摘要：
Controlling the water content in soil is crucial for the load bearing capacity of soil. In the past few decades, electroosmosis has been proved to be a versatile strategy to consolidate soil in situ. However, the efficiency of this electrochemical technique needs to be further improved for practical application. This study was designed to test the hypothesis that the incorporation of nanoparticles (NPs) during electroosmosis can significantly facilitate the migration of water molecules under an external electric field and thus improve the physical properties of the treated soil. In addition, the number of anodes per cathode was explored as another method to improve the efficiency of electroosmosis in dewatering and strengthening soil. The results from the designed laboratory experiments confirmed the benefits of increasing the number of anodes or adding positively charged SiO2@Al2O3 core–shell NPs, in increasing the dewatering rate and improving the cohesion, internal friction angle, and microstructure of the treated soil (Lake Silt). The finite element method based simulation results agreed well with the experimental observations and suggested that the NPs can promote the water migration under an electric field.
关键词：
Alternating pulse electric field;Calcium chloride;Electroosmosis;Reinforcement;Scanning electron microscopy;Weak soil
摘要：
Electroosmosis has been extensively employed as an effective method for the dewatering treatment of soils and thus the reinforcement of weak soils. At the microscopic level, this treatment process is inherently complex due to in situ chemical and electrochemical reactions, migration of ions and particles, and the dependence of zeta potential of various particles on the local pH value in the soil. This complexity has hindered further understanding of mechanisms underlying the electroosmosis technology. Here, we design an external electric field in which alternating pulse wave potentials were partially used to adjust the pH value of the soil and manipulate the dynamics of in situ formed nanoparticles and their interconnectivity. The experimental results reveal that the in situ formation of Ca-rich particles, instead of water drainage, may serve as the main mechanism underlying the observed soil reinforcement when using calcium chloride as the treatment electrolyte. The interconnectivity of such particles may be the key for the shear strength improvement without significant settlement of the soil.
摘要：
Suction-controlled triaxial tests have been used extensively to characterize unsaturated soils. However, this type of tests requires sophisticated and therefore expensive equipment and is very time-consuming. These limitations have been the main obstacles for research, dissemination, and implementation of unsaturated soil mechanics in engineering practice. Compared with the suction-controlled triaxial test apparatus, an oedometer for saturated soils is much simpler. It is 300 to 400 times more efficient to run a constant water content oedometer test for unsaturated soils than a suction-controlled triaxial test. The major disadvantage of the constant water content oedometer test is that its stress path is difficult to analyze and no method is available to take advantage of the test results for constitutive modeling purposes. In this paper, a conventional oedometer for saturated soils was modified to characterize unsaturated soils under constant water content compression. An analysis method was also developed to use the results directly from constant water content oedometer tests for constitutive modeling. A series of constant water content oedometer tests was used to demonstrate the application of the proposed method from which the capability and the effectiveness of the proposed developments were evaluated. With developments in equipment and analysis, it is now possible to characterize unsaturated soils rapidly in a simple and efficient way.
作者机构：
[Xu, Shuping; Zhang, Heng; Zhou, Guoxiang] Wuhan Polytech Inst, Sch Civil Engn, Wuhan 430023, Peoples R China.;[Gui, Xuchun] Sun Yat Sen Univ, Sch Phys & Engn, State Key Lab Optoelect Mat & Technol, Guangzhou 510275, Guangdong, Peoples R China.;[Wei, Hongqiu; Leng, Jinsong] Harbin Inst Technol, Ctr Composite Mat & Struct, Harbin 150080, Peoples R China.;[Koratkar, Nikhil] Rensselaer Polytech Inst, Dept Mech Aerosp & Nucl Engn, Troy, NY 12180 USA.;[Zhong, Jing; Zhang, Heng; Zhou, Guoxiang] Harbin Inst Technol, Sch Civil Engn, Harbin 150090, Peoples R China.
通讯机构：
[Gui, Xuchun] S;[Zhong, Jing] H;Sun Yat Sen Univ, Sch Phys & Engn, State Key Lab Optoelect Mat & Technol, Guangzhou 510275, Guangdong, Peoples R China.;Harbin Inst Technol, Sch Civil Engn, Harbin 150090, Peoples R China.;Harbin Inst Technol, Minist Educ, Key Lab Struct Dynam Behav & Control, Harbin 150090, Heilongjiang, Peoples R China.
摘要：
In this work, a 3-D porous carbon nanotube sponge (CNTS) was embedded within a shape memory polymer (SMPs) matrix. We demonstrate complete infiltration and filling of the SMPs into the CNTS by capillary force without any damage to the CNTS structure. With only ~0.2 wt% carbon nanotube loading, the glass transition temperature is increased by ~20 °C, indicating strong interaction between CNTS and the SMPs matrix. Further, we find that the uniform distribution of the carbon nanotubes in the nanocomposite results in high electrical conductivity, and thus highly effective electricity triggering capability. The carbon nanotube sponge shape memory polymer (CNTS/SMPs) nanocomposite could be triggered within ~10 seconds by the application of ~10 volts. Results from finite element simulations showed good agreement with the experimental results, and indicated that for our system the interface thermal energy loss does not have a significant effect on the heating rate of the polymer matrix.
期刊：
International Journal of Electrochemical Science,2016年11(7):6023-6042 ISSN：1452-3981
通讯作者：
Li, Yongxin;Shi, Xianming
作者机构：
[Wang, Dongmei; Xiao, Xiaoqing; Li, Yongxin] Anhui Normal Univ, Coll Chem & Mat Sci, Wuhu 241000, Peoples R China.;[Shi, Xianming] Washington State Univ, Dept Civil & Environm Engn, POB 642910, Pullman, WA 99164 USA.;[Shi, Xianming] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Wuhan 430023, Peoples R China.;[Li, Yongxin; Shi, Xianming; Jackson, Emily; Xie, Ning; Zhang, Yan; Fang, Yida] Montana State Univ, Western Transportat Inst, Bozeman, MT 59717 USA.
通讯机构：
[Li, Yongxin] A;[Shi, Xianming] W;[Li, YX; Shi, XM] M;Anhui Normal Univ, Coll Chem & Mat Sci, Wuhu 241000, Peoples R China.;Washington State Univ, Dept Civil & Environm Engn, POB 642910, Pullman, WA 99164 USA.
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：
A total of 12 multielectrode array sensors were utilized to assess the individual effectiveness of two corrosion inhibitors and one coating under cyclic deicer exposure conditions. There were four sensor groups, and each group consisted of nine-pin probes that were fabricated from 1008 carbon steel, 304 stainless steel, and 1100 aluminum, respectively. A total of two environmental exposure tests were conducted, in which 2.3% NaCl and 3.0% MgCl2 solutions were used as salt, respectively. The two tests each included eight environmental cycles and with 24h per cycle. For all the exposed sensors, the most severe corrosion occurred at the beginning of the humidity stage. For sensors in the control group, MgCl2 exhibited a corrosion attack throughout the exposure period, whereas NaCl only exhibited an apparent corrosion attack during the humidity stage. Both the sensor corrosion rates and mass loss results indicate that the inhibitors had a much greater effect for MgCl2 than for NaCl. Although the coating showed significant benefits in protecting the metallic substrates, the cyclic exposure to MgCl2 led to greater coating deterioration than did NaCl. For validation, impedance measurements were conducted on carbon steel panels subjected to similar exposures, and three-dimensional laser profilometer scans were performed to characterize their surface morphology after the exposures.
作者机构：
[Song, Rui; Liu, Jianjun; Cui, Mengmeng] Southwest Petr Univ, Chengdu 610500, Peoples R China.;[Liu, Jianjun] Wuhan Polytech Univ, Inst PoroMech, Wuhan 430023, Peoples R China.;[Wang, Wei] Nanyang Cent Hosp, Ultrasound Div, Nanyang 473000, Peoples R China.
通讯机构：
[Liu, Jianjun] S;[Liu, Jianjun] W;Southwest Petr Univ, Chengdu 610500, Peoples R China.;Wuhan Polytech Univ, Inst PoroMech, Wuhan 430023, Peoples R China.
关键词：
ANSYS and LS-DYNA;CT scanning image;Dynamic simulation;Lumbar vertebrae and pelvis
摘要：
Introduction: Analysis of the dynamic mechanism of lumbar vertebrae and pelvis in human falls is of great importance both academically and in practice. Materials and methods: Using CT scanning of the human body, the finite element model of the lumbar vertebrae and pelvis was reconstructed by Amira and ICEM software. Dynamic simulations for different landing postures and falling height were conducted by coupling the ANSYS and LS-DYNA software Results: The dynamic simulation was able to reproduce the landing process of the human body and the injured sites. Discussion: Results indicate that different landing postures will cause different injury sites, sloping posture will result in serious injury and bone fracture is usually caused by shear force.
摘要：
The study presented in this paper focuses on an experimental investigation of cement mortar incorporated lauric acid/expanded perlite phase-change materials (PCMs). The physical properties of mortar incorporated shape-stable PCMs (SSPCMs) were evaluated. The results showed that the addition of SSPCM increased the water absorption of mortar, reduced the bulk density, and thermal conductivity coefficient of SSPCM mortar. Microstructure was studied for SSPCM composite in mortar. Scanning electron microscope (SEM) imaging indicated that most SSPCM granular particles were evenly distributed into the cement matrix after the mechanical strength test, and the SSPCM are in good bond with the cement binder. The temperature-control test revealed that the temperature adjustment properties of samples incorporating SSPCM was significantly greater than that of the reference mortar, and SSPCM-integrated mortar is thermally reliable because of the fact that the SSPCM mortars showed no degradation in thermal performance after multiple thermal cycles.
