Study on the Allowable Exposure Time of Temporary Goaf in the Open Stope and Backfill Mining Method with Large Structure Parameters

Xiaosheng Liu,Yizhong Luo,Jin Zhan,Weijun Wang

doi:10.1155/2020/8853410

Abstract

Based on the uniaxial rheological experiment data of iron ore rock mass and filling body in large-scale stope obtained by using the rock servo controlling creep equipment, the characteristics of the creep curve were analyzed. The creep models of iron ore and filling body which can show the attenuation creep of rock were constructed. And a nonlinear creep model was obtained. According to the rheological data of the iron ore and the filling body, the parameters of the new nonlinear creep model were identified to obtain the material parameters of the creep model. Then, the creep model parameters were fitted and reduced to calculate the reasonable exposure time of temporary goaf in the large-scale stope. The results show that the reasonable exposure time of stope is 520 ～ 650 days, and the reasonable exposure time of filling body is 410 ～ 520 days. The model can well describe the initial attenuation creep stage and steady creep stage in the creep curve, which proves the correctness and rationality of the model. The study provides a reference for mining design and safety production of similar mines with large-scale stope structure.

Highlights

A large number of instability phenomena are related to the creep characteristics of rock
Rock creep is one of the important reasons for the deformation and instability of surrounding rock in rock engineering [1–3]. e rheological property of rock means that the rock presents deformation, fluidity, failure, and other properties with time under the conditions of external load and temperature, mainly presenting the properties of creep, stress relaxation, elastic aftereffect, strain rate effect, aging strength, rheological damage, and fracture [4–6]
In the past few decades, many scholars have carried out experiments on rock creep characteristics and obtained the conclusion that the rock creep continuously adjusts and recombines with time, resulting in rock stress and strain which continuously increase and change with time [7–11]

Summary

Introduction

A large number of instability phenomena are related to the creep characteristics of rock. There are few papers on the creep research for the cemented filling body in large-scale stope mined by the backfill mining method. E uniaxial creep tests are carried out on the iron ore rock and filling body under the loading conditions to study the deformation characteristics of rock and filling body under different stress states. In order to determine the creep parameters of iron ore and filling body in the underground stope of an iron mine in a short period of time through the test, so as to study the time effect of rock stability, uniaxial compression creep experiment is chosen for the study. Due to the long time of creep experiment, this study chooses the quartz specularite and the filling body with cement-sand ratio of 1 : 6 as the experiment objects.

Iron ore Filling body

EKEB ηKηB σ

Findings

Conclusion