Wyniki wyszukiwania - BazTech

1

Optimizing the Width and Compressive Strength of Artificial Protective Pillar in the Mining of Medium-Thick Coal Seams in Quang Ninh Using the Numerical Model

Bui Manh Tung, Dinh Van Cuong

Inżynieria Mineralna

|

2023

|

no. 2, vol. 1

143--154

EN

Currently, in many countries with the coal mining industry, the technology of using artificial pillars has been successfully applied to replace coal pillars to protect the entry gate road, thereby reducing the rate of resource loss, as well as the cost of entry gate road, and mining costs. However, in order to optimize the required width and compressive strength of artificial pillars with thickness, slope angle and mining depth, more detailed studies are required for each specific geological condition. This research uses Phase 2 numerical simulation software to analyze the stability of artificial protective pillar of the roadway prepared in the mining of medium-thick coal seams in the Quang Ninh coal region (Vietnam). The research results show that the relationship between the width of the artificial pillar and the slope angle follows the rule of a linear function. The size of the artificial protection pillar increases according to the mining depth. When the mining depth is 350m, the size of the pillar changes from 1.0 ÷ 2.4m, and to 1.4 ÷ 2, 8m at a depth of 500m. When the slope angle increases, the required pillar width also increases. That is due to the fact that at a large slope angle, the pressure acting on the pillar is not at the center, but deflects to the side adjacent to the entry gate road that needs to be protected, the compression force is not distributed evenly. The required compressive strength of the artificial pillar varies according to the condition of the slope angle, when the seam slopes 10°, the required compressive strength is from 8 to 12 MPa, when the slope angle increases to 20°, the required compressive strength of the pier increases to 18 ÷ 28 Mpa, but when the slope angle increases to 35°, the required compressive strength of the pillar tends to decrease to 16 ÷ 17 MPa. Thus, when operating in the corresponding conditions, it is necessary to choose the size and required compressive strength of the artificial pillar to ensure the working capacity of the pillar.

2

Fracture Mechanism of Hard Main Roof and Determining the Width of Coal Pillars when Extracting Flat-lying Coal Seams

Le Quang Phuc, Dao Van Chi, Nguyen Phi Hung, Vu Thai Tien Dung

Inżynieria Mineralna

|

2023

|

no. 2, vol. 1

271--280

EN

In underground coal mining, the stability of roadways and gob-side entry depends on the coal pillar width. An unreasonable width of the coal pillar will cause the roadway to be in a dangerous zone of influence of the abutment pressure, leading to severe roadway deformation. This paper studies the fracture mechanism of the hard main roof and reasonable coal pillar width to protect the stability of gob-side entry driving. The research results show that when mining a coal seam under a hard main roof, the console of the main roof on the edge of the coal seam has the form of hinge structure. The great load of the roof layers and the rotation of the console are the main causes leading to the variation of the stress field in the coal seam. According to the development law of the stress field, after the main roof completes the collapse process, the peak of the maximum stress will move deep into the solid coal seam, and on the edge of the coal seam it will form a low-stress zone. Research results from the case of Seam #11 of Khe Cham coal mine, Vietnam show that the gob-side entry will be well stabilized when the narrow coal pillar between it and the boundary of the gob is 4–5 m.

3

Study on the possibility of using artificial pillar to replace the protection coal pillar of the preparation roadways during the mining process at underground coal mines in Quang Ninh region, Vietnam

Cuong Dinh Van, Thanh Tran Van, Tuan Nguyen Anh

Inżynieria Mineralna

|

2019

|

R. 21, nr 2/2

192--198

EN

The coal reserves in protection pillar of roadways are expected to be left in the mining process in underground mines in Quangninh coal basin which is relatively large (about 16% of the total reserves). If it can be exploited, it will help to save non-renewable coal resources, reduce the cost of preparing roadway meters, extend the mine life and increase the efficiency of construction investment. In the world, in order to reduce coal loss in protection pillar of roadways, mining technology to exploit and use artificial protection pillars are quite popular. Accordingly, in order to simultaneously exploit coal in the protection pillar and maintain the transport roadway as a ventilation roadway for the longwall in below level, the post-mining coal pillar will be replaced by artificial pillars formed from the stone backfill cribs, columns, metal cribs, chemical materials or low-grade concrete mortar mixes formed from fly ash, bottom ash of thermal power plants, combined crushed waste rock and a cement additive,... This paper will evaluate the possibility and propose a number of mining technological scheme as well as the type of construction materials suitable for artificial columns.

4

Mosty zespolone na dźwigarach INP

Karaś S., Jukowski M.

Drogownictwo

|

2018

|

nr 1

13--23

PL

Pierwszą polską normą do mostów zespolonych była PN-EN 1994-2:2010. Mimo to, w latach 60. do 80. zbudowano wiele mostów zespolonych na dźwigarach INP, które funkcjonują do dzisiaj. Kilka z tych obiektów zostało omówionych w artykule.

EN

The first Polish standard for composite bridges of steel-concrete was the PN-EN 1994-2: 2010. Despite this, in the time between the 60s and the 80s, many composite bridges were built on the INP girders. They still have been in operation. Several of these objects have been discussed in the paper.

5

Stan naprężenia według modeli filarów 3D I 2D

Hałat W.

Prace Naukowe Instytutu Geotechniki i Hydrotechniki Politechniki Wrocławskiej. Konferencje

|

2005

|

Vol. 75, nr 41

205-212

PL

W pracy przedstawiono wyniki numerycznego modelowania (mes) filarów międzykomorowych złóż rud miedzi. Stan naprężenia wyznaczony został dla przestrzennego modelu filara - model 3D oraz dla modeli płaskich - 2D. Na podstawie ilorazów wartości składowych stanu naprężenia wynikających ze sposobu modelowania pokazano "o ile różnią się wyniki" gdy filary odpowiadające warunkom przestrzennym zostaną rozwiązane jako zagadnienie płaskie. Przyjęto, że model przestrzenny jak i modele płaskie filarów zbudowane są z tego samego materiału skalnego podlegającemu temu samemu prawu fizycznemu.

EN

In the elaboration, results from numerical modelling (FEM) of barrier pillars in underground copper mine were presented. The stress field was calculated for 3D and 2D models. On the basis of the quotients of stress components, which arise from the way the models are constructed, it has been shown "how much the results differ from each other" when the real three-dimensional pillars are considered as a planar one in the calculation procedure. It has been assumed that both the models are made of the same rock and are subjected to the same physical law.