The bottom-supported platform for offshore wind power

suitable for soft soil areas of the sea

has gained popularity with increasing total installed capacity of offshore wind power. The platform is anchored on a mat foundation through a supporting structure

which evenly distributes the concentrated load into the seabed foundation

providing essential support for the offshore wind installation platform. Due to long-term bottom-sitting

the soil beneath the foundation consolidates

increasing the difficulty of foundation recovery or relocation. Therefore

a new hollow square-shaped mat foundation structure is proposed. To investigate the vertical bearing capacity characteristics of this new type mat foundation in saturated soft clay

centrifuge vertical bearing capacity tests were conducted. Additionally

finite element numerical analysis was employed to study the effects of open porosity and normalized strength on vertical ultimate bearing capacity. The results indicate that the American Petroleum Institute (API) standards underestimate the vertical bearing capacity of foundations when the normalized strength of soil is less than 2

and overestimate it when it exceeds 2. Furthermore

the vertical ultimate bearing capacity gradually decreases as the open porosity increases. However

linearly reducing the effective area according to API standards is inappropriate. A formula considering the open porosity and normalized strength as variables is presented for calculating the vertical ultimate bearing capacity of hollow square-shaped mat foundation

serving as a reference for practical engineering.