Advanced Materials Research Vols. 255-260

Abstract: The seismic performance of reinforced concrete(RC) columns is one of the controlling factors of the shock resistance for RC frame structures and bridges under seismic loads. Due to the complicated material behavior and complex external force during the earthquake, an accurate simulation of the mechanical performance under seismic loads demands more precisions for the hysteresis constitutive laws of materials. In this paper, based on the fiber cross-section model, adopting revised Kent-Park model for concrete and Legeron model for steel reinforcement, programming the UMAT material subroutine, FEM software ABAQUS is used to simulate a RC column mentioned in a research. It’s results are found agreed well with the test results.

Abstract: According to the character that broken rock mass still has higher compressive strength with appropriate support action though it can not bear tensile stress and deformation character of board with different width-thickness ratios, an idea of keeping the stability of both sides of roadway with anchorage body was put forward, namely, the width(height)-thickness ratio of the anchorage body should be higher than that of the sheet. Thus the higher compression and shear strength can play the main role in keeping the roadway stable. A clear and definite theory for bolting support has been put forward, and the determination methods of geometrical and mechanical parameters of bolting support such as bolting strength, bolt length, spacing, interval of row and bolted length etc. have been deduced.

Abstract: The mine pressure behavior characters of shallow buried coal seam differed from both shallow seam mining and general depth seam. Mine pressure observation and numerical analysis were applied to research mine pressure behavior laws in fully mechanized face of shallow buried coal seam with thick bedrock and thin alluvium. It showed that the ground subsidence level phenomenon did not appear obviously although with obvious dynamic loading of fully mechanized face during the pressure period. The appearance was due to non-synchronized fracture from two key layers in the overlying rock layers and their interaction, which leaded to roof breaking initially and caving rocks with the form of an arch. Due to the periodic breaking and caving characteristics appearing as fully cut-down and arch alternately, the periodic pressure of shallow buried coal seam face showed as different size. The conclusion could be a reference for similar working face control.

Abstract: The gob-side entry retaining technology, one of the scientific mining technical system, can enhance coal recovery rate and reduce entry excavation quantity. However, only the effective entry-side support and the proper entry-in support could guarantee stability of the retaining entry undergoing mining influences of two working faces. In order to recover the section coal pillar between two working faces, the technology is applied in Qinxin coal mine. By using the high-water rapid hardening material as backfill material, the backfill pumps as transportation equipments of the material, the steel formwork and backfill bag as forming molds of the material, the entry-side support is of high support resistance, certain shrinkage, convenient construction. As for the entry-in support, the bolt support is designed to improve the bearing capacity and anti-deformation capacity of the surrounding rock, and the single hydraulic prop is adopted to reinforce roof support. The observation results show that the retaining entry keeps good performance. The case not only brings better economical benefit for Qinxin coal mine but also has referential significance for other coal mines.

Abstract: In order to compare with the seismic performance of tunnels in different soils, four cases are studied and analyzed in the current paper. Due to the different depth in the soil, the displacements of different part of tunnel are various in the earthquake. To compare the seismic performance easily, the inclination degree is chosen as the index. And the results show the inclination degree is smallest when the whole tunnel is all in the stiff soil. And the soft soil is able to enhance the inclination degree.

Abstract: Bored pile as a major type of foundation, during the construction process, hole collapse or weak air tightness of catheter leads mud layers or broken pile, which makes bearing capacity reduction or even complete loss leading differential settlement of building foundations. In this paper, two-dimensional simulation of the pile has been made by finite element analysis software ADINA. By using of large-scale numerical analysis software MATLAB, the data obtained has been fitted deriving empirical formulas, which researches how different thickness and depth of mud layers impact on bearing capacity of bored piles, having a certain engineering applications.

Abstract: Based on the deep foundation pit project of Wanbang Square in Qingdao, after many times numerical simulation of foundation pit with ADINA, the relationship conclusions were summed up by changing parameters of anchor rope and excavation step: The horizontal displacements of shoring structure became smaller by making the length of anchor rope longer or making the number of anchor ropes more or making the excavation step more; the uplift of the bottom of the foundation became smaller and the sedimentation of the surface became smaller by making the excavation steps more. It can offer reference to optimization of foundation pit supporting structural scheme.

Abstract: Along with the economical and the industrialization development, The development domain of rheology will be expanded. At present There are many researches about rock rheological, but the existing model Cannot completely, indication properties of rock, Especially the nonlinear rheological model and rock creep constitutive model of accelerating rheological phase of the study is scarce. After viewing a large number of the composition of rheological models and their laws in current papers, we find out what they are common and give the simplified method of creep equation and relaxation equation .Then we propose the inverse method to establish the new nonlinear rheological element model and the constitutive equation method. This paper focuses on establishing a new method of rheological model which provide technical support.

Abstract: Complicated occurrence situation of deep underground coal seams in China determines absence of a national rock classification index. Take Huainan mining area as an example, this paper aims to provide a practical method. It begins with a geo-mechanical assessment to check bolting feasibility of related rock mass. Once this is settled, roof self-bearing capacity coefficient and coal hardness coefficient which can comprehensively indicate basic characteristics of surrounding rock are integrated to classify the surrounding rock into four levels. Accordingly, stepwise bolting are provided according to dynamic combination of four basic bolting forms: super bolt assembly, cable bolt beam, high-pretension roof truss and metal chock plus grouting. An application case with rock Level III in Guqiao Mine, Huainan was introduced. Statistics show that bolt-based supporting is widely being used in more than 80% of Chinese coal mines with sound efficiency and applicability.

Abstract: According to the geological conditions of mine and mine’s surrounding construction, the geological mechanical model of explosion area and the structure model of surrounding civil architecture were established. Based on the monitoring blasting vibration result of mining explosion process, the dynamic response character and structural stress of surrounding civil architecture which have been caused by blasting vibration of mining were studied by means of the Finite Element Method (FEM) and the method of fast Lagrangian analysis of continua three dimensions (FLAC 3D). The results show that calculated results coincide with the monitor results collectively, and the influence caused by blasting vibration on the stress and strains of civil architecture is smaller. But at the civil architecture roof, the transient amplification acceleration caused by blasting is 25%.