Evaluation of Electrical Resistivity for Non-destructive Seepage Detection on an Urban Underground Diaphragm Wall

2020 ◽  
Vol 25 (1) ◽  
pp. 1-14
Author(s):  
Cai Yang ◽  
Shengdong Liu ◽  
Enjie Ding ◽  
Haiping Yang ◽  
Jingyan Xie
Keyword(s):  
Electrical Resistivity ◽  
Apparent Resistivity ◽  
Diaphragm Wall ◽  
Coupled Analysis ◽  
Leakage Detection ◽  
Response Characteristics ◽  
Before And After ◽  
Potential Methods ◽  
Self Potential ◽  
Non Destructive

With the continuous development of urban underground space, non-destructive methods for diaphragm wall leakage detection are becoming increasingly important. Recent studies have shown that the apparent resistivity, stimulated current, and self-potential can be used as indicator parameters for non-destructive diaphragm wall leak detection. The diaphragm wall seepage evaluation of a subway station was carried out using the above indicator parameters. The response characteristics of apparent resistivity, stimulated current, and self-potential were obtained before and after excavating the diaphragm wall. The results obtained by this study reveal that an area is very likely to be a seepage area when there are significant differences amongst the three measurement parameters. The self-potential is greatly affected by field interference; the stimulated current is a direct sign of seepage, and indicates that seepage occurs when the stimulated current increases; the apparent resistivity macroscopically indicates rupture or seepage in the diaphragm wall. The field experiment verified the feasibility of detecting diaphragm wall seepage using coupled analysis based on electrical resistivity and self-potential methods.

scholarly journals Assessment of Timber Roof Structures before and after Earthquakes

Buildings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 528
Author(s):  
Nikola Perković ◽  
Mislav Stepinac ◽  
Vlatka Rajčić ◽  
Jure Barbalić
Keyword(s):  
Test Methods ◽  
Timber Structures ◽  
Destructive Testing ◽  
Policy Makers ◽  
Load Bearing ◽  
Existing Structures ◽  
Roof Structure ◽  
Before And After ◽  
Timber Roof Structures ◽  
Non Destructive

The global objective of sustainable development has been greatly directed toward the preservation of existing structures. Therefore, condition assessment and reconstruction of existing timber structures have been gaining importance in recent times. This is particularly evident on timber roofs whose elements are exposed to degradation, either because of rheological effects or due to the direct influence of moisture and biological factors. In case of accidental events, such as an earthquake, the question of the structure’s condition is essential for the condition of the entire building. In order to prove the load-bearing capacity and serviceability of existing structures, as well as to check the need for reconstruction, it is necessary to define crucial parameters that are influencing the condition of materials, elements, and systems. Although there are many non destructive testing methods, the frequency and scope of their use, as well as the decision-making approach, have not been defined. In the paper, non-destructive and semi-destructive methods frequently used for timber structures are explained. A systematic review of criteria to be used in the assessment of load-bearing timber structures in a seismic active area was the main objective of this paper as well as the illustration of non-destructive and semi-destructive test methods through a case study involving roof construction of a hundred-year-old building in Zagreb, Croatia. Pre- and post-earthquake inspection was made. The overall condition of the roof structure after two significant earthquakes can be assessed as satisfactory given that the observed system is a large-span and massive roof structure. The presented results and identification of typical damages after the earthquake are presented in order to facilitate policy makers and for the future implementation of development strategies in the renovation of the city.

scholarly journals Study of the Behavior of Structural Materials Treated with Bioconsolidant

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5369
Author(s):  
Yolanda Spairani ◽  
Arianna Cisternino ◽  
Dora Foti ◽  
Michela Lerna ◽  
Salvador Ivorra
Keyword(s):  
Structural Materials ◽  
Mechanical Tests ◽  
Existing Building ◽  
Experimental Campaign ◽  
Stone Materials ◽  
Before And After ◽  
Optical Photomicrograph ◽  
Stone Material ◽  
Artificial Stone ◽  
Non Destructive

In this article, the effectiveness of the bioconsolidation technique applied to degraded structural materials is illustrated as a new method of consolidation and conservation of the existing building heritage in a less invasive way. Satisfactory results have been obtained by an experimental campaign carried out through non-destructive diagnostic tests, static destructive mechanical tests, and microstructural analyses on a series of natural stone material specimens and artificial stone materials before and after the use of bioconsolidants. The consolidated specimens have been tested after three to four weeks after the application of the M3P nutritional solution on each specimen. The effect on the microstructure of this technique has also been observed using scanning electron microscope and optical photomicrograph, the formation of new calcium carbonate crystals promoting the structural consolidation of the materials under examination was observed in all the specimens analyzed.

scholarly journals Influence of the surface finishing on ultrasound velocity in wood

2008 ◽  
Vol 56 (2) ◽  
pp. 211-216
Author(s):  
Tomáš Špaček ◽  
Mária Kotlínová ◽  
Michal Kloiber ◽  
Josef Polášek
Keyword(s):  
Ultrasound Velocity ◽  
Diagnostic Methods ◽  
Surface Finishing ◽  
Detector Surface ◽  
Before And After ◽  
Non Destructive ◽  
Ultrasound Testing

Non-destructive diagnostic methods are very useful for monumental buildings. This paper deals with one of these technique, namely with ultrasound testing and influence of surface finishing on ultrasound velocity measured by means of device the Arborsonic Decay Detector. Surface finishing (Primalex – thick synthetic film of the surface finishing, Luxol – Extra – thin synthetic film of the surface finishing and Impranal Profi SL – thick acryl film the surface finishing) were selected and tested in this research. The transmittion time was measured and velocity was converted from it. This was compared before and after application of surface finishing.

Academic Writing Teaching Method for Arab Students: A Case Study in a Health Sciences University in the U.A.E

2021 ◽  
Vol 2 (3) ◽  
pp. 8-19
Author(s):  
Omnia Ibrahim
Keyword(s):  
United Arab Emirates ◽  
Academic Writing ◽  
Teaching Method ◽  
Health Sciences ◽  
Sentence Structure ◽  
Writing Course ◽  
Before And After ◽  
Arab Students ◽  
Potential Methods ◽  
English Academic Writing

This study examines the difficulties faced by Arab students in the tertiary level in creating a well-written paragraph in English academic writing. The participants were approximately 40 students from RAK Medical and Health Sciences University located in Ras Al Khaimah in The United Arab Emirates. The study’s significance is to propose potential methods and solutions for academic English instructors to improve the students’ performance by designing a writing course based on the pre-and post-tests that were used to monitor students’ progress in writing before and after the course of Academic writing. Pre-tests were conducted to analyze the needs of the students. The analyses revealed that the participants had trouble using the writing fundamentals like grammar, vocabulary, and sentence structure. After implementing the course topics, the results of the post-tests showed changes in the students’ academic writing performance. The study concludes that to obtain the best results from the courses of English Academic writing, the course should be based on the difficulties faced by the students. It also shows that before applying any academic writing course, the instructor has to carry out an error or needs analyses to identify the weak points of the group, then the course can be designed accordingly.

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