myGeobrugg
Systèmes
Année d’installation
2025
Situation de départ
The underground level geology consists of quartz–sericite metasomatites within weakened zones. The rock mass is heavily fractured, with fractures oriented in multiple directions. The drift runs along strike and, in places, across the main rock structures. The rock strength coefficient on Professor M. M. Protodyakonov's scale for the quartz–sericite metasomatites of the weakened zones is f = 7.1. The rock stability category is III (three). The likely causes of the rockfalls were the presence and opening of intersecting, multi-directional fractures in the roof and sidewalls, driven by weathering (rock fatigue) under aggressive conditions — mine ventilation and humidity — which led to rock collapse in this section.
Because the exposed area and cross-section have increased, the section has been weakened and lost its original stability, creating an ongoing risk of repeated rockfalls. The mine's primary support method is steel arches — slow and costly. Support of the test section was intended to trial MINAX mesh in combination with bolts as a reinforced combined rock-bolt support system for the mine.
Description
Works were carried out in a section with complex mining and geological conditions in the access drift leading to the ore drift. Blast holes for the rock bolts used at the mine were drilled with a Sandvik DD 311 drill rig using d = 35 mm drill bits, to an installation depth of 2.2 m. The bolts are installed in a fan pattern around the perimeter of the excavation (roof + sidewalls), with 1.0–1.1 m spacing between bolts in a row and 1.3–1.4 m between rows.
Bolt dimensions: L = 2.2 m, d = 22 mm.
Minax 80/4 high-tensile steel mesh was installed manually after each face advance cycle. Each time, the mesh was installed no more than 0.5–1.0 m behind the face area.
Pays / Région
Kazakhstan
Client
Ingénierie
Entrepreneur
Abyz Mine / Kazakhmys
Objet protégé
Carrière / Mines
Protection anticorrosion
galvanisé
Votre contact local
