Field-based calibrated numerical modeling of longwall tailgates/headgates: anisotropic brittle failure characteristics in shale roofs
WU Fan1, ZHAO Gaobo2, 3*, GUO Wenbing1, 4, LI Longxiang5
(1. School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000, China; 2. Department of Mining Engineering, West Virginia University, Morgantown 26505, USA; 3. Hard Rock Mechanics Department,
RESPEC (USA) LLC, Rapid City, 57703, USA; 4. Key Laboratory of Xinjiang Coal Resources Green Mining,
Ministry of Education, Xinjiang Institute of Engineering, Urumqi, Xinjiang 830023, China; 5. School of Energy
and Mining Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China)
Abstract：Laminated shale is a common roof type in coal mine roadways, where its significant anisotropic brittle characteristics often induce asymmetric large deformation and roof fall accidents. However, existing numerical simulation studies frequently overlook the influence of bedding plane orientation and lack calibration against in-situ measurements, making it difficult to accurately reveal the mechanical properties and deformation patterns of shale roofs. Based on in-situ measurements from five typical U.S. coal seams (e.g., Lower Kittanning and Pittsburgh), this paper proposes a systematic model calibration workflow combining theoretical analysis and numerical simulation. The procedure includes: calibration of vertical and horizontal stresses, calibration of roof sag and cable bolt loads, and verification of anisotropic brittle failure characteristics. Subsequently, a FLAC3D roadway numerical model incorporating an anisotropic brittle failure criterion was established, realizing the coupled characterization of anisotropy in shale strength and elastic modulus, cohesion-weakening friction-strengthening behavior, and dilatancy features. Furthermore, roadway models covering four typical mining geological conditions were constructed: highly laminated shale roofs, high horizontal stress, deep three-pillar systems, and single-pillar systems. The simulated ranges of vertical stress (5–48 MPa) and horizontal stress (6–42 MPa) effectively cover the geo-stress conditions of most U.S. coal seams. Compared with traditional methods, the calibrated model more accurately characterizes strata behaviors, such as stress distribution, roof sag, cable loads, and failure patterns. It reveals the asymmetric failure mechanism of laminated roofs and clarifies the risk of roof cutting and large deformation in single-pillar systems. This study deepens the understanding of the anisotropic brittle failure mechanism of laminated shale at the entry scale and provides a reliable numerical analysis framework for the stability analysis of longwall tailgates/headgates under complex geological conditions.
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2026, Vol. 45 
