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山区机场高填方地基一般采用强夯施工填筑而成,其填料通常为土石混合料。其中碎石料往往由爆破开采得到,其形状不规则,而土料的加入使其密实特性与纯碎石料又有所不同。针对高填方地基的上述特点,该文对长条形碎石颗粒采用颗粒流软件PFC3D进行土石混合料地基的强夯模拟。为研究颗粒形状和细粒含量对强夯效果的影响,同时建立了椭球形颗粒模型和球形颗粒模型作为对比模型。首先研究了强夯冲击荷载作用下的重锤响应及地基内部动应力的分布和变化规律,并给出了强夯过程中的夯沉量和孔隙比的变化,采用孔隙比变化量表征强夯效果。其次对强夯前后地基土取样进行不同大主应力方向的三轴剪切实验模拟,对比强夯前后土体性质,并统计了三维组构参数来研究强夯后土体的横观各向同性性质。结果表明:长条形颗粒的土石混合料强夯密实效果最显著;长条形碎石地基经强夯后呈现明显的横观各向同性性质,竖直方向较水平方向模量及峰值强度明显要大,而采用球形颗粒时土体保持各向同性。该文可对进一步研究强夯下高填方填料的横观各向同性本构模型提供有益的参考。
The high-filled foundation of mountain airport is generally filled with strong-rammer construction, and the filler is usually earth-rock mixture. Among them, the crushed stone is often obtained by blasting and mining, and its shape is irregular. However, the addition of soil material makes its compactness different from that of pure gravel. In view of the above characteristics of high fill foundation, this article uses the granular flow software PFC3D to carry out the dynamic compaction simulation of the soil-rock mixture foundation. In order to study the effect of particle shape and fine particle content on dynamic compaction, ellipsoid particle model and spherical particle model were established as the contrast model. Firstly, the distribution of heavy hammer response and the dynamic stress distribution and the change rule of dynamic stress under dynamic impact loading are studied. The changes of dynamic compaction and void ratio during dynamic compaction are given. The variation of void ratio is used to characterize dynamic compaction effect. Secondly, the triaxial shear tests of soil samples before and after dynamic compaction were carried out for different directions of principal stress. The soil properties before and after dynamic compaction were compared and the three-dimensional structural parameters were calculated to study the transversely isotropic nature. The results show that the compacting and compacting effect of soil-stone mixture with strip-shaped particles is the most obvious. After the dynamic compaction, the strip-shaped macadam base shows obvious transverse isotropy, and the horizontal modulus and peak intensity in vertical direction are obviously To be large, and the use of spherical particles soil to maintain isotropy. This article can provide a useful reference for further research on the transverse isotropic constitutive model of high fill under dynamic compaction.