Abstract: Grouting is the most commonly used method in the foundation treatment of hydraulic structures. It can block cracks or fractures of the dam foundation rock mass to meet the design requirements, such as seepage resistance, structural strength, etc. The fracture is the most basic structural surface of the water permeability and the filling degree of grout is the most direct manifestation of grouting effect. However, due to the hidden feature of the grouting project, it is difficult to obtain the filling characteristics of the cracks directly. At present, the indirect water pressure test is the most method in grouting evaluation. The 360°borehole wall image obtained by borehole camera technology is used to identify the characteristics of fracture filling. Then an evaluation index based on the characteristics of fracture filling is put forward, which is called borehole fracture filling integrity(BFFI). The relationship between BFFI and permeability is discussed and the function relation of two evaluation indexes is established using the cubic polynomial. Based on the conventional evaluation method of water pressure test, the BFFI standard for grouting effect evaluation is established. The method is applied to the Yalong River Tongzilin hydropower station test grouting workshop, verifying the reliability of the proposed evaluation method. The results show that: (1) The results of water pressure test method and the BFFI method grouting effect evaluation are consistent, so as to further illustrate the feasibility of BFFI method to evaluate grouting effect. (2) The evaluation of grouting effect can be carried out based on the technology of borehole camera, which can not only show the filling situation of the grout in the fractures, but also reflect the grouting effect. The method based on fracture filling characteristics provides a new idea for grouting effect evaluation.

Key words: grouting effect evaluation, borehole camera, fracture filling characteristics, packer permeability test, borehole fracture filling integrity(BFFI)