压实黄土强度的三轴试验研究

Triaxial Testing of the Compacted Loess Strength

采用三轴试验研究不同含水率和不同压实系数条件下压实黄土的应力应变特性,获得了工程上常用的邓肯—张模型参数。结果表明:不同初始条件下主应力差-轴向应变关系基本符合双曲线关系;主应力差和初始切线模量随围压的增加而增大;对相同围压,破坏点处的主应力差随含水率的增大而减小,随压实系数的增大而增大;黏聚力、内摩擦角、K值及Rf随含水率的增加而减小,随压实系数的增加而增大;而n值的变化趋势刚好相反。

Strain-controlled triaxial unconsolidated and undrained shear tests were used to study the strength of compacted loess from the Qinghai region. The tests were conducted at moisture contents of 14% and 17% at 97% compaction,and 95% and 96% compaction at moisture content of 17%. The specimen diameter was 3. 91 cm,and the height was 8 cm. To analyze the stress- strain behavior, the Duncan-Chang model was used. The test results suggest that the deviator stress increases as the axial strain increases at different confining pressures regardless of initial moisture and compaction. The relationship between deviator stress and axial strain is close to hy- perbolic. The deviator stress and the initial tangent modulus increase as the confining pressure in- creases. At constant confining pressure, the deviator stress at failure decreases with increasing moisture and increases with increasing compaction. With increasing moisture content, the cohesion, friction angle, K, and Rf decrease, whereas porosity n increases. With increasing compaction, the cohesion, friction angle, K, and Rj increase, whereas n decreases.