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Abstract Due to excavation blasting，the surrounding rock of underground caverns is loosened and its strength lowers. A continuous three-dimensional data field of surrounding rock parameters is employed to describe the different damage degrees of surrounding rock. According to the formation mechanism of excavation damaged zone(EDZ) of surrounding rock，the method to calculate the EDZ induced by excavation blasting in underground caverns is analyzed. By taking the range of EDZ into consideration，a back analysis method based on incremental displacements is put forward. By employing this method，the fields of surrounding rock parameters can be back analyzed. As back analysis of geotechnical engineering involves enormous amounts of computation，the back analysis process is improved by introducing message passing interface(MPI)-based master-slave parallel framework. The parallel computation can be conducted using computer cluster networks，thus considerably reduce the cost and enhance the efficiency of computation. The proposed method is further illustrated with its application to the large-scale underground caverns of Xiluodu hydropower station. The back analysis results are favorable and the reliability and rationality of the proposed method are proven. Based on the surrounding rock parameters field obtained by back analysis，the current anchor support scheme and the stability of the underground cavern are assessed. Also，the stability condition in subsequent excavation is predicted；and the rational recommendations are made for the engineering design and construction，providing the parameters back analysis of underground engineering with a new method.
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Received: 28 November 2008
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