Reinforcement mechanisms of rock bolt - a laboratory investigation


Author : Mohd For Mohd Amin, Khoo Kai Siang & Chai Hui ChonPublication : Bulletin of the Geological Society of MalaysiaVolume : 46Page : 101-105Year : 2003


Description

Bulletin of the Geological Society of Malaysia, Volume 46, May 2003, pp. 101 - 105

 

Reinforcement mechanisms of rock bolt - a laboratory investigation

MOHD FOR MOHD AMIN, KHOO KAI SIANG AND CHAI HUI CHON

Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor

e-mail: mohdfor@fka.utm.my

 

Abstract: The use of rock bolts as rock reinforcement is becoming more popular in Malaysia. However, its effectiveness depends on a number of factors especially with regards to the technique on how the bolt is installed. Its reinforcement mechanism also restricts its application for certain modes of instability and types of rock. This paper highlights a laboratory investigation on the reinforcement mechanisms of rock bolts, specifically on bolt inclination, anchorage type and level of pre-tension. The investigation was conducted using a physical model of a rock bolt intersecting a joint. Results obtained show that a better reinforcement can be obtained if bolt is inclined at an angle so that it elongates upon joint displacement. Full-bonded bolt is more superior in terms of mobilising the anchorage capacity and consequently, this allows for immediate utilisation of the reinforcing element. Pre-tensioning of bolt induces clamping effect on joint surface consequently, helps to reduce joint dilatation and increases the inherent shear strength of the joint.

 

Abstrak: Penggunaan bolt batuan sebagai kaedah pengukuhan batuan semakin popular di Malaysia. Walaubagaimanapun, keberkesanan kaedah ini amat dipengaruhi oleh beberapa faktor terutama yang berkaitan dengan teknik pemasangan bolt. Mekanisme pengukuhan kaedah ini juga menyebabkan penggunaannya terhad pada jenis batuan dan ragam kegagalan tertentu. Kertas kerja ini membincangkan satu kajian makmal ke atas mekanisme pengukuhan bolt batuan khususnya, mengenai kesan orientasi bolt, jenis ikatan dan tahap pra-tegangan. Kajian dilaksanakan menggunakan satu model fizikal bolt batuan yang bersilang dengan satah kekar. Keputusan kajian menunjukkan tahap keupayaan pengukuhan meningkat apabila bolt dipasang secara condong dan mengalami pemanjangan apabila berlaku anjakan pada kekar. Bolt yang diturap sepenuhnya lebih baik dari segi menggerakkan keupayaan pengukuhan oleh yang demikian, kesan elemen pengukuhan dapat dimanafaatkan serta merta. Pra-tegangan pada bolt dapat mengaruhkan kesan pengapitan pada permukaan kekar dan ini dapat mengurangkan dilatasi dan meningkatkan kekuatan ricih kekar.