An earthquake relief official in Guangyuan said the city north of the provincial capital Chengdu was particularly hard hit, with about 71,300 homes being destroyed and more than 200,000 in danger of collapsing.
The death toll from the initial earthquake on May 12 has exceeded 62,500 and aid is still being delivered to the disaster zone.
On Monday, 1,800 soldiers marched to Sichuan province's Beichuan county to try and unblock a new lake formed by a landslide.
China's official Xinhua news agency reported the soldiers are carrying 10 kilograms of explosives each to blast through the debris and reduce the danger of major flooding in the future.
Thousands of people who remained there after China's worst earthquake in three decades have been evacuated in recent days as a precaution.
Conditions for millions of survivors living in makeshift camps worsened as rain fell while forecasters predicted further heavy downpours.
The government said the quake left 69 dams in danger of bursting and had created "dangerous situations" at hundreds of others.
E Jingping, the vice minister of water resources, said in Beijing that authorities had taken steps to alleviate the danger by draining and lowering the water levels at hundreds of reservoirs.
Wen Jiabao, China's prime minister, said on Saturday that the final toll could climb higher than 80,000 as he toured quake-hit Sichuan province with Ban Ki-moon, the UN secretary-general.
More than 5.4 million people have been left homeless by the quake.
The prime minister said the government needs 900,000 tents for the survivors and has urged Chinese manufacturers to make 30,000 a day.
Relief teams were working around the clock to set up temporary housing and provide food and medical care to the displaced.
A Russian military transport plane, one of 12 that are expected, carrying tents, blankets, field hospitals and other supplies landed in Chengdu, state media reported.
A French medical team has also arrived in Chengdu and had left for Guangyuan.
Although state media reported that an 80-year-old man was pulled from the rubble on Friday, rescue teams say the search for survivors is over, and the focus is now on clean-up and reconstruction operations.
Saad Attia, a member of a Dutch aid team in the town of Hanwang, told AFP: "I think we have a lot of work to do today, but it will be only finding dead bodies. I don't think there are any more survivors."
The UN secretary-general arrived from neighbouring Myanmar on Saturday and praised China's response to the earthquake.
Beijing has predicted it will take three years to rebuild devastated towns and villages across Sichuan.