The foundation of the weir and the creep length according to Bligh's creep theory

The foundation of a weir plays a crucial role in its stability and performance. It is essential to understand the dimensions and characteristics of the foundation to predict its behavior over time. In this case, we are given a weir foundation with specific dimensions, including a horizontal floor, an upstream pile, and a downstream pile.

Foundation Dimensions:

- Horizontal floor length: 30 m
- Upstream pile depth: 8 m
- Downstream pile depth: 12 m

Bligh's Creep Theory:

Bligh's creep theory is a widely accepted concept used to estimate the creep length in cohesive soil foundations. Creep refers to the gradual deformation or settlement of soil under long-term sustained load. It is a time-dependent phenomenon that occurs due to the rearrangement of soil particles and the consolidation of soil layers.

According to Bligh's creep theory, the creep length (Lc) can be determined using the following formula:

Lc = 0.7 * H

Where:
Lc = Creep length
H = Total depth of the foundation

Calculating the creep length:

In this case, the total depth of the foundation (H) can be calculated by summing the upstream pile depth (8 m) with the downstream pile depth (12 m):

H = 8 m + 12 m
H = 20 m

Using the formula mentioned earlier, we can calculate the creep length (Lc):

Lc = 0.7 * 20 m
Lc = 14 m

Therefore, the creep length according to Bligh's creep theory for the given foundation is 14 meters.

Conclusion:

The foundation of the weir consists of a horizontal floor with an upstream pile and a downstream pile. The creep length, according to Bligh's creep theory, is calculated by multiplying the total depth of the foundation by a factor of 0.7. In this case, with a total depth of 20 meters, the creep length is determined to be 14 meters. Understanding the creep behavior of the foundation is essential for predicting long-term settlement and ensuring the stability of the weir structure.