Analysis Of Interaction Between Road Vibration Construction And Abutment Pit Construction On Silt Soil

Foundation pit engineering has been the most difficult problem in the field of geotechnical engineering.Among them,we attach more importance to the mutual influence analysis of the adjacent construction of cross-engineering.For one thing,the foundation pit construction will damage the surrounding roads and underground pipelines;for another,when the road around the foundation pit is under construction,heavy rollers and other vibration will impact the foundation pit project.In view of these problems,comprehensive research on soil loading and unloading deformation theory,this paper uses PLAXIS to make a complex model of road foundation pit with moving vibration load at first based on the actual project of Hangzhou Jiuheng Road and 02,03 plots..PLAXIS combined with ABAQUS numerical simulation and engineering monitoring are carried out by adopting method of a combination of numerical simulation and construction monitoring.The studies are as follows:1.In theory.The recommended values of HSS model parameters were concluded through literature review combined with laboratory tests based on the summary of previous studies.The elastic modulus of asphalt mixture with temperature and the corresponding fitting equation were determined by laboratory tests.The indirect tensile strength of cement stabilized macadam at different ages and the change rule of compressive modulus of cement stabilized macadam with time were determined,and the structural parameters of pavement material were determined.By comparing the advantages and disadvantages of different damping theory.Rayleigh damping was selected in this paper to provide a theoretical basis for the PLAXIS and ABAQUS numerical simulation.2.In the aspect of the impact of excavation on the road.With the help of PLAXIS 3D finite element platform,a composite model of roadbed with subgrade and subgrade is established to simulate the whole process of the interaction of foundation pit with road construction.The results show that:the influence range of soil behind the wall is greater than 3H(H is the depth of excavation),and uneven settlement occurs on the roads within 3H.The maximum settlement of the road occurred at the distance from excavation site was H/2.which was consistent with the monitoring data.The tensile stress of the cement stabilized grassroots during excavation to the bottom of the pit was mainly between 0.24MPa and 0.28MPa.When considering the reduction of grassroots strength and the vehicle load,the water-based grass-roots level may also reach its tensile strength and thus produce cracking.3.With the help of combining the 3D modeling and 2D modeling by PLAXIS and ABAQUS finite element platform,the composite model of road foundation pit with moving load is established,and the influence of road construction on existing foundation pit is analyzed.The whole process of the influence of the existing foundation pit and pit buildings during construction is simulated,and the vibration response of the foundation pit maintenance structure,pit bottom soil and floor slab using common rock bolts and recoverable anchors and excavation conditions is obtained.The results show that different frequencies have little effect on the vibration velocity of surrounding buildings due to the high frequency of roller;the maximum principal stress of slab under vibration load is 0.346MPa,which is far less than the tensile strength of concrete;the construction of negative second floor slab is completed.The roadbed slag layer is vibrated and crushed,and the vibration load has the greatest impact on the buildings in the foundation pit.The vibration velocity at the horizontal direction is 0.32 cm/s and meets the specifications.4.Project monitoring.02,03 plots project on Jiuheng Road was monitored strictly according to the requirements of the standard.The main contents of monitoring include:deep soil displacement,horizontal displacement at the top of the slope,settlement of the top of the slope,settlement of the road around the foundation pit,settlement of the column,vibration speed of the floor and groundwater level etc.All of the monitoring results meet the requirements of the code,and the results of the monitoring and the numerical simulation have little difference and regularity,which shows that the simulation results are reasonable and reliable.It can be seen from the above research that in the process of cross-excavation of foundation pit and road adjacent engineering,if the road construction is carried out first and then the foundation pit construction,the road will be damaged;on the contrary,if the foundation pit construction,then the road construction,road vibration construction has little effect.If there is a foundation pit and road adjacent engineering,it is recommended to carry out foundation pit construction first.The results of this paper can provide some theoretical support for the similar construction of the adjacent construction.