期刊：
Bulletin of Engineering Geology and the Environment,2019年78(6):4611-4622 ISSN：1435-9529
通讯作者：
Lu, Haijun
作者机构：
[Lu, Haijun; Xu, Shicheng; Li, Jixiang] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Hubei, Peoples R China.;[Lu, Haijun] Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.;[Liu, Junzhu] Beijing Geo & Inv Engn Inst, Beijing 100083, Peoples R China.
通讯机构：
[Lu, Haijun] W;[Lu, Haijun] C;Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Hubei, Peoples R China.;Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.
关键词：
Structured clay;Landfill leachate;Triaxial shear test;Microstructure;Particle distribution
摘要：
City solid waste stock has exceeded 8 billion tons in China, and the output and coverage area of solid waste are increasing daily. Landfill leachate can be generated during biodegradation of disposed and stored solid waste. Leachate contains high concentrations of organic mixtures and heavy metal ions. Natural undisturbed soil has high anti-seepage capacity and its permeability coefficient is less than 1 x 10(-7) cm/s in underlying stratum, which can delay leachate contamination of the environment surrounding a landfill site. However, undisturbed soil exhibits certain structural characteristics. After long-term leachate corrosion, leachate leakage will inevitably influence the stability of stratum underlying a landfill. In this study, the mechanical characteristics of undisturbed clay under the actions of landfill leachate and stress were analyzed via a consolidated-undrained triaxial shear test. Comprehensive microstructure laboratory tests, including X-ray diffraction, scanning electron microscopy, and laser particle size tests, were performed to determine at different times the microstructure of undisturbed clay due to corrosion by landfill leachate. Experimental results indicate the strength and microstructural evolution of structured clay under the actions of landfill leachate and stress. The research results are helpful for evaluating the safety and predicting the stability of a landfill's underlying stratum.
摘要：
To investigate the shear strength and microstructure of undisturbed loess polluted by landfill leachate, a series of laboratory tests were carried out to determine the shear strength, mineral composition, surface morphology, particle size distribution and pore characteristics of the loess. The stress-strain curve of undisturbed soil polluted by landfill leachate showed typical strain-softening behavior. The deviatoric stress, cohesion and angle of shearing resistance of undisturbed soil decreased at increased landfill leachate concentrations, decreased by 31.03%, 30.01%, respectively. But pore water pressure was positively related to leachate concentrations. The content of primary minerals remained stable, and the content of montmorillonite and illite decreased with increased leachate concentration, reduced by 26.02%, 23.93%, respectively. Soil structure changed into an unstable honeycomb structure when the leachate concentration increased. Moreover, the average particle size decreased by 62.1%, and the specific surface area increased and then stabilized at 500 similar to 650 m(2)/kg. The soil particles became nonuniform and porous and their sizes gradually decreased. The pore radius of soil mainly ranged from 0.02 mu m to 1 mu m. The maximum radius and optimal radius of the pore increased when the leachate concentrations increased.
摘要：
In order to reasonably predict failure law of compacted clay presented in landfill leachate as well as help provide theoretical basis for curbing and restoration of contaminated soil, triaxial shear, SEM, XRD and laser particle size tests were used to determine strength and microstructure of compacted clay presented in landfill leachate in this paper. The results show that when the leachate concentration was low, the stress-strain curve of compacted clay belonged to typical strain-softening behavior. With the increase of leachate concentration, the stress-strain curve of soil began to show typical strain-hardening behavior. The concentration of leachate was negatively related to the cohesion and internal friction angle of soil sample. In the aspect of soil microstructure, with the increase of leachate concentration, a series of microstructural changes, such as a decrease of secondary minerals, an increase of pore, the overhead pores developed into cracks and so on, had result in a decrease of the strength of compacted clay. The particle size curve of compacted clay presented in landfill leachate was about single peak curve and the value of D-v(50) tend to stable.
摘要：
为研究刚性聚丙烯纤维改性透水混凝土材料作为道路面层的路用性能以及对土基层稳定性的影响,实验室中制作了4组透水混凝土路段模型,实测刚性聚丙烯纤维改性透水混凝土面层的渗透系数为3.13 cm/s,较普通透水混凝土路面具备更优的渗透性能;模拟刚性聚丙烯纤维改性透水混凝土路面在干燥状态及降雨水饱和状态下的承载试验,得到模型路段的标准轴载承载力分别为98和86 k N,较普通透水混凝土路面承载力分别提高了49%和62%。在同种状态的土基上加载,纤维模型路段较普通模型路段有更强的抗弯沉变形能力,相同荷载下刚性聚丙烯纤维路段各点沉降量减小且较均匀,表现出更佳的整体工作性能。
作者机构：
[朱登峰; 李继祥; 杨建康] Institute of Poromechanics, Wuhan Polytechnic University, Wuhan, 430023, China;Institute of Geotechnical Engineering, School of Civil Engineering, Dalian University of Technology, Dalian, 116024, China;[陆海军] Institute of Poromechanics, Wuhan Polytechnic University, Wuhan, 430023, China, Institute of Geotechnical Engineering, School of Civil Engineering, Dalian University of Technology, Dalian, 116024, China
通讯机构：
[Lu, H.-J.] I;Institute of Poromechanics, Wuhan Polytechnic University, Wuhan, China
摘要：
In the present paper, the addition of silane to improve the properties of mortar was experimentally investigated. The morphology and microstructure of mortar were investigated by using both scanning electron microscopy (SEM) and polarizing microscopy (PM). The results show that silane significantly alters the microstructure of mortar, reduces the crystallization, restricts the degree of hydration of cement-based materials, and decreases micro-voids. As a result, silane effectively improves the chemical and carbonation resistance, as well as the chloride and water penetration resistance of mortar. Results also indicate that the consistency of mortar was improved but the compressive strength of the mortar was decreased. Specifically, silane would also be beneficial to the bridging cracking function to resist crack propagation.
摘要：
In order to research the corrosive state of landfill liner system, which affected by landfill leachate, and explore its strength and microstructure properties, contacting reaction between landfill leachate and compacted clay landfill liner system was simulated. Then, clay samples of different layers were investigated by unconfined compressive testing, shear testing and static nitrogen adsorption testing. The results showed that corrosion degree of clay samples caused by landfill leachate increased with the decrease of deepness of clay. And the maximum unconfined compressive strength (UCS) decreased obviously along with the shear strength. The UCS at 10cm was 53.1% that of layer at 50cm and the shear strength was 40.4∼62.4% at 10cm that of 50cm. The static nitrogen adsorption testing showed that the shape of clay particle was bottleneck like, and with the decrease of the depth of clay, there was a decrease in the number of micropores whose size was no smaller than 6nm. And the number of pores which was between 2nm and 5nm increased. In addition, there also appeared micropore which was smaller than 2nm. And the average pore size was decreased from 5.083nm at 50cm to 3.768nm at 10cm.<br/>
