## 1 Introduction  
The stability of rocks is an important subject in rock and slope engineering [1]. Strata and surface movements induced by mining activities in an open-pit final rock slope could trigger slope failure and surface subsidence, creating safety risks to the mining workers. It is thus important to study mining-induced strata and surface movement for better improving the understanding of the stress transfer mechanism in the rock slopes, so as to apply appropriate engineering mitigation measures to prevent and reduce disasters associated with the mining-induced slope failures. In the literature, the methods of investigation can be broadly categorised as theoretical analysis, numerical simulation and physical modelling. Most of the existing theoretical analysis idealises the strata as a beam or slab, which is then analysed by various mechanical analysis methods. A commonly-used mechanical model is, namely, the compressive arch theory. For example, [PERSON] and [PERSON] applied the discontinuous deformation analysis to investigate the formation of pressure arch [2]. [PERSON], [PERSON] et al. used the compressive arch theory to predict collapse of deep-buried tunnel [3]. On the other hand, [PERSON] et al. used the cantilever hypothesis to analysis the mechanism of strata movement and surface deformation in an iron mine [4]. [PERSON] et al. conducted a research on the failure of a gate road system based on the cantilever hypothesis [5]. [PERSON] et al. determined the static stress within fault-pillars using the Voussoir beam theory [6]. [PERSON] and [PERSON] found and defined three kinds of structural model affected by the key strata's position in super great mining height long wall face [7]. Although the mechanism of mining-induced strata movements can be reasonably captured by using the existing theoretical methods, idealising the strata to be a simple solid beam or slab would lead to an inaccurate estimation of rock mass deformation, especially under complicated geological settings, where a simple beam or slab geometry would be insufficient. With the development of the numerical simulation method, it has been widely used to study underground mining-induced strata and surface movement [8; 9; 10; 11; 12; 13; 14]. By numerical simulation, the stress, strain, and displacement of strata could be conveniently analysed, but on account of the constitutive relation and mechanical parameters of rock mass are difficult to be defined accurately. Physical modelling, on the other hand, has a major advantage over the theoretical method, as a carefully designed physical model can reproduce the deformation and failure mechanisms of the strata induced by mining under a more realistic geological conditions [15; 16]. Two-dimensional (2-D) physical models with simplified geological condition have been constructed [17], but there are only a few attempts to model the strata behaviour three-dimensionally, especially when the strata in the prototype has complex joint systems. Existing 2-D or three-dimensional (3-D) model tests considered only the major structural planes, such as the fault plane and bedding plane. Any widely-distributed joints within the rock mass are normally ignored or highly simplified [18; 19; 20; 21; 22]. Indeed, the presence of rock joints and their complex distribution typically control the mechanisms of rock mass deformation and strata movement caused by mining. When the rock mass is free from joints or relatively intact, the failure mode of the strata caused by mining is usually collapse or topographic avalanche [23]. On the contrary, deep subsidence pit (up to 100 m) was formed when rock mass is composed of complex joint systems, and a series of ground fractures were also observed at the upper part of eastern final slope (see Figure 1 for an example found at the open-pit slope of Yanqianshan iron mine). Thus, a physical model that could properly and realistically capture the rock joint distribution and orientation is necessary to more correctly study the effects of rock joints on strata and surface movement.