Research on the static and dynamic characteristics of red clay anti-seepage soil materials in the design of core wall dams

Abstract

Red clay is widely distributed in the southern regions of China and is a unique regional soil type. Due to the complexity of its formation environment, the engineering geological properties of red clay are very special, making its practical application in engineering construction rather complex and difficult. Especially in the design of core wall dams for seepage prevention, there are few cases where red clay is used as the seepage prevention material for core wall dams, and there is a lack of scientific experimental theories for reference and guidance in this regard. Therefore, based on a certain reservoir project in the western part of Yunnan Province, this study conducted detailed physical property tests, consolidated undrained shear tests, static triaxial compression tests, and resonant column tests on the red clay used as the seepage prevention material for the core wall dam of this reservoir, to analyze the static and dynamic characteristics of this red clay material. The research result show that the gradation of the available red clay within the study area is uneven, with relatively large liquid limit, plastic limit, and plasticity index, and poor engineering properties. The test result indicate that when the stress is within a relatively large range, as the stress gradually increases, the shear strength of the red clay gradually decreases. If expressed by the Mohr strength envelope, it shows a downward-bending curve. At this time, when using linear strength indicators, there is usually a certain cohesion. When the consolidation ratio is constant, the larger the confining pressure, the slower the attenuation of the dynamic shear modulus ratio G/G_max with the increase of the dynamic shear strain amplitude γ, and at the same time, the smaller the damping ratio D under the dynamic shear strain amplitude γ.

Keywords

red clay / core wall dam / triaxial compression test / dynamic shear modulus / damping ratio