ORIGINAL STATE OF STRAIN ENERGY IN A ROCK MASS AND ITS EFFECT ON EXCAVATION-INDUCED DISPLACEMENT FIELDS

Because of the suspects on the theory of unloading rebound,three experiments are performed;and it is noticed that some interesting phenomena that are not understood previously are discovered.Based on the observed phenomena,a hypothesis on the original state of strain energy in a geological body after diagenesis,which is different from present theories,is advanced.On the hypothesis,there is no strain energy in a geological body after diagenesis unless other external forces act on it.This new hypothesis gives a possible reason for the surface subsidence around an open pit.The constitutive equation by which the behavior of the cast material body is characterized in one of the three experiments is established.A new computer program is developed;and it is employed in trial examples of simulation of displacement fields from excavation;and satisfactory results are obtained.The achieved results agree well with in-situ measurements in direction of displacement vectors as well as in relative magnitude.The question when a geological body after tectonic movement(s)is excavated,is discussed,whether or not its original state of strain energy will cause up-rebound strain.