基于锚杆钻机MWD的岩石强度实时估算方法及其现场注浆质量评价应用

Bailong Ma^1,2, Kai Zhang^1,2, Fangyuan Xiao^1,2, Bosong Yua³, Xinran Xue^1,2, Tao Jiang^1,2 , Houquan Zhang^1,2, Zhanrong Zhang⁴

¹China Univ Min Technol, State Key Lab Geomech Deep Underground Engn, Xuzhou 221116, Jiangsu, Peoples R China

²China Univ Min &Technol, Sch Mech Civil Engn, Xuzhou 221116, Jiangsu, Peoples R China

³Kyushu Univ, Dept Earth Resources Engn, Lab Rock Engn&Min Machinery, Fukuoka 8190395, Japan

⁴China Railway Siyuan Survey Design Grp Co Ltd, Wuhan 430063, Hubei, Peoples R China

Abstract: Grouting reinforcement is an effective method for controlling fractured rock in the deeply buried roadways of coal mines. However, quantitatively evaluating the strength of grouted rock masses remains a challenge. The design of grouting reinforcement is primarily based on empirical knowledge. Consequently, this study proposes a real-time in-situ method for evaluating grouting quality using measure while drilling (MWD) based on a roofbolter. Initially, we validated the method through a numerical study using the discrete element method. Several 3D rock samples with varying crack densities were established and drilled numerically, demonstrating that the strength of fractured rock masses can be better estimated using the rock drillability index rather than drilling specific energy. Therefore, a model, known as the P-d-R-c model, was established to estimate rock strength based on the rock drillability index. Subsequently, an in-situ validation was conducted using a self-developed MWD testing system to assess the grouting quality in fractured rock masses. The results show that the strength of the rock mass increases by 38%, 56.0%, and 49.7%, respectively, after grouting, as observed in three boreholes. This method allows for quantitative estimation of grouting quality.

Keywords: Fractured rock mass, Discrete element simulation, Drilling parameters , Rock drillability index, Drilling specific energy, Grouting quality evaluation

Fig. 2 Fissure planes

Fig. 3 Cutting bit

Fig. 4 Full-scale 3D discrete element model

Fig. 5 Fissure planes with different crack densities

Fig. 7 Drilling torque and pushing force with drilling depth in sandstone rock mass

Fig. 8 The uniaxial compression simulation test

Ma, B. et al. (2023). Real-time estimating method on rock strength via MWD of roofbolter and its application to in-situ grouting quality evaluation. Geomechanics and geophysics for geo-energy and geo-resources, 9 (1). doi:10.1007/s40948-023-00630-3