G. N. Khan

Discrete element modeling of rock failure dynamics

The discrete element method is employed to study rapid failure of a test rock specimen under cylindrical tensile wave effect. The author proves the effect exerted by the mechanical characteristics of rocks and the boundary conditions of the problem on the length and shape of fractures, and compares the experimental evidence with the calculation data.

Enhancement of load-bearing capacity of ground anchors with flexible tendon

The effect described by the Euler formula for a flexible line being under tension and wrapping around a rigid support is experimentally proved to implement in the case of a nonrigid support being a ground base. Model and field experiments show essential rise in the load-bearing capacity of ground anchors with flexible tendon—E-anchors, owing to this effect. Equipment for installation of the anchors is designed and trialed. Using DEM, a 2D problem on the efficiency of the new anchors as a function of direction of pull out force applied to the tendon is solved. The E-anchors are supposed to be promising for the application in construction and operation of engineering structures.

Estimation of depth and dimension of underground void in soil by subsidence trough configuration based on inverse problem solution

The authors offer an approach to estimating parameters of underground voids formed in soil under natural or induced forces. Irreversible deformation of soil is modeled using discrete element method. The formulated inverse problem on geometry and occurrence depth of a void by the data on configuration of the subsidence trough has a single-valued solution.

Mechanism for generation of peak load on under-bin feeders at processing plants

The authors use physical and DEM modeling to analyze stresses and strains in broken ore discharged from accumulating bins using an apron feeder. It is substantiated that the determinant of the peak load on the feeder and the discharge unit is dilatancy. It is shown that the absolute value of the peak load is conditioned by physico-mechanical characteristics of discharged ore, structural design of a discharge unit and deformation constraint. The article demonstrates possibility of upgrading one of conventional schemes of discharge unit and shows prospects for new designs.

Rotary ground anchors with flexible pull bar: Interaction with ground

The article describes design and installation of rotary ground anchors with flexible pull bar, reports in situ and laboratory research as well as discrete element modeling results, and discusses kinematics of load bearing slab and the force interaction of the anchor and ground.

Relation between High Tectonic Stresses and Endogenous Ring Structures

Horizontal compression stresses are anomalously high at mineral deposits in the continental areas of the Earth. Many mineral deposits occur within subsurface ring-shaped structures. The authors reconstruct stress in a ring structure at a representative stage of its evolution. It is shown that lateral compression in the ring structure, in particular, at mineable depths, is very heterogeneous, unstable and can considerably exceed stresses due to overburden. The calculation results are compared with the laboratory and field data.

Peak loads on feeders in gravity reclaim stockpiles of broken rocks

Actual physical models and discrete element method are used to analyze stress-strain state of broken rocks at the moment when an apron feeder starts discharge from floor storage. It is shown that conventional designs of discharge units of floor storages fail to eliminate broken rock dilatancy which is a determinant of the peak load on the feeder at the moment of its actuation. Based on the investigation results, the authors propose an approach to filling floor storages with broken rock and a structural layout for the storage discharge unit. The offered engineering solutions enable preventing from dilatancy-induced impact on stress state of broken rock being processed and, as a result, elimination of peak loads on feeders.

Modeling of the discharge of free-flowing materials from hoppers

The possibility is substantiated for modeling gravitational flow of free-flowing bulk materials during discharge. Parameters are determined which provide dynamic similarity of the model to real conditions that are confirmed by experiment.