| With the accelerating development of urbanization in China, the utilization and development of underground space has become the main method to solve the scarcity of construction land resource. Therefore, the trend of a numbers of foundation pit engineering is towards a direction of deeper, bigger foundation pit and more complicated surrounding environment. And the complicated surrounding environment has brought two problems:(i) in order to avoid the restriction of surrounding buildings and pipelines, the shape of the foundation pit tends to be quite irregular, and considering the objectively existing foundation pit spatial effect, which is obviously evident especially for irregular-shape foundation pit, the transformation of different parts under the same maintenance condition can make a huge difference. The conventional design method of foundation pit always adopts the two-dimensional plane analysis method and uses the typical profile for analyzing, but it can’t reflect the real three-dimensional damage of the foundation pit. Therefore, the study on the foundation pit spatial effect has great significance for engineering application;(ii) on the other hand, the processing of the urban foundation pit engineering will inevitably bring side effect to the normal use and operation of surrounding buildings, pipelines, roads and also to the live and work of the surrounding residents, without a proper control, it is likely to cause a series of environmental, economic and social problems. Therefore, it has an important practical meaning to establish a guiding system for dealing with the relationship between the foundation pit engineering and its surrounding environment. Based on the above situation and depending on the Deep Foundation Pit Project of Hanbin First Hospital in Ankang, the research content of this article is as follows:1) To establish the three-dimensional damage analysis model and take the cohesiveness soil as research objective. On the basis of Mohr-Coulomb strength theory and the utilization of the soil plasticity upper-bound theory and the limit equilibrium theory, to deduce the calculation formula of the active earth pressure of inner corner,external corner and middle pit wall section of the foundation pit.By comparing the earth pressure under the spatial effect and that under conventional plane analysis, to deduce the calculation formula of the spatial effect influence coefficient. And by using the deduced formula, to explore the influence law and factors to the spatial effect coefficient, such as the foundation pit depth, the distance to the corner and the angle ofthe external corner of the foundation pit;2) By establishing the numerical simulation through FLAC3 D software, to analyze the spatial effect of the inner corner and external corner of the foundation pit, and explore the changing rules of the foundation pit spatial effect under different calculation part and calculation depth. And by comparing and analyzing the numerical simulated result with the theoretical result, to verify the general rule of the spatial effect;3) To introduce the environmental symbiotic concept into the urban foundation pit engineering system and select the typical index according to the engineering’s own characteristics, then adopt the analytic hierarchy process to determine different evaluation factors’ weight and use fuzzy comprehensive evaluation to evaluate different object levels. Taken together, to establish an environmental symbiotic evaluation system for urban foundation pit engineering;4) By using the deep foundation pit project of Hanbin Hospital in Ankang as practice, to design the support structure based on the space effect and use the monitoring data to compare with the theoretical deduction result.5) To analyze and verify the influence rule of the foundation pit spatial effect, and give a beforehand control evaluation to the environmental symbiotic situation and the completion evaluation to the environmental symbiotic situation of this project. |
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