膨胀土膨胀性及强度特性分析

Expansion and Strength Characterization of Expansive Soils

摘要: 本文所用土壤取自南水北调中线工程邓州段，通过自由膨胀率试验得出所用的膨胀土为弱膨胀土，其有荷膨胀率随时间的增长先快速增大后趋于稳定，随荷载的增大不断减小；在无侧限抗压试验中，九种含水率下土体的应力应变曲线均为软化型，其应力应变曲线可以分为弹性阶段–裂纹稳定扩展阶段–裂纹快速扩展阶段–和裂纹完全贯通阶段；膨胀土的无侧限抗压强度随含水率的增大不断下降；在直接剪切试验中以18%含水率为分界线，含水率小于18%时应力应变曲线为软化型，含水率大于18%时为硬化型，抗剪强度随含水率增大先增大后减小，粘聚力随含水率的变化规律也是随含水率的增大先增大后减小，内摩擦角则是随含水率的增大不断减小。

Abstract: The soil used in this paper is taken from the Dengzhou section of the South-to-North Water Diversion Project, and the expansion soil used is a weakly expanding soil through the free expansion rate test, and its loaded expansion rate increases rapidly with time and then tends to stabilize, and then decreases with the increase of load; in the unconfined compression test, the stress-strain curves of the soil body under the nine water contents are all of the soft type, and the stress-strain curves can be divided into elasticity stages Stable crack expansion stage-Rapid crack expansion stage—and complete crack penetration stage; The unconfined compressive strength of expansive soil decreases with the increase of water content; In the direct shear test, 18% water content is used as the dividing line, and the stress-strain curves are of softening type when the water content is less than 18%, and the stress-strain curves are of softening type when the water content is greater than 18%. In direct shear test, the stress-strain curve is softening type when the water content is less than 18%, and hardening type when the water content is more than 18%, the shear strength increases and then decreases with the increase of water content, the change rule of cohesion with the increase of water content also increases and then decreases, and the angle of internal friction is decreasing with the increase of water content.