Abstract
The dam of Guanyinyan hydropower station is composed of a concrete gravity dam in the left bank and a rockfill dam in the right bank. During the operation of the hydropower station, several surface cracks occurred in the concrete gravity dam, which threatened the stability of the dam. To evaluate the evolution trend of the cracks and forecast the potential risk of the dam, the microseismic (MS) monitoring technique and finite-element method were used. First, the concrete three-point bending field test was performed to prove the reliability of the MS technique in monitoring the concrete cracks. The MS monitoring results were consistent with the simulation results. Then, the MS monitoring system was installed in the dam body. By analysing the MS activities before and after the impoundment, the evolution trend of the cracks and potential risk of the dam were evaluated and forecasted. The simulation results were also consistent with the monitoring results. These results can provide significant references for the operation safety of the dam and also present a new thought for the risk evaluation of similar dam engineering.
Highlights
Concrete dams are commonly large with complex structure design and construction process
From the X-Y plane view, we find that the MS events mainly concentrated in two areas before the impoundment (Figure 11(a) within the red dashed boxes): on the left side of the upstream end and around and on the right side of the cracks
The main conclusions are as follows: (1) According to the comparative analysis between the field three-point bending test and the numerical simulation, the fracture mode of the concrete in the numerical simulation is consistent with the result of the field test, which proves the feasibility of the MS monitoring system in monitoring massive concrete microfractures
Summary
Concrete dams are commonly large with complex structure design and construction process. Using the microseismic (MS) monitoring technique, the microfracture signals can be received By analysing these signals, the properties of the microfractures (i.e., time, location, energy, and magnitude) in the concrete dam can be deduced using data inversion. The dam operated at a low water level for a long time, and large horizontal cracks significantly expanded. Cracks occurred in a wide area on the upstream and downstream faces of the dam and continuously developed afterwards. Cracks occurred in a large area on the downstream face close to the skewback and continuously developed in the subsequent eight years. Is evaluated and forecasted based on the monitoring and simulation results, which provides a significant technological method to forecast massive volume concrete engineering in hydropower construction
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