{"id":8165,"date":"2025-09-06T22:03:01","date_gmt":"2025-09-07T01:03:01","guid":{"rendered":"https:\/\/vinq.us\/?p=8165"},"modified":"2025-11-13T18:18:58","modified_gmt":"2025-11-13T21:18:58","slug":"piping-em-barragens-modelagem-e-geotecnia","status":"publish","type":"post","link":"https:\/\/vinq.us\/en\/piping-em-barragens-modelagem-e-geotecnia\/","title":{"rendered":"Piping in Dams: Between Modeling of Rupture Studies and Geotechnical Mechanisms"},"content":{"rendered":"
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The hypothetical rupture study by <\/span>piping in dams<\/b> aims to conservatively evaluate the possible effects of a failure resulting from this mechanism, even if the probability of its actual occurrence is considered low. For this type of analysis, it is common to use simplifications, such as the adoption of <\/span>parameterized hydrographs<\/b> or the representation of a <\/span>idealized loophole<\/b>, without the internal processes of initiation and evolution of erosion being modeled in detail.<\/span><\/p>

Relationship Between Scenarios and Piping Geotechnics<\/b><\/h2>

When a correlation is established between such scenarios and the geotechnics of piping, it is noted that the initiation and propagation of internal erosion follow well-known mechanisms for different soil types, serving as a basis for giving greater consistency to hypothetical rupture studies.<\/span><\/p>

Initiation of the process<\/b><\/h3>

In geotechnical terms, the start of piping is directly related to the balance between the <\/span>mobilized hydraulic force<\/b>, expressed by the hydraulic gradient, and the <\/span>soil resistance to erosion<\/b>. The <\/span>EUROCODE 7<\/b>, the classical criterion of <\/span>Terzaghi<\/b> for critical gradient and the experiments of <\/span>Hanson & Simon (2001)<\/b> indicate that piping starts when the <\/span>hydraulic shear stress (\u03c4)<\/b> surpasses the <\/span>critical shear stress (\u03c4c)<\/b> of the material.<\/span><\/p>

This behavior varies depending on the type of soil: in <\/span>sands and silts<\/b>, progressive transport of particles occurs; already in <\/span>cohesive soils<\/b>, initiation is slower due to greater resistance, but once triggered, the process evolves rapidly with the transport of fines and increasing hydraulic gradients.<\/span><\/p>

Development of Piping in Dams<\/b><\/h2>

Applied to the context of earth or rockfill dams, piping can be developed in critical zones, such as contacts between the massif and foundation, poorly compacted interfaces, or regions where fine materials are interstitially present.<\/span><\/p>

Once initiated, the concentrated flow removes fine particles and tends to gradually widen the erosion path until it forms continuous trajectories. This mechanism, documented in geotechnical literature, is generally described in three stages:<\/span><\/p>

  1. Initiation<\/b> \u2013 moment when particle displacement begins.<\/span>
    <\/span><\/li>
  2. Progressive erosion<\/b> \u2013 intensification of transport and lengthening of the erosion path.<\/span>
    <\/span><\/li>
  3. Formation of unstable galleries<\/b> \u2013 critical phase that could culminate in structural collapse.<\/span>
    <\/span><\/li><\/ol>

    In hypothetical rupture studies, however, this sequence is rarely represented. Piping progression is assumed to be a final state of a breach formed in shorter timescales than the physical ones, thus ensuring a conservative assessment of downstream impacts. This methodological difference is deliberate: while <\/span>geotechnics<\/b> seeks to understand the mechanisms and estimate the probability of occurrence, the <\/span>Dam Break studies<\/b> focus on the consequences of the rupture, without detailing the internal erosion.<\/span><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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    Figure 5-1 \u2013 Stream nets illustrating the increase in catchment area as erosion length increases. (a) incipient area; (b) after erosion has proceeded for a considerable distance. Source: adapted from dos Santos (2018).<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    Connection Between Geotechnics and Rupture Studies<\/b><\/h2>

    Despite the methodological simplification, the connection between the two fields is clear. Geotechnics provides critical parameters that allow for the calibration of more realistic and defensible scenarios, such as:<\/span><\/p>