Advanced Materials Research Vols. 594-597

Abstract: After the excavation of the rock , the rock mass stress state changes and the quality of rock mass damage deterioration. Rock excavation of spillway tunnel of the hydropower station may have some influence on the stability of the tunnel-face side slope. In this paper, combined with the engineering practice, based on the unloading rock mass theory and through two dimensional finite-difference method. Selected seven feature points near the excavation surface as monitoring points for calculation ,then calculated the effect on the stress and strain of the slope caused by the excavation of the spillway tunnel and analysed the changes in the distribution of the slope rock mass plastic zone and the point factor of safety. The results show that spillway tunnel excavation in excavated slope have some impact on the excavated slope stability, and it is more obvious for the effect on stability of excavated slope in considering rock mass unloading effect than do not consider the rock mass unloading effect.

Abstract: Based on study on the existing calculation method of bearing capacity of combined-pile composite foundation，consider the behavior of loaded combined-pile composite foundation and the general influence of construction method to the bearing capacity of soil, two coefficients, soil bearing capacity exertion coefficient and soil bearing capacity improvement coefficient, are introduced，a new step-by-step calculation method of bearing capacity of combined -pile composite foundation is put forward.It shows that computed data is in agreement with experimental date of loading test by example project．

Abstract: To explore support technical problems in deep soft rock roadway, according to deep complicated geological conditions in 102 transport rise of Yuandian Mine, obtaining deformation characteristics of roadway in the initial support scheme under conditions, analysing the reasons of instability and failure of surrounding rock, proposing the surrounding rock control technology of step-by-step strengthen co-supporting, determining secondary anchor cable strengthen support time and grouting delay distance, optimizing the parameters of roadway support. Industrial practice show that the control effect of deformation was obvious,which provide the reference for deep soft rock tunnel support decision.

Abstract: The stability of the soil slopes can be judged according to the critical moisture content and the actual moisture content when the soil slopes be in the limit equilibrium state. From the perspective of earth pressure, the critical moisture content is the moisture content when the soil slopes be in the active limit equilibrium state, at this time, the active earth pressure is 0. The critical moisture content can be determined and the stability of the slopes can be judged according to the relationship of the soil parameters and the moisture content and the active earth pressure being 0. The critical moisture content of the upright or declining cohesionless slopes can be determined according to the relationship of the internal friction angle and the moisture content. The critical moisture content of the upright cohesive slopes can be determined by solving the equation of the critical moisture content. For the declining cohesive slopes, first, the cohesive soil having the cohesion and internal friction angle is replaced by only having the equivalent internal friction angle of the cohesionless soil according to the principle of the equal strength, then, the critical moisture content can be determined according to the relationship of the equivalent internal friction angle and the moisture content of the declining cohesionless.

Abstract: In view of highway slope stability problems, this paper puts forward the method that numerical modeling of the road slope by the finite element analysis software —ADINA, with the Gravity Loading Proportion Methodto calculate the slope stability coefficient, deeply research the development process of deformation, breakage characteristics and stability of road high cutting slope. Comparison with the results obtained by the strength reduction FEM proposed by AcademicianYingrenZhengshows that the proposed method is more simple and reasonable to determine slope stability or not.

Abstract: Huai’an salt mining industry exploitation is introduced in this paper. We analysis the problems and influence factors of geological environment, such as rock-salt cavity roof collapse, the pollution to environment, brine leak and based on huai’an geological structure and the current method of rock salt mining process. In the analysis, the reasons due to the problems is be shown in details. We put forward the corresponding suggestions and countermeasures of prevention and control according to these geological environment problems as the references for related engineering design, construction, operation and environmental protection of the local salt mining enterprise and Huaian bureau of land and resources,. and so on.

Abstract: Two reinforced concrete core wall models with large height-width ratio were built and tested to failure under the combined action of constant axial load and reversed cyclic lateral load. The span-depth ratio of coupling beam on each core wall was focused on. This paper presents the results, including failure mode, hysteretic behavior, load-carrying capacity, ductility, energy dissipation ability. With the span-depth ratio of coupling beam dropping from 1.7 to 0.9, stiffness and load-carrying capacity of the specimen had risen markedly, but the ductility performance dropped significantly. It can be seen that the span-depth ratio of coupling beam having important effect on the seismic behavior of reinforced concrete core wall.

Abstract: The steel roof of main palaestra of the World University Games is a long span space structure of single-layer fold face reticulated shells. The space positioning installation of members of this structure is very difficult, and the control accuracy is very high. In order to improving the installation accuracy of this space structure during the construction, a method named bulk-way assembly technology at high altitude with multi-points supporting had been adopted. After the closure of the steel roof structure the temporary supporting jigs began to be uploaded. During this process the supporting jigs quit work gradually and the main structure began to carry the load. Different uploading way will make different influence for the main structure and supporting jigs during the uploading process. These have to be considered in the structural design and construction stage. This article adopts construction mechanics and FEA method to analyze the uploading procedures according to the real construction process in order to finding the actual internal force and deformation and ensuring the security of the structure and supporting jigs. Lots of results have been obtained as guidelines in theory for the design and construction.

Abstract: A simplified 3D multi-degree-of-freedom (MDOF) model for estimation of seismic response of reinforced concrete wall-frame structures with uniform stiffness along the height are proposed in this paper. This model is aimed at reducing the computation demand in the nonlinear response history analysis (RHA). By employing the continuum technique for the structure and adopting the bilinear hysteretic model for material properties, the procedure for the development of a simplified MDOF model, called continuum MDOF model is developed. The proposed continuum MDOF model is shown to provide a simple and efficient for computation of nonlinear response of tall wall-frame structures.

Abstract: The stress of the grain steel silo is complex. Recently, many grain silos scraped during their service life. The results of finite element analysis by COMSOL show that the cause of the structure failure is the stress concentration caused by the expanding of the hole. Analysis on different hole on the wall of the silo and different frame to strengthen the hole was also studied. Considering the impact of the weight of the structure, the pressure and friction force caused by the storage of the grain and wind load. The analysis turn out that, if the frame of the hole is identical, the stress level and the first principal strain in condition of circular hole is lower than that of rectangular condition, and the maximum vertical displacement of circular hole is smaller than rectangular. In addition, if the hole is the same, the stress level and the first principal strain in condition of U-shaped frame is lower than that of square condition, but the maximum vertical displacement U-shaped frame is bigger than square frame. Therefore, we can’t reduse the stress level by strenthening the frame.