Supervision of preliminary design of hydropower?

What exactly does the pre-design supervision of hydropower include? Here, Zhong Da Consulting will introduce relevant contents for your reference.

The implementation of the project owner responsibility system inevitably requires strengthening the supervision and management of project design. The design (construction details) management in the engineering construction stage is undertaken by the hired supervision engineer, which has been widely used at home and abroad. At present, some projects in China have implemented the supervision and management of hydropower pre-design (pre-feasibility study, feasibility study and bidding design), but the forms are diverse and the responsibilities are unclear, which needs to be further summarized, deepened and standardized. According to the characteristics of hydropower pre-design, combined with the practice of serving the owner and participating in many engineering evaluation and consultation in recent years, especially the practice of pre-design supervision of Qingjiang Ya Bu Hydropower Station, the forms, responsibilities and conditions of deepening the supervision of hydropower pre-design are preliminarily analyzed.

1 Pre-design supervision is the deepening and development of design supervision form.

1. 1 Pre-design supervision is an effective system to improve the project owner responsibility system.

Design is the soul of engineering construction. Strengthening the supervision and management of design, like the supervision system of engineering construction execution, is an effective system to improve the project owner's responsibility system. Practice has proved that no matter what form of design supervision is adopted for the project, different degrees of effect can be achieved. For example, Baoquan Pumped-storage Power Station in Henan Province adopts the whole process consultation form, and through the cooperation of design and consultation, some complex technical problems (seepage prevention form of upper reservoir, comprehensive utilization, expansion and reinforcement of lower reservoir) have been solved. The pre-design supervision of Shuibuya Hydropower Station in Hubei Province was initially carried out. With the cooperation of the owner, the supervisor and the designer, the pre-feasibility study and the design report of the feasibility study were completed. Under such complicated geological conditions, a large hydropower project with installed capacity of 1 600 MW only took more than five years in two design stages, and the technical scheme of 234 m high concrete face rockfill dam was established. The feasibility report is one year ahead of the power generation period of the pre-feasibility study report, and the hub project is statically invested.

1.2 The preliminary design of hydropower must follow the characteristics of hydropower engineering and its design.

Hydropower projects are strictly limited by natural conditions (climate, hydrology, topography, geology, etc.). ) and social conditions (regional economy, comprehensive utilization, cross-regional development, reservoir flooding, etc. ), and each project is very different. Every project should fully reveal its objective conditions, and survey and design itself is a process of deepening the understanding of objective reality. Therefore, in the process of completing the stage design report, unforeseen factors and changes in survey and design work are inevitable. A correct design can not be produced at the beginning of survey and design work, and can only be completed when the stage design report is put forward. With the experience of engineering analogy, the survey and design work can be optimized, but it is impossible to cross the process of deepening understanding, which is the characteristic and law of the preliminary design of hydropower. There will also be changes in the project construction stage, but unlike the previous design, the changes do not involve big plans, but are only partial.

Design is a knowledge industry, and the quantity and quality of its work are hard to materialize, let alone materialize on time. The quality of knowledge products is often relative, exists in comparison and has great flexibility. This is also very different from the construction work that can be completely materialized in quantity and defined in quality.

As an independent legal person, the design unit has its independence and design autonomy, and is directly responsible for the design results. As an intermediary, design supervision assists the owner to intervene in design management and only undertakes the guarantee or supervision function of completing the design contract. Although the construction technology of contemporary hydropower projects has developed rapidly, there are still some experiences; There are different views on technology, and it is difficult to reach an agreement because of different experiences; On the premise of technical and economic feasibility, different schemes often have their own advantages and disadvantages, and the difference in comprehensive benefits of schemes is sometimes difficult to be absolute, and the schemes are very plastic; The synchronization of supervision and design has a process of deepening understanding; Supervision can't replace design, which determines that the guarantee and supervision functions of early design supervision should be realized by grasping principles, directions, schemes and procedures, which is qualitatively different from the requirements of construction supervision for contractors to construct according to drawings.

From the analysis of the above three aspects, it can be seen that the requirements for the responsibilities of supervision in the early stage of hydropower design cannot be applied to the practices and requirements of supervision in the construction period, and we must follow the characteristics of hydropower projects and the inherent laws of their design, constantly explore and gradually standardize them.

1.3 Pre-design supervision is the deepening and development of design supervision form.

Hydropower pre-design supervision can be summarized into three forms, which are also three stages of development of pre-design supervision. The first form is to only review the results of the design stage. Although this form has a long history, it is often unable to play a supervisory role in the design because it only asks the results without asking the process, and the temporary participation of the reviewers, especially when the actual engineering problems exceed the experience of the reviewers, so it is difficult to accurately grasp the engineering reality in a short time. As early as the planned economy period in the 1960s, the former General Administration of Water Resources and Hydropower Construction, which was in charge of the whole process of water resources and hydropower construction in China (from river planning to engineering construction), summed up the experience and deeply felt that there were disadvantages in this kind of review, and once put forward the requirement of "design review in the design process". In recent years, under the condition of market economy, many projects have been hired by owners to consult the whole process of the preliminary design of hydropower projects, that is, to develop into the second form. The consulting unit began to intervene from discussing the survey and design work outline, and consulted by topic or step by step until the design stage report was completed. The preliminary design supervision of Shuibuya Hydropower Station is the beginning of the third form and the exploration of the deepening and development of the second form. The main difference between whole-process consultation and design supervision is that the former only involves design results, while the latter involves design management; The former only puts forward consulting suggestions, and the latter undertakes the responsibility of assisting the owner to supervise and promote the completion of the design contract.

The pre-design supervision of Shuibuya Hydropower Station has completed the pre-feasibility report and feasibility report stage, and is now in the bidding design stage, which is a pioneering work and needs more engineering practice to summarize and standardize.

2 Preliminary definition of design supervision responsibilities in the early stage of hydropower projects

2. 1 Design quality control

Quality control is the center of design supervision. According to the characteristics of hydropower design, the overall control is mainly carried out through the following points.

2. 1. 1 Grasp the design depth of each stage.

According to the requirements of the design report compilation regulations and current policies at each stage, it is the first step to grasp the design quality and promote the design to achieve appropriate coverage and due depth. This is usually achieved through the survey and design work outline, and adjusted in time during the design process. For example, Shuibuya Hydropower Station has two dam sites for comparison, each with its own advantages and disadvantages, which are complicated and each with its own problems, so it needs scientific and technological research and comprehensive investigation. According to the depth requirements of the design stage, a dam site with overall feasible technical and economic conditions and social environment can be selected as a representative, and after preliminary work, a report can be compiled in the pre-feasibility study stage; In the feasibility report stage, the dam site must be selected first. Although the two dam sites are required to have the same depth, they should have basic conclusions and feasible countermeasures for their respective key technical and economic problems. However, we can learn from the experience of similar projects and choose a realistic and feasible hub layout scheme as a representative for comprehensive comparison and selection. After the dam site is selected, it is necessary to further optimize the implementation of key technologies and complete the feasibility report. The design of Shuibuya Hydropower Station is carried out according to this hierarchical depth requirement, thus speeding up the design process.

2. 1.2 Grasp the demonstration direction of key technologies in each design stage.

According to the purpose and function of each stage of design, we should grasp the technical direction of scheme demonstration, so that every step of work is realistic and reasonable. Before dam selection, Shuibuya dam site was originally planned to be represented by concrete face rockfill dam. However, considering that there was no high dam experience as high as 234 m at home and abroad at that time, the Tianshengqiao first-stage dam had just started construction, so it was impossible to carry out a lot of scientific and technological research in the pre-feasibility study and dam selection stage. It is suggested to learn from international experience and take the earth core rockfill dam as the representative to make the scheme technically feasible. After the site of Shuibuya dam is selected, in view of the economic advantages of concrete face rockfill dam, it is suggested to carry out scientific and technological research to promote the establishment of the dam type. Another example is the plan of two dams (two arch dams over 200 m) and two reservoirs at the dam site of the Half Gorge of Shuibuya Project. In view of the large amount of work in this scheme, it is suggested to adopt the hub scheme of one dam and one reservoir and block the karst leakage in the reservoir area (domestic experience) to participate in the dam site selection.

2. 1.3 Grasp the implementation of key technologies

Grasping the key technologies and implementing them according to the stage requirements is the basis to ensure the design quality. The technical key of Shuibuya core rockfill dam is to determine whether the local gravel soil and weathered soil can meet the seepage control requirements and available reserves. Under the urging of the design director for many times, the survey, design and scientific research units * * * worked together to demonstrate the feasibility of the earth dam core dam technology, which promoted the approval of the pre-feasibility study report. After the dam is selected, the key technical problems of high concrete face rockfill dam (rockfill, concrete face slab and joint water stop) are tackled by the state science and technology, and a conclusive demonstration is made, and a feasible scheme is put forward.

2. 1.4 Actively participate in optimization design.

Constantly optimizing design and increasing scientific and technological content are the signs of high-quality design achievements. In the design process, the design supervisor not only assists the owner in tackling key scientific and technological problems such as high concrete face dam, but also actively participates in design optimization and puts forward optimization suggestions. If the surrounding rock at the bottom of Shuibuya underground powerhouse is soft, simplifying the layout of underground caverns will be beneficial to the stability and simplification of surrounding rock. Therefore, after research, there is no downstream surge shaft, so it is suggested to move the main transformer room to the ground, thus greatly simplifying the underground cavern.

2.2 Design progress control

There are many links in hydropower engineering survey and design (social cooperation, comprehensive utilization, seasonal influence of geological exploration, etc.). ), and there are many professional intersections (survey, design, electromechanical, construction). The factors that affect and change the design process are complex. Strengthening the network management of design can play a regulatory role, but to promote its realization, it is necessary to strengthen technical adjustment and cooperation.

2.2. 1 Distinguish levels and define key points.

According to the requirements of the design stage and the situation of the project, the demonstration and comparison work is divided into several levels, the key points of each level are defined, and the design scope is effectively tightened step by step from surface to point. In view of the fact that the Shuibuya dam site can only use rockfill dam, and the dam line has little change, the left bank is concave, slightly higher than the topography of the dam site platform, and the coastal spillway has good drainage and favorable topographic and geological conditions, it is suggested that the overall layout of the hub should be selected as Grade I.

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