Hue which is a kind of subtle visual effect, is generally born of the factors, such as the relationship between cold and warm colors, the contrast between light and shade as well as the impression of space.

Five corresponding points of teaching of charcoal drawing were found through analysis of the uniqueness,which were the training of details,the training of abstract composition,the training of light and shade,the training of materials,and the training of view point and view angle.

Because of complex geologic situation and serious bias of Dianhuiping tunnel exit ,it appears dangerous situation such as hillside landslide, hillbody continual displacement in the course of construction of half bright and half dark, half tunnel and half road construction.

Concrete applying example of open tunnel subsurface excavation in tunnel construction;

This paper introduces the general situation of a certain engineering, expounds the construction plan and working procedure of the dark operation in open tunnel, and discusses on the key construction techniques and the monitoring and measurement.