Dam relief

Description

Technical field

[0001] The invention relates to a method for relieving the pressure on an existing or new dam by integrating it into a dam structure assembly. The invention further relates to a dam structure assembly comprising a main dam and a relief dam. State of the art

[0002] The invention relates to a method for relieving the pressure on a main dam wall of a dam system. Dams are also known as reservoirs, weirs, or dam walls and are often, but not exclusively, part of the reservoir system of a hydroelectric power plant.

[0003] A dam can have various construction methods, such as gravity dams, arch dams, and buttress dams. Such construction methods are known to those skilled in the art. US 779,703 and FR 594,913 disclose a method and a dam arrangement according to the preamble of claim 1.

[0004] Due to their long service lives, ranging from decades to a hundred years, dams require renovation or even replacement. A complete renovation often necessitates shutting down the power plant for months or even years. During this time, electricity production is impossible, resulting in significant operational losses. Furthermore, the emptying of the reservoirs and the resulting lack of water capacity can create additional water management problems in the area.

[0005] Several methods are known for the rehabilitation of an existing dam structure. For example, particularly in the case of leaks in the ground area, concrete capsules can be connected to the dam structure, with the capsule being connected to the interior of the reservoir via a pipe in such a way that a counter-pressure is created inside the capsule.

[0006] In another option, a new dam is built downstream as a replacement, and once the new dam is completed, the old one is flooded. Experts are familiar with other techniques for the renovation or construction of dams.

[0007] The disadvantage of the known methods for new construction and complete renovation is that they are very complex and therefore expensive. Description of the invention

[0008] The object of the invention is to provide a method belonging to the aforementioned technical field for relieving existing or new dam structures, which is particularly cost-effective. In particular, the method makes it possible to carry out relieving without emptying the reservoir.

[0009] The solution to the problem is defined by the features of claim 1. According to the invention, a relief wall is built downstream of the main dam, which has a lower height than the main dam, wherein a relief lake is formed between the main dam and the relief wall in such a way that the resulting hydrostatic pressure forces on the main dam are reduced.

[0010] In the process of relieving an existing dam, a relief wall is built downstream of the main dam, which has a lower height than the main dam. Subsequently, a relief reservoir is created between the relief wall and the main dam.

[0011] The invention further relates to a dam structure arrangement comprising a main dam, wherein the dam structure arrangement includes a relief wall downstream of the main dam, which has a lower height than the main dam, wherein a relief lake is formed between the main dam and the relief wall in such a way that resulting hydrostatic pressure forces on the main dam are reduced.

[0012] The relief reservoir is preferably designed such that the water level in the relief reservoir lies within a range between the lowest point of the main dam on the reservoir side and the water level in the reservoir. While the water in the reservoir exerts pressure against the main dam, this pressure is at least partially compensated by a counter-pressure in the relief reservoir, resulting in a lower net pressure on the main dam. This relieves the pressure on the main dam. Instead of repairing the main dam, this structural measure can relieve the pressure on a main dam in need of repair. Depending on the design of the main dam, this can also strengthen it. If it is a gravity dam with a decreasing cross-section towards the top, the relief reservoir can exert a weight force on the main dam, which strengthens it or pushes it downwards.

[0013] The effects of the relief dam and the relief reservoir can be calculated as follows: For a quantitative estimate of the relief of the main dam, a constant width B is assumed for both dams from bottom to top. The static pressures in the upper reservoir and lower relief reservoir, respectively, increase linearly with the water depth.

[0014] The load on the main dam at the (theoretically) maximum fill level H of the reservoir is given by the resultant force (mean pressure). p ¯ = 1 2 ρgH ): F = p ¯ BH = 1 2 ρgBH 2 N

[0015] The relief of the main dam depends solely on the level of the discharge reservoir. At the (theoretically) maximum level h, which is equal to the height of the discharge dam, the relief force is calculated as follows: Δ F = 1 2 ρgBh 2 N

[0016] The resulting force acting on the main dam is reduced to F − Δ F = 1 2 ρgB H 2 − h 2 N

[0017] The degree of relief is then calculated. Δ F F = h H 2

[0018] For h / H A value of 0.5 indicates a reduction of 25%. For a still operational dam, such a reduction is considerable and therefore of great importance. For h / H = 0.7 The main dam will be relieved of approximately 50% of its load. In the case of the Fig. 2 With the replacement dam, the relief of the main dam is 100%.

[0019] Preferably, the relief reservoir has an open surface. This allows for a particularly simple construction, which in turn keeps the manufacturing process cost-effective. In some variations, the relief reservoir can also be closed; however, it is essential to ensure that no force-transmitting connection is formed between the relief dam and the main dam. These should be force-independent.

[0020] The height of the relief wall is between 30% and 95% of the height of the main dam, in particular between 35% and 60%.

[0021] The height of the relief wall is between 30% and 95% of the height of the main dam, measured from the lowest point on the ground of the main dam, in particular from the lowest point on the reservoir side of the main dam.

[0022] The crest of the relief wall lies at least 5% below the crest of the main dam.

[0023] The above method is preferably used to relieve the load on an existing main dam rather than to rehabilitate it. This allows an older, overloaded main dam to be relieved of stress, thus significantly extending its lifespan. Depending on the condition of the main dam requiring rehabilitation, it may only be partially rehabilitated, and the dam can also be raised if necessary.

[0024] In another preferred method, both the main dam and the spillway are newly constructed. This method is therefore also suitable for new construction projects where no main dam existed previously. This allows the main dam to be built more cost-effectively from the outset, as the operational load on the main dam is lower. Furthermore, more than one spillway can be constructed; in particular, a cascade of spillways is theoretically possible, with each subsequent one downstream having a lower height than the preceding one. It is irrelevant whether the main dam or the spillway is designed as a gravity dam, an arch dam, or a buttress dam – the method works with any type of main dam or spillway.

[0025] Preferably, the main dam and the spillway each include at least one reference point, allowing for the monitoring and regular inspection of any changes in the shape of the main dam and / or the spillway, as well as any displacement of the main dam and / or the spillway relative to each other. In some variations, the reference point may be omitted.

[0026] Preferably, the relief reservoir includes at least one intermediate floor. This can be used, for example, to create a swimming pool or similar structure. The intermediate floor is preferably anchored only on one side, for example, in the main dam, so that neither tensile nor compressive forces act between the main dam and the relief reservoir.

[0027] The relief reservoir between the main dam and the relief wall can be used in many different ways. For example, it can be used as a recreational facility, especially for water sports, as a swimming pool, and / or for fish farming or fishing. In other variations, the relief reservoir can also be used as a stilling basin. Experts are aware of further applications. Alternatively, the relief reservoir can also remain unused.

[0028] Further advantageous embodiments and combinations of features of the invention can be derived from the following detailed description and the entirety of the patent claims. Brief description of the drawings

[0029] The drawings used to illustrate the exemplary embodiment show: Fig. 1 a schematic representation of a cross-section through a gravity dam; Fig. 2 a schematic representation of a cross-section through a gravity dam, which, according to the prior art, is replaced by an arch dam; Fig. 3 a schematic representation of a cross-section through a gravity dam, a relief wall, and the relief reservoir; Fig. 4 a schematic representation of a cross-section through a gravity dam showing the compressive forces resulting from the relief reservoir; Fig. 5 a schematic representation of a cross-section through a gravity dam showing the reinforcing forces achieved due to the relief reservoir; Fig. 6 a schematic representation of a front view of the relief wall; Fig. 7 a schematic representation of a cross-section through a gravity dam where the construction material is used to reinforce the main dam instead of a relief wall; and Fig. 8 a schematic representation according to Fig. 3 , with intermediate floors inserted in the relief lake and reference points mounted on the two walls.

[0030] Basically, identical parts in the figures are marked with the same reference symbols. Ways to implement the invention

[0031] In the otherwise known Fig. 1 Figure 1 shows a gravity dam which, due to its long service life of decades to hundreds of years, requires refurbishment. Because the refurbishment necessitates draining the reservoir (2) and shutting down the power plant for months to years to generate electricity, and will therefore cause significant operating losses, the following measures are being considered: Fig. 2In certain cases, a replacement dam (4) is planned and built. The replacement dam (4), at the same height as the main dam (1), completely replaces the old dam (1), which usually remains and is later submerged. If the dam (1) is a listed historical monument, there would be discussions.

[0032] In the case of the main dam (1) requiring repair, the replacement dam (4) will incur high costs, depending on its size. Construction will also take several years.

[0033] To save costs and time, and in particular to avoid any interruption in electricity production, the existing dam (1), which is in need of repair and is referred to here as the main dam, will be reinforced and relieved of its load simultaneously at low construction costs. Instead of constructing the replacement dam (4) to at least the same height as the main dam (1), a lower-height relief dam (5) will be built according to Fig. 3The relief wall (5) is located downstream of the main dam (1). The minimum distance between the relief wall (5) and the main dam (1) can be arbitrarily small (e.g., down to 0.1 m). The maximum distance is generally unlimited, but depends primarily on the geographical location of the valley and the construction costs.

[0034] The space between the two dams (1, 5) is filled with water, creating a relief reservoir (6) with an open surface to the atmosphere. The water level of the relief reservoir (6) can be adjusted. Generally, the set water level remains constant. For specific purposes, a limited amount of inflow and outflow from the relief reservoir (6) is permitted, either continuously or over time.

[0035] The main dam (1), the spillway (5), and the spillway reservoir (6) form a dam structure (13, 14) with a spillway effect. The main dam (1) can be a gravity dam, an arch dam, or a dam of other design. In particular, the main dam (1) can be a new structure.

[0036] The fill level of the relief reservoir (6) determines the degree of relief of the main dam (1) (see above). The hydrostatic pressure forces (7) in the relief reservoir (6) counteract the pressure forces (3) on the main dam (1) in the corresponding area. This reduces the total pressure forces (8) on the main dam (1), see above. Fig. 4 . This is the most effective, since in a dam (1) the greatest load is always in the lower part of the wall.

[0037] The water in the relief reservoir (6) also ensures that the gravity dam (1) under consideration is further reinforced by the additional mass of the water (9) pushing the dam downwards ( Fig. 5 ). Both the reinforcement and the discharge of the main dam (1) depend on the fill level of the discharge reservoir (6). The reinforcement of a gravity dam (1), for example, is achieved by adding mass (9) of water after Fig. 5 . This also depends on the inclination of the outer wall of the dam (1).

[0038] For a still operational dam, a reduction in pressure of, for example, 20%–30% (reduction rate) is expected to be considerable and therefore of great importance. Even a complete refurbishment of the old dam (1) would not achieve a comparable result, or only with great difficulty.

[0039] The reinforcement and relief of the main dam (1) achieved by the relief wall (5) and the water-filled relief reservoir (6) depend solely on the water level of the relief reservoir (6). They are independent of the amount of water in the relief reservoir (6) and therefore of the distance between the two walls (1, 5). Theoretically, the relief wall (5) can be built arbitrarily close to the main dam (1), as long as the two walls are separated by the water in the relief reservoir (6).

[0040] Since the relief wall (5) is relatively low, it is subjected to relatively little stress from the water in the relief lake (6), so that the dam thickness can be kept small ( Figs. 3 and 4 ). Because of the additional narrowness of the valley ( Fig. 6In the lower valley area, significant savings in building materials (stones, concrete) can be achieved. Depending on the height of the relief wall (5), the construction volume of the relief wall (5) can be reduced, for example, to 1 / 2 to 1 / 8 of the construction volume of the replacement dam (4).

[0041] It should be noted that the reinforcement and relief of the main dam (1) achieved by the relief wall (5) and relief lake (6) are much greater than the effect of simply adding construction materials (5a) to an existing gravity dam ( Fig. 7 ). The case in Fig. 7 corresponds to a type of mechanical support or reinforcement instead of hydraulic relief of the main dam (1).

[0042] In the case of an old dam that has been classified as "worthy of preservation" by the heritage authorities, the dam remains visible and thus enjoys a certain degree of heritage protection.

[0043] In the event of a new construction of the main dam (1) using any possible design (gravity dam, arch dam, etc.), the dam (1) can be built correspondingly thinner if the relief dam (5) is constructed at the same time. The total amount of construction materials required is reduced accordingly. Constructing the relief dam (5) using the latest technology also provides the population with a greater sense of security.

[0044] The relief lake (6) with its open surface can be converted into a recreational facility such as an open-air swimming pool. To ensure safety, an intermediate floor (10) can be installed, e.g., made of slabs ( Fig. 8 ).

[0045] The water for electricity production will continue to be drawn from the upper reservoir (2). In the case of the old dam (1), which requires renovation, the existing pipeline system will remain in place. The water in the lower relief reservoir (6) is typically not used for electricity production.

[0046] The importance of the relief lake (6) in connection with the relief wall (5) lies in the fact that a relief rate of e.g. 25% to 90% (see above) can be achieved.

[0047] In special variants, a dam arrangement (13) consists of a main dam (1), a relief dam (5) and a relief reservoir (6) with a free surface, whereby the main dam (1) is often an old dam and therefore in need of repair.

[0048] The relief wall (5) is preferably installed at a low height, of any shape and thickness (wall thickness) downstream of the main dam (1), below the dam, weir and reservoir.

[0049] The height of the relief wall (5) is 30% to a maximum of 95% of the height of the main dam (1), with both walls being measured from the same elevation (12) of the lowest ground point of the main dam (1) ( Fig. 3 ).

[0050] The crest (upper edge) of the relief wall lies at least 5% above the height of the main dam (1) and below the crest of the main dam (1).

[0051] The relief reservoir (6) preferably has a free surface, wherein the free space between the main dam (1) and the relief wall (5) is fully or partially filled with water.

[0052] In the process for reinforcing and relieving the main dam (1), the hydrostatic pressure forces in the relief reservoir (6) counteract those in the reservoir (2). The relief reservoir (6) is preferably used wholly or partially for special applications such as a recreational facility, swimming pool, water sports, fish farming and fishing, as well as a water source for other experiments with specific objectives.

[0053] In the relief lake (6) one or more intermediate floors (10) are preferably constructed.

[0054] Preferably, in a dam structure arrangement (14) several reference points (11) are installed at the main dam (1) and the relief dam (5) in order to regularly monitor the deformation of and relative displacements between the two dams.

[0055] Within the framework of the dam structure arrangement (13) and method for relieving the main dam (1), the relief wall (5) and the relief lake (6) are preferably also used when the main dam (1) is new or is being newly constructed.

[0056] In summary, the invention provides a method for relieving existing dams, which avoids emptying the reservoir and simultaneously saves construction volume (stones and concrete).

Claims

1. Method for relieving a main dam (1) of a dam structure arrangement (14) of a reservoir, wherein the dam structure arrangement (14) comprises a main dam (1) for impounding a reservoir and a relief dam (5), wherein downstream of the main dam (1) a relief dam (5) is constructed which has a lower height than the main dam (1), wherein between the main dam (1) and the relief dam (5) a relief reservoir (6) is formed in such a manner that resulting hydrostatic pressure forces on the main dam (1) are reduced, characterized in that the structure height of the relief dam (5) is between 30% and 95% of the structure height of the main dam (1) and wherein a crest of the relief dam (5) lies at least 5% of the structure height of the main dam (1) below the crest of the main dam (1) and a water level in the relief reservoir (6) lies at least 5% of the structure height of the main dam (1) below a water level of the reservoir (2).

2. Method according to claim 1, characterized in that the relief reservoir (6) has a free surface.

3. Use of the method according to one of claims 1 or 2 for relieving an existing main dam (1) requiring rehabilitation instead of its complete rehabilitation.

4. Dam structure arrangement of a reservoir comprising a main dam (1), wherein the dam structure arrangement comprises, downstream of the main dam (1), a relief dam (5) which has a lower height than the main dam (1), wherein between the main dam (1) and the relief dam (5) a relief reservoir (6) is formed in such a manner that resulting hydrostatic pressure forces on the main dam (1) are reduced, characterized in that the structure height of the relief dam (5) is between 30% and 95% of the structure height of the main dam (1) and wherein a crest of the relief dam (5) lies at least 5% of the structure height of the main dam (1) below the crest of the main dam (1) and a water level in the relief reservoir (6) lies at least 5% of the structure height of the main dam (1) below a water level of the reservoir (2).

5. Dam structure arrangement according to claim 4, characterized in that the main dam (1) requiring rehabilitation can be partially rehabilitated, wherein the main dam (1) can also additionally be raised if required.

6. Dam structure arrangement according to claim 4 or 5, characterized in that the main dam (1) and the relief dam (5) each comprise at least one reference point by means of which a deformation of the main dam (1) and / or of the relief dam (5) as well as a displacement of the main dam (1) and / or of the relief dam (5) relative to one another can be monitored.

7. Dam structure arrangement according to claim 4 or 5, characterized in that the relief reservoir (6) comprises at least one intermediate floor.