The authorities in Dalian, northeast China's Liaoning Province, halted all the subway construction projects in the city following recent cave-ins on Friday, the China News Service reports.
On the morning of Mar 10, water and mud suddenly gushed out from the top of a construction platform in a tunnel, accompanied by collapse of pebbles. One person went missing and was later found dead.
At around 6:30pm on Mar 16, another cave-in caused a deep hole ten meters in diameter on the road at a construction site, partially cutting off the traffic.
About 1:00pm the next day, the ground sunk about ten centimeters at another site.
Peng Fei, vice general manager of the company in charge of the city's subway construction, said that the rock formation underneath the ground in Dalian is generally porous and complicated in structure, which means it is more prone to fluid movement and seepage.
The authorities did not disclose when the construction will be resumed, the report notes.
Dalian started the construction of its first metro system in July, 2009. The project includes three subway lines, Lines 1, 2 and 4, the Xinhua news agency reported.
The three lines are designed to extend some 58.1 kilometers and carry 38,000 passengers every hour at the speed of 80 kilometers per hour, the Xinhua report said.
Subway Lines 1 and 2 are expected to be completed by the end of 2012. The time table for the construction of Line 4 has not yet been revealed.
