Numerical Simulation On Uplift Resistance Of Joint Board Ball Foundation Of The Sandy Ground

With the steady promotion of the programme of “the Belt and Road”in our country,rich wind resources in Hexi Corridor area have been developed and utilized,and large-scale wind farm construction is gradually emerging.However,due to extensive distribution of sand in the Hexi Corridor area and special engineering geological conditions,a new and more secure joint board ball foundation is designed for the engineering construction in this area where contains unsaturated sandy soil.This paper is aimed to research the anti-tensile mechanism of joint board ball foundation with cement soil columns and joint board ball foundation without cement soil columns,ultimate up-lift bearing capacity of joint board ball foundation with cement soil columns and its influence factor.The research results have a certain effect on the study of pull-out foundation.The research and conclusions of this paper are shown as below:(1)Under the effect of up-lift force,the shallow-buried joint board ball foundation with cement soil columns suffers general failure and the failure plane is hook face.The deep-buried joint board ball foundation with cement soil columns with cement soil columns suffers local failure.The ultimate up-lift bearing capacity is confirmed by uplift force-displacement curve of foundation,the uplift process is divided into elastic stage,local failure stage and total failure stage.(2)In the shallow-buried case,monitoring points are set in the soil around foundation to analyze the displacement of surrounding soil and distribution of stress.The larger the distance between monitoring point and anchor cable,the smaller the displacement is.It is consistent with upheaval phenomenon of model test.When the distance between the monitoring point and the anchor cable is the same,the displacement of the soil at the surface monitoring point is the largest,and the other monitoring points are reduced by the shear deformation.(3)Up-lift bearing capacity of joint board ball foundation with cement soil columns is affected significantly by the depth ratio,lower ball diameter and false cohesive force of sand soil.And the influences from elastic modulus of sand soil,theangle internal friction and diameter of cement column are not obvious.(4)This paper simulates the uplift process of joint board foundation without cement soil columns.Under the effect of uplift force,the shallow-buried joint board ball foundation without cement soil columns suffers general shear failure and the failure plane is hook face.The maximum of the shear strain increment occurs in the range of 15° to 45° with the positive and negative X-axis.The deep-buried joint board ball foundation without cement soil columns only suffers local shear failure.(5)When the shallow-buried joint board ball foundation with cement soil columns and the shallow-buried joint board ball foundation without cement soil columns is buried at same depth,and the size is same,they will have same damage form,and nearly ultimate up-lift bearing capacity.