Method for constructing open-cut river-crossing pipe culvert

Abstract

The application provides a pipe culvert open cut construction method. The method comprises the following steps: inserting and driving a detachable steel sheet pile in the middle of a river construction area, and sequentially performing pipe culvert structure construction on both sides of the river construction area to complete the construction of the pipe culvert crossing the river. The application flexibly performs water isolation treatment through the detachable steel sheet pile, creates a water-free and safe construction environment, realizes segmented construction on both sides of the river construction area, and reduces the influence on the river and river navigation.

Description

Technical Field

[0001] This application relates to the field of water conservancy engineering technology, and in particular to a method for open-cut construction of culverts crossing rivers. Background Technology

[0002] In current urban construction and transportation development, rivers, as natural geographical barriers, often require the construction of crossings to facilitate convenient transportation between their banks. The main construction methods for river-crossing passages are bridges over rivers and tunnels under them. Among these, cut-and-cover construction is a relatively common method for tunnels under rivers. However, this method faces numerous challenges and problems in practice.

[0003] Open-cut construction refers to excavating the bottom of a river to directly construct a tunnel structure. During construction, it is often necessary to cut off the river's flow. However, this direct cut-off construction blocks the river's navigation channel, preventing ships from passing normally. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a method for open-cut construction of culverts across rivers, in order to solve the problem that existing construction methods would affect the normal use of the original river channel.

[0005] To achieve the above and other related objectives, the first aspect of this application provides a method for open-cut construction of a culvert across a river, comprising: driving detachable sheet piles in the middle of a river construction area; wherein the detachable sheet piles include a detachably connected lower sheet pile and an upper sheet pile; setting up a first retaining structure on the left side of the river construction area, the first retaining structure and the detachable sheet piles forming a first cofferdam; draining the first cofferdam and, after drainage, constructing a first section of the culvert structure within the first cofferdam; and, after the first section of the culvert structure is completed, constructing a culvert near the first section of the culvert structure. A water-blocking structure is installed at one end of the detachable sheet piles; the first enclosure structure on the left side of the water-blocking structure is removed, and a second enclosure structure is installed on the right side of the river construction area. The second enclosure structure, together with the remaining portion of the first enclosure structure and the water-blocking structure, forms a second cofferdam; the second cofferdam is drained and the upper sheet piles of the detachable sheet piles within the second cofferdam are removed, while the lower sheet piles are retained to prevent bottom seepage. The second culvert structure is then constructed within the second cofferdam, connecting the first and second culvert structures; the second cofferdam is then removed, completing the construction of the river-crossing culvert.

[0006] In some embodiments of the first aspect of this application, the detachable connection between the lower sheet pile and the upper sheet pile is higher than the expected position of the culvert bottom plate.

[0007] In some embodiments of the first aspect of this application, a first support structure is erected above the water surface in the first cofferdam before the first cofferdam is drained; wherein the first support structure is composed of a plurality of first support walers arranged in parallel along a straight line; the two ends of each first support waler are respectively fixed to opposite sides of the first enclosure structure.

[0008] In some embodiments of the first aspect of this application, the construction of the first culvert structure within the first cofferdam includes: when excavation in the first cofferdam reaches the expected culvert bottom plate position, pouring the bottom plate of the first culvert structure at the culvert bottom plate position; and continuing to construct the first culvert structure upwards after the pouring is completed until the top plate of the first culvert structure is completed.

[0009] In some embodiments of the first aspect of this application, while the first cofferdam is being drained, one or more second support structures are erected at a designated erection location below the first support structure; wherein each second support structure is composed of multiple second support walers arranged in a straight line; while the first culvert structure is being constructed upwards, the second support structures are being gradually dismantled.

[0010] In some embodiments of the first aspect of this application, while constructing the first culvert section upwards, a concrete retaining wall is constructed at the trench position at one end of the first culvert section near the detachable sheet pile; a water-blocking structure is provided at the end of the first culvert section near the detachable sheet pile, including: filling sandbags and geotextile in the following areas to form a water-blocking structure: filling sandbags and geotextile in the following areas to form a water-blocking structure: the area between the concrete retaining wall and the detachable sheet pile, and the area between the concrete retaining wall and the detachable sheet pile and located above the top plate of the first culvert section.

[0011] In some embodiments of the first aspect of this application, a third support structure is erected above the river surface in the second cofferdam before the second cofferdam is drained; wherein the third support structure is composed of a plurality of third support walers arranged in a straight line; and the two ends of each third support waler are respectively fixed to opposite sides of the second cofferdam structure.

[0012] In some embodiments of the first aspect of this application, the construction of the second culvert structure within the second cofferdam includes: when excavation in the second cofferdam reaches the expected culvert bottom plate position, pouring the bottom plate of the second culvert structure at the culvert bottom plate position; and continuing to construct the second culvert structure upwards after the pouring is completed until the top plate of the second culvert structure is completed.

[0013] In some embodiments of the first aspect of this application, while draining the second cofferdam, one or more fourth support structures are erected at designated erection positions below the third support structure; wherein each fourth support structure consists of multiple fourth support walers arranged in a straight line; while constructing the second culvert structure upwards, the fourth support structures are gradually dismantled.

[0014] In some embodiments of the first aspect of this application, the method further includes: dismantling the second cofferdam, simultaneously clearing the water-blocking structure, and completing the construction of the river-crossing culvert.

[0015] As described above, the open-cut construction method for river-crossing culverts in this application has the following beneficial effects:

[0016] This application utilizes detachable sheet piles for flexible waterproofing, creating a waterless and safe construction environment. It enables segmented construction on both sides of the river construction area, reducing the impact on the river and navigation. Attached Figure Description

[0017] Figure 1 The diagram shown is a flowchart illustrating the open-cut construction method for a culvert crossing a river according to one embodiment of this application.

[0018] Figure 2 The diagram shown is a schematic representation of the first cofferdam in one embodiment of this application.

[0019] Figure 3 The diagram shown is a structural schematic of a detachable sheet pile according to an embodiment of this application.

[0020] Figure 4 The diagram shown is a structural schematic of the connection end of the upper sheet pile and the lower sheet pile in one embodiment of this application.

[0021] Figure 5 The diagram shown is a schematic representation of the erection of the first support structure in one embodiment of this application.

[0022] Figure 6 Displayed as Figure 5 A schematic diagram of the AA direction.

[0023] Figure 7 The diagram shown is a schematic representation of the erection of the second support structure in one embodiment of this application.

[0024] Figure 8 The diagram shows the location of the concrete retaining wall in one embodiment of this application.

[0025] Figure 9 Displayed as Figure 8 A schematic diagram of the BB direction.

[0026] Figure 10The diagram shown is a schematic representation of the filled area in one embodiment of this application.

[0027] Figure 11 Displayed as Figure 10 A schematic diagram of the CC direction.

[0028] Figure 12 Displayed as Figure 10 A schematic diagram of the DD direction.

[0029] Figure 13 The diagram shown is a schematic representation of the first cofferdam after its removal in one embodiment of this application.

[0030] Figure 14 The diagram shown is a schematic representation of the second cofferdam in one embodiment of this application.

[0031] Figure 15 The diagram shown is a schematic representation of the erection of the third support structure in one embodiment of this application.

[0032] Figure 16 Displayed as Figure 15 A schematic diagram of the EE direction.

[0033] Figure 17 The diagram shown is a schematic diagram of the upper sheet piles after they have been removed in one embodiment of this application.

[0034] Figure 18 This is a schematic diagram of the river channel after the removal of the remaining first cofferdam, second cofferdam, and water-blocking structure in one embodiment of this application.

[0035] Figure 19 Displayed as Figure 18 A schematic diagram of the GG direction.

[0036] Figure 20 Displayed as Figure 18 A schematic diagram of the HH direction. Detailed Implementation

[0037] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.

[0038] In the embodiments of this application, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" do not necessarily imply that they are different.

[0039] It should be noted that, in the embodiments of this application, the words "exemplary" or "for example" indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0040] In this application embodiment, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0041] To facilitate understanding of the embodiments of this application, firstly, in conjunction with Figure 1 Detailed explanation. Figure 1 This document illustrates a flowchart of an open-cut culvert construction method for crossing a river, as described in an embodiment of the present invention. The open-cut culvert construction method for crossing a river in this embodiment mainly includes the following steps:

[0042] Step S11: Drive detachable steel sheet piles in the middle of the river construction area.

[0043] Specifically, such as Figure 2 As shown, the river channel construction area was determined, and detachable steel sheet piles 1 were driven into the middle of the river channel construction area. At the same time, a corresponding temporary construction platform was erected on the left side of the river channel construction area for subsequent culvert construction.

[0044] It should be understood that the corresponding construction area can be determined in the corresponding river channel according to the actual culvert construction needs, and this invention does not limit this.

[0045] In one embodiment, such as Figure 3 as well as Figure 4As shown, the detachable sheet pile includes: a detachably connected lower sheet pile and an upper sheet pile; both the upper and lower sheet piles are composed of multiple arc-shaped sheet piles connected by a locking structure; the locking structure can be a two-way locking or a four-way locking; the connecting ends of both the upper and lower sheet piles are fitted with flanges; multiple bolt holes are provided on the flanges; each bolt hole is equipped with a matching bolt; the bolts pass through the bolt holes to connect the connecting ends of the upper and lower sheet piles; when the connecting ends of the upper and lower sheet piles are connected, a water-stop rubber gasket is also sandwiched between the flanges of the connecting ends of the upper and lower sheet piles. The part where the connecting ends of the upper and lower sheet piles are connected is the detachable connection point between the lower and upper sheet piles.

[0046] In one embodiment, the detachable connection between the lower and upper sheet piles is higher than the expected culvert bottom slab position. It should be understood that, generally, the detachable connection between the lower and upper sheet piles is 100mm higher than the expected culvert bottom slab position. The culvert bottom slab position can be determined according to the actual culvert construction requirements, and this invention does not limit this.

[0047] Step S12: Set up a first enclosure structure on the left side of the river construction area. The first enclosure structure and the detachable steel sheet piles form a first cofferdam.

[0048] Specifically, such as Figure 2 As shown, the first enclosure structure 2 consists of a first sheet pile structure 21, a second sheet pile structure 22, and a third sheet pile structure 23. Each of these structures is composed of multiple interconnected sheet piles. The first sheet pile structure 21 and the third sheet pile structure 23 are connected to detachable sheet piles 1, and the second sheet pile structure 22 is connected to both the first sheet pile structure 21 and the third sheet pile structure 23. The first sheet pile structure 21 and the third sheet pile structure 23 are located on opposite sides of the first enclosure structure 2. After the first cofferdam is completed, navigation is suspended in the left-hand river construction area, while navigation remains open in the right-hand river construction area.

[0049] Step S13: Drain the first cofferdam and then construct the first culvert section within the first cofferdam. After the first culvert section is constructed, a water-blocking structure is installed at the end of the first culvert section near the detachable sheet pile.

[0050] Specifically, such as Figure 5 As shown, after the first cofferdam is constructed, the first support structure 3 is erected above the initial water level within the first cofferdam. (See diagram) Figure 5 as well as Figure 6As shown, the first support structure 3 includes multiple first support walers 31 arranged in parallel along a straight line. Each first support waler 31 is fixed at both ends to a first sheet pile structure 21 and a third sheet pile structure 23, respectively. It should be understood that the function of the walers is to form a whole with the first cofferdam, jointly resisting lateral forces such as external earth pressure and water pressure, and preventing the foundation pit from collapsing due to local deformation.

[0051] Furthermore, such as Figure 7 As shown, drainage is carried out layer by layer. During the layer-by-layer drainage process, one or more second support structures 4 are erected at the designed locations. The one or more second support structures 4 are all located below the first support structure 3 and are erected sequentially from top to bottom (only one second support structure 4 is shown in the figure). After the drainage meets the requirements, the soil excavation begins until the expected culvert bottom slab position is reached. The designed location of each second support structure can be specified according to actual needs, and this embodiment does not limit this. Each second support structure includes multiple second support walers arranged in parallel along a straight line (the arrangement of the second support walers is the same as that of the first support walers, and the structure of the second support walers is the same as that of the first support walers). The two ends of each second support waler are fixed to the first sheet pile structure 21 and the third sheet pile structure 23, respectively.

[0052] Furthermore, such as Figure 8 as well as Figure 9 As shown, when excavation in the first cofferdam reaches the expected culvert bottom slab position, the bottom slab 51 of the first culvert structure is poured at the culvert bottom slab position. After the bottom slab 51 of the first culvert structure is poured and reaches the design strength, the main body 52 and the top slab 53 of the first culvert structure are constructed layer by layer upwards, and the second support structures 4 are gradually removed until the top slab 53 of the first culvert structure is completed. While continuing to construct the first culvert structure upwards, a concrete retaining wall 6 is constructed at the trench position near the end of the first culvert structure close to the detachable sheet piles. The trench positions include the first trench position located on one side of the main body 52 of the first culvert structure and the second trench position located on the other side of the main body 52 of the first culvert structure. Generally, the first trench position and the second trench position are both 4 to 6 meters away from the detachable sheet piles. It should be understood that the trench refers to the extra trench excavated outside the designed foundation, exceeding the size of the structure itself, to meet the construction operation space requirements of the underground project.

[0053] Furthermore, such as Figure 10 , Figure 11 as well as Figure 12As shown, after the first culvert section is completed, sandbags are filled and geotextile is laid in the following areas to form a water-blocking structure: area F1 between one concrete retaining wall 6 and the removable sheet pile 1; area F2 between another concrete retaining wall 6 and the removable sheet pile 1; and area F3 between the two concrete retaining walls and the removable sheet pile 1, located above the top slab of the first culvert section. It should be noted that the sandbags and geotextile filled in area F3 above the top slab of the first culvert section must be higher than the river surface.

[0054] Furthermore, after the water-blocking structure is completed, the first supporting structure is removed.

[0055] Step S14: Remove the first enclosure structure on the left side of the water-blocking structure, and at the same time set up a second enclosure structure on the right side of the river construction area. The second enclosure structure, together with the remaining part of the first enclosure structure and the water-blocking structure, form a second cofferdam.

[0056] Specifically, such as Figure 13 As shown, the first enclosure structure on the left side of concrete retaining wall 6 is removed. Navigation is restored on the left side of concrete retaining wall 6. The water-blocking structure is used to prevent river water on the left side of concrete retaining wall 6 from entering the second cofferdam. After this, as... Figure 14 As shown, a second enclosure structure 7 is installed on the right side of the river construction area to form a second cofferdam together with the remaining portion of the first enclosure structure and the water-blocking structure.

[0057] Specifically, such as Figure 14 As shown, the second cofferdam structure 7 consists of a fourth sheet pile structure 71, a fifth sheet pile structure 72, and a sixth sheet pile structure 73. Each of these structures is composed of multiple interconnected sheet piles. The fourth sheet pile structure 71 is connected to the remaining first sheet pile structure 21, and the sixth sheet pile structure 73 is connected to the remaining third sheet pile structure 23. Both the fourth and sixth sheet pile structures are connected to detachable sheet piles 1, and the fifth sheet pile structure 72 is connected to both the fourth and sixth sheet pile structures 71 and 73, respectively. The fourth and sixth sheet pile structures 71 and 73 form opposite sides of the second cofferdam structure 7. After the second cofferdam is completed, navigation is permitted in the right-hand river construction area, while navigation is prohibited in the left-hand river construction area.

[0058] Step S14: Drain the second cofferdam and remove the upper sheet piles of the detachable sheet piles inside the second cofferdam, leaving the lower sheet piles to prevent water seepage at the bottom. Then, construct the second culvert structure inside the second cofferdam, while connecting the first culvert structure and the second culvert structure.

[0059] Specifically, such as Figure 15As shown, after the second cofferdam is constructed, a third support structure 8 is erected above the initial water level within the second cofferdam. Figure 15 as well as Figure 16 As shown, the third support structure includes multiple third support walers 81 arranged side-by-side along a straight line. Each third support waler 81 is fixed at both ends to the fourth sheet pile structure 71 and the sixth sheet pile structure 73, respectively. It should be understood that the function of the third support walers here is the same as that of the first support walers described above. Furthermore, the structure of the third support walers is also the same as that of the first and second support walers.

[0060] Furthermore, such as Figure 16 As shown, drainage is carried out layer by layer. During the layer-by-layer drainage process, one or more fourth support structures 9 are erected at the designed locations. These fourth support structures 9 are all located below the third support structure 8 and are erected sequentially from top to bottom (only one fourth support structure 9 is shown in the figure). After the drainage meets the requirements, the soil excavation begins until the expected culvert bottom plate position is reached (the same elevation as the culvert bottom plate position mentioned above). The designed position of each fourth support structure can be specified according to actual needs, and this embodiment does not limit this. Each fourth support structure includes multiple fourth support walers arranged in parallel along a straight line (the arrangement of the fourth support walers is the same as that of the third support walers, and the structure of the fourth support walers is also the same as that of the third support walers). The two ends of each fourth support waler are fixed to the fourth sheet pile structure 71 and the sixth sheet pile structure 73, respectively.

[0061] Furthermore, such as Figure 16 As shown, when excavation in the second cofferdam reaches the expected culvert bottom slab position, the bottom slab 101 of the second culvert structure is poured at the culvert bottom slab position. After the bottom slab 101 of the second culvert structure is poured and reaches its design strength, the upper sheet piles of the detachable sheet piles 1 are removed, and the post-pouring strip is poured at the sheet pile location, connecting the bottom slab 51 of the first culvert structure and the bottom slab 101 of the second culvert structure. After this, the main body 102 and the top slab 103 of the second culvert structure are constructed upwards, and the fourth support structures 9 and the third support structures 8 are gradually removed until the top slab 103 of the second culvert structure is completed. Simultaneously, the first and second culvert structures are connected. The connected state is as follows. Figure 17 As shown. It should be understood that a post-cast strip is a temporary construction joint set up in building construction to solve problems such as temperature shrinkage and settlement differences in concrete structures. It is usually sealed by pouring concrete later in the structural construction process, so that the structure becomes a whole.

[0062] Step S15: Dismantle the second cofferdam and complete the construction of the culvert across the river.

[0063] Specifically, such as Figures 18 to 20 As shown, the second cofferdam was dismantled, and the aforementioned water-blocking structure was cleared to complete the construction of the culvert across the river. The aforementioned post-cast strip is as follows... Figure 19 As shown.

[0064] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0065] In summary, this application provides a method for open-cut construction of a culvert crossing a river. The method includes: driving detachable steel sheet piles in the middle of the river construction area, and then constructing the culvert structure sequentially on both sides of the river construction area to complete the culvert construction. This application utilizes detachable steel sheet piles for flexible water-stopping, creating a waterless and safe construction environment, and enabling segmented construction on both sides of the river construction area, reducing the impact on the river and navigation. Therefore, this application effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0066] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A method for open-cut construction of a culvert crossing a river, characterized in that, include: Detachable sheet piles are driven into the middle of the river construction area; wherein, the detachable sheet piles include a lower sheet pile and an upper sheet pile that are detachably connected. A first enclosure structure is set up on the left side of the river construction area, and the first enclosure structure and the detachable steel sheet piles form a first cofferdam. The first cofferdam is drained, and after the drainage, the first section of the culvert structure is constructed within the first cofferdam. After the first section of the culvert structure is completed, a water-blocking structure is set at the end of the first section of the culvert structure near the detachable steel sheet pile. The first enclosure structure on the left side of the water-blocking structure is dismantled, and a second enclosure structure is set up on the right side of the river construction area. The second enclosure structure, together with the remaining part of the first enclosure structure and the water-blocking structure, forms a second cofferdam. The second cofferdam is drained and the upper steel sheet piles of the detachable steel sheet piles inside the second cofferdam are removed, while the lower steel sheet piles are retained to prevent water seepage at the bottom. Then, the second section of the pipe culvert structure is constructed inside the second cofferdam, while connecting the first section of the pipe culvert structure and the second section of the pipe culvert structure. The second cofferdam was dismantled, and the culvert for crossing the river was completed.

2. The method for open-cut construction of culverts across rivers according to claim 1, characterized in that, The detachable connection between the lower sheet pile and the upper sheet pile is higher than the expected position of the culvert bottom plate.

3. The open-cut construction method for river-crossing culverts according to claim 1, characterized in that, Before the first cofferdam is drained, a first support structure is erected above the water surface in the first cofferdam; wherein, the first support structure is composed of a plurality of first support walers arranged in parallel along a straight line; the two ends of each first support waler are respectively fixed to the opposite sides of the first enclosure structure.

4. The open-cut construction method for river-crossing culverts according to claim 3, characterized in that, Construction of the first culvert section within the first cofferdam includes: When the excavation in the first cofferdam reaches the expected position of the culvert bottom plate, the bottom plate of the first section of the culvert structure is poured at the position of the culvert bottom plate. After the pouring is completed, continue construction of the first section of the culvert structure upwards until the top slab of the first section of the culvert structure is completed.

5. The open-cut construction method for culverts crossing rivers according to claim 4, characterized in that, While draining the first cofferdam, one or more second support structures are erected at designated locations below the first support structure; each second support structure consists of multiple second support walers arranged in a straight line; while constructing the first culvert structure upwards, the second support structures are gradually dismantled.

6. The open-cut construction method for culverts crossing rivers according to claim 4, characterized in that, While constructing the first section of the culvert structure upwards, a concrete retaining wall is constructed at the trench position of the first section of the culvert structure near the detachable sheet pile. A water-blocking structure is provided at one end of the first culvert structure near the detachable sheet pile, including filling sandbags and geotextile in the following areas to form a water-blocking structure: the area between the concrete retaining wall and the detachable sheet pile, and the area between the concrete retaining wall and the detachable sheet pile and located above the top plate of the first culvert structure.

7. The open-cut construction method for culverts crossing rivers according to claim 1, characterized in that, Before the second cofferdam drains water, a third support structure is erected above the river surface in the second cofferdam; wherein, the third support structure is composed of multiple third support walers arranged in a straight line; the two ends of each third support waler are respectively fixed to the opposite sides of the second cofferdam structure.

8. The open-cut construction method for culverts crossing rivers according to claim 7, characterized in that, Construction of the second culvert structure within the second cofferdam includes: When the excavation in the second cofferdam reaches the expected position of the culvert bottom plate, the bottom plate of the second culvert structure is poured at the position of the culvert bottom plate. After the first section of the culvert is poured, construction continues upwards to the second section until the top slab of the second section is completed.

9. The open-cut construction method for culverts crossing rivers according to claim 8, characterized in that, While draining the second cofferdam, one or more fourth support structures are erected at designated locations below the third support structure; each fourth support structure consists of multiple fourth support walers arranged in a straight line; while constructing the second culvert structure upwards, the fourth support structures are gradually dismantled.

10. The open-cut construction method for river-crossing culverts according to claim 1, characterized in that, The method also includes: dismantling the second cofferdam, clearing the water-blocking structure, and completing the construction of the river-crossing culvert.

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