通讯机构：
[Liu, JS ] W;Wuhan Polytech Univ, Sch Civil Engn & Architecture, 68 Xuefu S Rd, Wuhan 430023, Hubei, Peoples R China.;Wuhan Polytech Univ, Pilot Scale Platform Marine Engn Struct Protect Ma, 68 Xuefu S Rd, Wuhan 430023, Hubei, Peoples R China.
关键词：
geopolymer;steel slag;flue gas desulfurization gypsum;grouting material;mechanical properties
摘要：
In this paper, the performance of steel slag (SS) and flue gas desulfurization (FGD) gypsum modified metakaolin-based geopolymer (MGP) was studied for the purpose of industrial solid waste reuse, and a new geopolymer grouting material was obtained. The setting time, fluidity, bulk density, and compressive strength of MGP containing different mass contents of solid waste materials were studied through a series of tests. In addition, the microstructure mechanism of MGP was analyzed using scanning electron microscopy and Fourier transformation infrared spectroscope. The results show that the setting time of MGP increases with the increase of SS content, whereas the setting time decreases with the increase of FGD content. The addition of SS or FGD slightly reduces the fluidity of MGP. Adding an appropriate amount of SS to MGP can significantly improve the later compressive strength of the specimen, whereas adding an appropriate amount of FGD can improve the compressive strength of the specimen, especially the early compressive strength. When the SS content was 4 %, the hardened MGP exhibited the best properties in compressive strength and bulk density. The formation of amorphous geopolymer gel products in MGP matrix was promoted by the addition of SS and FGD. These results will be beneficial to the production of new environmentally friendly and low-cost MGP grouting materials, which can improve the comprehensive utilization level of SS and FGD and achieve the purpose of protecting the ecological environment.
作者机构：
[Liu, Mengyi; Lu, Haijun; Dong, Yiqie; Zang, Meng; Zang, M; Lu, HJ] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Liu, Mengyi; Lu, Haijun; Lu, HJ] Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.;[Cai, Guanghua] Nanjing Forestry Univ, Coll Civil Engn, Nanjing 210037, Peoples R China.
通讯机构：
[Zang, M; Lu, HJ ] W;Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.
关键词：
lake sediment;solidification/stabilization;industrial solid waste;water permeability;microstructure
摘要：
Occupation of land and damage to the surrounding ecosystem may occur due to the accumulation of dredged lake sediments. In order to solve the large amount of dredged lake sediments, industrial wastes (slag, desulfurization gypsum) and urban construction waste were used to solidify the lake substrate, obtained a new construction material. Water content, volumetric shrinkage, unconfined compressive strength and flexural strength parameters and hydraulic conductivity coefficients of the solidified sediment were obtained from water content determination tests, volumetric shrinkage tests, unconfined compressive strength tests, flexural tests and permeation tests. Mineralogical composition and microstructural characterization of the solidified sediment using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were obtained. The solidification mechanism of lake sediment under the coupling of industrial waste and urban construction waste was revealed. The water content of the specimens decreased rapidly, and shrinkage deformation occurred in curing for 7 d. The volumetric shrinkage of 28 d was eventually maintained at 1.27-5.19%. The trend of specimen strength changed with the extension of time in the overall increase state, the compressive strength and flexural strength within 28 d were 3.15-10.96 MPa and 0.64-2.69 MPa, respectively. The solidified sediment material showed excellent anti-seepage performance, the hydraulic conductivity reached stability at 1.22 x 10(-8)-55.4 x 10(-8) cm/s. Gismondine, gypsum, calcite, scawtite and fibrous C-S-H phases were generated in the solidified material.
关键词：
Metro depot;throat area;curved and straight tracks;track locations;low-rise steel-framed structure;measurements;train-induced vibration;assessments
摘要：
Train-induced feelable vibrations can bring side effects to people living or working in the building, as well as to operation of precise equipment. As massive construction of over-track buildings above metro depots prevails in megacities, impacts from train-induced feelable vibration take more concern. Four standard-designed 4-story steel-framed offices above the throat area in the Qianhai metro depot in Shenzhen, China, are studied in this research. The field measurements were conducted to investigate the influences of track alignment and track location in the throat area on vibration responses of over-track buildings. Detailed vibration analyses using the finite element method have been conducted. Train-induced floor vibration assessments on human comfort are carried out based on a total of 54 train pass-bys operated in the morning and evening and on different tracks. It can be found that the track alignment primarily affected the higher frequency components of train-induced vibrations, where curved trackinduced vibrations have larger amplitudes. The variance of train-induced building vibrations among pass-bys on different track locations was reduced compared with that of ground vibrations because of the averaging effects caused by multiple transmitting paths within the massive platform and stiff transfer structures. Train-induced acceleration levels at mid-floor can be 20-25 dB larger than those near columns at floor resonance frequencies which are dependent on the structural design. This research gives a comprehensive insight into train-induced vibrations within low-rise steel-framed buildings above the throat area in the metro depot, which is a valuable reference for assessments before the construction of future similar over-track communities.
摘要：
This study explored the effect of Cr3C2 content (0, 0.5, 1, 1.5, and 2 mol%) on the microstructure, magnetic properties and mechanical behavior of TiC-10TiN-6WC-4C-(15,30) Ni (mol%) cermets after vacuum sintering. The results show that just Ti-based carbonitride ceramic grains and Ni-based binder phase were presented in the experimental cermets, and the mean size of ceramic grains reduced with the increase of Cr3C2 content. By adding Cr3C2 into cermets, the Cr concentration in binder phase obviously raised. However, Ti concentration in binder phase decreased continuously as Cr3C2 content increased, while the W concentration remained nearly constant. Saturation magnetization and remanence of cermets decreased with increasing Cr3C2 content, which was pri-marily ascribed to the increased amounts of antiferromagnetic Cr element in the Ni-based binder phase. When Cr3C2 content exceeded 0.5 mol%, cermets became paramagnetic at room temperature. Cermets with 15 and 30 mol% Ni had Curie temperatures of roughly 138 K and 28 K by 2 mol% Cr3C2 addition, respectively. Therefore, Cr3C2 addition is very effective in suppressing the ferromagnetism of cermets. Moreover, transverse rupture strength and hardness of cermets first raised and then declined with the addition of Cr3C2.
摘要：
Stabilizing heavy metal-contaminated soil with solid waste-based materials is a sustainable approach. This study synthesized a coal bottom ash-based geopolymer and coir for the treatment of Cd- and Pb-contaminated soil. The results demonstrated that adding 10% geopolymer stabilized over 95% of Cd and Pb in contaminated soil, with the maximum compressive strength of soil reaching 634 kPa after curing. Geochemical model simulations revealed that Pb and Cd primarily converted to precipitated mineral forms (Cd4(OH)6SO4, Pb4(OH)6SO4, Litharge, and larnakite) when the system pH exceeded 5. From a mechanical perspective, the combination of coir and coal bottom ash-based geopolymers effectively solidified heavy metals while improving soil frost resistance, compression resistance, and shear resistance. The mineral recombination of coal bottom ash was successfully achieved, and it was prepared as an amorphous cementitious material. This study unveils the mechanism of geopolymer-cemented heavy metals and their structural strengthening, providing new technologies for addressing land resource pollution and realizing the green, sustainable, and clean reuse of industrial solid waste.
摘要：
There are numerous tunnels worldwide that cross active fault zones. These tunnels are situated in complex geological environments and are subjected to intense seismic activities. When active fault zones experience displacement, tunnels are susceptible to varying degrees of damage. Over the past few decades, many scholars have researched tunnels crossing active fault zones using numerical simulation methods, including finite element analysis, discrete element analysis, and finite difference methods. However, certain aspects have been overlooked, such as the influence of burial depth on tunnels crossing active fault zones. Most prior studies have primarily omitted consideration of tunnel depth and high-stress effects, resulting in disparities between research findings and practical engineering outcomes. In light of these issues, this paper analyzes the impact of ground stress fields at different burial depths on tunnels crossing active fault zones. It compares the mechanical response characteristics of deep-buried and shallow-buried tunnels after experiencing fault displacement, elucidating variations in displacement patterns, stress, and strain at different burial depths. The results indicate that: (1) Deep-buried and shallow-buried tunnels exhibit an "S"-shaped deformation pattern. (2) Regarding the strain distribution within the tunnel, the affected regions are predominantly concentrated within the fault zone. (3) Regarding the stress distribution within the tunnel, deep-buried tunnels experience a broader range of stress variations distributed across the fault zone. In contrast, shallow-buried tunnels predominantly exhibit stress concentration at the fault slip plane. (4) By analyzing the patterns of tunnel damage at different burial depths, it is observed that burial-depth effects notably influence tunnels with a burial depth less than 200 m. In comparison, tunnels exceeding 300 m gradually reduce the impact of burial depth. These findings can be essential theoretical references for studying tunnels crossing active fault zones in deep-buried environments.
