Research On The Relationship Between The Subgrade Soil Dynamic Characteristics And Compaction

Subgrade compaction is a crucial process in highway engineering,and the degree of subgrade soil compaction directly affects the design life of the highway.The compaction process of subgrade soil is not only the change of soil compaction degree,but also the change of soil dynamic characteristics.To understand the dynamic characteristics of different compacted soils,and to propose a more reliable and effective compaction index is the development direction of compaction detection technology.Therefore,it is very necessary to study the relationship between the dynamic characteristics of subgrade soil and the degree of compaction.In this paper,the subgrade filling of a certain ground in Xuzhou is taken as the object.The vibration acceleration signal of the soil is obtained through the hammer hammer test.At the same time,the compaction degree of the soil is measured.Based on the wavelet analysis,the vibration acceleration signal of the soil is analyzed and processed.The relationship between the dynamic index of soil and the degree of compaction.The main research contents are as follows:First,a heavy hammer hammer test was carried out on the test soil samples with a certain degree of compaction in the laboratory,and the force and acceleration signals under the hammer hammer were obtained.Secondly,based on the wavelet threshold denoising method,152 digital filters are designed to denoise the acceleration signal and evaluate the effect.The research results show that: the digital filter using db5 wavelet basis function,4-layer decomposition,unbiased likelihood threshold value estimation and hard threshold value function is the optimal denoising combination for the denoising of the test soil vibration signal.Then,the vibration acceleration signal of soil is analyzed from two angles of time domain and frequency domain,and the time-domain characteristic parameters of the signal: peak-to-peak value and effective value;the frequency-domain characteristic parameters of the signal: frequency domain curve and frequency axis The ratio A/L of the surrounding area A to the frequency distribution interval L.In addition,based on the wavelet packet analysis and the singular value decomposition method,the soil vibration signal is described and extracted from the energy point of view,and energy characteristic parameters that can characterize the soil dynamic characteristics are proposed: k1,k2,and k3.Finally,the correlation between the above-mentioned characteristic parameters that characterize the dynamic characteristics of the soil and the degree of compaction are analyzed.The results show that:(1)The peak-to-peak value and effective value of the acceleration signal increase with the increase of compaction;(2)The A/L value of the acceleration signal decreases with the increase of compaction;(3)The acceleration signal The k1 and k3 values showed a decreasing trend with the increase of compaction degree,while the k2 value of the acceleration signal showed an increasing trend with the increase of compaction degree.The empirical function relationship between each parameter and the degree of compaction is also given.This paper has 67 pictures,14 tables,and 81 references.