Real Right Object Attribute of Urban Underground Space and Its Policy Evolution Trend

Focusing on the reform goal of modernization of urban underground space governance system and governance capacity, this paper studies the legal definition of underground space, and reveals the trend of the evolution of underground space policy, so as to provide ideas for policy supply at the national level. The research shows that in the past twenty years, the underground space policy can be divided into three stages: exploration, initial formation and standardization, centering on the construction of underground space engineering management system, property right management system and three-dimensional property right management system. However, The definition of underground space in existing policies mainly focuses on natural attributes, which confuses the distinction between surface and ground, underground space and underground engineering. Under the framework of the system of establishing the right to use construction land by layers in Article 345 of the Civil Code, underground space has legally got rid of the state of being attached to the surface since Roman law. As an independent object of the right to use underground construction land, underground space must be controlled by human beings, with specificity, independence and clear three-dimensional property rights boundary. The policy evolution shows the trend from natural attribute to legal attribute, from resources to asset capital, from engineering thinking to property right thinking, from plane thinking to three-dimensional thinking, from planned allocation to market allocation.