Research on Underground Pipeline Detection Method Based on Background Matrix Subtraction and Three-Dimensional Velocity Spectrum
Haowei Ji,
Jian Peng,
Minglei Ma,
Jie Ge
Issue:
Volume 11, Issue 2, March 2023
Pages:
14-25
Received:
17 March 2023
Accepted:
6 April 2023
Published:
13 April 2023
Abstract: Ground-penetrating radar (GPR) can detect urban underground pipelines and image their spatial distribution. However, due to the interference of direct wave and ground reflected wave in radar profile, the detection accuracy of underground pipeline depth is low. In order to improve the reliability and accuracy of the interpretation of ground penetrating radar data, it is necessary to suppress the noise, and then to detect underground pipelines. Firstly, on the basis of data collection, a background matrix subtraction (BMS) method is proposed to suppress noise signals, and the Noise reduction effect is compared and analyzed by two groups of simulation data and two groups of measured data examples with the method of reducing average channel and singular decomposition. Then, a three-dimensional velocity spectrum (3DVS) method is proposed to estimate the buried depth of underground pipeline in radar profile, and the propagation velocity of electromagnetic wave in underground media is calculated by automatically scanning the hyperbolic reflection signal. The estimated velocity is used to carry out back-propagation migration (BPM) processing on the ground penetrating radar profile, and the underground pipeline is accurately detected. Finally, the underground pipeline detection method based on BMS and 3DVS is applied to a residential area in Nanjing, Jiangsu, China. The detection results show that the effect of BMS is obviously better than that of mean-reducing method and singular decomposition method, which can suppress the noise well on the basis of ensuring that the effective signal is not lost. It is helpful to identify the characteristics of target signal in ground penetrating radar profile, and improve the accuracy and reliability of data interpretation. The error between the velocity value estimated by the 3DVS method and the real value is less than 3.8%, and the buried depth error of pipeline target in the obtained data is 1.4%, which indicates that the algorithm has practical application value and can realize the accurate positioning of underground pipelines.
Abstract: Ground-penetrating radar (GPR) can detect urban underground pipelines and image their spatial distribution. However, due to the interference of direct wave and ground reflected wave in radar profile, the detection accuracy of underground pipeline depth is low. In order to improve the reliability and accuracy of the interpretation of ground penetrat...
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Study on Mixing Equipment Parameters of Cement Stabilized Macadam
Zhibin Wang,
Xiaosen Wang,
Wenli Qiu,
Yan Luo,
Zhongyin Xu
Issue:
Volume 11, Issue 2, March 2023
Pages:
26-29
Received:
25 May 2023
Accepted:
13 June 2023
Published:
27 June 2023
Abstract: The mixing uniformity of cement stabilized crushed stone includes two aspects, one is the uniformity of cement coating on aggregate, and the other is the uniformity of coarse and fine aggregate distribution. The uneven cement coating aggregate results in the segregation of base strength distribution. The uneven distribution of coarse and fine aggregates leads to the density segregation of the base layer. Optimization of mixing intensity and mixing time can effectively improve mixing uniformity. The strengthening mechanism of vibration mixing and double mixing tank mixing on cement stabilized gravel mixing was compared and analyzed. Relying on the construction site 800 stable gravel mixing equipment, the key technical parameters affecting the mixing effect were analyzed. The results showed that increasing the number of mixing tanks can effectively solve the problem of short mixing time of continuous mixing equipment. The mixing quality could be improved effectively by increasing the effective mixing time to more than 35s with double mixing tanks; Vibration mixing and forced mixing form energy complementary to solve the inefficient zone of mixing. When vibration mixing is adopted, the vibration frequency should be controlled above 35Hz, increasing the mixing intensity can improve the mixing effect; the selection of filling rate should consider mixture quality and production efficiency. The filling rate of mixing tank is controlled at about 70%, which can ensure the uniform binding of cement binder on aggregate surface.
Abstract: The mixing uniformity of cement stabilized crushed stone includes two aspects, one is the uniformity of cement coating on aggregate, and the other is the uniformity of coarse and fine aggregate distribution. The uneven cement coating aggregate results in the segregation of base strength distribution. The uneven distribution of coarse and fine aggre...
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