Experimental And Numerical Study On The Vibration Impact Of MHB Rubblization On Adjacent Structures

Recently, rubblization has been widely used in the old cement concrete pavement reconstruction project because it can prevent reflection cracks effectively, save resources and reduce the cost of road restoration. However, crushing machinery contains huge impact energy that will produce vibration or even destruct the buildings along the route during construction. Therefore, one of the difficult points is how to judge the impact area and degree of rubblizing construction to avoid the adverse effects on environment.The propagation characteristics and attenuation variation of vibration wave were studied caused by shock based on the theory of vibration wave. The security buried depth of pipe culvert was put forward through the calculation of the vibration load capacity of buried pipe culvert. Vibration impact of adjacent buildings, buried pipelines and slope were analyzed. Then control standards and safeguards of nearby structure were proposed depended on reconstruction project of provincial road 245 in Shandong Province. Vibration positions and impact energy influence to fragmentation level of old cement concrete pavement were discussed by ANSYS/LS-DYNA program.The dynamic response of buried pipeline under shock load was analyzed in cases of vibration positions, impact energy, horizontal spacing and buried depth, which would help to guide MHB rubblizing construction. The main conclusions are as follows:(1) The impact and vibratory response of rubblizing construction has a transient vibration characteristics. It is a kind of low frequency and high amplitude vibration and has essential difference from the continuous forced vibration under earthquakes.Vibration response attenuation has the same laws in different strokes, and the vertical vibration occurs more commonly near the source of vibration.(2) Vibration of rubblization construction will affect the safety of nearby buildings and the comfort of the residents. By calculating the critical safe distance of adjacent buildings are 14 m, 18 m and 20 m respectively and the distance of without affecting residents are 24 m, 29 m and 31 m as the hammer drop height are 0.8m, 1.0m and 1.2m. The safety depth of the buried concrete pipelines is 2.4m and the safety horizontal distance of the building on the embankment slope is 12 m as the stroke is1.0m.(3) The hammering position has a strong influence on vibration of pavement structure. The influence is more obviously and the pavement is the easiest breakingwhere the position is at plate corner. So, the first step of construction is to rubble slab corner and gradually to move the central. In the four affecting factors on vibration velocity of pipe culvert, horizontal distance is the highest of parameter sensitivity,buried depth, loading position and stroke following. The methods of avoiding,reducing frequency and stroke are adopted to reduce the vibration influence on adjacent structures during construction.