1 College of Geographic Science, Henan Key Laboratory for Synergistic Prevention of Water and Soil Environmental Pollution, Southern Henan Center for Mineral Rock and Gem-Jade Identification and Processing, Xinyang Normal University, Xinyang 464000, China 2 Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring (Central South University), Ministry of Education, Changsha 410083, China 3 Hunan Geology Exploration Institute of China Chemical Geology and Mine Bureau, Changsha 410004, China 4 Hunan Key Laboratory of Land Resources Evaluation and Utilization, Changsha 410007, China 5 Institute of Resources and Environmental Engineering, Guizhou University of Technology, Guiyang 550003, China

/pdf/metallogenic-fluid-characteristics-of-yueshan-cu-2kv60ab4l9.pdf

Metallogenic Fluid Characteristics of Yueshan Cu-polymetallic Deposit

Received: 15 November 2018 Accepted: 2 March 2019 Our research targets a subway foundation pit construction project in Nanning, a city in southwestern China. The foundation pit was excavated in the water-rich round gravel stratum. The theoretical calculation was combined with finite-element analysis, which is based on drag coefficient method, to derive the relevant seepage parameters of the stratum. The complex seepage surface was solved through the meshing of virtual grids with fixed nodes. The 3D seepage field around the ground-connecting wall in the pit (hereinafter referred to as the wall) was investigated through finite-element analysis on midas GTS NX. In this way, the author identified the features and law of soil seepage around the wall in the water-rich gravel stratum. The results show that the middle and lower part of the wall were within the sand layer and the gravel layer, both of which are strongly permeable; the seepage rate around the wall peaked in the middle of the wall (0.156 m/sec); there was an obvious seepage effect in the pit; the waterrich gravel stratum had greater seepage water inflow than any other stratum; the pore water migration features could be described accurately by the seepage control equation of the heterogeneous anisotropic porous medium.

/pdf/3d-finite-element-analysis-of-soil-seepage-in-water-rich-1nownnvufk.pdf

3D Finite-element Analysis of Soil Seepage in Water-rich Gravel Stratum

Concentration technique via progressive freeze concentration was applied to increase the concentration of coconut water for commercialisation. The process will eliminate portion of water from coconut water and retain pure nutritional compound with high sugar content. To obtain the optimum condition, which is the objective of this study, optimisation process was conducted using Response Surface Methodology (RSM) through STATISTICA Software. RSM was utilised to optimise the process parameters for effective partition constant(K) in progressive freeze concentration (PFC) of the coconut water. The effects of circulation flowrate, circulation time, initial solution concentration and coolant temperature on effective partition constant were observed. Results show that the data adequately fit the second-order polynomial model. The linear and quadratic independent variables, circulation flowrate, circulation time, initial concentration and coolant temperature have significant effects as well as interactions on the effective partition constant. It was observed that the optimum process parameters within the experimental range for the best K would be with circulation flowrate of 3,400 mL/min, circulation time of 23 min, initial concentration of 3.4 % Brix and coolant temperature of -7 °C. Under these conditions, the K can be enhanced up to 0.3.

Process Optimisation of Effective Partition Constant in Coconut Water via Progressive Freeze Concentration

Broken freezing tubes caused by frost-heave stress are often found in freezing construction of thick overburden.In order to reduce the internal heave stress produced in the forming process of deep shaft' freezing wall,the research adopts such a construction plan,in which the addendum circle assistance hole freezing lags behind the host circle hole freezing,which can prevent the freezing tube from break effectively.Finite element method for the freezing process was applied to simulate the transient state temperature fields of a coal mine in Huainan,of which the host well tube was frozen by stages.The simulated results are extremely close to the observed ones.To freeze by stages is able to decrease water aggregation within the frozen wall and reduce frost-heave stress,and then a relative uniform temperature field is formed.Under the same freezing condition to freeze by stages may cause frozen wall's effective thickness about 15% thicker.System analysis of the numerical simulation may provide a scientific basis for design and construction of a deep-well's frozen wall.

Observation and Analysis of the Temperature Field of Host Well Tube Frozen by Stages

Received: 8 January 2018 Accepted: 10 May 2018 This paper attempts to disclose the distribution law of artificial freezing temperature field in Cretaceous sandstone of western China and determine the key parameters of freeze sinking. For this purpose, a numerical model was established in light of the general conditions of freeze sinking project, the model parameters were optimized according to onsite monitored data, and the optimized model was applied to explore the change law of the freezing temperature field. The simulation reveals that the temperature of each measuring point decreased linearly with time, but the mean daily decline differed from point to point: the daily decline is negatively correlated to the distance from the freezing point, i.e. the temperature is positively correlated to the distance from the freezing point at the same time. The freezing time for closure was 79d at the groundwater flow rate of 50m/d. When the freezing intensity was weak (freezing tube temperature: -22°C), the frozen wall failed to achieve closure. This means the groundwater directly bears on the distribution of the temperature field. The freezing intensity has a nonlinear impact on the temperature field. The higher the temperature, the smaller the impact on the closure.

/pdf/temperature-field-distribution-of-a-freeze-sinking-shaft-4kdmwzfzfu.pdf

Gengshe Yang

Papers

Temperature field distribution of a freeze sinking shaft under seepage conditions in cretaceous formation of Western China