Applied Mechanics and Materials Vols. 204-208

Abstract: The stability control of surrounding rock is a relatively important problem in tunnel boring machine (TBM) construction. The tunnel convergence deformation value was monitored in field while TBM passing weak and broken section of hydraulic tunnel. The correlation between tunnel convergence and surrounding rock stability is analyzed. The monitoring results show that: the characteristic of weak and broken Strata is closely correlated with some geological conditions, such as fault development, intrusive contact of orthophyre and lamprophyre veins. These supporting measures can well ensure the stability of surrounding rock in weak and broken section, such as sealing the inverted arch by using concrete of C25,reinforcing the inverted arch by steel arch of I10 and anchor construction in the roof. There is great difference between the properties of the weak and broken rocks on both sides, which is the main reason of the large tunnel convergence deformation. The monitoring results can provide reference for similar engineering in the future.

Abstract: First order iterative algorithm, mixed iterative algorithm, structural damage identification using static and dynamic data were put forward. The first and second order sensitivity matrixes of modal parameters that respect to the damage member were derived, and the modal truncation error which produced during the derivation of modal mode sensitivity was improved. The first and second order sensitivity equations were established respectively based on the principle of Taylor series expansion. And the solving method of these sensitivity equations was studied. Mixed iterative algorithm took up the second order nonlinear analytical solution as the first substituting value, and then the first substituting value was modified based on the Taylor series bias error using the solution of the first order sensitivity equation. It showed that the mixed iterative algorithm in this paper had a better convergence and a faster iteration speed because the higher precision second order nonlinear analytical solution was adopted. Because the method using static and dynamic data combined the static information and dynamic information of the structure, it could react the inside information of the structure more comprehensively, the result of damage identification was more accurate and it would be adapted more widely.

Abstract: The vault settlement, the horizontal convergence of Fangdoushan tunnel are monitored and measured. The changing curves with time are drawn; while the data of convergence measurement is analyzed with linear regression. The whole constructing process is simulated to analyze based on FLAC3D. The results of comparative analysis of the data from field monitoring and the data from numerical simulation shows that the simulation results accord well with the actual monitoring data, which will furthermore optimize both the design and the scientific construction

Abstract: Seismic checking of panel zone for steel frame is very important in seismic checking of steel structure. This paper starts with the comprehension of new seismic design code of 2010, and the calculation formula of shear strength and yield bearing capacity for the panel zone is derived when the beam height in two side of joint is unequal, resorting to current Design Code for the Steel Structures and Seismic Design Code for Buildings. The formula is utilized for an engineering example in this paper, and it can provide some references for the design of steel structure.

Abstract: The assessment method of load carrying capacity for concrete rectangle section simple beam subjected to fire was presented. Comprehensively considering influencing parameters, load carrying capacity for reinforced concrete rectangle section simple beam was analyzed in a fire hazard by using numerical simulation program. A series of safety assessment regularities for the reinforcement pieces was put forward subjected to fire. The studied results indicate that: the ultimate moment for reinforcement concrete beam bridge tends to decrease linearly after 40 minute, the fire resistance of the reinforcement concrete rectangle section simple beam increase linearly with the increment of the concrete cover thickness; Therefore, the increment of concrete protective thickness is effective to fire resistance and safety grade for the reinforcement concrete beam.

Abstract: This paper mainly discusses one kind based on the 3G network technology cluster type tunnel safety monitoring system. Tunnel safety monitoring center of the system can be displayed at the same time, analysis of bridge and tunnel safety monitoring status, is convenient for decision makers to different budgets, optimize the overall regional tunnel cluster maintenance; through the cluster type tunnel safety monitoring, can be realized on the spread over a larger area of bridge and tunnel security state data of horizontal comparison, unified management, completely changed the previous single tunnel safety monitoring system to realize the information sharing between the" information island" situation, more convenient to the regional environment, similar or different environment, different structure tunnel similar structure tunnel safety status of the longitudinal, transverse analysis comparison and research, which is beneficial to promote the optimization of tunnel structure design and implementation of a number of tunnels, the maintenance and reinforcement.

Abstract: In this paper, the near-field multi pulse earthquake wave is generated by means of combining the velocity pulse component and the broad-band component based on studying the characteristics of the near-field ground motion.. Then, have made a numerical analysis on the composite isolated structure’s dynamic response as well as a quantitative analysis towards its energy dissipation with the help of the energy equation. Study shows, by comprehensively making good use of the energy dissipation characteristic of the laminated rubber bearing and the viscous damper, the viscous damper can perfectly find its way of taking its energy dissipation advantage, thus , to reduce the displacement of the isolation layer, and then improve the force state of the structure , accordingly decrease the damage to the upper structure. All in all, it has made a great contribution to improving the security of the structure under the near-field multi pulse earthquake.

Abstract: Externally bonded FRP for strengthening concrete structures is widely used in concrete structures strengthening field. Many factors affect the strengthening quality, in which delaminations and air voids are two especially important factors. At present the most popular method of inspecting delaminations and air voids is hammer sounding, but this method is slow, the inspection result is easily influenced by the inspector’s experience, and the defect area can’t be measured accurately. In this paper infrared thermal imager is used, according to the inspection results with infrared thermal imager in different conditions, the influence factors to the inspection effect including surface infrared radiation rate, wind, heat source type, heating time and the test environment are analyzed. The research shows that under right conditions using infrared thermal imager to inspecting the delaminations and air voids is a convenient, quick and accurate method.

Abstract: Considering the effect of time, rainfall and temperature on slope deformation, deformation factors and expressions were deeply analyzed. Statistical regression model of slope deformation was established by Matlab software and stepwise regression algorithm, thus slope deformation can be regression analyzed and predicted. Through analyzing the deformation monitoring data of a hydropower station spillway left high slope, the result showed that statistical regression values of slope deformation are in good agreement with measured values, multiple correlation coefficients were good and the residual standard deviations were small. This model can reflect slope deformation and trend. It provided guidelines to analyze on security status and prediction of deformation trend with great practical value.

Abstract: On the basis of truss-and-arch model and the concrete softening strength criterion under ultimate state, a formula for shear capacity of reinforced concrete (RC) beam with diagonal reinforcement was established and verified. Accordingly, six RC beams with diagonal reinforcement and corroded stirrup were tested along with control group, the tested results were analyzed by liner regression to modify the formula given. Hence a formula for inclined section shear capacity of stirrups corroded RC beam with diagonal reinforcement was proposed and compared with a preceding formula without a consideration of diagonal reinforcement in corroded RC beam .The results showed that the existence of diagonal reinforcing steel bars enhanced the behavior of vertical compression web member in truss institutions, therefore increasing the shear force shared by truss mechanism. The inclination of diagonal web member is a crucial parameter of truss model. As the stirrup corrosion aggravating, the shear bearing capacity of such RC beams does not decrease drastically.