This article explains how the 1200 base block can increase the capacity of a block materials storage bunker.
The 1200 Interbloc base block is a type of block that can be used to build higher capacity storage bins. The base block spreads the load from the wall and surcharge over a greater area of the underlying foundation, which reduces the foundation requirement and increases the load the wall can take.
Benefits of using base blocks:
- Increased capacity: The base block allows for higher walls to be built, which can increase the storage capacity of the bin.
- Reduced foundation requirements: The base block spreads the load over a larger area, which can reduce the size and depth of the foundation required.
- Easy to install: The base block can be installed in the same way as a standard Interbloc block, with the same vertical reinforcing requirements.
- Keeps the bin cleaner: The base block prevents aggregation of material in corners and other areas, which can help to keep the bin cleaner.
Indicative analysis of how the base block increases the capacity of a wall:
Aggregate Storage:
|
Standard Wall |
Base Block Wall |
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Backfill |
Unit weight of 18kN/m³ (roughly 1800kg/m3). Angle of internal friction is 30°. Angle of friction between structure and soil is 20°. Cohesion of soil is 0kPa. Permanent long term (effective stress). No slope behind the wall. |
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Overturning moment |
11.59kNm/m |
12.30kN/m |
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Resisting moment |
13.10kNm/m |
34.88kNm/m |
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Safety factor in overturning stability |
1.13 FAIL |
2.84 PASS |
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Unfactored pressure on substrate* |
>300kPa |
54.36kPa |
Fertiliser Storage
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Standard Wall |
Base Block Wall |
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Backfill |
Unit weight of 12kN/m³ (roughly 1200kg/m). Angle of internal friction is 35°. Angle of friction between structure and material is 22°. Cohesion of material is 0kPa. Permanent long term (effective stress). Slope behind wall is 35°. |
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Overturning moment |
18.55kNm/m |
18.51kN/m |
|
Resisting moment |
15.56kNm/m |
39.08kNm/m |
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Safety factor in overturning stability |
0.84<1.50 UNSTABLE |
2.11>1.50 PASS |
|
Unfactored pressure on substrate* |
>300kPa |
70.53kPa |
How the base block distributes the load:
The base block is geometrically concentric, which means that the self-weight of the wall is distributed evenly across the increased width of the base block. This results in a more stable wall that is less likely to overturn.
How the base block reduces foundation requirements:
The base block spreads the load over a larger area, which reduces the pressure that is exerted onto the substrate. This can reduce the size and depth of the foundation required, which can save time and money.
Can the blocks be used on compacted metal surfaces?
Yes, the base blocks can be used on compacted metal surfaces, provided that the following conditions are met:
- The wall is under 1.8 meters high.
- The wall utilizes "top and bottom" fixing kits to tie the wall together.
- The material stored does not exceed the loading and material characteristics in the examples given.
- Foundation preparation will be extra critical as the wall will be highly susceptible to undulation in the ground.
- Sites in the Upper North island where earthquake hazard risk is comparatively lower.
Technical considerations on when to use 1200 base blocks:
Base blocks should be used for industrial or commercial bulk storage applications, specifically in the following industries:
- Refuse and recycling
- Fertilizer and grain
- Aggregate storage and quarries
- Civil contractors
Base blocks should also be used for retention walls (excluding for settlement ponds) and for walls 1.8 meters high and above with loading scenarios that match the examples given.
Base blocks should be specified for use in all structures, especially when:
- The customer has opted not to proceed with an engineered design.
- The bearing capacity of the ground is sub-optimal or unknown.
- The thickness of the concrete foundation is uncertain.