LU W B,ZHANG D,HE Y X,et al．Experimental study on strength failure characteristics of columnar jointed rock mass under triaxial stress[J].Journal of Henan Polytechnic University( Natural Science)，doi:10.16186/j.cnki.1673-9787. 2024100032.

doi:10.16186/j.cnki.1673-9787. 2024100032.

Received: 2024-10-23

Revised: 2024-11-14

Online:2024-11-19

Experimental study on strength failure characteristics of columnar jointed rock mass under triaxial stress (Online)

LU Wenbin,Zhang Dong,HE Yanxin,Tuo Zhiwei

1.School of Computer Science and Technology, Henan Polytechnic University, Jiaozuo 454000, Henan, China；2. Henan International Joint Laboratory of Coalmine Ground Control, Jiaozuo 454000, Henan, China；3.School of Water Conservancy and Civil Engineering, Shandong Agricultural University, Tai’an 271018, Shandong , China

Abstract: Objectives The columnar jointed rock mass(CJRM) in the dam site area of Baihetan Hydropower Station of Jinshajiang River has the characteristics of abnormal development of structural surface, significant anisotropic characteristics, and easy to relax and rupture after excavation, etc. In order to ensure the safety of the construction, it is necessary to carry out an in-depth study on its mechanical properties. Methods According to the similarity theory, the complete specimen without joints and the hexagonal prismatic model specimen with different joint inclinations were prepared by using similar materials such as gypsum, river sand and water, and uniaxial compression tests and triaxial compression tests were carried out by using true triaxial testing machine. Based on the experimental results, the strength and deformation curves were plotted, and the strength characteristics, stress-strain relationship and damage modes of CJRM under different stress conditions were investigated. Results The test results showed that, unlike the intact specimens, the strength and deformation of the columnar joint model specimens showed significant anisotropic mechanical characteristics under different stress environments, and the presence of joint surfaces had a significant effect on the weakening of the strength of the model; the peak strength of the two types of specimens increased with the increase of the peripheral pressure, and the strength and elastic modulus of the joint specimens under uniaxial compression with the change of the nclination angle β showed a ‘U’ line, and the peak strength of the specimens in triaxial compression with the increase of β was divided into two types, i.e., it decreased firstly and then increased (σ₃=1MPa) and there was no obvious rule of change (σ₃=1.5MPa,2MPa); With the increase of the peripheral pressure, the damage modes of the joint specimens changed from brittle to plastic, and the anisotropy ratio R decreased; Based on the results of the test of the model specimen damage mode; the damage modes of the model specimens were classified according to the test results, and four typical damage types of the specimens under three-dimensional stress conditions were summarised. Conclusions The results of the study could not only provide an in-depth understanding of the engineering mechanical properties of columnar jointed basalt, but also provided a reference for the theoretical study and engineering analysis of the problems related to complex jointed rock mass.

Key words: columnar jointed rock mass; triaxial compression; Baihetan Hydropower Station; peak intensity; destruction mode