Experiment and numerical study on the monitoring of super long cast-in-place pile temperature based on BOTDR technology

Gao, Lei; Cao, Yang; Liu, Han long; Zhao, Zi xin; Ye, Yong feng; Fan, Chuan jing; Zhang, Lun zhao; Tu, Wen jin

doi:10.1016/j.measurement.2021.109481

Cited by 14 publications

(4 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This value is consistent with the data of the center part of the pile bottom in figure 9. The temperature gradient along the depth direction is zero due to the relatively stable surface shallow temperature [29]. The difference between the data of the fixed-point optical cable of the pile and the data of the sensing point at the bottom of the pile can eliminate the influence of temperature change.…”

Section: Experimental Analysismentioning

confidence: 99%

Axial strain monitoring method of cast-in-place piles based on ultra-weak fiber Bragg grating

Zhi-Quan¹,

Lin²,

Ding³

et al. 2022

Meas. Sci. Technol.

View full text Add to dashboard Cite

The axial strain distribution of cast-in-place piles under the static load test is a reliable basis for analyzing the compressive bearing capacity of the pile foundation. However, it is still difficult to achieve high-precision, high-sensitivity, real-time, and distributed monitoring of the pile foundation at the same time. To improve the monitoring of the stress distributions of the pile foundation, a fixed-point ultra-weak fiber Bragg grating (UWFBG) strain-sensing optical cable is designed on the basis of the large capacity characteristic of UWFBG. The strain sensitivity of this optical cable is 1.15 pm/με within the range of 10,000 με, which meets the accuracy requirements of pile health monitoring. The effectiveness of the designed UWFBG in pile foundation monitoring is verified through a static load test of the cast-in-place pile. The results show that the measured results of UWFBG and BOTDA (Brillouin optical time-domain analysis) have good consistency, and their average error is less than 7.5%. Compared with BOTDA, the UWFBG sensing system exhibits stronger anti-interference capability and faster response. The monitoring method proposed in this paper overcomes the shortcomings of previous monitoring methods in the static load test of the pile. The measured data can be used to calculate the detailed axial strain distribution of piles and analyze the distribution of axial force and side friction resistance of the pile. It not only provides a new monitoring method for static load test of cast-in-place piles, but also has great potential in monitoring large diameter pile.

show abstract

Section: Experimental Analysismentioning

confidence: 99%

Axial strain monitoring method of cast-in-place piles based on ultra-weak fiber Bragg grating

Zhi-Quan¹,

Lin²,

Ding³

et al. 2022

Meas. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…The working principle of OFDR is shown in Figure 2. In recent years, the distributed optical fiber monitoring technologies are used for engineering monitoring [10], such as BOTDR [11,12], BOTDA [13], BOFDA [14], OFDR [15], and so on. The comparison of various distributed optical fiber sensing technologies is shown in Table 1.…”

Section: Principle Of Ofdr Technologymentioning

confidence: 99%

“…This new pile technology is suitable for solving the problems of bump at bridge head, uneven settlement, soft soil foundation reinforcement and emergency construction. In recent years, the distributed optical fiber monitoring technologies are used for engineering monitoring [10], such as BOTDR [11,12], BOTDA [13], BOFDA [14], OFDR [15], and so on. The comparison of various distributed optical fiber sensing technologies is shown in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Model Test Study on Deformation of Snowflake Shaped Steel Sheet Pile Based on OFDR

Gao

Wang

et al. 2021

Sensors

Self Cite

View full text Add to dashboard Cite

As a newly developed pile foundation, the snowflake shaped steel sheet pile is composed of three Y-shaped sections with an included angle of 120° and has a large specific surface area, which can give full play to the side friction of pile and improve the bearing capacity of single pile. At the same time, the snowflake shaped steel sheet pile has a high strength, relatively few materials, and it has good prospects with engineering applications. In order to accurately grasp the mechanical characteristics of the snowflake shaped steel sheet pile, this paper carried out the model test of snowflake shaped steel sheet pile based on OFDR (optical frequency domain reflector) distributed optical fiber sensor technology. The results show that: (1) OFDR distributed optical fiber sensing technology can effectively monitor the strain of snowflake steel sheet pile; (2) under the vertical load, the strain of snowflake steel sheet pile decreases along the length of the pile; (3) the strain of the same section of snowflake steel sheet pile is different at different positions, the strain at the junction between web and web is basically the same as the junction between web and flange, and the strain of the pile shaft on the flange edge is larger.

show abstract

“…Recent advances in strain measurement using optical fibers provide new opportunities for monitoring the performance of piles. If the pile-soil interaction (e.g., load transfer functions t-z or p-y) is of interest, then BOTDR optical fiber sensing may be sufficient when a continuous distribution of axial forces and/or bending moments needs to be established [28]. Klar et al [29] discussed the advantages of distributed strain measurement by BOTDR compared to conventional discrete measurements (e.g., strain sensors) through the theoretical analysis of the pile-soil interaction problems.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Load-Settlement Curve Based on Load Transfer at Pile-Soil Interface

Zhang

Shi³

et al. 2022

Applied Sciences

View full text Add to dashboard Cite

A field pile loading test was carried out on the Peshawar–Karachi Motorway (PKM) project in Pakistan to show the settling mechanism of bored pile foundation in pulverized soil and the force characteristics of frictional resistance at the pile-soil interface. The changes in pile lateral frictional resistance and pile settlement during the loading-unloading process of test piles were measured and analyzed, as well as the load-settlement distribution characteristics of test piles in different soil layers, the distribution of test pile internal forces, and the changes in pile-soil relative displacement. It was established that there was considerable deterioration of pile lateral frictional resistance and residual deformation of pile tip displacement throughout the test pile load-settlement process, and the association between the pile-soil interface frictional resistance and pile-soil relative displacement was addressed. The results reveal that the frictional resistance at the pile-soil interface is directly connected to the nature of the soil layer, with a positive connection between the natural density, specific gravity, compression deformation, and the plastic index under immediate load, and a negative correlation between the natural moisture content, compression coefficient, and settlement variations after unloading. The load-settlement of the pile rose in a non-linear proportion during the loading-unloading operation, with a maximum settlement value at the pile top of 8.14 mm and a residual deformation at the pile bottom of 1.94 mm. The frictional resistance of the pile perimeter was distributed non-linearly throughout the pile depth, and the frictional resistance of the pile-soil interface was severely deteriorated at an embedded depth of 15 m, with the degradation degree of the silty soil layer being significantly smaller than that of the silty clay soil. The relative pile-soil displacement was positively linked with the lateral frictional resistance of the pile under the same load, and the correlation coefficient in silty soil was much greater than that in sandy soil.

show abstract

Experiment and numerical study on the monitoring of super long cast-in-place pile temperature based on BOTDR technology

Cited by 14 publications

References 20 publications

Axial strain monitoring method of cast-in-place piles based on ultra-weak fiber Bragg grating

Axial strain monitoring method of cast-in-place piles based on ultra-weak fiber Bragg grating

Model Test Study on Deformation of Snowflake Shaped Steel Sheet Pile Based on OFDR

Analysis of Load-Settlement Curve Based on Load Transfer at Pile-Soil Interface

Contact Info

Product

Resources

About