• Geomechanics and Engineering
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• v.39 no.3
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• pp.283-303
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• 2024

In large-scale engineering construction, there are many cases of highly concealed adverse geological phenomena (HCAGP) at certain scale that are not revealed until excavation. It is crucial to ascertain their geological characteristics and rapidly formulate treatment since they often have enormous negative impacts on the project. However, conventional exploration and evaluation methods are not suitable for HCAGP due to the long acquisition time and strict requirements. Therefore, this paper proposes a dynamic-tracking investigation and evaluation method (DTIEM), which carries out a series of fast and effective techniques, including down-the-hole (DTH) drilling, cross-inclined holes, seismic tomography and P-wave velocity (V_P) tests, for preliminary data of HCAGP. Then, an initial treatment plan is proposed to guide the construction. Subsequently, the initial data of the HCAGP are tracked and revised until the end of construction. This method was applied to a deep groove at a hydropower station, which was exposed when the excavation of dam section 11. The results show that by using the DTIEM, the preliminary engineering characteristics of the deep groove were obtained quickly. The rock mass quality of the top deep groove was grade III₂ with 9.82 GPa, the middle part was grade III₁ with 15.07 GPa, and the bottom part was grade II with 19.68 GPa. The quality of rock mass gradually increases with the increase of depth. From the numerical simulation, the maximum additional displacement is about 20 mm at the dam crest, 4 ~ 7 mm at the dam heel, and 2 ~ 5 mm at the dam toe. The numerical simulation and monitoring results show that the stress and strain of the dam and foundation are within a safe range in each stage. Thus, the proposed method is feasible.