Advanced Materials Research Vols. 1030-1032

Abstract: An innovative external pre-stressed strengthening method, in which FRP (fiber reinforced polymer) sheet is placed outside of the concrete section and anchored in multiple-point, is based on moment of beam to change the area of section of FRP sheet along the length of beam. This strengthening method is that two ends of FRP sheet are first anchored by tightening WSGA (Wave-shaped-gear-anchor), then the FRP sheet is tensioned by tightening WSGG (Wave-shaped-gear-grip) on the middle of FRP sheet and accordingly pre-stressing force is built in FRP sheet. Two same 7m long reinforced concrete T-beams are strengthened at two sides of the beam with above strengthen technique, another same beam is strengthened with sticking CFRP sheet strengthen technique. Test results of strengthen beams indicate that this innovative external pre-stressed CFRP sheets strengthen technique could significantly improve the cracking load, yield load, ultimate load and stiffness of RC beams. The width of flexural cracks in concrete beams is effectively controlled and the strength capacity of the CFRP sheets is exploited.

Abstract: The wellbore friction, torque and drag, between drill string and the wellbore wall is the most important issue which limits the drilling industry to go beyond a certain measured depth. The calculation and analysis of torque and drag were considered to be very important in drilling and well design. A variety of models (soft, stiffness, mixed and finite element) have been used to determine the torque and drag. a FEA (Finite Element Analysis) model of the drill string to simulate it’s working behavior, involving contacts between the drillstring and borehole wall was developed, this FE Model was to be compared with computational model of torque and drag, and to be verified with experimental results. The drillstring displacements calculated by the FEA model matches those from commercial software in petroleum industry (Landmark). The model developed and discussed in this paper can be used for predicting torque and drag inside wellbores of oil and gas wells, and it will also benefit in preplanning simulation of oil and gas well drilling operations.

Abstract: The typical characteristic of stoning band coal seams is of multi-layers and low permeability, so fractured vertical well is usually used in the CBM development of this kind of coal seams. As far as the reservoir simulation of vertical fractured CBM wells is concerned, the fracture characterization technique is of great importance. Taking the vertical fractured pilots in F coal measures of Bowen Basin in Australia as an example, this paper will illustrate the application of fracture characterization technique in reservoir simulation. Its highlight is to scientifically characterize the shape of hydraulic fractures and quantitatively describe the reservoir permeability improvement after fracturing through “MULTX” of grid conductivity with Tartan grid model, thereby determining key parameters for the reservoir simulation of fractured vertical wells and providing a scientific basis for establishing CBM development plan and forecasting ultimate recoverable reserves.

Abstract: Suction caissons attract the attention as the foundation of offshore wind turbines. Installation and resistance behaviors of the suction caisson are important factors for the design of foundation. An installation behavior into sandy seafloor was discussed by using a model suction caisson and the failure surfaces in the aluminum rod mass, as the model ground, subjected to lateral force were compared. Consequently, the installation of model suction caisson into sandy sea depended on the permeability of sandy seafloor and lateral resistance of suction caisson depended on the dimension of suction caisson which affected on the shape of failure surface in the ground.

Abstract: This paper takes a 45+60+45m prestressed concrete continuous box Girder Bridge as background, based on “Specification for Inspection and Evaluation of Load-bearing Capacity of Highway Bridges” (JTG/T J21-2011), single beam model and solid model are built for schematic design of load test. Compare the measured value and the theoretical value, and evaluate the bridge bearing capacity, finally provide technical base for project checking and accepting.

Abstract: The cable tower is the bearing component of long-span suspension bridges, and its structure is very high and bear large force, which determines the stability and is the key of safety control. As for the height of the main tower of a long-span suspension bridge up to 195.3 m, the finite element software ANSYS is used to establish a three-dimensional finite element model (FEM), and the effects of geometric nonlinearity and material nonlinearity on the stability of the main tower are analyzed. The calculation results show that geometrical nonlinearity and material defects have significant influence on the main tower stability, and the nonlinear stability should be considered under wind load in the design calculation.

Abstract: As an important form of bridge foundation, caisson foundations are usually utilized based on the local geological and hydrological conditions. The static analysis is the main means to testify the reasonableness of the designing shape and size of caisson, but the dynamic analysis is usually ignored. To compare the anti-seismic difference between circular and rectangle caisson foundations, we use the software FLAC3D as the numerical simulation tool. By applying the seismic waves to the grid points at the bottom of the models, the time-history curves of acceleration, velocity, and displacement on the key points are obtained. From the results, we can draw the conclusions that when the cross-sectional area of the rectangular caisson is equal to that of the circular, the stability of the rectangular caisson is better than that of the circular.

Abstract: Based on the software FLAC3D, we set up the dynamic calculation model. By applying the horizontal (x direction) seismic waves at the bottom of the model, we simulate the earthquake action to the caisson foundation and the soil body around it and obtain the time-history curves of the acceleration, the velocity and the displacement of the key points in the model in x direction. We also obtain the rotation angle time-history curve and the relative displacement time-history curve of two key points at the bottom of the caisson foundation. Through the analysis on these curves, we know the maximum values of the acceleration, the velocity and the displacement of the top portion of the caisson foundation are 393.6 cm/s², 75.9 cm/s, 28.5 cm, and the maximum rotation angle of the caisson foundation is 0.08°. We sure the bond of the caisson foundation bottom and the below soil layer is firm and the relative displacement is only 1.3 mm. Looked from the overall,the anti-seismic property of the caisson foundation is good. The above results provide a reliable basis for the future research on the dynamic response of caisson foundation.

Abstract: Now, the extending of underground engineering was scarcely concerned. Through combining with engineering, the subside extending intersection construction process and supporting measure of underground cavities has been simulated based on building up 2D elasto-plastic FEM model. The stability of surrounding rock, stress and displacement field in extending construction are analyzed, and a few meaningful conclusions are presented. What has gained that served as scientific bases and technical guidance for underground cavities extending and reconstruction engineering.

Abstract: The computational fluid dynamics (CFD) is used to design the position of the inlet and outlet of the air conditioning and analyzing the air flow field and temperature distribution inside the operating room .The result showed the purification air conditioning of the mobile operating room can make air flow along only single direction with effectively avoiding the contamination gathering in the surgical area. It also can improve air cleanness of surgical area and fight against the infection of the patient wound. In the surgical area, the temperature is distributed around 23°C with perfect temperature distribution without obviously temperature gradient.