Entity

Time filter

Source Type


Chen X.,Hohai University | Chen X.,Bureau of Mineral Resources | Luo Z.,Hohai University | Jin W.,Hohai University | Tan J.,Jiangsu Nanjing Institute of Geo engineering Investigation
Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering | Year: 2015

Aiming at the land subsidence problems additively effected by both groundwater exploitation and high-rise building load with the increase of high-rise buildings in the process of urbanization, based on the Biot's consolidation theory and combined with the nonlinear rheological theory of soil, the constitutive relation in Biot's consolidation theory was extended to viscoelastic plasticity, and the dynamic change relationships between the porosity, hydraulic conductivity, soil deformation parameters and effective stress were also considered, a finite element numerical model for high-rise building load, groundwater seepage and land subsidence were established. Land subsidence characteristics under the condition of both groundwater exploitation and high-rise building load were thoroughly studied. It shows that land subsidence additively effected by both groundwater exploitation and high-rise building load exists coupling effect. Land subsidence under the condition of both groundwater exploitation and high-rise building load is lower than the sum subsidence in two separate cases. In addition, the deeper buried depth of groundwater exploitation layer is, the weeker coupling effect is. Linear additive effect is obvious at the first stage of subsidence. Coupling effect is tending towards stability with time prolonged. ©, 2015, The Editorial Board of Journal of Basic Science and Engineering. All right reserved. Source


Jin W.,Hohai University | Luo Z.,Hohai University | Chen X.,Hohai University | Tan J.,Jiangsu Nanjing Institute of Geo engineering Investigation
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2014

In order to accurately simulate land subsidence caused by seepage field as a result of groundwater exploitation and stress field, two models are established in this study: one is groundwater seepage and land subsidence coupling numerical simulation model of the three-dimensional seepage of groundwater and one-dimensional vertical consolidation in light of Terzaghi effective stress principle; and the other is three-dimensional coupling model of groundwater seepage and land subsidence based on the Biot's consolidation theory combined with the nonlinear rheological theory of soil, extending the constitutive relation in Biot's consolidation theory to viscoelastic plasticity, taking into consideration of the dynamic change relationship of mechanical parameters and hydraulic parameters. The comparison and analysis show that the changing tendency of land subsidence calculated by groundwater seepage and land subsidence coupling numerical simulation model of the three-dimensional seepage of groundwater and one-dimensional vertical consolidation is the same as that of water level variation. When the water level falls back to the initial water level, total subsidence is 0. Land subsidence calculated by Biot's three-dimensional full coupling model falls behind of water level change. When the water level falls back to the initial water level, soil does not rebound to initial 0 subsidence state. There exists permanent remain of subsidence. In aspect of parameter change, porosity, hydraulic conductivity and Poisson's ratio have the tendency of decreasing first and then increasing. Modulus of elasticity has the tendency of decreasing first and then increasing. But these parameter values tend to be stable, corresponding to land subsidence variation. Source


Luo Z.,Hohai University | Jin P.,Hohai University | Tian K.,Jiangsu Nanjing Institute of Geo engineering Investigation | Tan J.,Jiangsu Nanjing Institute of Geo engineering Investigation
Jiangsu Daxue Xuebao (Ziran Kexue Ban)/Journal of Jiangsu University (Natural Science Edition) | Year: 2016

Based on Terzaghi consolidation theory, a three dimensional full coupling model between deep foundation pit dewatering and land subsidence was established. The computer program of calculating process was compiled by FORTRAN95 language, and the visualization operational software was established by VB 6.0 to predict and simulate deep foundation pit dewatering and land subsidence. With graphical interface mode, the relationship between deep foundation pit dewatering and land subsidence was simulated and expressed to propose an optimal plan of dewatering. Taking deep foundation pit dewatering of Liuzhou East Road Station of Nanjing Metro Line3 as example, the software was used to simulate the deep foundation pit dewatering. The results show that an optimal project is obtained by adopting 15 dewatering wells for 10 days, and the water table of pit is maintained 1.0 m below the floor with depth of 20.8 m. After 66 days later, the land subsidence is less than 0.015 m at 100.0 m away from the pit, which meets the control requirements of settlement. © 2016, Editorial Department of Journal of Jiangsu University. All right reserved. Source


Fu Y.,Hohai University | Jin W.,Hohai University | Chen X.,Hohai University | Chen X.,Bureau of Mineral Resources | Tan J.,Jiangsu Nanjing Institute of Geo engineering Investigation
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2014

Aiming at soil deformation caused by high-rise building load in the region where groundwater buried depth is more shallow, based on the Biot's consolidation theory and combined with the nonlinear rheological theory of soil, the constitutive relation of soil was extended to viscoelastic plasticity, and the dynamic change relationship of mechanics parameters and hydraulic parameters with pore water pressure was also considered, a three dimensional finite element numerical model of land subsidence and upheaval deformation caused by high-rise building load was established. The characteristics of soil deformation that was affected by high-rise building load and variation characteristics of soil mechanics parameters and hydraulic parameters in this process were studied and analyzed in detail. It is shown that land subsidence caused by high-rise building load is funnel-shaped and the funnel center is high-rise building center. At the early stage of application of high-rise building load, land upheaval appears around building, and land upheaval disappears gradually after land upheaval reached the maximum value. The change trend of porosity, hydraulic conductivity and Poisson's ratio of shallow soil under high-rise building performs an evolution of decreasing. But the change trend of modulus of elasticity performs an evolution of increasing. Porosity, hydraulic conductivity and Poisson's ratio of shallow soil around high-rise building performs the tendency of increasing firstly and then decreasing. Modulus of elasticity performs the tendency of decreasing firstly and then increasing. The change trend of shallow soil parameters around the high-rise building is related to the upheaval and the compression of soil. Source


Chen X.,Hohai University | Chen X.,Bureau of Mineral Resources | Luo Z.,Hohai University | An X.,Hohai University | And 2 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2013

In order to accurately predict the dynamic characters of groundwater seepage field and land subsidence caused by dewatering of deep foundation pit in loose sediments, a ground settlement coupling model was established in this study. In this coupling model, three dimensional variable-parametric non-steady seepage of precipitation of deep foundation pit and one-dimensional consolidation theory based on Terzaghi were used. The porosity, permeability coefficient and water storage dynamic changes with the decline of groundwater level were also considered. And a three dimensional fem numerical method was applied to solve the model. The dewatering of the deep foundation pit in Puzhu Rd station, metro line 3, in Nanjing was taken as a case study. The results showed that an optimal project was obtained by adopting 15 dewatering wells for the pit, locating the filters of the pumping wells at depth of 22.0-37.0 m and defining a pit's diaphragm wall at a depth of 41.5 m. By using this project, groundwater level could meet the excavation requirements and surface settlement outside the pit could also be within the controlled limits. The coupling model proposed was proven reasonable and reliable. And it has more credibility to use the theories in the article to simulate and predict the groundwater flow in deep foundation pit dewatering in similar areas. Source

Discover hidden collaborations