On October 27, Mr. Phan Thanh Nghiem, Deputy Director of the Department of Science and Technology (KH-CN) of Quang Binh province, said that this unit and related departments had just organized a team to survey and assess the cause of an unusual sinkhole in a resident's garden.
Accordingly, this "death hole" appeared in Mr. Ho Binh Hien's garden in Km41 village (Ngan Thuy commune, Le Thuy district), the hole's mouth diameter is up to 4.2m, and it is up to 12m deep.
This hole is only about 3 meters from Mr. Hien's kitchen foundation and about 100 meters northwest of Provincial Road 10.
According to Mr. Hien, after many days of heavy rain, the land in his garden suddenly sank and rose. After a while, this "death hole" suddenly appeared, inside the hole there was a lot of clear blue water.
After receiving the report from the people, the Department of Science and Technology coordinated with the Union of Science and Technology Associations, the Department of Natural Resources and Environment of Le Thuy district, and geological experts to go to the scene to survey and assess the cause of this phenomenon.
According to the assessment, the area of Mr. Hien's house has a layer mainly of clay and clay mixed with a thickness of about 7-20m, the bedrock (limestone) surface is at an uneven depth of 7-20m, on the geological structure of the Devonian system and the Cobai system, including limestone and limestone mixed with Dolomite.
This ground is a type of slope soil, some remnants are formed on the limestone below. When the limestone below this sinkhole undergoes karstification, it forms holes, caves, hollows... when there is heavy rain, it creates a large flow in the caves, hollows causing the upper layer of soil to subside.
The survey team recommended using sand and gravel to fill the sinkhole, let the sand settle naturally for a period of time, and when the sand and gravel subside, continue to fill it up... until a period of stability is reached, then complete the project.
If the above solution does not create surface stability and subsidence continues, it is recommended to report to the relevant agency to study the next solution. The Ngan Thuy commune government has zoned the area where the subsidence occurred and warned of the danger.
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