Abstract：The space effect of the furrow pit slope is analysed by elastic mechanics principle. The relation formula among the critical slide angle，the friction coefficient，the elastical modulus in circular direction of the circular rock，and the horizontal radius of the furrow pit is derived under the conditions，in which the rock mass is homogeneous and elastic，and loaded only by its dead weight and excavated like the reverse frustum. The relation formula shows that the deeper the furrow pit is excavated，the greater the critical slide angle is. Based on the relation formula both the theoretical basis for reducing stripping in furrow pits and the basic way to determine the figure of the stable slope are developed. The theory not only includes the conventionl principles for analysing the stability of slopes but also is available for analysing the stability of furrow pits. The great economic efficiency may be obtained by using the camber curve as the figure of furrow pits.
