JP4194584B2 - Dam construction method - Google Patents

Description

  The present invention generally relates to dam construction methods. In more detail, this invention relates to the construction method of the trapezoid CSG dam and concrete dam which utilize a primary switching temporary waterway as a dam main body.

  Dams that require a flooding (water stoppage) function and high safety are generally constructed so as to extend in the transverse direction of the river. Countermeasures are required. Conventional river flow treatment methods include the temporary drainage tunnel method, the half river deadline method, and the temporary drainage reclamation method, etc., taking into consideration the river flow volume of the target river, topographic geological conditions, dam type, etc. The optimum method is selected with comprehensive consideration of the workability and economic efficiency.

Of these, the temporary drainage tunnel method is a method of excavating a tunnel in the natural slope and switching the river, and has the advantage that the dam body construction can be carried out independently of the river water, but is required for tunnel construction Construction period and construction cost are required separately.
In addition, the Hankawa deadline method is a method in which the river is moved to one side and an open channel (primary channel) is installed, and the main work is divided, and the river is wide and the river flow is large. Although it is adopted when it is extremely uneconomical to adopt the tunnel method or the temporary drainage opening method, there is a problem that the construction period of the dam body generally becomes longer due to the divided construction.
Furthermore, the temporary drainage opening method is a method that installs a simple water channel (primary water channel) using U-shaped grooves, corrugated pipes, etc., and divides the main body construction, and the amount of river water in the target river is small Although it is adopted in some cases, it can be considered as a kind of the Hankawa deadline method.

  In the above-mentioned Hankawa deadline method and temporary drainage opening method, division construction is performed, and therefore, the preceding block requires a temporary drainage channel (secondary channel) in the levee for constructing the subsequent block. Then, after the secondary waterway is completed, the river is switched, and the entire upper part is constructed from the succeeding block and the temporary drainage channel in the bank. The dam temporary drainage channel is closed after the dam is completed and flooding begins. Therefore, in order to flood safely and reliably, facilities such as a closed gate are provided in the levee temporary drainage channel. On the other hand, in low dams with a dam height of less than 15m, there are cases where temporary drainage culverts are installed and the culverts are buried as part of the main body, but in that case, secondary waterways are not required. This is advantageous in terms of the process.

As mentioned above, in low dams with a dam height of less than 15 m, there is an example where temporary drainage is used as part of the main body. However, in dams that are important structures based on the river law, the following 3 For one reason, there are no cases where temporary drainage (primary waterway) was buried.
(1) When a concrete waterway or concrete pipe is installed, it is difficult to secure a permanent and reliable water stop function around the waterway or pipe, and after the dam is completed and flooding is started It is difficult to repair when an abnormality occurs.
(2) A dam is generally provided with a corridor for the purpose of reducing lifting pressure and managing the amount of water leakage, and the altitude of the corridor is near the dam bottom for the purpose of installation. When the primary waterway is buried as a part of the main body, the primary waterway is at an altitude near the riverbed, so there is a possibility that the corridor and the primary waterway may cross each other. In such a case, the corridor must be arranged avoiding the primary waterway, but it is difficult to say that the arrangement is appropriate from the viewpoint of management and function.
(3) The dam must be built on a good bedrock that meets the design conditions. Therefore, when building a dam, the foundation of the dam is determined by conducting geological surveys and evaluation / analysis different from those of other civil engineering structures, but nevertheless there are weak layers such as unexpected faults during excavation. There are many cases where the foundation is changed after being discovered. Therefore, when placing the primary waterway as a part of the main body, it is necessary to perform construction after confirming the condition of the rock in a relatively wide range including the periphery. For this reason, it is customary to install a secondary waterway without using a primary waterway for a main body.

  From the above, in dam construction work, it is usually necessary to switch the river flow to the primary and secondary canals, which divides the construction and contributes to the extension of the construction period. The streamlining of is being hampered.

  The present invention was developed in view of such a situation, and by using the primary switching temporary waterway as a dam body, it is possible to switch the river flow that is normally performed once twice. The purpose is to provide a construction method for the dam.

  The present invention is used for trapezoidal CSG dams and concrete dams (CSG is an abbreviation for Cement Sand and Gravel, hereinafter referred to as “CSG”). Since the trapezoidal CSG dam has a trapezoidal shape, the generated stress is smaller than that of a general concrete dam, and the required performance of the dam foundation rock is also reduced. Therefore, when the trapezoidal CSG dam is used, the above-described problem (3) is solved. Here, CSG is a material formed by mixing locally generated materials such as riverbed gravel and excavated soil with cement. Moreover, even if it is a general concrete dam, it is assumed that the construction method of the present invention is used from the beginning, and if it is judged that the required performance for the foundation rock is satisfied, trapezoidal CSG As with dams, the method of the present invention can be applied.

  The construction method of the trapezoidal CSG dam and the concrete dam according to claim 1 includes a step of excavating a place where a commutation channel is installed, a step of placing a foundation of the commutation channel, and a commutation water on the foundation. Installation of precast members for roads or construction of commutation water channels by cast-in-place concrete, construction of a temporary cutoff on the upstream side of the river, switching the river flow to the commutation water channels, and installation locations of dam dam bodies A step of excavating a portion other than the commutation channel, a step of placing a lower portion of the dam dam body using CSG or concrete, a step of constructing a passage in the dam dam body, CSG or concrete A step of placing the upper portion of the dam dam body using a step, a step of closing the inundation gate at the entrance of the commutation waterway, and a step of constructing an intersection of the commutation waterway and the corridor; Block the commutation channel It is characterized in that comprises a step.

  According to the construction method of the present invention, the above-mentioned problem (1) is solved by using cast-in-place concrete on the upstream side of the commutation water channel in contact with the protective / water-impervious concrete, and at the intersection of the commutation water channel and the passage By constructing the water blocking wall, the above-mentioned problem (2) is solved. Furthermore, in the case of a trapezoidal CSG dam, and in concrete dams, by confirming the required performance of the foundation rock, the above-mentioned problem (3) Therefore, the commutation channel can be used as the dam body, and the construction period can be shortened, the construction cost can be reduced, and the construction can be rationalized.

  Next, a dam construction method according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flow diagram showing a dam construction method according to a preferred embodiment of the present invention, and FIG. 2 is a diagram schematically showing an area where a dam is constructed by the method of the present invention (in FIG. 2). The broken line shows the dam body to be constructed). In this example, a trapezoidal CSG dam and a concrete dam are constructed. Here, the trapezoidal CSG dam refers to a trapezoidal dam constructed using CSG.

  First, the installation location of the commutation waterway is excavated (step 1). In the example shown in FIG. 2, since the slope portion is included in the commutation water channel installation location, the slope portion is also excavated (see FIG. 3). Next, the foundation of the commutation channel is placed (step 2). In addition to normal concrete, CSG may be used for placing the foundation.

  Next, a commutation water channel is constructed by installing a precast member for the commutation water channel or cast-in-place concrete on the foundation (step 3). Thereafter, as shown in FIG. 4, a temporary cutoff part is constructed on the upstream side, and the river flow is switched to the commutation channel (step 4). Thereafter, the cutoff part is constructed on the upstream side and the downstream side.

  Next, a portion other than the commutation channel is excavated among the locations where the dam dam body is installed (step 5). Next, CSG or concrete placement at the lower part of the dam body is performed (step 6).

  Next, a corridor is constructed in the dam body (step 7). The corridor is a passage provided inside the dam body to perform audits after completion of the dam, various measurements, drainage of the dam body and foundation, grout work, gate operation, etc., and is also called an audit gallery. The construction of the corridor may use precast members or a cast-in-place concrete method, but in addition to being able to shorten the construction period, there are advantages such as facilitating the gradual construction of intersections described later. Therefore, the former method is preferable. In general, when a precast member is used to construct a corridor having an inverted U-shaped cross section, the precast member is installed at a predetermined location, and the lower surface portion of the precast member is filled with high-fluidity concrete.

  After constructing the corridor, CSG or concrete placement is performed on the upper part of the dam body (step 8). Thereby, the dam body is completed (see FIG. 5). Next, the inundation gate at the entrance of the commutation channel is closed (step 9). Thereby, the water flow to a commutation waterway is interrupted | blocked.

  Subsequently, construction of the intersection of a commutation waterway and a corridor is performed (process 10). In the construction of the intersection, when the commutation channel is closed, the upstream side of the commutation channel in contact with the protection / water-blocking concrete is cast in place, and the intersection surface is covered with a water blocking wall (for example, steel plate, concrete wall) in advance. . Fig.6 (a) is the schematic diagram which looked at the crossing part of a commutation water channel and a corridor from the upstream. When covering with a still water wall, install a steel plate or a concrete wall in the opening of the corridor where it intersects the commutation channel (see Fig. 6 (b)), and work to close the commutation channel. After going, the water blocking wall is removed, and a precast member of the corridor or a corridor formwork is installed (see FIG. 6C).

  Finally, as shown in FIG. 7, the commutation waterway is closed and the construction of the dam is completed (step 11).

  In addition, in the above-mentioned embodiment, although it explained in connection with construction of a dam provided with a corridor, when not installing a corridor like a small-scale dam, Step 6 in the above-mentioned explanation, 7 and 10 become unnecessary.

  The present invention is not limited to the embodiments of the invention described above, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say, it is something.

It is the flowchart which showed the construction method of this invention. It is the figure which showed typically the area where a dam is constructed by the method of this invention. It is the figure which showed the state which is excavating the installation location of a commutation waterway. It is the figure which showed the state which switched the river flow to the commutation waterway. It is the figure which showed the state which the dam bank body was completed. It is a figure for demonstrating construction of the intersection of a commutation waterway and a corridor. It is the figure which showed the state which closed the commutation water channel and completed the construction of the dam.

Claims (1)

A trapezoidal CSG dam and a concrete dam construction method,
Excavating the location of the commutation channel;
Placing the foundation of the commutation channel;
A step of constructing a commutation water channel by installing a precast member for the commutation water channel on the foundation or cast-in-place concrete;
Constructing a temporary cutoff on the upstream side of the river and switching the river flow to the commutation channel,
A step of excavating a place other than the commutation waterway among the installation places of the dam body,
A process of placing the lower part of the dam body using CSG or concrete;
Building a corridor in the dam body;
A process for placing the upper part of the dam body using CSG or concrete;
Closing the inundation gate at the mouth of the commutation channel;
Performing the construction of the intersection of the commutation waterway and the corridor;
Clogging the commutation channel;
A method comprising the steps of:

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