Research On Continuous Compaction Mechanism Based On Stress Wave Theory

Continuous compaction control technology has been available for decades,its scientific and practical value has been confirmed in many domestic and foreign tests and practices,continuous compaction control technology has developed a number of continuous compaction indicators based on different algorithms for The management and discrimination of roller compaction construction quality has greatly improved the management and quality control of roller compaction construction.The previous continuous compaction theory is based on the "vibratory roller-soil" model.In this paper,the continuous compaction technology is studied and analyzed in combination with the vibratory compaction technology,domestic and international theories,algorithms and characteristics of various continuous and continuous compaction indexes,and domestic and foreign experimental phenomena.The mechanism currently used in continuous compaction technology still has many limitations,which is not conducive to the application and development of continuous compaction technology.By studying the propagation characteristics of stress waves in soil,this paper establishes a continuous compaction stress wave model based on the one-dimensional stress wave theory: the vibration wheel passes through its own vibration and the foundation of the soil layer and propagates to the soil layer.A stress pulse consisting of an amplitude stress wave.When the stress wave amplitude is greater than the soil yield limit,the stress wave is plastic wave propagation in the soil,and the plastic deformation of the soil is compacted;when the stress wave amplitude is less than the yield limit of the soil,it is an elastic wave.The elastic wave is reflected in the compaction layer and the underlying layer,and the reflected wave is reflected to the contact surface between the vibration wheel and the soil,changing the vibration shape and force state of the vibration wheel,and producing a continuous compaction value.In this paper,a laboratory vibratory compaction test was performed with the packing used in the project.The phenomenon of acceleration and spectrum change of the vibrator during the test verified the continuous compaction stress wave model: First,the maximum amplitude and acceleration of the sub-harmonics in the vibratory compaction process have increased—reduced cycle change,and the largest in the cycle change.The value decreases gradually,which accords with the change of the stress wave interference phenomenon;second,the dispersion of the stress wave appears at the crest during the acceleration change of the vibrator;thirdly,the compaction of the soil surface after completion of the vibratory compaction occurs,and the surface of the compacted construction appears loose.The phenomenon is different,and it conforms to the law of reflection of stress waves at different interfaces.Finally,the finite element numerical simulation and analysis of the vibratory compaction process and the Evd dynamic modulus detection process are performed using LSDYNA software.Both the vibratory compaction process and the Evd detection process show that the stress and strain in the soil model are based on wave propagation.The morphology spreads to all directions and depths;the soil stress changes along the depth in turn;by fitting the stress amplitude of the soil below the center of the vibrating wheel,it is found that the stress amplitude exhibits an exponential decay along with the depth change.These phenomena further reflect the mechanism of stress waves acting on the soil during continuous compaction.