THE EFFECT OF CONFINING PRESSURE AND THE POSSIBILITY OF ARGILLIZATION OF WEAK INTERCALATIONS
Zhang Xiangong, (China University of Geosciences, Beijing)Nie Dexing(Chengdu College of Geology, Chengdu)Han Wenfeng(Lanzhou University, Lanzhou)
The formation of weak intercalations and their, stance features are strictly controlled by the surrounding geological environment, especially by the crustal stross. Release of the crustal stress causes the physical properties of the weak intercalations in the strongly weathered zone and moderately weathered zone to become poorer; thus argillization happens when they are saturated; and physical indices and mechanic strength indices drop down. On the contrary, the weak intercalations in the slingtly weathered or unweathered zone possess better physical properties and higher strength indices under confining pressure caused by the crustal stress. Even when the weak intercalations are saturated, argillization is impossible because the confining pressure is in excess of their expansive force. The indices obtained through the weak intercalation strength test carried out at present are much lower than their natural indices, for the release of confining pressure causes the weak intercalations to soak water and thus be argillized. So, these indices cannot represent their natural strength properties. The authors consider that the confining pressure caused by the crustal stress is the main cause for weak intercalation argillization.