| With the acceleration of urbanization,the demand for urban underground space in China is increasing.As an important technology of foundation pit support,diaphragm wall has the advantages of low construction vibration,low noise,suitable for urban construction,large wall stiffness and good anti-seepage performance.Accordingly,the traditional diaphragm wall also has many disadvantages.Due to the poor pouring environment,the wall quality is not easy to guarantee,and there are phenomena such as concrete mud inclusion,exposed reinforcement,irregular water seepage on the wall and so on.Its complicated construction process also makes the construction period of underground diaphragm wall longer and increases the construction cost.In order to make up for the shortcomings of the traditional cast-in-situ diaphragm wall,comply with the development trend of building industrialization,promote the transformation and upgrading of relevant industries,and meet the increasing requirements of foundation pit support engineering in terms of safety,construction speed,energy conservation and environmental protection,this paper proposes a dry connected fabricated grid diaphragm wall,which can be built with excavation machinery,Realize the construction process of excavating while forming the wall,greatly simplify the construction process of underground continuous wall,effectively ensure the wall quality,shorten the construction period and reduce the hoisting difficulties caused by the self weight of prefabricated wall.In order to fully understand the mechanical properties of the new fabricated diaphragm wall,this paper will study the waterproof performance and overall mechanical performance of its joint,and put forward the optimization design method of the wall based on this,so as to provide a basis for practical engineering application.The main research work of this paper is as follows:(1)A new type of dry connection fabricated grating diaphragm wall is proposed.The design idea of its section form,horizontal joint and longitudinal connection is described in detail,and the fast construction process of slotted retaining wall is put forward according to its section characteristics.(2)The waterproof performance of fiber reinforced cement-based composite(ECC)used at the joint is experimentally studied.In this paper,the better waterproof and impermeability performance is obtained by adding silicone waterproof agent,silica fume and nano silica to ECC.The water saturation test,capillary water absorption test and impermeability test of ECC specimens with different admixtures are carried out,and the test results are compared,It provides a reference for optimizing formula design.(3)A bolt dry connector with full main reinforcement connection is designed and its reliability is verified by numerical simulation.Based on ABAQUS finite element analysis software,this paper studies the mechanical characteristics and tensile strength of the new connector,analyzes its parameters,and realizes the optimal design of the connector.(4)The mechanical properties of dry connected fabricated grid diaphragm wall are analyzed by finite element method.Based on ABAQUS finite element analysis software,this paper studies the interface bearing capacity and stiffness of dry connected fabricated grid diaphragm wall,as well as the lateral displacement and joint failure of the wall under lateral pressure,and comprehensively analyzes the influence of various parameters on the performance of the wall.(5)The design and calculation method of dry connection fabricated grid diaphragm wall is proposed.Based on the relevant provisions of the current national standards,this paper puts forward the calculation methods of the flexural capacity of the normal section and the shear capacity of the fabricated joint,and compares them with the finite element calculation results.Based on the above research,the innovations of this paper are as follows:(1)A new type of dry connection fabricated grating diaphragm wall,which is different from the traditional cast-in-situ diaphragm wall,is designed,and its design idea and advantages compared with the traditional diaphragm wall are expounded.(2)The new material ECC is introduced as the waterproof joint material to improve the waterproof and impermeability by adding materials,and optimize the material formula.(3)The mechanical properties of connectors and walls are explored and verified by means of soft finite element analysis,and the parameters that may affect the mechanical properties of walls are comprehensively analyzed.The calculation method of bearing capacity of dry connected fabricated grid diaphragm wall is proposed,which provides a basis for design and application. |
