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Wei G.-X.,Tianjin Chengjian University | Liu H.-Q.,Tianjin Chengjian University | Liu H.-Q.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment | Liu F.,Tianjin Chengjian University | And 3 more authors.
Aerosol and Air Quality Research | Year: 2017

Flotation has been proven to successfully remove most polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and carbon constituents from hospital solid waste incinerator (HSWI) fly ash. The resultant froths contain large quantities of carbon constituents that can reburn in the incinerator. In this paper, the reburning behavior of froths at temperatures from 800°C to 1200°C was compared with that of HSWI fly ash. Results showed that the destruction efficiency of PCDD/Fs was higher in the froths than in the fly ash at the same reburning temperature. The destruction efficiencies of PCDD/Fs in the froths exceeded 98% at temperatures higher than 1000°C. The volatilization ratio of Pb, Zn, and Cu was lower in the froths than in the fly ash. Furthermore, reburning of the froths can achieve energy recovery of the carbon constituents. Therefore, flotation followed by reburning treatment in a combustion chamber could be a suitable process for the detoxification and reutilization of HSWI fly ash. © Taiwan Association for Aerosol Research.


Li S.-Q.,Tianjin Institute of Urban Construction | Li S.-Q.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment | Zheng G.,Tianjin University | Wang Y.-H.,Tianjin Institute of Urban Construction
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

The earth pressure theory by Rankine and the formula for calculating subsidiary stress by Boussinesq were employed to study the interaction between earth berm and retaining structure for cantilever retaining structure. On one hand, the earth berm in a pit can strengthen horizontal resisting force of the soil body in the passive zone owing to its gravity. On the other hand, it can reinforce the stability of the retaining structure due to the horizontal resisting force of itself. Considering the two points aforementioned, a method is constructed to determine embedment depth of retaining structures. And more, a pit excavation is computed by the proposed method for further investigations. The study shows that reinforcement of the earth berm on retaining structure is remarkable because of the large moment arm even the magnitude of the horizontal resisting force is not very great. Therefore, the needed embedment length of the retaining structure in the pit excavation having earth berm can be distinctly cut. It can be concluded that the earth berm method should be recommended in suitable situations for its better economy, higher efficiency and lower pollution.


Li S.-Q.,Tianjin Institute of Urban Construction | Li S.-Q.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment | Zheng G.,Tianjin University | Wang Y.-H.,Tianjin Institute of Urban Construction
Gongcheng Lixue/Engineering Mechanics | Year: 2012

Based on the technical specification for retaining and protection of building foundation pit and strength theory for unsaturated soils, computational methods are constructed for embedded depth, displacement and inner force determination of retaining structure for unsaturated pit. The mechanical studies show that the functions of earth berm for unsaturated pit include two aspects. The first one is that the necessary embedded depth of the retaining structure can be reduced because of the longer force arm of the horizontal resisting force. And the second one is that the displacement and inner force of the retaining structure can be reduced for its horizontal elastic ssupporting. Analysis on an example illustrates that the construction method using earth berm in pit excavation together with lowering groundwater can decrease the embedded depth, displacement and inner force of retaining structure remarkably. Therefore, the construction method is economical due to sparing horizontal supporting structure as well as reducing project time.


Li S.-Q.,Chinese Academy of Sciences | Li S.-Q.,Tianjin Institute of Urban Construction | Li S.-Q.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment | Gao L.-X.,Chinese Academy of Sciences | And 3 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

The mechanical properties of frozen soil depend on not only the single factor, such as water content, temperature, strain rate, salt content, confining pressure etc., but also on the possible interaction between the mentioned factors. In order to make sure of the dependence relationship of frozen soil strength and modulus with these factors, the significant and interaction of influencing factors of frozen soil mechanical properties is studied according to the experimental data and statistics theory. The study shows that the mentioned factors have obvious influence on the mechanical properties of frozen soils; however the factor of temperature is the most important one. Furthermore, the interactions on strength, which originating between temperature, water content and strain rate, are found to be obvious enough and can't be neglected. Therefore, it is not rational that only some separate factors are taken into account as studying the mechanical properties. The most appropriate method is to study it in overall factors and with the interaction taken into consideration.


Li S.-Q.,Tianjin Chengjian University | Li S.-Q.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment | Xia J.-H.,Xinxiang University | Zhang P.-Y.,Tianjin Chengjian University
Gongcheng Lixue/Engineering Mechanics | Year: 2016

The particular structure, which was constructed by the initial stress in consolidation, is the key role to answer the remarkably mechanical difference between remolded soil and undisturbed soil. The yield surface for remolded soil in a three principle stress space, always takes the isoclinic line as its axis due to isotropy. It is rational that the initial stress line, but not the isoclinic line, should be set as the axis of the yield surface for undisturbed soil because the stress state in original position is not spherical. As a foreword, the generalized yield shear stresses which had been achieved from some true triaxial tests at constant p, were analyzed with respect to a loading angle. Subsequently, the concept of an initial stress line was put forward owing to the initial stress state of undisturbed soil. And the relationship between an isoclinic line and an initial stress line was discussed. Together with the generalized plasticity mechanics, three modified Mohr-Coulomb yield criteria, namely translation model, translation model, and revolution model, were built to simulate the shear yield of undisturbed soil. The yield traces of the first two modified criteria are all located on a traditional π plane. While the yield trace of the revolution model is located on a χ plane, which is vertical to the initial stress line. Therefore, the first two models can be utilized to simulate true triaxial tests at constant p. And the last one can be employed to simulate true triaxial tests at σ1+K0σ2+K0σ3=c or data transformed from a π plane to a χ plane. Reference verification has illustrated that the revolution model derivated from Mohr-Coulomb yield criterion could reflect the structure and anisotropy of undisturbed soil in mechanics. Furthermore, every variable parameter in the third model has an explicit physical meaning. © 2016, Engineering Mechanics Press. All right reserved.


Yang B.Z.,Tianjin Chengjian University | Zhang S.C.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment
Applied Mechanics and Materials | Year: 2013

Supper-deep diaphragm wall construction of a Tianjin traffic hub project penetrated through many soil layers and two layers of confined water, geological and hydraulic conditions were complicated. Some special technologies including grooving methods, anti-collapse measures, verticality controlling measures, joint treatment measures and steel reinforcement cage hoisting measures were adopted for the construction. The project was finished with short time, low cost and good quality. Engineering practice shows that these technologies were appropriate for constructing supper-deep diaphragm wall under complicated geological and hydraulic conditions. These experiences can give some references to the similar super-deep diaphragm wall construction of Tianjin and other regions in future. © (2013) Trans Tech Publications, Switzerland.


Yang B.Z.,Tianjin University | Zhang S.C.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment | Luan K.Y.,Tianjin Huasha Artisans Architectural Design Co.
Applied Mechanics and Materials | Year: 2013

Two subway stations of line Z1 were built in Tianjin cultural center and Tianjin Yujiapu traffic hub. The diaphragm wall depth of the two stations was more than 60 m. The geological and hydraulic conditions were different in the two site. Keeping stability of slot wall was the key of supper-deep diaphragm wall construction to the both stations. Two 3D numerical models were built by ABQUS software to simulate the grooving process. The conditions of different slurry specific gravity and grooving depth were calculated. The deformation laws of the slot wall and ground settlement around the slot wall were studied. The results showed the upper soft silty clay and deeper silty sand layers were easy collapse. Finally, some technologies such as "] [" type guide wall, properly improving slurry specific gravity, soil cement mixing reinforcement were suggested to improve the stability during the diaphragm wall construction of the two stations. © (2013) Trans Tech Publications, Switzerland.


Li Z.-L.,Tianjin University | Li Z.-L.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment | Xue J.,Tianjin University
Applied Mechanics and Materials | Year: 2013

The structure of cable-stayed bridge with inclined and arched tower is complex and the force is complicated, especially the pylon, whose design and construction require detailed calculation and analysis. In case of the construction of Datong Nansanhuan Yuhe bridge project, in order to ensure the safety during its construction, the detailed construction plan was planned and the finite element model was established to analyse the dynamic performance of structure during construction of pylon. The result shows that, during the construction of low pylon, each frequency order of bridge structure is reduced to a steady level with the pylon completed gradually, and the low frequency changes moderately. © (2013) Trans Tech Publications, Switzerland.


Tao Y.,Zhejiang University | Tao Y.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment | Zhou J.,Zhejiang University | Gong X.,Zhejiang University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2013

Laboratory tests of typical Hangzhou soft soil were conducted to investigate the electroosmosis effects of ferrum, graphite, copper and aluminum electrode under the voltage gradient of 1.58, 0.79 and 0.53 V/cm respectively. By monitoring and analyzing drainage, effective voltage, water content reduction and energy consumed of each test, the following conclusions were drawn. Differences of the electroosmosis effects of ferrum, graphite, copper and aluminum electrode decrease with the drop of voltage gradient. Under higher voltage gradient, ferrum and graphite electrode performs quite accordance and their electroosmosis effects are much better than copper electrode. While with a relative lower voltage gradient, copper electrode displays slightly better than ferrum electrode, which again has a better performance over graphite electrode. Aluminum electrode represents the worst performance under all circumstances investigated. The conclusions can be reached by comparing the above results with former results that graphite electrode occupies a better performance over ferrum and copper electrode under higher voltage gradient, while performs worse than the other two electrodes under lower voltage gradient. In the real practice, the mineral constituent or ionic composition of the soil should be analyzed to select the optimum electrode material. Moreover, ferrum electrode is recommended as a preferential alternative in the electroosmosis strengthening of the soft soil in the coastal area of Zhejiang Province, while aluminum electrode is not suggested.


Tao Y.-L.,Zhejiang University | Tao Y.-L.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment | Zhou J.,Zhejiang University | Gong X.-N.,Zhejiang University | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

Laboratory tests are conducted to investigate the influence of ferrum and cuprum electrodes on electroosmotic effects, and they are analyzed and compared through drainage, voltage loss at the electrodes and water content monitoring. The results demonstrate a better performance of ferrum electrode than that of cuprum electrode. In the case of cuprum anode, a rapid decrease in current is observed for 4~6 hours after the test commences, together with a big voltage loss at the anode. Furthermore, the influence of different combinations of cathode and anode materials on electroosmosis is also explored. It is revealed that the anode materials occupy a leading role in electroosmosis while the cathode materials display little effect. A reasonable explanation to the laboratory findings in terms of electrochemistry is also given. The phenomenon of electrochemical passivation is first discovered in elecroosmosis. The electrochemical passivation will reduce the efficiency of elecroosmosis substantially and should be avoided in practical engineering.

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