基于CFP的岩溶管道流数值模拟研究--以桂林寨底地下河子系统为例

为了描述岩溶多重含水介质存在非达西流问题,研究管道流CFP模型在岩溶区数值模拟中的应用。在分析管道流CFP基本原理的基础上,通过建立概念模型算例(5个管道,上下临界雷诺数分别为2 000和4 000),探讨不同管道水文地质参数对出口流量及水流状态的影响,并对参数敏感性进行分析,最后将CFPM1模型应用于广西寨底岩溶地下河系统,探讨在实际应用中的管道流模型适用性。概念模型结果表明,参数敏感度从大到小依次为:管道直径、水力梯度、管道渗透系数、弯曲度及粗糙度,流量与雷诺数随管道参数增大而增大,水流状态从层流变为紊流。寨底岩溶管道流模型中3个观测井及地下河出口实测流量表明CFPM1能较好地模拟出岩溶地下水水位变化趋势。得出结论:CFPM1管道流模型允许岩溶管道与基岩含水层进行水流交换,能够较好地刻画岩溶区管道介质非达西流特征,但管道参数获取较为困难,且不能刻画岩溶管道形态变化。该方法具有一定通用性,可为实际应用提供指导。

Development of a new method for efficiently calculating of evaporation from the phreatic aquifer in variably saturated flow modeling

In this paper, we proposed a new method that has been developed based on the surface soil moisture content(SSMC) to more efficiently calculate the groundwater evaporation in variably saturated flow modeling. In this method, the empirical formula to calculate evaporation was modified and the value of the formula varies from zero to one as a closed interval. In addition, the simulation code for calculating the groundwater evaporation based on the SSMC method was incorporated into the EOS9 module of Tough2, a variably saturated flow modeling code. Finally, two numerical tests and a case simulation were conducted to verify the feasibility and accuracy of the SSMC method. Simulation results indicate that the SSMC method is capable of appropriately simulating the characteristics of water flow in vadose zone and the amount of evaporation with the variable water table. And such results are in coincidence with the value calculated by the logistic function method, and fit well with the measured data globally rather than locally.

Numerical simulation of response of groundwater flow system in inland basin to density changes

The developmental characteristics of groundwater flow system are not only controlled by formation lithology and groundwater recharge conditions,but also influenced by the physical properties of fluids.Numerical simulation is an effective way to study groundwater flow system.In this paper,the ideal model is generalized according to the fundamental characteristics of groundwater system in inland basins of Western China.The simulation method of variable density flow on the development of groundwater system in inland basins is established by using EOS9 module in TOUGHREACT numerical simulation software.In accordance with the groundwater streamline,the groundwater flow system is divided into three levels,which are regional groundwater flow system,intermediate groundwater flow system and local groundwater flow system.Based on the calculation of the renewal rate of groundwater,the analysis shows that the increase of fluid density in the central part of the basin will restrain the development of regional groundwater flow system,resulting in a decrease of the circulation rate from 32.28% to 17.62% and a certain enhancement to the local groundwater flow system,which increased from 37.29% to 51.94%.

Review of the algebraic linear methods and parallel implementation in numerical simulation of groundwater flow

The desire to increase spatial and temporal resolution in modeling groundwater system has led to the requirement for intensive computational ability and large memory space. In the course of satisfying such requirement, parallel computing has played a core role over the past several decades. This paper reviews the parallel algebraic linear solution methods and the parallel implementation technologies for groundwater simulation. This work is carried out to provide guidance to enable modelers of groundwater systems to make sensible choices when developing solution methods based upon the current state of knowledge in parallel computing.

Application of HYDRUS-1D in understanding soil water movement at two typical sites in the North China Plain

Recharge and discharge, such as rainfall infiltration and evapotranspiration in vertical direction, are major processes of water cycle in the shallow groundwater area of the North China Plain. During these processes, soil water movement in the unsaturated zone plays an important role in the transformation from rainfall infiltration to groundwater. The soil water movement models were developed by using HYDRUS-1D software at two typical experimental sites in Cangzhou(CZ) and Hengshui(HS) with different soil, vegetation and similar climate conditions. As shown in the results, the comparison in precipitation infiltration features between the two sites is distinct. The soil water experiences strong evaporation after precipitation infiltration, which accounts for 63% of the total infiltration at the HS site where the soil is homogenous. It is this strong evaporation effect that leads to slight increase of soil water storage. At the CZ site, where the soil is heterogeneous, the evaporation effect exists from July to October of the simulation period. The total evaporation accounts for 33% of the total infiltration, and the evaporation rate is slow. At the end of the simulation period, the soil water storage increases and the water table decreases, indicating a strong storage capacity at this site.

Column test-based features analysis of clogging in artificial recharge of groundwater in Beijing

With the completion of South-North Water Transfer Project in China, plenty of high quality water will be transported to Beijing. To restore the groundwater level in Beijing, part of transferred water is planned to be used for artificial recharge. Clogging is an unavoidable challenge in the artificial recharge process. Therefore, a test is designed to analyse clogging duration and scope of influence and to test the reinjection properties of different recharge media. The test employs the self-designed sand column system with variable spacing and section monitoring, composed of four parts: Sand column, water-supply system, pressure-test system and flow-test system, to simulate the clogging of artificial recharge of sand and gravel pits. The hydraulic conductivity levels of all sand column sections are obtained to analyse the clogging of the injection of different concentrations in media of different particle sizes. In this experiment, two kinds of media are used–round gravel from sand and gravel pit in Xihuang village and the sand from sand and gravel pit by the Yongding River. The concentrations of recharge fluid are respectively 0.5 g/L and 1 g/L. The results show that clogging usually lasts for 20 hrs., and the hydraulic conductivity drops to the original 10%. Clogging usually occurs at 0–12 cm section of the sand column. The scope of influence is 0–60 cm. In column 3 and 4, whose average particle sizes are larger, section 20–50 cm also suffers from clogging, apart from section 0–12 cm. The effective recharge times are respectively 33 hrs. in column 1, 14 hrs. in column 2, 12 hrs. in column 3 and 12 hrs. in column 4. The larger the average particle size is, the quicker the clogging occurs. In media of larger particles, the change in suspension concentration does not have significant influence on the development of clogging. In conclusion, it is suggested that during artificial recharge, the conditions of reinjection medium should be fully considered and effective method of recharge be employed in order to improve effective recharge time.

Forecasting of water yield of deep-buried iron mine in Yanzhou, Shandong

This paper compares analytical and numerical methods by taking the forecasting of water yield of deep-buried iron mine in Yanzhou, Shandong as an example. Regarding the analytical method, the equation of infinite and bilateral water inflow boundary is used to forecast the water yield, and in the case of numerical simulation, we employed the GMS software to establish a model and further to forecast the water yield. On the one hand, through applying the analytical method, the maximum water yield of mine 1 500 m deep below the surface was calculated to be 13 645.17 m3/d; on the other hand, through adopting the numerical method, we obtained the predicted result of 3 816.16 m3/d. Meanwhile, by using the boundary generalization in the above-mentioned two methods, and through a comparative analysis of the actual hydro-geological conditions in this deep-buried mine, which also concerns the advantages and disadvantages of the two methods respectively, this paper draws the conclusion that the analytical method is only applicable in ideal conditions, but numerical method is eligible to be used in complex hydro-geological conditions. Therefore, it is more applicable to employ the numerical method to forecast water yield of deep-buried iron mine in Yanzhou, Shandong.

Research on hydrogen and oxygen isotopes of paleoclimate reconstruction in Nuomuhong

As a typical alluvial-proluvial fan area in the Qaidam Basin, Nuomuhong is important to the research on paleoclimate reconstruction in proluvial fan areas and basin climate change and ecological protection. This paper analyzes features of 2H, 3H, 18 O and 14 C isotopes in Nuomuhong and reconstructs paleoclimate in this area. According to the results: since 28 ka B.P., the ground average temperature decreases and then increases in the Qaidam watershed, reaching the lowest in 17.7 ka B.P. before increasing gradually. In the past 30 000 years, average temperature has changed ranged from 1 ℃ to 5 ℃ in this area; the lowest temperature was different from today’s temperature only by 3 ℃. This shows that climate conditions and natural environment in this area have been relatively stable in the past 30 000 years.

Research Progress of the Geological Environment in Ecological Planning

The geological environment is the basis of ecological planning. In this article, the factor analysis combined with Analytic Hierarchy Process(AHP) and GIS(geographic information technology) was used. The method sets geological disasters, landform type,surface slope, soil type and erosion as ecological suitability of geology factor; distribution of surface water,precipitation distribution,hydraulic engineering and degree of groundwater development as ecology suitability of water resources. Huairou, located in Beijing, was set as an example through the method. The article evaluated the suitability of the geological environment to ecology and solved quantitative description about the key technologies of the degree of influence to ecology which is affected by the geological environment. In the end, a theoretical guidance and a kind of technical method of establishing a scientific ecological planning system and guiding ecological planning were provided.

筋膜切开减压术治疗挤压综合征家兔模型的实验研究

目的:观察筋膜切开减压术在挤压综合征家兔模型的治疗中能否起到积极作用,并指导临床救治工作。方法:选取健康成年新西兰家兔(不分雌雄)70只。随机分为未行切开减压的实验对照组(10只)和切开减压组(即减压组60只),2组均在挤压4 h后解压,减压组根据解压后行筋膜切开减压时间将其分为6个亚组(每个亚组10只):即刻切开组(0 h)、2 h后切开组、4 h后切开组、6 h后切开组、8 h后切开组及10 h后切开组,分别标为A-F组,对照组设为G组;测量A-G组挤压4 h后及减压组(A-F组)减压术后第2 h、6 h、12 h的静脉血,检测血BUN、Cr、AST、ALT、CK、CK-MB、K^+、Ca^(2+)、MYO等生化指标;24小时后取挤压处的肌肉、肾脏、肝脏、心肌并立即做切片处理,并在光镜下进行检测分析。结果:两组挤压后4 h血BUN、Cr、AST、ALT、CK、CK-MB、K+、Ca2+、MYO差异无统计学意义(P>0.05);两组资料具有可比性。挤压伤组与对照组在各时间点生化指标差异均无统计学差异(P>0.05);各亚组之间在相同时刻生化指标也无统计学差异(P>0.05)。各亚组内随时间变动其BUN、Cr、AST、ALT、CK、CK-MB指标均呈上升趋向;而差异K^+、Ca^(2+)、MYO指标呈下降趋势;有统计学意义(P<0.05),有一定的时间依赖性。结论:早期行筋膜切开减压术在挤压综合征家兔模型的早期治疗中无明显的疗效;筋膜切开减压术并不可以改善患机体全身多脏器损伤情况。

高海拔地区家兔挤压综合征模型的初步实验研究

目的:建立一种适合高海拔地区的、简单有效并且可复制的家兔挤压综合征(crush syndrome,CS)实验模型,为在高原地区进一步研究CS打下基础。方法:健康成年新西兰家兔50只(饲养和实验地为西宁,海拔2260 m)。随机分为1组对照组及9个实验组,按照挤压重量(20 kg、30 kg、40 kg)和挤压时间(4 h、6 h、8 h)的不同进行排列组合后形成9种不同的挤压条件,实验组于解除挤压后6 h取静脉血检测血BUN、Cr、AST、ALT、CK、K+,解除压迫后24小时取家兔心肌、肾脏、肝脏、挤压处大腿四头肌行病理检查。对照组5只家兔作为空白对照,仅作麻醉处理不做挤压,在相同的时间点上取血及组织标本。结果:所有实验组家兔双后肢出现了明显的肿胀(P<0.05);所有实验组家兔在解压后6 h检测血BUN、Cr、AST、ALT、CK变化与对照组相比较均有统计学意义(p<0.05),而且随着压迫重量和压迫时间的增加,各数值也随之增加;受压肌肉及肝肾组织活检提示均有显著的病理改变;但是随着压迫重量和时间的增加,实验组家兔死亡率也随之升高。结论:随着挤压重量和挤压时间的增加可加重挤压综合征的严重程度,在高海拔地区,为了保证较低死亡率可采取挤压双后肢、挤压重量为20 Kg、挤压时间为4 h作为高海拔地区挤压综合征家兔模型的实验条件。