Study On The Crack Mechanism And Pre-control Measures Of Rammed Earth Houses

The rammed earth house is built with unfired soil as the main construction materials, and with the row soil wall reinforced layer by layer as the main load-bearing elements of construction. Rammed earth houses are built with local materials. The original soil are unfired, so it is energy saving, environmentally friendly, and low cost. Rammed earth walls can be well isolated from the summer heat outside, also effective against the winter chill outside invasion. In addition, the construction waste removed from the rammed earth house can be directly return to the farmland, in order to achieve recycling and ecological balance, which makes the rammed earth construction has strong vitality.However, rammed earth houses in the village are self-built by the villagers. What time to built houses, which kind of structure to choose, etc., entirely depends on the owner’s economic strength, the local customs and the experience of building craftsmen. The villagers are not consciousness in disaster prevention, and are lack of knowledge of disaster prevention, which causes a lot of structural safety risks, such as the low strength of rammed earth wall, the poor integrity of the rammed earth structure, the weak connection between housing components.Among them, the wall vertical cracks of the rammed earth wall in the vertical and horizontal transfer is a common failure mode. After the junction of the wall vertical and horizontal wall cracks, the vertical and horizontal wall’s rachel between them will be weakened, and the integrity of the housing structure will be undermined. If we left this to development with control, it will lead to major accidents of houses collapsed, and the consequences could be disastrous. In order to study of force-deformation properties of the junction of the rammed earth house’s vertical and horizontal wall, reveal the rammed earth wall’s cracking mechanism, and then verify the effectiveness of pre-control measures, in the support of the National Eleventh Five-Year Technology Support Project (Issue Number:2006BAJ04A02), this paper made the following work: (1) Through field research, we summed up the two structure types and three roof truss type of rammed earth housing, and introduced the existing situation and maintenance repair situation of the local housing. We summarized the rammed earth walls common cracks form, and gave an overview of the causes of various types of cracks and pre-control measures through field investigation and research.(2)In the several common cracks form of rammed earth walls, the probability of occurrence of the crack in vertical and horizontal wall junction is large, which affects the structural integrity and safety, and poses a serious threat to the lives of the tenants and property safety. Therefore, the mechanism of the vertical and horizontal wall cracks were studied in-depth in this paper.(3) In this paper, the method of numerical simulation analysis was adopted. We made a series of assumptions, in order to reflect the main infulencing factors of housing’s stress and deformation, ignoring the secondary factors. On this basis, we establish a rammed earth house finite element model.(4)With the modal response spectrum method, the analysis of numerical model of the rammed earth housing under the dead weight and seismic was made. The law of the whole structure’s force and deformation in X direction and Y direction under the dead weight and seismic was got.(5) Under the dead weight and seismic, the nature and distribution patterns of stress in vertical and horizontal wall junction was inducted, which reveals the internal mechanism of the cracks in this part, and clarifies the process of development of cracks in the wall.(6) We used the method of setting wood ring beam recommended by the national standards, and re-established the numerical model. Compared with the previous analysis, the effectiveness of measures of this construct verified.