Research On Subgrade Performance Prediction Of Building Waste Backfill Vehicle Depot Based On Multiple Regression Analysis

With the rapid development of urban subway construction,the number of parking lots（rolling stock depot）is also increasing.The construction of a lot of several hundred mu will lead to the demolition of a large area of buildings,which will naturally produce a lot of solid waste.It is not only a huge waste of resources,but also adversely affects national carbon emission targets.In order to solve the above problems,this paper relies on the rolling stock depot project of Zhengzhou Metro Line 12 to study the construction waste in Zhengzhou,aiming to realize the recycling of construction waste at the generation site,so as to realize energy conservation and emission reduction in the construction industry.In this study,laboratory test and field test were combined to carry out compaction test,CBR test,compactness test,K₃₀ test and plate load test in turn.The test results all show that the recycled construction waste material has excellent road performance.Due to the great difference in the performance of different components of construction waste,it is difficult to control the bearing capacity of the material in the actual backfill.Therefore,this study established a recycled material prediction model based on a large number of tests and ABAQUS numerical simulation.This model can predict the CBR value of recycled material,the bearing capacity characteristic value of recycled material after backfilling,and the applicable range of various materials according to the composition of construction waste material on site.At the same time,this model can quickly and accurately obtain the bearing property parameters of recycled materials by analyzing the physical and mechanical parameters of raw waste materials,and further judge its application scope.The prediction model can greatly reduce the difficulty of application of construction waste recycled material in subgrade backfill.The main contents of this study are as follows:（1）This paper takes typical construction waste（concrete block,brick and gravel）in Zhengzhou as the research object and subgrade backfill as the main research and application direction.By dividing recycled materials into fine,medium and coarse groups according to particle size composition,and conducting compaction test,screening test and CBR test successively,relevant characteristic indexes of different groups of materials applied to backfill areas with different strength requirements are obtained.The reuse of construction waste materials is realized to the greatest extent.（2）According to the research,the bearing capacity of construction waste recycled material is mainly determined by the material particle size composition,brick proportion,water content and compaction times.On the basis of analyzing the influence law of each factor acting alone,this study focuses on analyzing the variation law of bearing performance under the synergistic action of multiple factors.In this section,orthogonal test method is used to design the test scheme,and multiple regression analysis method is used to propose the prediction formula of CBR value.The prediction effect of this formula is accurate,and it can predict the recycled material CBR strength quickly and accurately before construction,so as to effectively guide the field construction.（3）This paper tests whether the bearing capacity of recycled material can meet the requirements of site filling by laying test section.The test section is divided into three sections.The first section,the second section and the third section respectively use the recycled material with different CBR strengths.By controlling the field construction conditions and the laboratory test standard of reprinting,and using the compactness to check the backfilling effect of the test section,the optimal virtual thickness and the optimal number of rolling passes of different test materials are finally determined.After the test section was laid,this study tested the bearing capacity of each subgrade through K30 test,heavy dynamic penetration test and flat plate load test,and determined the applicable scope of recycled materials used in each section according to the different bearing capacity.Based on the above performance testing tests,this study proposed a set of recycled material application prediction model,which is composed of field materials to predict CBR strength,then predict backfill bearing capacity and determine the applicable area of materials,so as to provide a fast and accurate strength prediction method for recycled material backfill subgrade.（4）In this study,the finite element software ABAQUS was used to simulate the slab load test in the test section to analyze the relationship between the simulated settlement and the measured settlement,and an empirical formula was proposed to predict the measured settlement based on the simulated settlement,realizing the rapid and effective prediction of the characteristic value of the bearing capacity of the recycled backfilled subgrade without the slab load test,and improving the accuracy of the recycled material prediction model.