真空预压加固夹薄弱透水层软土固结特性分析

由于土的沉积历史原因,实际软土地基中常含有薄透水层,如何分析薄透水层对地基固结过程的影响是地基处理效果评价的关键。笔者利用室内模型试验装置开展了3组真空预压法加固夹薄弱透水层软土地基效果研究,以分析不同厚度的透水层对真空预压法加固软土地基固结的影响;利用已有成层砂井地基固结理论分析透水层透水特性和土层厚度对软土固结的影响。试验结果表明,透水层可加快超静孔隙水压力的消散,消散速率与透水层的厚度密切相关;透水层可以加快软土的固结速率。计算结果表明,当透水层厚度及渗透系数与软土厚度及渗透系数的比值介于0.1~100时,透水层对加快土体固结最为显著;当比值超过100时,透水层已接近完全排水边界。加固软土层厚度与砂井半径的比值与地基固结速率和透水层作用密切相关,随着比值的增大,砂井地基固结时间增长,透水层加快软土固结速率的作用越来越不明显,当比值大于8时,透水层对地基固结速率基本影响很小。透水层可以显著改善井径比、涂抹效应增大对地基固结速率减缓的影响。因此,真空预压工程中若需要设置水平向透水层,透水层竖向间距不宜大于其厚度的8倍。

夹薄透水层软土地基砂井固结机理

夹薄透水层软土地基砂井固结机理汤连生１）周萃英１）刘增贤２）杨建林１）（１）中山大学地球科学系，广州５１０２７５；２）山东省地质矿产局）关键词薄透水层，软土，砂井，固结机理分类号Ｐ６４２珠江三角洲地区软土土质松软、含水量高、孔隙比大、压缩性大，但含粉...

薄透水层大口井设计及涌水效果分析

根据已建2座大口井的工程实例，对建造薄透水层大口井中，非完整式大口井与完整式大口井出水量进行了分析，从地下水动力学理论，井壁进水方式设计原理出发，探讨、比较两种成井进水方式影响大口井涌水量的原因，结果表明，在透水层厚度5－10m条件下，井底井水的非完整式大口井的产水量远高于井壁进水的完整式大口井的产水量。

豫西陕渑煤田高水压薄隔水层工作面底板水害综合治理技术研究

针对目前煤田工程建设过程中遇到的高水压薄隔水层工作面底板水害问题,本文以实际工程项目为例,分析了煤田高水压薄隔水层工作面底板水害综合治理流程,并提出综合治理技术的应用要点。综合治理技术人员应充分结合工程项目的实际情况,在严格按照水害综合治理流程的情况下,达到既定的水害治理技术应用效果。

HF激光脉冲与水柱表面相互作用产生电信号(英文)

研究了脉冲HF激光与水柱表面相互作用下电信号的产生过程。电信号显示了与激光能量线性相关的峰值间有时间间隔的两峰结构,且第二个尖峰在水柱底部的蒸汽腔塌缩后出现。实验还显示电信号的幅值和激光脉冲照射过程中是否存在膨胀和挤压的薄水层密切相关。如果在电池上边缘和石英平板(石英板紧邻电池,并与水柱上表面相接)之间存在一薄水层,电信号强度会增加10倍。

基于未确知测度理论的薄基岩厚松散含水层下煤层安全开采区域划定

厚松散层底部含水层单位涌水量、厚松散层底部黏土层厚度、覆岩厚度、导水断裂带高度和采高5个因素为影响薄基岩厚松散含水层下采煤安全性的关键因素。将关键因素进行处理分析,找到关键因素影响开采安全性的4个联结点,即底部含水层单位涌水量、覆岩厚度与采高平方根之比、底部黏土层层厚与采高之比、导水断裂带高度与采高平方根之比4个评价因子。将评价因子划分为5个等级,进而量化开采安全性。引入信息熵和未确知测度理论,建立综合评价模型,以某矿105个钻孔数据为例,进行开采安全性评价,并根据评价结果对可安全开采区域进行划定和预测。将评价、划定和预测结果,同工程实践及已有研究结果进行对比,发现吻合度较高。结果表明,在所研究的煤层赋存条件下未确知测度模型是可行的、有效的。

施用化学氮肥有讲究

要施于湿润土壤，氮肥只有溶化在土壤水分中，方可被作物根系吸收利用，土壤过于过湿，都不利于提高氮肥利用率。通常情况下，土壤湿度应以手抓土不干不滑，有湿凉佳。水田施氮肥，应控制在薄水层时施入，投后3天内勿排水。

Determination of astaxanthin and astaxanthin esters in shrimp shell by HPLC

A method for determination of astaxanthin and astaxanthin eaters in shrimp shell by high performance liquid chromatography is established.Shrimp shell are addressed with 5%hydrochloric acid to remove calcium ions.After shell is dried,organics from shrimp shell are extracted with anhydrous ethanol.The alcohol extrative of the shrimp shell is mixed with the ammonium sulfate to extract astaxanthin by aqueous two-phase extraction.The crude astaxanthin is collected,which is distributed in the middle layer of the aqueous two-phase layer.After distilled water is added to the crude astaxanthin,the aqueous solution is centrifuged,and the previous step is repeated for several times.The precipitation in centrifuge tube is collected and dried.The crude astaxanthin dried is dissolved with acetone,and the sample solution is separated by TLC.Every pigment on the TLC plate is collected and dissolved with acetone.The pigments are determined by high performance liquid chromatograph.The results show that aqueous two-phase system,3 mL alcohol extractive of astaxanthin and 4.5 mL 20%ammonium sulfate,can be used to acquire crude astaxanthin.The wavelength of the maximum peak of astaxanthin in ethanol solution is 472 nm.A variety of pigments can be separated from the crude astaxanthin by thin-layer chromatography,including free astaxanthin,astaxanthin monoester,astaxanthin diester,echinenone and other substances.It can be seen from high performance liquid chromatography that the appearance time of free astaxanthin is from 4 min to 5.5 min,and the appearance time of astaxanthin monoester is from 10.5 min to 27.8 min.The method is simple about the sample pretreatment and feasible about the determination of astaxanthin and astaxanthin esters in shrimp shell.

Practice and adaptable conditions classification of aquifer-protective mining in longwall coalface for shallow seam with thin bedrock

A set of adaptable conditions classification of aquifer-protective mining in the Iongwall coalface for shallow coal seams with thin bedrock was put forward to deal with the conflict between water protection and high efficiency for the mining field in west China. This classification was suitable for shallow coal seams with different thickness and was beneficial to the local environmental protection. Using the 3-Universal Distinct Element Code （3DEC） numerical software, the height of the fractured zones for shallow coal seams with thin bedrock was calculated and analyzed, and its predicting formula was achieved. Meanwhile, according to the lithology and the weathering degree of the shallow coal seam the thickness of the protective layer was determined as 10 m and the overlying water body of loose water-bearing sand for shallow coal seams with thin bedrock was divided into three types, namely, weak, medium and strong. Based on these, the necessary bedrock thickness of the Iongwall coalface for shallow coal seams with thin bedrock was confined according to the different mining height and water yield nature of the overlying loose water-bearing sand. Combined with the present mining status, a set of new methods of adaptable conditions classification of aquifer-protective mining technology in the Iongwall coalface for shallow coal seams with thin bedrock was put forward.

Overburden failure and the prevention of water and sand inrush during coal mining under thin bedrock

Coal mining under thin bedrock or thick unconsolidated soil layers brings mining problems related to these special geological conditions. The meaning of the term ''thin bedrock'' is defined through the thick- ness statistics of the coal seam and the bedrock layer. The coal-bearing strata having thick, unconsoli- dated aquifers and thin bedrock located at the Taiping Coal Mine in Shandong province were taken as a geological prototype for subsequent study. The geological, hydro-geological and engineering character- istics of the thin bedrock were analyzed. An engineering geological model was than established. Overbur- den failure and the development of ''Three Zones'' were studied by physical model tests. The rupture pattern and rock failure were analyzed for mining conditions under thin bedrock. The height of the caving zone and the freely flowing water fractured zone of different mining thicknesses were separately calcu- lated. The results show that a mining thickness greater than 3.5 m causes the height of the freely flowing water fractured zone to be sufficient to touch the weathered zone and the bottom of the Quaternary sys- tem aquifer, to various degrees. This, then, would lead to water and sand inrush into the working face. Measures to prevent water and sand flow inrush disasters by eliminating the power source are put fore- word. A field dewatering scheme was designed and observational data were obtained. The dewatering project had an obvious effect and the water level at working face number 8309 dropped to a safe level. The average draw down of the groundwater was observed to be 7.86 m. This showed that the dewatering project played a role in decreasing the hydraulic pressure and ensuring safety mining.

Colorimetric Method for Determination of Amino Acids on Thin Layer and Filter Paper Chromatography Using a Modified Ninhydrin Reagent

A simple and rapid colorimetric method for the and Whatman filter paper chromatography is described. determination of some amino acids on thin layer chromatography （TLC） The studied compounds are cysteine, proline, methionine, tryptophan glutmine, glycine, thyrosine, threonine, leucine and lysine. The method is based on the formation of color from the reaction of stannous chloride （SnCI2） and ninhydrin reagents. The procedure has been successfully applied to the assay of the standard amino acid preparation after TLC separation, and the results of the studied compounds were clear and favorable, comparing to the official methods. However, the improved TLC is much more efficient for the detection of amino acid. The main advantage of this method is that the detection of amino acids can be preformed visually.

Study on microwave-induced thin-layer drying of municipal sludge for fuel reclamation

Since the adverse factors such as deficient penetration and long reaction time have restricted the complete microwave-used drying of municipal sludge, the microwave-induced drying is considered, which has advantages in such aspects. The investigation of the microwave-induced drying to uncover the mechanism bears great meaning for its development and utilization. The effects of temperature and microwave cracking in municipal sewage sludge drying characteristics are stud- ied through municipal sewage sludge drying experiment. Experiments shows that higher drying temperature would lead to a more acutely changing drying rate （DR）. The DR had increased from 0.005 g/（g.min） to 0.060 g/（g·min）, which was 12 times enlarged, while the temperature rose from 70℃ to 160 ℃. The higher the temperature was, the earlier the peak value of DR appeared. The experiments indicated that the temperature was the decisive factor affecting the DR. The microwave-induced sludge reached the highest DR at the moisture rate （MR） of 40%, with a 20% grade promotion compared with that of the original one. The molecular fracture caused by microwave radiation had obviously accelerated the drying process and the DR was rising in proportion to the microwave radiation dose. The diffusion coefficient had been calculated according to Fick＇s law. In com- parison to that of the original one, the diffusion coefficient of microwave-induced sludge was obviously enlarged more than two times. By fit examinations, Model Weibull was proven to be the most fit one for thermal thin-layer drying of municipal sludge. By means of Arrhenius equation, the obtained average activation energy of municipal sludge was 37.1 kJ/（mol·K）.

Auxiliary transportation mode in a fully-mechanized face in a nearly horizontal thin coal seam

On fully-mechanized faces in nearly horizontal thin coal seams （NHTCS）, the selection of the auxiliary transportation mode is difficult. Generally, auxiliary transportation mainly includes trackless or rail transportation. Combined with a familiar NHTCS fully-mechanized face, a multi-attribute decision- making model was set up for the decision. The index weight was objectively determined with the fuzzy number and entropy method. The priority order of auxiliary transportation modes was obtained from the Preference Ranking Organization Method for Enrichment Evaluation （PROMETHEE）. The results show that： the net flow of the mode can be expressed by the function of the surrounding rock deformation of the roadway, the dimension of equipment and the thickness of the coal seam; Based on the cost type index, there is a positive correlation between the net flow with the height and width of the trackless auxiliary transportation equipment, respectively. The trackless auxiliary transportation equipment selection principle should be ＂height first then width＂. Combined with the field application of the trackless auxil- iary transportation in Liangshuijing coal mine, the proper method to achieve the safe and high-efficient exploitation of a NHTCS fully-mechanized face is trackless tvred vehicle auxiliary transportation.

Theoretical limiting concentration for mineralization of trichloromethane and dichloromethane in aqueous solutions by AOPs

It is widely stated that most organic contaminants could be completely mineralized by Advanced Oxidation Processes(AOPs). This statement means that the concentration of the organic contaminant at equilibrium(limiting concentration,LC)is low enough to be neglected.However,for environmental safety,especially drinking water safety,this statement needs to be verified from chemical engineering thermodynamic analysis.In this paper,trichloromethane(CHCl3)and dichloromethane(CH2Cl2) are selected as the model systems,and the equilibrium concentration(theoretical limiting concentration,TLC)for the mineralization of chlorinated methanes in aqueous solutions at the different initial concentrations of chlorinated methanes,pH values and·OH concentrations by AOPs are investigated by thermodynamic analysis.The results in this paper show that the TLC for the mineralization of CHCl3 and CH2Cl2 with·OH increases with increasing initial concentrations of CHCl3 and CH2Cl2,decreases with increasing concentration of·OH,and the TLC for the mineralization of CHCl3 decreases with increasing pH values except that the pH value changes from 3.0 to 3.5.For the mineralization of CH2Cl2 with·OH,at the concentrations of·OH obtained from the literature,there is no obvious change of the TLC with pH values,while as the concentrations of·OH increase by 10 and 100 times,the TLC decreases with the increasing pH values from 2.0 to 3.0 and from 3.5 to 4.5,and increases with the increasing pH values from 3.0 to 3.5 and from 4.5 to 5.0.The investigations in this paper imply that high concentration of·OH,a bit higher pH values(4.0–5.0)in acid environment and low initial concentrations of the organic contaminants are beneficial for the complete mineralization of chlorinated methanes by AOPs.