CN108867569B - Natural dredging debris flow sand dam and application thereof - Google Patents
Natural dredging debris flow sand dam and application thereof Download PDFInfo
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Abstract
A natural desilting debris flow sand dam comprises a main dam body and an anti-scour auxiliary structure positioned on one side of the back surface of the main dam body, wherein the main dam body consists of non-overflow sections on the left side and the right side and an overflow section in the middle, the non-overflow sections are integrally formed in a concrete pouring mode, and the overflow section adopts a structure for assembling the dam body; the scour protection auxiliary structure is a combination of an auxiliary dam and a fender. When the method is used, the proportion of the deposits in the reservoir area which can be washed away is calculated firstly, and the dredging scale is determined; and (3) disassembling a corresponding number of prefabricated components according to the dredging scale, then excavating an overflow channel in the reservoir area, rapidly washing sediment in the reservoir area by utilizing the mountain torrents in the intermittent period of debris flow outbreak to carry out natural dredging, and reinstalling the disassembled prefabricated components after dredging is finished so as to finish the dredging work of the sand dam. The silt arrester of the invention solves the problems of difficult dredging of the reservoir area after the existing debris flow arresting dam is full of the reservoir, large investment and disposal of silt in the reservoir area when the design year is reached.
Description
Technical Field
The invention belongs to the field of debris flow disaster prevention and control and hydraulic engineering, and particularly relates to a debris flow sand dam for natural dredging and application thereof.
Background
The debris flow is a common geological disaster in mountainous areas, a large amount of solid matters strongly reform the channel and the main river terrain, extreme climates in mountainous areas of China frequently occur, the outbreak frequency of the debris flow disaster in a very large scale is higher and higher, and the disaster prevention situation is more severe. Therefore, the key problems in the current disaster prevention work are solving the difficult problems of the maximization of the disaster prevention benefit in the super-large-scale debris flow prevention and control project, the maintenance and management in the later period of the project and the like.
The sand dam is the most widely applied project in the debris flow treatment technology, has the functions of blocking sediment and regulating peak and controlling flow, and is divided into a gravity dam, a pile forest dam, an open type sand dam, a submerged dam and the like according to the structural form, however, after the sand dam operates for a certain period or experiences debris flow disasters of a certain scale, the possibility that the reservoir area is full of sediment and the sediment in the reservoir area breaks down when the project is damaged to generate secondary disasters can occur; meanwhile, after the blocking engineering reservoir area is full of silt, the sand blocking benefit is lost, and the flow control effect on later debris flow disasters is difficult to play. In order to realize the continuity of the disaster prevention benefits of the blocking engineering, the traditional blocking engineering usually needs to carry out dredging work after the warehouse is full, the economic investment is large, and in addition, the problem of how to deal with the silt of the blocking engineering warehouse area beyond the design age is also the problem in the current stage disaster prevention engineering. Therefore, the existing blocking technology has great limitation on the large-scale and high-frequency treatment of debris flow disasters.
Disclosure of Invention
The invention aims to provide a debris flow sand dam for natural dredging and application thereof, wherein concentrated water flow in the burst interval period of debris flow is utilized to quickly wash sediment in a reservoir area for natural dredging, so that the problems of high difficulty in dredging the reservoir area, high investment in financial and material resources and disposal of the sediment in the reservoir area when the design life of the sand dam reaches the limit after the reservoir is full of the existing debris flow sand dam are solved.
The invention is realized by the following technical scheme:
a natural desilting debris flow sand dam comprises a main dam body and an anti-scour auxiliary structure positioned on one side of the back surface of the main dam body, wherein the main dam body consists of non-overflow sections on the left side and the right side and an overflow section in the middle, the non-overflow sections are integrally formed in a concrete pouring mode, and the overflow section adopts a structure for assembling the dam body; the scour protection auxiliary structure is a combination of an auxiliary dam and a fender.
Furthermore, the safety reserve of the sand trap is more than 1.2 times of that of the traditional integral sand trap.
Furthermore, the upstream surface of the main dam body is step-shaped, the gradient of the upstream dam body is 1:0.75-1:1, and the downstream surface is vertical.
Furthermore, the width of the overflow section is determined by calculation according to the debris flow and the valley condition, when the width is not more than 20m, only the structure of the assembled dam body is adopted, and when the width exceeds 20m, the pile structure is adopted to separate the overflow section dam body so as to enhance the strength of the assembled dam body.
Furthermore, the assembled dam body is formed by splicing a plurality of prefabricated components in a mortise and tenon structure, each prefabricated component comprises a cuboid main body, and one side or two sides of each main body are provided with connecting parts.
Furthermore, an anchoring hole is formed in the main body of the prefabricated part, an anchor rod with matched size is arranged in the anchoring hole to connect and reinforce the assembly dam body, a sleeve is arranged in the anchoring hole, the anchor rod is fixed in the sleeve through grouting, the bottom end of the anchor rod is fixed on the non-overflow section, and the upper end of the anchor rod is an anchoring end;
the prestress N is calculated by adopting the following formula
In the formula: n-anchor prestress
τmax-calculating the maximum shear stress of the profile
A is the contact area of the joint of the concrete prefabricated parts.
Furthermore, an anti-scouring steel plate for increasing the integral anti-scouring capacity of the dam body is arranged on the upper surface of the overflow section.
Firstly, before dredging operation, calculating the maximum particle size and the scouring depth of natural scouring according to sediment dynamics analysis, calculating the proportion of deposits in a reservoir area which can be scoured away, and determining the dredging scale; secondly, disassembling the prefabricated parts with the matched number of overflow sections according to the dredging scale, then excavating an overflow channel in the reservoir area, rapidly washing sediment in the reservoir area by utilizing concentrated water flow in the intermittent period of debris flow explosion for natural dredging, and reinstalling the disassembled prefabricated parts after dredging is completed to complete the dredging work of the sand dam.
Furthermore, the dredging operation is performed in a step-by-step dredging sequence from upstream to downstream, and is performed when the last sand dam is not full of the reservoir, and the last sand dam is used as reserved safety reserve; before the prefabricated parts are disassembled, a groove is dug or a temporary diversion dike is built in the reservoir area, and the integral dredging speed of the reservoir area is accelerated in a water-restraining and sand-attacking mode.
Furthermore, when the dam body is disassembled and assembled, the one-time disassembly height of the most downstream sand retaining dam is controlled within the range of 0.1-0.2 times of the total dam height, the one-time disassembly height of the other sand retaining dams is controlled within the range of 0.2-0.5 times of the effective dam height, and the section of the disassembled gap is designed to be V-shaped, so that the scouring of silt is accelerated; when the anchor rod is disassembled, the anchoring end of the anchor rod is unfastened, the prefabricated part is disassembled, the integral anchor rod structure is taken off, and temporary anchor rods are applied to two sides of the overflow section to form a V-shaped discharge port; after dredging is completed, the temporary anchor rods are disassembled, the prefabricated parts are reassembled according to the surface damage degree, the prefabricated parts with serious surface damage are loaded at the middle lower part, and the prefabricated parts with complete surfaces are loaded at the flow surface of the sand dam.
The invention has the beneficial effects that:
according to the invention, the overflow section sand blocking dam is built into a detachable assembled structure, so that the silt accumulated in the reservoir area can be flushed away by utilizing the water flow in the intermission period of the debris flow, the defect that the reservoir area of the traditional sand blocking dam is filled with the silt and then is subjected to low-efficiency cleaning by using a large amount of manpower and financial resources is overcome, meanwhile, the traditional sand blocking dam needs to be reconstructed again when reaching the design year limit, and the cost is high.
The prefabricated part is the standard component, conveniently changes the use and dismantles the operation.
When desilting, utilize the convenience of the assembled structure of overflow section, form V type discharge opening easily, improve and erode efficiency and desilting effect.
Drawings
FIG. 1 is a schematic plan view of a portion of a sand dam of the present invention;
FIG. 2 is an elevational view of the sand dam of the present invention;
FIG. 3 is a sectional view of the sand trap of the present invention;
FIG. 4 is a schematic view of vertical connection of an overflow segment mortise and tenon structure;
FIG. 5 is a schematic view of a four configuration of prefabricated components;
FIG. 6 is a schematic illustration of the splicing of prefabricated components (including bolts);
FIG. 7 is a schematic illustration of the splicing of prefabricated components (without bolts);
in the figure, 1, a prefabricated part, 2, an anchor rod, 3, a apron, 4, an auxiliary dam, 5 and a steel plate.
Detailed Description
Examples
Taking the treatment of the mud-rock flow disasters of the green forest ditch as an example, the automatic dredging treatment is implemented on the ditch.
Chenjia dam village is a Wenchuan earthquake extremely serious disaster area, and develops a plurality of large-scale debris flow disasters, such as green forest ditches, Zhang Jia ditches, Yanjia ditches and the like. The green forest ditch is positioned at the right bank of the city dam river, and the catchment area of the drainage basin is 23.7km2The basin is in a pocket shape, the total length of a main channel is 6.8km, the relative height difference is 880m, the average longitudinal gradient is 142.3 per mill, and the average gradient is 6 degrees. The dam lake burst port breaks many times when encountering heavy rain in the later period, and induces many times of large-scale debris flow disasters: the total punching amount of 9.24 in 2008 is 80.5 multiplied by 104m3The total punching amount of '8.13' in 2010 reaches 160.5 multiplied by 104m3In 2013, the total yield of '7.9' in the year reaches 135.5 multiplied by 104m3. At present, the ditch is treated by adopting the traditional sand-blocking dam engineering, the reservoir area of the sand-blocking dam is full of silt, and in recent years, government departments invest a large amount of funds and manpower for later-stage maintenance work such as clearing the reservoir of the sand-blocking dam.
Aiming at the operation condition of the sand blocking dam of the green forest ditch, the detachable sand blocking dam for the debris flow, which can naturally desilt, is designed by taking the current survey design specification as the basis and combining with the characteristic parameters of debris flow disasters (the movement characteristic of the debris flow, the flow rate of the valley flood peak and the sand conveying capacity, the outburst frequency of the debris flow and the storage capacity of the sand blocking dam) and the engineering structure parameters (the height of the sand blocking dam, the stability of the sand blocking dam, the strength of the sand blocking dam and the size of an overflow port of the sand blocking dam).
The concrete structure is as follows: the upstream face of the main dam body is step-shaped, the slope of the upstream face dam body is 1:0.75, the back face is vertical, the width of the overflow section sand retaining dam is 60m, the depth of an overflow port is 2.5m, the total length of the pile structure is 4m, the width of the dam top is 2.0m, and the effective dam height is 12 m. The overflow section is divided into 3 parts by utilizing a pile structure, the length of each part is 20m, the height of each part is 12m, the pile structure is a cantilever pile, the pile depth is 24m, the embedded section is 12m, the cantilever end is 12m, and the cross section of the pile is 2.0m x 2.0 m. Each row of components on the vertical surface is arranged in a staggered mode as shown in figures 1-3. The structural size and the number of the overflow section dam body prefabricated parts are shown in the table 1, and the structures and the assembly forms of the prefabricated parts are shown in the figures 4-7.
TABLE 1 Overflow segment precast element size and quantity
During assembly, prestress 76KN is applied to the longitudinal anchor rods and the transverse anchor rods for reinforcing connection, then the sand blocking dam is adopted for carrying out sand blocking operation, and dredging operation is carried out after the reservoir area is filled with silt.
Before dredging operation, the maximum particle size and the scouring depth of natural scouring are firstly calculated according to sediment dynamics analysis, the proportion of deposits in a reservoir area which can be scoured away is calculated, and the dredging scale is determined. The maximum particle size of the sediment of the mud-rock flow in the green forest ditch is 0.5m, D900.27m, the minimum single-width clear water flow at the sand blocking dam is 2.5m3And/s, so that most of the silt in the reservoir area can be flushed.
And then, according to the determined dredging scale, disassembling a preset number of prefabricated parts at the top of the overflow section, wherein the disassembling height (H) is the dredging scale (V)/the area (S) of the reservoir area, during disassembling, unfastening the anchoring end of the anchor rod, taking off the integral anchor rod structure and the anti-impact steel plate on the top surface, disassembling the prefabricated parts with the designed disassembling height section, and applying a temporary reinforcing anchor rod at the disassembling section. The disassembly width is gradually reduced from top to bottom to form a V-shaped drainage port.
Then, a small excavator is used for excavating an overflow channel in a reservoir area, then, water flow is waited for rapidly flushing the reservoir area, after dredging is completed, the temporary anchor rod is detached, the prefabricated parts and the anti-scouring steel plate are reassembled, the prefabricated parts are arranged according to the surface damage degree, the prefabricated parts with serious surface damage are loaded on the middle lower part of the dam body, and the prefabricated parts with complete surfaces are loaded on the overflow surface of the sand blocking dam. If the prefabricated member is seriously damaged, a new member needs to be replaced in time.
In the natural dredging process, the reservoir area is cleaned only by disassembling and assembling the sand-blocking dam body, compared with the traditional dredging means, the workload of loading, transportation, abandoned slag stacking and the like in the dredging work is greatly reduced, a large amount of maintenance cost is saved, meanwhile, the structural strength of the sand-blocking dam body can be effectively controlled, and the service life of the sand-blocking dam is prolonged.
The design method is mature, simple in calculation, simple and easy in construction, small and mechanized, has very high practical value and economic value aiming at debris flow disasters with poor traffic conditions, high active period and large scale in mountainous areas, can be widely applied to treatment of various valley type extra-large debris flow disasters in mountainous areas, and particularly has strong suitability for treatment of debris flow disasters with the characteristics of large outburst scale, large blocking reservoir capacity and the like and strong main river silt transportation capacity.
Claims (6)
1. A naturally desilted debris flow sand dam is characterized by comprising a main dam body and an anti-scour auxiliary structure positioned on one side of the back surface of the main dam body, wherein the main dam body consists of non-overflow sections on the left side and the right side and an overflow section in the middle, the non-overflow sections are integrally formed in a concrete pouring mode, and the overflow section adopts a structure for assembling the dam body; the scour protection auxiliary structure is the combination of vice dam and apron, is equipped with the scour protection steel sheet that increases the whole scour protection ability of dam body at the upper surface of overflow section, the equipment dam body adopts mortise and tenon structure concatenation to form by the several prefabricated component, the prefabricated component includes cuboid form main part, is equipped with connecting portion in main part one side or both sides, be equipped with the anchor hole in the main part of prefabricated component, be equipped with the stock that the size matches in the anchor hole and connect the reinforcement to the equipment dam body, lay the sleeve pipe in the anchor hole, the stock passes through the grout and fixes in the sleeve pipe, and the bottom mounting of stock is structural in overflow section below, and the upper end is the anchor end.
2. The natural dredging debris flow sand dam of claim 1, wherein the upstream face of the main dam body is step-shaped, the slope of the upstream face dam body is 1:0.75-1:1, and the downstream face is vertical.
3. A natural dredging debris flow dam as claimed in claim 1, wherein the width of said overflow section is calculated and determined according to the debris flow and the valley condition, when the width is not more than 20m, only the structure of assembled dam body is adopted, and when the width is more than 20m, the structure of pile is adopted to separate the dam body of overflow section to strengthen the strength of assembled dam body.
4. The application of the naturally desilting debris flow dam of any one of claims 1 to 3 in desilting is characterized in that firstly, before desilting operation, the maximum particle size and the scouring depth of natural scouring are calculated according to silt dynamic analysis, and the proportion of deposits in a reservoir area which can be scoured away is calculated to determine the desilting scale; secondly, disassembling the prefabricated parts with the matched number of overflow sections according to the dredging scale, then excavating an overflow channel in the reservoir area, rapidly washing sediment in the reservoir area by utilizing concentrated water flow in the intermittent period of debris flow explosion for natural dredging, and reinstalling the disassembled prefabricated parts after dredging is completed to complete the dredging work of the sand dam.
5. The use of a naturally desilted debris flow dam in dredging as claimed in claim 4, wherein the dredging work is carried out in a sequential manner from upstream to downstream, and is carried out when the final dam is not full of the reservoir, with the final dam as a reserved safety reserve; before the prefabricated parts are disassembled, a groove is dug or a temporary diversion dike is built in the reservoir area, and the integral dredging speed of the reservoir area is accelerated in a water-restraining and sand-attacking mode.
6. The application of the naturally desilted debris flow dam of claim 5 in dredging, wherein when the assembled dam body is disassembled, the one-time disassembly height of the most downstream dam is controlled within the range of 0.1-0.2 times of the total dam height, the one-time disassembly height of the other dams is controlled within the range of 0.2-0.5 times of the effective dam height, and the section of the disassembled gap is designed to be V-shaped, so that the scouring of silt is accelerated; when the anchor rod is disassembled, the anchoring end of the anchor rod is unfastened, the prefabricated part is disassembled, the integral anchor rod structure is taken off, and temporary anchor rods are applied to two sides of the overflow section to form a V-shaped discharge port; after dredging is completed, the temporary anchor rods are disassembled, the prefabricated parts are reassembled according to the surface damage degree, the prefabricated parts with serious surface damage are loaded at the middle lower part, and the prefabricated parts with complete surfaces are loaded at the flow surface of the sand dam.
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| CN110055928B (en) * | 2019-04-28 | 2020-10-23 | 华北水利水电大学 | Method and system for repairing scoured riverbed at downstream of dam body |
| CN111639445B (en) * | 2020-06-19 | 2023-02-28 | 中国科学院、水利部成都山地灾害与环境研究所 | Method for measuring and calculating dangerousness of silt-returning accumulation body in front of debris flow dam in removal of retaining dam and application |
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| CN202298574U (en) * | 2008-10-26 | 2012-07-04 | 陈发明 | Spillover dam with water barrier |
| KR100918028B1 (en) * | 2009-03-19 | 2009-09-24 | 대한민국 | Sliding type concreen rhombic dam and construction method thereof |
| CN102535408B (en) * | 2012-02-10 | 2014-02-26 | 中国科学院水利部成都山地灾害与环境研究所 | Semi-assembly type ecological debris flow check dam, and construction method thereof |
| CN106498896B (en) * | 2016-09-06 | 2019-06-07 | 长江水利委员会长江科学院 | A kind of reservoir operation process analogy method being coupled with Sedimentation |
| CN206887895U (en) * | 2017-05-19 | 2018-01-16 | 兰州大学 | A kind of overflow-type mud-rock flow blocking dam group |
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Effective date of registration: 20221110 Address after: No.1, Section 2, North 1st ring road, Chengdu, Sichuan 610000 Patentee after: Chengdu Huajian Geological Engineering Technology Co.,Ltd. Address before: 611734 No.1, North 2nd section of 1st ring road, Jinniu District, Chengdu City, Sichuan Province Patentee before: INSTITUTE OF EXPLORATION TECHNOLOGY OF CHINESE ACADEMY OF GEOLOGICAL SCIENCES |
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