Chock-shield support is usually used in undergroud coal mining to protect the roof. However, as the mining depth gets deeper, impact load that came from the roof becomes stronger and more frequent. This causes the support to bear a large number of dynamic loads, and reducing its reliability. To improve the support performance of the chock-shield support, the mixed-kinetic model was established using the mechanical-hydraulic co-simulation method. The load distribution law of the support joint under impact load form different stability forces, impact load amplitude, and impact frequency is discussed. The mechanical-hydraulic cooperative response of the chock-shield support are obtained. The results show that different joints show typical non-uniformity characteristic during the loading process. The proposed mechanical-hydraulic co-simulation method can more accurately obtain the dangerous points of hydraulic support reliability. The results of this study will help to improve the reliability of the chock-shield support.

With the increase of mining height, the problem of coal wall spalling in the working face gradually worsens. Hydraulic support and its face guard structure are the key pieces of equipment to restrain the coal wall spalling. However, at present, the hydraulic jack is mostly considered as rigid in the analysis of protection mechanism. This simplification cannot effectively reflect the true bearing state of the face guard. In order to improve the accuracy of analysis, this study considers the face guard jack as a flexible spring and establishes a rigid‐flexible coupling analysis model of the face guard mechanism. First, based upon the multibody dynamics software ADAMS®, the multibody numerical model of the face guard of the hydraulic support was established. The influence of the two kinds of structures on the coal wall disturbance was analyzed and compared. Then, the rigid model was meshed. The hydraulic jacks were equivalent to the spring system, and the rigid‐flexible coupling model was established. Based upon the application load on different positions of the rigid‐flexible model, the load‐bearing characteristics and hinge point force transfer characteristics of the two face guards were analyzed. The results show that the support efficiency of the integral type was higher than that of the split type. In the vertical support attitude, the dynamic disturbance of the coal wall, produced by the two kinds of face guards, was small. The four‐bar linkage effectively improved the ultimate bearing capacity of the integral face guard. The results provide theoretical support for the design and optimization of the face guard.

This paper examines the internal rectangular loading problems for an elastic halfspace where the shear modulus varies exponentially or linearly and the Poisson’s ratio keeps constant or varies linearly with depth. The numerical method is developed through applying the fundamental solution of layered elastic solids and integrating numerically it over the loading area. The adaptive integration of the displacement and traction integrals over the loading area is designed to calculate the nearly singular integral for the source point close to an element. The discretization approach is applied to deal with an arbitrarily depth-heterogeneous elastic solid. OpenMP directives are used to parallelize the internal loop, which controls element iterations so that a high computing speed can be obtained. For an axisymmetric internal loading problem, the displacements obtained with the present formulation are in a very good agreement with existing closed-form solutions. Finally, stresses and displacements in non-homogeneous halfspaces induced by horizontally and vertically uniform rectangular loadings are presented. Results illustrate the effect of non-homogeneous properties on the stress and displacement fields.

The paper examines the elastic fields of displacements and stresses for a nonhomogeneous elastic half‐space where the elastic parameters have a linear variation over a finite depth beyond which it is constant. The circular loading area is subjected to a uniform inclined load. The numerical method is developed by applying the fundamental solution of a layered elastic solid and integrating numerically it over the loading area. As a result, only the loading area needs to be discretized in using the proposed numerical method. Numerical examples of calculation of displacements are conducted, and excellent agreement with the existing closed‐form solutions is obtained. The results obtained are used to understand the elastic fields induced by different types of loads in a nonhomogeneous medium.