Engineering geological investigation of tectonic fractures in the region of Changjiang Gorges Water Conservancy Project

Abstract

The Changjiang Gorges Water Conservancy Project is proposed to be built in a crystalline rock region. The rock has been subject to repeated tectonic movement, resulting in well-developed fractures which give rise to engineering geological problems in constructions. The geological investigation in the region shows that there exist strong regularities in the developing direction and mechanic properties of tectonic fractures which constitute three distinct tectonic systems. The tectonic fractures with different mechanical properties have different engineering geological characteristics. This is represented by the different lithologic characters and permeabilities of the tectonite. The development of tectonic fractures exerts a marked influence on further development of a weathering crust and formation of a deep trough in the river bed. The structural features of the rock masses composed by various associated fractures affect the stability conditions of the dam foundation, underground chamber and deep excavated slope to different degrees. The engineering geological problems arising from the tectonic fractures can be solved by treatment of packing, grouting and anchoring.