Numerical Simulation Analysis Of Bearing Behavior Of Multichamber Closed Diaphragm Wall Foundation

As a supporting structure,the multi-chamber diaphragm wall has had a far-reaching impact on many major projects in China,but its application as a vertical bearing component is very few,When it is used as a foundation,it is very different from the supporting structure form and bearing behavior,the complex geometric structure and vertical bearing behavior make it as the initial application stage as a foundation.In order to promote the application of multi-chamber diaphragm wall foundation,provide guidance,this paper firstly analyzed the vertical bearing characteristics of single-wall and rectangular-closed-chamber by using numerical simulation method based on the field test;Secondly,the vertical bearing characteristics and displacement characteristics of two-chamber,four-chamber and six-chamber with the same lattice room size were carried out step by step;Finally,according to the vertical bearing characteristics of the multi-chamber foundation,a simple formula to judge the vertical bearing capacity of the multi-chamber was proposed and verified by the monitoring report of P₉ foundation of Qingsen harbor bridge,systematically analyzed the bearing capacity and mechanism of multi-chamber diaphragm wall foundation,and discusses the advantages and disadvantages of the increase of the number of lattice room on the bearing capacity of the foundation.Through the above work,the main results of this paper are as follows:（1）The reliability of the model was verified by comparing the load settlement curve of single-wall with that of field test;The vertical bearing behavior of single-wall and closed-chamber with the same groove thickness under the same geological conditions was compared:There are many excellent bearing capacity of single-wall and rectangular-closed-chamber when they are used as foundation,but the bearing capacity of rectangular closed wall is more complex than that of single wall due to the existence of inner wall core;Because the compression capacity of soil is better than the shear capacity,there are great differences in the exertion of the forces.（2）The vertical bearing characteristics of two-chamber,four-chamber and six-chamber with the same lattice room size were compared,according to the simulation results:The increase of the number of lattice room leads to the phenomenon of stress overlapping,and makes the four forces present complex spatial distribution,which restrains the exertion of end resistance and inner friction;The chamber efficiency of six-chamber is 78%.On the one hand,increasing the number of chamber will cause a waste of bearing capacity,but on the other hand,it will increase the overall stability of the foundation and reduce the settlement.（3）Compared the two-chamber,four-chamber and six-chamber horizontal displacement characteristics:Increase the number of lattice room,it has little effect on foundation settlement but significant effect on horizontal displacement,for the soil on both sides of the foundation,the horizontal and vertical displacement effect is very significant,and the effect is not is linear positive correlation with increasing the number of lattice room,also manifests the same as the vertical bearing capacity of the law.（4）Consult the method that offering in the Code for building pile foundation,according to the vertical bearing behavior of multi-chamber,propose the vertical bearing capacity calculation formula,and compared with the value from calculation formula、monitoring report of P₉ foundation of Qingsen harbor bridge and ultimate bearing capacity by numerical simulation,they are close.So it can be used to judge the vertical ultimate bearing capacity of multi-chamber foundation.