Experimental Study On Circular Pile-well Blasting Effect In Limestone Formation

The country are accelerating infrastructure construction with the implementation of the country's western development strategy. The pile-well blasting technology is commonly used in foundation excavation of construction engineering in mountainous areas in south-west China, and the circular pile-well is currently the most widely used type of pile. However, blasting design and construction experience are generally in accordance with the given parameters. In order to achieve the better effect of blasting blindly increasing the explosive charge in per hole in the construction process. So the pile-well concrete lining often damaged, and even the security incidents have occurred such as collapsed and buried workers. It affects the construction schedule and threatens personnel safety. Therefore, Determine the main factors influencing pile-wells blasting effect and explore the relationship between the main factors and blast effects are very necessary. Thereby improving hole utilization ratio of pile-wells blasting and reduce the concrete lining damage.The paper used AHP draw the main factors influencing pile-walls blasting effect which are rock property, explosives consumption, geological structure, undercutting manner, the cross section size. The main three influential factors after the site selected for the explosive consumption, the cross section size, undercutting manner. Based on a Guiyang resettlement housing pile-well blasting engineering conducted a field experiment. 0.9m, 1.2m and 1.5m were selected as the test object well diameter pile statistics of different explosives consumption, undercutting manner, and calculated hole utilization ratio. Using TC-4850 N blasting vibration tester and DH3820 static strain test systems for concrete lining blasting vibration monitoring and strain monitoring respectively. Regression analysis according to Sadaovsky empirical formula were using. Attenuation formula of seismic wave propagation in pile shaft blasting excavation was got. The blasting vibration propagation and concrete lining axial, circumferential strain combined by field experiment monitoring data analysis,the relationship between the main factors and the utilization of blast holes was summarized, as well as the law of concrete lining strain and blasting vibration.Obtained the explosives consumption threshold of diameter 0.9m, 1.2m, 1.5m pile-wells explosives consumption, and empirical formula of the maximal segment charge and blast center distance to concrete lining. According to the experience formula of concrete lining and pile-well excavation of the minimum distance. It provided evidence for pile-well blasting design and construction.