River and beach surface soil body exhausting and danger removing device and method

Abstract

The invention provides an exhausting and danger removing device and method for river and beach surface soil. The device comprises an exhausting solid pipe section and an exhausting floral pipe section which are connected with each other. The bottom of the exhaust solid pipe section is buried in a river beach weak permeable soil layer, the top end is provided with a top sealing plate for preventing rainwater from entering, and the top side is provided with a horizontal exhaust hole higher than the designed flood level for exhausting; the top of the exhaust floral pipe section is connected with the bottom of the exhaust solid pipe section, the periphery of the exhaust floral pipe section is wrapped with nylon gauze and filled with inverted filter sand to form an inverted filter system to prevent sand from entering, and the bottom of the exhaust floral pipe section is provided with a bottom sealing plate to prevent soil particles from entering the pipe and ensure that gas is collected and exhausted. When the water level of a rainstorm river suddenly rises to form gas sealing after long-term drought, pressure gas generated by'water-gas displacement 'of a sandy gravel stratum can be discharged, 'cavitation' damage of a surface soil body of an embankment beach land is prevented, the anti-seepage function of an aquitard is protected, and the flood prevention safety of the embankment in the flood season is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of flood control and disaster reduction in water conservancy and dikes, specifically to a device and method for venting and eliminating hazards in the surface soil of river beaches. Background Technology

[0002] The foundations of the dikes in the Yangtze River basin are mostly composed of a surface layer of poorly permeable clay or silty clay, underlain by a layer of highly permeable sand or gravel. This is a geological reason why piping is prone to occur under high water levels during the flood season in the Yangtze River basin. In addition, the geological structure of the river floodplains in the Yangtze River basin is also basically this type of stratum. For example, the floodplains in the middle and lower reaches of the Xiang, Zi, Yuan, and Li rivers, tributaries of Dongting Lake, have obvious dual-structure characteristics, with a thin surface layer of poorly permeable soil and a thick layer of gravel underneath.

[0003] Due to climate influences, the Yangtze River basin experiences a dry season in winter with low river levels, while summer sees higher water levels, marking the flood season. In certain exceptional years, such as prolonged droughts and persistently low river levels, a sudden torrential downpour in early summer can cause a sharp rise in river levels, even overflowing the riverbanks. During this process, a large amount of gas in the vadose zone of the sand and gravel layer beneath the riverbanks, formed by the prolonged drought, cannot be released in time. Furthermore, the surface soil of the riverbanks becomes saturated with rainfall and rising water, forming a sealed layer. Over time, the infiltration of river water causes the groundwater infiltration line to continuously rise, displacing the gas within the vadose zone of the sand and gravel layer. Under these conditions, the resulting pressurized gas breaks through the surface soil of the riverbanks, escaping at weak points and creating a large amount of continuous bubbling in the shallow water above the riverbank surface. Essentially, the sealed conditions created by the sudden rise in river water, coupled with the groundwater infiltration line over time, lead to a physical phenomenon of water-gas displacement. This compression of the gas within the vadose zone of the sand and gravel layer causes "gas erosion" damage at weak points in the surface soil of the riverbanks. Although this phenomenon is caused by meteorological drought combined with sudden rainfall, it is difficult to avoid in the long run. Once it occurs, the surface soil of the dike and riverbank may be damaged by "aerosol erosion", which will damage the seepage prevention function of the surface soil, shorten the seepage path of the dike, and make the inner side of the dike more prone to piping damage, seriously threatening the flood control safety of the dike.

[0004] Currently, both domestically and internationally, the usual methods for managing dike hazards involve laying clay horizontally on the back side of the dike or installing self-draining drainage wells to prevent piping. Dike reinforcement typically employs methods such as seepage-proof walls or cone grouting. For riverbank slopes, various types of riprap revetments or concrete protection are commonly used to prevent erosion or instability. However, there is no understanding or management measures for gas damage in the riverbank strata.

[0005] Given this specific context, this invention addresses the risk of surface soil damage during water-air displacement processes in riverbanks by designing a special device, thereby eliminating potential safety hazards to dikes. This method fills a gap in the industry. Summary of the Invention

[0006] This invention provides a device and method for venting and eliminating hazards in the surface soil of riverbanks, which solves the problem of damage to the surface soil of riverbanks caused by "water and air displacement" due to the sharp rise in river water levels after a long drought, and eliminates potential safety hazards to dikes.

[0007] A device for venting and mitigating hazards in the surface soil of riverbanks includes: The exhaust pipe section and the exhaust flower pipe section are interconnected, and the bottom of the exhaust pipe section is buried in the weakly permeable stratum of the river beach. The top of the exhaust pipe section is sealed by a top sealing plate to prevent rainwater from entering the stratum; a horizontal exhaust hole higher than the design flood level is set on the side of the top of the exhaust pipe section to discharge the gas in the river beach stratum; The exhaust pipe section is buried in a layer of sand and gravel. The top of the exhaust pipe section is connected to the bottom of the solid exhaust pipe section. The perimeter is wrapped with nylon mesh and then sealed with filter sand. The nylon mesh and filter sand together form a filter relationship to prevent sand particles from the filter sand from entering the exhaust pipe section. The bottom of the exhaust pipe section is sealed by a bottom sealing plate to prevent soil particles from the sand and gravel layer from entering the gas pipe and to ensure that the gas in the vadose zone of the sand and gravel stratum gathers in the exhaust pipe section through the filter sand and is discharged smoothly.

[0008] Furthermore, the exhaust solid pipe section and the exhaust flower pipe section are different functional sections of the same pipe material. The pipe material is a plastic pipe or stainless steel pipe with a diameter of 20~40cm, and the opening rate of the exhaust flower pipe section is not less than 15%.

[0009] Furthermore, the exhaust port is 50cm to 200cm above the design flood level.

[0010] Furthermore, the horizontal exhaust vent is protected by an orifice filter to prevent insects, birds, or debris from entering and clogging it.

[0011] Furthermore, the filter screen is made of nylon mesh with a mesh size of 60-100.

[0012] Furthermore, the bottom outer periphery of the exhaust pipe section is tightly wrapped with a sealing clay layer, which seals the gap between the weakly permeable soil layer and the exhaust pipe, preventing rainwater or river water from infiltrating and gas from laterally escaping.

[0013] Furthermore, the spacing between the exhaust pipes in the surface soil of the river beach along the direction of the embankment is 20m to 40m, and the depth of the exhaust pipe section into the sand and gravel layer is 10m to 20m.

[0014] A method for venting surface soil in riverbanks, employing the aforementioned venting and hazard mitigation device for surface soil in riverbanks, the method comprising: When the river rises sharply, the compressed gas in the sand and gravel layer passes through the filter sand layer, nylon mesh, exhaust pipe section, and exhaust pipe section in sequence and is discharged from the horizontal exhaust port to avoid "gas erosion" damage to the surface soil of the river beach. When the river water drops sharply, the atmosphere enters the sand and gravel layer through the exhaust channel to balance the air pressure and prevent the surface soil from collapsing due to negative pressure erosion.

[0015] This invention enables the release of gases stored in the vadose zone formed by the sand and gravel layer in riverbank strata under prolonged drought conditions when the river water level is low. In the event of a sudden downpour, the river water level rises sharply, and the river overflows its banks, creating a gas-sealed environment in the riverbank strata. Under the influence of seepage pressure, the groundwater infiltration line continues to rise, displacing the gases. The gases originally stored in the sand and gravel vadose zone can be normally released through this gas release and hazard removal device, preventing the accumulation of gas pressure from damaging the riverbank strata. This eliminates the safety hazard of piping within the dike caused by the shortened seepage path of the dike foundation and also solves the problem of flood control safety for the dike. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the air venting and hazard mitigation device for the surface soil of riverbanks under long-term drought (dry season) conditions according to an embodiment of the present invention. Figure 2 yes Figure 1 Enlarged view of section A in the middle; Figure 3 This is a schematic diagram of the air venting and hazard mitigation device for the surface soil of riverbanks in an embodiment of the present invention under the condition of a sudden rainstorm and a sharp rise in river water level; Figure 4 yes Figure 3 Enlarged view of section B.

[0017] The reference numerals in the attached diagram are described as follows: 1-Exhaust pipe section; 2-Exhaust perforated pipe section; 3-Exhaust port; 4-Top sealing plate; 5-Bottom sealing plate; 6-Orifice filter screen; 7-Sealing clay layer; 8-Reverse filter sand layer; 9-Nylon mesh; 10-Elevation; 11-Weakly permeable soil layer of riverbank; 12-Sand and gravel layer; 13-Initial phreatic line of groundwater; 14-Saturated zone of sand and gravel layer; 15-Vacuum zone of sand and gravel layer; 16-River water level during dry season; 17-Design flood level; 18-River water level after steep rise; 19-Poreline during displacement period. Detailed Implementation

[0018] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings.

[0019] Please refer to Figures 1 to 4 This invention provides a device and method for venting and mitigating hazards in the surface soil of riverbanks; it includes an interconnected venting solid pipe section 1 and an venting perforated pipe section 2.

[0020] The bottom of the exhaust pipe section 1 is buried in the weakly permeable stratum 11 of the riverbank surface, and the perimeter is sealed with sealing clay 7 to prevent water or air leakage. A top sealing plate 4 is installed on the top of the exhaust pipe section 1 to prevent rainwater from entering the stratum. A horizontal exhaust port 3, higher than the design flood level 17, is installed on the side of the top of the exhaust pipe section 1 to ensure normal operation even when the design flood level is reached. The horizontal exhaust port 3 is protected by a filter screen 6 to prevent insects and birds from entering, and is used to expel gases from the riverbank stratum.

[0021] The exhaust pipe section 2 is buried in the gravel layer 12. The top of the exhaust pipe section 2 is connected to the bottom of the exhaust pipe section 1. The perimeter is wrapped with nylon mesh 9 and then sealed with filter sand 8. The nylon mesh 9 and the filter sand 8 together form a filter relationship to prevent sand particles from the filter sand 8 from entering the exhaust pipe section 2. The bottom of the exhaust pipe section 2 is sealed by a bottom sealing plate 5 to prevent soil particles from the gravel layer from entering the gas pipe and to ensure that the gas in the gas-sealed zone 15 of the gravel stratum gathers in the exhaust pipe section 2 through the filter sand 8 and is discharged smoothly.

[0022] The height of the exhaust port 3 should be 50cm to 200cm above the design flood level 17 of the dike 10 to prevent floods or waves from entering the exhaust port.

[0023] The exhaust pipe section 1 and the exhaust perforated pipe section 2 can be formed by drilling holes in one section of the same pipe. Referring to the experience of drainage and pressure relief well engineering on the back side of the dike, the exhaust pipe can be made of plastic pipe or stainless steel pipe with a diameter of 20~40cm. The opening rate of the perforated pipe section is not less than 15%. Depending on the geological conditions, it can be wrapped with 60~100 mesh nylon mesh twice. The spacing along the dike direction is 20m~40m, and the depth is 12m deep into the sand and gravel layer and 10m~20m deep.

[0024] The specific design parameters of the exhaust device are determined based on a comprehensive analysis of the dike characteristics, geological conditions of the riverbank, hydrological parameters, and the risk characteristics of "water-gas displacement," in order to ensure efficient exhaust, structural stability, and ultimately achieve the goal of dike hazard mitigation.

[0025] The working principle of this invention is as follows: under long-term drought conditions, such as Figure 1 As shown, during the dry season, the river water level 16 is located at the exposed position of the sand and gravel layer 12, which is relatively low. Correspondingly, the initial groundwater infiltration line 13 is also relatively low. Using the initial groundwater infiltration line 13 as a boundary, the lower side is the saturated zone 14 of the sand and gravel layer, and the upper side is the vadose zone 15 of the sand and gravel layer, which covers a relatively large area. Figure 3As shown, if a sudden downpour occurs, the river water rises rapidly. After a sharp rise, the river water level 18 submerges the weakly permeable soil layer 11 on the riverbank and reaches the toe of the levee 10. At this point, the river water forms a closed condition from the riverbank to the levee toe. The river water above the weakly permeable soil layer 11 seeps downwards, but because the surface soil of the riverbank has low permeability, the downward seepage speed is extremely slow. However, the sand and gravel layer 12 has high permeability, usually more than 1000 times that of the weakly permeable soil layer 11. Driven by the river water level 18 after the sharp rise, the initial phreatic line 13 of the groundwater in the sand and gravel layer 12 rises rapidly, forming a new phreatic line 1 during the water-vapor displacement period. 9. The groundwater-gas displacement process is formed, also known as the "water-gas displacement period". During this process, the saturated zone 14 of the sand and gravel layer continuously expands, while the vadose zone 15 of the sand and gravel layer is continuously compressed. Driven by gas compression, the gas pressure in the vadose zone 15 of the sand and gravel layer continuously increases. If there is no exhaust device, it will break through the surface and be discharged from the weak permeable soil layer 11 of the river beach. If there is an exhaust device, it will gradually gather in the exhaust pipe 2 and be discharged smoothly to the surface, thereby solving the problem of the pressurized gas formed during the water-gas displacement process breaking through the weak permeable soil layer 11 of the river beach and protecting the flood control safety of the dike.

[0026] If the river water level drops rapidly from the high water level to the dry season water level 16, it is the reverse process of the aforementioned water-air displacement process. Due to the presence of the exhaust device, the sand and gravel layer 12 can be connected with the atmosphere, causing the groundwater in the sand and gravel layer 12 to drop rapidly and form the sand and gravel layer vadose zone 15, thereby ensuring the stability of the soil particles in the weakly permeable soil layer 11 of the river beach and avoiding the negative pressure erosion damage caused by the reverse process.

[0027] This invention solves the problem of gas pressure in the vadose zone of sand and gravel soil causing damage to the surface soil of riverbanks during the "water-gas displacement" process in the event of a sudden rise in river water levels after a long drought. It ensures the safety of dikes during the flood season and fills the gap in degassing and hazard mitigation methods in this type of scenario.

[0028] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A device for venting and mitigating hazards in the surface soil of riverbanks, characterized in that, include: The exhaust pipe section (1) and the exhaust flower pipe section (2) are connected to each other. The bottom of the exhaust pipe section (1) is buried in the weakly permeable stratum (11) of the river beach. The top of the exhaust pipe section (1) is sealed by a top sealing plate (4) to prevent rainwater from entering the stratum; a horizontal exhaust hole (3) higher than the design flood level (17) is set on the top side of the exhaust pipe section (1) to discharge the gas in the river beach stratum; The exhaust pipe section (2) is buried in the gravel layer (12). The top of the exhaust pipe section (2) is connected to the bottom of the exhaust pipe section (1). The perimeter is wrapped with nylon mesh (9) and then sealed with filter sand (8). The nylon mesh (9) and the filter sand (8) together form a filter relationship to prevent sand particles from the filter sand (8) from entering the exhaust pipe section (2). The bottom of the exhaust pipe section (2) is sealed by a bottom sealing plate (5) to prevent soil particles from the gravel layer from entering the gas pipe and to ensure that the gas in the gas-sealed zone (15) of the gravel stratum gathers in the exhaust pipe section (2) through the filter sand (8) and is discharged smoothly.

2. The air venting and removal device for surface soil in riverbanks as described in claim 1, characterized in that: The exhaust pipe section (1) and the exhaust flower pipe section (2) are different functional sections of the same pipe material. The pipe material is a plastic pipe or stainless steel pipe with a diameter of 20~40cm. The opening rate of the exhaust flower pipe section (2) is not less than 15%.

3. The air venting and removal device for surface soil in riverbanks as described in claim 1, characterized in that: The exhaust port (3) is 50cm to 200cm above the design flood level (17).

4. The air venting and removal device for surface soil in riverbanks as described in claim 1, characterized in that: The horizontal vent (3) is protected by a mesh screen (6) to prevent insects and birds from entering or debris from clogging it.

5. The air venting and removal device for surface soil in riverbanks as described in claim 4, characterized in that: The perforated filter screen (6) is made of nylon yarn with a mesh size of 60~100.

6. The air venting and removal device for surface soil in riverbanks as described in claim 1, characterized in that: The bottom outer periphery of the exhaust pipe section (1) is tightly wrapped by a sealing clay layer (7). The sealing clay layer (7) seals the gap between the weakly permeable soil layer (11) and the exhaust pipe, preventing rainwater or river water from infiltrating and gas from laterally escaping.

7. The air venting and removal device for surface soil in riverbanks as described in claim 1, characterized in that: The spacing between the exhaust pipes in the surface soil of the river beach along the direction of the embankment (10) is 20m to 40m, and the depth of the exhaust pipe section (2) into the sand and gravel layer (12) is 10m to 20m.

8. A method for venting surface soil in riverbanks, characterized in that, The method employs the air venting and hazard mitigation device for the surface soil of riverbanks as described in any one of claims 1-7, and includes: When the river rises sharply, the compressed gas in the sand and gravel layer (12) passes through the reverse filter sand layer (8), nylon mesh (9), exhaust flower pipe section (2), and exhaust solid pipe section (1) in sequence and is discharged from the horizontal exhaust port (3) to avoid "gas erosion" damage to the surface soil of the river beach. When the river water drops sharply, the atmosphere enters the sand and gravel layer (12) through the exhaust channel to balance the air pressure and prevent the surface soil from collapsing due to negative pressure erosion.

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