Dynamic Characteristics of Deep Dolomite Under One-Dimensional Static and Dynamic Loads

Jianguo Wang,Kegang Li,Yang Liu

doi:10.1007/s40030-019-00424-5

Abstract

The failure characteristics of rock subjected to impact disturbance under one-dimensional static axial compression are helpful for studying the problems of pillar instability and rock burst in deep, high geostress surrounding rock under blasting disturbances. Improved split Hopkinson pressure bar equipment was used for one-dimensional dynamic–static combined impact tests of deep-seated dolomite specimens under axial compression levels of 0, 12, 24, and 36 MPa. The experimental results demonstrate that the dolomite specimens exhibit strong brittleness. The dynamic strength always maintains a strong positive correlation with the strain rate when the axial compression is fixed; when the strain rate is close, the dynamic elasticity modulus and peak strength of the specimens first increase and then decrease with the increase in axial compression, and the peak value appears at 24 MPa. The impact resistance of specimens can be enhanced when the axial compression is 12 or 24 MPa, but when it increases to 36 MPa, the damage inside the specimen begins to cause damage to the dynamic rock strength. Prior to the rock macroscopic failure, the axial static load changes the rock structure state, and it can store strain energy or cause irreversible damage.

Highlights

Hard rock mining cannot be separated from blasting
The failure characteristics of rock subjected to impact disturbance under one-dimensional static axial compression are helpful for studying the problems of pillar instability and rock burst in deep, high geostress surrounding rock under blasting disturbances
The dynamic strength always maintains a strong positive correlation with the strain rate when the axial compression is fixed; when the strain rate is close, the dynamic elasticity modulus and peak strength of the specimens first increase and decrease with the increase in axial compression, and the peak value appears at 24 MPa

Summary

Introduction

Hard rock mining cannot be separated from blasting. While ensuring effective crushing of the exploded rock mass, it will inevitably cause disturbances to the structures of deep pillars and floors, among others. Using SHPB testing equipment, combined with the deep copper mine ground pressure of lion rock, we selected 12, 24, and 36 MPa as three horizontal axial static pressures on dolomite samples to conduct one-dimensional dynamic–static combined impact tests and a conventional uniaxial impact test, and explored the effects of axial compression on the rock dynamic mechanical properties in terms of the stress–strain curve, strength of character, strain rate effect, and destruction form. The maximum horizontal principal stress in the middle section No 15 of stoped ore is 37.7 MPa, the minimum horizontal principal stress is 14.48 MPa, and the vertical principal stress is higher than 10 MPa. The dynamic mechanical properties of dolomite under the combined action of axial static and impact loads in one dimension were studied to describe the mechanical properties of rock subjected to disturbances under the complex stress environment of the deep mine accurately. Lithology Loading rate (MPa/ Density (kg/ Wave velocity (m/ Compressive strength s) m3)

Analysis and Discussion of Experimental Results

Findings

Conclusion and Discussion