Applied Mechanics and Materials Vols. 351-352

Abstract: Distributed optical fiber sensor for temperature and strain identification as the basis, the optical fiber sensor has advantages to monitor deformation and seepage in the embankment dam relying on its long distance and continuous monitoring ability. Taking layout of layered installation, the relationship between laying bending radius and the strain of the optical fiber sensor is studied. Indoor simulation test and local outdoor dam model test show that, the distributed optical fiber sensor for dam defect monitoring has good effect and application prospect. The embankment dam model provides experimental platform to further study early warning criterion of impending disaster in embankment dam.

Abstract: The low strain method has the advantages of simple, fast detection is widely used in the pile testing. The low strain method was presented to pile test on a communication hinge engineering of China Mobile Group Gansu Co.,Ltd. The basic theory, tesing method of pile and judgment standard about the ultrasonic wave method are analyzed.

Abstract: As for implementing functions in slope online monitoring system by exploiting data acquired via GPS, good and high efficient stored procedures are essential. More importantly, a good designed stored procedure can simultaneously provide decision services for multiple users. By integrating the Client/Server and Browser/Server subsystems, this system explores a much convenient and automatic way to manages the mining area. 18 database tables are designed to support the database operation, such as the GPSSTATICRESULT table that storeds accurate static data and the STATIONINFO table that records all equipment information. Moreover, the design and implementation of stored procedures is analysed to flexibly support complicated system functions. The results indicate that system working with stored procedures has high performance on applications open-pit mine. The results not only confirmed the applicability and effectiveness of stored procedures, but also revealed system with stored procedures has advantages of conveniently managing mining data, timely sending real-time monitoring information, optimizing security of mine production and making auxiliary decision for enterprise.

Abstract: With the increasing height of building, high-rise building structure selection becomes more and more important. This paper presents the application of genetic neural network method to study high-rise building structure selection and uses the MATLAB neural network toolbox with a combination of genetic algorithm toolbox to develop a genetic neural network expert system for high-rise building structure selection to make the selection process simple.

Abstract: In order to explore detecting function for grouted density and empty hole ofcorrugated pipe, the paper proposes a method. Firstly, detect groutedcorrugated pipes and concrete (avoiding corrugated pipes) using elastic wave,judge defective corrugated pipes through comparative analysis of the data.Secondly, detect the defective corrugated pipes using ultrasonic wave, analysisthe test data, determine the specific location and size of defect in corrugatedpipes. Finally, verify by actual design. The result shows that judged locationand size of the empty hole are consistent with the actual situation. So it isfeasible to detect grouted density and empty hole of prestressed corrugatedpipe with the method. So as to provide theoretical guidance for grouteddetection of corrugated pipe.

Abstract: The foundation pit of Jinan West Railway Station Ground is vast in area and large in Excavating depth and closely adjacent to the high-speed railway buildings and subgrade, therefore the foundation pits deformation is strictly controlled. The foundation pit supporting design applies a comprehensive mode by combing soil nailing wall, compound soil nailing wall and bored cast-in-situ piles with anchor cables. Monitoring has been carried out on internal force of side slope and supporting structure throughout the excavation of foundation pit, so detailed monitoring data have been acquired. It has been acquired, by contrastively analyzing, that since the foundation pits displacement volume may reach about one half of the final displacement volume at the time when its excavation is completed, with a huge rate of change, supporting should be timely completed during the excavation period. Compound soil nailing wall can reduce side slopes horizontal displacement volume about 25~30% , compared with soil nailing wall, and effectively add the rigidness of side slope, however it is not very useful for settlement; We get utmost horizontal displacement volume at one third to two fifths of pile length, so it is advised to increase density and strength of anchor cables.

Abstract: Concrete deformation measured under a certain condition in the experiment are very different from those in practical engineering structures, therefore, its necessary to monitor concrete properties in structures. In the paper, by real-time continuous monitoring of reinforcement concrete slab prepared with expansive agent, time-dependent temperature variations and strain variations are obtained and analyzed, and indoor test of the mechanical properties and deformation of field sampling from the slab are presented, so that this completes a transition from the specimen in experiment to the structure in engineering. The result shows that: there was no early-age crack in the four month after casting; the temperature had a certain increase due to heat generation of cement, which can lead to shrinkage deformation in cooling period; the temperature fluctuate with ambient temperature and there are obvious peak temperature rise about 15°C; There was a certain expansion at heating period, which can be considered as compensating shrinkage caused at late age in a certain extent so that minimum strain value is just about-120με which are not beyond the ultimate tensile strain. In addition, the measured experimental data can provide helpful reference for early crack control and durability of concrete structure, and they can also be use to verify and improve the accuracy of the numerical results for slab, which is available in the future for basis to similar projects and research.

Abstract: A new kind of embedded acoustic emission (AE) sensor has been developed and it was made up of 1-3 cement-based piezoelectric composites. Compared with those sensors which were traditionally affixed to concrete structures, the embedded AE sensors could minimize the leakage of AE hits and improve the accuracy of data acquisition. The AE thresholds of the sensors are 45dB and they can perceive the position of source and crack extending areas in concrete. Because of the low operation cost, the admirable compatibility with concrete and the excellent durability, the sensors could be widely used in the monitoring of civil structure.

Abstract: One long-span bridge adopted the cantilever casting method, which is pre-stressed concrete variable cross-section continuous box girder structure. In the construction process, due to the concrete pouring, hanging basket moving, construction loads, pre-stressed tension, concrete shrinkage and creep, temperature, humidity and many other factors. There will be such problems of cantilever beam segment closed error and the bridge line-type do not coincide in design goals. In this paper, we use the bridge dedicated finite element program MIDAS / Civil procedural for modeling and structural analysis. Analyze the problems of deflection control and pre-camber adjustment of cantilever construction, in order to ensure that the bridge closure smoothly in accordance with the design standards.

Abstract: A high-rise building with an 11 meters thick raft foundation will be built in Shenyang, which will bring a huge challenge to construction on site. To avoid temperature crack affecting construction quality, a comparative study of model test and numerical analysis about temperature monitoring are carried out to determine the construction measures for the mass concrete mat foundation. The results show that the development of temperature field of inner concrete can be divided into three stages: growing rapidly, cooling fast and cooling steadily. Different temperature control measures should be used for different temperature developing stages. The results of the model test and numerical analysis in the paper will provide technical supports to the temperature control on site.