| In the process of road construction,the quality of roadbed compaction is the key to long-term and effective operation of roads.And the current road construction mainly depends on the engineering personnel to control the compacting process of the roller.Due to the limitations of human ability,leakage pressure,under pressure,overpressure and so on,the quality of subgrade compaction can`t reach the standard.In addition,the current compaction quality detection of soil subgrade is mainly through the way of digging holes,using the test results of limited detection points to judge the compaction quality of the whole construction section.It is easy to form deviations and can`t represent the compaction quality of the whole section.At the same time,this kind of method has a certain lag,and to some extent,it will cause damage and damage to the roadbed.Therefore,a set of nondestructive testing method that can real-time feedback the compaction quality of soil roadbed is developed,which has certain engineering significance for compaction construction of roadbed.This paper mainly relies on the construction project of the Beijing Qin expressway,and carries out the research on the automatic continuous detection technology of the compaction degree of subgrade soil.The main work and research results are as follows:(1)Firstly,a variety of methods to detect the compaction degree of the foundation soil are summarized,and the different methods are introduced in the actual operation process,and the characteristics and shortcomings of each method in the degree of compaction test are emphatically analyzed.(2)Secondly,starting from the working mode of the roller of the roller,the mechanism of the compaction of the vibrator is studied according to the principle that the centrifugal force will produce the wheel vibration according to the high speed rotation of the eccentric axis in the vibration wheel.The mathematical model and dynamic equation of the vibration wheel-disturbed soil are established.The relationship between the degree of compaction and the stiffness of subgrade soil is positively correlated and the damping coefficient is negatively correlated.The vertical acceleration on the subgrade soil stiffness is positively correlated with the soil stiffness of the subgrade,and the damping coefficient is negative by the simulation of Matlab modeling.Furthermore,the change of vibration acceleration value can reflect the compaction degree of subgrade soil.(3)A large number of indoor soil tests were carried out on the roadbed soil of the test section,and the different engineering characteristics of subgrade soil in each test section were analyzed.The automatic continuous testing of the degree of compaction of the 3 different test sections was carried out respectively.The vibration acceleration increased with the increase of the number of compaction at the same point,and the number of compaction was positively correlated with the vibration acceleration.Under the same compaction times,the acceleration basically has little uniform deviation,but the average vibration acceleration of silty soil and sandy soil subgrade is larger than that of gravel soil subgrade under the same compaction times.The reasons for the above phenomena are analyzed and summarized.(4)Finally,based on the results of the automatic continuous test of compaction degree,the automatic continuous testing compaction degree model under different compaction times and the automatic continuous detection of compactness model under different soil conditions are established by spss22.0.This will provide reliable basis for the automatic continuous detection of the compaction degree of the soil subgrade. |
