Compressive bearing characteristics of metal grillage foundation in aeolian sand areas

The metal grillage foundation for transmission lines has good application prospect in the aeolian sand areas with harsh environment. To explore the compressive bearing performance of the metal grillage foundation in aeolian sand, 4 groups of true-type tests are carried out. The varying features of the vertical settlement and horizontal displacement at the top of the foundation, the stress of foundation components and the soil stress under the foundation, are all monitored, and then the ultimate bearing capacity of the foundation is analyzed. The results show that the foundation is in the compression-bending state under the combined loads, the ultimate bearing capacity is 1256 kN, and the lateral friction resistance accounts for about 33.5 %. When the compressive load is added to 1632 kN, the foundation has not yet reached the limit state. The horizontal load has an influence on the development of the support stress and the distribution of the soil stress under the foundation, and weakens the ultimate bearing capacity. The existence of surface frozen soil layer produces "frost-heaving restraint" effects on the foundation, enhancing the anti-deformation capability of the foundation. The bearing capacity of the foundation under the compressive loads calculated according to the effective contact area is closer to the measured value. Using the R. Ganesh theory, a method to obtain the ultimate bearing capacity of the foundation under the combined loads through the reduction calculation of the ultimate bearing capacity under compression is proposed. The research results may provide reference for the engineering design and application of the metal grillage foundation in transmission projects in desert areas.