960
• Interpretation and conclusions referencing appropriate IS codes

Example: Rounding Off (IS 2:1960)

flowchart TD
  A[Test/Analysis] --> B[Data Collection]
  B --> C[Data Processing]
  C --> D[Rounding off (IS 2:1960)]
  D --> E[Documentation]
  E --> F[Final Report referencing IS codes]

For detailed reporting formats, consult the referenced IS codes relevant to your test or foundation type.

IS 14593 does not provide direct formulas or tables under the "Technical Committee" heading. Instead, it references:

• Technical Committee: Rock Mechanics Sectional Committee, CED 48 (Annex A)
• Related IS Codes:
  • IS 12070:1987 — Design and construction of shallow foundations on rocks
  • IS 13063:1991 — Structural safety of buildings on shallow rock foundations
• Glossary: Terms and symbols related to rock mechanics and soil engineering are included for clarity.

For detailed formulas or tables, refer to IS 12070 and IS 13063, which cover foundation design on rock, including bearing capacity, allowable settlement, and safety factors.

Example: Bearing Capacity on Rock (from IS 12070)

[ q_{all} = \frac{q_u}{FS} ]

• ( q_u ) = Ultimate bearing capacity of rock
• ( FS ) = Factor of safety (typically 3 to 5)

For more precise design parameters, consult the specific IS codes mentioned.

IS 14593 Glossary of Terms and Symbols: Key Points

• Scope:
  Defines terms and symbols for soil and rock engineering, referencing IS 2809 (soil) and IS 11358 (rock mechanics).

• Referenced IS Codes for Terminology:

  IS No.	Title
  2809	Glossary of terms and symbols relating to soil engineering
  11358	Glossary of terms and symbols relating to rock mechanics

• Common Symbols and Terms (from IS 2809 & IS 11358):

• Additional References for Design and Testing:
  • IS 1892: Subsurface investigation
  • IS 2131: Standard Penetration Test
  • IS 456: Concrete design
  • IS 2911: Pile foundations
  • IS 12070, IS 13063: Foundations on rock

Summary Diagram of Symbol Relations

graph LR
  Stress(σ) --> ShearStress(τ)
  SoilProperties -->|includes| Cohesion(c)
  SoilProperties -->|includes| FrictionAngle(φ)
  SoilProperties -->|includes| UnitWeight(γ)
  SoilProperties -->|affects| Stress(σ)
  Stress(σ) -->|related to| ModulusElasticity(E)

Use IS 2809 and IS 11358 for detailed definitions and symbols when working with IS 14593.