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Wang X.,Henan Polytechnic University | Wang X.,Institute of China Pingmei Shenma Group | Zhen X.,Henan Polytechnic University | Li R.,Shanghai Geotechnical Engineering and Geology Institute Co. | And 4 more authors.
Water Science and Technology | Year: 2016

This paper mainly studied migration and transformation characteristics of dissolved organic matter (DOM) in underground aquifers. To achieve the research purpose, we carried out the dynamic column experiments of the DOM at different conditions indoors. In the experiment, the water of Wujiang River from Pingdingshan Coal-field is used as water sample, meanwhile, fine sand and marl rock are used as testing rock sample. A comparative study on migration and transformation characteristics of the DOM in different rock samples is done. The results show that, in the fine sand, the main effects are convection and dispersion, while the adsorption and biological effects are very weak. However, in the marl rock, besides existing convection and dispersion, the adsorption and biological effect are quite significant. And in the marl rock, convection and dispersion plays a major role in the early experiment, while adsorption is the main effect in the medium term, then the biodegradation dominates the final stage. With the increasing of temperature and seepage velocity in the fine sand, the impact of the convection effect becomes gradually weak, the dispersion effect gradually enhances, and, however, convection effect is still playing a dominant role. With the temperature rising in the marl rock, the adsorption effect becomes weak, but biodegradation is enhanced. As the seepage velocity increases in the marl rock, the adsorption and biodegradation both decrease. © IWA Publishing 2016 Water Science & Technology.

Wang X.,Henan Polytechnic University | Wang X.,The Central Plains Economic Zone Shale of Coal Seam Gas Collaborative Innovation Center in Henan Province | Wang T.,Henan Polytechnic University | Wang Q.,University of Chinese Academy of Sciences | And 3 more authors.
Mine Water and the Environment | Year: 2016

A new evaluation model, based on fractal theory and an improved analytic hierarchy process (IAHP), was developed to predict the potential for water inrush. Fractal theory was used to quantitatively evaluate the complexity of the fault zones, which is a major water inrush factor. Study of the Lu-an mining area showed that the faults there can be subdivided into four levels of complexity: simple, medium, relatively complex, and complex. The overall complexity of the fault network in the study area was moderate. The IAHP was used to study the potential for coal floor water inrush through these faults. The results indicated that this mining district can be divided into risk-based zones. The extremely high risk zones were mainly located in the northern Tun-liu mine and the northern Chang-cun mine; high risk zones were primarily distributed in the Tun-liu mine and the southwestern Wang-zhuang mine. All other mines were classified as medium and low risk zones. © 2016 Springer-Verlag Berlin Heidelberg

Yang Y.,Jilin University | Sun Y.,Jilin University | Guo W.,Jilin University | Xu H.,Jilin University | Feng X.,Shanghai Geotechnical Engineering and Geology Institute Co.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2012

In order to solve the encountered leakage problems in the process of gas hydrate exploration, the low-temperature fluid formulation should be designed to ensure good rheological properties and dehydration characteristics, with better Collapse prevention capability at the same time. The performance of different polymer drilling fluid formulations at room temperature and low temperature conditions were tested. The effect of molecular structure, functional groups and the main-chain form on the polymer drilling fluid properties were analyzed. The type and quantity of functional groups is the key element to affect inhibiting ability of drilling fluid, and -OH, -CONH2 and -COONa can form adsorption film rapidly to inhibit clay dispersion. And the greater polymerization degree of polymer, the smaller the leakoff amount of drilling fluid, which has little concern with the molecular structure. It explains the role law and impact level of polymer to drilling fluid from the microscopic point of view, providing a theoretical basis for the selection and the scaling of the drilling fluid formulation materials under different conditions. The formula is determined after testing and theoretical analysis: Bentonite(1.5%) + PVA(1.875%~2.250%) + PHPA(0.250%~0.313%) + ETH(15%~20%) + NaCl(7.5%). This formula has been used for the China Geological Survey Mohe Basin gas hydrate Scientific Drilling Project, which showed the good rheological properties and Collapse prevention capability, and laid the foundation for obtaining gas hydrate samples successfully.

Gu C.,Hohai University | Chen Y.,Yellow River Institute of Hydraulic Research | Chen H.,Shanghai Geotechnical Engineering and Geology Institute Co. | Qu X.,Hohai University
Geotechnical Special Publication | Year: 2011

Because of the complexity of pile-soil interaction under the effect of horizontal load, the calculation theory and method for horizontal bearing pile are not perfect, so further study shall be conducted. Based on the basic field test of long elastic pile in a port project, the construction effect of cement injection pile has been evaluated according to the testing results in this paper. ABAQUS has been used for three-dimensional simulation calculation of the single pile in the testing area; smeared cracking model has been used for simulating the endurance of concrete; embedded element has been used to simulate the reinforcement bar in concrete. The inner force distribution in every elevation of pile has been calculated, and then compared with testing value and the results suggest that the precision of numerical calculation can meet the engineering requirements. © 2011 ASCE.

Gu C.-C.,Hohai University | Chen H.-S.,Shanghai Geotechnical Engineering and Geology Institute Co. | Sun Y.-K.,Hohai University
Geotechnical Special Publication | Year: 2011

Based on the load transfer mechanism about the bi-level model, this paper studies on the influence about frictional force in side-pile of cement soil plug which pre-stressed pipe pile is implanted into a large diameter bidirectional cement mixing pile in a concentric manner. On the basis of the analysis of soil-compacting direction, theory of cavity expansion has been adopted to analyze the disturbance on the side soil in the pile driving process of pre-stressed pipe pile in MPSC. According to the lower core pile, the radial stress of pile-soil contact surface before and after the complete occlusion of cement soil plug is calculated combining the shear strength of foundation soil after disturbance. The eigenvalues of lateral friction before and after complete occlusion of soil plug are adopted according to comparison between the length of soil plug and outer pile. Considering extruding densification of core pile, improvement coefficient is implied in modifying the ground soil and outer pile, the calculation Equation for lateral friction of MPSC has been developed. © 2011 ASCE.

Shao C.,Shanghai Geotechnical Engineering and Geology Institute Co. | Yue F.,China University of Mining and Technology | Zhang Y.,China University of Mining and Technology | Shi R.,China University of Mining and Technology
Modern Tunnelling Technology | Year: 2013

The mechanical behavior parameters of frozen soil are an important reference for engineering design and construction. To ensure the security and rationality of construction, some tests were carried out concerning the uniaxial unconfined compression strength, bending strength, failure deflection, freezing temperature, frost heave ratio, and thaw settlement coefficient of frozen soils using the example of a connection passage of the Guangzhou metro line 6. The results show that: uniaxial unconfined compressive strength of various soil layers is greatly improved at -10°C compared with that at a natural state, reaching 6.43~9.48MPa; the bending strength is between 2.97MPa and 5.67MPa; the failure strain and the failure defection meet the construction requirements; the frozen temperature is between -0.5°C and 0.6°C; the frost heave ratio is 10.79%-12.44%; and the thaw settlement coefficient is 11.06%~13.48%.

Gao G.-Y.,Tongji University | Chai J.-L.,CREEC East China Survey and Design Co. | Zhang X.-L.,Shanghai Municipal Bureau of Planning and Land Resources | Jin Q.-S.,Shanghai Geotechnical Engineering and Geology Institute Co.
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

Considering the existing calculation methods' shortcomings of water gushing in foundation pit. The strain dependent modified Cam-clay (SDMCC) model adopted to model the soil behavior and confined water was taken into account in the finite difference model by FLAC 3D. With the increase of the confined water head (H w), the foundation pit heave was divided into three stages: slow uniform deformation, accelerating deformation and sharp uniform deformation. A new method for determining critical water head (H wcr) of water gushing in foundation pit was presented based on numerical analysis; and the calculation result of the new method was compared with other methods.

Gao G.,Tongji University | Wu Y.,Tongji University | Zhang X.,Shanghai Municipal Bureau of Planning and Land Resources | Jin Q.,Shanghai Geotechnical Engineering and Geology Institute Co. | Feng S.,Tongji University
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2011

Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) was employed to simulate stage-excavated and supported foundation pit. According to different locations between tunnel and excavation, two types-'closed-type' and 'shallow-embedded-type' and seven conditions can be categorized regarding the analysis of the interaction between deep excavation and the adjacent existing tunnel. Modified Cambridge model was adopted to model the soil behavior. And the interaction between soils and retaining structures was also taken into account in the numerical analysis. The result shows that the deformation of the tunnel is incompletely monotony with the distance from the excavation, and the presence of the tunnel imposes a 'reinforcement effect' on the soil mass behind the retaining wall.

Guan F.,Shanghai Geotechnical Engineering and Geology Institute Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

For the optimization design it is crucial to comprehensively study geotechnical investigation reports, geometric parameters of excavations, protection requirements of surrounding environment budget and time limit for the project. In this case, the composite soil-nailing wall is adopted to stabilize the shallow soil layers so that the floor numbers of bracing system can be reduced to only one considering the hardpan under soft soil. Circular reinforced concrete bracings which can form open construction space and cast-in place piles are used together to constitute the retaining structure system. The deformation and stability of the excavation are analyzed by adopting Tongji Qistar and Plaxis 2D. The monitoring work is carried out during the whole construction process. The rationality and effectiveness of the optimized scheme are tested by the results of the analysis and the monitoring data and can be used for similar projects.

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