Study On The Effect Of Single Point Impact Load On Red Sandstone Filling And Its Dynamic Consolidation

Red sandstone is widely distributed in our country, it is widely used to backfill foundation, the reinforcement effect of foundation under impact loading such as dynamic compaction is remarkable, but the research on red sandstone soil foundation treatment under impact loading such as dynamic compaction is relatively hysteretic. This paper aims at red sandstone soil, using compaction test equipment which is refitted to do laboratory compaction experiment, studying the effect of red sandstone soil under single-point impact loading; By means of having field dynamic compaction test to study the reinforcement effect of foundation, the main conclusions are as fallows:(1) The comprehensive reinforcement effects of dynamic compaction on red sandstone soil foundation are the push-pull effect of compression wave, dilatancy and contraction effect of shear wave and tumbling effect of rayleigh wave.(2) The growth range of cohesive force is much more faster than internal friction angle under impact loading; according to the space compaction effect of red sandstone soil, the soil under tamper hole is better than the soil around tamper hole, light hammer and high fall is better than heavy hammer and low fall.(3) The change law of accumulated settlement of tamper hole along with tamping numbers can be divided into faster and slower two phases under impact loading; the displacement under tamper hole is mainly the vertical displacement, the displacement around tamper hole is mainly the horizontal displacement; with the increase of single tamping energy (15、20、25、30N·m), the soil’s notable displacement action range change from3.0-3.5cm to6.0-6.5cm in horizontal direction and from9.0～10.0cm to18.0～19.0cm in vertical direction; with the improvement of system’s balance level, tamping energy which is used to improve system’s balance level is reduced, the utilization of tamping energy reduced, the system tend to a certain relatively stable equilibrium state according to the tamping energy, different tamping energy has different stable equilibrium state.(4) Base on the paper’s construction parameters, the reinforcement effect of dynamic compaction on dealing with red sandstone soil foundation is good, having met the design requirements of the project.The research results of the paper have a great significance on enriching foundation reinforcement theory of impact loading such as dynamic compaction, guiding the practice of foundation reinforcement under impact loading, improving the design level of foundation under impact loading.