Study on Dynamic Characteristics of Deep Siltstone under High Static Stress and Frequent Dynamic Disturbance

Lu-Ping Cheng,Zhu-Qiang Xiong,Li-Zhong Tang,Chun Wang,Tao Liu,Yong-Heng Wei,Cheng Wang,Shi-Ming Wei,Yuan Chen

doi:10.1155/2019/2087684

Abstract

http://mts.hindawi.com/update/) in our Manuscript Tracking System and after you have logged in click on the ORCID link at the top of the page. This link will take you to the ORCID website where you will be able to create an account for yourself. Once you have done so, your new ORCID will be saved in our Manuscript Tracking System automatically."?>The mechanical characteristics of siltstone under high static load and frequent dynamic disturbance were investigated by the improved split Hopkinson pressure bar (SHPB), which is used to simulate the failure phenomenon of the extracted ore drift owing to high stress concentration and blasting disturbance in Dongguashan copper mine at the depth of more than 900 m. The maximum dynamic strain, dynamic stress, and dynamic deformation modulus of rock of each impact were researched to provide theoretical basis for mining production. The results show that the dynamic stress-strain curves of siltstone before the peak stress present two characteristics of linear and nonlinear variation and different degrees of resilience after the peak stress under high static stress and frequent dynamic disturbance. The strain rate rises in a linear trend with the increasing times of dynamic disturbance, but the value of the strain rate is approximately constant in the process of one impact. With the increase of the strain rate, the maximum dynamic strain rises at the same static stress, while the peak dynamic stress and dynamic deformation modulus decrease linearly. Because the inner stored elastic energy of rock determines the value of resilient strain after unloading, the elastic energy may increase with the increase of static axial stress in a certain range and then the resilient strain increases. Accumulative times of dynamic disturbance and static axial stress show the relationship that the former is obviously reduced with the increase of the later.

Highlights

With the rapid development of science and technology and the increase of large deep rock engineering, the mechanical characteristics of deep rock mass under complex mechanical environment have been a frontier issue in today’s world [1, 2]
The split Hopkinson pressure bar (SHPB) test device was improved by Li et al, and they used the device to complete the test of static-dynamic coupling loading of the rock under the high strain rate [3,4,5]. is provides the experimental equipment foundation for the research of the dynamic characteristics of deep siltstone under high static stress and frequent dynamic disturbance
Yin et al [6,7,8] investigated the failure mode of the rock under static-dynamic coupling loading by the same device. e results show that the failure mode of rock samples under the combined load of static and dynamic is affected by preload axial compression and impact load, and the failure type is “V” or “X.” e study found that the failure modes of rock samples are combined shear failure or tensile failure when

Summary

Introduction

With the rapid development of science and technology and the increase of large deep rock engineering, the mechanical characteristics of deep rock mass under complex mechanical environment have been a frontier issue in today’s world [1, 2]. E above research results lay a foundation for determining the failure mode of rock samples under high static stress and frequent dynamic disturbance. Ese research works reveal that the mechanical characteristics of rocks are different with the different mechanical environments, which further indicates that it is of certain significance to study the dynamic characteristics of deep rock under high static stress and frequent dynamic disturbance. The mechanical characteristics of rock under impact load have made a certain degree of achievements, the research on dynamic characteristics of deep rock involves less in the circumstances of high static stress and frequent dynamic disturbance. Erefore, the study on the mechanical properties of rock under high static stress and frequent dynamic disturbance is of great significance to practical engineering In reality, using concentrated stress and blasting disturbance effectively to exploit the deep ore body or avoid a series of disadvantage is an urgent problem that needs to be solved in Dongguashan copper mine presently. erefore, the study on the mechanical properties of rock under high static stress and frequent dynamic disturbance is of great significance to practical engineering

Test Condition and Scheme

Experimental Results and Analysis

Conclusions