1 Analysis of common diseases of subway tunnel lining concrete structure: 1. 1 Corrosion diseases of subway tunnel lining concrete. In the application of subway tunnel lining concrete structure engineering, one of the common diseases is concrete corrosion. The appearance of concrete corrosion disease seriously affects the structural safety of subway tunnel lining concrete, and the corrosion phenomenon of its engineering structure also has a great impact on the service life of engineering structure and subway traffic safety. In addition, from the analysis of the causes of concrete structure corrosion diseases, it is mainly caused by the corrosion of subway tunnel lining concrete structure. The reasons are divided into chemical corrosion, biological corrosion and physical corrosion. Among them, chemical corrosion accounts for a large proportion in subway disease cases, with great harm and high maintenance cost. 1.2 deformation disease of subway tunnel lining concrete structure In the application of subway tunnel lining concrete structure engineering, with the increase of service time and the change of structural static load force, tunnel lining concrete structure appears deformation disease, which is also a common structural disease phenomenon. Among them, the occurrence of structural deformation diseases is mainly manifested as: the compressive strength of the structure is reduced, and the internal stress of the structure is unbalanced under the relatively stable static load, resulting in structural extrusion deformation. The early damage caused by structural deformation disease is small, which can be repaired by certain supporting and strengthening technology. Later, with the deterioration of deformation diseases, it is easy to cause other safety accidents such as structural collapse.
1.3 settlement disease of subway tunnel lining concrete structure. In the construction application of subway tunnel lining concrete structure, poor foundation settlement disease is a common disease phenomenon. From the point of view of structural balance, structural settlement diseases are mainly manifested as follows: the concrete structure of subway tunnel lining settles, which leads to the unbalanced stress of subway foundation, structural frame and tunnel structure, and then some structural cracks appear. Secondly, the occurrence of settlement disease of subway tunnel lining concrete structure has caused great harm to the foundation safety and stability of surface buildings and the structural safety of surface buildings. 1.4 carbonation of subway tunnel lining concrete. Judging from the application environment of subway tunnel lining concrete structure, carbonation disease is also common in its structure. Among them, it is analyzed that there are carbonation diseases in the lining concrete structure of subway tunnel, which are mainly manifested as: the performance of lining concrete structure is invalid and the structure is peeled off, which has caused serious harm to the control of supporting force between structures and structural safety. In addition, the appearance of carbonation disease of lining concrete structure has caused great harm to the design life guarantee of subway tunnel engineering, as well as the traffic safety and structural safety of subway.
1.5 Cracks and leakage of concrete lining of subway tunnel. In the application of subway tunnel lining concrete structure, structural cracks and structural leakage are common diseases. Among them, the appearance of structural cracks and leakage leads to the decrease of relative strength and structural safety of tunnel engineering, which has caused great harm to the safe and stable use of the project. In addition, from the analysis of the application of power safety in subway operation, the appearance of structural cracks and leakage has caused great harm to the safe and stable operation of related power facilities, which is not conducive to the safe and stable operation of subway projects.
2. Analysis of common technologies for detection and test of subway tunnel lining concrete 2. 1 sampling detection technology. Through the analysis of the detection status of subway tunnel lining concrete structure, sampling detection technology is a commonly used detection technology of lining concrete structure. When implementing sampling inspection technology, structural safety, inspection efficiency and inspection cost are considered. Usually, in the detection operation, the test block simulating the application environment of subway tunnel lining concrete is prepared, and the compressive strength and static load of the test block are detected by alternating experiments in dry and wet environments and adding corrosive chemical composition solutions. Then, based on the test data, combined with the design data and safety requirements, the quality of subway tunnel lining concrete structure is evaluated, so as to improve the construction quality reasonably and ensure the practical application effect of the project. 2.2 Ultrasonic testing technology. The application of ultrasonic testing technology in subway tunnel lining concrete structure detection is a commonly used nondestructive testing technology. In practical application, this technology mainly detects the concrete structure of subway tunnel lining by erecting ultrasonic transmitter, signal receiver, antenna device and building data processing system. Combined with the data received by the system and the curve drawn by the software, the quality of the lining concrete structure of subway tunnel is analyzed in the inspection operation, and finally the purpose of reasonably evaluating the quality of the lining concrete structure, optimizing the structure maintenance technology, prolonging the service life of the structure and ensuring the safety of the subway tunnel is achieved.
2.3 rebound detection technology. In the implementation of rebound detection technology, the strength of engineering structure is calculated and evaluated according to the rebound distance and rebound value of heavy hammer and the way of spring-driven heavy hammer hitting concrete surface. In concrete operation, the structural quality of lining concrete structural surface is evaluated and tested by implementing large-area rebound measurement operation. Its technology has the advantages of simple process and accurate measurement data in practical application, but it is also limited by the detection area of equipment and devices in the operation of the unit, so its application efficiency is low in practical application. 2.4 Ultrasonic-rebound synthesis method. In the construction of subway tunnel lining concrete structure, due to the complexity of structural design, the application of single technology can not comprehensively and effectively evaluate the application quality of structural construction. Therefore, it is also a common detection technology to test the lining concrete structure by using ultrasonic rebound synthesis method. The application of ultrasonic-rebound comprehensive method is an experimental work that combines ultrasonic detection technology and rebound detection technology to detect the quality of subway tunnel lining concrete. Through the analysis of the comprehensive test data in the actual test, the effect of reasonably evaluating the present situation of regional structure quality is achieved.
Conclusion According to the present situation of subway tunnel lining concrete and the types of diseases of lining concrete structure, the construction unit mainly uses ultrasonic detection technology and rebound detection technology to detect and evaluate the structure quality. In addition, for projects with complex structure, many processes and high detection requirements, ultrasonic rebound synthesis method is usually used to detect the structural quality. Secondly, in the selection of specific detection technology, the detection unit should select relevant detection and test technology according to the disease characteristics of the engineering structure to ensure the qualification and effectiveness of the implementation quality of the detection operation.
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