[4] [1] [5] At about 19:00 on the evening of February 7, 2018, the tail of the shield machine at 1.35 km from the right line of Ludao Lake to Huchong suddenly permeated, and the workers tried to plug the leak unsuccessfully.

At around 20:40, the permeable area of the site expanded, resulting in the deformation and damage of the tunnel segments, causing the collapse of more than 30 meters of West Jihua Road on the ground, resulting in 11 deaths, 1 missing, 8 injuries, and a direct economic loss of about 53.238 million yuan.

The investigation team determined that the immediate cause of the accident was as follows: "First, there is a deep water-rich silt layer in the accident section and is close to a strong permeable medium and coarse sand layer, the groundwater is confined, and the risk of permeable sand and mud collapse is high when the shield machine passes through the section; Second, the sealing performance of the shield tail sealing device decreases during use, and the shield tail seal is broken down by external water and soil pressure, resulting in a permeable sand gushing channel; Third, under the serious condition of mud and sand, the rescue operation was continued in the tunnel, and the evacuation was not timely; Fourth, after the tunnel structure is damaged, a large amount of sediment quickly pours into the tunnel, forming a strong sediment flow and air waves in the narrow space to impact the direction of the tunnel entrance, resulting in the failure of some personnel to escape, resulting in serious consequences of casualties."

Among them, 1 person who died in the accident was exempted from accountability, 2 enterprise personnel have been investigated by the public security organs and compulsory measures have been taken, 1 person has been handled in a separate case, and the rest of the enterprise and government officials have been recommended to be given corresponding party discipline and government sanctions and accountability.

[7] In the early morning of June 16, 2019, water leakage occurred in the tunnel during the freezing operation of the connecting channel in the Hulu section, and no casualties were caused at the scene.