A high-resolution borehole tilt-meter is introduced to measure the inclination of rock slope at an open pit limestone mine, and the movement of rock slope is analyzed based on the measured results from the tilt-meter and numerical results by a three-dimensional boundary element method (3-D BEM). Firstly, a high-resolution borehole tilt-meter is explained. Secondly, based on the measured results for nine months in the limestone mine, the mechanical behavior of rock slope is analyzed. The general mechanical behavior of rock slope due to excavation of a bench is then analyzed by 3-D BEM. Finally, using the results of measurement and numerical analysis, the mechanical behavior of rock slope is made clear. It is concluded that a high-resolution borehole tilt-meter is applicable to monitor the movement of rock slope in a short period.
Limestone deposit is only a self-sufficient resource In Japan, and being excavated at various districts to supply the material of cement and iron manufacture, gravel, and so on. The bench cut method is adopted in most open pit limestone mine in Japan. Recently, rock slopes are being excavated with increasing height and width for the improvement of mine productivity. The establishment of technique for not only the measurement and maintenance of large rock slope but also the estimation and prediction of rock slope stability becomes very important topics in rock slope engineering field.
In order to measure the movement of rock slope due to excavation, extensometer, automated polar system (APS) and global positioning system (GPS) are usually used in Japan. However, since the progress of bench becomes slow due to increasing the pit Scale of mine, a long period is necessary to obtain an effective data from the instruments installed for measurement. Furthermore, in order to predict the mechanical behavior of rock slope, mechanical properties of rock may be estimated by a back analysis based on the measured results. For this purpose, it is desired that the instrument with a high resolution is used to monitor movement of rock slope due to small volume excavation and then a valuable data is obtained in a short period.
In this paper, a high-resolution borehole tilt-meter [Castillo et al. 1997] is introduced to measure an inclination of rock slope at an open pit limestone mine, and the movement of rock slope is analyzed based on the measured results from the tilt-meter and the numerical results by a three-dimensional boundary element method (3-D BEM). Firstly, a high-resolution borehole tilt-meter is explained. Secondly, based on the measured results for nine months in the limestone mine, the mechanical behavior of rock slope is analyzed. The general mechanical behavior of rock slope due to excavation of a bench is then analyzed by 3-D BEM. Finally, using the results of measurement and numerical analysis, the mechanical behavior of rock slope in the mine is made clear. It is shown that the high-resolution borehole tilt-meter is applicable to monitor the movement of rock slope in a short period.
