# Experimental Study on the Dynamic Response of an Immersed Tunnel Element Moored inside the Harbor
[PERSON] [11] used the theory of three-dimensional potential flow to study the nonlinear wave load in the floating process of large tunnel elements under the action of irregular waves and analyzed the influences of water depths, wave heights, and periods on the wave force and the motion. [PERSON] [12] studied the motion response of a moored tunnel element and mooring cable tension in the immersion stage under the action of long-period waves through physical model tests. The results showed that the heave and roll of a tunnel element under long-period waves were significantly affected by the wave period. When the wave period was smaller than the roll period, the average drift force had little effect on the net drift. Both waves and currents have important effects on mooring tension, and a better mooring scheme was obtained by comparing and analyzing different mooring schemes. [PERSON] [13; 14] also studied the dynamic response of a tunnel element in the stages of standby and freeboard elimination by using physical model tests. [PERSON] [15] analyzed the four kinds of anti-tyhoon schemes for a tunnel element and recommended an optimal mooring scheme for closed water. Most of the previous studies are aimed at the mooring of tunnel elements in open waters, corresponding to the immersion and standby stages, while for the mooring in semi-open waters, such as a mooring inside a harbor or a dock, corresponding to the prefabrication and temporary storage stages, there are few studies. It should be noted that the tunnel element moored in semi-open water is different from that in open water. The environmental conditions of the mooring in these two types of areas are quite different. Because of the shielding effect of the structures, the environmental conditions of a mooring inside the harbor will be weakened, which seems to be more favorable to the mooring stability. However, the moored tunnel element in the prefabrication stage experiences a continuous transformation from a no-load to a full-load with the progress of pouring, and the corresponding freeboard-to-draft ratio would change significantly, which is different from that in the immersion and standby stages. Moreover, it is necessary to face the difficulty that multiple elements may interfere with each other when they are moored simultaneously in the limited water space. In addition, the box-type immersed tunnel element is usually a long, wide, and shallow structure, different from ships. The dynamic response under the action of wind, waves, and a current environment also has its own unique characteristics. In short, it is extremely necessary and important to carry out corresponding research on the dynamic response characteristics of immersed tunnel elements inside the harbor. This study is based on the Shenzhong-link immersed tunnel project. The immersed tunnel consists of 32 elements and a final joint, and some elements are prefabricated in Longxue Harbor, which is located at the Pearl River estuary and may be affected by strong waves from the open sea. A floating pouring scheme inside the harbor is one of the alternative prefabrication methods. After the prefabrication is completed, a tunnel element outfitting is carried out in the harbor, and then it is transported to the sinking site by towing. There is demand for mooring inside a harbor for element prefabrication and storage before transportation. In this paper, model tests focused on the dynamic response of a tunnel element moored inside the harbor are carried out, and the dynamic response characteristics under three different external force modes (wind, waves, and combined wind and wave) are investigated, as well as the influences of element load conditions on the mooring stability. In addition, the interaction of simultaneous mooring inside the harbor by multiple elements is also analyzed.