ABSTRACT

In coal mining industry of Vietnam the open pit method makes up about 70% of product.. All of open pit mines in our country have problems with slope failure. Studying factors causing failure of slope and designing measures for stabilizing them is an important rock mechanics problem. In this paper author introduces some typical geomechanical schemes and some geological sections, the most prevalent types of mine slope deformations and some basis factors influenced on stability of mine slopes. Some measure for their stabilizing are mentioned.

RÉSUMÉ

Au Vietnam, I' exploitation des mines de coquille a ceil overt occupy d' environ 70% de production. Chez nous, touts les mines à ceil overt ont les problems de glissements des talus. L' etude des facteurs de glissement des talus et la conception des mesures de stabilisation des Falus sont lesproblems importants de la mecaniqu des roches. Dans cet article, I' auteur presente quelques plans geómecaniques, les types de deformation les plus repandus des talus de mines, les facteurs fonclamentaux qui influencent à la stabilisation des Falus. Quelques mesures de les stabiliser sont aussi presentees.

ZUSAMMENFASSUNG:

In der Vietnamesischen Kohlenbergbausindustrie betragt die Produktion der offenen Mineschopfueng ewe 70%. Ale offense Kohlenbergwerke in unserem Land haben verschiedene Probleme mit der Störung (Abfallung) von Gefalle. Die Untersuchung verschiedene Faktoren, die zu einer Störung von Gefalle der Kohlenbergwerke fuehren, und das Projekt der Maßnahmen zur ihren Stabilisierung sind wattage Probleme in Giblet von Gesteinsmechanismus in unserem Land. In diesem Bericht möchte der Autor ionize geologische mechanistic Scheme und typist geologische Schmitt, eying typist Deformational der Gefalle der kohlenbergwerke und die basischen Faktoren, die auf die Stabilisierung von Minesgefalle einflueßen, beschreiben. Einige Maßnahmen zur Stabilisierung von Gefalle der Kohlenbergwerke sind auch hier angefuehrt

INTRODUCTION

The annual coal output of Vietnam is about 7 million of tons and it is to be increased to 10 million of tons in the year 2,000. During the excavation the initial stress state has been changed, so many slope failures occur. Following (table 1) is some main data. It is obviously from table 1 that failures occur at small depth (average 50–70m). The deeper mine slope is the more active slide will be. Some slide in Cao Son mine, South foot wall slope of Coc 6 mine, foot wall slope of Ha Tu mine is being stabilized. Some others are still active.

I - GENERAL DESCRIPTION OF MAIN GEOLOGICAL SECTIONS

Most of mines in Vietnam is situated in three main areas deferring in geological features. Bac Thai areas, Quang Ninh and Na Duong areas. Quang Ninh zone is the biggest an d the most complicated. Coal bearing deposit consists of gravelit, sandstone, siltstone and mudstone of Trias age (T3nr). The periodical stratigraphy is rather clear. In each period of stratigrafication - from down up- grain size decreases from gravelstone to sandstone, siltstone and mudstone. There are weak layers of coal-mudstone above and under coal seam. There are 21 periods in Quang Ninh, 12 periods in Bac Thai and 9 period in Na Duong coal area. Quang Ninh deposit is located in tectonically active area, so it is divided by a lot of tectonic faults folds of all kinds. Inclined angles of rock layers are usually between 20–35°, some above 50–70° and decrease in direction far away from fold axis.

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