珊瑚颗粒形状对钙质粗粒土的压缩性能影响

INFLUENCE OF CORAL SAND PARTICLE SHAPE ON THE COMPRESSION PROPERTY OF COARSE GRAINED CALCAREOUS SOIL

珊瑚颗粒形状不规则是其显著区别于陆源土的一大特征。为揭示珊瑚颗粒形状对钙质粗粒土压缩性能的影响,人工挑选出不同形状(块状、枝状、棒状、片状)的珊瑚颗粒,以块状颗粒为基础,与其他3种不同形状的粗颗粒任意一种混合,控制不同颗粒形状配比制成钙质粗粒土试样,完成室内压缩试验,对比分析试验前后珊瑚颗粒的圆度、长宽比、扁平度和凹凸度等形状参数,评价颗粒形状对压缩性能的影响。结果表明:(1)粒径为10~20 mm钙质粗粒土的压缩模量是4~5. 5 MPa,回弹系数为42~53;(2)随枝状、棒状或片状颗粒掺量的增加(0、10%、20%、30%),试样压缩模量呈小幅波状变化,回弹系数呈持续减小趋势;(3)各加载区间应力-应变曲线包括应力快速增长阶段、应力-应变同步增长阶段、应变增长阶段共3个阶段和1个稳定点;(4)随枝状颗粒掺量的增加,试样的长宽比和凹凸度逐渐增加,圆度和扁平度基本无变化;因颗粒破碎的影响,试验后试样的长宽比及扁平度有所增加,圆度及凹凸度则有所减小。选择钙质粗粒土地基时,应考虑其压缩性能,避免施工初期的快速加载。

The irregular shape of coral sand particles is a major feature that distinguishes it significantly from the ordinary terrigenous soil. In order to research the influence of coral sand particle shape on the compression property of coarse grained calcareous soil,different coral sand particles( block,branch,rod,flake) were selected manually.Based on the block particles,mixed with any of the other three different shapes of coral sand particles,the different particle shape ratios were controlled to make coarse grained calcareous soil samples,and the indoor compression tests were complete. The particle shape parameters such as roundness,length-width ratio,flatness and convexity of coral sand particles before and after the test were compared and analyzed. The effects of particle shape on the compressibility were evaluated. The test results show that:(1) The compression modulus of coarse grained calcareous soil with diameters of 10 ~ 20 mm is from 4 to 5. 5 MPa,and the rebound coefficient is from 42 to 53;(2) With the increase of the amount of branch,rod or flake particles(0,10%,20%,30%),the compressive modulus of the sample changed slightly,and the rebound coefficient continued to decrease.(3) The stress-strain curves of each loading range include one stable point and three sections which are rapid growth stress section,synchronous increase of stress and strain section,strain growth section;(4) With the increase of the amount of branch particles,the length-width ratio and the convexity of the sample increased gradually,while the roundness and flatness were unchanged substantially. Due to the influence of particle breakage,the length-width ratio and flatness of the sample increased after the test,while the roundness and concavity decreased. When selecting coarse grained calcareous soil foundation,its compressibility should be considered to avoid rapid loading at the beginning of construction.