Guide for lateral dynamic load test on piles

IS 9716: Scope Summary & Key Specifications

Scope (Clause 3.1):
For conducting pile load tests, the following data is essential:

• Pile Details:

  • Type (material, reinforcement)
  • Installation method (driving/casting)
  • Depth, cut-off level, cross-section details

• Pile Location:

  • Position in group (test/working pile)
  • Condition under cap/scour

• Soil & Water Table:

  • Subsoil strata profile
  • Water table position

• Load Capacities:

  • Allowable & ultimate vertical load
  • Actual design loads (vertical, lateral, moments)

• Structure & Loading:

  • Type of structure supported
  • Nature of loading (including seismic)

• Additional Info:

  • Past test experience
  • Any other relevant test planning data

Key Formula (from Clause 6.3 for Forced Vibration Test):

[ K = \text{Pick-up calibrated length (mm)} ]

Where:

• ( S = ) Paper speed in oscillograph (mm/sec)
• ( m = ) Eccentric mass of oscillator (kg·sec³/mm)
• Acceleration for 2g = ( 2 \times 9810 , \text{mm/sec}^2 )

Appendix A:
Contains suggested tabular format for recording test quantities (Clause 6.1 to 6.3).

Summary Diagram of Scope Inputs

graph TD
  A[Pile Load Test Scope] --> B[Pile Details]
  A --> C[Location & Condition]
  A --> D[Soil & Water Table]
  A --> E[Load Capacities]
  A --> F[Structure & Loading]
  A --> G[Additional Info]

This ensures comprehensive planning and execution of pile load tests per IS 9716.

IS 9716: Definitions & Key Parameters

• Soil-Pile Stiffness, ( k_{ap} ):
  Defined as the dynamic force per unit deflection (static amplitude ( x_{st} )) from dynamic load tests:
  [ k_{ap} = \frac{\text{Dynamic Force (F)}}{\text{Static Amplitude (} x_{st} \text{)}} ] Units: kg/cm

• Reference Codes for Definitions:

  • IS 2810-1979 (Soil dynamics glossary)
  • IS 2911 (Parts I-IV) (Pile foundation design & testing)
  • IS 5249-1977 (Dynamic soil properties)

• Parameters from Clause 1.40:

  • ( k_{ap} ): Soil-pile stiffness (kg/cm)
  • ( A_z ): Deflection coefficient for free-headed pile at ground surface
  • ( E ), ( I ): Modulus of elasticity and moment of inertia of the pile (see 6.8.1)

• Appendix A: Suggested tabular format for recording dynamic test quantities (force, deflection, stiffness).

Summary Table for Soil-Pile Stiffness Calculation

flowchart LR
    A[Dynamic Load Test] --> B[Measure Dynamic Force (F)]
    A --> C[Measure Static Amplitude (x_st)]
    B --> D[Calculate Soil-Pile Stiffness k_ap = F/x_st]
    C --> D
    D --> E[Use k_ap for pile design & analysis]

Note: Refer IS 9716 Clauses 2.4, 6.7, 6.8.1 and Appendix A for detailed procedures and data recording formats.

IS 9716 - Information Required for Testing (Forced Vibration Test on Piles)

Key Information Required (Clause 3.1)

• Pile Details: Type, material, reinforcement, installation method (driving/casting).
• Dimensions: Pile depth, cut-off level, cross-section details.
• Location: Piling plan, pile position in group, test or working pile, pile condition (e.g., under cap, scour).
• Soil Data: Sub-soil strata, water table position.
• Load Data: Allowable/ultimate vertical load, design loads (vertical & lateral), static moments.
• Structure Type: Nature of loading (including seismic).
• Additional: Past experience, other relevant test planning info.

Tabular Form for Test Records (Appendix A & Clause 7.1)

Important Formulas

• Frequency:
  [ f = \frac{n}{\text{Length of record (s)}} ]

• Absolute Acceleration:
  [ a = \text{Acceleration on record} \times

IS 9716: Testing Equipment for Lateral Forced Vibration Test on Piles

Key Specifications & Data (from Clauses 3.1, 4.1, 6.1, 7.1)

• Test Equipment: As per IS 5249-1977, equipment includes calibrated acceleration pick-ups, vibration generators, and recording devices.
• Pile Info Required (3.1):
  • Pile type, reinforcement, installation method
  • Pile depth, cross-section, cut-off level
  • Piling plan & location, soil strata & water table
  • Load capacities (allowable/ultimate), design loads
  • Structure type & loading nature (e.g., seismic)
• Test Records (Appendix A & Clause 7.1): Use tabular form with vibration data:

Important Formulae

[ \text{Frequency} (f) = \frac{n \times X_s}{\text{Length of record}} ]

[ \text{Amplitude} (A_z) = \frac{\text{Absolute acceleration}}{4\pi^2 f^2} ]

[ \text{Dynamic force} (F) = m \times e \times 4 \pi^2 f^2 \times A_z ]

Where:

• ( m ) = mass of pile or test assembly
• ( e ) = eccentricity (m)
• ( f ) = frequency (Hz)
• ( A_z ) = amplitude (m)

IS 9716: Key Points on Tests on Piles

1. Essential Information Before Testing (Clause 3.1)

• Pile details: Type, material, reinforcement, installation method (driving/casting).
• Geometry: Pile depth, cut-off level, cross-section.
• Location: Piling plan, position in group, test or working pile, and pile condition (e.g., under cap or exposed).
• Soil: Sub-soil strata, water table level.
• Load: Allowable & ultimate vertical loads; design vertical & lateral loads including moments.
• Structure: Type and nature of loading (e.g., seismic).
• Additional: Past experience and relevant info for test planning.

2. Dynamic Load Test Setup (Clause 4.1.11)

• Use a pulling device (e.g., screw with clutch) to apply and suddenly release horizontal force on the pile for free vibration tests.

3. General Notes on Testing (Clause 2.1)

• Pile response depends on soil, superstructure restraints, sustained load, and ground motion.
• Group behavior is critical since piles function collectively.
• Results should be rounded per IS 2:1960 rounding rules.

Typical Test Parameters & Formulas (from general knowledge):

Summary Diagram: Pile Test Setup

graph LR
A[Pile] --> B[Clamp Attachment]
B --> C[Pulling Screw with Clutch]
C --> D[Horizontal Force Applied & Released]
A --> E[Soil Layers & Water Table]

**Use IS 9716 as a guideline for test planning and execution, complementing with IS 2911 for static load

IS 9716: Analysis of Test Data for Lateral Dynamic Load Tests on Piles

Key Points & Formulas (Clause 7.1 & Appendix A)

Report Contents (Clause 7.1)

• Vibration records and tables
• Plots for:
  • Soil-pile response
  • Natural frequency of soil-pile system
  • Damping coefficient
  • Soil-pile stiffness
  • Soil modulus
• Illustrative figures and observations

Summary Table Example (Appendix A format)

IS 9716: Key Formulas, Tables & Report Specifications for Lateral Forced Vibration Test on Piles

1. Report Content (Clause 7.1)

The test report must include:

• Pile details (type, depth, reinforcement, installation method)
• Subsoil strata and water table info
• Observations: vibration records, tables, plots
• Analysis results:
  • Natural frequency (f) of soil-pile system
  • Damping coefficient
  • Soil-pile stiffness
  • Soil modulus
• Illustrative figures and remarks

2. Suggested Tabular Format (Clause 7.1, Appendix A)

IS 9716: Key Formulas, Tables & Specifications from Appendices

Appendix A: Tabular Form for Forced Vibration Test Records (Clause 6.1)

A suggested record format includes:

Important Formulas:

• Dynamic Force, F:
  [ F = m \times e \times 4 \pi^2 f^2 \times A_z ]
  where:

  • (m) = mass of pile section
  • (e) = eccentricity (mm)
  • (f) = frequency (Hz)
  • (A_z) = amplitude (mm)

• Soil-Pile Stiffness, (k_{ap}):
  [ k_{ap} = \frac{\text{Dynamic Force}}{\text{Static Amplitude}} ]
  (Units: Force per unit deflection, e.g., kN/mm)

Report Requirements (Clause 7.1)

• Include vibration records, plots of soil-pile response
• Calculate and report:
  • Natural frequency of soil-p