Abstract: Theory equations and norm equations are primary methods to calculate loose load of tunnel. They are established based on the statistic and analysis of loose load from finished tunnels in general. With the development of road tunnel construction, the two-way and large-span road tunnel with eight-lane in either way become a new shape in recent years. The eight-lane tunnel has an increase in excavation area and a decrease in excavation height relatively for the aim of curtailing the cost of construction and has a smaller ratio of height to width. For this reason, current calculation method of loose load whether or not apply to barge-span tunnel has been significant for tunnel design. In this paper, firstly, various calculation methods are summarized and applied to Longtoushan Road Tunnel with eight-lane and barge-span. And then, calculation results are analyzed and compared. Secondly, rationality of calculation methods for Longtoushan Tunnel is analyzed based on numerical calculation and measured data. Finally, the paper presents and discusses applicability of various methods, especially for the eight-lane and barge-span tunnel, based on its own background and above study course. The purpose of the article is to provide reference for the design of extra-large cross-section and barge-span road tunnel.

Key words: extra-large cross-section and large-span, road tunnel, loose load, applicability