Effects of weathering on stability with respect to carboniferous limestone quarry faces

• Main Author: Roubos, Vassilis
• Published: University of Sheffield 2012
• Subjects: 622.3516
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578055

Until recently, there were two types of man-made rock slopes: civil engineering and mining / quarrying related. The factors differentiating these two slope types are relative life span, safety requirements and construction cost. For civil engineering slopes, these requirements are high, whereas for mining slopes they are usually lower. The tightening of UK/EU environmental legislation has created a third category of rock slope: the quarry faces produced by or remaining after the end of the extraction operation in Areas of Outstanding Natural Beauty and National Parks. Such slopes have life spans and safety requirements similar to civil engineering slopes but with the construction cost of mining and quarrying slopes. Due to the fact that a considerable amount of time may elapse between the end of the extraction operation and a quarry's potential or intended after-use, quarry operators want to know what will happen to the faces if they remain free of conventional support methods. Consequently, the aim of this project is to asses the impact of weathering agents on the stability of different types of Carboniferous Limestone quarry faces in the Peak District National Park, UK. Two methodologies were followed. These comprised: firstly, in situ monitoring of the stability of selected quarry slopes and secondly, accelerated weathering tests on rock samples collected from the monitored slopes, and measurement of some of their mechanical and physical properties. Only cost-effective techniques that could be readily employed by the quarry industry were used. From comparison of the resultant data, the main conclusion is that, in contrast to the findings of published research into the rate of weathering of rock materials, Carboniferous Limestone rock faces at the sites studied do not display a linear decline in their mechanical and physical properties due to weathering processes. Rather, they either display no significant alteration or an alteration following a concave trend, with an initial decline and subsequent increase in their properties. This means that their stability does not deteriorate at a constant rate over time. The implications of this for the selection of appropriate restoration methods are discussed and some alternative strategies are proposed.