Effect of groundwater flow on slope stability

For each slope stability analysis, the groundwater flow regime is to be studied thoroughly since pore water pressures reduces the effective stress and thus the shear strength. Moreover, in case of seepage, the danger exists for erosion and/or piping. Both phenomena can initiate failure of the slope. 

The most critical water levels both inside and outside the soil mass need to be selected with care. In general the (upstream) groundwater in the soil is taken at a high level because this influences seepage while outside water levels at the downstream face are chosen at lowest level for slope stability analysis. Both selected water levels, upstream and downstream, need to be compatible and time effects may have to be taken into account. A typical example is a water reservoir for which 

Water management is typically an issue in case hydraulic fills are deposited above the groundwater table. Verification of the stability of retaining bunds is often a requirement for hydraulic fill works. 

Retaining bunds are generally built using local soil, at least for the first lift of 2 m to 3 m. For the next lifts, the fill material itself is used in a system comparable to 

For the first hft in the construction of containment bunds, frequently local soil is used. Moderate compaction (e.g. by a bulldozer) might be required to prevent the creation of more permeable zones which may soften during subsequent fill lifts. 

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