Abstract: The continual uplift of the Qinghai-Tibet Plateau results in the strong uplift of the fault block of Lonshou Mountain between a pair of regional conjugated faults.In the fault block, there are two fault systems in longitudinal and horizontal distribution, under the effect of which, two groups of superior joint planes are developed in the rockmass.For a zone with strong fault activity, its faults and the joint planes of the rockmass, to the ground stress field, should approach the critical sliding state.The calculation of the friction force between the joint planes, which is made according to the practically measured stress data and the friction coefficient between the joint planes of the rockmass, does equal the maximum static friction force.Thus the mechanical calculation result conforms to the geoscienctific viewpoint and it can be seen that the weak intercalations in Jinchuan Mine have decisive effect on the accumulation degree and distribution state of the ground stress.

Key words: Ground stress field, Joint plane, Fault, Weak intercalation