Internal Erosion Testing & Laboratory Assessment

Internal Erosion Assessments

Internal erosion is an important potential failure mode for embankment dams. Assessing it requires more than reviewing individual soil gradations or applying filter criteria in isolation. The materials need to be understood in the context of the dam's zoning, construction history, and available performance data.

Stratem provides engineering assessments focused on identifying potential internal erosion vulnerabilities and determining where further analysis or laboratory testing may be useful.

Understanding the Embankment

An assessment starts with understanding how the dam was built and how its materials are distributed. Available design drawings, construction records, investigation data, and historical reports can be reviewed to develop an understanding of the embankment and foundation conditions relevant to internal erosion.

Where sufficient gradation data are available, the data can be compiled and assessed spatially to understand material variability and how representative base, filter, transition, and foundation materials relate to the dam's zoning.

Internal Stability and Filter Compatibility

Material gradations can be evaluated for potential internal instability and compatibility between adjacent zones using established internal stability methods and applicable filter criteria.

The objective is not simply to classify individual gradations, but to understand where potentially susceptible materials may occur within the dam and how they relate to surrounding materials and zoning.

Where internal stability remains uncertain, laboratory internal stability testing can provide additional evidence of a material's response to seepage and hydraulic loading.

Evaluating Filter Performance

Base-filter relationships can be assessed using available gradation data and established filter criteria. Where the expected performance of a particular base-filter combination remains uncertain, Continuing Erosion Filter (CEF) testing can provide direct laboratory evidence of its erosion behaviour.

Laboratory testing can be used to address specific uncertainties identified through the assessment rather than as a substitute for understanding the dam and its materials.

Assessment Approach

The scope of an internal erosion assessment depends on the available information and the questions being investigated. Stratem can review available material data, dam zoning, and relevant project records to evaluate potential internal erosion vulnerabilities and identify areas where additional analysis or laboratory testing may be useful.

The assessment can be tailored to the needs of the project, from a focused evaluation of specific materials or base-filter relationships to a broader review of internal erosion considerations.