Non-contact Experimental Study On Interaction Between Ecological Granary Silo-soil Under The Action Of Groundwater

The underground silo is a kind of ecological granary with energy saving,land saving and green,which has the advantages of restraining grain pests,mildew and delaying grain aging by using the natural environment such as closed,low oxygen and constant temperature.However,in the construction and operational process,affected by complex geological and hydrological conditions,the deformation of the underground silo and the soil around the underground silo is extremely complex under the action of the rising groundwater level,cause instability and damage such as the collapse of the soil around the silo,the overall floatation of the silo,and even the overturning.The interaction between the underground silo and the soil around the silo is the key to the safety and stability of the underground silo.Based on the National Natural Science Foundation of China（No.51578216,No.51978247）,this paper developed a set of non-contact test system for the interaction of underground silo and soil around the silo under the action of groundwater.Using this system,the effects of different relative compactness soil on the displacement of underground silo and the deformation of soil around the underground silo under the action of groundwater were investigated.The specific research contents and main conclusions are as follows:（1）According to the field investigation results,a set of non-contact test system is developed.Creo modeling and 3D printing technology are used to make the scale model of underground silo;According to the requirements of imaging plane visualization,the generalized geological model slot was made;Considering the groundwater action,the"back shaped"water supply pressure system is made.According to the field of view and working distance determined by the test,Video Gauge^TM system and particle image velocity measurement system for soil deformation measurement are selected;The measurement accuracy of the system is analyzed,and the relative error is verified to be 1.25%,which meets the requirements of the test for measurement accuracy.The experimental system provides a new method for studying the interaction between underground silo and soil under the action of groundwater.The experimental system provides a new research method for the interaction between soil and structure under the action of groundwater.In this paper,three soils with different densities will be selected as the surrounding soils,respectively loose,medium and dense,and the experimental system developed is used to study the displacement of silo and the deformation of soil around the silo under the action of groundwater.（2）Arrange the target points at equal intervals along the middle of the model silo,and use the Video Gauge^TM system to record the coordinates of the target points in the silo in real time.The pixel equivalent method is used to convert and optimize the measured data,draw the displacement time history curves of the underground silo in the vertical and horizontal directions under different working conditions,and compare and analyze the influence of the relative density of soil on the displacement of the underground silo.The main conclusions are as follows:Under the action of groundwater,the displacement of the silo body in the vertical direction changes greatly,and the displacement in the horizontal direction is smaller;when the groundwater level is the same,the relative compactness of the soil around the silo body is greater,the displacement of the silo body is smaller,and the displacement-time history curve is smoother;The stronger the soil system’s ability to resist the buoyancy of groundwater,the better the stability of the entire warehouse-soil system under the action of groundwater.（3）On the basis of（2）,collect serial images of soil deformation under different working conditions,and the images are processed by MatPIV software to obtain the displacement nephogram and displacement vector map of soil around the underground silo in the floating stage,tilting stage and instability stage.The micro movement law of soil particles around the underground silo under different working conditions is studied,and then the deformation law of soil around the underground silo is obtained.The main conclusions are as follows:With the rise of groundwater level,when the soil around the underground silo is loose,the deformation range diffuses to the far distance around the underground silo,showing an obvious"inverted triangle";When the soil is medium dense,compared with the loose state,the soil deformation changes from the whole deformation to the local deformation,and the maximum area is concentrated at the junction of the conical bottom and the wall and above.When the soil is in the dense state,compared with the loose state and the medium dense state,the disturbed range of the soil is significantly reduced,and the soil deformation is concentrated in the symmetrical area on both sides of the underground silo wall.（4）On the basis of（2）and（3）,Based on the theory of lateral earth pressure on retaining wall,Taking the soil around the underground silo as an example,the interaction between underground silo and soil around the silo under the action of groundwater is discussed theoretically.The results show that:under the action of groundwater,with the increase of the displacement and inclination of the underground silo,the soil deviate from the inclined direction of the underground silo loses the support of the underground silo,and the soil reaches the initiative limit state.At this time,the earth pressure on the inclined side deviate from the underground silo reaches the minimum value;When the soil in the inclined direction of the underground silo is squeezed and the inclined side of the underground silo is subjected to passive earth pressure,the movement of sand around the underground silo increases continuously,reaching the passive limit equilibrium state of sand,and a continuous sliding surface appears around the underground silo,At this time,the sand deformation around the underground silo expands from local deformation to overall deformation,the underground silo soil stability system is destroyed,and the underground silo structure is unstable.