不同区域粉土累积塑性应变预测模型

Cumulative Plastic Strain Prediction Model for Silt in Different Regions

机场道基在长期服役过程中,不同区域粉土的累积塑性应变发展有显著差异。目前研究中鲜有考虑粉土区域性差异影响,尚未有预测模型能够对不同区域机场的道基粉土进行统一量化和预测。为确定影响粉土累积塑性应变的关键指标,有针对性地预测各区域粉土塑性应变,保证道基的长期服役性能,从华北地区3个不同机场取现场道基粉土,开展了不同区域和不同黏粒含量下粉土的动三轴试验,以揭示了不同条件下粉土累积塑性应变发展规律;通过SPSS灰色关联分析探究了不同区域粉土的矿物成分、颗粒级配、液塑限、最优含水率和最大干密度等指标与其循环荷载下最终累积应变的相关性,确定了黏粒含量为关键评价指标;基于试验结果建立了最终累积塑性应变预测模型。结果表明:不同区域粉土的颗粒级配、液塑限和最大干密度均有显著差异;循环荷载下累积塑性应变也差异显著,且受动应力影响;通过灰色关联分析,确定了以黏粒含量作为评价各地粉土最终累积塑性应变的量化指标;基于不同黏粒含量的动三轴试验结果,建立了考虑区域差异和动应力幅值的最终累积塑性应变预测模型。该预测模型能较好适用于不同区域机场道基粉土,基于当地粉土黏粒含量情况,较为准确地预测其长期服役过程中的累积塑限应变。

During the long-term service of airport subgrade,the development of cumulative plastic strain of silt in different regions is significantly different.The regional differences of silt are seldom considered in current studies.The current prediction models rarely quantify and predict the roadbed siltation uniformaly for different regional airports.To determine the key influence indicators affecting cumulative plastic strain of silt,predict the plastic strain of silt in different regions,and ensure the long-term service performance of subgrade,the study took soil from the silt subgrade of 3 different airports in North China.The dynamic triaxial tests of silt in different regions and with different clay contents were carried out,which revealed the development of cumulative plastic strain of silt in different conditions,and investigated the mineral composition of silt in different regions through the SPSS grey correlation analysis.Through SPSS grey correlation analysis,the correlation among mineral composition,grain composition,liquid-plastic limit,optimum water content,and maximum dry density of silt in different regions and the final cumulative strain under cyclic loading were investigated.The clay content was finally determined as the key evaluation indicator.The prediction model of final cumulative plastic strain was established on the basis of test results.The result indicates that there are significant differences in grain composition,liquid-plastic limit and maximum dry density of silt in different regions.The cumulative plastic strains under cyclic loading also differ significantly,and are affected by dynamic stresses.Through the grey correlation analysis,the viscous grain content is determined as the quantitative indicator for evaluating the final cumulative plastic strains of silt in different regions.Based on the result of dynamic triaxial tests with different clay contents,the prediction model of final cumulative plastic strain considering regional differences and amplitude of dynamic stress was established.The prediction model can be applied to different regions of airport subgrade silt.Based on the local silt clay content,it can accurately predict the cumulative plastic limit strain during long-term service.