The Construction Technology of Inflatable Rubber Dam

With the development of polymer composites, there is a new type of hydraulic structures, which is the inflatable rubber dam belongs to the flexible wall structure. In 1957, the world's first inflatable rubber dam appeared in Los Angeles, the United States, since then widely used all over the world. China also built the first inflatable rubber dam in 1966 and that is the right-door inflatable rubber dam in Beijing. Although the dam bag has been replaced twice in the meantime, it has been operating well so far. Since the 1990s, the technology of inflatable rubber dam has made unprecedented development in our country. At present, there are thousands of giant inflatable rubber dam built in our country, and the construction speed is even at an average speed of 300 inflatable rubber dams per year. Among them, the inflatable rubber dam of Donglan River in Xiaowu Village, linyi City, Shandong Province is the longest inflatable rubber dam in the world, which fully shows that the construction technology of inflatable rubber dam in our country has reached the world advanced level.

a)The Classification and Usage of Inflatable Rubber Dam

Water filled inflatable rubber dam and air filled inflatable rubber dam are the two basic forms, the water filled inflatable rubber dam has a significantly higher water filling and water discharging time because of its unique characteristics. However, both types of inflatable rubber dam are similar in terms of cost. From the composition of the inflatable rubber dam structure, the inflatable rubber dam is mainly composed of the civil part, dam bag and anchors, filling and discharging water (air) facilities and control systems and other components. In operation, we must strictly follow the established program and operational rules and regulations. In particular, attention should be paid to the blasting of inflatable rubber dam, which is often due to the fact that the pressure of filling water or filling air of the inflatable rubber dam is significantly higher than the design pressure.

Among many water conservancy projects, inflatable rubber dam is more suitable for sluice projects with low head and long span. For example, it can be used for the diversion of water from the head of a river, which facilitates the flooding during the flood season and facilitates the water diversion of the canal. It can also be used for landscaping in the center of the city, where inflatable rubber dams can be used to intercept river savings and create artificial lakes. In short, the application of inflatable rubber dam is very wide range.

b)The Advantages of Inflatable Rubber Dam

The reason why the inflatable rubber dam can be developed rapidly in our country is inseparable from a series of advantages of its construction. Through qualitative and quantitative analysis with the sluice gate, we can see:

Table 1: The Analytic Result of Inflatable Rubber Dam and Conventional Gate

①The construction cost of the inflatable rubber dam is low. According to the statistics, the average investment can be reduced by 30% to 70%. ②The construction period is not very long, and most of the inflatable rubber dams can be completed in the year of construction. ③As the inflatable rubber dam has a flexible structure, it can effectively buffer the impact of water, resist earthquakes and so on. It can also be applied to garden projects in urban areas, and has a wide range of applications.

a)Preparations:

The preparatory work of inflatable rubber dam construction mainly involves two aspects, one is civil engineering; the other is the customization of inflatable rubber dam bags.

i.Civil engineering: civil engineers need to ensure the prerequisite for the construction of inflatable rubber dam, civil construction projects are mainly related to the excavation of the related control of excavating foundation ditch and burying and observation of the pipeline.

ii.The customization of dam bag: the customization of dam bags should be more reference to several manufacturers, with carefully analysing their performance and credibility to ensure the quality of dam bags, focusing on checking whether they have the product quality certificate issued by the country and the dam bag quality inspection reports. Before making, we should strictly follow the design of the drawings for the manufacture of dam bag and its bottom gasket,it is necessary to strictly check the size and other information after leaving the factory.

b)Construction Process:

The construction procedures of inflatable rubber dam bag as shown below, these procedures are completed in the premise of the preparatory work:

 

i.Installation inspection: it is necessary to carry out a series of inspection work before the construction of inflatable rubber dam bag installation. Specifically, mainly from the following aspects: 1) Measuring the concrete strength of the building, and compared with the design requirements to see whether it meets the design requirements. 2) The surface of the building that needs to be constructed should not be rough, it is best to keep it smooth. 3) Check the pipeline of filing and drainage to see if it is smooth enough, and it must no leakage of the existence of the phenomenon. 4) Make corresponding markings on the base plate, such as center line and dam axis.

ii.Installing the bottom gasket: the bottom gasket must be manufactured by the factory in strict accordance with the requirements of the design drawings. Before leaving the factory, the dimensions of the gasket must be inspected in strict accordance with the design requirements. The bottom gasket should be installed before installing the inflatable rubber dam bag.

iii.Taking dam bag in place: according to the order of downstream first and upstream later, and finally the shore wall. First installing from the center line of the downstream floor to the left and right sides at the same time, after anchoring the downstream, making the dam bag tape turn to the downstream and installing the aqueduct, and then turning the tape to the upstream, aligned the anchor center line of upstream, installing from the center line of the base plate to the left and right sides at the same time. Anchoring both sides of the wall, the dam bag tape should be hung and smoothed, and anchored from the lower part.

iv.Anchoring the screw platen: anchoring the screw platen can be performed from the following procedure. First of all, pay attention to the flatness, and the head and the tail should be aligned, for where there is uneven, it should be used the rubber sheet to level up. Second, locking nuts. It should be tightened several times when locking the nuts, and carried out water experiment to ensure there is no problem, and tighten the nut again. Third, with the help of tools to ensure that the nut tightening, it is generally used torque wrench, and the bolts are tighten one by one in accordance with the stipulated torsional moment.

v.Installing dam bag: inflatable rubber dam bag installation is the focus of the entire process of construction, before installation, it is necessary to conduct a very comprehensive inspection, the inspection items should include the base plate, backing plate and other parts of dam bag. After the inspection, it should be rinsed with water and dried before laying the base plate, and then installing the water hat. The bottom gasket and the flange gasket should be sandwiched between the inlet flange for the drain pipe and the flange of the water cap, and fixed by the bolt and screw cap. The bottom gasket shall be extended, and the anchorage place around the dam bag installation procedure shall be bored according to the bolt position and installed the anchor bolt, and then the waterproof seal shall be perforated, also be set into the anchor bolt and be laid flatly. The dam bags should transported into the warehouse and unfolded, taking the anchor foot at both ends of dam bag in place, after all the dam bag installation work is completed, the dam bag should be checked carefully before the dam bag can be closed.

vi.Drainage experiment: after the installation of the inflatable rubber dam bag is completed, according to the regulations, the filling and draining test needs to be carried out, so as to inspect the filling management of the dam bag and the quality of the anchor installation.

a)Arrange a full-time inspectors

As can be seen from the construction of the inflatable rubber dam, this important step of inspection always runs through the entire installation process. Therefore, it is necessary to arrange full-time inspectors for inspection. Check the content is not limited to the inflatable rubber dam bag, the dimensions of anchor bolt and others and the dredge situation of pipeline, etc. In the inspection, inspectors should be serious and responsible, the contents of the inspection should be carefully recorded, taking the inspection methods of sub item survey, sampling survey or comprehensive survey. 

b)Comprehensive inspection after installing dam bag

After installing the dam bag, it is necessary to comprehensively inspect. In the absence of retaining conditions, dams should be done dam filling test; if conditions permit, the test should be carried out. The inspection items include the sealing of dam bag and the installation; the situation of embedded components; dam bag appearance observation and deformation observation; the situation of filling and drainage water (gas) facilities the observation system and the situation of pressure drop in inflatable dam bag.

c)Strict construction organization

In the construction of inflatable rubber dam, it is necessary to pay attention to the construction organization, and each process are strictly controlled through the construction organization. Inflatable rubber dam installation and construction workers should undergo the strict on-the-job training, the implementation of quality and safety control measures to further improve the quality of the project and to protect the duration of the project.

Although the construction technology of inflatable rubber dam has achieved rapid development in our country, there is still a certain distance from the developed countries on the technology level. Therefore, it is necessary to increase the investment of science and technology in the research of inflatable rubber dam construction technology and formulate the national standards and norms of inflatable rubber dam construction and improve the appropriate quality assurance system.