In-situ stress measurements and regional stress field assessment of the Beishan area, China

Geomechanical Studies on Granite Intrusions in Alxa Area for High-Level Radioactive Waste Disposal

“…It is obvious to see that the boreholes NRG01 and NRG02 show quite better rock mass quality than the boreholes TMS01 and TMS02, while the borehole NRG01 shows better quality than the average condition of the nine boreholes from the Beishan area. According to Figure 8, RQD measured for borehole NRG01 shows the best quality, and most of the RQD values are higher than 90%, although some poor cases are observed at the depths around 300 m and 540 m. For the boreholes TMS01 and TMS02, the rock quality is very poor in the shallower depth, and it becomes better with the increase of depth; however, it is still not good enough at the depth of 400~600 m. For borehole NRG02, rock mass quality in the shallower depth is better than the cases in TMS01 and TMS02, but it becomes very poor at the depth of 400~600 m. Figure 9 shows the RQD measurements in the boreholes drilled in Beishan (BS) area [4], and it can be found that the boreholes BS05 and BS06 show the best rock mass qualities. In the Alxa area, only borehole NRG01 shows comparable RQD values with these two boreholes in the Beishan area.…”

“…A detailed comparison on the proportion of different rock mass qualities based on the boreholes of TMS01, TMS02, NRG01, NRG02, as well as the nine boreholes from Beishan area [4] is presented in Table 1 and Figure 10. It is obvious to see that the boreholes NRG01 and NRG02 show quite better rock mass quality than the boreholes TMS01 and TMS02, while the borehole NRG01 shows better quality than the average condition of the nine boreholes from the Beishan area.…”

“…It is defined as the intact core pieces longer than 100 mm in the total length of a core run. RQD closer to 100% means better quality of the rock mass, and an RQD-based classification is always adopted as follows: 0%~25% (very poor rock quality), 25%~50% (poor rock quality), 50%~75% (fair rock quality) and 90%~100% (very good rock quality) [4,18].…”

“…In the past few years, site characterization and selection focused on Beishan area, Gansu Province in northwestern China, and a series of studies has been conducted involving geological mapping, surface and borehole geophysical survey, hydraulic conductivity testing, in situ stress measurement, rock mechanical testing, and so on [4,11,12]. For a comparative study during the site selection period, Alxa area in Inner Mongolia Autonomous Region is chosen to be Various investigations and research have been carried out in Alxa area.…”

“…It is required to carry out extensive research, including tectonic movement, hydraulic conductivity, climate change, engineering stability, human activities, etc., to ensure that the biosphere can be protected from the pollution of radionuclides for a long period. The geomechanical study is of great importance to evaluate the structural characteristics, short-term and long-term deformation and damage behavior of host rock mass, and it has played significant roles in site selection and field experiments in the underground research laboratories (URLs) in many countries [1][2][3][4][5][6][7][8][9].…”