Study On Deformation Law Of Foundation Of Non-uniform Filling And Excavation Site In Loess Area

In recent years,with the rapid development of the western region,its engineering construction has been pushed to a new height.Loess and loess-like soils widely exist in the western region have caused many problems in the engineering construction in these areas.Due to the great difference in the topography of the western region,loess is widely distributed and soil erosion is serious.In order to ensure the construction area and expand the construction site,a large area of non-uniform filling and excavation site with large thickness has gradually emerged in the increasing construction projects.Although the emergence of these sites alleviated the problems of land shortage and urban congestion,the corresponding diseases related to ground deformation also appeared.It is urgent to study the problems related to the large-thickness filling and excavation sites in the Loess area.Based on Lanzhou Jiuzhou City Residential District Foundation Deformation Treatment Project,this paper uses MIDAS-GTS geotechnical software to simulate and study the related diseases of non-uniform filling and excavation site,and puts forward the engineering measures for the project and verifies them by numerical simulation,aiming at similar non-uniform filling.The design,construction and deformation prediction of excavation site provide practical engineering significance.The main conclusions of this paper are as follows:(1)Firstly,the deformation law of non-uniform filling and excavation site under the action of dead weight,loading and immersion under different filling modes is simulated and calculated.After analysis and study,it can be concluded that dead weight,loading and immersion have little influence on strongly weathered sandstone and weathered sandstone,which can be neglected;whether it is horizontal filling,oblique filling or step filling,the total variation of filling mode on soil mass can be neglected.The influence of shape is less;the settlement deformation of soil accelerates under loading conditions,but the influence of deformation caused by additional load on the filling site is smaller than that of natural settlement.It can be seen that loading only affects the settlement rate of soil;after the soil is immersed in water,the settlement deformation of the site increases sharply,which indicates that immersion has a great influence on the non-uniform filling site in Loess area.(2)By analyzing the influence of filling methods on the settlement and deformation of the site,the overall deformation law of the large-thickness filling and excavation site under different topographic conditions,which is subjected to dead weight,additional load and immersion action,is studied.The simulation is mainly divided into horizontal,gully and step sites.After filling,the law of settlement or collapsibility deformation of the filling site is analyzed under three kinds of topographic conditions.From the analysis,it can be seen that settlement deformation occurs at the maximum depth of the filling under the three fillingmethods.The effect of dead weight and additional load on the total settlement of the filling soil is small,and the filling site can be improved in construction.Pre-pressure is used to reduce or eliminate the deformation of the filling site under the action of immersion,which shows that the waterproof and drainage measures must be taken in the construction of large thickness filling site in Loess area.(3)Combining with the numerical simulation calculation of different conditions and working conditions of the filling site,the paper analyses the diseased foundation of Jiuzhou City residential district.It can be seen that there are great topographic differences in the building site before construction.After filling and excavating the filling site during construction and construction,uneven settlement or partial immersion subsidence of the foundation occur in the site,and subsidence or subsidence of all parts of the foundation.Various magnitudes cause additional stress and deformation in the superstructure.The reason is that the bottom of the original filling site fluctuates greatly,the thickness of the upper filling is large,uneven and has strong collapsibility.Affected by surface water seepage and pipeline rupture,the soil structure is destroyed,the strength decreases rapidly,and the foundation undergoes significant settlement deformation,which causes the cracking and inclination of the upper structure.(4)Taking a diseased foundation of Jiuzhou City residential district as an example,the numerical simulation is carried out.The self-weight,loading and local immersion are simulated,and the control group is set up to analyze the settlement and deformation law and stress.The results show that the settlement and deformation of the filling site can be greatly reduced by the foundation treatment.Different filling methods not only affect the settlement and deformation rate,but also affect the settlement and deformation rate.It also affects the stress distribution in the soil layer.After partial immersion,it can be seen that the filling undergoes large deformation in the foundation,which leads to the deformation of the pile foundation and raft at the bottom of the building,leading to cracking,inclination and subsidence of the building.(5)In view of the causes of foundation diseases in this district,relevant treatment measures are put forward for treatment,and then the foundation after reinforcement is simulated and analyzed by numerical simulation.The results show that the foundation after treatment is stable,the force of piles and rafts is uniform,the whole and part of the foundation is not deformed,and the foundation reinforcement measures are better.