Hydrogeochemical Processes and Inverse Modeling for a Multilayer Aquifer System in the Yuaner Coal Mine,Huaibei Coalfield,China

Coal mining can dramatically change hydrogeological conditions and induce serious environmental problems. Fifty groundwater samples were collected from the main aquifers in the Yuaner coal mine (Anhui Province, China). The results show that the main hydrogeochemical processes in the mine include dissolution, precipitation, pyrite oxidation, desulfurization, and cation exchange. The Neogene porous aquifer is affected by groundwater flow conditions; its main hydrogeochemical processes are dissolution of carbonate minerals and gypsum, and cation exchange. The Permian coal measure’s fractured sandstone aquifer was confirmed to be controlled by the region’s geological structure; its main hydrogeochemical processes are desulfurization and cation exchange. The Carboniferous Taiyuan limestone aquifer was determined by both groundwater flow conditions and regional geological structure; its main hydrogeochemical processes are dissolution of carbonate minerals and gypsum, pyrite oxidation, and cation exchange. Additionally, hydrogeochemical inverse modeling of the groundwater flow path confirm the hydrochemistry results and principal component analysis.

     

连拱隧道浅埋偏压段的受力和变形机制研究

 以安景高速双河口隧道为工程背景,针对连拱隧道洞口浅埋偏压段特殊的地形情况,探讨围岩在地应力和边坡滑动共同影响下的应力分布情况。为满足工程应用的需要,在监测数据分析的问题上提出对监测数据进行非线性分离的方法,并以其中的线性趋势项为依据建立围岩的应力与变形之间的映射关系,来指导隧道设计和施工,用分离出来的波动项来分析施工过程中出现的异常情况。结果表明：连拱隧道洞口浅埋偏压段受到上覆荷载和边坡滑动的共同作用,其中最危滑动面和洞口上部坡角处的围岩和支护结构受边坡滑动的剪拉作用影响最为明显,消除施工等因素影响的监测数据趋势项可以更直观地说明这一点,因此在隧道工程中如果穿越岩体最危滑动面附近的围岩时有必要考虑边坡滑动的影响。     

Prediction of Water Inrush Areas Under an Unconsolidated,Confined Aquifer: The Application of Multi-information Superposition Based on GIS and AHP in the Qidong Coal Mine,China

The complex geological and hydrogological conditions under the unconsolidated and confined aquifer in the Qidong coal mine have resulted in serious water-inrush hazards. Multi-information superposition was used to predict water inrush areas. Six controlling factors (the specific yield, the effective thickness and load transfer coefficient of the aquifer, the fractal dimensional value of bedrock faults, the effective thickness of the protective bedrock layer, and the distance between the key hard stratum and the primary mineable coal seam) were selected, and a multi-information superposition model was established. Relatively safe areas and medium and higher risk areas were identified using a geographic information system (GIS) and the analytic hierarchy process (AHP). Using the no. 7₁ primary coal seam in the northern portion of the Qidong mine as an example, the water-inrush areas predicted by the model aligned with observed conditions, which validates the multi-information superposition model. Potential inrush areas of the no. 6₁, 8₂, and 9 primary coal seams in the southern portion of the Qidong mine were subsequently identified using this method, which will aid future mining operation.     

深厚表土段井壁径向荷载的规范计算方法探讨

针对我国立井井筒设计规范建议的径向荷载计算方法的准确性与适用性问题,基于多个立井工程的地质资料及参数,根据规范方法计算得到其径向荷载的理论分布特征,并与实测数据进行了比较。结果表明,规范建议公式的计算结果与实测值存在一定的误差,尤其是计算岩层中的井壁径向荷载误差较大,且立井深度越大,基于规范算法得到的井壁径向荷载误差越大。由此建议深入开展深土力学研究,基于更多的测试与研究来确定深厚表土中井壁径向荷载的大小与分布规律。     

釜式固定管板式换热器折流板位置的改进

在设计釜式固定管板式换热器时,应将最后装配的那块折流板放在变径段的小端筒体上,这对换热管较长的该类设备尤为必要。     

Novel and simple methodology to fabricate porous and buckled fibrous structures for biomedical applications

Reproducible buckled and porous sub-micron diameter polycaprolactone (PCL) fibers were produced by simple electrospinning process for biomedical applications. In this study, six types of solvent combinations with different vapor pressures were used to study the effect of phase separation on the morphology of electrospun fibers. The fiber morphology, Infrared spectroscopy, water contact angle and tensile test were performed to study the material properties. It is evident that the fiber morphology was affected by solvent combinations used for the fabrication of sub-micron fibers. The solution viscosity, the collecting distance and the type of solvent combination used could be an optimum parameter for the generation of porous-buckled fibers with narrow pore size distribution. The simplicity of the set-up is the immense advantage for producing buckled and porous elastomeric fibers for tissue engineering applications. All the fibers were spun on a motionless collector plate to study the properties of fibers. The combination of surface pores with the buckled pattern could be of great importance in the field of biomedical engineering.     

坚硬脆性岩体中圆形洞室岩爆破坏的平面应变模型试验研究

为了探讨圆形地下洞室围岩岩爆破坏过程与机制,以单轴抗压强度(σc)、脆性系数(K)与冲击能量指数(WB)为概化指标,通过物理模型材料的正交试验,选取合适的具有岩爆倾向性的坚硬脆性岩体物理模型材料,制作了尺寸为800mm×800mm×200mm(长×宽×厚)、中心为φ160mm的圆形洞室物理模型试件,并在岩土工程大型真三轴物理模型试验机上进行平面应变物理模型试验。试验结果表明:在保持物理模型试件水平荷载与垂直荷载相等并同步提高过程中,围岩由弹性状态进入塑性状态,σθ-(r/r0)曲线表现峰值后移,σr-(r/r0)曲线形状变化不明显。当对物理模型试件同步施加水平荷载Ph与垂直荷载Pv均为600kN时,洞壁出现葱皮状剥落。同步施加水平荷载Ph与垂直荷载Pv均为630kN时,围岩在极短的时间与极窄的加载区间内围绕洞壁出现大规模突发性破坏,继续同步施加Ph与Pv,在相对较长时间与荷载区间内,围岩应力调整,出现相对稳定期。     

坚硬岩体中马蹄形洞室岩爆破坏平面应变模型试验

为了探讨马蹄形地下洞室围岩岩爆破坏过程与机理,以单轴抗压强度(σc)、脆性系数(K)与冲击能量指数(WB)为概化指标,通过物理模型材料的正交试验,选取了合适的具有岩爆倾向性的坚硬脆性岩体物理模型材料,制作了长800 mm×宽800 mm×厚200 mm的马蹄形洞室物理模型试件,并在岩土工程大型真三轴物理模型试验机上进行高应力条件下平面应变物理模型试验。试验结果表明:在高地应力条件下,马蹄形洞室坚硬脆性围岩岩爆破坏主要在洞壁围岩初始破坏裂纹产生后,在极短的时间与极窄的加载区间产生的破坏,破坏具有突发性;洞室围岩在发生岩爆破坏后,围岩应力要进行重新调整,在相对较长时间与加荷区间内围岩表现相对稳定。岩爆破坏过程的物理模拟结果与工程实际基本一致。     

Hydrogeochemical Processes of Carboniferous Limestone Groundwater in the Yangzhuang Coal Mine,Huaibei Coalfield,China

We examined the primary mechanisms controlling water quality evolution in the Carboniferous aquifer in the Yangzhuang coal mine (Huaibei coalfield). Q-mode factor analysis explained how the Na⁺ and SO₄^2? concentrations gradually increase and the hydrochemical type transforms from Ca-HCO₃ to Ca·Na-HCO₃ and Ca·Na-HCO₃·SO₄ along the flow path. The high bicarbonate concentration appears to be due to dissolution of calcite and dolomite and an open carbonate system, while frequent water inrushes and the declining water level provide evidence for the relative closure of the Carboniferous limestone aquifer. Gypsum dissolution is the main SO₄^2? source. Inverse geochemical modeling sufficiently explained the hydrogeochemical processes that control the water quality evolution. These findings should aid the interpretation of groundwater hydrochemical evolution and groundwater quality management in the study area and other north China coalfields.

     

水位变化对非均质库岸边坡稳定性的影响

在假定坡体内孔隙水水位为水平线且不考虑渗透作用影响的基础上,利用极限平衡法基于简化计算模型考察了库水位上升及下降的快慢对非均质库岸边坡稳定性的影响。对比计算表明:在库水位骤降或陡升的情况下,相同库水位对应的边坡安全系数基本上均小于水位缓慢变化情况下的安全系数。故工程实际中无论是排水还是蓄水,都应尽量保持库水位缓慢变化,这样才能尽量使库岸边坡处于相对较安全的状态。