Three-dimensional stress state in inclined backfilled stopes obtained from numerical simulations and new closed-form solution

Abstract

Backfill is commonly used world-wide in underground mines to improve ground stability and reduce solid waste disposal on the surface. Practical solutions are required to assess the stress state in the backfilled stopes, as the stress state is influenced by the fill settlement that produces a stress transfer to the adjacent rock walls. The majority of existing analytical and numerical solutions for the stresses in backfilled openings were developed for two-dimensional (plane strain) conditions. In reality, mine stopes have a limited extension in the horizontal plane so the stresses are influenced by the four walls. This paper presents recent three-dimensional (3D) simulations results and a new 3D closed-form solution for the vertical and horizontal stresses in inclined backfilled stopes with parallel walls. This solution takes into account the variation of the stresses along the opening width and height, for various inclination angles and fills properties. The numerical results are used to validate the analytical solution and illustrate how the stress state varies along the opening height, length, and width, for different opening sizes and inclination angles of the footwall and hanging wall. Experimental results are also used to assess the validity of the proposed solution.

A Strength Design Method of Cemented Backfill with a High Aspect Ratio

“…However, the research on the influence of these factors is still ongoing [3,4,35] and cannot be quantified easily in laboratory modelling and numerical modelling. And to assess the validation of the proposed method, numerical modelling was proved to be an effective way Advances in Civil Engineering 7 [2,11,12,21,33,[36][37][38][39][40][41]. To assess the stability of the backfill using 3D numerical simulations was proved to be effective [2,[28][29][30][31][32].…”

“…To assess the stability of the backfill using 3D numerical simulations was proved to be effective [2,[28][29][30][31][32]. Geometric and mechanical parameters used in numerical modeling were taken as typical values from previous studies [7,8,11,12,20,36,38]. typical values from previous studies [7,8,11,12,36,38]: unit weight c � 27 kN/m , Young's modulus E � 30 GPa, and Poisson's ratio ] � 0.25. e four vertical boundaries of meshes were constricted using roller support.…”

“…Considering the common two-step mining method of extracting and then backfilling, the cemented backfill body of first-step stope will have a free face when extracting the second-step stope. In a series of methods for designing the required strength of the filling body by the limit equilibrium method, the shear resistance force from lateral rock mass is a major concern in the process of evaluating the stability of the backfill body [10][11][12]. us, the lateral pressure force which contributes to the friction resistance has an important influence on the safety factor of the backfill body.…”

“…Sobhi et al [14] also pointed out that when calculating the lateral pressure, the active earth pressure state is more practical than the static earth pressure state which assumes a very large stiffness of the surrounding rock. e calculation of the lateral pressure of the filling body by taking the active earth pressure state is also adopted in [7,11,14].…”

Effect of Drainage and Consolidation on the Pore Water Pressures and Total Stresses within Backfilled Stopes and on Barricades

“…Over the years, much work has been conducted to assess the stresses in backfilled stopes through analytical solutions [20][21][22][23][24][25][26][27][28], experimental measurements [7,27,[29][30][31], and numerical calculations [32][33][34][35].…”