Jinjiguan tunnel on Chuan-Zang highway at Ya-an was entirely open to traffic on January of 1995

however

about in 2001 the two tunnels of it appeared water penetration and deformation to a different degree with crevices and upheaval. Based on the author′s investigation and analysis at field and antecedent studies

it was three factors which resulted in the Jinjiguan tunnel′s all kinds of defects: the first factor was geological factor that was expansive soils in Guan-kou （lithostratigraphical unit） expanded to cause arch and road surface upheaval on encountering water; the second was that the groundwater dissolving the gypsum in Guan-kou seeped and recrystallized along toroidal crevices caused by the third factor construction reason. All the defects are mainly caused by the inducing factor groundwater

and on the base of these studies

the author offered some measures to control the defects

of which main measures are to cure surface water and groundwater surrounding the tunnel.