Conveyance vibration results from guide misalignment
Shaft steelwork is subject to lateral dynamic loads generated by vibration of the conveyance as it travels in the shaft. The vibration is generated by misalignment of the steel guides that the conveyance travels along.
Historically design procedures did not consider dynamic effects, leading to unexpected steelwork failures
Historically, shaft steelwork was designed to resist a static lateral load equivalent to 10% of the conveyance mass, irrespective of the conveyance speed. This was successful in many shafts, but there were instances where forces very much higher this were encountered, due to the dynamic interaction between the conveyance and the steelwork. This phenomenon became known as “slamming”. Slamming may lead to static overload or fatigue failure of shaft steelwork and conveyances. In one instance steelwork failures resulted in closure of a shaft for several weeks whilst steelwork repairs were completed.
COMRO design guideline results in rational analysis allowing for dynamic effects
The South African Chamber of Mines Research Organisation, COMRO, embarked on extensive research into dynamic performance of conveyances, culminating in a design guideline document “Design Guidelines for the Dynamic Performance of Shaft Steelwork and Conveyances”. This document is the basis of South African National Standards for shaft steelwork and conveyance design and is called up in Australian Standards for the design of shaft steelwork and conveyances (AS3785).
The design approach recognises the influence of parameters such as conveyance speed, guide and bunton stiffness and guide misalignment on the lateral forces, and provides a rational approach to predicting these forces, ensuring that steelwork designs perform reliably.
SKM engineers participated in development the design guidelines
SKM engineers were involved in the COMRO research program including leading roles in directing and managing the research effort, undertaking in-shaft performance measurements for validation purposes and development of guide misalignment measuring devices. Consequently SKM has strong background in the design and analysis of shaft steelwork and conveyances.