Advanced Materials Research Vols. 446-449

Abstract: As to shield tunneling, that soil is reinforced into the void is one of the most important reasons which cause the ground settlement, and always most important factor in the tunnel construction and the relative research. The numerical simulation studies presented in this paper focus on the different grouting pressure causing different ground settlement, plastic area and stress growth behavior. Based on the simulation results and the engineering ground settlement limit, propose reasonable synchronous slurry injection pressure and the relative method of controlling ground settlement. Propose reasonable suggestion for the determination of grouting pressure during shield construction.

Abstract: If TBM does the excavating work in jointed rock mass, the cutterhead may be jammed. In order to decrease the loss, it is necessary to carry out risk evaluation. Whether the cutterhead is jammed or not depends on the relationship between torque and resistance torque. The magnitude of resistance torque depends on height of collapse, so according to the randomicity of height of collapse and probability theory, a formula for calculating the probability of cutterhead jamming is established. Meanwhile, according to the magnitude of resistance torque and cutterhead’s parameters, consequence of cutterhead jamming is divided into five ranks. Based on probability and consequence ranks, risk evaluation matrix for TBM’s cutterhead is proposed. The research results are demonstrated logically by the calculation of practical engineering.

Abstract: Taken the excavation of TBM assembly underground chamber with deeply buried super large and complex section in Jinping Ⅱ Hydropower Station as the background, apply theoretical analysis and experimental method to study the rock deformation and displacement analysis. The result shows that, drilling and blasting method is used for construction which is divided into four layers from top to bottom according to the excavation, they are 8.5m, 5.5m, 6.0m,7.0m from top to bottom, respectively. the displacement of surrounding rock generally moves toward the direction of the free surface. The rock possesses spring back deformation pointing to internal underground chamber. The displacements of arch crown and floor are mainly vertical, and displacement of retaining wall is mainly horizontal. This is significantly different from the rock deformation of underground chamber under general stress after excavation. The chamber displacement distribution under high crustal stress is closely related to stress direction. Location axis of underground chamber should parallel the direction of maximum principal stress. Under the complex and great deeply buried condition, excavation of large section tunnel by digging from the top layer can better release the rock stress, and the rock displacement changes gently, which is conducive to rock mass stability and structure security.

Abstract: According to the specific engineering examples, the detailed analysis of the lining crack damage in process, status, characteristics and the distribution of disposal has been done. Based on the exploration and analysis of construction process and topography and geology factors , this paper discusses the genesis of lining crack , establishes the numerical model in lining cracks section taking the real topography condition, structure parameters of surrounding rock, the actual construction sequence,etc. Focus on the principal stress distribution law in lining structure and collapse deformation of surrounding rock, this paper explaines the cracks mechanism in theory, and the results is consistent to the actual practice.

Abstract: For numerically simulating the phase change of water in ground freezing process, a correct method is proposed in this paper, that the unfrozen water content in frozen soil is taken into account to calculate the enthalpy value at different temperatures. A calculation example of a cross-passage project in shield tunnel shows that the thickness and the average temperature of the frozen wall calculated by this method are very close to the in-situ monitored data. Based on this method, by comparison of the development rate of thickness and the average temperature of the frozen wall according to different design plans, the ground freezing scheme for the cross-passage is optimized for the shortest duration of freeze in agreement with the work standard. The study could enlighten the design for similar projects in the future.

Abstract: In this paper, aiming at the problem of “market failure” in the building energy-saving field, we discuss the principle of externality in this field and analyze how the externality of building energy-saving leads to the rent-seeking behavior of building energy-saving products manufacturers or developers using the economic theory. Based on the Game theory, we analyze the revenue and cost of unproductive activities between building energy-saving regulation department and building energy-saving products manufacturers or developers, how the government supervises and regulates corruption which comes from unproductive activities, and the tripartite game model of the rent-seeking behavior in the domain of energy-saving is built. On the basis of the establishment and solution of the tripartite game model，we put forward effective countermeasures and methods for government re-regulation.

Abstract: The thin plate penetration test method was presented by Professor T.S. TAN for the determination of undrained strength in high water content sludge. Based on the method, a thin plate penetration test device is designed. Through the thin plate penetration indoor test of dredged sludge, the unload weight and interval time of this test method are studied. The results shows that: if the water content range of soil sample can be segmented, and determine the appropriate interval time for unloading in each segment of the water content range, the efficiency and accuracy of thin plate penetration test method can be improved.

Abstract: All previous earthquake damage show earthquake damage of the buildings on the slope is serious than the buildings on flat ground, so it is important to analyze of the influence of slope terrain on characteristics of horizontal and vertical ground motion response spectrum. The horizontal and vertical seismic elastic responses of 28 viscoelastic rocky slopes by white noises excited, with height of 10m to70m and slope of 15°to 60°, are calculated by numerical finite element analysis method. The influence laws of height and degree of slope on horizontal and vertical ground motion response spectrum and response spectral ratio are analyzed. The distribution laws of the corresponding period of the maximum of response spectral ratios are contrasted. The maximum of amplification factor of design horizontal and vertical ground motion for structures on rock slopes are given to be the references to code for seismic design of building structures.

Abstract: This article introduces a new type of steel plate damper with transverse slits. The damper mainly consists of a few parallel core plates, a top plate and a bottom plate. The core plates are made of mild steel with a series of transverse slits in the centre. The damper mainly utilizes plastic bending deformation of the core plates to dissipate energy for vibration control of civil structures. Main performance parameters of the damper are studied through theoretical analysis. Mechanical properties of the damper are analyzed through finite element method (FEM). Finally, an experiment of the damper is conducted to verify the hysteresis performance of the damper. Results of the investigation indicate a better use of the core plates due to the transverse slits. The damper exhibits good energy dissipation capacity and ductility through the experiment.

Abstract: For floating system cable-stayed bridge, the longitudinal displacement of stiffening girder and moments of towers are very large when strong earthquake happens. Too large displacement of stiffening girder leads to collision between girders of the main bridge and the approaches. Using spatial finite element model and time history analysis method, the seismic responses of cable-stayed bridge are studied considering the elasto-plastic effects. The results show that the displacement of stiffening girder is very large when no seismic reduction measures are adopted. The viscous dampers installed between the stiffening girder and towers can efficiently reduce seismic responses of the cable-stayed bridge. Especially, the displacement of stiffening girder can be controlled well to meet the design requirement. Using the optimum parameters of damper, the height of pier under tower and intermediate supports in side span on seismic responses are studied in detail. The longitudinal displacement of stiffening girder increases with the pier height increasing. The intermediate supports in side span are benefit for seismic reduction.