Study On Bearing Mechanism And Construction Technology Of Ultra Deep Thick Single-layer Diaphragm Continuous Wall

With the development of society and the advancement of construction technology,the exploration of underground space is getting deeper and deeper.As a relatively stable supporting structure,the underground diaphragm wall applies the experience of building shallow underground diaphragm walls to ultra-deep and ultra-deep.Some unknown risks may occur in thick underground diaphragm walls.Based on the design and use of ultra-deep and ultra-thick underground diaphragm walls,this paper analyzes the stress mechanism of the slot formation phase and the use phase,and combines the finite element method.The analysis software dynamically simulates the process of forming and using the underground diaphragm wall,compares and summarizes its stress characteristics,and makes recommendations for the construction of ultra-deep and thick underground diaphragm walls.The main contents and conclusions of this paper are as follows:(1)In the design and calculation stage,several different soil pressure distribution laws in ultra-deep strata are summarized,and the structure of the underground continuous wall is designed by considering the displacement mode theory and Rankine's earth pressure theory,and the incremental method is adopted.The ANSYS finite element analysis software was used to calculate the structure of the diaphragm wall by simulating the excavation process of the foundation pit,and the displacement and bending moment distribution rules of the diaphragm wall under two types of earth pressure were obtained.(2)During the slot formation phase,FLAC3 D finite element analysis software was used to simulate and analyze the influencing factors of the stability of the ultra-deep slot section,including mud weight and slot section length.It can be obtained by shortening the slot section length and increasing the mud specific gravity.Effectively increase the limit depth of trench excavation.Among them,when the slot length of 6 m is preferentially adopted,it is not enough to dig to the design depth of the slot section,but by shortening the slot length to 4 m,the design depth of the slot section can be reached.(3)Combined with the construction steps,construction facilities and design specifications of underground diaphragm walls in general,the equipment,mud configuration,and verticality testing for the formation of ultra-deep and thick single-story walls are studied.The lifting steps of super-long and heavy-weight steel cages and the selection of the lifting length were studied.The quality control measures for the filling of large-volume concrete and the waterproof measures for the joints between the ultra-deep underground continuous walls were analyzed.Suggestions for the construction of thick underground diaphragm walls.