XIN Y J, DONG S, JI H Y,et al.Mechanical properties and instability mode of multi-hole cement specimens strengthened by filling[J].Journal of Henan Polytechnic University(Natural Science) ,2023,42(2):144-152.

doi:10.16186/j.cnki.1673-9787.2021010090

Received:2021/01/19

Revised:2021/06/08

Published:2023/03/25

Mechanical properties and instability mode of multi-hole cement specimens strengthened by filling

XIN Yajun1,2, DONG Shuai1, JI Hongying3, WANG Yu1, YANG Junpeng1

1.School of Energy Science and Engineering，Henan Polytechnic University，Jiaozuo  454000，Henan，China；2.Collaborative Innovation Center of Coal Work Safety，Henan Polytechnic University，Jiaozuo  454000，Henan，China；3.Institute of Resources and Environment，Henan Polytechnic University，Jiaozuo  454000，Henan，China

Abstract:For discovering bearing characteristics on filling reinforced surrounding rock in mining gateway after borehole pressure relief，uniaxial compression mechanical tests were operated on two groups of eight multi-hole specimens by rigid testing machine on the basis of analysis on stress distribution and crack development of multi-hole specimen.Instability modes and failure forms of multi-hole specimens before and after being filled were determined.The results showed that，free surface increased in multi-hole specimens，stress concentrated and overlapped obviously，and cracking around hole was obvious.The more the hole number was，the smaller the strength of multi-hole specimen was，while the strength of filled specimen was higher than the no-filled one，the strengthen ranges were 3.37%~16.78%.When filling material strength was less than multi-hole specimen，axial deformation of filled multi-hole specimen decreased with hole number increasing.Compared with the no-filled specimen，the less hole number was，the smaller the deformation of filled specimen was.Failure ways of filled specimen was divided into two types：the failures along weak bonding surface and along filled mass，and the filled and no-filled specimens showed respectively curve free instability and block directional one.The research results could provide reference for the filling parameter selection of relief-pressure hole in deep gateway surrounding rock.

Key words:multi-hole specimen;filling strengthening;porous line;instability mode

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