Experimental Study On Internal Force And Deformation Of Pile Anchor Supporting Structure Of Deep Excavation Pit Under Natural Frost Heaving

In Qinghai area,the temperature is low in winter.When the temperature is low to the freezing point of water in the soil,the freezing of the soil leads to its volume expansion,which increases the stress and deformation of the supporting structure.To discover the have an influence on of iciness soil frost heave on the inner force and distortion of deep groundwork pit pile-anchor aid in Qinghai location in iciness,the field test of pile anchor support in a site of Xining city was carried out.The endogenous force and drift of supporting structure are monitored,and the interplay law between soil frost heaving and endogenous force and go with the flow of helping structure is analyzed by means of combining air temperature,soil temperature and water content.Furthermore,based on the background of field test,plaxis-2d software is used to simulate the thermal mechanical coupling of the pile anchor support of the foundation pit,and the modifications of endogenous force and drift of the pile anchor assist below extraordinary temperature prerequisites are analyzed respectively.Compared with the test results,the relationship between the frost heaving effect of soil and the inside pressure and distortion of deep basis pit pile anchor aiding shape is further got,which affords some theoretical guide for basis pit engineering in comparable local weather areas.Through the study of this paper,we get the following results:(1)Combined with the comprehensive analysis of atmospheric temperature and rate of water content,it is concluded that the surface soil temperature is appreciably affected by way of the atmospheric temperature and decreases the fastest,and-10℃and 0℃ are the mutation points that affect the soil temperature trade.With the expand of water content material in the floor soil,the earth pressure in this phase will aggrandize sharply,which leads to the most version vary of stress and bending second in the higher part of the supporting pile.(2)With the continuous decrease of air temperature,the stress top cost of the top bolt is larger than that of the lower bolt due to the vertical and horizontal freezing action of shallow soil.The constraint of the crown beam on the upper bolt makes the stress of the upper bolt decrease,and the stress of the lower bolt increases due to the continuous low temperature.The stress variant of pile is in the main targeted in the upper phase of basis pit.The displacement of supporting pile is positively correlated with the change of temperature,and the morph increases with the duration of frost heaving,and finally increases by 57.7%.By comparing the test results under frost heaving and non frost heaving conditions,it is observed that the variant values of soil pressure,pile stress and bending second,pile displacement under frost heaving conditions are greater than those under non frost heaving conditions,which further verifies that the frost heaving effect of soil will increase the stress of support structure and aggravate its distortion.(3)Comparing the numerical simulation consequences of Plaxis-2D with the test results,it can be concluded that the simulation effects are roughly steady with the test consequences.When the soil temperature drops to a positive value,the typical distortion of the basis pit will expand.With the increase of frost heaving time and times,the stress of the supporting pile is concentrated in the middle and lower part,and the axial force of the lower anchor gradually increases.