The roof of the goaf is treated by the complete caving method. The track roadway behind the goaf of the 3313 working face is reserved as the return air roadway. The roadway behind the goaf is supported by a 3 × 3 × 1.4-m flexible formwork wall and anchor cable. The roof is mainly gray-black mudstone and siltstone.
In underground metal mines, goaf brings huge safety risks. It is an important part of mine to evaluate goaf stability and determine the best goaf handling measures. However, the evaluation and decision are often separated; they need to be unified. Meanwhile, stability evaluation and decision for goaf are a complex system engineering …
When there is a goaf at 8.68 m above the coal roadway, the distribution of deviatoric stress and vertical stress in roadway surrounding rock is shown in Fig. 7. Because the upper panels have been ...
The subsidence or collapse of coal mine goaf has a great impact on the construction of various large-scale projects and the environment, and can threaten the safety of people's lives. In the present study, CSAMT was used to detect coal mine goaf in China's Fangzi mine. Anti-interference data acquisition and processing strategies were adopted …
An inclined goaf caused by storage mining is a serious risk to subgrades and pavements. In this paper, effective investigation and detection methods of goafs were discussed considering the project of the Urumqi East Ring Expressway crossing the existing goaf of Z no. 2 mine. Moreover, by theoretical analysis and a series of field …
Generally, the water-bearing structures of coal mines mainly include coal seam, roof, coal seam, floor, and goaf, while the main water-conducting structures include faults, collapsed columns, and collapsed goaf areas. The most commonly used methods for the detection of the above structures include the seismic method, high-density electrical …
The mining process involves many complex problems, which are easy to cause environmental pollution and safety. The comprehensive geophysical exploration method combined with drilling method is used to carry out fine exploration of goaf. Firstly, the high density resistivity method was carried out, the data was collected by Wenner …
Spontaneous heating of coal continues to present a health and safety hazard in underground coal mines. The influence of seam gas composition on gas flow dynamics and distribution characteristics in the active longwall goaf has not been studied in-depth, and corresponding effective proactive goaf inertization strategies for preventing potential …
One added perk, Thomas said, is the easy access to tee times. The first tee at Augusta opens at 8 a.m. for practice rounds, he says, so if there's an afternoon storm or showers in the weather ...
Micro-seismic (MS) technique can be used to appreciate rock failure process and severity of damage by quantifying micro-earthquakes in terms of time, location, grade, and energy release. Based on 3D laser detection and high-precision micro-seismic monitoring, this study analyzes the MS activity, stress and displacement evolution linked …
Цохилтот бутлуур; Европ загварын цохилтот бутлуур; cs цувралын өндөр үр дүнт пүршин ко; Пүршин конус хэлбэрийн бутлуур; Шингэн даралтат конус хэлбэрийн б; …
This study comprehensively analyzes the safety and stability of old goaf under construction engineering based on specific projects using a variety of research methods. The Beijing Mentougou mining area is …
Published 24 May 2021. Abstract. Grouting reinforcement is one of the most effective methods to enhance the stability of the goaf, and its scheme selection, hole …
Evaluation of the stability of a shallow goaf in an open-pit iron mine is important for successful mining. Based on the idea of "rock disaster analysis and prediction combining field monitoring and numerical simulation," a modification of Mathews stability graph is proposed, and a monitoring scheme combing stress, displacement, and surface …
1 Introduction. Spontaneous combustion of residual coal in goaf is a fire hazard and is affected by many factors [1,2].As the mining depth and mining intensity increase, the initial temperature of the coal seam increases, especially in gassy and flammable coal seams, which increases the risk of spontaneous combustion of the goaf.
The Qi irons (as a 7-piece set) are priced at $1099 with steel (KBS Max MT 85) and $1199 (Fujikura Ventus Blue 7S, 6R, and 5A). The Qi10 HL irons are priced the same but with the stock steel shaft ...
Coal mining goaf is unconsolidated material formed by collapse of overlying strata. Water in goaf can flow into and contaminate surface water systems. An integrated geophysical investigation approach combining microseismic monitoring (MSM) and the opposing-coils transient electromagnetic (OCTEM) method was used to evaluate the …
forms of goaf voids. Figure 1. Measurement of voids in goaf. Based on the current research results, this article deÞ nes a void fraction as the ratio of a void s volume in goaf to its mining volume. The authors have put forward a concept of the overall distribution of a goaf void, deduced the theoretical formula, and calculated
To effectively improve the goaf stability, the optimal backfill parameters for the goaf treatment were obtained by a series of mechanical tests. The research results …
Longwall goaf project background is China Shandong blue ocean pilot e-commerce Industrial Park project. The data processing center is the "heart" of the e-commerce Industrial Park, the specific coordinates and the distribution of 9 # coal goaf in the data processing center are shown in Fig. 9. The data processing center with the …
At the same depth of the goaf, the oxygen concentration gradually decreases from the inlet side to the return air side; after the advancement distance exceeds 200 m, the air leakage in the goaf ...
The residual deformation of a goaf is studied to improve the foundation stability assessment for metro lines passing through the subsidence area of steeply inclined extra-thick coal seams. The variable mining influence propagation angle is introduced to describe the special form of the rock movement. Based on the modified …
The 47 groups data of mine goaf ground site were collected as learning samples. Five machine learning methods including decision tree, discriminant analysis, Support Vector Machine, and classifier ensemble were used to learn and test the data. The optimal algorithm was selected and the stability evaluation model was established to classify the ...
With the continuous improvement of infrastructure, some high-speed railway lines will inevitably cross the goaf ground, and there is less research on the safety of high-speed rail construction in goaf ground. To make a reasonable and accurate safety evaluation of the high-speed railway construction in the mine goaf ground, machine …
In recent years, more and more expressways have been built above the abandoned goaf. It is of great significance for safe operation of expressways to assess the instability risk of construction site above the abandoned goaf. In this study, a risk assessment model with seven main assessment factors is established for expressway …