A method for excavating a compound section of a mountainous navigation channel

Abstract

The application discloses a mountainous navigation channel complex cross-section excavation method and belongs to the technical field of hydraulic engineering. The planned navigation depth H and the planned navigation width B of a navigation channel are determined according to navigation channel planning. A cross-section with insufficient water depth and a relatively narrow width is selected as a typical excavation cross-section. A typical calculation cross-section diagram is drawn according to the typical calculation measured terrain data points. A first excavation cross-section is excavated, and the first excavation cross-section is determined according to the typical calculation cross-section diagram. The excavation area of the first excavation cross-section is denoted as A11. A second excavation cross-section is excavated, and the excavation area of the second excavation cross-section is denoted as A12. The flow velocity reduction value of the typical calculation cross-section is calculated by assuming that the excavation area of the second excavation cross-section is A12 from small to large, until the flow velocity is reduced to the design requirement. The present application innovatively designs two cross-sections, which respectively meet the requirements of the navigation channel planning scale and the flow velocity reduction, and significantly reduces the water flow velocity, the earthwork excavation amount, the engineering cost and the earth dumping amount, and the environmental impact.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydraulic engineering, and particularly relates to a mountainous navigation channel complex section excavation method. BACKGROUND

[0002] The rapids and dangerous shoals in the mountainous navigation channel usually have the characteristics of steep slope and turbulent flow. Such complex hydrological and geomorphological conditions can easily pose a threat to the safe navigation of ships. Due to the excessive speed of the water flow, the ships are prone to lose control when sailing in this area, especially when sailing upstream. The large flow rate leads to insufficient power, making navigation difficult, and even possible collisions and grounding. Therefore, rapids and dangerous shoals have become the main navigation-obstructing problems in mountainous navigation channels. In order to improve the safety and navigability of the channel, the method of excavating a navigation channel is usually adopted in engineering, which increases the size of the channel section to improve the navigation conditions. Increasing the section size not only helps to increase the depth and width of the channel to achieve the planned channel size, but also effectively slows down the water flow, reducing the difficulty of ship operation in the rapids. This excavation measure not only ensures the safe navigation of ships, but also improves the overall navigation efficiency of the mountainous navigation channel, which is a common and important means in mountainous navigation channel regulation projects.

[0003] The current mountainous navigation channel section excavation method can improve the channel conditions in engineering practice, but still has many deficiencies and shortcomings, especially in terms of economy and efficiency. First of all, the existing technology often relies on large-scale earth excavation to increase the size of the channel section, trying to reduce the water flow rate by expanding the depth and width of the navigation channel. However, as the amount of earth excavation increases, the effect of reducing the flow rate shows a decreasing trend. When the excavation amount exceeds a certain limit, even if the size of the section is increased, the decline in flow rate will no longer be significant, which means that the excavation benefit has decreased dramatically and effective flow rate control cannot be achieved.

[0004] Secondly, excessive reliance on large-scale section excavation not only leads to poor flow rate control, but also brings significant engineering economic problems. Since earth excavation requires a large amount of manpower, machinery and other resources, as the amount of excavation increases, the engineering cost will also rise sharply. Especially in the complex mountainous terrain and variable geological conditions, the difficulty of excavation increases, leading to further increase in construction costs. In addition, excessive section excavation can also generate a large amount of spoil, which needs to be properly handled, otherwise it may have a negative impact on the surrounding ecological environment and river stability. The disposal process of spoil also increases the overall investment of the project, bringing additional pressure on the economic feasibility of the project.

[0005] In addition, excessive excavation can cause other potential problems, such as excessive cross-section changes the water dynamic characteristics of the river, which can cause new turbulent flow areas or unstable flow patterns, thereby bringing additional channel regulation problems. Furthermore, large-scale excavation is destructive to the riverbed, which can easily cause instability of the riverbed, thereby causing problems such as redistribution or erosion of sediments, thereby posing new challenges to the safety of the channel.

[0006] Therefore, it is urgent to propose a mountainous channel excavation method that can balance the channel regulation effect and economic feasibility. SUMMARY

[0007] In view of the problems existing in the prior art, the present application provides a mountainous channel complex cross-section excavation method which aims to solve the problems of non-proportionality between earthwork excavation amount and flow velocity reduction effect, high engineering investment, environmental and cost problems caused by spoil disposal, and deterioration of riverbed stability and water dynamic conditions caused by excessive excavation.

[0008] The present application is implemented as follows: a mountainous channel complex cross-section excavation method, characterized in that it comprises the following steps:

[0009] S1. determining the planned depth H and the planned width B of the channel according to the channel planning;

[0010] S2. selecting a cross-section with insufficient water depth and narrow width as a typical excavation cross-section;

[0011] S3. drawing a typical calculation cross-section diagram according to the typical calculation measured terrain data points;

[0012] S4. excavating the first excavation cross-section, determining the channel centerline point and the channel boundary position according to the typical calculation cross-section diagram, checking the water depth under the minimum navigable water level, determining the first excavation cross-section, and recording the excavation area of the first excavation cross-section as A 11 ;

[0013] S5. excavating the second excavation cross-section, setting the excavation area of the second excavation cross-section as A 12 , and trial calculating the flow velocity reduction value of the typical calculation cross-section by assuming that the excavation area of the second excavation cross-section is A12 from small to large, until the flow velocity is reduced to the design requirement.

[0014] In the above technical solution, preferably, according to the cross-section topographic map, the elevation of the minimum navigable water level is measured as △Z I , the upper boundary elevation of the first excavation cross-section is measured as △Z 11 , the bottom boundary elevation of the first excavation cross-section is measured as △Z 12 , and the cross-section area between the upper boundary of the first excavation cross-section and the original riverbed bottom boundary is recorded as A 01 ;

[0015] The minimum navigable water level is △ZI Depth h between the first trench section water level 11 02 is:

[0016]

[0017] Height h of the first trench section 11 is:

[0018] h 11 = H - h 02 (2)

[0019] Bottom boundary width b of the first trench section 12 Take the channel design width B, and:

[0020] b 12 = B (3)

[0021] Let the slope of the first trench section be m, then the upper boundary width b 11 of the first trench section is:

[0022]

[0023] The channel area below the upper boundary of the first trench section is:

[0024]

[0025] Excavation area A of the first trench section 11 :

[0026]

[0027] In the above technical solution, preferably, according to the measured data of the river section, the characteristic flow Q i to be calculated is determined, which must include the lowest navigable water level and the highest navigable water level;

[0028] The characteristic flow Q i is determined according to the hydrological analysis data, and the corresponding characteristic water level i ;

[0029] Corresponding to the i-th characteristic flow Q i , the water level is i , and the section area A i0 of the typical calculation section before excavation is measured from the section topographic map; from the section topographic map, the area A i02 enclosed by the characteristic water level i , the upper boundary 11 of the first trench section at the characteristic flow, and the typical calculation section can be measured and determined;

[0030] ​Before excavation of a typical calculation section under the i-th characteristic flow rate, the flow velocity V at the typical calculation section is... i0 for:

[0031]

[0032] After excavating the first and second trenches under the i-th characteristic flow rate, the area A of the typical calculated cross-section is... i1 for:

[0033] A i1 =A i02 +A 11 +A 12 (8)

[0034] After excavating the first and second trenches under the i-th characteristic flow rate, the flow velocity V at a typical calculation section is... i1 for:

[0035]

[0036] The velocity change ΔV at a typical calculation section after excavating the first and second trenches under the i-th characteristic flow rate. i for:

[0037]

[0038] In the above formula (10), i is taken as I at the lowest navigable water level, i is taken as II at the highest navigable water level, and several characteristic water levels are taken between the lowest and highest navigable water levels for calculation, i is denoted as III, IV, etc. Assume the excavation area A of the second trench is... 12j (j takes values ​​of 0, 1, 2, ...) and varies from small to large. Based on formulas (1) to (10), the velocity change ΔV at typical cross-sections after excavating the first and second trenches is calculated respectively. ij The change in flow velocity at the cross-section at the lowest navigable water level is ΔV. I The change in flow velocity at the cross-section at the highest navigable water level is ΔV. II The velocity change at other characteristic water levels is ΔV. III , △V IV ...

[0039] In the above technical solution, preferably, the excavation area A of the second trench is plotted as the excavation area of ​​the second trench gradually increases. 12j The velocity change ΔV at a typical calculation section ij The relationship curve between A and B; based on the relationship curve, find the relationship curve that follows A. 12j Increase △V ij The inflection point when the characteristic flow rate i remains essentially unchanged is denoted as K. i The corresponding excavation area of ​​the second trench is A.12iK , the flow velocity variation value ΔV of a typical calculation section iK . The excavation area of the second trench corresponding to the inflection point when comparing different characteristic working conditions i is A 12iK , the maximum value of which is taken as the excavation area A of the second trench 12 .

[0040] The mountainous area navigation trench compound section excavation method proposed by the present technology realizes the effective consideration of the satisfaction of the navigation planning scale and the reduction of the flow velocity by innovatively designing two excavation sections, and overcomes the problems of high investment, limited flow velocity reduction effect and increased spoil amount caused by large-scale excavation in the prior art. Its advantages and effects are reflected in multiple aspects:

[0041] Firstly, the method clearly proposes to excavate two sections to meet different needs, i.e. one section is used to ensure the planning scale of the navigation channel, and the other section is used to reduce the flow velocity. This clear division of labor design has high pertinence in section planning, making the function of each section clear and the target clear, so as to more effectively control the flow velocity and adjust the size of the navigation channel. Compared with the traditional single-section excavation method, the design of the compound section avoids unnecessary over-excavation, and can achieve the same or even better navigation improvement effect with less earthwork excavation amount.

[0042] Secondly, through this compound section structure, the flow velocity of the section can be significantly reduced, effectively improving the navigation safety of ships in mountainous rapids and dangerous shoal areas. Traditional methods often increase the excavation amount when facing complex flow conditions, but the flow velocity reduction effect is limited. The present technology reduces the water flow velocity by reasonably setting the size and shape of the second section, thereby relieving the difficulty of ship operation in rapids, especially when landing, which can significantly reduce the power shortage and operation errors caused by excessive flow velocity.

[0043] In addition, this compound section excavation method has good economy. By optimizing the excavation design, unnecessary large-scale earthwork excavation is avoided, directly reducing the investment and resource input required for the project. Since excessive excavation is no longer needed to achieve the goal of reducing the flow velocity, the total excavation amount of the project is significantly reduced, thereby reducing the construction cost. At the same time, due to the reduction of the earthwork excavation amount, the spoil amount is also reduced, thereby reducing the cost and environmental impact of spoil disposal. For such a complex environment as a mountainous river, the disposal of spoil is usually an expensive and time-consuming engineering problem, and the present technology indirectly improves the economic feasibility of the entire project by reducing the amount of spoil.

[0044] In addition, this method also takes into account environmental protection and engineering sustainability. While reducing the amount of earth excavation and spoil, it minimizes the disturbance to the riverbed and the surrounding ecological environment. Excessive disturbance during river regulation can lead to riverbed instability, which in turn can trigger new hydrological and ecological problems. By optimizing the excavation strategy, this technology minimizes the disturbance to the river channel, ensuring the effectiveness of the channel regulation and maintaining the stability of the river ecosystem.

[0045] Finally, this method also has strong adaptability and flexibility. Since the excavation area of the second section is determined by calculating the flow velocity variation curve under different characteristic flow rates, this technology can flexibly adjust the construction plan according to specific hydrological conditions, river characteristics and navigation requirements, ensuring that the section design meets the actual needs and avoids unnecessary resource waste. This high degree of flexibility enables the method to adapt to different types of mountainous river channels, enhancing its application range in practical engineering.

[0046] In summary, the mountainous navigation channel compound section excavation method proposed by this technology has significant advantages in terms of channel regulation effect, flow rate control, economy, environmental protection and adaptability. It not only effectively meets the requirements of channel planning scale, but also significantly reduces the flow rate, ensuring the safety of ship navigation, and to the greatest extent, reduces the engineering cost and environmental impact. It is an innovative mountainous navigation channel regulation scheme that takes into account economic benefits and engineering effects. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a schematic diagram of excavation parameters;

[0048] Figure 2 is a schematic diagram of the relationship between the second excavation slot excavation surface and the variation of the section flow rate under the minimum navigation water level;

[0049] Figure 3 is a schematic diagram of the relationship between the second excavation slot excavation surface and the variation of the section flow rate under the maximum navigation water level;

[0050] Figure 4 is a schematic diagram of the relationship between the second excavation slot excavation surface and the variation of the section flow rate under the normal water level;

[0051] Figure 5 is a schematic diagram of the relationship between the second excavation slot excavation surface and the variation of the section flow rate under the characteristic working condition i. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present application clearer and more apparent, the following embodiments are used to further explain the present application. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0053] To solve the problems of the earthwork excavation quantity and the flow rate reduction effect not being proportional, high engineering investment, environmental and cost problems caused by abandoned soil treatment, and the riverbed stability and hydrodynamic conditions deterioration caused by excessive excavation, the present application provides a mountainous navigation channel complex section excavation method, which realizes the significant reduction of water flow rate, the reduction of earthwork excavation quantity, the reduction of engineering cost and abandoned soil quantity, the reduction of environmental impact, and has strong flexible adaptability and economic feasibility by innovatively designing two sections to meet the navigation channel planning scale and the flow rate reduction demand. In order to further illustrate the structure of the present application, the detailed description is as follows in combination with the drawings:

[0054] Please refer to Figure 1 A mountainous navigation channel complex section excavation method, comprising the following steps:

[0055] S1. According to the navigation channel planning condition of the research river section, the planned navigation depth H and the navigation width B of the navigation channel are determined.

[0056] S2. According to the measured topographic map of the river channel, a typical excavation section with insufficient water depth and narrow section is selected.

[0057] S3. According to the typical calculation measured topographic data points, a typical calculation section drawing is drawn.

[0058] The above is the existing conventional technology, and the following is the new technology proposed by the present application. The mountainous river generally has the problems of unsatisfied navigation channel planning scale and rapid navigation channel flow rate, and the existing technology generally excavates one section to meet the planning navigation channel scale and reduce the flow rate of the section, which has the problems of excessive excavation quantity and high engineering cost. Two sections are excavated this time, one excavation section A 11 is used to meet the navigation channel planning scale, and the other excavation section A 12 is used to reduce the water flow rate.

[0059] S4. According to the typical calculation section drawing, the navigation channel centerline point and the navigation channel boundary position are determined, the water depth under the lowest navigable water level is checked, the first excavation section is determined, and the excavation area of the first excavation section is recorded as A 11 to meet the navigation channel planning scale. According to the section topographic map, the elevation △Z I corresponding to the lowest navigable water level is measured, the upper boundary elevation △Z 11 of the first excavation section is measured, and the bottom boundary elevation △Z 12 of the first excavation section is measured. The section area between the upper boundary of the first excavation section and the original riverbed bottom boundary is recorded as A 01 .

[0060] The depth h I between the lowest navigable water level △Z 11 and the water level △Z 02 of the first excavation section is:

[0061]

[0062] The height h of the first excavated section 11 for:

[0063] h 11 =Hh 02 (2)

[0064] The bottom boundary width b of the first excavation section 12 Taking the design width B of the waterway, we have:

[0065] b 12 =B (3)

[0066] Let the slope of the first excavated section be m, then the width of the upper boundary of the first excavated section is b. 11 for:

[0067]

[0068] The area of ​​the navigation channel below the boundary of the first excavated section is:

[0069]

[0070] The excavation area A of the first trench section 11 :

[0071]

[0072] Let the trench excavated to reduce the flow velocity in the navigation channel be the second trench, and let the excavation area of ​​the second trench be A. 12 By assuming the excavation area of ​​the second trench is A 12 Starting from small values, calculate the velocity reduction at typical calculation sections until the velocity decreases to the required level, and as A... 12 As the value increases, the decrease in flow velocity at the calculated cross-section does not change significantly.

[0073] S5. Based on the measured data of the studied river section, determine the characteristic flow rate Q that needs to be calculated. i The data must include both the minimum and maximum navigable water levels. Other intermediate characteristic flows, such as normal water levels, can be determined based on the channel improvement needs of the studied river section. The characteristic flow Q is determined according to hydrological analysis data. i Corresponding characteristic water level ▽Z i .

[0074] Corresponding to the i-th characteristic flow Q i The corresponding water level is ▽Z i The cross-sectional area A of a typical calculated section before excavation was obtained by measuring from the cross-sectional topographic map. i0 The characteristic water level ▽Z can be measured and determined from the cross-sectional topographic map.i , the upper boundary of the first trench section of the characteristic flow 11 The area A enclosed between the typical calculation section and i02 .

[0075] The flow velocity V of the typical calculation section before excavation under the i-th characteristic flow i0 is:

[0076]

[0077] The area A of the typical calculation section after excavation of the first trench and the second trench under the i-th characteristic flow i1 is:

[0078] A i1 = A i02 + A 11 + A 12 (8)

[0079] The flow velocity V of the typical calculation section after excavation of the first trench and the second trench under the i-th characteristic flow i1 is:

[0080]

[0081] The flow velocity change value AV of the typical calculation section after excavation of the first trench and the second trench under the i-th characteristic flow i is:

[0082]

[0083] In the above formula (10), i takes I at the lowest navigation water level, i takes II at the highest navigation water level, and i takes III, IV, … for calculation at several characteristic water levels between the lowest navigation water level and the highest navigation water level. It is assumed that the excavation area A 12j of the second trench (j takes 0, 1, 2, …) changes from small to large, and the flow velocity change value AV of the typical calculation section after excavation of the first trench and the second trench is calculated according to the formula (1) to the formula (10) respectively. ij The flow velocity change value AV of the section at the lowest navigation water level is AV I , the flow velocity change value AV of the section at the highest navigation water level is AV II , and the flow velocity change value AV of the section at other characteristic water levels is AV III , AV IV ……。The relationship curve between the excavation area A 12j of the second trench and the flow velocity change value AV ij of the typical calculation section is drawn as the excavation area of the second trench gradually increases.

[0084] Under the first working condition and at the lowest navigable water level (denoted as i), plot the excavation area A of the second trench. 12j The velocity change ΔV at a typical calculation section Ij A diagram illustrating the relationship curves, such as... Figure 2 .

[0085] Under the second operating condition and at the lowest navigable water level (denoted as i as II), plot the excavation area A of the second trench. 12j The velocity change ΔV at a typical calculation section IIj A diagram illustrating the relationship curves, such as... Figure 3 .

[0086] Other working conditions depend on the riverbed evolution characteristics and hydrological conditions of the studied river section. Assuming the third working condition is at a normal water level, under the normal water level (denoted as III), draw the excavation area A of the second trench. 12j The velocity change ΔV at a typical calculation section IIIj A diagram illustrating the relationship curves, such as... Figure 4 .

[0087] like Figure 5 The excavation area A of the second trench under various working conditions i 12j The velocity change ΔV at a typical calculation section ij The relationship curve between A and B can be used to find the relationship between A and B. 12j Increase △V ij The inflection point when the characteristic flow rate i remains essentially unchanged is denoted as K. i The corresponding excavation area of ​​the second trench is A. 12iK The velocity variation ΔV at a typical calculation section iK The excavation area of ​​the second trench corresponding to the inflection point under different characteristic working conditions i is A. 12iK The maximum value among them is taken as the excavation area A of the second trench. 12 .

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for excavating a double-section navigation channel in mountainous areas, characterized in that, Includes the following steps: S1. Determine the planned navigation depth H and planned navigation width of the waterway based on the waterway planning. B ; S2. Select a cross-section with insufficient water depth and a relatively narrow width as a typical trench cross-section; S3. Draw typical calculated cross-section diagrams based on typical calculated and measured topographic data points; S4. Excavate the first trench section. Based on the typical calculated cross-section diagram, determine the centerline point of the navigation channel and the position of the channel edge line. Verify the water depth below the lowest navigable water level, determine the first trench section, and denote the excavation area of ​​the first trench section as... A 11 ; S5. Excavate the second trench section, and let the excavation area of ​​the second trench section be A. 12 By assuming the excavation area of ​​the second trench section is A 12 From small to large, calculate the velocity reduction value of typical calculation sections until the velocity is reduced to the design requirement; Based on the cross-sectional topographic map, measure the elevation corresponding to the lowest navigable water level. Z I Measure the boundary elevation on the first excavation section ▽ Z 11 Measure the elevation of the bottom boundary of the first excavation section. Z 12 Let the cross-sectional area between the upper boundary of the first excavation section and the original riverbed bottom boundary be denoted as . A 01 ; Minimum navigable water level ▽ Z I Water level at the first excavation section ▽ Z 11 Depth between h 02 for: （1） The height of the first excavation section h 11 for: （2） Width of the bottom boundary of the first excavation section b 12 Take the design width of the waterway B ,have: （3） Let the slope of the first excavated section be... m The upper boundary width of the first excavation section is... b 11 for: （4） The area of ​​the navigation channel below the boundary of the first excavated section is: （5） Excavation area of ​​the first trench section A 11 : （6）； Based on the measured data of the river section, the characteristic flow rate that needs to be calculated is determined. Q i It must include both the minimum and maximum navigable water levels; Determine the characteristic flow rate based on hydrological analysis data. Q i Corresponding characteristic water level ▽ Z i ; Corresponding to the i Characteristic flow Q i The corresponding water level is ▽ Z i The cross-sectional area of ​​a typical calculated section before excavation was obtained by measuring it from the cross-sectional topographic map. A i0 The characteristic water level can be measured and determined from the cross-sectional topographic map. Z i ▽ Boundary of the first trench section under characteristic flow Z 11 The area enclosed between the typical calculation section and the cross section A i02 ; No. i Before excavation, the flow velocity at a typical calculation section under a certain characteristic flow rate is... V i0 for: （7） No. i After excavating the first and second trenches under a certain characteristic flow rate, the area of ​​a typical calculated cross-section is... A i1 for: （8） No. i After excavating the first and second trenches under certain characteristic flow rates, the flow velocity at a typical calculation section is... V i1 for: （9） No. i After excavating the first and second trenches under a certain characteristic flow rate, the velocity change Δ at a typical calculation section is calculated. V i for: （10） In the above formula (10), i Take I at the lowest navigable water level. i Take II as the highest navigable water level, and calculate using several characteristic water levels between the lowest and highest navigable water levels. i They are respectively labeled III, IV, ...; assuming the excavation area of ​​the second trench... A 12j , j Using values ​​0, 1, 2, ..., from smallest to largest, calculate the velocity change Δ at typical cross-sections after excavating the first and second trenches according to formulas (1) to (10). V ij The change in flow velocity at the cross-section at the lowest navigable water level is Δ V I The change in flow velocity at the cross-section at the highest navigable water level is Δ V II The velocity change at other characteristic water levels is Δ V III , △ V IV ...

2. The method for excavating a double-section channel in mountainous areas according to claim 1, characterized in that: The plot shows the excavation area of ​​the second trench as the excavation area gradually increases. A 12j The velocity change Δ at a typical calculation section V ij The relationship curve, based on the relationship curve, find the following A 12j Increase △ V ij The inflection point when the fundamental value remains unchanged is denoted as the characteristic flow. i At that time, the inflection point was K i The corresponding excavation area of ​​the second trench is A 12iK The velocity variation Δ at a typical calculation section V iK Comparison of different characteristic working conditions i The excavation area of ​​the second trench corresponding to the inflection point is A 12iK The maximum value among them is taken as the excavation area of ​​the second trench. A 12 .

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