不同碳酸钙含量黄土强度特性研究

Strength Characteristics of Loess with Different Calcium Carbonate Contents

通过对4种不同碳酸钙含量的黄土试样进行常规三轴试验,研究了黄土在不同初始含水率、不同围压、不同干密度下的强度特性,进而分析碳酸钙含量变化对土体强度特性的影响。结果表明:在不同干密度和含水率情况下,4种不同碳酸钙含量的黄土试样在不同围压水平下的应力—应变关系曲线均无峰值出现,属应变硬化型;在同一围压下,试样达到相同应变时,土样主应力差随着碳酸钙含量的减少而减小;黏聚力c和内摩擦角φ随含水率增大而减小,随着干密度的增大而增大;4种不同碳酸钙含量土样的黏聚力c和内摩擦角φ随含水率和干密度变化的趋势基本一致,说明碳酸钙含量的变化只是改变了抗剪强度指标的大小,并未对其变化特性产生影响;碳酸钙含量与黄土抗剪强度指标值的大小呈正相关关系,即碳酸钙含量越大强度指标值越大。

The strength characteristics of loess under different initial moisture content, .confining pressure and dry density was studied through con- ducting triaxial test for loess with different calcium carbonate contents, thereby analyzing the influence of calcium carbonate contents on strength characteristics of loess. The analytical results indicate that ： at different confining pressure level, there is not any peak among all the stress-strain curves belonging to four kinds of soil samples with different calcium carbonate contents, which demonstrates that these curves are classified into strain hardening; at the same confining pressure level, principal stress difference decreases with the decline of calcium carbonate contents; cohesion c and internal friction angle 〈p rise with the decline of moisture content and the increase of dry density ; cohesion c and internal friction angle ~ of four soil samples change with moisture content and dry density, but their variation trends are similar in spite of possessing different calcium carbon- ate contents, which indicates variation of calcium carbonate contents only change the value of shear strength parameters, instead of influencing their variation characteristics ; shear strength parameters of loess are positively correlated with calcium carbonate contents.