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24 pages, 13387 KiB

Open AccessArticle

Research on a Measurement Method for Downhole Drill String Eccentricity Based on a Multi-Sensor Layout

by Hongqiang Li and Ruihe Wang

Sensors 2021, 21(4), 1258; https://doi.org/10.3390/s21041258 - 10 Feb 2021

Cited by 2 | Viewed by 5493

Abstract

The drill string used in drilling is in a complex motion state downhole for several kilometers. The operating attitude and eccentricity of the downhole drill string play important roles in avoiding downhole risks and correcting the output of the imaging measurement sensor while [...] Read more.

The drill string used in drilling is in a complex motion state downhole for several kilometers. The operating attitude and eccentricity of the downhole drill string play important roles in avoiding downhole risks and correcting the output of the imaging measurement sensor while drilling (IMWD). This paper proposes a method for measuring eccentricity while drilling using two sets of caliper sensors coupled with a fiber-optic gyroscope for continuous attitude measurement, which is used to solve the problem of the quantitative measurement of complex eccentricity that changes in real-time downhole. According to the measurement and calculation methods involved in this article, we performed simulations of the attitude of the drill string near where the IMWD tool is located in the wellbore under a variety of complex downhole conditions, such as centering, eccentricity, tilt, buckling, rotation, revolution, etc. The simulation and field test results prove that the distance between the imaging while drilling sensor and the borehole wall is greatly affected by the downhole attitude and revolution. The multi-sensor layout measurement scheme and the data processing based on the above-mentioned measurement involved can push the drill collar movement and eccentricity matrix specifically studied downhole from only qualitative estimation to real-time measurement and quantitative calculation. The above measurement and data processing methods can accurately measure and identify the local operating posture of the drill string where the IMWD sensor is located, and quantitatively give the eccentric distance matrix from the measuring point to the borehole wall required for environmental correction of the IMWD sensor. Full article

(This article belongs to the Special Issue Advanced Fiber-Optic Sensors in Civil Engineering)

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15 pages, 6392 KiB

Open AccessArticle

A Fiber Bragg Grating Borehole Deformation Sensor for Stress Measurement in Coal Mine Rock

by Wusheng Zhao, Kun Zhong and Weizhong Chen

Sensors 2020, 20(11), 3267; https://doi.org/10.3390/s20113267 - 8 Jun 2020

Cited by 17 | Viewed by 3153

Abstract

A borehole deformation sensor for long-term stress monitoring in coal mine rock based on optical fiber Bragg gratings (FBGs) is presented. The sensor converts borehole deformation into optical fiber strain by using four rings. For each ring, two FBGs are bonded with the [...] Read more.

A borehole deformation sensor for long-term stress monitoring in coal mine rock based on optical fiber Bragg gratings (FBGs) is presented. The sensor converts borehole deformation into optical fiber strain by using four rings. For each ring, two FBGs are bonded with the ring to measure the borehole deformation, and a reference FBG free from mechanical load is introduced to remove the temperature effect. Two simple checks on the test data can be performed to improve the test accuracy. Laboratory and field tests were conducted to validate the accuracy and long-term performance of the sensor. The results show that the sensor is capable of measuring stress in rock with good accuracy, and it performs well over a long period of time in coal mines. The developed sensor provides an approach for the long-term monitoring of stress changes in coal mine rock. Full article

(This article belongs to the Special Issue Advanced Fiber-Optic Sensors in Civil Engineering)

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13 pages, 3376 KiB

Open AccessFeature PaperArticle

Strain Conditions Monitoring on Corroded Prestressed Steel Strands in Beams Based on Fiber Bragg Grating Sensors

by Guo-Xi Fan, Fan-Tong Lin, Peng Li, Ji-Gang Han, Huai-Shuai Shang, Ye Wang and Han Zheng

Sensors 2020, 20(8), 2288; https://doi.org/10.3390/s20082288 - 17 Apr 2020

Cited by 5 | Viewed by 2730

Abstract

Fiber Bragg Grating (FBG) sensors, with excellent properties, have been widely adopted to monitor the mechanical parameters in civil engineering in recent years. On the other hand, the current study on fatigue performance of corroded prestressed steel strands is still limited, and this [...] Read more.

Fiber Bragg Grating (FBG) sensors, with excellent properties, have been widely adopted to monitor the mechanical parameters in civil engineering in recent years. On the other hand, the current study on fatigue performance of corroded prestressed steel strands is still limited, and this is mainly because the long-term strain conditions monitoring is difficult to conduct. Based on the aforementioned considerations, a total of six beam specimens were fabricated in this study. The loading mode of four points bending was adopted in the form of sinusoidal waves in the experiments. On basis of the experimental results, it can be concluded that the fatigue life of the beam decreases sharply with the increase of the corrosion rate of steel strands. Besides, with the increase of the maximum fatigue load, the fatigue life of the beam will decrease significantly. Furthermore, the existing fatigue damage of steel strand inside the beam before corrosion may further accelerate its fatigue failure. As a result, the fatigue life of the beam is reduced because of the stress concentration. Under the same external load, the strain increment and the residual strain of steel strands in the stages of loading and unloading after corrosion increase significantly compared with other stages, while the existing residual strain always shows an increasing trend at various static loading stages. Therefore, the corrosion of steel strand seriously affects not only its mechanical properties, but also its fatigue performance. Finally, the FBG sensors are capable of measuring the steel strand strain, as well as the long-term strain conditions. Full article

(This article belongs to the Special Issue Advanced Fiber-Optic Sensors in Civil Engineering)

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18 pages, 9689 KiB

Open AccessArticle

On a Sensor Placement Methodology for Monitoring the Vibrations of Horizontally Excited Ground

by Aneta Herbut, Jarosław Rybak and Włodzimierz Brząkała

Sensors 2020, 20(7), 1938; https://doi.org/10.3390/s20071938 - 30 Mar 2020

Cited by 18 | Viewed by 2763

Abstract

In this paper, the problem of optimal sensor arrangement during vibration monitoring is analysed. The wave propagation caused by horizontal excitation is investigated to predict the areas of the largest ground and structure response. The equations of motion for a transversally isotropic elastic [...] Read more.

In this paper, the problem of optimal sensor arrangement during vibration monitoring is analysed. The wave propagation caused by horizontal excitation is investigated to predict the areas of the largest ground and structure response. The equations of motion for a transversally isotropic elastic medium with appropriate absorbing boundary conditions are solved using the finite element method (FlexPDE software). The possibility of an amplified soil medium response is examined for points located on the ground surface and at various depths. The results are presented in the form of a dimensionless vibration reduction factor, defined as the ratio of the peak particle velocity observed at the selected depth to the corresponding value observed at the ground surface. Significant amplifications (≈50%) can be observed below the ground surface, especially in the case of a weak layer below a stiff layer. The effect of vibration amplification is most significant near the boundary surface of two layers. For the points located on the ground surface, the greatest peak particle velocities are observed in the direction perpendicular to the load direction. However, the greatest vertical velocity component at the ground surface is observed in front of the applied force. Full article

(This article belongs to the Special Issue Advanced Fiber-Optic Sensors in Civil Engineering)

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15 pages, 6480 KiB

Open AccessArticle

Laboratory and In-Situ Testing of Integrated FBG Sensors for SHM for Concrete and Timber Structures

by Kristýna Čápová, Lukáš Velebil and Jan Včelák

Sensors 2020, 20(6), 1661; https://doi.org/10.3390/s20061661 - 17 Mar 2020

Cited by 16 | Viewed by 3526

Abstract

Long-term structural health monitoring (SHM) plays an important role in the safety of public transport infrastructure such as bridges or tunnels and warns in the event of any emerging problem. This article describes development and testing of system based on fiber Bragg grating [...] Read more.

Long-term structural health monitoring (SHM) plays an important role in the safety of public transport infrastructure such as bridges or tunnels and warns in the event of any emerging problem. This article describes development and testing of system based on fiber Bragg grating (FBG) sensors that can detect changes in strain and temperature. The first phase of the research has been focused on the development of new fiber optic sensors for the monitoring of concrete structures and their investigation in laboratory conditions. The work also shows novel applicability of the same FBG technology for glulam structures. Mechanical loading tests of the concrete beam as well as glulam beam with embedded sensors were carried out. Data measured by developed fiber optic sensors were compared with the readings from reference sensors as well as with the analytically calculated values. The achieved results proved good agreement between the measured data, analytical data and reference methods. In second phase of the research, the pilot installation of the sensors was carried out on the newly constructed prestressed-concrete bridge. The bridge was monitored throughout pre-stressing phase and monitoring continued after the completion of the construction works. Problems with the fragility of the sensors occurred during the measurements, but the obtained results provide a good basis for further improvement of the system. Full article

(This article belongs to the Special Issue Advanced Fiber-Optic Sensors in Civil Engineering)

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14 pages, 4320 KiB

Open AccessArticle

A Plastic Optical Fiber Sensing System for Bridge Deflection Measurement

by Dong Yang, Jin-Qi Wang, Wei-Xin Ren and Jing Zhang

Sensors 2020, 20(2), 480; https://doi.org/10.3390/s20020480 - 15 Jan 2020

Cited by 5 | Viewed by 3464

Abstract

Deflection is one of the key parameters that reflects the state of a bridge. However, deflection measurement is difficult for a bridge that is under operation. Most existing sensors and measuring techniques often do not meet the requirements for health monitoring for various [...] Read more.

Deflection is one of the key parameters that reflects the state of a bridge. However, deflection measurement is difficult for a bridge that is under operation. Most existing sensors and measuring techniques often do not meet the requirements for health monitoring for various types of bridges. Therefore, based on changes of optical fiber intensity, a novel sensing system using connected pipes to measure bridge deflection in different positions is proposed in this paper. As an absolute reference, the liquid level position along the structure is adopted for the deflection measurement, and an additional external reference to the ground is not needed in this system. The proposed system consists of three parts: connected pipes to connect the measurement points along the structure, liquid to fill in the connected pipes, and the sensing element to detect the change of level. A plastic optical fiber sensor based on the intensity change is used as the sensing element of the developed system. Then, a set of experimental tests are conducted for performance evaluation purposes. Results show that this system has an accurate linear response and high reliability under various environmental conditions. The deflection of the test beam measured by the sensor agrees with linear variable differential transformer (LVDT) within an error margin of 2.1%. The proposed system shows great potential applicability for future health monitoring of long-span bridges. Full article

(This article belongs to the Special Issue Advanced Fiber-Optic Sensors in Civil Engineering)

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17 pages, 10306 KiB

Open AccessArticle

Alternative Approaches to Measurement of Ground Vibrations Due to the Vibratory Roller: A Pilot Study

by Jan Nedoma, Martin Stolarik, Stanislav Kepak, Miroslav Pinka, Radek Martinek, Jaroslav Frnda and Michael Fridrich

Sensors 2019, 19(24), 5420; https://doi.org/10.3390/s19245420 - 9 Dec 2019

Cited by 10 | Viewed by 3461

Abstract

At present, one of the primary tasks of the construction industry is to build transport infrastructure. This concerns both the construction of new bypasses of towns and the repair of existing roads, which are damaged by congestion, especially by freight transport. Whether it [...] Read more.

At present, one of the primary tasks of the construction industry is to build transport infrastructure. This concerns both the construction of new bypasses of towns and the repair of existing roads, which are damaged by congestion, especially by freight transport. Whether it is a new building or a reconstruction, it is always very important to choose a suitable method of subsoil treatment. One of the most commonly used methods for soil treatment is currently compaction using vibratory rollers. This method is very effective both in terms of results and due to its low financial demands compared to other methods. Vibration is transmitted to the surrounding rock environment when compacting the subsoil using vibratory rollers. Although the intensity of these vibrations is not as pronounced as in other methods of subsoil treatment, such vibrations can have a significant effect, for example during compaction in urban areas or in an area with the presence of historical objects. Therefore, it is very advisable to monitor the effect of these vibrations on the environment during construction. This paper brings an original experimental comparative study of standard seismic instrumentation with a developed interferometric sensor for the field of monitoring vibrations generated during compaction of subsoil using vibrating rollers. The paper presents time and frequency domain results, as well as attenuation curves, which represent real attenuation of vibrations in a given rock environment. The results presented here show that a system operating on a different physical principle from the one used at present has the potential to replace the existing, very expensive, seismic equipment. Full article

(This article belongs to the Special Issue Advanced Fiber-Optic Sensors in Civil Engineering)

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Review

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25 pages, 5390 KiB

Open AccessReview

Recent Progress of Fiber-Optic Sensors for the Structural Health Monitoring of Civil Infrastructure

by Tiange Wu, Guowei Liu, Shenggui Fu and Fei Xing

Sensors 2020, 20(16), 4517; https://doi.org/10.3390/s20164517 - 12 Aug 2020

Cited by 113 | Viewed by 12039

Abstract

In recent years, with the development of materials science and architectural art, ensuring the safety of modern buildings is the top priority while they are developing toward higher, lighter, and more unique trends. Structural health monitoring (SHM) is currently an extremely effective and [...] Read more.

In recent years, with the development of materials science and architectural art, ensuring the safety of modern buildings is the top priority while they are developing toward higher, lighter, and more unique trends. Structural health monitoring (SHM) is currently an extremely effective and vital safeguard measure. Because of the fiber-optic sensor’s (FOS) inherent distinctive advantages (such as small size, lightweight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability), a significant number of innovative sensing systems have been exploited in the civil engineering for SHM used in projects (including buildings, bridges, tunnels, etc.). The purpose of this review article is devoted to presenting a summary of the basic principles of various fiber-optic sensors, classification and principles of FOS, typical and functional fiber-optic sensors (FOSs), and the practical application status of the FOS technology in SHM of civil infrastructure. Full article

(This article belongs to the Special Issue Advanced Fiber-Optic Sensors in Civil Engineering)

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