EP2500472A1 - Partially foamed gravel fixing for dams and dykes - Google Patents

Abstract

Partially or completely foamed ballast composite on freely overflowable dam/dike substructure comprises ballast stones and polyurethane foam, which is placed between the gravel stones. An independent claim is included for solidifying the ballast stones on freely overflowable dam/dike substructure comprising piling ballast stones on the dam/dike substructure and applying a reaction mixture for producing a polyurethane foam between the piled ballast stones.

Description

The invention relates to partially expanded ballast consolidations on overflowable dykes and dams and a method for their production.

Dams, dykes, summer dikes, chafing oaks, flood dikes, backwoods, guide dikes, flood retention basins and overflow basins are referred to in this application as dams and / or dykes for the sake of simplicity.

Flood retention basins are an important part of technical flood protection. Technical flood protection is part of the flood protection strategy. It is supplemented by the flood-area management and flood protection (overflowable dams and embankments, issued by the State Institute for Environmental Protection (LfU) Baden-Württemberg, 1st edition, Karlsruhe 2004 and Design of Small Dams (Water Resources Technical Publication Series), Revised 3 ^rd Edition, United States Department of Interior).

The most important security element of a flood retention basin is the flood relief system. In combination with a sufficient freeboard, the dam is protected from overflow and destruction even in the event of an extreme flood event (see Fig. 1 ).

The flood relief of a partially or completely overflowed dam serves the harmless flood discharge via the dam structure and is lowered compared to the rest of the dam crest.

Overflowable embankment areas are an alternative in terms of landscape aesthetics, hydraulic load capacity and cost considerations with several advantages over conventional flood relief systems. By eliminating the freeboard, the dam height is reduced in completely overflowable dams.

• • Erosion eines Einzelsteins (Ein einzelner Stein wird aus dem Verbund herausgelöst.)
• • Abgleiten des gesamten Deckwerks (Das Deckwerk gleitet als Ganzes auf der sogenannten Filterschicht ab, oder das Deckwerk mitsamt der Filterschicht gleitet als Ganzes auf dem Dammkörper ab.)
• • Ausbrechen des Deckwerks (Das Deckwerk bricht oberhalb eines sogenannten Querriegels aufgrund des Zusammenwirkens der hohen Schub- und Liftkräfte aus.).

However, overflowable dams also have disadvantages that are known per se and described below (see also Fig.2 ):

• • Erosion of a single stone (A single stone is released from the composite.)
• • Slip of the entire revetment (The revetment glides as a whole on the so-called filter layer, or the revetment together with the filter layer glides as a whole on the dam body.)
• • Breaking of the revetment (The revetment breaks above a so-called crossbar due to the interaction of high shear and lift forces.).

In stone / rock fillings, the stones are not set, but poured loose with a certain strength. Ripples are sensitive even at low discharge changes. Due to the rearrangement of rocks, erosion gullies can form, which leads to a runoff concentration.

In contrast to the stone set, the flow through the rock fill plays an essential role. Rock fillings are used in hydraulic engineering for economic reasons. At the stone set, the stones are set individually. The fill is created by pouring and distributing the stones.

In order to obtain an economic riprap, the life of its main elements - riprap, filter layer and substructure - must be properly matched. Low costs are only present if the substructure and the riprap as well as any existing filter layer between riprap and substructure have the longest possible service life.

The proliferation of flood events and higher flood discharge rates mean that overflowable dams and dikes are more heavily used and riprap must be renewed more often.

In the case of coherent revetments, the individual elements of the revetment are durably stuck together by design measures and are therefore resistant to erosion. The design is done for the connected revetment. Dimensioning is the definition of a measure based on objective criteria during planning. The criteria can be based on experience, take into account physical laws or based on legal requirements. The assessment bases and procedures are regularly laid down in the technical regulations and the national and international standards. The starting point of the dimensioning process are the requirements that are placed on the object to be dimensioned. The aim of the design is to determine the necessary and optimal size or load capacity of a component based on a calculation process or a table. The design is documented in writing for testing purposes (if required).

In the case of a linked revetment, the entire component, that is to say the ballast currently associated with bitumen (mastic), is considered as one piece, since the monoliths are firmly connected to each other.

Mastic gravel can be referred to as "bitumen-bound single-grain chippings" that can be used to make a porous revetment. This material has been used in hydraulic engineering for many years in the area of embankment and embankment protection on riverine waters. It is a drainable and coherent revetment material. The strong bond of the individual grains is made by the bitumen mortar. In the production of masti-gravel the building materials grit (mostly limestone), bitumen, filler, medium sand and fibrous materials are usually used.

The disadvantage of mastic-gravel is the fact that bitumen changes its elasticity, hardness and adhesion, in particular under UV irradiation, whereby in the case of overflow individual stones can be released from the revetment. As a result, the ballast is actually the weakest main element of the flood overflow. The improvement of the Schottder properties is an important task to ensure a sufficient service life of the riprap on overflowable dams and dykes.

Task was therefore to fix the ballast stones on overflowable dams and dykes so that the aforementioned disadvantages are avoided without the measures are too complicated and too expensive for this and the process is too lengthy.

This task could be solved by the ballast consolidation according to the invention by producing coherent cover layers.

The invention relates to partially expanded or fully expanded ballast composites on overflowable dam / dyke bodies, which are characterized in that the ballast composites of ballast stones and polyurethane foam (PUR foam), which is located between the ballast stones exist.

As polyurethane foam, rigid foams or semi-rigid foams based on polyurethane are preferably used. Foamed solid polyurethane based systems can also be used. The foams have a sufficient resistance to deformation and, moreover, have a sufficiently high compressive strength. Another advantage of the polyurethane material used is that it can be varied within wide limits as a function of the external circumstances with regard to pressure resistance, reaction time and pot life via the composition of the components.

1. a) ein oder mehreren Isocyanatverbindungen aus der Gruppe bestehend aus Polyisocyanaten mit einem NCO-Gehalt von 28 bis 50 Gew.-% und NCO-Prepolymeren mit einem NCO-Gehalt von 10 bis 48 Gew.-% aus Polyisocyanaten mit einem NCO-Gehalt von 28 bis 50 Gew.-% und Polyetherpolyolen mit einer Hydroxylzahl von 6 bis 112, Polyoxyalkylendiolen mit einer Hydroxylzahl von 113 bis 1100 oder Alkylendiolen mit einer Hydroxylzahl von 645 bis 1850 oder Gemischen daraus und
2. b) einer Polyolkomponente bestehend aus einem oder mehreren Polyetherpolyolen mit einer Hydroxylzahl von 6 bis 112 und einer Funktionalität von 1,8 bis 8 in Gegenwart von
3. c) 0 bis 26 Gew.-%, bezogen auf die Reaktionskomponenten b) bis g), eines oder mehrerer Kettenverlängerungsmittel mit einer Hydroxyl- oder Aminzahl von 245 bis 1850 und einer Funktionalität von 1,8 bis 8, und
4. d) 0,05 bis 5 Gew.-%, bezogen auf die Reaktionskomponenten b) bis g), eines oder mehrerer Treibmittel,
5. e) 0 bis 5 Gew.-%, bezogen auf die Reaktionskomponenten b) bis g), eines oder mehrerer Katalysatoren,
6. f) 0 bis 50 Gew.-%, bezogen auf die Reaktionskomponenten b) bis g), eines oder mehrerer Füllstoffe und
7. g) 0 bis 25 Gew.-%, bezogen auf die Reaktionskomponenten b) bis g), eines oder mehrerer Hilfs- und/oder Zusatzstoffe,

wobei die Kennzahl des Reaktionsgemisches im Bereich von 70 und 130 liegt.The polyurethane foam used may be closed or open-celled. The polyurethane foam is preferably elastic, long-term stable, rot-proof and resistant to vermin. Particularly preferred as the polyurethane foam between the ballast stones, a reaction mixture is used

1. a) one or more isocyanate compounds from the group consisting of polyisocyanates having an NCO content of 28 to 50 wt .-% and NCO prepolymers having an NCO content of 10 to 48 wt .-% of polyisocyanates with a NCO content of 28 to 50 wt .-% and polyether polyols having a hydroxyl number of 6 to 112, polyoxyalkylene diols having a hydroxyl number of 113 to 1100 or alkylene diols having a hydroxyl number of 645 to 1850 or mixtures thereof and
2. b) a polyol component consisting of one or more polyether polyols having a hydroxyl number of 6 to 112 and a functionality of 1.8 to 8 in the presence of
3. c) 0 to 26 wt .-%, based on the reaction components b) to g), one or more chain extenders having a hydroxyl or amine number of 245 to 1850 and a functionality of 1.8 to 8, and
4. d) from 0.05 to 5% by weight, based on the reaction components b) to g), of one or more blowing agents,
5. e) 0 to 5% by weight, based on the reaction components b) to g), of one or more catalysts,
6. f) 0 to 50 wt .-%, based on the reaction components b) to g), one or more fillers and
7. g) 0 to 25% by weight, based on the reaction components b) to g), of one or more auxiliaries and / or additives,

wherein the ratio of the reaction mixture is in the range of 70 and 130.

The ballast composite according to the invention is mounted on the substructure of the dyke body, preferably on a filter layer which is located on the substructure of the dyke body. The filter layer is used for drainage (see also Fig.3 ).

1. 1) Schottersteine auf die Deich-/Dammkörper aufgeschüttet werden und
2. 2) zwischen die aufgeschütteten Schottersteine ein Reaktionsgemisch zur Herstellung eines Polyurethanschaumstoffes appliziert wird.

Another object of the invention is a method for solidifying the ballast stones (rock fillets) on overflowable dyke / dam bodies, wherein

1. 1) ballast stones are poured on the dyke / dam body and
2. 2) between the poured ballast stones, a reaction mixture for producing a polyurethane foam is applied.

Preferably, the aforementioned reaction mixture is used in the process. The reaction mixture is applied to the filter layer, as far as it is present on the substructure of the dam / dike body.

The ballast stones of the bed are connected by the introduced by means of a suitable apparatus reaction mixture, that is, by the resulting polyurethane foam to a holistic ballast structure (ballast composites). The adhesion of the polyurethane foam to the ballast stones, the structure density of the composite and the water permeability are good.

After the curing of the reaction mixture, the forces introduced by the overflow of the water can be transferred to the subsurface via the partially expanded or fully expanded ballast compounds on the overflowed dam / dyke bodies, so that the revetment (the ballast bed) slips or breaks or a single ballast stone is released avoided or at least made more difficult.

To apply the polyurethane, the two reaction components (polyisocyanate component and polyol component) are conveyed separately by means of a suitable apparatus (eg reaction casting machine) up to or above the bedrock, where they are continuously combined in a static or dynamic mixer and introduced into the bed via the spaces between the stones eg introduced by casting or spraying, where it hardens with foaming.

The polyol component preferably contains blends of polyether polyols with or without the use of hydroxyl group-containing fatty derivatives such as castor oil. Hydroxyl-containing fatty derivatives, in particular castor oil, increase the bondability and adhesive strength and, in addition, the flexibility of the polyurethane. The foaming of the reaction mixture is carried out in a maximum of a few minutes.

The partially expanded bedrock or riprap on the overflowable dams and dykes is solidified by introducing the flowable, foamable polyurethane reaction mixture into the bed of the dam / dyke.

The reaction mixture is added depending on the height of the riprap at the application site in preferably an amount which is greater, the further up the application site is in the riprap. Wherein the mixture is adjusted such that the foaming process does not begin until the front of the mixture flowing downwards within the riprap has reached the bottom of the riprap. The foaming then takes place within the riprap from bottom to top.

The flowable, foamable reaction mixture is adjusted so that the foaming process takes place only after a certain time after introduction of the mixture into the riprap. Such, the foaming process retarding properties of the reaction mixture are possible by suitable choice of the corresponding components and additives for the flowable and foamable reaction mixture. Foaming usually takes place from bottom to top, ie to the topmost layer of the riprap. For UV protection of the near-top region of the foam, it may additionally be expedient to apply a further loose rock fill to the revetment thus produced.

To condition the riprap, in particular as preparation for carrying out the method according to the invention, it is expedient to proceed by introducing hot air into the riprap from above, which exits laterally, determining the relative humidity of the exiting air and ending the process of heating the riprap if the mean humidity is less than a preset threshold.

By expelling the moisture from the riprap, improved conditions are created for the subsequent foaming. The heat input into the riprap can be controlled depending on the exiting humidity by the humidity of the outgoing rock from the backfill air is measured in several places, the heating of the riprap is terminated when the average humidity is less than a predetermined threshold.

• • auf dem Untergrund eine elastische Drainagematte als Filter angeordnet werden kann,
• • auf der Drainagematte eine Steinschüttung aus einzelnen Schottersteinen, die zwischen sich Hohlräume aufweisen, gebildet werden kann,
• • zur Lagefixierung der Steinschüttung in die Hohlräume zwischen den Einzelsteinen der Schüttung erfindungsgemäß ein schäumbares PUR-Material eingebracht wird.

With the method according to the invention for introducing a flowable, foamable reaction mixture from above into the riprap of the overflowable dams and dykes, it is possible to realize a method for producing a coherent revetment on a suitable substrate, in which

• • on the ground an elastic drainage mat can be arranged as a filter,
• • a riprap of individual ballast stones, which have cavities between them, can be formed on the drainage mat,
• • According to the invention a foamable PUR material is introduced for fixing the position of the riprap in the cavities between the individual stones of the bed.

For the chemical reaction in the foam formation, it is advantageous if the riprap has been heated before the introduction of the foamable reaction mixture, or has a higher temperature, which may be given depending on the ambient conditions without heating by an additional heat source.

The main problem of the known riprap on overflowable dams and dykes (the extraction of individual stones from the revetment and thus the under-rinsing and slipping of the entire revetment) can thus be prevented according to the invention that after completion of a new or a renewed or a revitalized revetment ( Riprap) this is foamed with foam material in the spaces between the ballast stones.

Use in humid weather does not harm, but promotes the foaming process, provided that a certain moisture level is not exceeded.

The ballast stones of the revetment are connected by the introduced polyurethane foam together to form a holohedral structure or a coherent revetment. The adhesive strength of the foam on the ballast stone and the structure density of the foam can be of the order of magnitude of the maximum load entry in the overflow case, plus a safety factor.

To improve the adhesion of the foam to the individual stones, it may be expedient to clean the stones before introducing the reaction mixture. This can be done by means of a high-pressure cleaner, by washing with water or, in particular, with new stones by the naturally occurring rain. Thereafter, as described above, wherein after completion of the riprap of the new or the renewed or the revitalized revetment, this is foamed with foam material.

After curing of the foam, all forces occurring in the overflow case can be transmitted via the ballast stones via the immobilized, coherent revetment. The foam serves to stabilize the position of the individual stones.

Since the foam consists of a large number of pores, the closing of the cavities does not result in a rigid ballast compound. Rather, it creates an elastic composite with many shock absorbers, whereby the longevity of the revetment, especially at frequent overflows is significantly increased.

The illustration 1 shows both a dam with freeboard (1) and an overflowable dam without freeboard (2). The difference between the dam (1) and the accumulation target (3) of the water (5) is referred to as freeboard (4).

The Figure 2 shows an overflowed dam with the base (10), in which the water (5) flows over the dam crown. In (6) a stone is released from the riprap (9), at (7) the revetment breaks and at (8) the revetment slides below the crossbar (12).

The Figure 3 shows an enlarged section Figure 2 with an additional filter layer (11).

Claims (5)

Partly expanded or fully expanded crushed stone compounds on overflowable embankment / dyke substructure, characterized in that the ballast composites of ballast stones and polyurethane foam (PUR foam), which is located between the ballast stones exist. Gravel composites according to claim 1, characterized in that a reaction mixture is used as polyurethane foam between the ballast stones a) one or more isocyanate compounds from the group consisting of polyisocyanates having an NCO content of 28 to 50 wt .-% and NCO prepolymers having an NCO content of 10 to 48 wt .-% of polyisocyanates having an NCO content of 28 to 50 wt .-% and polyether polyols having a hydroxyl number of 6 to 112, polyoxyalkylene diols having a hydroxyl number of 113 to 1100 or alkylene diols having a hydroxyl number of 645 to 1850 or mixtures thereof and b) a polyol component consisting of one or more polyether polyols having a hydroxyl number of 6 to 112 and a functionality of 1.8 to 8 in the presence of c) 0 to 26 wt .-%, based on the reaction components b) to g), one or more chain extenders having a hydroxyl or amine number of 245 to 1850 and a functionality of 1.8 to 8, and d) from 0.05 to 5% by weight, based on the reaction components b) to g), of one or more blowing agents, e) 0 to 5% by weight, based on the reaction components b) to g), of one or more catalysts, f) 0 to 50 wt .-%, based on the reaction components b) to g), one or more fillers and g) 0 to 25 wt .-%, based on the reaction components b) to g), one or
several auxiliaries and / or additives,
wherein the ratio of the reaction mixture is in the range of 70 and 130. Method for solidifying the ballast stones (rock fillings) on overflowable dyke / dam bodies, wherein 1) ballast stones are poured on the dike / dam substructure and 2) between the poured ballast stones, a reaction mixture for producing a polyurethane foam is applied. A method according to claim 3, wherein prior to the application of the ballast stones, a filter layer is applied to the dyke / dam substructure. The method of claim 3, wherein the reaction mixture contains the following components a) one or more isocyanate compounds from the group consisting of polyisocyanates having an NCO content of 28 to 50 wt .-% and NCO prepolymers having an NCO content of 10 to 48 wt .-% of polyisocyanates having an NCO content of 28 to 50 wt .-% and polyether polyols having a hydroxyl number of 6 to 112, polyoxyalkylene diols having a hydroxyl number of 113 to 1100 or alkylene diols having a hydroxyl number of 645 to 1850 or mixtures thereof and b) a polyol component consisting of one or more polyether polyols having a hydroxyl number of 6 to 112 and a functionality of 1.8 to 8 in the presence of c) 0 to 26 wt .-%, based on the reaction components b) to g), one or more chain extenders having a hydroxyl or amine number of 245 to 1850 and a functionality of 1.8 to 8, and d) from 0.05 to 5% by weight, based on the reaction components b) to g), of one or more blowing agents, e) 0 to 5 wt .-%, based on the reaction components b) to g), one or more catalysts f) 0 to 50 wt .-%, based on the reaction components b) to g), one or more fillers and g) 0 to 25 wt .-%, based on the reaction components b) to g), one or
several auxiliaries and / or additives,
wherein the ratio of the reaction mixture is in the range of 70 and 130.

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