Advanced Materials Research Vols. 594-597

Abstract: In order to solve the problem on sensor optimization placement in the structural health monitoring (SHM) field, a new sensor optimization method is proposed based on the modal assurance criterion (MAC) and the single parenthood genetic algorithm (SPGA). First, the required sensor numbers are obtained by using the step accumulating method. The SPGA is used to place sensors, in which the binary coding is adopted to realize the genetic manipulation through gene exchange, gene shift and gene inversion. Then, the method is further simplified and improved for higher computation efficiency. Where, neither the individual diversity of initial population nor the immature convergence problem is required. Finally, a numerical example of 61 truss frame structure is used to assess the robustness of the proposed method. The illustrated results show that the new method is better than the improved genetic algorithm and the step accumulating method in the search capacity, computational efficiency and reliability.

Abstract: The wireless sensor network is a highly active area of research. Much progress has been made in wireless sensor network research for structural monitoring, but the research of the long-term monitoring system based on wireless sensor network in civil engineering structures is still at the beginning stage. The paper proposed to use wireless sensor network to realize intensive measurement long-term monitoring, in order to improve the effect of structural health monitoring. It introduced the characteristics and deficiencies of the wireless technology application in the structure health monitoring system, and proposed the system design principle of the densely measured points long-term monitoring system based on wireless sensor network. We has carried on the detailed argumentation and design from system architecture, the terminal node, monitoring method three aspects, and put forward a set of solutions.

Abstract: The water seeping from dam foundation often contains dissolved matter from the seepage channels. The deposition of the dissolved matter will easily block the monitoring instruments. To solve this problem, a sewage device in seepage monitoring instrument for dam foundation is designed. Several experiments on the capacity of the sewage device on sewage flow conditions are set. The results of the experiments proved that the sewage device for dam foundation seepage monitoring instrument is feasible to reduce the precipitates.

Abstract: Experimental data was collected for structural identification (St-Id) of an old bridge: (1) static displacement and strain measurements taken under proof-load level, and; (2) multi-reference impact test (MRIT) data from one of the spans of a three span, cast-in-place reinforced concrete (RC) T-beam Bridge. MRIT was used to generate the modal data for computation of modal flexibility and displacement profiles. The St-Id procedure used during this application was designed to mitigate epistemic uncertainty in the data interpretation process. Successful results from MRIT demonstrated the reliability of applications for bridge condition assessment based on impact testing.

Abstract: When detecting the large objects by infrared thermal method, it is difficult to get a whole panoramic picture. So it needs to stitch some infrared thermography. Image mosaic includes 4 steps, feature detection, feature registration, image transformation and image fusion. This paper studies about an infrared thermograph mosaic algorithm based on the feature point detection and registration, and realizes it in MATLAB.

Abstract: The starting time of Dragonite hydropower station in Dadu River Sichuan delayed, which led to the depth of the cofferdam cut-off wall reduced in actual construction. In order to adapt to this situation, it’s necessary to optimize the processing scheme of sand layer dam foundation which is put forward in the feasibility study stage. Combined with the characteristics of engineering, considering to reduce or cancel the curtain grouting in coarse grain granite foundation of riverbed on the right bank in the feasibility stage design, this paper is aimed to study on the optimization design of Dragonite hydropower station dam foundation. The paper has not only a great guiding significance in engineering construction process, but also gives references to the similar earth-rock dam project for treatment of sand layer dam foundation and the arrangement of dam foundation seepage control system.

Abstract: Through the field test data comprehensive analysis, the construction parameters of dynamic compaction can be obtained.The comparison of the before and after dynamic compaction reinforcement effect shows that the collapsible loess foundation after the dynamic compaction treatment, the soil dry density increases by approximately 10%, void ratio reduces by about 15%,bearing capacity increases by 15% or more and collapsible disappears. According to the construction practice of large-scale dynamic compaction method in the south line of Jinan around the city expressway, discusses the key problems should be noted during the construction process and treatment methods of special sections, quality testing methods and evaluation standards.

Abstract: Discussed the principle and the installation of the fiber bragg grating sensor of the displacement and the temperature. Combined with the wireless network technology to construct the monitoring system of the rail bridge bearing, which run long-term continuously and online to monitor the displacement, the temperature and the relations between them. Analysed the mass historical monitoring data from the system in detail and gained the result. This paper revealed the physical significance of the monitoring data, provided the basis for the maintenance.

Abstract: Conventional triaxial compression tests of coal specimens are carried out by MTS815 servo-controlled rock mechanical test system, and the strength and deformation characteristics of coal under different confining pressure are analyzed. On that basis, bolt supporting mechanism of surrounding rocks of roadways driving along next goaf is studied.

Abstract: In order to understand the influence on stress of surrounding rock and lining structure in metro tunnel after the loess is soaking, based on the Xi'an Metro Line 2, with the help of numerical simulation program, choosing tow working condition: before soaking and after soaking to carry out comparative trial, combined with the field monitoring data, we put forward that: After soaking the surrounding rock around tunnel top and bottom have some tendency to squeeze in , while the left and right side have tendency to run away, as far away from the tunnel ,the internal displacement of surrounding rock educes gradually; Inside the soaking zone, the maximum principal stress of surrounding rock after soaking is bigger than before, while outside the zone, it's contrary; After soaking the maximum bending moment and axial force of lining increases 7% and 15% respectively, and the rockbolts bear compressive force, they lost the supporting effect almost. In a word, if heavy rain floods into loess surrounding rock suddenly, in short time the metro tunnel is safe and stable, while for a long run, not timely waterproof and drainage will bring to the metro operation potential risk.