人工胶结砂物理力学特性试验研究

采用二次掺水法制备氧化钙胶结砂样，为加速碳酸化将试样放置在充满干冰的养护箱中养护，养护完成后对不同氧化钙掺入比的试样进行固结排水三轴试验和碳酸钙定量化学试验，分析了氧化钙掺入量对胶结砂物理力学特性的影响，定义了反映胶结物生成量的化学指标 ，利用 修正了摩尔-库仑强度理论。结果表明：二次掺水法可有效控制人工胶结砂的初始含水率，CaCO3胶结物的形成对试样物理力学特性有极大影响。在不同围压下，试样均表现出应力软化。随氧化钙掺入比的增加，试样应力软化现象逐渐增强，并且黏聚力及内摩擦角增量逐渐增大。胶结砂具有压硬性，围压、氧化钙的掺入比对试样剪胀有抑制作用。随着 的增加，试样黏聚力、摩擦角增量均有明显提高，通过试验数据得到了 与试样黏聚力、内摩擦角增量之间的函数关系，进而对摩尔-库仑强度理论进行了修正，修正后的公式能够反映胶结物的形成对胶结砂强度的影响。

Experimental study of physico-mechanical properties of artificially cemented sand

Cementation plays an important role in the stress-strain and strength behavior of cemented sand. The calcium oxide cemented sand samples prepares artificially in twice mixing water method. In order to speed up the carbonation reaction, samples are then placed in a humid room filled full of dry ice. Until samples curing are finished, consolidated drained triaxial tests and CaCO3 quantitative chemical tests are conducted on artificially cemented sand which have different cement ratios. The influence of cement ratio on the physico-mechanical characteristics of cemented sand is analyzed. Defined the product of CaCO3 content and Ca(OH)2 content as the chemical index to estimate the degree of cementation, an modification is given on Mohor-Coulomb strength theory using the chemical index . The test results show that twice mixing water method can effectively control the initial moisture content of artificially cemented sand; the formation of carbonate cements have a great influence on physico-mechanical properties of artificially cemented sand. At different confining pressures, samples show stress softening. With the increasing of cement ratio, stress softening are enhanced, cohesion and increment of frictional angle increase. Cemented sand has property of pressure sensitivity. Confining pressure and cement ratio can effectively control dilatancy. With the increasing of , cohesion and increment of frictional angle increase. The quantitative relations of cohesion, increment of frictional angle vs. are obtained. Combined with the test results, the relationship of shear strength parameter and is established to modify Mohr-Coulomb strength theory. This modified model can reflect the influence of carbonate cements on strength of cemented sand.