January 8th, 2021

Flood protection Willows - dye ingestion by means of sheet wall inner gasket

Dike crown path equals dike defense path, planned sheet wall course on water-side dike top edge

Dike crown path equals dike defense path, planned sheet wall course on water-side dike top edge

The flood protection Weiden was manufactured in several construction phases from 1995 according to a rule profile approved by the Bavarian State Office for the Environment. Existing trees and plantings were then approved in the design and integrated into the new dikes. The dikes were statically inspected in 2019 in accordance with the current requirements of the Bavarian State Office for the Environment.

Significant deficiencies in the deer level safety were found for the windfall, due to the eruption of the root plate after falling trees, which can reduce more than half of the dike cross-section.

In October 2020, Tractebel Hydroprojekt GmbH was commissioned with the object planning for the execution of the installation of a sheet wall as a statically effective internal seal with the performance phases 1 to 3, optional lynot to 9, including a natural assessment by the Weiden Water Management Office. After a thorough review of the existing documents, it was necessary to extend the scope of the contract to the structural planning performance phase 1 to 4, optionally to 6.

The dike section is located on the orographically right side of the flood channel of the Waldnaab and protects the inner city area of Weiden in the Upper Palatinate up to a hundred-year flood event. Since the area is used as a recreation area, the promoter decided to refrain from completely clearing the trees and instead retrofit an inner seal by means of a sheet wall in the dike in order to ensure the deer stand safety in the event of a wind fall. When determining the pile wall axis in the approximately 700 m long planning section, particular emphasis should be placed on minimising the impairment of the existing vegetation, partly with capital oaks, pointed maple, ash, etc., which can be found at all altitudes on the water-side embankment. Furthermore, the dye defense, which takes place on half the project length only via the dike crown path, is to be maintained in case of damage. The sheet wall is therefore arranged in areas with existing dike back path in dike axis and in the remaining sections at the water-side dike top edge. Approval and execution is planned for 2021.

Thomas Zacharias, Bernhard Ebner - Munich

Failure mechanism and static system for the design of the internal seal for the design situation "loss of embankment due to tree throwing"

Failure mechanism and static system for the design of the internal seal for the design situation "loss of embankment due to tree throwing"