Sankeng Reservoir was built in 1959. The earth dam is 29.5 meters high, 550 meters long, with a catchment area of 38km2 and a storage capacity of 9.62 million m3, and irrigated farmland 1587hm2. As the water supply source of quicksand in the county, it has both power generation benefits. Subsequently, according to the once-in-a-thousand-year standard, the supporting facilities were improved, the dam was reinforced, and the earth dam was raised by 3m, so that the storage capacity was increased to 654.38+0468 million m3, and the benefits were more remarkable. However, the Da Nanshan area where the reservoir is located is one of the four major rainstorm areas in the province, and the flood disaster is impermanent, so the reservoir failed to play a greater role in retaining and storing floods. Therefore, 1980 built a 1 regulating reservoir at the tail of the upstream reservoir, with a total storage capacity of16.5 million m3 and a catchment area of 24.8km2, which greatly reduced the flood control pressure of the downstream reservoir. The maximum dam height of the earth dam of this reservoir is 55 meters, which is the highest in the county, and the dam length is 280 meters. The main function of the reservoir is to store flood and control waterlogging, stagger the flood peaks of Sankeng Reservoir to generate electricity, and discharge the tail water into the lower reservoir, so that the water resources can be fully and comprehensively developed and utilized to supplement the urban water supply source. After the completion of the upper reservoir dam, serious leakage and piping diseases appeared, which threatened the safety of the upper and lower reservoirs at the same time. In order to ensure safety, on the one hand, the storage capacity of the upper reservoir is limited, on the other hand, hidden dangers are identified by means of investigation and geophysical exploration, and the dam is filled and grouted for three times. However, these reinforcement measures failed to eliminate the hidden danger of the dam, and the danger still exists. Such a reservoir, which was operated with disease and failed to exert its maximum storage function, was identified by the expert group of the provincial water administrative department and included in the key infrastructure projects. In view of the fact that filling grouting can't eliminate hidden dangers, the construction design adopts the effective split grouting construction technology of Shenzhen Reservoir and Yunfu Chaoyang Reservoir in the province, and adopts a set of grouting quality automatic monitoring system in the construction process to implement scientific management of grouting construction. Because split grouting is mostly used to reinforce key medium-sized reservoirs in the province, it has achieved good results and become an economical and effective new technology to deal with hidden dangers of earth dams. Through the experience summarized in practice, the splitting grouting has obvious effects on solving the following six hidden dangers: (1) the loose earth dam has poor compaction and poor compactness; There are leakage channels, soft layers, too high saturation line, wet areas or "cowhide swelling" or seepage failure (piping, soil flow) on the dam slope; Dam cracks caused by uneven settlement (excluding landslide cracks); Earth dams built by stages have weak zones and permeable layers at the layers and joints; Dam and other buildings (such as drainage culverts, sluice walls, etc.). ) poor connection, cracks and contact erosion; There are hidden dangers such as biological caves and rotten roots in the dam. Compared with the actual situation of Sankeng Shangku Dam, there are many similarities with these summarized phenomena. The automatic quality monitoring system can monitor the construction process regularly and quantitatively, thus ensuring the effective supervision of the project quality. It can not only change the grouting construction from experience management and quality inspection and supervision after construction to scientific quantitative management and real-time quality inspection and supervision, but also monitor and record the grouting orifice pressure, slurry concentration, grouting flow, grouting quantity and time in real time. The monitoring system can establish a data chart program for analyzing mathematical models, analyze and process the obtained data, check the grouting pressure, grouting quantity, grouting time and wall-forming area, grouting time control and wall-forming efficiency in time, realize the guidance and supervision of grouting process, and automatically generate four monitoring reports of grouting process hole by hole: grouting depth ~ grouting quantity, grouting time ~ grouting quantity and orifice pressure. In this way, we can grasp all kinds of situations in the whole grouting construction process in time. Due to the improvement of grouting construction technology (dam splitting grouting, curtain grouting at two dam ends and curtain grouting at dam foundation) and the adoption of automatic monitoring of grouting process in construction quality management, good results have been achieved. After the completion of reservoir reinforcement, after four years of normal operation and high water level storage test in flood season, it is proved that the reinforcement effect is better than expected. The concrete manifestation is that the water slope at the back of the original dam has a large area of leakage and humidification, and the phenomena of "cowhide swelling" and piping leakage at the ends of the two dams have disappeared, and the water level at the dam saturation line has obviously dropped by 0.5 ~ 0.9 m. According to the observation in recent four years, the Sankeng Upper Reservoir is in a stable state after reinforcement, which meets the requirements of the safe operation of the reservoir and plays a good comprehensive benefit. The practice of danger removal and reinforcement of Sankengshang Reservoir in Puning City proves that the application of automatic monitoring system for grouting construction quality in grouting engineering construction is a feasible technical measure, which can better ensure the construction quality of this concealed project.
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