Rock and Soil Mechanics ›› 2020, Vol. 41 ›› Issue (6): 1887-1898.doi: 10.16285/j.rsm.2019.6448

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Experimental study on bearing characteristics of bolt-grouting in shallow fractured surrounding rock of roadway

PAN Rui1, 2, 3, CHENG Hua1, WANG Lei3, 4, WANG Feng-yun1, 2, CAI Yi1, 2, CAO Guang-yong1, ZHANG Peng3, ZHANG Hao-jie3   

  1. 1. Anhui Province Key Laboratory of Building Structure and Underground Engineering, Anhui Jianzhu University, Hefei, Anhui 230601, China 2. School of Civil Engineering, Anhui Jianzhu University, Hefei, Anhui 230601, China 3. Research Center of Geotechnical and Structural Engineering, Shandong University, Jinan, Shandong 250061, China 4. School of Civil Engineering, Ludong University, Yantai, Shandong 264025, China
  • Online:2020-06-11 Published:2020-11-11
  • About author:PAN Rui, male, born in 1987, PhD, Lecturer, research interest: underground support
  • Supported by:
    the National Natural Science Foundation of China (51904006, 51874188, 51704125, 51674154) and the Research Program of Anhui Jianzhu University (2019QDZ03)

Abstract: To clarify the bearing characteristics of bolt-grouting support in shallow fractured surrounding rock of roadway, comparative bolt-grouting bearing capacity test was carried out with different rock particle sizes, lithologies, and number of bolts. The results show that: 1) the bearing capacity of the bolt-grouting increases first and then decreases with increasing the particle size. Compared with the non-anchored specimens under the same conditions, the peak stress of the anchored specimens increases by 53.38% on average, and the peak strain decreases by 46.43% on average. 2) Under anchored condition, the free surface opposite to the supporting surface and its vicinity are the preferred area for macro-fracture development. The failure of supporting surface generally lags behind the free surface, and the specimens gradually transit from mainly tensile failure to tensile-shear mixed failure; tensile failure is the main failure mode of specimens under the condition of no anchor. 3) With the increase of bolt number, the bearing capacity of bolt-grouting increases gradually, but the growth rate slows down gradually. The peak strain slows down, which is consistent with the inflection point of peak stress growth. 4) The specimens have three characteristics of progressive destruction: firstly, the cracks generated before peak stress continue to propagate after peak stress; secondly, the surface material of support surface spalls with the crack stretching; thirdly, the cracks gradually develop from surface to inside of the specimens, the rock fragments fall off first, and then the macro-damage develops to the anchor area, resulting in the loss of overall specimen bearing capacity.

Key words: fractured surrounding rock, bolt-grouting support, rock particle size, bearing characteristics, crack propagation