关键词: 钻孔摄像技术, 珊瑚礁, 尺寸效应, 岩体完整性, 密度函数, 完整性指数

Abstract: At present, relatively few drilling surveys have been conducted on coral reefs, and comprehensive geological info on coral reefs is difficult to obtain. However, research on coral reef is of great importance to our development and exploitation of maritime resources. The survey of Chenhang Island in Paracel (Xisha) Islands saw China’s first usage of digital borehole camera technology, which resulted in a large amount of first-hand geological data, but the traditional rock mass integrity index (RMDI) method is not suitable for coral reef rock mass. To evaluate the size effect of cavities on coral reef rock mass, we proposed the concept of coral reef cavity density, and established the coral reef cavity density and block functions. Afterwards, the value of coefficient ? in the RMDI can be determined; the integrity index density function (DIDF) can be reconstructed; and then ultimately the coral reef RMDI can be determined and used to evaluate the coral reef rock mass integrity. The evaluation method is applied to the borehole CK1 of Chenhang Island in Paracel Islands. The evaluation results are generally consistent with other evaluation methods. Some conclusions are drawn as follows. High-resolution borehole images can provide reliable results for evaluation of coral reef rock mass integrity. The cavity density function can reflect the distribution of cavity effects on coral reef rock mass along the axial direction; DIDF is a good representation of coral reef rock mass integrity along the axial direction; The RMDI method is a feasible approach for the evaluation of coral reef rock mass integrity along the full or partial depth of a borehole.

Key words: borehole camera technology, coral reef, size effect, rock mass integrity, density function, integrity index