Spatial-temporal Evolutional Mechanism And Statistical Characteristics Of Diaphragm Wall Deformation In Metro Station Construction

In the construction of the deep foundation pit of the subway station,the deformation control of the foundation pit is one of the key problems that not only related to the foundation pit itself but also the surrounding building environment.However,the foundation pit engineering has significant difference,and the different engineering has different deformation traits.Because of the complexity of the lateral deformation of the wall,it is difficult to get the analytical solution.There are many assumptions in the numerical simulation.Therefore,it is necessary to study the spatiotemporal regularity and its statistical characteristics based on the long-term monitoring data.Based on the actual engineering situation,this paper takes the measured data of the continuous wall deformation at the construction site as the research object.By analyzing the construction conditions in detail,the transversal deformation of the underground continuous wall is classified,and the spatial evolution law and time evolution rule of the continuous wall deformation is studied deeply.The results of wall deformation were analyzed statistically,and the main conclusions are as follows:(1)In the subway station construction process,the time effect of lateral deformation of the underground continuous wall can cause large deformation,but the excavation of the foundation pit is the main reason for the accelerated development of the wall deformation.(2)The deformation of the continuous wall is not only affected by the excavation construction,but also the interaction of the foundation pit shape,the soil reinforcement and the surrounding environment.According to the engineering practice,in this paper the deformation of the wall is divided into three type: reverse bending deformation,cantilever deformation,reciprocating deformation.According to the evolution type,the reverse bending deformation can be subdivided into reverse bending type a,reverse bending type b and reverse bending type c.By the role of strong support of the foundation pit,all kinds of deformation include different degrees of pit deformation occurred outside the pit.(3)For spatial distribution of transverse deformation of deep foundation pit continuous wall in subway station,the reciprocating deformation is concentrated in the corner of the foundation pit.For the area where the outer soil is reinforced,the continuous wall is mainly composed of the reverse bending deformation.The cantilever deformation is mainly distributed in the area where the soil is not strengthened.(4)The time distribution of the transverse deformation of the deep foundation pit of the subway station shows that the deformation of the continuous wall at different depths can be summarized as four stages in the whole monitoring period: small amplitude fluctuation stage,deformation accelerated development stage,deformation transition stage,deformation and stability stage;under normal circumstances,the deformation of the continuous wall at the end of the deformation accelerated phase reaches the maximum and the final deformation,and the wall deformation is basically stable after the completion of the construction of the floor.(5)Based on the statistical analysis of the transverse deformation of the continuous wall,we obtained the statistical relationship between the maximum deformation,the maximum deformation depth and the excavation depth,and at the same time the distribution probability is studied.The results of this paper can provide reference for deep foundation pit construction in Wuhan area and similar subway station.