PONDASI PANCANG : part2c_Contoh Hitungan Daya Dukung Berdasar Uji N-SPT - Hinawan T. Santoso, ST, MT

Introduction

This tutorial provides a comprehensive guide on calculating the load-bearing capacity of pile foundations based on N-SPT tests, as discussed in the video "PONDASI PANCANG: part2c_Contoh Hitungan Daya Dukung Berdasar Uji N-SPT" by masdosen. Understanding this process is crucial for engineers and construction professionals involved in foundation design, ensuring safety and structural integrity in construction projects.

Step 1: Understand the N-SPT Test

• Definition: The Standard Penetration Test (N-SPT) is a field test used to determine the geotechnical properties of soil.
• Purpose: It provides insights into soil density and strength, which are vital for calculating the load-bearing capacity of foundations.
• Procedure:
  • Drive a split barrel sampler into the soil at the desired depth.
  • Count the number of blows required to penetrate a set distance (usually 300 mm).
  • Record the blows as the "N value," which indicates soil resistance.

Step 2: Collect and Analyze N-SPT Data

• Data Collection: Perform the N-SPT at various depths to gather a profile of soil conditions.
• Data Analysis:
  • Plot the N values against depth to visualize soil behavior.
  • Identify layers of soil with varying N values to assess their strength characteristics.

Step 3: Calculate Load-Bearing Capacity

• Formula: The load-bearing capacity (Q) of a pile can be estimated using empirical correlations based on the N value.
• Common Formula: [ Q = N \times K ] where K is a factor that depends on the type of pile and soil conditions.
• Practical Example:
  • If N = 20 and K = 10 kN, then: [ Q = 20 \times 10 = 200 , kN ]

Step 4: Consider Additional Factors

• Soil Type: Adjust calculations based on the specific type of soil (clay, sand, silt).
• Pile Type: Different pile types (concrete, steel) may require different K values.
• Safety Factors: Always apply safety factors to account for uncertainties in soil behavior and loading conditions.

Step 5: Validate with Field and Laboratory Tests

• Field Tests: Conduct additional tests such as static load tests to validate the estimated load-bearing capacity.
• Laboratory Tests: Perform soil sample analysis to further confirm geotechnical properties.

Conclusion

Understanding the calculation of load-bearing capacity based on N-SPT tests is essential for effective foundation design. By following the outlined steps, professionals can ensure that their foundations are safe and reliable. Next steps may include exploring more advanced techniques for foundation analysis or diving into specific case studies for practical application.