Abstract:

Owing to abundant argillaceous minerals, argillaceous rocks often take on notable dilatability, in particular the lower diagenesis argillaceous rocks formed during Mesozoic and Cenozoic, which is the main type. After general analysis of existing discrimination factors, it is presented that the montmorillonite content, cementation coefficient and surface area are as three main indices for dilatability identification and grading of argillaceous rock. According to projection pursuit cluster statistical method, some analyses of twenty samples coming from Daban tunnel in China’s Xinjiang Autonomous Region are done. Based on moving average trend line of the sample's projection value, these argillaceous rocks can be divided into four grades, just as no-swell, micro-swell, weak-swell and strong-swell, which is approximately in accord with the result by dry block saturation water absorption index, so, here the factor and distinction way are reliable.

Key words: swell rock, distinction index, projection pursuit