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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. Source


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. Source


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. Source


Lu Q.,Tianjin Chengjian University | Lu Q.,Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment | Zhang B.,Tianjin Chengjian University | Wang L.,Tianjin Chengjian University
World Information on Earthquake Engineering | Year: 2015

The orthogonal test method with 4 different factors, including the water-cement ratio(A), the recycled coarse aggregate content to total coarse aggregate content(B), the content of polypropylene fiber(C) and confining pressure(D), was applied to the study of the compressive strength and deformation performance of fiber recycled concrete under conventional triaxial compression. 16 groups of fiber recycled concrete were made to analyze the above two kinds of performance. The results indicate that the peak stress under the condition of conventional triaxial compression has a linear relationship with uniaxial compressive strength and confining pressure. The peak stress and peak strain are conspicuously influenced by D, then A, but not significantly influenced by B and C. ©, 2015, Science and Technology Periodical Press. All right reserved. Source


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. Source

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