| In exploitation subsidence, damage process of surface buildings is a complex dynamic process. The issues of building damage caused by mining, more and more arouses people's attention. In the field practice, people care more about the critical state issues when cracks appear in the building. To define the critical value of the building wall cracks, has become a very important research topic.In this paper, synthesizes the knowledge of many disciplines such as mining subsidence, the mechanical, structural mechanics, foundation and so on, and analysis the additional forces caused by surface deformation working on different types of buildings. To simulate the masonry structure of the one-story houses as a model, calculate types of additional forces working on walls, such as the foundation reaction, additional moment, stress, etc. By analysis the stress working on the modle, anti-operator the additional force working on wall, and the surface deformation as unknown value, cracks have just come to the model of wall, the corresponding surface deformation of the critical value. Solve the problem of the value of the surface deformation, when cracks appear on of the masonry structure buildings wall. Rusults as follows:(1) Under the surface horizontal deformation: the critical value of horizontal tensile strain is 0.55mm/m; the critical value of horizontal compression deformation is 1.16mm/m.(2) Under the surface positive curvature deformation: When the curvature deformation for instantaneous changes, the critical value is 0.028 mm/m~2; When the curvature deformation for slow changes, the critical value is 0.056 mm/m~2. Under the surface negative curvature deformation: When the curvature deformation for instantaneous changes, the critical value is 0.042 mm/m~2; When the curvature deformation for slow changes, the critical value is 0.084 mm/m~2.(3) Under the surface inclination deformation: Under the additional moment caused by deadweight, the critical value of wall is 0.656mm/m; when the building inclination, the critical value is 0.851 mm/m.It also systematically studied the dynamic state regularities of distribution of the subgrade reaction and foundation for buildings, and analysis of regularities of distribution and influencing factor of buildings under the subgrade reaction, and analysis of the dynamic subsidence of the building foundation and a major factor of the foundation appeared uninstall.When the cracks appear to the wall, research results of calculation and determination of the critical value for masonry structure building located in mining area, with guidance and application value. |
