Construction management practices for hydropower station projects?

Guangzhou Pumped Storage Power Station (hereinafter referred to as Guangzhou Pumped Storage Power Station) is located in Lutian Town, Conghua City, Guangdong Province. It is the first high-head, large-capacity pumped storage power station in my country. The power station was constructed in two phases, with four energy storage units each with a capacity of 300,000 kW installed, with a total installed capacity of 2.4 million kW. It is currently the largest pumped storage power station in the world. The first phase of the Guangzhou Power Station project started on May 25, 1989, and the first unit was put into reliable operation on June 29, 1993. In terms of project construction and management, it has achieved fast progress, good quality, and low investment. It is known as It is known as the “extensive storage model” in the domestic hydropower industry. The second phase of the project started on September 12, 1994. It is planned that the first unit will generate electricity by the end of 1998 and be completed by the end of 1999. At present, the main civil engineering work has been completed and the intense mechanical and electrical equipment installation and commissioning phase has entered. The total budget estimate for the second phase of the project (including delivery of the project and interest during the construction period) is US$263 million and RMB 1.679 billion. Converted based on US$1 = RMB 8.3, the investment per kilowatt is RMB 3,220. Judging from the current situation, the project cost can be controlled within the total estimate. At the same time, the second phase of the project is a step further than the first phase in terms of quality control and safety management, and has won praise from domestic and foreign peers. Such achievements in the construction of the second phase of the project are closely related to the construction management system that implements project legal person responsibility, construction supervision system, bidding and contracting system and other related contents in power station construction management. It is also inseparable from the hard work of the project construction supervision unit. . This article introduces the construction supervision of the second phase of Guangzhou Power Station for reference by colleagues.

1 Clarify the guiding ideology and grasp the key points of the work

According to my country’s national conditions and the characteristics of Guangzhou Storage Power Station, in addition to adhering to the spirit of fair and impartial supervision work, special attention should be paid to the relationship between supervision and assistance. In combination, the supervision work policy of "supervision, management, coordination, assistance, and service" was put forward, forming a guiding ideology for project construction supervision with Guangzhou characteristics. Clarify the responsibilities and scope of work of project supervision. In addition to quality supervision, comprehensive supervision and management of project progress, investment, safety, etc. are also required. At the same time, it is fully recognized that the focus of construction supervision is on site, and it is emphasized that supervisors should often go to the site, supervise key lines or important projects, and promptly discover and coordinate to deal with problems and contradictions in construction.

2 Promote balanced production and promote civilized construction

In the construction of domestic hydropower projects, there is a common phenomenon of rushing for progress and conducting surprise attacks, while not enough attention is paid to balanced production and civilized construction. . There are two main reasons for this: first, the project was launched in a hurry and the construction period was tight; second, it was poor management and inadequate planning, which was loose at first and then tight at the same time. The first phase of the Guangzhou Power Station project has a very tight schedule due to the requirement that the power grid be operated in conjunction with the Daya Bay Nuclear Power Station and put into operation at the same time, and there is no pre-construction preparation work. The second phase of the project was carried out after the completion of the first phase of the project. Preparations for the project construction (internal and external transportation, water supply and power supply, communications, temporary facilities, etc.) are very sufficient. The upper and lower reservoir retaining dams and inlet and outlet projects have been completed. In particular, the power grid has relatively loose requirements on the commissioning time of power plants. Therefore, all parties involved in the project construction seized this favorable factor and put forward the goals of balanced production and civilized construction at the beginning of the project.

2.1 Adhere to seeking truth from facts and determine a reasonable construction period. The first phase of the Guangzhou Storage Power Station project lasted 49 months from the start of construction to the reliable operation of the first unit. Due to the favorable conditions of the second phase of the project, if progress is made at all costs, the construction period should be shorter than that of the first phase, but this may not be the most reasonable. A reasonable construction period must take all factors into consideration and can be determined through repeated calculations and analysis. The main benefit of pumped storage power stations is to meet the peak load regulation needs of the power grid, use the excess power to pump water when the load of the power grid is low, and generate electricity to supplement the lack of power generation capacity of the power grid during peak load times. As for the Guangdong Power Grid, since the first phase of Guangzhou Storage Group has been put into operation, the peak and valley pressure on the power grid is relatively relieved.

In addition, since 1994, the national economy has implemented macro-control and implemented moderately tight financial policies. Guangdong's electricity demand has grown slowly for a period of time, while power supply construction has developed steadily. Therefore, the power grid does not have strict requirements for the start-up date of the second phase of the project. The benefits of putting power generation into production in advance are not significant. On the contrary, excessively shortening the construction period will cause an increase in project investment. The main reasons are as follows: (1) Capital cost Qi plus capital cost refers to the price paid by the enterprise to obtain and use funds, which includes financing expenses and capital use. There are two parts of costs, of which capital costs are the main one. Financing expenses refer to the expenses incurred to obtain funds, such as the expenses paid by an enterprise to obtain a loan. Capital expenses refer to the expenses paid by enterprises for using funds in the process of production, operation and investment, such as loan interest, etc. Therefore, if one-sided pursuit of construction progress will inevitably increase the initial capital investment, it will lead to an increase in loan interest during the construction period. (2) Increased investment in manpower, equipment, and materials. For a project of a certain scale and type, there must be a reasonable amount of labor input. If the actual input amount is greater or less than that, it will lead to an increase in the labor cost of the project. Overemphasis on the high speed of construction will inevitably lead to uneven production, an increase in construction workers during peak periods, and an increase in labor costs. In the same way, more construction equipment is needed during peak periods, which increases the investment in fixed assets to purchase equipment, and after the construction peak period, the equipment will be idle, resulting in an increase in shift costs and entry and exit costs. In addition, due to the large increase in materials required during peak periods, material inventory will inevitably increase. In addition to occupying working capital, it will also increase material losses. (3) Qijia used temporary construction funds due to the increase in construction personnel, equipment and materials during peak periods, and the living and entertainment facilities, office facilities and production facilities on the construction site (such as steel bar processing plants, concrete prefabricated component plants, steel pipe processing plants, etc. ), equipment and material warehouses and storage sites and other temporary facilities will inevitably increase, resulting in an increase in temporary construction costs. On the basis of full demonstration, it was determined that the first unit of the second phase project would generate electricity at the end of 1998. The construction period would be 51.5 months, which was slightly longer than the first phase project and was at a reasonable and advanced level both at home and abroad. As a reasonable construction period was determined, conditions were created for balanced production and construction battles were avoided. Taking the peak construction personnel as an example, there are about 4,000 people in the first phase of the project and about 1,200 in the second phase of the project, which is 70 less than the first phase of the project.

2.2 Promote civilized construction and improve the production environment. In addition to striving for balanced production, the second phase of the project also pays special attention to civilized construction. During the excavation construction, it is necessary to excavate and spray anchors at the same time, and the concrete pavement will be followed at the same time. The working surface in the permanent cavern that cannot be poured with concrete pavement will be leveled at any time. All wind, water, and electricity pipelines used for construction are neatly arranged along the 30-hole wall. The construction site must have smooth drainage, sufficient lighting, and good ventilation. Improved construction conditions, facilitated vehicle traffic, reduced vehicle tire wear, and improved production efficiency. At the same time, it is beneficial to the health of construction workers, and can deal with unsafe factors in a timely manner, eliminate hidden dangers of accidents, and improve the level of safe production. In addition, it also plays an important role in ensuring the safe operation of the Guangzhou Storage Power Plant Phase I and the environmental protection of the energy storage power station as a new tourist attraction.

3 Strengthen contract management and control project costs

3.1 Develop quotation principles and standardize project quotations. Due to the particularity of the second phase of the project, the construction contracting did not adopt competitive bidding, but contracted with the contractor The 14th Engineering Bureau of China Water Conservancy and Hydropower, which is constructing the first phase of the project, exclusively negotiated the bid. In order to ensure the smooth progress of contract negotiations and the effectiveness of investment control, before signing the construction contract contract, a (second-phase project quotation principle) agreement was signed with the construction contractor, which serves as the basis for negotiating the entire project and setting the contract price. The "Quotation Principles" comprehensively stipulates the basis for preparing the quotation for the second phase of the project, the basic unit price (including labor, materials, construction wind, water, electricity, sand and gravel materials), charging standards and price difference adjustment methods, temporary projects and other expenses, etc. The agreement stipulates that the "Quotation Principle" and the contract unit price or the total price of a single project formulated in accordance with the "Quotation Principle" will not be modified or adjusted in any way during the execution of the second-phase contract.

Both parties confirm that: on the premise that Party B fully completes the specified tasks in accordance with the requirements of the contract, they will negotiate and handle the contract performance in a principled spirit of adhering to contract management and seeking truth from facts; neither revising the budget estimate nor making reasonable profits for the construction unit. specific problems that occurred during the period.

3.2 Strictly implement contracts and effectively reduce investment. The second phase of the project pays special attention to contract management. During the contract negotiation stage, in addition to adhering to the spirit of "quotation principle", a reasonable contract price is determined based on the specific conditions of the project. The terms of the contract must be detailed and comprehensive, clarify the rights and responsibilities of both parties, and avoid unclear meanings. Through the efforts of all parties, the contract management of the second-phase project has reached a new level compared to the first-phase project. Both parties A and B can reach a complete understanding of the relevant issues of the contract. Most of the project settlement business is directly negotiated by the contract management departments of each party. It does not have to be solved by the leaders of each unit through unconventional methods, which saves a lot of time and energy and effectively controls the project cost.

3.3 Prepare reports for review and establish supervision prestige. The monthly project progress report of the construction unit must be approved by the supervisor before it can be used as the basis for payment. The project supervision strictly controls the review. Based on the on-site measurement or random test data of the supervisor and the project quantities provided by the construction unit and verified by the supervisor, and in accordance with the relevant provisions of the contract, a comprehensive and careful review is carried out, which not only safeguards the interests of the owner , and improve the prestige of the supervision unit. For projects that have not signed a construction contract or work beyond the scope of the contract, although the project supervisor has the right to decide if the owner's authorized amount is within 200,000 yuan, except for projects with a small workload, the supervisor generally reports to the owner first and Implementation is approved only after consent is obtained, which is very helpful to strengthen communication with the owner. In addition, on the premise of maintaining the contract principles and meeting the design requirements, the project supervision should treat the interests of Party A and Party B fairly and equitably, promote understanding and trust between Party A and Party B, and work together to complete the project construction.

4 Implement comprehensive supervision to ensure project quality

Quality is the life of an enterprise, especially in recent years, quality accidents in domestic construction projects have occurred from time to time. Therefore, ensuring project quality is the focus of construction supervision. Guangzhou Storage Project Supervision adopts a comprehensive and whole-process quality control method in three stages before, during and after the event. Important and key projects, such as underground powerhouse rock wall crane beams, reinforced concrete high-pressure branch pipes, inclined shafts, and tail water For projects such as the tunnel entrance and water outlet earth tunnel sections, the supervision implements an all-weather on-site duty system to track and supervise the entire construction process. Taking the underground factory rock wall crane beam as an example, the main project quality control measures adopted by project supervision are:

4.1 Pre-control Quality control before project construction is the key to ensuring project quality. Before the construction of the rock wall crane beam, the project supervisor strictly reviewed the construction organization design submitted by the construction unit, implemented various construction measures, and strictly reviewed and implemented personnel, equipment, materials, construction technology, construction methods, etc. At the same time, we will work with the construction unit to formulate corresponding emergency measures and solutions to problems that may be encountered during the construction process.

4.2 In-process control Quality supervision during the construction process is the focus of project quality control. In the concrete construction of rock wall crane beams, the main ones include: (l) Warehouse surface acceptance. Before concrete construction, the construction unit must pass the level 3 self-inspection and report to the project supervision for final inspection and approval before concrete can be poured; (2) Check all preparations before opening the warehouse; (3) After concrete pouring begins, supervisors will implement 24-hour on-site tracking and supervision to promptly coordinate and solve problems that arise during the construction process. For example, control the slump of the concrete entering the warehouse, supervise the proper vibration of the concrete, take samples for test pieces according to the specifications, handle the interruption of construction due to special circumstances, etc.; (4) After the concrete pouring is completed, do a good job in concrete maintenance.

4.3 Post-event control When the concrete curing reaches the specified age and the formwork is removed, the project supervisor will go to the site for inspection. The quality of the concrete will be comprehensively evaluated based on the results of on-site sampling tests and visual inspections. If the concrete does not meet the design standards, the construction unit will be required to deal with it.

According to the results of on-site inspection and sampling tests, the concrete of the rock wall crane beam is uniform and dense, with a regular appearance. The concrete strength qualification rate is 100, the guarantee rate is .5, the deviation coefficient Cv=0.16, and the quality is excellent.

5. Progress management to ensure on-schedule power generation for the second phase of the project

Power generation is planned for the end of 1998. The construction period is still tight and requires joint efforts from all parties involved in the project construction. In terms of progress management, project supervision focuses on the following tasks:

5.1 Review and adjustment of the overall project progress plan. Carefully review the overall progress plan reported by the construction unit, paying special attention to the key line engineering projects. Plan and arrange, and propose optimization plans based on actual conditions. When preparing the construction schedule, on the premise of meeting the overall construction period target, try to achieve balanced production and achieve the goal of saving project costs. For example, the installation of the main electromechanical equipment in the factory is scheduled to be carried out after the civil engineering work is basically completed, which is extremely beneficial to reducing the interference between civil engineering and installation construction, accelerating the installation construction progress, and improving the installation quality.

5.2 Decomposition and implementation of the overall project progress plan. Decompose the overall project progress plan into an annual plan, a quarterly plan, a monthly plan and a weekly plan. The weekly plan maintains the monthly plan, and the monthly plan maintains the quarterly plan, and so on. By analogy, check and implement layer by layer. Pay special attention to the planned completion of engineering projects on key lines. If the plan is not completed in a certain month due to special circumstances, measures must be taken to catch up in the next month to ensure the realization of the overall progress plan.

5.3 Create conditions to accelerate the progress of the project. In order to complete the project construction tasks as planned, the project supervisor actively cooperates with the work of the construction unit. In addition to on-site inspection and acceptance on call, we also implement an all-weather tracking and supervision system for key projects so that problems encountered during the construction process can be solved as quickly as possible.

6 Implement safety first and do a good job in safety supervision

The second phase of the Guangzhou Storage Project is mainly an underground project. There are a large number of underground caverns, large cross-sections, long distances, and up and down It is criss-crossed, especially inclined shafts, high-voltage cable tunnels, tailrace pressure regulating well ventilation tunnels and other inclined tunnels and upstream and downstream pressure regulating wells, as well as parts of the tailrace tunnel near the lower reservoir entrance and exit earth tunnel sections, etc., which require high technical requirements and construction It is difficult and the place where accidents are most likely to occur. The project supervision adheres to the policy of "safety first, prevention first" and effectively performs safety work. The main measures are:

6.1 Establish and improve the safety production system. In order to strengthen the leadership of safety work, an engineering committee has been established Establish a production safety leadership group composed of leaders from each unit; the construction unit establishes a three-level safety management organization of operation teams, companies and branches, with full-time safety officers; project supervision is equipped with safety engineers to establish and improve the production safety management system and formulate Rules and regulations with the safety production responsibility system as the core.

6.2 Strengthen safety inspections and make safety forecasts (l) During the excavation and construction of underground projects, a geological forecasting team was specially established, consisting of leaders from relevant units and people with rich experience in underground project construction. It is composed of engineering and technical personnel. By observing and inspecting the geological conditions after excavation, they analyze and predict the stability of surrounding rock, fault alteration zones, loose and dangerous rocks, etc., and provide guiding opinions on dealing with potential accident hazards for relevant parties to make decisions. (2) During the excavation process of the underground powerhouse, a shotcrete anchor support leading group was specially established to go to the site and optimize the shotcrete anchor support design of the factory based on the actual situation after excavation. (3) Do a good job in safe production in key parts and implement a time-limited rectification system for potential safety hazards; strengthen on-site safety coordination; conduct regular or irregular safety inspections; convene regular safety production meetings and carry out safety production evaluation activities to make safety production in-depth People's hearts. All these measures played a big role in the construction of the second phase of the project.

7 Do a good job in design supervision and improve design quality

According to the supervision contract, in addition to construction supervision, the work content of project supervision also includes design supervision. All engineering construction design drawings must be reviewed and stamped by the project supervisor before they become effective, and then distributed to relevant units by the supervisor.

At the same time, the project supervisor is responsible for organizing technical briefings between the design unit and the construction unit in a timely manner and carefully conducting joint review of the drawings. For example, in response to the phenomenon of large vibrations in the underground power plant when the units of the first-phase power station are running, the project supervision team proposed thickening the reinforced concrete floors of each floor of the factory building, and using anchor rods and surrounding rock for the reinforced concrete of each floor of the factory frame in the design of the underground factory building of the second-phase project. Improvement measures such as rigid connections and the use of integral reinforced concrete foundations for ball valves were recognized by the owner and adopted by the design unit.

8 Conclusion

So far, the second phase of the Guangzhou Power Plant has achieved impressive results in terms of investment control, quality assurance, progress management, and safety production. Project supervision He has made a great contribution to this end and has been recognized and appreciated by the owners.

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