RU2441112C1 - Method to liquidate periglacial lake with risk of breakthrough - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method includes development of an outlet canal in a moraine brattice. The outlet canal is deepened to the water level in the lake. Afterwards the lake water is discharged along a U-pipe laid at the level of the canal bottom. Inlet and outlet pipe portals are arranged accordingly on an upper slope under the lake water level and at the lower slope of the moraine brattice below the inlet portal level. As the lake water level reduces, the outlet canal is again deepened with subsequent reinstalling of the U-pipe. Cycles are repeated until the bottom of the outlet canal reaches the bottom of the periglacial lake with risk of breakthrough and the latter is liquidated, besides, periodical embedding of the outlet channel is done alternately - in turns at both shores of the outlet canal.

EFFECT: prevention of hazardous calamities.

Description

The present invention relates to the field of mountain hydrology and the prevention of dangerous natural phenomena and can be used to prevent the occurrence of mudflow of glacial genesis.

There is a method of preventing mudflow of glacial and mixed genesis, including the device of a trench spillway (channel) through a protective wall (lake bridge) of a breakthrough periglacial lake [1, p. 7, table; p.9, p.3.32].

A disadvantage of the known method for preventing mudflow of glacial genesis is the low reliability of safe discharge of water from a breakthrough lake due to the high probability of catastrophic mudflows and floods along the channel of a seleniferous river, due to the fact that when dumping water through a trench spillway in the form of a channel in a moraine bridge with a deepened bottom below the water level erosion erosion of incoherent moraine soil occurs in the lake. With large volumes of water in a breakthrough lake and increasing flow rates in the outlet channel, fine-grained particles are washed off first with the subsequent washing off of larger particles and stones. Subsequently, the erosion process acquires an intensifying and uncontrolled character with a linearly erosive deepening of the bottom of the outlet channel. The latter sharply increases the flow rates and rates of the discharged water flow, which takes on a landslide character of a developing breakthrough of the moraine lintel as a result of progressive erosion of the bottom (in depth) and slopes (in width) of the trench spillway (channel) in the sheathing shaft due to increasing values of the depth and flow rate of the overflow water flow with salvo discharge of the main water mass of the lake and the occurrence of mudflow.

There is a method of preventing mudflow of glacial genesis, including the device of a siphon spillway through a protective bridge of the lake [1, p.9, p.3.32].

The disadvantage of this method is the low reliability of its operation for the following reasons:

- a siphon spillway in high altitude conditions can drop the water level in a moraine lake to a maximum depth of 7-8 m, and then, provided that the top of the moraine lintel is slightly higher (up to 1.0-1.5 m) above the water level in the lake. Due to the fact that the water depth in glacial lakes can reach several tens of meters (up to 30 m or more, such as, for example, the breakthrough hazardous glacial lake Bashkara with a depth of 35 m), the work of a siphon spillway does not provide a complete discharge of lake water for its subsequent liquidation, but the remaining (large) part of the water mass of the lake poses a serious threat to the occurrence of mudflow;

- as a result of melting glaciers and precipitation, the water level in the lake rises again to critical levels with the threat of a moraine breakthrough, necessitating repeated measures to discharge the lake’s water, which does not completely eliminate the breakthrough glacial lake;

- in many cases due to the fact that the excess of the crest of the moraine lintel above the water level in the lake in places for safe discharge of water far exceeds the vacuum level of the suction of the siphon spillway, for example, the height of the corresponding protective wall on the lake. Bashkara is (40-50 m), the use of a siphon spillway laid over the crest of a moraine lintel is impossible due to hydraulic fracturing of the continuity of the water flow in the siphon pipe.

The closest to the claimed invention in terms of essential features is a method of eliminating a breakthrough hazardous priglacial lake, including the development of a discharge channel in the moraine lintel [2, p.26].

The disadvantage of this method is the low reliability of safe discharge of water of a breakthrough lake when it is liquidated due to the high probability of mudflow due to the fact that when water is discharged through a discharge channel in the moraine lintel, erosive erosion of incoherent moraine soil occurs. With large volumes of discharged water from a breakthrough lake and increasing flow rates in the discharge channel, fine-grained particles of soil are washed off first, followed by washing of larger particles, stones and boulders. Subsequently, the erosion process acquires an intensifying and uncontrolled character with a linearly erosive deepening of the bottom of the outlet channel. At the same time, the costs and rates of discharged water flow sharply increase, and the process of soil erosion acquires a landslide character with the subsequent breakthrough of the moraine lintel and the occurrence of mudflow.

When water is discharged through a channel in a moraine lintel with a bottom deepened below the water level at significant depths and volumes of water in a breakthrough lake, there is a real threat of a breakthrough of the protective moraine lintel for the following reasons:

- as a result of mechanical suffusion of the soil of the body of the enclosing shaft, its saturation with water and the hydrodynamic effect of the filtration flow on it;

- as a result of more intense destruction and collapse of the tongue (end section) of the glacier in contact with a higher water level of the lake, with a splash of part of the volume of water from the lake on top of the barrier wall with erosion of the latter;

- as a result of progressive erosion of the bottom (in depth) and slopes (in width) of the trench spillway (channel) in the moraine barrier, due to increasing values of the depth of flow of the iridescent water stream.

The technical result from the use of the claimed invention is to increase the reliability of safe water discharge during the liquidation of a breakthrough hazardous glacial lake.

The technical result is achieved by the fact that in the method of eliminating a breakthrough hazardous glacial lake, including the development of a discharge channel in the moraine bridge, the discharge channel is deepened to the water level in the lake, followed by discharge of water through a siphon pipe laid at the bottom of the channel with inlet and outlet tips located accordingly, on the upper slope below the lake water level and on the lower slope of the moraine bridge below the level of the inlet head, then, when the water level in the lake decreases by the amount of penetration At the bottom of the pipe, the outlet channel is again deepened to a new lowered water level of the lake, followed by reinstallation of the siphon pipe to a new level of the bottom of the channel for the next cycle of water discharge from the lake, while these cycles are repeated until the bottom of the outlet channel reaches the bottom of the explosive periglacial lakes with the liquidation of the latter, and periodic deepening of the outlet channel is carried out in an alternating manner - alternately along both banks of the outlet channel.

There is a well-known lowering method for the construction of underground structures, in which periodic tiered excavation of soil inside the lowering concrete well is carried out alternately with drainage, which allows lowering the bottom of the lowering well [3, pp. 292-296].

In the proposed method for eliminating a breakthrough periglacial lake, the outlet channel is deepened to the water level in the lake, which is discharged through a siphon pipe laid at the bottom of the channel with inlet and outlet heads located respectively on the uphill slope below the lake's water level and on the lower slope of the moraine bridge below the level of the inlet head, then, when the water level in the lake decreases by the amount of deepening of the inlet head of the pipe, the outlet channel is again buried to a new lower level of the lake water after by reinstalling the siphon pipe to a new level of the bottom of the outlet channel for the next cycle of water discharge from the lake, these cycles are repeated until the bottom of the outlet channel reaches the bottom of the breakthrough periglacial lake with the liquidation of the latter, and periodic deepening of the outlet channel is carried out in an alternating manner - alternately on both sides of the outlet channel.

The invention is illustrated in the figure, which schematically presents a system that implements the proposed method.

Figure a shows a cross section of a moraine lintel 1 of a breakthrough periglacial lake 2, in which a siphon pipe 4 with an inlet 5 and an outlet 6 heads located respectively on an uphill slope below the level is laid at the level of the bottom of the outlet channel 3 deepened to the water level ∇1 of lake 2 the water of lake 2 and on the lower slope of the moraine lintel 1 below the level of the inlet head 5. Here also shows the tiered deepening 7 of the bottom of the outlet channel 3 and siphon pipe 4, respectively, to lower water levels 8 of lake 2.

Fig. B shows a moraine bridge 1 with a cross section of the outlet channel 3 and siphon pipe 4 with a tiered deepening 7 of the bottom of the outlet channel 3 in an alternating manner - alternately on both sides of the outlet channel 3.

The method is implemented as follows. According to aerial and satellite images, hydrological surveys, field observations, etc. previously fix a breakthrough periglacial lake. Then, expeditionary studies determine the basic parameters of the lake (maximum depth and volume of water, lake area, types of barrier walls of the lake lintel, nature of nutrition, etc.), which makes it possible to assess the degree of danger of a catastrophic mudflow of glacial genesis during the breakthrough of the lake.

Based on the results of the assessment, a decision is made to eliminate the breakthrough periglacial lake 2 by a method that includes the development of a discharge channel 3 in the moraine lintel 1 with a depth to the water level in lake 2, after which the lake water is discharged through a siphon pipe 4 laid at the level 7 of the bottom of the discharge channel 3 with inlet and outlet heads located respectively on the uphill slope below the water level of lake 2 and on the downhill slope of the moraine lintel 1 below the level of the inlet head, then, when the water level in lake 2 decreases The depth of the inlet head of the pipe, the outlet channel 3 is again deepened to a new lowered water level from Lake 2, followed by reinstallation of the siphon pipe 4 to a new level of the channel bottom for the next discharge cycle of lake 2 water, while these cycles are repeated until the bottom of the outlet channel 3 does not reach the bottom of the explosive periglacial lake 2 with the liquidation of the latter, and periodic deepening of the outlet channel 3 is carried out in an alternating manner - alternately along both banks of the outlet channel.

The development of the bottom of the outlet channel 3 only to the water level in Lake 2 does not allow the development of uncontrolled discharge of water from Lake 2 through the outlet channel 3 with erosive erosion of the soil of the moraine bridge 1 with unpredictable consequences, while at the same time it allows you to position the siphon pipe 4 for water discharge from lake 2 at the level of the bottom of the outlet channel 3 with inlet and outlet heads located respectively on the uphill slope below the water level of lake 2 and on the downhill of the moraine lintel 1 below the level of inlet head 5. When lowering the water level in lake 2 by the depth of the inlet head of the pipe 5, the outlet channel 3 is again deepened to a new lower level of water of lake 2, after which the siphon pipe 4 is moved to a lower level of the bottom of the outlet channel 3 with the next regular cycle of discharge of water from lake 2 The indicated cycles are repeated until the bottom of the outlet channel 3 reaches the bottom of the breakthrough periglacial lake 2 with the liquidation of the latter. Periodic deepening of the outlet channel 3 is carried out in an alternating manner - alternately on both banks of the outlet channel 3, which allows to increase the efficiency of construction work for the next deepening of the channel due to the simultaneous discharge of lake 2 water through a siphon pipe 4 and reducing the time of elimination of a breakthrough priglacial lake.

The proposed method for the elimination of a breakthrough hazardous glacial lake can be fully used for the elimination of a breakthrough hazardous glacial lake in the language of the Bashkara glacier of the Adyl-su Kabardino-Balkaria gorge.

Information sources

1. SNiP 2.01.15-90. Engineering protection of territories, buildings and structures from dangerous geological processes. The main provisions of the design. M., 1997.32 s.

2. Perov V.F. Mudflows. Terminological dictionary. M .: Moscow State University, 1996, 46 p. - The prototype.

3. Ivanov E.S. Organization and production of hydraulic works. - 2nd ed., Revised. and add. - M .: Agproizdat, 1985.400 p.

Claims (1)

A method for eliminating a breakthrough hazardous glacial lake, including the development of a discharge channel in the moraine bridge, characterized in that the discharge channel is deepened to the water level in the lake, with subsequent discharge of water through a siphon pipe laid at the bottom of the channel with inlet and outlet tips located respectively on the top the slope under the lake water level and on the lower slope of the moraine bridge below the level of the inlet head, then when the water level in the lake decreases by the amount of deepening of the inlet head of the outlet pipe The canal is deepened again to a new lowered water level of the lake with the subsequent resetting of the siphon pipe to a new level of the canal bottom for the next cycle of water discharge from the lake, while these cycles are repeated until the bottom of the outlet canal reaches the bottom of the breakthrough periglacial lake with the liquidation of the last moreover, periodic deepening of the outlet channel is carried out in an alternating manner - alternately on both sides of the outlet channel.

Images