YAN R T, LIU S H, JI J U, et al.Study on the effect of biochar on the swelling force of Baise expansive soil [J]. Journal of Henan Polytechnic University( Natural Science) ， doi: 10.16186/j.cnki.1673-9787.2024120033.

doi: 10.16186/j.cnki.1673-9787.2024120033.

Received：2024-12-15

Revised： 2025-04-21

Online：2026-07-17

Study on the effect of biochar on the swelling force of Baise expansive soil (Online)

Yan Rongtao, Liu Sihao , Ji Jingru, Lin Cancan, Lin Deyou，Wang Guoyan，Yu Haihao

Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering, Guilin University of Technology,Guilin 541004 ,Guangxi,China

Abstract: Objectives To investigate the effect of incorporating biochar as an additive on the swelling characteristics of expansive soil. Methods Biochar is characterized by strong ion exchange capacity, large specific surface area, low density, high porosity, and excellent stability. By incorporating biochar (0%, 1%, 3%, 5%) into expansive soil and using the constant volume method, this study examined the influence of different biochar contents under varying initial water content and dry density conditions on the temporal variations curves of swelling pressure and the maximum swelling pressure of Baise expansive soil. Results The experimental results showed that the addition of biochar significantly altered the swelling characteristics of expansive soil. With an increase in biochar content, the maximum swelling pressure of the modified expansive soil increased, reaching a maximum increase of 130% at 5% biochar content. Furthermore, the magnitude of the increase varied across different dry density and initial water content conditions. The temporal variations curves of swelling pressure of expansive soil with biochar were similar in overall trend to those without biochar; however, as the biochar content increased, the duration of the accelerated swelling phase was prolonged, and the samples reached the maximum swelling pressure and slow swelling stage later. Additionally, with higher dry density, the maximum swelling pressure of the modified expansive soil also increased. However, the effect of initial water content on the maximum swelling pressure did not exhibit a simple linear relationship. Conclusions The influence of biochar on the swelling characteristics of Baise expansive soil has significant scientific and engineering value.

Key words: biochar; constant volume method; expansive soil; modification; temporal variations curves of swelling pressure