1. Global check (VTV-2006) - Liquefaction
The global check for liquefaction as implemented in D-Flow Slide is shown in Figure 1 below. It is based is based on the assessment schema described in VTV-2006.
Figure 1: Assessment schema for liquefaction (current schema in D-Flow Slide)
For the coming VTV (2013), a new schema has been proposed, see Figure 2 below.
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2011.
Step 1 : Would liquefaction lead to damage on levee?
The damaging criterion liquefaction (geometrical check) is met if at the so-called assessment level is situated within the slope (i.e. on landward side of) the so-called observation profile, in accordance with Annex 9.4 of the VTV-2006.
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The damaging criterium is not met if the liquefaction point SZV is situated landwards of the observation point Ssign.
where Ssign is the intersection point between the observation profile (from the foreshore) and the assessment level and
SZV is the intersection point between the existing profile and the assessment level.
Step 2: Artificially underwater installed and non-compacted sandy foreshore? (answer is always NO)
By lack of information, D-FLOW SLIDE assumes that no artificially underwater installed and non-compacted sandy foreshore is present (step 2 of the Global check).
Step 3: Criterion on slope protection met?
Directly in front of the toe of the dike or on the outside of the toedumping or to the outward end of a dumping, the slope 1:2.5 may not be cut by the profile. This is not checked because the answer has no influence.
Step 4: Liquefaction possible based on geometry only?
The occurrence of a liquefaction is possible if one of the two following conditions is met:
- The average slope is steeper than or equal to 1:4, over a height of at least 5 m;
- The total slope (channel edge-channel bottom) is on average steeper than or equal to 1:7.