| Underground diaphragm wall is widely used in deep foundation pit engineering because of its large overall stiffness,good water stop performance and adaptability to various complex geological conditions.Circular diaphragm wall is a special form of diaphragm wall,and its most significant feature is the spatial arching effect of circular structure.Due to the influence of construction technology,there are joints in the wall.Therefore,the circular diaphragm wall is not a continuous body in the true sense.The existence of joints will affect the integrity of the wall,and then affect the stress and deformation characteristics of the wall.To intuitive study juncture exists the characteristics of stressed deformation of underground continuous wall,this article has carried on the indoor model test,through the simulation of circular foundation pit excavation,are considering joint internal force and deformation of underground diaphragm wall,discusses the model of lining wall diameter,number of joints,the influence of factors on the behavior of underground continuous wall work.With the development of computer technology,numerical calculation has become the main method to study diaphragm wall.In this paper,ABAQUS numerical software is used to simulate and analyze the mechanical characteristics of diaphragm wall excavated step by step in the model test.,considering the number of joints,wall diameter,with or without lining and other conditions,a number of calculation models were established,and the feasibility of setting up the joint element was verified by comparing the measured and calculated values.The results show that:(1)When joints exist,the circular diaphragm wall still has a significant "spatial arching effect",and the wall will produce a large toroidal compressive stress,which is significantly greater than the vertical stress.(2)Due to the influence of "spatial arching effect",the lateral displacement of the wall is small,and the settlement of the soil outside the pit is small.The change law of circumferential stress is basically the same as that of circumferential displacement,showing a distribution form of large in the middle and small at both ends.(3)The vertical displacement of the wall with a diameter of 30cm and the vertical stress of the wall with a diameter of more than 60cmare opposite to the circumferential displacement and stress.The smaller the number of joints,the greater the overall stiffness of the wall,and the stronger the inhibition effect of soil on the wall.The internal force and displacement of the diaphragm wall are restrained to some extent by the application of inner lining.Due to the small size of the diaphragm wall studied in this paper,the influence of inner lining on the stress behavior of the diaphragm wall is very small,and the role of inner lining is not particularly obvious.(4)The variation trend of calculated values and measured values is basically consistent,which indicates that the joint element set in this paper is feasible. |
