Advanced Materials Research Vols. 250-253

Abstract: There are different blasting stress field which around the blast hole caused by different charge when explosives exploded in the rock. Simulation analysis on borehole wall pressure and explosion stress field of rock at different charging structure was done by ANSYS/LS-DYNA. The simulation results indicate: stress of coupling charge is the maximum, water-decouple charge is the latter and air-decouple charge is the minimum; and whether air-decouple or water-decouple charge, peak stress value of model decreased along with the increasing of decouple coefficient, but the air-decouple charge show more obvious. Therefore, water-decouple blasting has good energy utilization.

Abstract: Small pipe of staggered by length leading-drilling and grouting support technology was adopted for per-reinforcement of Lion-shaped Tunnel typeII rock, cement paste filled into loose rock mass rock fracture for adglutinate broken rock into a integrality, thus enhance the coherence and solidity of rock. Thesis introduced process flow of small pipe drilling grouting, grouting equipment, grouting parameters selection and practical applications. Through tunnel deformation monitoring and analysis, grouting reinforcement has achieved very good effect.

Abstract: Rock bolt crane girder is a structure form which is widely used in the underground powerhouse of hydropower station. It makes reinforced concrete anchored in the underground powerhouse rock using anchor rod, and makes the reinforced concrete, anchor rod and surrounding rock work together to resist the load. Stability has been a common problem in the realm of engineered construction. This article will analysis the stability of the rock bolt crane girder in a underground powerhouse of hydropower station by using the traditional rigid body limit equilibrium method and the finite element method, and give several destroying forms. The results show that the rigid body limit equilibrium method is flawed, need to be corrected; In overload cases, the contact surface of girder and rock crack, it turns the damage to the bottom O point at the end; When it is simulated by the strength storage method, the crane girder's shear yield slips the damage along the base.

Abstract: The 15 tunnels located in Line Chengkun, Baocheng and Dacheng were investigated by the authors. The tunnel disease was inducted and summarized, and the main disease forms and diseases reasons were analyzed.The five measures ( improve the compactness, control and reduce the initial crack, improve the toughness, reduce the second stiffness and mist curing) are proposed, and can improve the durability of the tunnel lining proved by large number indoor concrete test. The authors hope the results of this paper benefit design and construction.

Abstract: A series of large scale consolidated drained shear triaxial tests were performed on reinforced and unreinforced sand-gravel specimens, the peak strength and residual strength characteristics of reinforced and unreinforced sand-gravel specimens were compared. The results show that: the peak strength, the residual strength and cohesion of reinforced sand-gravel are higher than unreinforced specimens, and is related to the characteristics of geotechnical grille used in this study. However, adding geotechnical grille has less effect on maximum volumetric strain and internal friction angle of sand-gravel.

Abstract: Cemented coarse-grained soils have both the properties of coarse-grained soils and concrete. This paper used discrete element method (DEM) to simulate of the drained monotonic load triaxial tests of coarse-grained soils and cemented coarse-grained soils respectively, the microscopic parameters of numerical models were calibrated based on the tests. The characteristics of the cemented coarse-grained soils and the microscopic mechanism were analyzed. The results showed that, the cemented coarse-grained soils have the higher modulus and strength compared with coarse-grained with adding the 3% cement in the specimens and appear the significant strain softening after the stress reaches the peak value; the deformation of the soil particles,the friction between soil particles and the crack of the cement bond are the mainly internal factors.

Abstract: The arches resist general loading by a combination of axial compression and bending actions which vary along the arch. Under these actions, an arch may suddenly deflect laterally and twist out of the plane of loading and fail in a lateral-torsional buckling mode. This paper investigates the lateral buckling strength and design of steel arches under general loading. It is found that the subtended angle and load distribution significantly affect the lateral buckling strength of a steel arch. The rules for designing steel beam-columns against lateral buckling cannot be used directly in the design of steel arches against lateral buckling under general loading, because they do not include the effects of the subtended angle. The buckling loads of arch with different load condition, subtended angle, manner of laying section are calculated by finite element method. The interaction equation against lateral-torsional buckling for steel arches subjected to combination of bending and axial compressive actions is proposed. The safety and applicability of the interaction equation is verified by parameter analysis.

Abstract: With 19 groups of data associated with inrush or bursting water from karst cavity, obtained from Yichang-Wanxian Railway Maluqing Tunnel field test, conceptual models of Karst Water Burst Flood (KWBF) was brought forward by statistical analysis and phenomenological induction. KWBF is super-large amount of artesian water together with mud, which statically deposited in karst cavity, suddenly released into tunnel. KWBF has 3 kinds of characteristic: large scale of cavity water, high hydraulic pressure, high bed load content, dynamic supply of ground water, strong destroyed power; no foreboding, paroxysmal and intermittence, antinomy between paroxysmal and arrearage; force majeure, difficulty forecast, etc. Forecasting of Karst Water Burst Flood is conducted with rainfall seeping theory and statistical analysis method, while the base data are obtained from field quantity observation technical such as rainfall, hydrograph measure. Because of pressure dispersion between inside and outside of the cavity, seepage enlarge is evolved into conflux so that deprive groundwater from aquifer aqueduct and fracture, so, the water together with mud release suddenly from karst into tunnel. The key effect factor on KWBF is water count and silted or filling degree of conflux aqueduct. It is the essential numerical criterion that the daily rainfall must be less than 20mm if construction in the tunnel after the karst cavity has been broken through. To evade risk during construction temporary stage and permanent working stage, measure of energy releasing and pressure reducing (ERPR) must be accept. In addition, it was suggested that the key parameter of risk control for karst tunnel is water count and its cumulating velocity, mechanics characteristic of bed load filling in the conflux aqueduct.

Abstract: In the civil engineering construction, with the building load of building construction or adding storeys, foundation pit dewatering, embankment filling , over time, the pore water stress that is borne by pore water in the foundation decreases gradually, the effective stress that is borne by particle increases gradually, the foundation bearing capacity increases gradually, we use different methods to derive the variation law in the theoretical solution, and carry on the comparison, then get the same conclusion. By using theory to solve the frequently encountered problems during civil engineering construction, including the problems of building construction or adding storeys, foundation pit dewatering, embankment filling, it provides theory basis for both economical and safe civil engineering construction .

Abstract: This paper presents the results of seismic behavior analysis of a multi-span simply supported (MSSS) bridge in Qinghai-Tibet Railway. The main goal is to examine the effects of frozen soil condition and wave passage on seismic behavior of MSSS Bridge. A 2D FE model was established by ANSYS software in order to evaluate the effects of modeling, in which bearings and pounding effects were also considered. Results indicate that frozen soil condition has an important effect on the seismic response in longitudinal direction; wave passage can influence the seismic response of MSSS Bridge within a certain range of seismic wave travelling velocity.