CN110295571B

CN110295571B - An overflow structure to prevent lake bursting in permafrost areas

Info

Publication number: CN110295571B
Application number: CN201910561017.7A
Authority: CN
Inventors: 穆彦虎; 马巍; 柴明堂; 周志伟; 张建明; 俞祁浩
Original assignee: Northwest Institute of Eco Environment and Resources of CAS
Current assignee: Northwest Institute of Eco Environment and Resources of CAS
Priority date: 2019-06-26
Filing date: 2019-06-26
Publication date: 2024-11-19
Anticipated expiration: 2039-06-26
Also published as: CN110295571A

Abstract

The present invention relates to an overflow structure for preventing lake bursting in permafrost regions, comprising a water retaining embankment (1) arranged on both sides of an overflow port and a buried culvert diversion structure arranged at the overflow port, wherein the water retaining embankment (1) comprises a fill layer (6) and a block stone layer (7) laid on its upper surface; the buried culvert diversion structure comprises a replacement fill layer (2), a thermal insulation layer (3) and a plurality of corrugated pipe culverts (4), wherein the replacement fill material of the replacement fill layer is a coarse granular soil material that is non-sensitive to frost heave, and the bottom surface thereof is located 1.5 m to 2 m below the upper limit of permafrost. The water retaining embankment structure can lift the upper limit of the lower permafrost, and effectively control the overflow position and range of the lake by utilizing the impermeability of the permafrost; the buried culvert diversion structure can effectively reduce the thermal erosion of the overflow water body on the lower permafrost, and prevent the foundation of the overflow structure from being unstable and the structure from failing. The application of the present invention can effectively ensure the long-term stability and effectiveness of the overflow structure, realize the orderly and controllable leakage of lakes in permafrost regions, and prevent the lake from bursting.

Description

Overflow structure for preventing lake from being broken in permafrost region

Technical Field

The invention relates to the technical field of hydraulic engineering in a frozen soil area, in particular to an overflow structure for preventing lake burst in a permafrost area.

Background

Research and monitoring show that the rainfall in permafrost areas of Qinghai-Tibet plateau increases significantly in recent years with warming of the climate. Under the background of climate warming and rainfall increase, the area and the water quantity of lakes in the permafrost region are continuously increased for many years, and the risk of overflow is prevented. Taking the cocoa-cri region as an example, the region develops in large sheets of continuous permafrost, and the climate shows a warm and humid trend in the last 50 years and is more obvious in 2000. The area of lake water and the amount of water in the area are continuously increased under the influence of the warming and humidifying process, and the risk of burst and overflow exists, for example, a burst event of a lake (Zhuo Naihu) occurs in month 2011 and 9. In permafrost areas, after the lake breaks, the back of the lake surface and the exposure of the lake bottom can cause a series of ecological environment problems. Meanwhile, free falling flood discharge water can cause serious thermal erosion to permafrost in Hong Dao, cause surface subsidence and can cause serious threat to engineering structures along the line.

Unlike conventional soil thawing, the strength of frozen soil is closely related to temperature conditions for many years. In the prior art, the concrete overflow structure has the problem of hydration heat in the construction process, and can cause remarkable thermal disturbance to surrounding permafrost, thereby causing foundation instability and structural failure of the overflow structure. Meanwhile, under the condition of long-term water passing, normal running water carrying heat can generate continuous thermal erosion on frozen soil under a conventional overflow structure for many years, so that the temperature rise and the melting and the strength loss of the frozen soil are caused, and the foundation instability and the structural failure of the overflow structure can be also caused.

Disclosure of Invention

The invention aims to solve the technical problem of providing an overflow structure for preventing a lake from being broken in a permafrost region, so as to solve the technical problems of short-term and long-term thermal erosion of concrete hydration heat and overflow water body to permafrost underlying a conventional diversion structure in the prior art, and further to cause instability of a foundation of the diversion structure and structural failure.

In order to solve the above problems, the overflow structure for preventing lake burst in permafrost region of the present invention comprises: the water retaining cofferdam and the buried culvert diversion structure are arranged at the two sides of the overflow port, and are in a state of high at the two sides and low at the middle; the water retaining bank comprises a filling layer and a block stone layer paved on the upper surface of the filling layer; the buried hidden culvert diversion structure comprises a filling layer, an insulating layer and a plurality of corrugated culverts, wherein the filling layer, the insulating layer and the corrugated culverts are arranged from bottom to top, the filling layer is filled with frost heaving insensitivity coarse-grained soil, and the bottom surface of the filling layer is located below the upper limit of permafrost by 1.5-2 m.

Preferably, the buried hidden culvert guide structure further comprises a reinforced bar stone cage layer arranged on the upper portion of the corrugated culvert, wherein the thickness of the reinforced bar stone cage layer is 0.5-0.8 m, and the grain size of the used stone is 20-30 cm.

Preferably, the length of the water retaining bank is not less than 20m, the thickness of the filling layer is not less than 2.5m, the top width is 1.5-2.0 m, and the slope is laid from the top according to the ratio of 1:1.2-1.5.

Preferably, the filler of the filling layer is frost heaving insensitivity coarse granule soil material.

Preferably, the thickness of the stone layer is 0.5-0.8 m, and the grain size of the stone material is 6-20 cm.

Preferably, the heat preservation wraps around the corrugated pipe culvert.

Preferably, the corrugated pipe culvert is a metal corrugated pipe for a culvert, the thickness is 2 mm-8 mm, and the diameter is 0.5 mm-1 m.

Compared with the prior art, the invention has the following advantages:

1. In the invention, the water retaining banks are arranged at two sides of the overflow port and comprise filling soil and overlying stones, (1) the overlying stones increase the heat dissipation of the permafrost at the lower part by utilizing the convective heat exchange process of low-temperature air in cold seasons, and (2) the heat resistance of the filling soil and the overlying stones can reduce the heat absorption of the permafrost at the lower part in warm seasons. Therefore, the upper limit of the permafrost at the lower part can be obviously lifted after the water retaining bank is built, and the overflow position and range of the lake can be effectively controlled by utilizing the water impermeability of the permafrost and the water retaining bank.

2. In the invention, the buried hidden culvert guide structure comprises a filling layer, a heat preservation layer and a series of corrugated culverts, (1) the filling layer can enhance the basic bearing capacity of the overflow structure, and effectively reduce frost heaving and thawing deformation; (2) The heat insulation layer can effectively isolate heat exchange between the overflow water body and the permafrost at the lower part, and maintain the heat condition of the permafrost at the lower part of the structure under the condition of water passing, so that the long-term stability and the effectiveness of the overflow structure are ensured; (3) The corrugated pipe culvert can realize the controllable leakage of the overflow water body, avoids the heat disturbance of hydration heat to surrounding permafrost in the construction process of the conventional concrete diversion structure, has the characteristics of light weight, good durability and the like compared with other prefabricated pipe culverts (such as concrete pipe culvert), and more importantly, the corrugated pipe culvert is tightly contacted with surrounding soil body, has strong foundation deformation capacity under the cyclic freezing and thawing action, and thus has good long-term stability.

In conclusion, under the comprehensive actions of the water retaining bank and the buried hidden culvert diversion structure, the application of the invention can effectively control the overflow position of the lake in the permafrost region and the long-term stability and effectiveness of the overflow structure, avoid the long-term thermal erosion of the overflow water body to permafrost at the lower part, realize the orderly and controllable leakage of lake water and prevent the lake from being broken.

3. The invention further comprises a reinforced bar stone cage layer arranged at the upper part of the corrugated pipe culvert, which can prevent the phenomenon that the lower heat-insulating layer and the corrugated pipe culvert layer are destroyed by the overflow water body under the condition that the overflow water body suddenly increases due to heavy rainfall in summer or other factors, and simultaneously reduce the damage of the heat-insulating layer and the corrugated pipe culvert layer caused by the ice pushing action in winter, thereby further enhancing the overall stability of the overflow structure.

Drawings

The following describes the embodiments of the present invention in further detail with reference to the drawings.

Fig. 1 is a schematic structural diagram of an overflow structure according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a water dam in an overflow structure according to an embodiment of the invention.

FIG. 3 is another schematic cross-sectional view of a water dam in an overflow structure according to an embodiment of the invention.

In the figure: 1-water retaining bank, 2-replacement filling layer, 3-heat preservation layer, 4-corrugated pipe culvert, 5-overflow port surface layer filling soil, 6-filling layer, 7-block stone layer and 8-reinforcement block gabion layer.

Detailed Description

Referring to fig. 1-2, an embodiment of the present invention provides an overflow structure for preventing lake break in a permafrost region, which mainly includes a water retaining dam 1 disposed at two sides of an overflow port and a buried culvert diversion structure disposed at the overflow port, wherein the two sides are in a high-middle low state; it can be understood that the buried hidden culvert guide structure is arranged below the surface layer filling soil 5 of the overflow port, and the flowing water overflows from the corrugated culvert 4 in the buried hidden culvert guide structure.

The water retaining bank 1 comprises a filling layer 6 and a block stone layer 7 paved on the upper surface of the filling layer 6. The height of the filling layer 6 is determined according to the topography at two sides of the overflow port, the requirement is not less than 2.5m, the top width is 1.5-2.0 m, and the slope is laid from the top according to the ratio of 1:1.2-1.5, so that the stability is ensured. The thickness of the stone layer 7 is 0.5-0.8 m, the stone material is broken stone or stone block, and the grain size is 6-20 cm. The length of the water retaining bank 1 is determined according to the local topography, and the two sides of the overflow port are required to be not less than 20m.

The buried hidden culvert guide structure comprises a filling layer 2, an insulation layer 3 and a corrugated culvert 4, wherein the filling layer 2 is positioned below the insulation layer 3 and the corrugated culvert 4, and the insulation layer 3 is arranged at the bottom of the corrugated culvert 4 and the top of the filling layer 2. In order to further enhance the stability of the buried hidden culvert diversion structure, the buried hidden culvert diversion structure can further comprise a reinforced bar stone cage layer 8 arranged at the upper part of the corrugated pipe culvert 4. The reinforced bar gabion layers 8 are arranged side by side along the overflow direction, the width and the length are the same as the length of the corrugated pipe culvert, the thickness is 0.5-0.8 m, and the grain size of the used stone is 20 cm-30 cm.

The filler of the filler exchange layer 2 is frost heaving insensitive coarse-grained soil, the thickness is determined based on the upper limit of permafrost at the lower part of the overflow port, and the filler exchange layer is required to be replaced and filled 1.5-2 m below the upper limit of permafrost from below the heat preservation layer 3. By adopting the materials and the arrangement mode, frost heaving and thawing deformation can be effectively reduced, and the basic bearing capacity and stability of the overflow structure are enhanced. Similarly, the filling materials of the filling layer 6 in the surface layer filling 5 of the overflow port and the water retaining bank1 can also adopt frost heave insensitive coarse particle soil materials, so that the stability of the whole overflow structure is further improved.

The heat preservation layer 3 can be wrapped around the corrugated culvert 4 as shown in the figure, and can be arranged at the bottom of the corrugated culvert 4 and the top of the filling layer 2, but the former is better in terms of heat preservation and heat insulation effects. The width of the heat preservation layer 3 is determined according to the number and the diameter of the corrugated culverts 4, and the length is the same as the length of the corrugated culverts 4. In practical application, the heat insulation layer 3 can be made of XPS heat insulation material, and the heat conductivity coefficient is not more than 0.03W.m ^-1.K^-1, and the thickness is 10cm to 15cm.

The corrugated culverts 4 are arranged side by side along the overflow direction, the diameter and the number are determined according to the overflow flow of the lake on the basis of considering the topography of the overflow port, and the length is determined according to the topography of the overflow port and the distance from the overflow port to the downstream river (flood). In practical application, the corrugated pipe culvert 4 is a metal corrugated pipe for culverts, the material is Q235 or SS400 hot rolled steel plate, the thickness is 2mm to 8mm, and the diameter of the pipe culvert is 0.5m to 1m.

Based on the disclosure, in the actual construction process of the overflow structure, the heat preservation layer 3 and the corrugated pipe culvert 4 are prefabricated for factories and spliced on site, so that the on-site construction cost is saved.

The materials of the parts related by the invention are common geotechnical materials, the construction cost is low, the construction procedures are few, and the post maintenance is simple. The whole structure is quick and portable in construction, less manpower and machinery are needed, and the disturbance of the construction process to surrounding permafrost is small.

The technical scheme provided by the invention is described in detail. The principles and embodiments of the present invention have been described herein with reference to specific examples, the above examples being provided only to facilitate understanding of the structure of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.

Claims

1. An overflow structure for preventing burst of lakes in a permafrost region, comprising:

The water retaining cofferdam (1) arranged at two sides of the overflow port and the buried hidden culvert diversion structure arranged at the overflow port are in a state of high at two sides and low at the middle;

The water retaining bank (1) comprises a filling layer (6) and a stone block layer (7) paved on the upper surface of the filling layer (6);

the buried hidden meaning diversion structure comprises a filling layer (2), an insulating layer (3) and a plurality of corrugated pipe culverts (4) arranged along the overflow direction from bottom to top, wherein the filling material of the filling layer (2) is frost heaving insensitive coarse-grained soil, and the bottom surface of the filling layer is 1.5-2 m below the upper limit of permafrost;

the buried hidden culvert diversion structure further comprises a reinforced bar stone cage layer (8) arranged at the upper part of the corrugated pipe culvert (4), wherein the thickness of the reinforced bar stone cage layer is 0.5-0.8 m, and the grain diameter of the used stone is 20-30 cm;

The length of the water retaining bank (1) is not less than 20m, the thickness of the filling layer (6) is not less than 2.5m, the top width is 1.5-2.0 m, and the slope is laid from the top according to the ratio of 1:1.2-1.5;

the filler of the filler layer (6) is frost heaving insensitive coarse-grained soil;

The thickness of the stone block layer (7) is 0.5-0.8 m, and the grain diameter of the stone material is 6-20 cm;

the heat preservation layer (3) is wrapped around the corrugated pipe culvert (4);

The corrugated pipe culvert (4) is a metal corrugated pipe for a culvert, the thickness is 2 mm-8 mm, and the diameter is 0.5 mm-1 m.