Study On Bearing Capacity Of Sandy Foundation Considering Side Load Effect

The bearing capacity of a foundation is one of the most fundamental issues in the field of geotechnical engineering.When the soil undergoes shear failure under external loads,the foundation reaches its ultimate bearing capacity.After more than a hundred years of research,scholars have developed relatively complete and safe bearing capacity calculation rules.With the development of the economy and society,the height of buildings continues to increase,the depth of underground structures gradually increases,and their own weight continues to break records.The requirements for the bearing capacity of the bearing layer are becoming increasingly strict.At the same time,the demand for construction land has skyrocketed,and land supply is tight.Many projects are located on sandy foundations.It has become an urgent task to determine the bearing capacity of a foundation with sandy soil as the bearing layer and a certain burial depth.Due to various calculation rules and design specifications,basic safety is the primary element.For weathered sandstone foundations,the edge load effect is usually not considered and the bearing capacity depth correction is not carried out,resulting in conservative engineering design.In order to explore the bearing capacity of sandy foundations and the impact of edge load effects on them,this article specifically conducted the following research:(1)Using standard sand to fill the model foundation,graded loading tests were conducted under different edge load sizes,and the settlement curve of the bearing plate was obtained.The experiment shows that applying edge loads can significantly improve the bearing capacity of the foundation and limit the settlement of the bearing plate.As the edge load increases,the failure mode of the foundation changes from punching shear failure to local shear failure.(2)The finite element software was used to simulate the failure of the model foundation,and the development and distribution patterns of stress,deformation,and plastic strain in the foundation under different side loads were obtained.(3)Conduct indoor experimental analysis on weathered sandstone samples as the bearing layer of a certain project in Lanzhou,and analyze their physical and mechanical properties;Plate load tests were conducted on-site,and different sizes of loads were applied to the periphery of the pressure plate to simulate the effect of side loads.The results indicate that the weathered sandstone in this site softens when exposed to water,resulting in poor water stability;The bearing capacity is significantly improved under the action of side loads,and it is reasonable to make depth corrections to it;However,the sensitivity of bearing capacity to the size of the pressure bearing plate is extremely weak,and width correction may not be required.(4)The finite element software was applied to analyze the distribution patterns of stress,deformation,and plastic strain of weathered sandstone foundation under different edge load sizes and different edge load ranges.The relationship between bearing capacity and edge load size and range was quantitatively analyzed,and the fitting relationship between the depth correction coefficient and foundation burial depth in this field,as well as the fitting relationship between edge load range and bearing capacity,was obtained.