Composite blocking dam system with disaster prevention and control and ecological restoration functions

Abstract

The invention provides a composite blocking dam system with disaster prevention and control and ecological restoration functions, engineering construction is performed on a blocking dam by means of mountain valley terrain, and the blocking dam comprises a dam body, a foundation unit, an energy dissipation unit and a reinforcing unit; a plurality of concave overflow ports are formed in the middle of the top of the dam body and protrude forwards in the upstream direction. The foundation unit comprises a plurality of pile foundations, and the pile foundations are provided with transverse bearing platforms; the dam body is located on bearing platforms of the multiple pile foundations and attached to the pile foundations. The energy dissipation unit comprises a plurality of buffering reinforcing piles located behind the dam body, and the buffering reinforcing piles are located on the upstream of an overflow opening of the dam body and can receive impact of disasters before the overflow opening. The reinforcing unit comprises a plurality of anchor cables, and the anchor cables can reinforce the pile foundation and / or the buffer reinforcing piles. The composite type blocking dam system has the effects of improving the soil texture of loose accumulation bodies, treating debris flow / mountain torrent disasters, accumulating and fixing carbon and fixing soil and water.

Description

Technical Field

[0001] The present invention relates to the field of disaster prevention and control and ecological restoration. Specifically, it relates to a composite retaining dam system with functions of both disaster prevention and control and ecological restoration. Background Art

[0002] As an uncontrolled natural surface process, debris flow disasters have an adverse impact on human production and life, ecological environment, etc. during their occurrence and development. This destructive impact is mainly reflected in short-term effects. For example, during the movement of the debris flow disaster body, the debris flow destroys vegetation, farmland, and forests, resulting in landform damage and soil erosion; it also destroys the habitats of animals and plants, reduces biodiversity, blocks the food chain, and affects the regional ecological balance; at the same time, the destruction of vegetation leads to a decline in the carbon sequestration capacity and releases surface greenhouse gases. Moreover, debris flow has a direct or indirect adverse impact on hydrological safety and human activities. However, from the long-term activities of debris flow, as a natural surface geological activity phenomenon in nature, debris flow has the role of promoting landform renewal, promoting material circulation, and providing a new living environment for organisms. Therefore, from the perspective of the process of material flow and energy release, reducing the short-term adverse effects of debris flow disasters and promoting the long-term beneficial effects on the ecological environment and human activities are the fundamental purposes of comprehensive disaster management.

[0003] The present invention aims to provide a composite retaining dam with functions of both disaster prevention and control and ecological restoration. Through the synergistic effect of engineering structures and ecological means, it reduces the short-term hazards of debris flow, and at the same time uses the organic matter and minerals carried by it to construct eutrophic soil, forming a sustainable ecological-engineering system. Summary of the Invention

[0004] The purpose of the present invention is to solve at least one of the above-mentioned deficiencies existing in the prior art. For example, one of the purposes of the present invention is to provide a composite retaining dam with functions of both disaster prevention and control and ecological restoration; the second purpose of the present invention is to provide a composite retaining dam system with functions of both disaster prevention and control and ecological restoration.

[0005] To achieve the above purpose, on the one hand, the present invention provides a composite retaining dam project with functions of both disaster prevention and control and ecological restoration. The retaining dam is constructed by means of the mountain valley terrain. The retaining dam includes a dam body, a foundation unit, an energy dissipation unit, and a reinforcement unit;

[0006] In the middle of the top of the dam body, there are several concave overflow openings, and the overflow openings protrude forward in the upstream direction;

[0007] The foundation unit includes a plurality of pile foundations, and the pile foundations have transverse bearing platforms;

[0008] The dam body is located on the bearing platforms of the plurality of pile foundations and fits with the pile foundations;

[0009] The energy dissipation unit includes a number of buffer reinforcement piles, which are located upstream of the overflow opening of the dam body and can receive the impact of disasters prior to the overflow opening.

[0010] The reinforcement unit includes a plurality of anchor cables. The outer end of the anchor cable is fixed to the pile foundation, and the middle part passes through and is fixed to the buffer reinforcement pile. The anchor cable can reinforce the pile foundation and / or the buffer reinforcement pile.

[0011] Optionally, the dam body is a gabion dam body, which is integrally in a folded line shape, and the lower part of the dam body is located below the ground surface.

[0012] Optionally, the lower section of the pile foundation is located below the ground surface, and the bearing platform is vertically arranged on the lower section.

[0013] Optionally, one end of the anchor cable is fixed below the ground surface upstream of the dam body.

[0014] Optionally, the other end of the anchor cable passes through the buffer reinforcement pile body and is fixed.

[0015] On the other hand, the present invention provides a composite retaining system with both disaster prevention and control and ecological restoration functions. The system includes: a multi-level composite retaining dam arranged successively from bottom to top along the mountain valley terrain. The retaining dam is the above-mentioned retaining dam, wherein the structural dimensions and quantities of the retaining dams are determined according to requirements.

[0016] The system further includes: functional flora and plant communities.

[0017] Optionally, the construction steps of the system include:

[0018] Excavating, compacting and deep grouting the accumulation body of the foundation ground to increase the bearing capacity of the ground to ≥120 kPa; excavating the foundation pit, constructing the pile foundation and the buffer reinforcement pile, and carrying out the construction of the anchor cable project; laying geogrid on the foundation base and connecting it with the bearing platform surface of the pile foundation as a reinforced layer; constructing the gabion dam body;

[0019] Setting a stepped diversion channel between the upper and lower dam bodies; setting an interlocking gabion structure at the lateral extension part of the adjacent dam bodies, with an overlapping length ≥2 m; extending the dam body into the slope bodies on both sides;

[0020] After each level of the dam body is constructed, spraying plant seeds and microbial agents on the sediment surface, with a coverage rate ≥80%; pre-burying plant growth substrate packages containing slow-release fertilizers and water-retaining agents in the pores of the dam body, with a buried depth of 20 - 40 cm.

[0021] Optionally, the compactness of the compaction ≥85%; the slurry for the deep grouting includes cement-fly ash slurry, and the grouting pressure is 0.3 - 0.5 MPa. The tensile strength of the geogrid laid on the foundation base ≥50 kN / m.

[0022] Optionally, the number of levels of the multi - level composite retaining dam is determined by the height of the sediment accumulation behind the dam body. When the height of the sediment accumulation behind a certain level of the dam body reaches 90% - 95% of the designed top elevation of this level of the dam body, the construction process of the next level of the dam body is carried out.

[0023] Optionally, the spacing between the dam bodies of the multi - level composite retaining dam is determined by the engineering situation. Among them, the spacing range of the dam bodies includes where \(h_0\) is the height of a single - level dam body above the ground, and \(\theta_0\) is the inclination angle of the debris - flow gully bottom where the single - level dam body is located; the single - body height and multi - level structure of the dam body need to meet the long - term stability under full load.

[0024] Optionally, the functional flora and plant community are developed by spraying plant seeds and microbial agents;

[0025] The plant community includes aquatic plants and terrestrial plants. The aquatic plants include emergent plants, floating and submerged plants. The emergent plants include reed or cattail, and the floating and submerged plants include duckweed and vallisneria; the terrestrial plants are planted in a phased gradient, and a succession system of "pioneer herbs - stress - tolerant shrubs - stable arbors" is designed. The pioneer herb layer includes miscanthus or alfalfa, the stress - tolerant shrubs include seabuckthorn or coriaria nepalensis, and the stable arbors include alnus cremastogyne or Chinese fir;

[0026] The functional flora includes organic matter decomposing bacteria, nitrogen - fixing and phosphorus - solubilizing bacteria, and heavy - metal passivating bacteria. The organic matter decomposing bacteria include cold - tolerant actinomycetes, the nitrogen - fixing and phosphorus - solubilizing bacteria include native rhizobia and phosphorus - solubilizing pseudomonas, and the heavy - metal passivating bacteria include sulfur - oxidizing bacteria and phosphate - dissolving bacteria.

[0027] Optionally, the system also includes establishing various parameter monitoring, and the monitoring includes monitoring of debris - flow impact force, soil physical and chemical indexes, and ecological indexes.

[0028] Optionally, the system has the functions of disaster prevention and control and ecological restoration. The disaster prevention and control includes improving the soil quality of loose accumulations and controlling debris - flow / mountain - flood disasters; the ecological restoration includes the function of gradually accumulating carbon sequestration and the function of plant roots in stabilizing soil and conserving water.

[0029] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0030] (1) Through the design of multi - level frontal - impact - energy - dissipating gabion dam bodies, the present invention has both the functions of energy dissipation and interception and pore water permeability. The design of buffer reinforcement piles combined with the dam body structure forms a double protection of "pile - group energy dissipation - dam body interception", achieving an effect of "one plus one is greater than two".

[0031] (2) The present invention establishes an ecological-engineering coupling model, which transforms the disaster body into an ecological matrix through material interception and humification, thus realizing "using disasters to support ecology". A step-by-step trigger construction is adopted, that is, the construction of the next level of dam body is dynamically started according to the accumulated height of sediments (reaching 90%-95% of the dam top), and the previous level of sediments is used as the foundation of the next level to reduce construction costs. An ecological synchronous restoration process is adopted. After each level of the dam body is completed, native grass seeds and fungal agents are sprayed immediately, and plant growth substrate packages (including slow-release fertilizers) are pre-buried to accelerate the formation of the ecological matrix. In summary, the present invention organically combines engineering and ecology, conforms to the "mountains, rivers, forests, fields, lakes and grasses" system governance concept, and has broad application prospects in the prevention and control of debris flows in mountainous areas.

[0032] (3) The present invention has lower construction costs and maintenance costs than traditional concrete dams, and can also promote ecological and economic development, with high benefits. The present invention utilizes organic matter and minerals in debris flow sediments and transforms them into fertile soil, realizing a sustainable management model of "using disasters to support ecology" and recycling resources. The present invention can accumulate carbon sinks, with the annual carbon fixation of vegetation and microorganisms reaching 4.2t / ha, and the carbon storage within a 10-year period increased to 3 times the baseline level. In summary, the present invention has the characteristics of economic benefits and sustainability.

[0033] (4) The retaining dam system of the present invention can bring comprehensive benefits that are adapted to local conditions, including: Ecological benefits: The annual water purification volume of the aquatic system is 80,000 to 120,000 m 3 , the terrestrial vegetation coverage rate reached 70% to 85% in 3 years, attracting local birds (such as egrets and kingfishers) and insect communities to rebuild; engineering stability: plant roots and microorganisms work together to consolidate sediments, and the dam's anti-slip coefficient is increased to above 1.5; root reinforcement: plant roots reinforce the land, which can retain water and soil and reduce the harm of disasters; economic and social benefits: the utilization of native plants and biological resources reduces maintenance costs. For example, harvesting aquatic plants (such as reeds) can be used for weaving or biomass energy, with an annual output value of 150-200 yuan / mu. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above and other objects and / or features of the present invention will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0035] Figure 1 A top plan view and an energy dissipation schematic diagram of the retaining dam body of the present invention are shown.

[0036] Figure 2 A schematic diagram of a composite retaining dam model having both disaster prevention and control and ecological restoration functions according to the present invention is shown.

[0037] Figure 3 The main structural schematic diagram of a single-stage dam body in the multi-stage composite retaining dam of the present invention is shown.

[0038] Figure 4 Shows the main structure plan of a single-stage dam in the multi-stage composite retaining dam of the present invention.

[0039] Figure 5 Shows the elevation view of a single-stage dam in the multi-stage composite retaining dam of the present invention.

[0040] Figure 6 Shows the side elevation of a single-stage dam in the multi-stage composite retaining dam of the present invention.

[0041] Figure 7 Shows the plan view of the composite retaining dam with both disaster prevention and control and ecological restoration functions of the present invention.

[0042] Figure 8 Shows Figure 7 The cross-sectional view at 1-1 in

[0043] Figure 9 Shows Figure 7 The cross-sectional view at 2-2 in

[0044] Description of main reference numerals:

[0045] a - Pile foundation; b - Anchor cable; c - Anchor head; d - Buffer reinforcement pile; e - Dam body;

[0046] A - Overflow opening; B - Multi-stage dam; C - Artificial lake; D1 - Inter-dam accumulation body; D2 - Post-dam accumulation body; E - Valley slope; F - Gully slope bottom; G - Decompose impact force; H - Dam body windward surface; I - Vortex energy dissipation; J - Eliminate part of the impact; K - Flash flood & debris flow; L - Slow flow during non-disaster period; M - Multi-stage accumulation layer line. Detailed implementation manners

[0047] In the following, a composite retaining dam system with both disaster prevention and control and ecological restoration functions of the present invention will be described in detail with reference to exemplary embodiments.

[0048] It should be noted that "first", "second", "third", "fourth", etc. are only for convenience of description and easy distinction, and cannot be understood as indicating or implying relative importance. "Up", "down", "front", "back", "left", "right", "inside", "outside", etc. are only for convenience of description and to form a relative orientation or positional relationship, and do not indicate or imply that the referred components must have that specific orientation or position.

[0049] Exemplary embodiment 1

[0050] This exemplary embodiment provides a composite retaining dam project with both disaster prevention and control and ecological restoration functions. The retaining dam is constructed by leveraging the terrain of mountain valleys. The retaining dam may include a dam body e, a foundation unit, an energy dissipation unit, and a reinforcement unit;

[0051] In the middle of the top of the dam body e, there are several concave overflow openings A, and the overflow opening A protrudes forward in the upstream direction;

[0052] The foundation unit includes multiple pile foundations a, and the pile foundations a have horizontal bearing platforms;

[0053] The dam body e is located on the bearing platforms of the multiple pile foundations a and fits with the pile foundations a;

[0054] The energy dissipation unit includes several buffer reinforcement piles d located behind the dam body e. The buffer reinforcement piles d are located upstream of the overflow opening A of the dam body e and can receive the impact of disasters prior to the overflow opening A;

[0055] The reinforcement unit includes multiple anchor cables b. The outer ends of the anchor cables b are fixed to the pile foundations a, and the middle parts pass through the buffer reinforcement piles d and are fixed to the buffer reinforcement piles d. The anchor cables b can reinforce the pile foundations a and / or the buffer reinforcement piles d.

[0056] In this embodiment, as Figure 3 shown, the buffer reinforcement piles d can also prevent boulders from damaging the gabion to protect the safety of the dam body e, and the buffer reinforcement piles d can also provide a certain amount of tensile resistance to the anchor cables b (with anchor heads c), playing a role in multiple reinforcement and stability; in addition, in principle, the height of the buffer reinforcement piles d is such that the top of the pile is not lower than the overflow opening A and not higher than the dam body e.

[0057] Among them, the buffer reinforcement piles d can significantly improve the stability and tensile resistance of the anchor cables b. This design takes into account the complex and harsh conditions of the upstream direction of the dam body overflow opening A, which is affected by various effects such as the impact, erosion, and slow flow of disaster bodies, and is set to improve the effectiveness and stability of the structure.

[0058] In this embodiment, the dam body e is a gabion dam body, which is integrally zigzag. The lower part of the dam body is located below the ground surface. The height of the gabion dam body is 3 - 5 m above the ground surface and 0.5 - 1.5 m below the ground surface. The length is determined according to the width of the trench, and the gabion thickness is 1 - 3 m.

[0059] Among them, the gabion dam body is composed of multiple multi-layered gabion cages, which are connected and combined by reinforcing materials. The cross-sectional shape of the dam body can be any suitable shape such as a rectangle or a trapezoid. The filling materials of the cages include galvanized high-tensile steel wire gabions (service life ≥ 50 years), the filled stones include angular stones, and the gradation of the filling materials satisfies D50 = 20 - 40 cm, Cu = 2.0 - 4.0, Cc = 2.0 - 3.0; that is, it meets the water permeability under the initial conditions of the structure (the porosity remains 30 - 40% in the initial stage and is naturally adjusted by deposits, biological actions, and vegetation roots in the later stage), and when the gabion is subjected to a great impact force from an external disaster body, it can undergo limited deformation, enabling the stones to dissipate energy through friction and ensuring the overall stability of the structure. When the gradation of the filling materials and the size parameters of the gabion wall are uncertain, they can be determined through water permeability tests and impact tests.

[0060] In this embodiment, the overflow port A includes a first horizontal section, a first inclined section, a second horizontal section, a second inclined section, and a third horizontal section connected in sequence. Among them, the first and third horizontal sections are parallel, the second and third horizontal sections are parallel, the included angle between the first inclined section and the third horizontal section is an obtuse angle, the included angle between the second inclined section and the third horizontal section is an obtuse angle, or in other words, the length of the second horizontal section is less than the distance between the first and third horizontal sections.

[0061] In this embodiment, the lower section of the pile foundation a is located below the ground surface, and the bearing platform is vertically arranged below the lower section.

[0062] Among them, the pile foundation a mainly provides anti-overturning moment, shear resistance, and partial foundation bearing capacity for the gabion dam body e. The gabion is located on the top surface of the bearing platform and is in contact with the pile foundation a. The pile foundation a is reinforced by at least two anchor cables b. Among them, there is a locking anchor cable at the lower part of the bearing platform to increase the anti-sliding force of the pile foundation a, and the upper anchor cables b provide tensile resistance for the pile foundation a, optimizing the force on the pile body and improving the anti-overturning and anti-shearing capabilities of the dam body.

[0063] In this embodiment, one end of the anchor cable b is fixed below the ground surface upstream of the dam body e.

[0064] In this embodiment, the other end of the anchor cable b passes through the buffer reinforcement pile d and is fixed.

[0065] In this embodiment, by constructing a composite retaining dam project with both disaster prevention and control and ecological restoration functions, the following action mechanisms can be brought:

[0066] (1) Treatment of debris flow / hill flood disasters. When the hill flood & debris flow K moves in the flow area, water and solid rock and soil materials, mixed with the remains of animals and plants, flow downward. The gabion dam body itself has the function of blocking and resolving the impact of debris flow and separating water and stones (porous medium). For example Figure 1As shown in the figure, the plan view of a single retaining dam with a composite structure of gabion retaining wall-pile-anchor first meets the impact of debris flow through the energy dissipation piles behind the dam, eliminating part of the impact J; then the dam body's face H receives the impact, and the overflow port A in the middle of the face is convex to the upstream, and the inclined surface can decompose the impact force G and guide the fluid to move to both sides. The fluid guided by the dam body to flow to both sides forms a vortex under the constraints of the dam body and the two banks on both sides. The vortex itself consumes kinetic energy, that is, vortex energy dissipation I, and dissolves the impact force of the debris flow directly rushing to the dam body on both sides. The gabion dam itself is a porous medium that can intercept solids, analyze the effects of slurry and large particles, and thus achieve water-rock separation. In addition, consistent with traditional debris flow retaining dams, the "concave" overflow port in the middle of the dam body can overflow the excess debris flow and protect the dam body itself.

[0067] (2) Control of rock, soil and other materials. As mentioned above, the gabion dam will intercept some of the solid matter in the debris flow, including coarse particles such as stones and sand, as well as tree branches, animal and plant debris, etc. These materials will be deposited behind the dam. At the same time, the solid particles will gradually block the larger pores in the gabions and reduce the permeability of the dam body, which will help to accumulate and enrich the debris flow slurry and tiny particles in the normal flow water and various nutrients such as minerals dissolved from rocks behind the dam body. Through the construction of multiple dams B in succession, between the dam bodies and behind the dams, the inter-dam accumulation body D1 and the post-dam accumulation body D2 are formed. E is the valley slope, and L is the slow flow in the non-disaster period. Figure 2 shown.

[0068] (3) Water control. The water in the disaster body and the long-term slow-flowing water are blocked by the barrier dam and gathered in a certain area behind the dam to form an artificial lake C. The lake is interconnected with the groundwater in the surrounding rock and soil, improving the regional water level circulation and regulation. In addition, the evaporation of the catchment area can also affect the local humidity for a long time, forming a suitable ecological environment.

[0069] (4) Construction of ecological living space. 1) After the porous dam is constructed, the solids in the dam are connected to the air and water, creating a living space for microorganisms, small animals and plants. 2) The water collection area behind the dam top (artificial lake C) provides an aquatic ecological environment, providing space for aquatic plants and animals and microorganisms. 3) The exposed land behind the dam has good nutrient conditions and abundant water resources, forming a good water-land ecological environment. Therefore, as the multi-level dam rises, the accumulation of materials and the expansion of enrichment space around the dam form a good local water-land ecological environment.

[0070] Exemplary Embodiment 2

[0071] Another aspect of the present invention provides a composite barrier system with both disaster prevention and control and ecological restoration functions, the system comprising: a multi-stage composite barrier dam arranged from bottom to top along the mountain valley terrain, the barrier dam being the barrier dam described in exemplary embodiment 1, wherein the structural size and number of the barrier dam are determined according to demand;

[0072] The system also includes: functional bacterial communities and plant communities.

[0073] In this embodiment, the steps of constructing the system include:

[0074] Excavate, compact and deep grout the accumulation of the foundation to increase the foundation bearing capacity to ≥120kPa; excavate the foundation pit, build pile foundation a and buffer reinforcement pile d, and carry out anchor cable b construction; lay geogrids on the base and connect them to the pile foundation bearing platform as a reinforcement layer; build the gabion dam body;

[0075] A stepped diversion channel is set between the upper and lower dam bodies; an interlocking gabion structure is set on the lateral extension of the adjacent dam bodies, with an overlapping length of ≥ 2m; the dam body extends to the inside of the slopes on both sides;

[0076] After each level of the dam is constructed, plant seeds and microbial agents are sprayed on the sediment surface with a coverage rate of ≥80%; plant growth substrate bags containing slow-release fertilizers and water-retaining agents are pre-buried in the pores of the dam body with a burial depth of 20 to 40 cm.

[0077] In this embodiment, the compaction degree of the compaction is ≥85%; the slurry for the deep grouting includes cement-fly ash slurry, the grouting pressure is 0.3-0.5 MPa, and the tensile strength of the geogrid laid on the substrate is ≥50 kN / m.

[0078] In this embodiment, the number of stages of the multi-stage composite retaining dam is determined by the height of sediment accumulation behind the dam body. When the height of sediment accumulation behind a certain stage of the dam body reaches 90% to 95% of the designed top elevation of the dam body at that stage, the construction procedure of the next stage of the dam body is carried out.

[0079] In this embodiment, the spacing between the dam bodies of the multi-stage composite retaining dam is determined by the engineering conditions, wherein the spacing range of the dam bodies includes h0 is the height of the single-stage dam body above the ground, θ0 is the inclination angle of the debris flow ditch bottom at the location of the single-stage dam body; the single-unit height and multi-stage structure of the dam body must meet the long-term stability when fully loaded.

[0080] In addition, the height of the multi-level dam is mainly based on the area of the accumulation body behind the dam to meet the needs of an open ecosystem for space, material, and energy input; considering the long-term safety of the geological environment, part of the soil and water should be retained. After the geological active period and until long-term geological disasters are safe and stable, the total solid materials retained should not exceed 5% of the total solid materials transported downstream (i.e., while controlling the utilization of the disaster process, the natural geological processes on the earth's surface are not reversed).

[0081] The main structure plan view, three-dimensional view, and side elevation view of a single-level dam body are respectively as Figure 4 , Figure 5 and Figure 6 shown. For each level of the dam body, the dam body at the overflow port A bulges upstream, that is, it receives the impact of debris flow (and mountain flood) earlier than the main gabion dam body. This design is obviously for the purpose of accelerating drainage, decomposing the impact force G, and creating vortices by diversion. Figure 4 The dam body shown has an overflow port A on the plane, bulges upstream, and the plane of the dam body is zigzag. Obviously, multiple overflow ports and other curve shapes suitable for the terrain and functions are also applicable.

[0082] In this embodiment, the composite retaining system with both disaster prevention and control and ecological restoration functions is as Figure 7 , Figure 8 and Figure 9 shown, where F is the bottom of the valley slope and M is the multi-level accumulation layer line.

[0083] In this embodiment, the functional flora and plant community are developed by spraying plant seeds and microbial inoculants;

[0084] The plant community includes aquatic plants and terrestrial plants. The aquatic plants include emergent plants, floating and submerged plants. The emergent plants include reeds or cattails, and the floating and submerged plants include duckweed and vallisneria; the terrestrial plants are planted in a phased gradient, and a succession system of "pioneer herbs - stress-tolerant shrubs - stable trees" is designed. The pioneer herb layer includes Chinese silvergrass or alfalfa, the stress-tolerant shrubs include sea buckthorn or coriaria nepalensis, and the stable trees include alnus cremastogyne or Chinese fir;

[0085] The functional flora includes organic matter decomposing bacteria, nitrogen-fixing and phosphorus-solubilizing bacteria, and heavy metal passivating bacteria. The organic matter decomposing bacteria include cold-tolerant actinomycetes, the nitrogen-fixing and phosphorus-solubilizing bacteria include native rhizobia and phosphorus-solubilizing pseudomonas, and the heavy metal passivating bacteria include sulfur-oxidizing bacteria and phosphate-dissolving bacteria.

[0086] In this embodiment, the system also includes establishing multiple parameter monitors, and the monitors include debris flow impact force, soil physical and chemical indexes, and ecological index monitors.

[0087] In this embodiment, the system has the functions of disaster prevention and control and ecological restoration. The disaster prevention and control includes improving the soil quality of loose accumulations and controlling debris flow / hill flood disasters; the ecological restoration includes the function of gradually accumulating carbon sequestration and the function of soil and water conservation by plant roots.

[0088] By constructing a composite retaining system with both disaster prevention and control and ecological restoration functions, the following mechanism of action will be generated in the ecological environment:

[0089] (1) Improve the soil quality of loose accumulations. For the accumulation body D2 behind the dam, it is mainly composed of weathered products of rock masses in the upstream mountain carried by debris flow and various-sized loose debris formed by collapses and landslides, which are stacked layer by layer from bottom to top. During the fragmentation process of the rock masses in the upstream mountain, substances in the deep rocks are exposed on the surface. Under the action of surface runoff, some substances are dissolved in water, including inorganic trace elements such as Ka, Ca, and Fe. These essential nutrient elements for plants and some microorganisms are partially filtered and retained in the accumulation body D2 behind the dam along with the constant slow flow or flood during the disaster period. In addition, the remains of animals and plants carried by the debris flow and the remains of animals and plants growing on the accumulation body D2 behind the dam are partially intercepted and buried in the soil behind the dam, forming fertile land through humification. In addition, functional microbial communities (such as nitrogen-fixing bacteria and phosphate-solubilizing bacteria) can be implanted into the pores of the dam body to form a synergistic purification system with plants such as reeds.

[0090] (2) Gradually accumulate carbon sequestration. As the multi-level dam body rises, the remains of animals and plants gradually accumulate layer by layer in the accumulation body behind the dam, and the biomass of terrestrial vegetation, aquatic plants, etc. on the accumulation body D2 behind the dam gradually increases. Due to the fertile land and abundant water sources, the surface vegetation fixes CO2 through photosynthesis and forms a carbon pool after long-term accumulation.

[0091] The function of surface vegetation in soil and water conservation. On the fertile land formed by the accumulation between the dam body and the top of the dam, in addition to natural wild plants, drought-tolerant and flood-tolerant plants (such as reeds and sea buckthorn) can also be sown. In addition to accelerating carbon sequestration, the roots reinforce the accumulation body and reduce soil erosion.

[0092] Based on the above mechanism of action, in the case of long-term input of matter and energy, the following ecological benefits will be brought:

[0093] (1) Water resources. After a multi-level good ecological system is formed among microorganisms, animals and plants, and the living environment, the water quality and quantity of the artificial lake behind the dam will gradually increase, becoming a good water source for agricultural use. At this time, water intake facilities can be constructed in the artificial lake and, with the help of the terrain, it can become a low-energy water source for downstream agricultural planting.

[0094] (2) Land resources. After the large-scale accumulations between and behind the dams form fertile land, local wild animals, plants, and microorganisms will multiply in large numbers. While improving the soil quality, they fix the soil and retain water. With the evolution of the ecosystem, it gradually develops into high-quality forest land. With the input of matter and energy, a dynamically stable ecosystem is ultimately formed. When the frequency of disasters in this basin decreases to a low-risk area, the land can be used as economic forest land, and thus biological resources can be obtained.

[0095] Landscape resources. In summary, after the watershed-type mountain torrents and debris flows in this mountainous area are gradually controlled, the increasingly abundant ecological chain, rich vegetation, and the surrounding environment form a "mountain-water-forest" landform. Coupled with the original ecological and low-pollution natural conditions in the mountainous area, it is inevitable to form landscape resources with economic value.

[0096] Although the present invention has been described above in connection with exemplary embodiments and the accompanying drawings, those of ordinary skill in the art should understand that various modifications can be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A composite retaining dam with both disaster prevention and control and ecological restoration functions, characterized in that, The retaining dam is constructed by taking advantage of the mountain valley terrain, and the retaining dam includes a dam body, a foundation unit, an energy dissipation unit and a reinforcement unit; There are several concave overflow ports in the middle of the top of the dam body, which are convex toward the upstream direction; The foundation unit includes a plurality of pile foundations, and the pile foundations have transverse caps; The dam body is located on the cap of the plurality of pile foundations and fits the pile foundations; The energy dissipation unit includes a number of buffer reinforcement piles, which are located upstream of the overflow outlet of the dam body and can receive the impact of disasters before the overflow outlet; The reinforcement unit includes a plurality of anchor cables, the outer ends of the anchor cables are fixed to the pile foundation, the middle parts pass through the buffer reinforcement piles and are fixed to the buffer reinforcement piles, and the anchor cables can reinforce the pile foundation and / or the buffer reinforcement piles.

2. The composite retaining dam with both disaster prevention and control and ecological restoration functions according to claim 1, wherein, The dam body is a gabion dam body, which is in a broken line shape as a whole, and the lower part of the dam body is located below the ground surface; the lower section of the pile foundation is located below the ground surface, and the cap is vertically arranged in the lower section.

3. The composite retaining dam with both disaster prevention and control and ecological restoration functions according to claim 1, characterized in that One end of the anchor cable is fixed below the ground surface upstream of the dam body, and the other end of the anchor cable passes through the buffer reinforcement pile body and is fixed.

4. A composite retaining dam system with both disaster prevention and control and ecological restoration functions, characterized in that, The system comprises: a multi-stage composite retaining dam arranged in sequence from bottom to top along the mountain valley terrain, wherein the retaining dam is the retaining dam according to any one of claims 1 to 3, wherein the structural size and number of the retaining dam are determined according to demand; The system also includes: functional bacterial communities and plant communities.

5. The composite retaining dam system with disaster prevention and control and ecological restoration functions according to claim 4, characterized in that, The steps of building the system include: Excavate, compact and deep grout the accumulation of the foundation to increase the foundation bearing capacity to ≥120kPa; excavate the foundation pit, build pile foundations and buffer reinforcement piles, and carry out anchor cable construction; lay geogrids on the base and connect them to the pile foundation bearing platform as a reinforcement layer; build the gabion dam body; A stepped diversion channel is set between the upper and lower dam bodies; an interlocking gabion structure is set on the lateral extension of the adjacent dam bodies, with an overlapping length of ≥ 2m; the dam body extends to the inside of the slopes on both sides; After each level of the dam is constructed, plant seeds and microbial agents are sprayed on the sediment surface with a coverage rate of ≥80%; plant growth substrate bags containing slow-release fertilizers and water-retaining agents are pre-buried in the pores of the dam body with a burial depth of 20 to 40 cm.

6. The composite retaining dam system with disaster prevention and control and ecological restoration functions according to claim 5, characterized in that, The compaction degree of the compaction is ≥85%; the slurry for the deep grouting includes cement-fly ash slurry, the grouting pressure is 0.3-0.5MPa, and the tensile strength of the geogrid laid on the substrate is ≥50kN / m.

7. The composite retaining dam system with disaster prevention and control and ecological restoration functions according to claim 5, characterized in that, The number of stages of the multi-stage composite retaining dam is determined by the height of sediment accumulation behind the dam body. When the height of sediment accumulation behind a certain stage of the dam body reaches 90% to 95% of the designed top elevation of the dam body at that stage, the construction procedure of the next stage of the dam body is carried out; The spacing between the dam bodies of the multi-level composite retaining dam is determined by the engineering conditions. Among them, the spacing range of the dam bodies includes h0 is the height of a single-stage dam body above the ground surface, and θ0 is the inclination angle of the debris flow gully bottom where the single-stage dam body is located; the single-body height and multi-level structure of the dam body need to meet the long-term stability under full load.

8. The composite retaining dam system with disaster prevention and control and ecological restoration functions according to claim 5, characterized in that, The functional bacterial community and plant community are developed by spraying plant seeds and microbial agents; The plant community includes aquatic plants and terrestrial plants. The aquatic plants include emergent plants, floating plants and submerged plants. The emergent plants include reeds or cattails, and the floating plants and submerged plants include duckweed and Vallisneria. The terrestrial plants are planted in stages and gradients, and a "pioneer herb-resistant shrub-stable tree" succession system is designed. The pioneer herb layer includes Miscanthus or alfalfa, the stress-resistant shrubs include seabuckthorn or Coriaria, and the stable trees include Alnus or Cunninghamia lanceolata. The functional flora includes organic matter decomposing bacteria, nitrogen-fixing and phosphorus-solubilizing bacteria, and heavy metal passivating bacteria. The organic matter decomposing bacteria include cold-resistant actinomycetes. The nitrogen-fixing and phosphorus-solubilizing bacteria include native rhizobia and phosphorus-solubilizing Pseudomonas. The heavy metal passivating bacteria include sulfur-oxidizing bacteria and phosphate-solubilizing bacteria.

9. The composite retaining dam system with both disaster prevention and control and ecological restoration functions according to claim 5, characterized in that, The system also includes the establishment of various parameter monitoring, and the monitoring includes debris flow impact force, soil physical and chemical index, and ecological index monitoring.

10. The composite retaining dam system with both disaster prevention and control and ecological restoration functions according to claim 5, characterized in that, The system has the functions of disaster prevention and control and ecological restoration. The disaster prevention and control includes improving the soil quality of loose accumulation bodies and controlling debris flow / flood disasters. The ecological restoration includes the function of gradually accumulating carbon fixation and the function of soil and water conservation by plant roots.

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