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Hu Y.-J.,Zhejiang University | He C.-L.,Zhejiang University | Zhu X.-B.,Qiantang River Administration of Zhejiang Province | Wang G.-Q.,Qiantang River Administration of Zhejiang Province
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2011

In order to clarify the influences of different conditions on the seawall seepage deformation and to formulate rational and effective impervious reinforcement scenario, combined with the problems encountered in the impervious reinforcement of Qiantang River seawall, this work applied the saturated-unsaturated and unsteady seepage flow analysis program considering the soil permeability variation with seepage deformation propagation to analyze the effects of the initial phreatic line, initial water content of soil, rainfall and flood characteristics on the seawall seepage deformation. The analysis results show that the initial phreatic line plays a constraint role to the seawall seepage deformation; the increase of initial soil saturation will shorten the penetration time required for back slope; under the flood with rain, the phreatic line of seawall will rise up fast and can produce large seepage gradient of back slope; the closer rainfall will produce the larger influence; the water level and waveform of flood are also have great influence on the penetration process of seawall.

Wang L.-Z.,Zhejiang University | Jiang H.-Y.,Zhejiang University | Yang Z.-X.,Zhejiang University | Xu Y.-C.,Qiantang River Administration of Zhejiang Province | Zhu X.-B.,Qiantang River Administration of Zhejiang Province
Computers and Geotechnics | Year: 2013

Discontinuous deformation analysis (DDA) has been widely applied in simulations of discontinuous blocky systems. The behavior of a discontinuous blocky system is mainly governed by the strength of the interface joints. The Mohr-Coulomb joint failure criterion, adopted in the original DDA, is examined through a classic case of a single block on an inclined plane. It shows that when interface cohesion exists, the block may be unstable even if the interface strength is greater than the theoretical strength required for critical stability, as the cohesion has been improperly removed. Adopting relative displacement between contacted blocks as the criterion for the removal of cohesion will provide more accurate results. The development of DDA with displacement-dependent interface shear strength is presented in this paper. To implement and illustrate the modified algorithm, two examples of progressive landslide failure simulations are performed. Both systems exhibit a two-stage failure pattern: a relatively slow, downward progressive failure stage followed by a rapid, massive run out failure stage. © 2012.

Han Z.,Zhejiang Institute of Hydraulics and Estuary | Tang Z.,Zhejiang Institute of Hydraulics and Estuary | You A.,Zhejiang Institute of Hydraulics and Estuary | Cao Y.,Zhejiang Institute of Hydraulics and Estuary | Xing Y.,Qiantang River Administration of Zhejiang Province
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2015

By the definition of bed forming discharge, sediment transports during flood tide and ebb tide of various tidal frequencies were calculated for a tidal estuary. The results show that the bed forming effects are the strongest at annual average runoff combined with mean ebb tide, so the bed forming discharge of this estuary should be the ebb-tide discharge. Tidal estuaries can be categorized as two types, namely general estuary and tidal bore estuary. The former's characteristics of cross section depends on average ebb-tide discharge and average sediment concentration, while for the latter, its width of cross section depends on average flood-tide discharge, and its corresponding depth, longitudinal widening rate and bed slope of river channel are determined by both flood-tide and ebb-tide discharges and sediment concentration. This paper formulates a series of empirical relationships between hydrodynamics and morphology for macro-tide estuaries. Using the measured cross-sectional bed profiles of five estuaries in Zhejiang province, we have verified these formulas of river regime, including cross-sectional area, width and depth, width-depth ratio, widening rate, expanding rate of cross-section area, river bed slope, etc. Their average calculation errors are less than 10%, and the calculations with errors exceeding 90% are less than 20%. The formulas, through certain conversion, show that the cross sections below half-tide levels correspond to the ones for sediment recipient motions. ©, 2015, Tsinghua University Press. All right reserved.

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