ABSTRACT:

Based on the problem of underground continuous diaphragm wall in the east of Yanshan open-pit slope of iron mine, Si Jiaying, three typical sections of the slope are selected and calculated with numerical simulation method, slope stresses under water inflow condition and apply underground continuous diaphragm wall method are analyzed. Results showed that the slope stability is not up to standard under water inflow condition and there exists local instability phenomenon. After applying underground continuous diaphragm wall to control water, slope stability is improved significantly and up to the requirements.

1 INTRODUCTION

Yanshan Iron Mine is an important iron ore production base of Hebei Iron and Steel Group Mining Co, Ltd, which is an open-pit mine, with an annual output of 7 million tons. Luan River lies there and flows southward into the Gulf of Bohai. There contains strong permeability sand and gravel layers with large amount of water. Majority ores are buried beneath local erosion base level and covered by Quaternary topsoil. The layer thickness is 10m-30m, the thickest is about 65 m, eastern quaternary is alluvial sand as well an sand and gravel layer, pore phreatic aquifer is strong water permeable and rich aqueous. The new path of Luanhe, which is about 60 m away from the stope, will serve as the constant head water supply. Large amount of water gushes to the stope from the new river through its east side as water channel and the stability of the east slope is severely affected.

In order to guarantee the east slope stability, the water control project is implemented. There are curtain grouting and underground continuous wall among existing projects. Gushan Iron Mine implements the curtain grouting water project in the east-slope and has achieved good control effect (Wang et al. 2005, Deng et al. 2002, Li et al. 2007), Dragon gorge iron ore takes underground continuous wall project and the effect is good (Wang et al. 2008), Deep foundation pit slope adopts curtain grouting water control technology and effectively improves the stability (Jiang & Zhang 1997, Zheng et al. 2012, Guo 2012).

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