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Show I t is then possible to replace f by \ I - 2 M ) ( 20) With reference to the f, of Equation ( 11), it is possible to define the limiting angle of incline, ty , for the " secondary absolute stability" of a slope as / ' . '- ZM W r » i - M '• ( 21) If the slope angle, tr is less than Tj , then the slope remains stable in spite of an arbitrarily large radius of fracture in the critical layer. The X dependence given by Equation ( 14) suggests that the increase in stress is finite even if the radius of the fracture line becomes infinite. However, if stress is propagated according to an exponential law, then the stress may diverge. This problem has not been solved for snow, although Bossinesq ( see Kollbrunner) has worked on a similar theory for soils. When the radius of the fracture line is small, the increase in stress is lower than the value given by Equation ( 16). It varies at first as f0 and then approaches assymptotically a radius of the same order of magnitude as depth The second extreme case, an extended horizontal fracture line, can be represented by a band of width Z% 0'\ r\ the x- direction and infinitely long in the z- direction ( see Fig. 2). For this case the increase in stress is AT = X - o ( 22) |