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The environment in the 500kV cross-linked cable tunnel is bad, which is not conducive to ensuring the joint manufacturing process, and it is easy to cause joint installation defects. A joint installation environmental control system stabilizing the temperature and humidity of the joint installation area and reducing dust particles in the air was designed and developed. A closed space in the joint area was formed by use of sliced inflatable membranes. The integration of refrigeration and air-conditioning technology, air dehumidification technology, air filtration technology and air volume adjustment technology realized temperature, humidity, and cleanliness control of the joint installation area. Stable temperature and humidity, as well as clean air atmosphere can greatly improve the installation quality of high-voltage cable joints in the complex cable tunnel environment, and help reduce the failure rate of joints.

According to the reliability theory, the size effect has a great impact on the design value on shear strength of metal-plate connector. But little research has been done. So, based on GB/T50329-2002 of China, firstly, determining the size of metal-plate at different conditions, size effect tests were then conducted on metal-plate connectors composed of a type of Chinese metal-plate and 2# SPF dimension lumber from North America. A total of 125 metal-plate connectors are tested at five angles (90°, 60°T, 120°C, 150°C, 30°T), with Five kinds of widths (50mm，85mm，125mm，150mm，180mm) for each angle. Based on the testing data, fitting curve of size effect is presented, and width-effect parameters are estimated with SPSS(Statistic Package for Social Science). Results indicate that the width effect is significant; shear strength increases with the increase of width, and stays stable after a certain width.