The Study On Prediction And Control Of Deformation Of Red-sandstone-subgrade

Red sandstone is widely distributed in the south of China which is used to fill subgrade in many expressway projects.However,the poor engineering of red sandstone characteristics such as low strength,high degree of weathering,softening and disintegration in water which are easy to cause subgrade settlement,pavement cracking and other diseases.Therefore,it is very important to study the deformation characteristics and settlement prediction of red sandstone subgrade for the design and construction of practical projects.Based on a national road project in Jiangxi Province,this paper studies the engineering characteristics and deformation characteristics of red sandstone subgrade filler by means of indoor test,finite element numerical simulation and fitting prediction.The main work is as follows:1.Carry out indoor geotechnical test,analyze the basic physical properties of red sandstone and CBR as subgrade filler.The results show that although the red sandstone has the characteristics of softening when encountering water and low strength,all indexes meet the relevant requirements of the code for design of highway subgrade,providing reliable basis for evaluating its road performance and establishing the finite element model of subgrade.2.Build a three-dimensional finite element model by using FLAC 3D software and simulate the deformation characteristics of red sandstone subgrade under different rainfall duration and rainfall intensity.At the same time,the influence of elastic modulus,cohesion and filling height of red sandstone subgrade on the deformation characteristics of red sandstone subgrade is studied.3.The settlement monitoring is carried out in three stages: filling stage,stabilization stage and later stage of construction.The rationality of the model is verified by comparing the simulation results with the measured data.At the same time,according to the analysis of settlement results,it can provide reference for the reserved height in the filling process of different road sections.The monitoring results show that the settlement distribution of the road section in these three stages is generally "large in the middle and small at both ends",and the horizontal displacement is increasing stably.4.Establish a Poisson index curve weighted combined prediction model based on Induced ordered weighted harmonic averaging operator(IOWHA),and carry out prediction analysis by combining the measured settlement data of typical sections.The results show that compared with the traditional Poisson curve and index curve prediction model,the Poisson index curve weighted combination prediction model based on the IOWHA operator has a better fitting effect.The combination prediction model has a certain reference value for the deformation and settlement prediction of red sandstone subgrade.