Compound section excavation method for channel in mountainous area

Abstract

The invention discloses a mountainous area channel compound section excavation method, which belongs to the technical field of water conservancy projects, and comprises the following steps: determining a planned channel depth H and a planned channel width B of a channel according to channel planning; selecting a narrow section with insufficient water depth as a typical grooving section; according to topographic data points measured by typical calculation, drawing a typical calculation cross-section diagram; a first grooving section is excavated, the first grooving section is determined according to the typical calculation section diagram, and the excavation area of the first grooving section is recorded as A11; and a second grooving section is excavated, the excavation area of the second grooving section is set to be A12, and by assuming that the excavation area of the second grooving section is A12 from small to large, the flow velocity reduction value of the typical calculation section is trying to be calculated until the flow velocity is reduced to the design requirement. According to the technology, the two sections are innovatively designed, the requirements for the channel planning scale and flow velocity reduction are met respectively, the water flow velocity is remarkably reduced, the earthwork excavation amount is reduced, the engineering cost and the spoil amount are reduced, and the environmental influence is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy engineering, and in particular relates to a method for excavating a complex section of a navigation channel in a mountainous area. Background Art

[0002] Rapids and dangerous shoals in mountain waterways are usually characterized by steep slopes and turbulent water flow. This complex hydrological landform can easily pose a threat to the safe navigation of ships. Due to the high speed of the water flow, ships are prone to lose control when sailing in this area, especially when sailing upstream. The high speed of the flow leads to insufficient power, navigation difficulties, and even the possibility of collision, grounding and other dangers. Therefore, rapids and dangerous shoals have become the main obstacles to navigation in mountain waterways. In order to improve the safety and navigation capacity of waterways, engineering projects usually adopt the method of excavating navigation channels to improve navigation conditions by increasing the cross-sectional dimensions of the waterway. Increasing the cross-section not only helps to increase the water depth and width of the waterway, thereby achieving the waterway scale required by the planning, but also can effectively slow down the water flow speed and reduce the difficulty of ship operation in rapids. This excavation measure can not only ensure the safe navigation of ships, but also improve the overall navigation efficiency of mountain waterways. It is a common and important means in mountain waterway regulation projects.

[0003] Although the current method of excavating channel sections in mountainous areas can improve waterway conditions in engineering practice, it 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 velocity by expanding the depth and width of the channel. However, as the amount of earth excavation continues to increase, its effect on slowing down the flow rate shows a decreasing trend. When the excavation volume exceeds a certain limit, even if the scale of the section continues to increase, the decrease in flow velocity becomes less obvious, which means that the excavation efficiency drops sharply and effective flow velocity control cannot be achieved.

[0004] Secondly, over-reliance on large-scale cross-section excavation not only leads to poor flow rate control effects, but also brings significant engineering economic problems. Since earthwork excavation requires a lot of manpower, machinery and other resources, as the amount of excavation increases, the cost of the project will also rise sharply. Especially in mountainous areas with complex terrain and changeable geological conditions, the difficulty of trenching operations increases, leading to further increases in construction costs. In addition, excessive cross-section excavation may also produce a large amount of waste soil, 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 waste soil also increases the overall investment of the project, bringing additional pressure to the economic feasibility of the project.

[0005] In addition, excessive excavation may cause other potential problems. For example, an overly large cross-section changes the hydrodynamic characteristics of the river, which may cause new areas of turbulent water flow or unstable flow patterns, thus bringing additional difficulties in waterway regulation. Furthermore, large-scale excavation is highly destructive to the riverbed, which can easily cause instability in the riverbed, leading to problems such as redistribution or erosion of sediments, which in turn poses new challenges to waterway safety.

[0006] Therefore, it is urgent to propose a navigation channel excavation method in mountainous areas that can take into account both the channel regulation effect and economic feasibility. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for excavating a complex section of a navigation channel in a mountainous area, which aims to solve the problems that the amount of earth excavation is not proportional to the flow velocity slowing effect, the high engineering investment, the environmental and cost problems caused by the disposal of abandoned earth, and the excessive excavation may cause the deterioration of riverbed stability and hydrodynamic conditions.

[0008] The present invention is implemented as follows: a method for excavating a complex cross-section of a navigation channel in a mountainous area, characterized in that it comprises the following steps:

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

[0010] S2. Select a narrow section with insufficient water depth as a typical trenching section;

[0011] S3. Draw a typical calculation cross-section diagram based on typical calculated measured terrain data points;

[0012] S4. Excavate the first trench section. According to the typical calculation section diagram, determine the centerline point of the channel and the position of the channel edge line, check the water depth under the lowest navigable water level, determine the first trench section, and record the excavation area of ​​the first trench section as A. 11 ;

[0013] S5. Excavate the second trench section. Assume that the excavation area of ​​the second trench section is A. 12 By assuming that the excavation area of ​​the second trench section is A12 from small to large, the flow velocity reduction value of the typical calculation section is calculated until the flow velocity is reduced to the design requirement.

[0014] In the above technical solution, preferably, according to the cross-sectional topographic map, the elevation ▽Z corresponding to the lowest navigable water level is measured. I , measure the boundary elevation ▽Z on the first trench section 11 , measure the bottom boundary elevation of the first trench section ▽Z 12 , let the cross-sectional area between the upper boundary of the first trench section and the original riverbed bottom boundary be A 01 ;

[0015] Minimum navigable water level ▽ZI The water level of the first trench section ▽Z 11 The depth between 02 for:

[0016]

[0017] The height of the first groove section h 11 for:

[0018] h 11 =Hh 02 (2)

[0019] The bottom boundary width b of the first groove section 12 Taking the designed width of the channel B, we have:

[0020] b 12 =B (3)

[0021] Assume that the slope of the first groove section is m, then the upper boundary width b of the first groove section is 11 for:

[0022]

[0023] The area of ​​the navigation groove 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, the characteristic flow Q to be calculated is determined based on the measured data of the river section. i , must include the lowest navigable water level and the highest navigable water level;

[0028] Determine characteristic flow Q based on hydrological analysis data i Corresponding characteristic water level ▽Z i ;

[0029] Corresponding to the i-th characteristic flow Q i , the corresponding water level is ▽Z i , the cross-sectional area A of the typical calculated cross-section before excavation is measured from the cross-sectional topographic map i0 ; From the cross-sectional topographic map, the characteristic water level ▽Z can be measured and determined i , the upper boundary of the first groove section under characteristic flow ▽Z 11 The area A enclosed by the typical calculation section i02 ;

[0030] The velocity V of the typical calculation section before excavation under the i-th characteristic flow rate i0 for:

[0031]

[0032] The area A of the typical calculated section after the first and second trenches are excavated under the i-th characteristic flow rate i1 for:

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

[0034] The velocity V of the typical calculation section after the first and second trenches are excavated under the i-th characteristic flow rate i1 for:

[0035]

[0036] The velocity change value △V of the typical calculation section after the first and second trenches are excavated under the i-th characteristic flow rate i for:

[0037]

[0038] In the above formula (10), i is I at the lowest navigable water level, and II at the highest navigable water level. Several characteristic water levels between the lowest and highest navigable water levels are taken for calculation, and i is recorded as III, IV, etc. Assume that the excavation area A of the second trench is 12j (j takes 0, 1, 2...) and changes from small to large. According to formula (1) to formula (10), the velocity change value △V of the typical calculation section after the first trench and the second trench are respectively calculated. ij , the velocity change value of the cross section at the lowest navigable water level is △V I , the velocity change value of the cross section at the highest navigable water level is △V II , the flow velocity change value of the cross section at other characteristic water levels is △V III , △V IV …….

[0039] In the above technical solution, preferably, when the excavation area of ​​the second trench gradually increases, the excavation area A of the second trench is plotted. 12j The velocity change value △V of the typical calculation section ij According to the relationship curve, find the 12j Increase △V ij The inflection point when the characteristic flow rate is basically unchanged is K i , the corresponding excavation area of ​​the second trench is A12iK , the velocity change value of the typical calculation section △V iK When comparing different characteristic working conditions i, the excavation area of ​​the second groove corresponding to the inflection point is A 12iK , take the maximum value as the excavation area A of the second trench 12 .

[0040] The complex cross-section excavation method for navigation channels in mountainous areas proposed by this technology achieves an effective balance between meeting the channel planning scale and reducing the flow velocity by innovatively designing two excavation sections, overcoming the problems of high investment, limited flow velocity reduction effect, and increased amount of abandoned soil caused by large-scale excavation in the existing technology. Its advantages and effects are reflected in many aspects:

[0041] First, the method clearly proposes to meet different needs by excavating two sections, that is, one section is used to ensure the planned scale of the waterway, and the other section is used to reduce the flow rate. This design with clear division of labor is highly targeted in section planning, making the function and goal of each section clear, so that the flow rate can be controlled more effectively and the size of the waterway can be adjusted. Compared with the traditional single-section excavation method, the compound section design avoids ineffective over-excavation and can achieve the same or even better waterway reconstruction effect with less earth excavation.

[0042] Secondly, this composite cross-section structure can significantly reduce the water flow velocity of the cross-section, effectively improving the navigation safety of ships in mountainous rapids and dangerous shoals. Traditional methods often increase the amount of excavation when facing complex water flow conditions, but the effect of slowing down the flow velocity is limited. This technology can significantly reduce the water flow velocity by reasonably setting the size and shape of the second cross-section, thereby alleviating the difficulty of maneuvering ships when sailing in rapids, especially when going ashore, it can significantly reduce the lack of power and operational errors caused by excessive flow velocity.

[0043] In addition, this compound section excavation method has good economic efficiency. By optimizing the excavation design, unnecessary large-scale earth excavation is avoided, which directly reduces the investment and resource input required for the project. Since excessive excavation is no longer required to achieve the goal of reducing flow velocity, the total excavation volume of the project is significantly reduced, thereby reducing construction costs. At the same time, due to the reduction in earth excavation, the amount of abandoned soil is also reduced, thereby reducing the cost and environmental impact of abandoned soil disposal. For complex environments such as mountain rivers, the disposal of abandoned soil is usually an expensive and time-consuming engineering problem, and this technology indirectly improves the economic feasibility of the entire project by reducing the amount of abandoned soil.

[0044] In addition, this method also takes into account environmental protection and engineering sustainability. While reducing the amount of earth excavation and abandoned soil, it minimizes the interference with the riverbed and surrounding ecological environment. Excessive disturbance during river regulation may lead to unstable riverbeds, which in turn may cause new hydrological and ecological problems. This technology minimizes the interference of the project on the river channel by optimizing the excavation strategy, which not only ensures the regulation effect of the waterway, but also maintains the stability of the river ecosystem.

[0045] Finally, this method is highly adaptable and flexible. Since the excavation area of ​​the second section is determined by calculating the velocity change curve under different characteristic flow rates, this technology can flexibly adjust the construction plan according to specific hydrological conditions, river characteristics, and navigation needs, ensuring that the section design meets actual needs and avoiding unnecessary waste of resources. This high degree of flexibility enables this method to adapt to different types of mountain rivers, increasing its scope of application in actual engineering.

[0046] In summary, the complex section excavation method of mountain channel proposed by this technology has significant advantages in terms of channel regulation effect, flow velocity control, economy, environmental protection and adaptability. It can not only effectively meet the requirements of channel planning scale, but also significantly reduce the flow velocity, ensure the safety of ship navigation, and minimize engineering costs and environmental impacts. It is an innovative mountain channel regulation plan that takes into account both economic benefits and engineering effects. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0048] Figure 2 This is a schematic diagram of the relationship between the excavation surface of the second trench and the change in cross-sectional flow velocity at the lowest navigable water level;

[0049] Figure 3 This is a schematic diagram of the relationship between the excavation surface of the second trench and the change in cross-sectional flow velocity at the highest navigable water level;

[0050] Figure 4 It is a schematic diagram of the relationship between the excavation surface of the second trench and the flow velocity change value of the cross section under normal water level;

[0051] Figure 5 Schematic diagram of the relationship between the second trench excavation surface and the cross-sectional flow velocity change value under characteristic working condition i. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] In order to solve the problems that the amount of earthwork excavation is not proportional to the effect of flow velocity reduction, the high investment in engineering projects, the environmental and cost problems caused by the disposal of abandoned soil, and the deterioration of riverbed stability and hydrodynamic conditions caused by excessive excavation, the present invention provides a method for excavating a mountain channel with a compound section. This technology innovatively designs two sections to meet the needs of waterway planning scale and flow velocity reduction, thereby significantly reducing water flow velocity, reducing earthwork excavation, reducing engineering costs and the amount of abandoned soil, and reducing environmental impact, and has strong flexibility, adaptability and economic feasibility. In order to further illustrate the structure of the present invention, the detailed description is as follows in conjunction with the attached drawings:

[0054] See also Figure 1 A method for excavating a complex cross-section navigation channel in a mountainous area comprises the following steps:

[0055] S1. According to the waterway planning of the studied river section, determine the planned navigation depth H and navigation width B of the waterway.

[0056] S2. According to the measured topographic map of the river channel, select the section with insufficient water depth and narrowness as the typical trenching section.

[0057] S3. Draw a typical calculated cross-section diagram based on typical calculated measured topographic data points.

[0058] The above are the existing conventional technologies, and the following are the new technologies proposed by this patent. Mountain rivers generally have the problems of unsatisfactory channel planning scale and rapid channel flow. The existing technology generally achieves the goal of meeting the planned channel scale and reducing the cross-section flow rate by excavating one section, which causes the problem of excessive cross-section excavation and excessive engineering costs. This patent proposes to excavate two sections, one excavation section A and one excavation section B. 11 To meet the waterway planning scale, another excavation section A 12 Used to meet the needs of reducing water flow rate.

[0059] S4. According to the typical calculation section diagram, determine the centerline point of the channel and the position of the channel edge line, check the water depth under the lowest navigable water level, determine the first trench section, and record the excavation area of ​​the first trench section as A. 11 According to the cross-sectional topographic map, the elevation corresponding to the lowest navigable water level is measured. I , measure the boundary elevation ▽Z on the first trench section 11 , measure the bottom boundary elevation of the first trench section ▽Z 12 The cross-sectional area between the upper boundary of the first trench section and the original riverbed bottom boundary is A. 01 .

[0060] Minimum navigable water level ▽Z I The water level of the first trench section ▽Z 11 The depth between 02 for:

[0061]

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

[0063] h 11 =Hh 02 (2)

[0064] The bottom boundary width b of the first groove section 12 Taking the designed width of the channel B, we have:

[0065] b 12 =B (3)

[0066] Assume that the slope of the first groove section is m, then the upper boundary width b of the first groove section is 11 for:

[0067]

[0068] The area of ​​the navigation groove below the upper boundary of the first trench section is:

[0069]

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

[0071]

[0072] The trench excavated to reduce the flow velocity in the navigation channel is called the second trench. The excavation area of ​​the second trench is A. 12 , by assuming that the excavation area of ​​the second trench is A 12 From small to large, calculate the velocity reduction value of the typical calculation section until the velocity is reduced to the demand, and as A 12 As the value increases, the velocity reduction value of the calculated section does not change significantly.

[0073] S5. Determine the characteristic flow Q to be calculated based on the measured data of the study river section i , must include the lowest navigable water level and the highest navigable water level. Other characteristic flows in between, such as normal water level, can be determined based on the channel regulation needs of the studied river section. Determine the characteristic flow Q based on 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 the typical calculated cross-section before excavation is measured from the cross-sectional topographic map i0 From the cross-sectional topographic map, the characteristic water level ▽Z can be measured and determined.i , Characteristic flow first groove section upper boundary ▽Z 11 The area A enclosed by the typical calculation section i02 .

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

[0076]

[0077] The area A of the typical calculated section after the first and second trenches are excavated under the i-th characteristic flow rate i1 for:

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

[0079] The velocity V of the typical calculation section after the first and second trenches are excavated under the i-th characteristic flow rate i1 for:

[0080]

[0081] The velocity change value △V of the typical calculation section after the first and second trenches are excavated under the i-th characteristic flow rate i for:

[0082]

[0083] In the above formula (10), i is I at the lowest navigable water level, and II at the highest navigable water level. Several characteristic water levels between the lowest and highest navigable water levels are taken for calculation, and i is recorded as III, IV, etc. Assume that the excavation area A of the second trench is 12j (j takes 0, 1, 2...) and changes from small to large. According to formula (1) to formula (10), the velocity change value △V of the typical calculation section after the first trench and the second trench are respectively calculated. ij , the velocity change value of the cross section at the lowest navigable water level is △V I , the velocity change value of the cross section at the highest navigable water level is △V II , the flow velocity change value of the cross section at other characteristic water levels is △V III , △V IV ……. Draw the excavation area A of the second trench as the excavation area of ​​the second trench gradually increases. 12j The velocity change value △V of the typical calculation section ij The relationship curve between them.

[0084] Under the lowest navigable water level of the first working condition (denoted as I), the excavation area A of the second trench is drawn 12j The velocity change value △V of the typical calculation section Ij The relationship curve diagram is as follows: Figure 2 .

[0085] Under the second working condition, at the lowest navigable water level (denoted as II), the excavation area A of the second trench is drawn 12j The velocity change value △V of the typical calculation section IIj The relationship curve diagram is as follows: 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 the normal water level, under the normal water level (denoted as III), the excavation area A of the second trench is drawn. 12j The velocity change value △V of the typical calculation section IIIj The relationship curve diagram is as follows: Figure 4 .

[0087] like Figure 5 The excavation area A of the second trench under each working condition i 12j The velocity change value △V of the typical calculation section ij The relationship curve between A and 12j Increase △V ij The inflection point when the characteristic flow rate is basically unchanged is K i , the corresponding excavation area of ​​the second trench is A 12iK , the velocity change value of the typical calculation section △V iK When comparing different characteristic working conditions i, the excavation area of ​​the second groove corresponding to the inflection point is A 12iK , take the maximum value 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 in the protection scope of the present invention.

Claims

1. A method for excavating a complex cross-section navigation channel in a mountainous area, characterized in that: The following steps are involved: S1. Determine the planned navigation depth H and planned navigation width B of the navigation channel according to the navigation channel planning; S2. Select a narrow section with insufficient water depth as a typical trenching section; S3. Draw a typical calculation cross-section diagram based on typical calculated measured terrain data points; S4. Excavate the first trench section. According to the typical calculation section diagram, determine the centerline point of the channel and the position of the channel edge line, check the water depth under the lowest navigable water level, determine the first trench section, and record the excavation area of ​​the first trench section as A. 11 ; S5. Excavate the second trench section. Assume that the excavation area of ​​the second trench section is A. 12 By assuming that the excavation area of ​​the second trench section is A12 from small to large, the flow velocity reduction value of the typical calculation section is calculated until the flow velocity is reduced to the design requirement.

2. The method for excavating a complex cross-section navigation channel in a mountainous area according to claim 1, characterized in that: According to the cross-sectional topographic map, measure the elevation corresponding to the lowest navigable water level. Measure the boundary elevation of the first trench section Measure the bottom boundary elevation of the first trench section The cross-sectional area between the upper boundary of the first trench section and the original riverbed bottom boundary is A. 01 ; Minimum navigable water level The water level of the first trench section The depth between 02 for: The height h of the first groove section 11 for: h 11 =H-h 02 (2) The bottom boundary width b of the first groove section 12 Taking the designed width of the channel B, we have: b 12 =B (3) Assume that the slope of the first groove section is m, then the upper boundary width b of the first groove section is 11 for: The area of ​​the navigation groove below the upper boundary of the first trench section is: Excavation area A of the first trench section 11 :

3. The method for excavating a complex cross-section navigation channel in a mountainous area according to claim 1, characterized in that: According to the measured data of the river section, determine the characteristic flow Q that needs to be calculated i , must include the lowest navigable water level and the highest navigable water level; Determine characteristic flow Q based on hydrological analysis data i Corresponding characteristic water level Corresponding to the i-th characteristic flow Q i , the corresponding water level is The cross-sectional area A of the typical calculated cross-section before excavation is measured from the cross-sectional topographic map. i0 ; From the cross-sectional topographic map, the characteristic water level can be measured and determined Upper boundary of the first groove section under characteristic flow The area A enclosed by the typical calculation section i02 ; The velocity V of the typical calculation section before excavation under the i-th characteristic flow rate i0 for: The area A of the typical calculated section after the first and second trenches are excavated under the i-th characteristic flow rate i1 for: A i1 =A i02 +A 11 +A 12 (8) The velocity V of the typical calculation section after the first and second trenches are excavated under the i-th characteristic flow rate i1 for: The velocity change value △V of the typical calculation section after the first and second trenches are excavated under the i-th characteristic flow rate i for: In the above formula (10), i is I at the lowest navigable water level, and II at the highest navigable water level. Several characteristic water levels between the lowest and highest navigable water levels are taken for calculation, and i is recorded as III, IV, etc. Assume that the excavation area A of the second trench is 12j (j takes 0, 1, 2...) and changes from small to large. According to formula (1) to formula (10), the velocity change value △V of the typical calculation section after the first trench and the second trench are respectively calculated. ij , the velocity change value of the cross section at the lowest navigable water level is △V I , the velocity change value of the cross section at the highest navigable water level is △V II , the flow velocity change value of the cross section at other characteristic water levels is △V III , △V IV …….

4. The method for excavating a complex cross-section navigation channel in a mountainous area according to claim 3, characterized in that: Draw the excavation area A of the second trench as the excavation area of ​​the second trench gradually increases 12j The velocity change value △V of the typical calculation section ij According to the relationship curve, find the 12j Increase △V ij The inflection point when the characteristic flow rate is basically unchanged is K i , the corresponding excavation area of ​​the second trench is A 12iK , the velocity change value of the typical calculation section △V iK When comparing different characteristic working conditions i, the excavation area of ​​the second groove corresponding to the inflection point is A 12iK , take the maximum value as the excavation area A of the second trench 12 .

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