Investigation of Deep Shaft-Surrounding Rock Support Technology Based on a Post-Peak Strain-Softening Model of Rock Mass

Jianjun Zhang,Baicong Yao,Chuang Sun,Yang Wang,Dongxu Chen,Baoxin Jia

doi:10.3390/app12010253

Abstract

To control the large deformation that occurs in deep shaft-surrounding rock, the post-peak strain-softening characteristics of deep jointed rock mass are discussed in detail. An equivalent post-peak strain-softening model of jointed rock mass is established based on continuum theory and the geological strength index surrounding rock grading system, and numerical simulations are performed using FLAC3D software. The convergence-constraint method is used to analyze the rock support structure interaction mechanism. A composiste support technique is proposed in combination with actual field breakage conditions. During the initial support stage, high-strength anchors are used to release the rock stress, and high-stiffness secondary support is provided by well rings and poured concrete. This support technology is applied in the accessory well of a coal mine in Niaoshan, Heilongjiang, China. The stability of the surrounding rock support structure is calculated and analyzed by comparing the ideal elastic-plastic model and equivalent jointed rock mass strain-softening model. The results show that a support structure designed based on the ideal elastic-plastic model cannot meet the stability requirements of the surrounding rock and that radial deformation of the surrounding rock reaches 300 mm. The support structure designed based on the equivalent joint strain-softening model has a convergence rate of surrounding rock deformation of less than 1 mm/d after 35 days of application. The surrounding rock deformation is finally controlled at 140 mm, indicating successful application of the support technology.

Highlights

The scale of modern industrial production is rapidly expanding and the demand for mineral resources continues to increase
On-site monitoring showed that the supporting structure of the actual original supporting plan 2 produced three different degrees of damage, and the surrounding rock had no obvious convergence trend
The convergence–constraint method was adopted to calculate the stability of the surrounding rock support structure of a vertical shaft in a large deep fault crushing area using two mechanical models

Summary

Introduction

The scale of modern industrial production is rapidly expanding and the demand for mineral resources continues to increase. The contradiction between the development demand and shallow resource shortage has gradually driven mining engineering to exploit increasingly deep and ultra-deep mining environments, which has led to new challenges because deep rock mass has considerably more complex mechanical properties than shallow rock mass. The so-called problem of “three highs and one disturbance” (i.e., high ground stress, high temperature, high karst hydraulic pressure, and intense mining disturbance) is prominent in such rock mass. These complex environmental conditions lead to a series of large nonlinear deformation phenomena that do not occur in shallow engineering rock mass and pose increased engineering difficulty to effectively support the surrounding rock. A comprehensive study of deep surrounding rock support technology is, critical for establishing suitable techniques for mining deep rock mass

Methods

Discussion

Conclusion