1) Assessment of surface subsidence in Red River Delta when mining and post-mining brown coal;
2) Proposed measures to reduce the harmful effects of subsidence and subsidence due to mining brown coal.

Theoretical results:
1) The first time the author has used the finite element method for calculating surface subsidence due to mining in Vietnam. This is the Geomechanical problems for large regions and many scientific tricks is applied to solve the problem.
3) Evidence of the impact of brown coal mining to the safety of dykes and roads as well as other predicted impacts to the construction.
4) Determining groundwater levels drop when drying mines in the mining process and land subsidence due to groundwater decline respectively.
Applied results:
1) Evidence is land subsidence caused by mining brown coal in the Red River Delta. This is a hot issue today. The subsidence 0.25 m to 1.60 m depending on whether or not the post-mining backfill.
2) Proposing the change of geological environment and its implications to socio-economic activity in Red River Delta while brown coal mining organization.

1) This is a solution to the Geomechanical problems with large region applied to the mining sector and related fields.
2) To solve the problem completely many scientific tricks to use in the specialized science branch and the related scientific fields.
3) Open up the application of mathematics in forecasting the effects of natural and socio-economic activities to change the geological environment. 

Scientific papers in referred journals (list):
Scientific paper 1: Some initial comments of geological environment change when exploiting brown coal in bac bo plain” accepted by J. of Sci. of the Earth.
Scientific paper 2: Forecasting land surface deformation in hadong region due to urbanization and exploitation of groundwater, J. of Sci. of the Earth 35(1), 29-35, 2013.
Patents (list):
Technological products (describe in details: technical characteristics, place):
1) Database: The Quaternery-geological map, geomorphology - neotectonic, geotechnical and hydro-geological maps in region proposed mining brown coal 1:25.000-1:50.000 rate (notes Archive in the subject).
2) Geological Engineering cross section of the area proposed brown coal mining (Notes Archive in the subject);
3) Model for calculation problem setup (Notes Archive in the subject);
4) The results of land subsidence (Notes Archive in the subject), including:
• The results of the soil deformation mainly;
• The results of stress-strain analysis;
• The results of land subsidence;
• Forecast ground deformation results.