科研之友
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摘要
Karst problems often result in unexpected additional building costs and the proper understanding of karst terrains is therefore important for geotechnical engineer. The karst terrain is developed from the dissolution of carbonate rock. Groundwater flow through carbonate rock enhances the dissolution of carbonate minerals which can cause the development of subsurface cavities or voids. The subsurface cavities and uneven depth of bedrock make foundation design very difficult in karst terrain. A subsurface characterization and grouting case study are presented for the Yongweol-ri site, South Korea. In the project area, mortar was injected into subsurface cavities for consolidation and/or grouting purposes. The subsurface cavities were imaged using electrical resistivity and borehole camera (BHTV) before and after mortar injection. In addition, the resistivity changes of mortar specimens were studied in the laboratory simulating various field conditions. The injected mortar was imaged as anomalies exhibiting lower resistivity than the surrounding rocks. A comparison of the pre- and post-grouting resistivity provided detailed information of the subsurface cavities plus the areas which have been occupied by the mortar after consolidation. Also, BHTV field test confirmed the presence of the mortar in the subsurface cavities. The results obtained from this study showed that electrical resistivity imaging can be a useful tool for detecting and evaluating changes in subsurface resistivity due to the injection of the mortar. From the laboratory analysis, it is confirmed that mortar is a good material for grouting and ground stability hazard management.
- 出版日期2013-1
