高应力作用下钙质砂压缩及颗粒破碎特性试验研究

钙质砂是我国南海岛礁建设的主要材料,因其特殊的生物成因和独特的颗粒结构,其工程力学特性与常见陆源砂有较大差异。通过自行设计的高强加载压力室在三轴固液耦合试验机下对钙质砂进行终止应力在2~100 MPa间的侧限压缩试验,研究了钙质砂在高应力水平下的压缩和颗粒破碎特性,并通过相同试验工况下的石英砂单向压缩试验来进行对比研究。试验结果表明:在高应力作用下,钙质砂比石英砂的压缩变形量大,钙质砂的压缩屈服应力在2 MPa左右,远小于石英砂。钙质砂和石英砂在高应力作用下均会产生明显颗粒破碎,但钙质砂在应力作用下先于石英砂产生颗粒破碎。通过对颗粒破碎进行量化分析发现,两种砂样的颗粒破碎程度均先随应力的增大而增大,随后出现趋于稳定的趋势。

Compression and Particle Breakage Features of Calcareous Sand under High Stress

Calcareous sand is the main material for construction in the islets of the South China Sea. Because of its special biological origin and unique granular structure, its engineering mechanics characteristics are different from those of common terrigenous sand. A series of one-dimensional compression tests with final stress changed from 2 up to 100 MPa were conducted on calcareous sand to study its compression and breakage characteristics. These tests were carried out with triaxial solid-liquid coupling testing machine. The pressure chamber was made of high strength steel in this experiment to avoid test error caused by deformation of steel mold. And parallel uniaxial compression tests were carried out on quartz sand for comparative study with the same test conditions. The results show that the compression deformation of calcareous sand was larger than quartz sand and the yield stress of calcareous sand, which was about 2MPa, was less than quartz sand. During the test, significant particle breakage was found both in calcareous sand and quartz sand. However, particle crushing of calcareous samples happened earlier than quartz sand. It was found that the degree of particle breakage of the two sand samples increases at first with the increase of load stress, and then tend to be stable, through a quantitative analysis on particle breakage.