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Deterioration evaluation of tunnel structures is the prerequisite for the tunnel's daily traffic safety management, maintenance planning, and service life prediction. Previous studies primarily rely on material degradation tests and theoretical analysis, often lacking the support of long‐term field monitoring data. This study aims to address this gap by implementing a structural health monitoring system including 48 strain gauges installed in an underwater shield tunnel in 2013. More than 8 years of data were obtained, and an irreversible strain‐based evaluation framework was proposed. This framework operates in two steps: first, it separates the irreversible strain and its damage‐induced part from the total strain. Second, it assesses the segments' damage status using the hypothesis test method. Results show that the mean irreversible strain of 41 monitoring points is 43 με over 8 years, agreeing well with the predictions based on the concrete shrinkage and creep theory. It is also found that the irreversible strain and elastic strain at different monitoring points vary significantly but they are highly correlated. Quantitative results from the hypothesis test show that the irreversible strain is induced mainly by the concrete shrinkage and creep, rather than segment damage. This study provides a method for early‐stage performance diagnosis of the tunnel segment during its service life. [ABSTRACT FROM AUTHOR]

Objective To establish multiplex system of 16 miniSTR loci, and explore its application value for the degraded materials in forensic medicine. Methods The multiplex system of 16 miniSTR loci was established using a six-dye fluorescence labeling technology and its application value in forensic medicine was assessed. Results A six-dye fluorescence labeling miniSTR amplification kit was developed, which enabled 15 autosomal STR loci, Amelogenin locus and DYS391 to be typed simultaneously. This method showed good specificity and could provide stable and accurate typing results with a sensitivity of 50 pg. This system also provided a good test result for the normal biological sample of actual cases. Conclusion The multiplex system of 16 miniSTR loci has application value for degraded and trace materials with the advantages of high sensitivity and database compatibility, which can be used for forensic casework.

Monitoring roof stress is essential for identifying structural anomalies and preventing disasters during underground construction. However, current sensors mainly focus on monitoring in one dimension, and it is challenging to obtain the mechanical status of the overall roof owing to the limitations of sensor numbers and the working environment. Therefore, we aimed to present an overall sensing method for the three-dimensional stress status of a roadway roof through machine learning (ML) based on limited monitoring points. First, the framework of the overall sensing method was developed, where a three-dimensional stress sensor was created to obtain the mechanical behaviours of some sensitive positions, and an ML model driven by the physical mechanism and limited monitoring data was developed to derive the overall stress situation. The developed sensor was installed in a case study, and the ML model was formulated based on the field-monitoring data. A series of experiments were conducted to derive the stress distribution of the roadway roof in the study case. Furthermore, a numerical simulation was conducted to compare the reasonability of the deduction results. The experimental results indicated that the deduction results of roof stress were reasonable, and thus the proposed sensing method is reliable. [ABSTRACT FROM AUTHOR]

As a widely used reinforcement method in tunnel engineering, the accuracy of models in numerical analysis has a vital influence on the reliability of the analysis results. To solve the problem of hard modeling for complicated models, this paper proposes to build models of different characteristics automatically by the means of Enterprise Knowledge Language (EKL) of CATIA, combining knowledge engineering template with parameterization. Furthermore, the stability of surrounding rocks and the distribution features of plastic areas were studied in different cases by CATIA-ABAQUS model. Besides, the effects and contributions of several parameters, including the rock-bolt diameter and interval between rock-bolts have been studied. It was found that: (1) Rock-bolt has a notable effect on the stability of the surrounding rocks. Increasing the diameter of rock-bolts contributes to significantly reduce the plastic area and the vertical displacement. With the increase of the quantity and the diameter of anchors, the degree of influence gradually weakens, showing the logarithmic relationship; (2) When the quantity and diameter of rock-bolts are constant, in the case in which the intervals between rock-bolts are various, the plastic area of surrounding rocks and the axial stress of rock-bolts are larger than that of the same distance, while the vertical displacement are uniform. (3) The excavation process has a great influence on the axial stress of rock-bolts and the redistribution of stresses in the surrounding rock.

The opening of segment joints is vital to structural stability and leakage prevention for the underwater shield tunnels and it is governed by many environmental variables, e.g., water pressure, earth pressure, and temperature. Identifying the key variables and selecting a reliable predictive model for the joint opening are challenging but important tasks but they are usually done according to subjective judgments. To develop a reliable predictive model, the Nanjing Yangtze River tunnel was introduced as a case study for field monitoring and theoretical analysis. First, the structural health monitoring system in this shield tunnel was used to construct a database of measurements including joint opening, water pressure, earth pressure, and temperatures in the escape layer and inside the segment. Then, Bayesian model class selection was conducted for the variable selection and model construction. Consequently, the water pressure and temperature inside the segment were identified as the input variables for joint opening evaluation. This two-parameter model was validated by using the measurement data. It is useful for the evaluation of similar projects in tunneling engineering. [ABSTRACT FROM AUTHOR]