Wuhan, China
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Peng J.,WuhanUniversity | Rong G.,Lawrence Berkeley National Laboratory | Cai M.,Laurentian University | Du W.,Changjiang Project Supervision and Consultant Company
47th US Rock Mechanics / Geomechanics Symposium 2013 | Year: 2013

Mohr-Coulomb and Hoek-Brown failure criteria are the two most widely used failure criteria in rock engineering. To simulate brittle failure of rocks in deep tunnel, models based on these two failure criteria have been proposed, including the Cohesion Weakening and Friction Strengthening (CWFS) model, the Damage Initiation and Spalling Limit (DISL) model and the Brittle-Ductile- Plastic (BDP) model. However, because of the issues of strain hardening under high confinement and large ambiguity in model parameter determination, these models face limitations in practical engineering application. Based on progressive failure of rocks, we found that cracks propagate under compression and as a result the Geological Strength Index (GSI) decreases with the increase of plastic strain. By defining the GSI value as a function of plastic strain, a strain-dependent GSI-softening model based on the Hoek-Brown failure criterion is proposed. This model is then implemented in FLAC3D to simulate the triaxial compression test of T2b marble in Jinping-II hydropower station. It is found that this model is able to simulate the mechanical behavior of the brittle-ductile transition observed in the triaxial compression test of the Jinping marble. Copyright 2013 ARMA, American Rock Mechanics Association.

Yan T.,WuhanUniversity | Chen L.,WuhanUniversity | Xu M.,WuhanUniversity | Ping Y.,WuhanUniversity
Journal of Hohai University | Year: 2015

Tianjin Research Institute for Water Transport Engineering, Ministry of Transport, Tianjin 300456 This study investigated the change hydrodynamic characteristics at the confluence reach in BaiShi Reservoir area in the Daling River with different factors, based on model testing. The results show that the water depth and flow area increase along the channel, and the flow velocity in the mainstream and tributaries upstream of the confluence zone increases along the channel as well, while the flow velocity downstream of the confluence zone decreases significantly along the channel. The backflow region occurs in the tributaries downstream of the confluence zone, and its range increases with the confluence ratio. When the water level upstream of the dam increases, the absolute value of the velocity and its change rate along the channel decrease in the confluence zone, while the degree of curvature of the main stream line and the backflow region range increase. ©, 2015, Editorial Office of Journal of Hohai University (Nature Sciences). All right reserved.

Qin J.,WuhanUniversity | Jie Q.,WuhanUniversity | Fan Z.,WuhanUniversity
European Physical Journal B | Year: 2014

We present an efficient implementation of the hierarchical mean-field theory with largeblock in quantum spin systems. The wave function is a product of the large block states.Each large block state is a superposition of products of small block states. Our result isvery close to that of the hierarchical mean-field in a numerical cost effective way. Wetest our method on a frustrated spin lattice. © 2014, EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

PubMed | WuhanUniversity
Type: Journal Article | Journal: IEEE transactions on neural networks | Year: 2011

This paper presents a novel dynamic channel assignment (DCA) technique for large-scale cellular networks (LCNs) using noisy chaotic neural network. In this technique, an LCN is first decomposed into many subnets, which are designated as decomposed cellular subnets (DCSs). The DCA process is independently performed in every subnet to alleviate the signaling overheads and to apportion the DCA computational load among the subnets. Then a novel energy function is formulated to avoid causing mutual interference among neighboring subnets based on the real-time interference channel table. In each subnet, the proposed energy function also satisfies three interference constraints among cells and the number of required channels of each cell, and simultaneously minimizes the total number of assigned channels to improve spectrum utilization. A typical 441-cell LCN with 70 available channels, which can be decomposed into nine 49-cell DCSs, is examined to demonstrate the validity of the proposed technique by blocking probability, including uniform and hot spot traffic patterns.

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