摘要：
To enhance the improvement effect of Enzyme-Induced Carbonate Precipitation (EICP) technology more effectively, an abundant renewable resource-lignin-was introduced as an additive during the EICP modification process of silty clay. The mechanical properties of the improved soil specimens were analyzed from a macroscopic point of view by using unconsolidated undrained (UU) triaxial tests and unconfined compressive strength (UCS) tests to determine the optimal lignin content and curing time. The micro-mechanism of the improved soil specimens was elucidated from the microscopic point of view by combining scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. The experimental results showed that lignin synergized with EICP could effectively improve the mechanical properties of the soil, and the mechanical properties of the co-consolidated soil specimens were better than those of the single consolidated and untreated soil specimens as a whole. The single EICP-consolidated soil specimen had undergone brittle damage; lignin could enhance the toughness of the soil and weaken its brittle characteristics. With the increase of lignin content, the mechanical indicators of co-consolidated soil specimens showed the trend of increasing and then decreasing, and reached the optimum at 0.75%. Moreover, the addition of lignin significantly increased the cohesive force, while the friction angle was less affected. With extended curing time, the mechanical indicators of the co-consolidated soil specimens increased overall, and tended to stabilize after 7 days of curing, hence selecting 7 days as the optimal curing time. From the microscopic point of view, lignin provides nucleation sites for the calcium carbonate precipitates generated by EICP, and the joint action of the two can fill the soil pores and cement the soil particles, thereby improving the overall strength of the soil. The results of the study can provide a theoretical basis and practical reference for the construction of foundation projects in silty clay areas.
作者机构：
[Chang, Rui; Chen, Wenzhao] Univ South China, Sch Civil Engn, Hengyang 421001, Peoples R China.;[Liu, XQ; Liu, Xiqi; Chang, Yan] Pearl River Water Resources Res Inst, Guangzhou 510611, Peoples R China.;[Liu, XQ; Liu, Xiqi; Chang, Yan] Minist Water Resources, Res Ctr Pearl River Estuary & Coast, Guangzhou 510611, Peoples R China.;[Wang, Zhenhua; Zhang, Fuqing] East China Univ Technol, Sch Civil & Architecture Engn, Nanchang 330013, Peoples R China.;[Li, Dongwei] Dalian Univ, Coll Civil Engn & Architecture, Dalian 116622, Peoples R China.
通讯机构：
[Liu, XQ ] P;Pearl River Water Resources Res Inst, Guangzhou 510611, Peoples R China.;Minist Water Resources, Res Ctr Pearl River Estuary & Coast, Guangzhou 510611, Peoples R China.
关键词：
thermal damage;basalt;uniaxial compression;acoustic emission;damage evolution;constitutive model
摘要：
Nuclear power is a high-quality clean energy source, but nuclear waste is generated during operation. The waste continuously releases heat during disposal, increasing the adjoining rock temperature and affecting the safety of the disposal site. Basalt is widely considered a commonly used rock type in the repository. This study of basalt’s mechanical characteristics and damage evolution after thermal damage, with its far-reaching engineering value, was conducted by combining experimental work and theory. Uniaxial compression tests were conducted on basalt exposed to 25 °C, 500 °C, 700 °C, 900 °C, and 1100 °C conditions, and acoustic emission (AE) equipment was utilized to observe the acoustic emission phenomenon during deformation. This study was carried out to examine the mechanical characteristics, the sound emission features, the progression of damage laws, and the stress–strain framework of basalt after exposure to different types of thermal harm. As the temperature rises, the rock’s maximum strength declines steadily, the peak strain rises in tandem, the rock sample’s ductility is augmented, the failure mode changes from shear to tensile failure, and cracks in the failure area are observed. At room temperature, the acoustic emission signal is more vigorous than in the initial stage of rock sample loading due to thermal damage; however, after the linear elastic stage is entered, its activity is lessened. In cases where the rock approaches collapse, there is a significant surge in acoustic emission activity, leading to the peak frequency of acoustic emission ringing. The cumulative ring count of acoustic emission serves as the basis for the definition of the damage variable. At room temperature, the damage evolution of rock samples can be broken down into four distinct stages. This defined damage variable is more reflective of the entire failure process. After exposure to high temperatures, the initial damage of the rock sample becomes more extensive, and the damage variable tends to be stable with strain evolution. The stress–strain constitutive model of basalt deformation is derived based on the crack axial strain law and acoustic emission parameters. A powerful relationship between theoretical and experimental curves is evident.
期刊：
International Journal of Environmental Research and Public Health,2022年19(11):6529- ISSN：1661-7827
通讯作者：
Jie Zhang
作者机构：
[Zhang, Xiaoling; Wang, Liangqin; Li, Jie; Song, Xin; Zeng, Taotao; Yang, Jinhui; Chen, Shengbing] Univ South China, Hunan Prov Key Lab Pollut Control & Resources Reu, Hengyang 421001, Peoples R China.;[Zhang, Jie] Harbin Inst Technol, State Key Lab Urban Water Resources & Environm, Harbin 150090, Peoples R China.
通讯机构：
[Jie Zhang] S;State Key Laboratory of Urban Water Resources and Environment, Harbin Institute of Technology, Harbin 150090, China<&wdkj&>Author to whom correspondence should be addressed.
