黄土状粉土击实过程中土底压应力规律研究

Study on the Law of Bottom Pressure During the Compacting Process of Loessial Silt

通过系列室内击实试验,利用自主研发的土底压应力测试系统获得了土底压应力随击实作用时间、击实能、铺土层数、含水量的变化曲线,揭示了不同击实条件下土底压应力的发展规律。研究表明,土底压应力随击实作用时间的变化与土体的松密状态有直接关系。土体在击实过程中吸收击实锤冲击能量而变密实,提高了土体介质的传力效果。密实程度越大,传力介质越稳定,当达到相应条件下最大干密度时,土底压应力最大,作用时间最短。相同击实能条件下,土底压应力随铺土厚度增大而减小。当土体形成稳定传力介质后将不再吸收能量,土底压应力趋于稳定。含水量(质量分数)变化对击实能传递效果影响显著,最优含水量偏湿侧土底压应力出现陡降,土体传力效果降低。因此在击实过程中,要综合考虑上述因素对能量传递的影响。

The law of pressure transfer in soil during compaction reflects the effect of compaction energy.Through a series of laboratory compaction tests in door,the curves of soil bottom pressure changing with compaction time,compaction energy,number of soil layers and water content were obtained by using the independently developed soil bottom pressure testing system,so as to reveal the law of development of soil bottom pressure under different compaction conditions.The results show that the change of soil bottom pressure with compaction time directly relates to the state of soil’s loose ness or denseness.During compaction,soil absorbs the energy of compaction hammer and becomes densified,which improves the transmission effect of soil medium.The higher the compactness is,the more stable the medium is.When the soil reaches the maximum dry density under the corresponding conditions,the soil bottom pressure is the largest and the compaction time is the shortest.Under identical compaction energy,the bottom pressure decreases with the increase of layer thickness.When a stable medium is formed,the soil hardly absorbs energy anymore,and the bottom pressure tends to be unchanged.The water content has a significant influence on the compaction energy transfer effect,and the bottom pressure shows a steep drop,and the effect of compaction energy transfer is greatly reduced on the wet side of the optimal water content.Therefore,the influence of the above factors on energy transfer should be comprehensively considered in the compaction process.