Rock support is the basis of any underground mine and many open cut operations. Ground support methods have evolved over the years with the current trend to use bolts, mesh and shotcrete. In the last decade there has been a significant growth in the number of commercially available thin spray-on liner (TSL) products. It is a common opinion that TSL products, as part of a complete ground control system, may present significant benefits for operations. Numerical modeling techniques are regularly used for research and design purposes. It can be effectively applied in the field of geomechanics in order to assist in the interpretation and prediction of results. The bending and the double-sided shear tests are the two laboratory tests that are designed to evaluate the properties of different TSLs. This paper evaluates the use of numerical modeling to simulate the material properties and support action of TSLs. The purpose of this study is to further develop modeling techniques for the simulation of TSL materials. This paper discusses the methodology and results of simulating these laboratory tests using the FLAC finite difference modeling software.
A Thin Spray-on Liner (TSL) is a polymer based liner that is sprayed onto the rock surface, generally at a thickness of 3 to 5 mm. It effectively bonds the surface of the rock together and acts as a seal between the rock and mining environment [1]. TSL products were developed in the early 1990’s for rock support applications [2]. They have been used in civil engineering for many years and it is a growing support concept still lacking widespread application in the mining field [3].
Although the support action of TSLs is not well understood, quick application with high areal coverage enables early reaction against ground movement. They have the potential to allow for greater extraction efficiency with reduced safety concerns. The use of TSLs has been common in the mining industry but widespread application is still missing [2, 4]. Therefore it is important to develop standard testing procedures to understand better the support mechanism of TSLs.
The defining properties that make TSL products useful as surface support are their high tensile strength, shear strength, adhesive strength and rapid curing time. Numerical modeling is an accepted technique for solving problems across a wide range of applications and fields. According to [5] these numerical models allow us to understand the complex mechanisms and predict their behavior within the scope of the model.
Dealing with complexity
Access to results that are typically not measurable
Flexibility
The main advantages of numerical modeling that benefit the research process are discussed in the review of geotechnical engineering modeling by [6]:The reliability of modeling also requires consideration. Mathematical models differ from other types of models in that they are not tied to any physical form. While this gives greater flexibility it also makes them more abstract than their physical or analogue counterparts. A “mathematical model can only be good as our understanding of the processes” [7].
