Importance of Pore Pressure during Construction of Earthen Dam

Pore pressure is the pressure exerted by the water or other fluids within the voids or pores of a soil mass. During the construction of an earthen dam by hydraulic fill method, pore pressure development becomes important in the central impervious core. The reasons are explained below:

Central Impervious Core

The central impervious core is the most critical part of the earthen dam, which prevents the seepage of water through the dam. It is usually constructed by compacting a suitable clayey material to achieve the required permeability. During the construction, the clayey material is placed in layers and compacted using a suitable compaction method. As the layers are placed, the water is added to provide the required moisture content for compaction. The water fills the voids between the soil particles and exerts a pore pressure.

Importance of Pore Pressure

The development of pore pressure within the impervious core is critical during the construction of the earthen dam. The reasons are:

- Pore pressure affects the stability of the impervious core. The excess pore pressure reduces the effective stress within the core, which may lead to the instability of the core. Therefore, it is necessary to monitor the pore pressure during the construction and take appropriate measures to reduce the excess pore pressure.
- Pore pressure affects the permeability of the impervious core. The excess pore pressure may cause the soil particles to become separated, which may increase the permeability of the core. Therefore, it is necessary to monitor the pore pressure during the construction and take appropriate measures to reduce the excess pore pressure.
- Pore pressure affects the settlement of the impervious core. The excess pore pressure may cause the soil particles to become separated, which may increase the settlement of the core. Therefore, it is necessary to monitor the pore pressure during the construction and take appropriate measures to reduce the excess pore pressure.

Conclusion

In conclusion, during the construction of an earthen dam by hydraulic fill method, the development of pore pressure becomes important in the central impervious core. The excess pore pressure affects the stability, permeability, and settlement of the core. Therefore, it is necessary to monitor the pore pressure during the construction and take appropriate measures to reduce the excess pore pressure.