山东省劳动力结构对经济结构转型升级的支撑研究

在经济新常态背景下,山东省经济发展的着力点由速度转向结构,必须依靠经济结构转型升级才能持续健康发展。经济结构转型升级需要相应的劳动力结构支撑,重视劳动力结构与经济结构的匹配和协同发展,是经济可持续发展的重要前提。基于山东省第三次经济普查数据、山东省统计年鉴以及第六次人口普查数据,应用灰色关联度方法和支撑度模型综合评价山东省及其17个地级市之间的劳动力结构对经济结构转型升级的支撑能力,可以发现:(1)依据钱纳里的经济发展阶段理论,判定山东省正处于经济结构转型升级的关键时期。(2)劳动力结构的各个因素对经济结构的影响存在着明显的差异性,从山东省经济结构转型升级视角来看,劳动力供给需要增加劳动适龄人口数量、提高劳动参与率、增加城镇人口比重和大专及以上就业人口比重。(3)当前和今后一段时间内,山东省及其17个地级市的劳动力结构能够支撑其经济结构的转型升级,但17个地级市的劳动力结构对经济结构的支撑度差异显著,据此将17个地级市分成三个类型区,并针对每个类型区的特征给出分类指导意见。

Stability assessment of rock surrounding an I-beam supported retreating roadway

The installation of a back-wall guard-board is the key to successfully supporting underground retreating roadways in coal mines. Based on the coordinate support principle, and using an I-shaped steel support for the surrounding rock, a mechanical model was developed for the stability of the roadway support and surrounding rock. Analysis of the bearing capacity of the roof back-wall guard-board and modelling of the equations for the maximum deflection and the maximum compressive stress of the top and side beams of the I-shaped steel support were undertaken. Simultaneously, the model was used to calculate and analyse the stability of the top and side beams of the I-shaped steel support structure and analyse the criteria for their stability. The results provide a reliable theoretical basis for the judgment of the stability of the surrounding rock and support structure. The theoretical evaluation results are consistent with field data. Finally, the key support parameters of the top and side beams of the I-shaped steel support structure and the variation of the maximum deflection and the maximum compressive stress as affected by the influence of the guard-board length were investigated. It is concluded that, as the back-board length increases, the maximum compressive stress in the top beam of the I-shaped steel support increases while the compressive stress in the side beam decreases. The results show that the accuracy of judgment of the stability of a supported retreating roadway is improved, providing guidance for the design of such typical I-shaped steel support and back-board structures.

Computation model of proppant embedment depth based on dimensional analysis

Hydraulic fracturing is designed to form a high-conductivity fracture. The proppant will embed into the formation rock, especially in soft rock, owing to the interaction between proppant and fracture surface after fracture closure. Proppant embedment would reduce the fracture width and then lower the fracture conductivity. According to dimensional analysis, the rock is assumed to be an elastic material. Using the theory of elasticity to describe the stage of elastic deformation and analysis of the corresponding simplified embedding process, the study establish the static computation model of the two-dimensional infinite half plane and three-dimensional infinite half space model of the proppant embedment. According to laboratory results, the calculation model was modified, got an effective correction factor and analyzed the causes of errors, then discussed the factors which have impact on proppant embedment. The result calculated by the model in this paper can be reference of prop- pant optimization in on-site fracturing for a certainty degree.