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Xiong C.,Tianjin University | Xiao M.,Shanghai Guanglian Construction Development CO.
Applied Mechanics and Materials | Year: 2012

The pumping tests on the hydrogeology, including single well tests, group wells tests and land subsidence analysis, were carried out for Tianjin transportation center project. The straight-line graphical method, curve fitting method, formula method and infiltration curve extrapolation method were applied to obtain the permeability coefficients and influence radius of the main aquifers, and to obtain the mutual influence between the aquifers. The results of the land subsidence observations indicate that amount of land subsidence decreases with increasing distance from the wells. And it is also found the land subsidence of a band range is obvious, and its distribution changes unregulated. It could be preliminarily inferred that this anomaly is due to the venue internal west alkali river that has been recently backfilled. © (2012) Trans Tech Publications, Switzerland.

Zheng G.,Tianjin University | Zeng C.-F.,Tianjin University | Liu C.,Tianjin University | Shi X.-R.,Shanghai Guanglian Construction Development Co. | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

By carrying out in-situ pumping tests in an excavation of Tianjin, hydraulic connection between the first and second confined aquifers is observed. Because the second confined aquifer isn't cut off by waterproof curtain, to reduce or eliminate the settlement of the key protected buildings induced by dewatering, the artificial recharge is applied during the process of excavation and dewatering in the pit. Five recharge wells are arranged around the protected buildings to recharge the confined aquifer using the urban water. The in-situ monitoring results show that the water volume recharged by a single recharge well can reach 24 m3/d to 72 m3/d and the water head can be raised as much as 6 m. The measured settlement of the buildings during excavation further shows that the variation of the settlement of the protected buildings almost simultaneously and directly relates to the fluctuation of the head of confined aquifer. It's the first successful case of recharge of confined water in an excavation in Tianjin based on settlement control.

Niu J.,Tongji University | Zhang T.,Shanghai Guanglian Construction Development Co. | He Y.,Shanghai Guanglian Construction Development Co. | Zhou H.,Shanghai Laogang Waste Treatment Company | And 2 more authors.
Journal of Hazardous Materials | Year: 2013

A pilot-scale deep shaft aeration bioreactor (DSAB) with 110m in depth and 0.5m in diameter for the pretreatment of landfill leachate in winter was operated at a daily treatment scale of around 10-20tons. It was found that the performance of the DSAB mainly depended on the inflow loads and concentrations of pollutants. NH3-N, TN, COD, TOC removals of 66-94%, 41-64%, 67-87%, 55-92% at organic load rate of 1.7-9.4g CODL-1day-1 and hydraulic retention time of 1-2d were obtained using DSAB, respectively, with the lowest ambient temperature of -3°C. The effluent COD can be reduced to below 1000mg/L, an acceptable level for advanced treatment using reverse osmosis system, when the influent COD was below 7000mg/L at 10t/d. The EEM and GPC analysis implied that the non-biodegradable contaminants such as humic- and fulvic-like DOM dominated in the organic fractions of the effluent, which rendered the biological treatment ineffective. Compared with 20-40% removals obtained using traditional biological processes below 15°C, DSAB showed a higher treatment efficiency for COD and NH3-N, even though at adverse conditions of poor carbon source, lower C/N ratio and high nitrite concentrations in the leachate of test. © 2013 Elsevier B.V.

Zhou N.-Q.,Tongji University | Tang Y.-Q.,Tongji University | Lou R.-X.,Shanghai Guanglian Construction Development Co. | Jiang S.-M.,Tongji University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

The buried depth of groundwater level is fairly shallow in Shanghai, and pit dewatering measures are mostly adopted in construction of metro stations. This study refers to the deep foundation pit dewatering project of Xujiahui Station of Shanghai Metro Line No.11. According to the site conditions of engineering geology and hydrogeology, design depth of enclosure structure and pit excavation of metro station, a numerical model of groundwater seepage is established. Through the inversion of permeability parameters based on the field pumping tests, the three-dimensional finite difference method is used to simulate the pit dewatering considering the initial and boundary conditions. The numerical results are consistent with the actual monitoring data of groundwater level. At the same time, the land subsidence induced by dewatering is calculated. The results indicate that the land subsidence around the pit can be controlled effectively.

Zhou N.,Tongji University | Zhou N.,University of Stuttgart | Vermeer P.A.,University of Stuttgart | Lou R.,Shanghai Guanglian Construction Development Co. | And 2 more authors.
Engineering Geology | Year: 2010

Shanghai is a typical area of soft soil distribution, Metro railway construction is now being developed in Shanghai City on a large scale and the planning of Metro stations are often located in densely populated districts with tall buildings. Metro station constructions are mostly taking pit dewatering measures, while the dewatering of aquifer may cause soil layer compression, land subsidence, foundation's deformation, cracking and tilting of the buildings, and so on. In order to control the land subsidence effectively, the underground continuous concrete wall is often used in the deep foundation pit dewatering. The depth of underground continuous concrete wall and the filter tube position of pumping well affect drawdown outside the pit and land subsidence directly. This study refers to the deep foundation pit dewatering project of Hangzhong Road station of Shanghai Metro Line No.10. The excavation depth of foundation pit is 15.60-17.60. m, and the design depth of underground continuous wall is 28. m in the standard part and 30 or 31. m in the end well. Three-dimensional finite differences method is used to simulate the pit dewatering through the inversion of permeability parameters based on the field pumping tests. The hydraulic barrier function of the underground continuous wall is simulated at four different depths including primary design depth, increasing 3. m, 4. m and 6. m. The result of the numerical simulation indicates that the drawdown of the aquifer decreases with the increase of the underground continuous concrete wall depth. When the underground continuous concrete wall increases 4. m on primary design basis, the drawdown outside the pit and land subsidence can be controlled effectively. The monitored results indicate that the drawdown outside the pit at a distance of 1-5. m to the wall is less than 2. m, while the maximum land subsidence is 7.97. mm, which is of nearly no influence on the environment around the pit during dewatering. © 2010 Elsevier B.V.

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