Study On The Application Of Automatic Continuous Compactness Detection Technology In Silty Soil Subgrade

Compaction operation is the key process to ensure the quality of highway construction and affect the service life of highway.The effective detection method is an important means to ensure the quality of compaction.Compared with the traditional detection method of subgrade compactness,the automatic continuous compactness detection technology has the characteristics of rapidity,timeliness and non-destructive,which effectively makes up for the shortcomings of the traditional detection method.It not only improves the detection accuracy,but also reduces the human intervention,reduces the possibility of detection data falsification,which is of great significance to ensure the compaction quality of highway subgrade.In order to verify the feasibility of this technology in the detection of the compaction degree of silty soil subgrade,this paper,relying on the connection line project of Langfang Beisan county section of the MI Zhuo expressway,carries out the research on the application of the automatic and continuous detection technology of the compaction degree in the Silty Subgrade Soil.The main work and research results are as follows:1)combined with the physical and mechanical characteristics of silt,the main reasons for the difficulty of compaction of silt subgrade are analyzed,and the influencing factors and improvement methods in the process of compaction of silt subgrade are studied.Based on the two degree of freedom mathematical model of "vibrating wheel disturbed soil" and the dynamic balance equation,the conclusion that the vertical vibration acceleration of roller is directly related to the rigidity and damping of subgrade soil is obtained by studying the mechanism of vibration compaction of silty soil subgrade.The result shows that the vertical vibration acceleration is directly proportional to the rigidity and inversely proportional to the damping.This law can be used to reflect the compaction of subgrade soil The compaction status in the process of compaction provides a theoretical basis for the automatic continuous compaction detection technology.2)the two degree of freedom mathematical model of "vibratory wheel disturbed soil" is simulated by MATLAB simulation software,and the three-dimensional simulation diagram of roller vibration acceleration and subgrade soil stiffness(damping)changing with vibration time is obtained.Through the analysis of the simulation results, the feasibility of the two degree of freedom mathematical model and the correctness of the derivation conclusion of the dynamic balance equation are verified,that is,it is feasible to express the degree of compaction of subgrade soil by the vertical vibration acceleration of the roller,which further consolidates the theoretical basis of this paper.3)the laboratory test of subgrade soil,the field collection test of acceleration signal and the correlation test of sand filling method are carried out for Dachang silt,Xianghe silt and Sanhe silt used in the project.According to the test results,the relationship between the effective value of the vertical vibration acceleration of the roller and the compactness of three kinds of silt subgrade is analyzed,and the model relationships are established respectively.Combined with the analysis results of three kinds of silt fine particle content,the influence rule of fine particle content on the model formula of silt compactness and effective value of vertical acceleration of vibrating wheel is obtained,and the relationship of automatic continuous compactness detection model for silt subgrade is established,which provides a theoretical basis for the application of this technology in silt subgrade.The test results show that the correlation between the effective value of the vertical vibration acceleration of the roller collected through the field test and the compaction degree of the silt subgrade detected by the sand filling method is high,so the automatic continuous compaction technology has better engineering practicability in the application of the silt subgrade.