Study On The Application Of Anti-floating Method In Basement

With the development of urban underground space,the underground building area is increasing,and there are more and more problems in basement due to the disadvantage of anti-floating.In engineering,passive anti-floating methods such as weight method,antifloating anchor and anti-floating pile are often used to solve the anti-floating problem of basement.Compared with the traditional methods mentioned above,the active anti-floating measure of water release and decompression has the advantages of convenient construction,no impact on the construction period and low cost.Although it has been preliminarily applied in the project,the understanding of its influence law is not enough,which restricts the popularization and application of this technology.Therefore,it is of great theoretical and practical significance to deeply study the influence law of the factors affecting discharge decompression and anti-floating.The main research contents and conclusions are as follows:(1)A test device is designed to carry out model test on the process of water release and decompression in the basement,and the specific influence of several factors on the effect of water release and decompression is analyzed.It is concluded that the best layout of drain holes is uniform layout,and close to the bottom plate as far as possible,and there is a reasonable range of drain hole spacing.(2)In this thesis,the finite element software COMSOL Multiphysics is used to model and analyze the decompression process of the basement.Five factors that affect the antifloating effect of the decompression are studied: the number of drainage holes,the height of the drainage holes,the layout of the drainage holes,the permeability of the filling soil and the width of the filling soil.The results show that the optimal distance between discharge holes is 2-3 m.The best layout is that the outlets are evenly distributed and close to the bottom plate.The width and permeability of fill have great impact on the environment.The smaller the width of fill,the better,and the lower the permeability of fill,the better.The main factors affecting the anti-floating effect of water release decompression are the permeability of fill,the width of fill and the spacing of drain holes.(3)In this thesis,the anti-floating design of a basement project under construction is carried out.The orthogonal test method is adopted to calculate the three main factors affecting the effect of water release and decompression: the spacing of water release holes,the width of filling soil and the permeability of filling soil.Taking the pressure head of the bottom plate and the water level drop at 0 m of the outer wall of the basement as the test indexes,the results are analyzed by range and variance.The results show that the primary and secondary order of the factors affecting the method is: fill permeability,fill width and drain hole spacing,and the optimal design scheme is obtained.