Research Article Experimental Study on Low-Strength Similar-Material Proportioning and Properties for Coal Mining Shaojie Chen, 1,2 Hailong Wang, 1 Junwen Zhang, 3 Huilin Xing, 2 and Huaiyuan Wang 1 1 State Key Laboratory of Mine Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao 266590, China 2 Centre for Geosciences Computing, School of Earth Sciences, Te University of Queensland, Brisbane, QLD 4072, Australia 3 School of Mining Engineering, Heilongjiang University of Science and Technology, Harbin 150022, China Correspondence should be addressed to Shaojie Chen; csjwyb@163.com Received 14 May 2014; Revised 19 November 2014; Accepted 20 November 2014 Academic Editor: Guocheng Lv Copyright © 2015 Shaojie Chen et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Similar-material simulation test is an efective tool to study the practical problems in mining and civil engineering. Tis paper conducts an orthogonal study on low-strength similar materials comprising sand, fy ash, and plaster and analyses the sensitivity of the materials. Te mechanical properties of the similar materials strongly depend on the proportioning ratio, and they can satisfy diferent similar-material simulation tests. Te compression strength and elastic modulus of the similar material decrease as the sand-binder ratio or cement ratio increases. Tere are approximately linear relations between the compression strength/elastic modulus and sand-binder ratio and approximately power relations between the compression strength/elastic modulus and sand- binder ratio. Sensitivity analysis employing the range method shows that the efects of the cement ratio on the compression strength and elastic modulus are more obvious than the efects of the sand-binder ratio. Finally, one of similar materials is used in a simulation test of coal backfll mining. 1. Introduction Some large-scale projects, such as the underground coal mining that reduce the strength of the strata and are subjected to deformation failure, are difcult to study on-site. Although these complex problems can be investigated through theoreti- cal analysis and numerical modelling, most problems need to be investigated by conducting geomechanical simulation tests [1–5], such as similar-material simulations. A geomechanical simulation test is the representation of real physical objects, with the materials having mechanical properties similar to those of a prototype according to a certain proportionality relation. Te model has all or most of the major character- istics of the prototype, and an experiment can be duplicated using the model in less time and at lower cost, and visual results can be obtained. To obtain results that are more convincing, the selected similar materials must have very similar physical and mechanical properties for the physical model and engineering prototype [6]. Te materials and mixing ratio strongly afect the properties of the physical model, which is critical to the success of simulation tests. With the help of similar-material simulation test, Gao et al. studied the time series system for induced caving of roof in continuous mining under complex backfll in ore body number 92 of Tongkeng Tin Mine [7]; Li et al. simulated the “domino efect” of the stope pillar unstable failure of gently inclined and medium thick phosphate rock under pillar and room caving [8] and the deformation behaviour of overburden rocks and mining pressure of the deep ore body of mining [9]. Moreover, Meguid et al. conducted physical modelling of tunnels in sof ground using a mixture of barite powder, sand, plaster powder, water, and liquid laundry detergent [10], and Fei et al. employed a temperature-analogue material to simulate the decreasing strength of the weak interlayer but did not obtain desired results [11]. A new similar material mixed using sand, barite powder, talc powder, cement, Vase- line, and silicone oil for fuid-solid coupling was developed by Li et al. to simulate the tunnel under Qingdao Kiaochow Bay in China [12], and the efects of the sand-binder ratio, binder proportions on similar materials of limestone was Hindawi Publishing Corporation Advances in Materials Science and Engineering Volume 2015, Article ID 696501, 6 pages http://dx.doi.org/10.1155/2015/696501