阅读说明：本技术 受限空间水下疏浚与抛泥评估方法 (Confined space underwater dredging and mud throwing evaluation method ) 是由 刘卫 邹丰 冯先导 刘聪聪 王一军 朱映滔 鄂国兴 王鑫 林红星 陈子君 刘春彦 于 2021-10-15 设计创作，主要内容包括：本发明公开了一种受限空间水下疏浚与抛泥评估方法,包括1)疏浚评估,1.1)采集水下数据；1.2)划分开挖断面,拟定初始水位线；1.3)快速计算水下疏浚量；1.4)评估确定超挖或欠挖区域范围及超挖或欠挖工程量。2)抛泥评估,2.1)收集现场工程区域水文、波浪、泥沙和地形数据；2.2)构建二维潮流泥沙数学模型；2.3)模拟分析不同施工时间段、不同抛泥点工况下抛泥回淤的深度与范围；2.4)评估确定最优抛泥点位置。本发明的受限空间水下疏浚快速评估方法能快速计算各断面疏浚量,降低了施工成本,提高了疏浚效率。本发明的抛泥评估方法既确保了受限空间疏浚的施工质量,解决了因抛泥回淤对工程区域造成不利影响的问题。(The invention discloses a method for evaluating underwater dredging and mud throwing of a limited space, which comprises the following steps of 1) dredging evaluation, 1.1) collecting underwater data; 1.2) dividing an excavation section, and drawing up an initial water level line; 1.3) rapidly calculating the underwater dredging amount; 1.4) evaluating and determining the over-digging or under-digging area range and the over-digging or under-digging engineering quantity. 2) Mud throwing evaluation, 2.1) collecting hydrological, wave, sediment and topographic data of the field engineering area; 2.2) constructing a two-dimensional tidal current sediment mathematical model; 2.3) simulating and analyzing the depth and range of mud throwing and back-silting in different construction time periods and under different mud throwing point working conditions; 2.4) evaluating and determining the optimal mud throwing point position. The method for rapidly evaluating the underwater dredging in the limited space can rapidly calculate the dredging amount of each section, reduce the construction cost and improve the dredging efficiency. The mud throwing evaluation method not only ensures the construction quality of the limited space dredging, but also solves the problem of adverse influence on the engineering area caused by mud throwing and back-silting.)

1. A confined space underwater dredging and mud throwing evaluation method is characterized by comprising the following steps:

1) dredging evaluation

1.1) collecting underwater data; using a depth finder in an open area without shielding on the water surface, using a measuring rope in a closed area with a pile foundation in the water and a high pile wharf platform or other building structures at the top for shielding, and respectively acquiring underwater design elevation data, terrain elevation point data before and after excavation and underwater data of a basic scale of a limited space of an engineering;

1.2) dividing an excavation section, and drawing up an initial water level line; dividing the wharf of the excavated area into a plurality of sections S1-Sn according to the longitudinal distance A, and marking the positions of the wharf front platform surface layer, the wharf rear platform surface layer and the prefabricated beam at the top so as to conveniently search the area corresponding to the sections; and (3) planning the positions and the number of elevation points to be measured by combining the section direction with the vicinity of the pile foundation in the limited area, determining the measuring points according to the transverse interval B, and recording the elevation of each measuring point in the section and the position relative to the pile foundation. Calculating an original point O by taking the intersection point of the line in front of the wharf and the section as a calculation original point, taking the distance between a measuring point and the original point in each section as a starting point distance, and drawing a section diagram of the starting point distance and the elevation by combining corresponding elevation data;

1.3) rapidly calculating the underwater dredging amount; dividing excavation sections and mileage according to a dredging area, setting an initial water level line, calculating the area of the water passing sections under the initial water level according to a formula (1) according to the starting point distance, the elevation and the initial water level line of each section, calculating the water storage volume among the sections according to a formula (2), and calculating the dredging amount and the total dredging amount of each section according to the difference of the water storage volume before and after excavation:

A(i)＝DL(i，j)·{Z0-0.5[ZE(i，j+1)+ZE(i，j)]} (1)

wherein A (i) is the area of the section i under the initial water level, DL (i, j) is the distance between two elevation points of j and j +1 in the section i, ZE (i, j) is the terrain elevation of the elevation point j of the section i, and W (i +1) is the water storage volume between the sections i and i +1 under the initial water level. DX (i +1) is the difference between the mileage of the section i and the mileage of the section i + 1;

1.4) evaluating and determining the area range of the over-excavation or under-excavation area and the over-excavation or under-excavation engineering quantity, and guiding on-site accurate dredging; the method comprises the steps of rapidly evaluating the dredging condition between each section and a specific position by calculating the section dredging amount and drawing a terrain change diagram before and after dredging; evaluating and determining the over-excavation or under-excavation area range and the over-excavation or under-excavation engineering quantity by combining the underwater topographic map and the section mark of the wharf superstructure, and guiding construction of underwater inter-pile dredging equipment at the bottom of the wharf surface layer; searching markers near the limited space according to the section, and guiding on-site accurate dredging;

2) evaluation of mud throwing

2.1) collecting hydrological, wave, sediment and topographic data of the field engineering area; selecting a typical point for measuring a construction area by combining the actual construction water area condition, and collecting the hourly tide level, wave process and sand content change process of the typical point;

2.2) constructing a two-dimensional tidal current sediment mathematical model based on a two-dimensional water flow sediment motion equation; firstly, extracting a topographic elevation point, selecting relevant parameters such as roughness, sediment characteristics and the like of a model construction area, inputting a process of changing the sea level and the sediment content time by time as boundary conditions, constructing a two-dimensional tidal current sediment mathematical model, and calibrating and verifying the mathematical model by combining actual measurement sediment data of a field limited space dredging test section;

2.3) simulating and analyzing the mud throwing and silting range and thickness under the working conditions of different tide levels and different mud throwing points; simulating and analyzing the depth and range of mud throwing and back-silting under different construction time periods and different mud throwing point working conditions according to the tide level conditions corresponding to the limited space dredging construction time period by adopting a numerical simulation method;

2.4) evaluating and determining the optimal mud throwing point position to avoid adverse effects caused by mud throwing and back silting; and (4) determining a proper dredging construction time period and a mud throwing point position according to the simulation analysis result of the step 2.3), thereby realizing the effect of reducing the influence of mud throwing and back-silting.

2. The confined space underwater dredging and mud throwing evaluation method according to claim 1, wherein in step 1.2), the longitudinal spacing a is 5-7 m, and the transverse spacing B is 1/2 a.

3. The confined space underwater dredging and mud throwing evaluation method of claim 1, wherein the data is preprocessed according to the excavated sections divided in step 1.2), the starting point distance, the elevation and the mileage interval of each section are extracted, and the dredging amount and the total amount of each section are calculated. Meanwhile, an unstructured grid is divided into an engineering excavation area, the size of the grid is determined according to the precision of the elevation points, the difference between the designed elevation and the excavated elevation is led into the grid and then interpolation is carried out, an underwater topographic map is formed, and the over-excavation or under-excavation condition of each position point is visually displayed visually.

4. The method for evaluating underwater dredging and mud dumping in highly confined space according to claim 1, wherein in step 2.3), data such as field tide, silt and the like are adopted, initial conditions and boundary conditions are set based on a two-dimensional water flow motion equation, a silt continuity equation and a riverbed deformation equation, a finite volume numerical value is adopted for solving, a two-dimensional tide silt mathematical model is constructed and verified, silt motion characteristics of different mud dumping points under different hydrological conditions are simulated, and the influence of the tidal current on desilting thickness and diffusion range of an excavated area within a period of time after mud dumping is calculated.

Technical Field

The invention relates to an underwater dredging and mud-throwing project, in particular to an assessment method before underwater dredging and mud-throwing construction with building structure shielding at the top of a port wharf or a channel, and belongs to the technical field of underwater dredging construction.

Background

The underwater dredging engineering adopts a cutter suction pump or an air suction dredger to excavate underwater silt and carry out transportation treatment, and is mainly applied to excavation of harbor ponds or harbor entering navigation channels and hydraulic filling and land reclamation to build wharfs, harbor areas and harbor facing industrial areas. In recent years, with the continuous expansion of the infrastructure of the water transportation engineering in China, the underwater dredging construction in the water areas with complex hydrological and geological conditions and limited operation space gradually becomes a difficult problem facing the industry.

In the underwater dredging operation process with pile foundations in water and high-pile wharf platform beam plates or other building structures at the top, the underwater dredging excavation state is difficult to evaluate due to limited construction operation space, and underwater over-excavation or under-excavation sometimes occurs. The existing dredging evaluation method mostly calculates the excavation volume according to a complete topographic elevation point, and the data preprocessing is complicated and is not easy to directly guide the site construction. Meanwhile, the mud throwing position after underwater dredging and excavation is usually selected conveniently according to experience and construction, and if the selection is improper, the mud throwing and silting phenomena are easily caused due to the influence of tidal currents and the characteristics of the dredged soil layer.

Disclosure of Invention

The invention aims to provide a method for evaluating underwater dredging and sludge throwing in a limited space, which solves the problems that the underwater dredging construction is difficult to meet the design requirement due to the fact that the sludge digging condition in a limited area is difficult to evaluate and the adverse effect on an engineering area caused by sludge throwing and sludge returning is solved.

The invention is realized by the following technical scheme.

A confined space underwater dredging and mud throwing evaluation method comprises the following steps:

1) dredging evaluation

1.1) collecting underwater data; using a depth finder in an open area without shielding on the water surface, using a measuring rope in a closed area with a pile foundation in the water and a high pile wharf platform or other building structures at the top for shielding, and respectively acquiring underwater design elevation data, terrain elevation point data before and after excavation and engineering limited space basic scale size underwater data;

1.2) dividing an excavation section, and drawing up an initial water level line; dividing the wharf of the excavated area into a plurality of sections S1-Sn according to the longitudinal distance A, and marking the positions of a wharf front platform surface layer, a wharf rear platform surface layer, a prefabricated beam and a cast-in-place beam at the top so as to conveniently search the area corresponding to the sections; and (3) planning the positions and the number of elevation points to be measured by combining the section direction with the vicinity of the pile foundation in the limited area, determining the measuring points according to the transverse interval B, and recording the elevation of each measuring point in the section and the position relative to the pile foundation. Calculating an original point O by taking the intersection point of the line in front of the wharf and the section as a calculation original point, taking the distance between a measuring point and the original point in each section as a starting point distance, and drawing a section diagram of the starting point distance and the elevation by combining corresponding elevation data;

1.3) rapidly calculating the underwater dredging amount; dividing excavation sections and mileage according to a dredging area, setting an initial water level line, calculating the area of the water passing sections under the initial water level according to a formula (1) according to the starting point distance, the elevation and the initial water level line of each section, calculating the water storage volume among the sections according to a formula (2), and calculating the dredging amount and the total dredging amount of each section according to the difference of the water storage volume before and after excavation:

A(i)＝DL(i，j)·{Z0-0.5[ZE(i，j+1)+ZE(i，j)]} (1)

wherein A (i) is the area of the section i under the initial water level, DL (i, j) is the distance between two elevation points of j and j +1 in the section i, ZE (i, j) is the terrain elevation of the elevation point j of the section i, and W (i +1) is the water storage volume between the sections i and i +1 under the initial water level. DX (i +1) is the difference between the mileage of the section i and the mileage of the section i + 1;

1.4) evaluating and determining the area range of the over-excavation or under-excavation area and the over-excavation or under-excavation engineering quantity, and guiding on-site accurate dredging; the method comprises the steps of rapidly evaluating the dredging condition between each section and a specific position by calculating the section dredging amount and drawing a terrain change diagram before and after dredging; evaluating and determining the over-excavation or under-excavation area range and the over-excavation or under-excavation engineering quantity by combining the underwater topographic map and the section mark of the wharf superstructure, and guiding construction of underwater inter-pile dredging equipment at the bottom of the wharf surface layer; searching markers near the limited space according to the section, and guiding on-site accurate dredging;

2) evaluation of mud throwing

2.1) collecting hydrological, wave, sediment and topographic data of the field engineering area; selecting a typical point for measuring a construction area by combining the actual construction water area condition, and collecting the hourly tide level, wave process and sand content change process of the typical point;

2.2) constructing a two-dimensional tidal current sediment mathematical model based on a two-dimensional water flow sediment motion equation; firstly, extracting a topographic elevation point, selecting relevant parameters such as roughness, sediment characteristics and the like of a model construction area, inputting a process of changing the sea level and the sediment content time by time as boundary conditions, constructing a two-dimensional tidal current sediment mathematical model, and calibrating and verifying the mathematical model by combining actual measurement sediment data of a field limited space dredging test section;

2.3) simulating and analyzing the mud throwing and silting range and thickness under the working conditions of different tide levels and different mud throwing points; simulating and analyzing the depth and range of mud throwing and back-silting under different construction time periods and different mud throwing point working conditions according to the tide level conditions corresponding to the limited space dredging construction time period by adopting a numerical simulation method;

2.4) evaluating and determining the optimal mud throwing point position to avoid adverse effects caused by mud throwing and back silting; and (4) determining a proper dredging construction time period and a mud throwing point position according to the simulation analysis result of the step 2.3), thereby realizing the effect of reducing the influence of mud throwing and back-silting.

Further, in the step 1.2), the longitudinal distance a is 5-7 m, and the transverse interval B is 1/2 a.

And further. Preprocessing data according to the excavation sections divided in the step 1.2), extracting the starting point distance, the elevation and the section mileage interval of each section, and calculating the dredging amount and the total amount of each section. Meanwhile, an unstructured grid is divided into an engineering excavation area, the size of the grid is determined according to the precision of the elevation points, the difference between the designed elevation and the excavated elevation is led into the grid and then interpolation is carried out, an underwater topographic map is formed, and the over-excavation or under-excavation condition of each position point is visually displayed visually.

Further, in the step 2.3), data such as field tide, silt and the like are adopted, initial conditions and boundary conditions are set based on a two-dimensional water flow motion equation, a silt continuity equation and a riverbed deformation equation, finite volume numerical value solution is adopted, a two-dimensional tide silt mathematical model is constructed and verified, silt motion characteristics of different mud throwing points under different hydrological conditions are simulated, and influence of tidal current on desilting thickness and a diffusion range of an excavated area within a period of time after mud throwing is calculated.

The method for rapidly evaluating the underwater dredging of the limited space refers to a field object to divide the cross sections, rapidly calculates the dredging amount between the cross sections according to the relative position of the measuring point and the obstacle and the underwater elevation, rapidly evaluates and determines the over-digging area or the under-digging area and the over-digging or the under-digging amount, and searches the over-digging area or the under-digging area according to the field object to carry out construction. The dredging amount of each section can be rapidly calculated, the dredging amount is compared with the designed elevation of the dredging, and an underwater topographic map is drawn. Aiming at the problem that the limited space is difficult to dredge, the over-excavation or under-excavation range and the dredging amount thereof can be visually displayed, and the underwater dredging construction can be accurately guided; meanwhile, the construction cost of personnel, construction machinery and the like which is increased due to the fact that filling or heavy excavation is carried out after overbreak or underexcavation is carried out is reduced, the dredging efficiency is improved, and the problem that the underwater dredging construction cannot meet the design requirements due to the fact that the dredging condition in a limited area is not easy to evaluate is solved.

The method for evaluating the sludge throwing in the limited space calculates the sludge back-silting thickness and range of the sludge throwing to the excavated area under the influence of the tide, and determines the optimal sludge throwing point position, so that the problems that the distance between the sludge throwing and the engineering area is short, the sludge throwing and back-silting are increased, the excavation engineering amount is increased, the sludge conveying pipeline is too long, the pumping cost is increased, and a cross operation situation possibly formed with other construction procedures in a water area is avoided, the construction quality of the sludge dredging in the limited space is ensured, and the problem that the engineering area is adversely affected by the sludge throwing and back-silting is solved.

Advantages and features of the present invention will be illustrated and explained by the following non-restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.

Drawings

FIG. 1 is a flow chart of a confined space underwater dredging and mud dumping assessment method;

FIG. 2 is a plan view of a wharf in a project area;

FIG. 3 is a dock elevation;

FIG. 4 is a sectional view of S1;

FIG. 5 is a diagram of underwater terrain variations;

FIG. 6 is a schematic view of mud removal and back-silting.

Detailed Description

The invention will be further explained with reference to the accompanying drawings and an embodiment of soil dredging construction between piles of a high-pile wharf in a large-scale hydraulic project.

As shown in fig. 2 and 3, the high pile wharf includes a front platform 100 and a rear platform 200, the front platform prefabricated panel 101 is installed on the prefabricated beam 102, the rear platform prefabricated panel 201 is installed on the cast-in-place beam 202, the top of the inter-pile soil construction area of the steel pipe pile 30 and the PHC pile 40 is covered, the inter-pile soil dredging operation space is narrow, and the dredging condition is difficult to evaluate. Meanwhile, after the soil between the piles is excavated, the mud-water mixture is conveyed to the sea side and is influenced by the large tidal range of the area and the soil layer sediment characteristics, and if the position of the mud throwing point is improper, the mud throwing and back-silting are caused to the construction area, so that the construction efficiency is reduced.

As shown in fig. 1, the present embodiment includes the following steps:

1) dredging evaluation

1.1) collecting underwater data, using a depth finder in an open area without shielding on the water surface, using a measuring rope in a closed area with a pile foundation in the water and a high pile wharf platform at the top, and respectively collecting underwater design elevation data, terrain elevation point data before and after excavation and underwater data of a basic scale of a limited space of an engineering.

1.2) dividing an excavation section, drawing up an initial water level line, and rapidly calculating the underwater dredging amount; dividing the wharf of the excavated area into a plurality of sections S1-Sn according to the longitudinal distance A, and marking the positions of the wharf front platform surface layer, the wharf rear platform surface layer, the prefabricated beam 102 and the cast-in-place beam 202 at the top, so as to conveniently search the area corresponding to the sections; and (3) planning the positions and the number of elevation points to be measured by combining the section direction with the vicinity of the pile foundation in the limited area, determining the measuring points according to the transverse interval B, and recording the elevation of each measuring point in the section and the position relative to the pile foundation. And (3) taking the intersection point of the line in front of the wharf and the section as a calculation original point O, taking the distance between a measuring point and the original point in each section as a starting point distance, and drawing a section diagram of the starting point distance and the elevation as shown in the figure 4 by combining corresponding elevation data.

1.3) rapidly calculating the underwater dredging amount, dividing excavation sections and mileage according to dredging areas, setting an initial water level line, calculating the area of the water passing section under the initial water level according to a formula (1) and the initial water level line of each section, calculating the water storage volume between the sections according to a formula (2), and calculating the dredging amount of each section and the total dredging amount of each section according to the difference of the water storage volumes before and after excavation:

A(i)＝DL(i，j)·{Z0-0.5[ZE(i，j+1)+ZE(i，j)]} (1)

wherein A (i) is the area of the section i under the initial water level, DL (i, j) is the distance between two elevation points of j and j +1 in the section i, ZE (i, j) is the terrain elevation of the elevation point j of the section i, and W (i +1) is the water storage volume between the sections i and i +1 under the initial water level. DX (i +1) is the difference between the mileage of the section i and the mileage of the section i + 1.

1.4) evaluating and determining the area range of the over-excavation or under-excavation area and the over-excavation or under-excavation engineering quantity, and guiding on-site accurate dredging; rapidly evaluating the dredging condition between each section and a specific position by calculating the section dredging amount and drawing a terrain change map before and after dredging as shown in FIG. 5; evaluating and determining the over-excavation or under-excavation area range and the over-excavation or under-excavation engineering quantity by combining the underwater topographic map and the section mark of the wharf superstructure, and guiding construction of underwater inter-pile dredging equipment at the bottom of the wharf surface layer; and searching markers near the limited space according to the section, and guiding on-site accurate dredging.

2) Evaluation of mud throwing

2.1) collecting hydrological, wave, sediment and topographic data of the field engineering area, combining the actual construction water area condition, selecting a construction area measurement typical point, and collecting the hourly tide level, wave process and sand content change process of the typical point.

2.2) constructing a two-dimensional tidal current sediment mathematical model based on a two-dimensional water flow sediment motion equation, firstly extracting a terrain elevation point, selecting relevant parameters such as roughness, sediment characteristics and the like of a model construction area, inputting a time-by-time change process of a sea level and a sand content as boundary conditions, constructing the two-dimensional tidal current sediment mathematical model, and calibrating and verifying the mathematical model by combining actual measurement sediment data of a field limited space dredging test section.

And 2.3) simulating and analyzing the sludge throwing and silting ranges and thicknesses under different working conditions of the tide levels and the sludge throwing points, simulating and analyzing the depths and the ranges of the sludge throwing and silting under different working conditions of the construction time periods and the sludge throwing points by adopting a numerical simulation method according to the tide level conditions corresponding to the limited space dredging construction time periods, and drawing a graph 6.

2.4) evaluating and determining the optimal mud throwing point position to avoid adverse effects caused by mud throwing and back silting; and (4) determining a proper dredging construction time period and a mud throwing point position according to the simulation analysis result of the step 2.3), thereby realizing the effect of reducing the influence of mud throwing and back-silting.

Further, in step 1.2), the longitudinal distance a is 6m, and the transverse distance B is 1/2a is 3 m.

And further. Preprocessing data according to the excavation sections divided in the step 1.3), extracting the starting point distance, the elevation and the section mileage interval of each section, and calculating the dredging amount and the total amount of each section. Meanwhile, the engineering excavation area is divided into unstructured grids, the size of the grids is determined according to the precision of the elevation points, the difference between the designed elevation and the excavated elevation is led into the grids, interpolation is carried out, an underwater topography map shown in the figure 5 is formed, and the over-excavation or under-excavation condition of each position point is visually displayed.

Further, in the step 2.3), data such as field tide, silt and the like are adopted, initial conditions and boundary conditions are set based on a two-dimensional water flow motion equation, a silt continuity equation and a riverbed deformation equation, finite volume numerical value solution is adopted, a two-dimensional tide silt mathematical model is constructed and verified, silt motion characteristics of different mud throwing points under different hydrological conditions are simulated, and influence of tidal current on desilting thickness and a diffusion range of an excavated area within a period of time after mud throwing is calculated.

In addition to the above embodiments, the present invention may have other embodiments, and any technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of the claims of the present invention.