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Li H.-W.,Beijing Jiaotong University | Nie Q.-K.,Hebei Research Institute of Construction and Geotechnical Investigation Co.
Meitan Xuebao/Journal of the China Coal Society | Year: 2011

Based on a large number of measured data for pile-anchor retaining structures used in deep an excavation in-situ, the evolutions of ground surface settlements, the horizontal displacements, the cap beam horizontal displacements with time were analyzed. Besides, the evolutions of internal stress of retaining piles(i. e. the reinforcement stresses inside cap beam and retuning piles, bending moments of piles) and earth pressure distribution of piles were also discussed. Based on the dynamic evolution concept of deformation and force, the relationship between these physical values(i. e. the deformation and force) of retaining structures in space and with time was studied.

Nie Q.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Bai B.,Beijing Jiaotong University
Geotechnical Special Publication | Year: 2014

This paper investigates the consolidation and shear strength of compacted red clay samples (before and after inundation) in Guangxi, China through laboratory tests. The unconfined shear strength of both undisturbed and remolded specimens in the process of reducing or adding water content was also studied. The studies show that, in moisture-density curves, the maximum dry density of the remolded specimen is greater than that of the undisturbed specimen. However, the optimum water content of the former is smaller than that of the latter. When the compacted specimens are subjected to a vertical load, the vertical deformation reaches steady state in a short time with a small value. After inundation, the increment of the vertical deformation is also very small. However, the unconfined shear strength of the red clay specimens with slightly higher water content is much better than that of those with lower water content. The test results also show that the dehydration or humidity absorption has significant effect on the shear strength of red clay, especially for the remolded specimen. © 2014 American Society of Civil Engineers.

Zhao Q.,Yanshan University | Yu J.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Geng G.,University of California at Berkeley | Jiang J.,Nanjing Southeast University | Liu X.,Yanshan University
Construction and Building Materials | Year: 2016

In this paper, the effect of fiber types such as steel fiber, polyvinyl alcohol (PVA) fiber, polypropylene (PP) fiber and basalt fiber, on the creep of concrete after one-year-loading was studied and the principle of fiber's effect on concrete creep was analyzed. The elastic modulus of fibers is shown to be the most significant factor influencing concrete creep. Fibers with elastic modulus much higher than plain concrete can clearly restrict creep, while fibers with lower elastic modulus have the opposite effect. For example, 2% volumetric blending of steel fiber reduces specific creep by 25.1%, compared with plain concrete, while 0.9 kg/m3 mass blending of PVA fibers increases it by 19.9%. The internal defects introduced by fiber addition, i.e., the fiber-concrete interfacial zone and non-uniform fiber distribution, weakens its creep resistance. There is a clear correlation between the 28 days elastic modulus of fiber reinforced concrete (FRC) and its long-term creep behavior, indicating that they are influenced by similar factors. Larger elastic modulus at 28 days tends to yield less specific creep at 1 year. © 2015 Elsevier Ltd. All rights reserved.

Wu H.,Central South University | Huang B.,Tongji University | Huang B.,University of Tennessee at Knoxville | Shu X.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Yin J.,Central South University of forestry and Technology
Construction and Building Materials | Year: 2016

Due to increasing generation of solid wastes from papermaking industry, major concerns arise about the disposal of the solid wastes and their adverse impacts on environments, in which the disposal of paper sludge massively produced from paper mills has become one of the most serious solid waste problems worldwide. In this study, laboratory experiments were conducted to evaluate the feasibility and applicability of incorporating solid wastes from paper mills into controlled low strength material (CLSM), in which fly ash was used as a substitute for cement, bottom ash was added by partially replacing fine aggregate, and paper sludge was treated as a fibrous admixture. Results show that both fly ash and bottom ash could be effectively used in production of CLSM mixtures with desired performances. By limiting the amount of cement used in the mixture, the ultimate strength of CLSM could be controlled for easy excavation. Fly ash could effectively increase flowability of the mixture, thus improving self-compactibility. Both bottom ash and paper sludge had an adverse effect on the flowability. The strength of CLSM was reduced when a higher content of fly ash was incorporated to replace cement, while the strength was increased when more river sand was replaced with bottom ash. Due to a high water absorption and poor dispersibility of paper sludge, the CLSM made with additional paper sludge exhibited a relatively low flowability and a reduction in strength. However, with proper mixture design, paper sludge could still be effectively used in CLSM. © 2016 Elsevier Ltd. All rights reserved.

Meng L.,Shijiazhuang University | Zhang L.,Hebei Research Institute of Construction and Geotechnical Investigation Co. | Wang Z.,Shijiazhuang University
International Journal of Earth Sciences and Engineering | Year: 2015

The governing equation of fluid-solid coupling based on Biot’s consolidation theory is deduced. The excavation procedure of the pit is simulated to investigate the effect of different excavate rate on surface settlement, displacement of pile top, basement uplift, effective stress and excess pore-water pressure of the soil behind the pile. Simulation results show that the time effect has obviously influence on the stability of deep pit excavation, such as excavation rate, and excavation steps according to the stress path analysis. © 2015 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.

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