For small clear space tunnel,because the width of middle-rock wall is as small as 5 to 7 m,the loosening zone of two tunnels could be overlaid during the process of construction which results a large vertical displacement of middle-rock wall and leads to the augment of span of slumping arch and stress raising of th.

Sandwiched rock between twin closely spaced tunnels is in complicated and three-dimensional stress state.

Ba sed on Changsha Chaoyang Second Rebuild Project, introduced performance, conformation, technical requirement and construction skills of steel net supporting perlitic wallboard; elaborated on the construction outline, matters need attention and quality requirement.

Petrochemical research on intermediate-basic dykerocks in Xiaoqinling,Xiong ershan goldfield,Henan province,Central China;