Coastal Geological Conditions The Gushing Water And Sand Base Research

With the development of the construction of the coastal cities, deep excavation of foundation pit is present, which is associated with the complex problems of groundwater, groundwater seriously threatens the safety of foundation pit in all aspects. Especially in the coastal area, the foundation pit are near the sea, there is a certain degree of hydraulic relationship of groundwater and seawater. So the groundwater problem of coastal foundation pit is more complex compared to ordinary pit, concrete embodiment in the basement of the gushing water and sand, the basement uplift, the collapse of the slope, etc. This article mainly aims at the gushing water and sand foundation pit base in a coastal area problem.I list the typical cases of coastal area under the geological base of the gushing water and sand problem analysis and research.The main research contents include:(1)Introduces the general situation of the engineering case, geological features, basal sand gushing water problems, and analyse the characteristics of gushing water and sandeach problem;(2) According to the typical case, summarizes the characteristics of coastal geology, that soil is uneven, uneven soil, groundwater influenced by the sea;(3) According to the distance of the foundation pit and sea water plane level and the difference of basal soil layer, categories for foundation pit;(4) Qualitative proposed coastal geological factors affecting the gushing ater and sand, and to build finite element modeling and numerical analysis of concrete quantitatively, including sealing curtain length、the horizontal distance of Overbreak and curtain、collecting well set etc;(5) On the basis of numerical computing and data analysis and calculation of the critical thickness of basement, Sums up the relationship between the influence factors and the basal critical thickness.Through this study reached the following conclusions:(1) The underground length of stop water heavy curtain affect the change of the critical thickness. When not deep bedrock, the longer the sealing curtain, critical thickness is smaller, when the depth under bedrock, the critical thickness basically unchanged;(2) when thehorizontal distance of the set of wells and overbreak location is in the range of 5m, the closer the distance, the bigger the critical thickness. After more than 5m, critical thickness basically unchanged;(3) if sump excavation depth control within the weak permeable layer, the greater the depth, the smaller the critical thickness; collecting well pumping rate control in 1e-5 m/s is more appropriate, and should be less than a confined aquifer permeability coefficient of soil;(4) When the basement is concreting, the construction of foundation pit size about 1/2, should pay attention to the change of groundwater level, should increase drop equipment when necessary,reduce the level of water that underground.Finally oceanal area foundation pit occurs when the gushing water and sand of different construction technology for emergency response, and the feasibility is calculated on the basis of the theory, combined with the actual construction process,the apply theory to practice.