Abstract:

Aiming at the softening of some typical saturated soft rocks widely distributed in South China areas, such as silty mudstone and mud siltstone, self-organization criticality theory is adopted to analyze the critical phenomena in the softening process of soft rocks in the saturation test; and based on the test data, some conclusions are drawn as follows: the time points of three months and six months are two critical points for the interaction between water and rock; and the variation of physico-mechanical properties of soft rocks and concentration of aqueous solution both satisfy the same regularity; all the factors are changing greatly in the first three months, gently in the following three months and keeping stable after six months; while the response variation regularity of microstructures satisfies keeping original appearance during first to three months, self-adjusting to order during three to six months and entirely changing to another structure types after six months. Meanwhile, two key characteristics for self-organization criticality of soft rocks are analyzed; and from the angle of system evolvement, the developing process of a non-equilibrium self-organizing order structure in soft rock system is discussed; and the stable critical time of engineering properties variation of soft rocks is proposed.

Key words: soft rocks, saturation test, softening, critical phenomena, self-organization criticality