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Abstract According to construction of Longtoushan two bores and eight lanes tunnel with super-large section and span in Guangzhou，the monitoring of surrounding rock deformation was carried out. Based on the measured data，the law of the deformation varying with time and the longitudinal and radial incidences of different construction procedures were analyzed. It is shown that the surrounding rock deformation can be better controlled using the two-side pilot drifting method. During the construction of super-large section and span tunnel，the excavation of the upper bench in the right drift，the down bench in the left drift and core rock have great influence on surrounding rock deformation，which are the main stages to control the surrounding rock deformation. The longitudinal incidence of the excavation of the super-large section and span tunnel is about one time of the drift diameter，about 6 to 8 m. And the radial incidence in the vertical direction of the ceiling is about 25 m and radial incidence in the 30° direction of the ceiling in the left drift is about 15 m. The experience and conclusions presented can be used as reference in the design，construction and site monitoring of similar tunnels.
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Received: 24 January 2009
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