Compacted fill foundation on soft soil layer is widely used as a kind of heterogeneous foundation. But few studies are conducted on the failure mode and bearing capacity mechanism of this kind of foundation. The depth modified coefficient is taken as 2 in geotechnical engineering practice. Finite difference method is used to establish a numerical model

and then the factors that affect the depth modified coefficient of the bearing capacity of compacted fill foundation are studied. Furthermore

a comparison with the values of the current standard recommended method is made. The results show that the deeper the soil is

the larger the foundation load is

the larger the volume of the soil is

the greater the bearing capacity of the foundation is. With the increase of soil width

the ultimate bearing capacity of the foundation increases firstly and then tends to be stable. The increase of the frictional angle in the sand can also increase the ultimate bearing capacity of the foundation. Generally

the recommended value of the specification is conservative

which will cause the waste of the bearing capacity while the strength of the underlying layer is very small

the recommended value may overestimate the bearing capacity of compacted fill foundation

leading to a risk to safe for engineering

thus in the project design

it should be taken into consideration.