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Research On Mechanism Of Silty Soft Clay Under Impact Loading And Its Application

Posted on:2004-02-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:Q S MengFull Text:PDF
GTID:1102360185997307Subject:Geotechnical engineering
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Dynamic consolidation by drainage was shown effective method of soft clay ground treatment from more and more theoretical research and engineering practice. The essential of this method was that paving the native filling and crushed stone on saturated silty soft clay, the material has better penetrability and would come into being"incrustation layer"under impact loading. This layer act as the carrier that diffuse the stress came from impact energy into deeply soft clay, so the pore water pressure that exploded by impact loading would drained along the dimensional drainage network in the saturated soft clay, the soft clay was consolidated, and have much greater shear strength than before. The mechanism and technical process of silty soft clay under dynamic consolidation by drainage were systematically studied in virtue of dynamic knowledge of soil.Firstly, in this thesis, the engineering characteristic of saturated soft clay which taken from Qinzhou port were evaluated. The contrast analyze of relation between physics and mechanics were carried through after and before dynamic consolidation. The device project of laboratory equipment dynamic consolidation was expounded, its feasibility were affirmed. The impact stress, pore water pressure and deformation characteristics of saturated silty soft clay under impact loading in laboratory tests were studied systematically, and the ascertain methods of technical process such as saturated impact energy, appropriate number of impact, the times impact loading , the order of dynamic loading infliction and so on were put forward.Secondly, the laboratory tests about dynamic characteristic of natural soil and reconstituted soil under impact loading from these aspects, such as the use of drainage measure, different consolidation states and compressive stress around samples, and so on. The differences about dynamic characteristic between natural soil and reconstituted soil were shown from the tests, it is undemanding to study natural soil depend on tests about reconstituted soil because the natural soil has structural characteristic, however reconstituted has none. While it has important reference significance to study basal disciplinarian about natural soil from the dynamic characteristic of reconstituted soil.Thirdly, the pore water pressure generation and dissipation under impact loading obey hyperbola model, moreover axial deformation obey hyperbola-logarithm model. The method to ascertain the damage point of process harden type stress-strain curve was shown, and the calculate expression of shear strength used by stress path under random consolidation degree. In addition, the new double hardening model and the concept of dynamic shape function were proposed, the formulae for the explicit finite element method to analyze Biot dynamic consolidation equation. The procedure of single-point and single-time tamping was simulated by using of the finite element program DCFEM which considerations in axisymmetric problems. The computation results shown that the stress wave was transmit in ground according to erect elliptical spherical surface. The consistency among the computation results, laboratory test results and the date measured in site was obtained.Finally, the achievements of this thesis are summarized, and the mechanism and technical process of silty soft clay under dynamic consolidation by drainage are obtained from the laboratory tests result.
Keywords/Search Tags:the method of dynamic consolidation by drainage, saturated silty soft clay, impact loading, engineering characteristic, pore water pressure, axial deformation, shear strength, elastic-plastic model, finite element method
PDF Full Text Request
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