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Abstract The deformation-controlling theory of rock mass structure，a basic theory in engineering geology，is critically important for understanding the deformation and failure patterns of rocks. It is also essential for calibration of mechanical parameters and stability evaluation of rock masses. At present，artificial construction- induced disturbance is intense；and the dynamic variations of rock mass discontinuities and the rapidly intensive excavation disturbance associated with engineering performances become extremely complicated. The strength criteria of rock mass need to be considered in combination of rock deformation monitoring. Therefore，the dynamic control and adjustment of the rock mass structure are one of great challenging issues for engineering geologists. Although it is not easy to predict geological defects，we need to know the dynamic variations of geological structures in terms of construction-induced geohazards. Consequently，the controlling effects should be updated with elapsed time. Based on this，the discontinuity dynamic adjusting and controlling opinion(DDC) is put forward，which may be as attributed to the development of rock mass structure controlling theory. For comparison，a case of the Shanggongshan tunnel was employed where dynamic control and adjustment of rock mass during construction were not considered. Various geological defects such as caves and faults along the anticline axis were unexpectedly encountered in construction of this project. Thus，back analysis of the TBM accidents which were time-consuming and caused frequent variations in designs was performed to better understand this issue. This case shows that the dynamic changes in rock mass structure are the results of excavation-induced disturbances. Consequently，counter-measures are to be considered in the framework of the proposed DDC to avoid those unexpected results.
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Received: 05 November 2012
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2013, Vol. 32 
