Groundwater Uplift Mechanism Study Under Complex Urban Environment

With the economic developing rapidly, urban space has become increasingly scarce, which caused an upsurge of underground space development. However the safety of the underground structures are, without exception, subjected to dynamic changes in groundwater, which arises a series of new geotechnical problems, a remarkable one of which is how to adopt the load value reasonably on the side wall and the bottom of foundation of the underground structures. Carrying out the study on groundwater uplift action mechanism and underground structure uplift load value-adopting systematically, have important scientific significance and strong academic values, the results of its research has important projects significance and broad application prospects to guide the design of anti-uplift, reduce unnecessary capital and material inputs and ensure the safe operation of the construction.Based on the above engineering background, the study subjects using information investigation, theory analysis, model experiment, in situ testing combined research methods, took the interaction mechanism of groundwater and underground structure and reasonable calculation model of groundwater's uplift as the study main line under different hydrogeological conditions and engineering background in Beijing area, based on extensive research work generalized the reasonable geological concept model, and on the basis of which, different scale model tests was designed, reasonable calculation model was advanced, a suit of anti-uplift optimization evaluation system was set up, and all this provide a reasonable reference to determine underground structure's uplift pressure. Main research of the topic included:1. Hydrogeological condition and groundwater's existing characters in Beijing downtown areas was studied, based on which, shallow groundwater which has direct impact to anti-uplift problem of groundwater was divided into several areas, and groundwater macro features in every divisional were summarized, in different area different representative geological concepts models was set up.2. Different scale model testing devices was developed, and a software systems to monitor and collect and real-time analysis the pore water pressure data was developed.