Addressing Excessive Building Settlement: Practical Solutions

When faced with a situation where the estimated settlement of a building surpasses acceptable limits, designers have several avenues to explore in order to manage excessive settlement effectively. Each alternative comes with its own considerations, including construction costs, long-term operation and maintenance costs, and the construction timeline.

1. Alteration of the Structure

1.1 Reorientation or Movement:

Buildings can be reoriented or moved based on site, location, and function.
Feasible in low-value land rural areas.

1.2 Load Redistribution:

Changing framing systems for improved load distribution.
Reducing the number of stories to decrease overall load.

1.3 Load Reduction:

Adjusting operations to relocate the heaviest part of the building to the strongest soil.

1.4 Jacks for Differential Settlement:

Implementation in Mexico City for periodic adjustments in high-rise structures.
Jacks under primary columns for precise adjustments.

2. Alteration of the Foundation

2.1 Deep Foundation:

Commonly adopted to tackle excessive settlement.
Various types based on soil type, material, equipment, and skill availability.

2.2 Floating Foundation:

Excellent for reducing net load on soil and differential settlement.
Consider large raft foundation for expansive areas.

2.3 Combined Footing:

An option to reduce differential settlement.

2.4 Elevation and Contact Pressure Variation:

Adjusting initial elevation or varying contact pressure beneath the foundation.

3. Alteration of Soil Properties

3.1 Soil Improvement Methods:

Grouting, consolidation, dynamic compaction, replacement, lime and cement columns, electroosmosis, freezing, blasting, vibro-replacement, and more.

3.2 Selection Criteria:

Consider operation criteria, soil type, depth, area, volume, material and equipment availability, environmental factors, cost, time, and local experience.

Conclusion

In conclusion, the response to excessive building settlement involves a thoughtful consideration of various options, each with its unique advantages and challenges. Designers must weigh the practicality, cost, and long-term implications of each alternative to ensure a well-informed decision.