利用压实模拟计算地层古厚度及差异压实量的尝试

本文通过实例阐述了利用压实模拟计算地层古厚度和差异压实量的原理和方法,并对其方法的优缺点进行了讨论。

沉积物压实量分式及其在研究海面高度中的应用

推导出计算沉积物压实量的理论公式：Δｈ＝ｈ（ｎ０－ｎ）／（１－ｎ０）．指出造成海岸堆积平原中Ｑ２３海相顶面高程常比岩岸地面上的古海面遗迹的高程低数米至数十米的主要因素：①沉积物压实；②冰期低海面流水蚀低古地面；③局部构造下沉．逐步分解出这３个因子就能较正确确定古海面高度。

一种精整机压实强度的关键参数控制分析

通过对精整机的工作对象土壤特性进行分析,建立了土壤压实过程中的参数模型,获取在土壤压实过程中对压实强度有关键影响的控制参数。对不同影响参数进行试验验证,结果表明:在精整机工作过程中,压实力和压实滚轮直径对土壤压实强度和压实变形量影响显著,压实滚轮宽度对土壤压实强度和压实变形量影响不显著。研究可为精整机使用过程中参数调整提供理论指导。

黄河三角洲沉积物的自然固结压实过程及其影响

对黄河三角洲及下伏沉积物的压实量和压实过程及其引起的地面沉降进行了分析研究。分析认为 ,在厚度为 15m的新淤积的黄河三角洲沉积重压下 ,前三角洲粘土和下伏海相粘土总固结量可达约 1.3 5m ,海湾或烂泥湾及前三角洲和海相粘土总压缩量为 1.48m。这些粘土层在亚三角洲建设时期就开始受压固结 ,但是在亚三角洲废弃后 ,仍要经过几十年自然固结才会基本完成。除去前 10年的固结量 ,前三角洲粘土与下伏海相粘土叠加形成的 14m厚粘土在随后的 2 7年内可能会压缩 5 0cm ;而海湾或烂泥湾及前三角洲和海相粘土叠加成的 2 0m厚粘土在 5 0年内可能会压缩 86cm ,两者的年平均压缩速率都超过 17mm/a。固结量和速率与上负沉积物重量成正比 ,而亚三角洲沉积厚度从沉积中心向外围逐渐减少 ,所以下伏粘土固结量和速率也向周围逐渐降低。但从亚三角洲沉积厚度分布情况看 ,在大范围内 ,下伏粘土固结引起的地面沉降在几十年内都将比较明显 ,从而可能加重三角洲地区风暴潮和海岸侵蚀灾害 。

塑性组分对压实作用和储层物性的控制作用——以白音查干凹陷缓坡带下白垩统腾格尔组碎屑岩储层为例

塑性组分与压实作用和储层物性之间的定量关系目前尚不清楚。文中选取白音查干凹陷缓坡带开展塑性组分含量和压实量、储层孔隙度定量关系研究,探讨塑性组分对压实作用和储层物性的控制作用。白音查干凹陷缓坡带发育锡林好来、达尔其和翁特三大物源区,母岩形成的片岩岩屑和云母碎屑组成塑性组分。锡林好来和翁特地区塑性组分含量较低,与压实量不存在明显相关关系,储层孔渗随深度增大,减小较慢;达尔其地区塑性组分含量较高,且与压实量存在明显正相关关系,储层孔渗随深度增大,减小较快。研究显示:塑性组分含量较低(体积分数低于10%)时,对压实量和储层物性影响较小;塑性组分含量较高(体积分数高于10%)时,对压实量和储层物性具有明显的控制作用。

冲击压实技术在湿陷性黄土处理中的应用

介绍了 YCT- 2 5 k J冲击压实机在处理路基底层湿陷性黄土中的应用情况 ,其中包括确定含水量。

Water content and modulus relationship of a compacted unsaturated soil

In order to assess the performance of the embankment soil under various climate conditions during the period of service, the modulus behaviour of an unsaturated compacted soil is evaluated using the constant water content triaxial test. Since the water content measurement method is simple and economical and it is used widely in engineering, the soil suction is replaced by the water content and the relationship between the water content and the modulus is developed. The compacted samples are prepared with different compacted water contents, and samples with a similar water content subjected to drying or wetting procedures prior to the triaxial test are also investigated. The effect of the water content and the confining pressure on the modulus is analyzed. The results show that the modulus decreases with the increase in the water content and a power function can be proposed to quantitatively describe the relationship between the modulus and the water content in the range of the measured water content. The modulus increases with the increase in the confining pressure of the compacted soil. However, the effect of the water content on the modulus is more pronounced than that of the confining pressure. This research can be referenced for the compacted embankment soil assessment in-service period.

Dynamic effects of high-pressure pulsed water jet in low-permeability coal seams

Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.

Wave-electric field coupling imaging diagnostic method for filled subgrade

Thick earth-rock filled embankment of large earthwork volume often occurs during the construction of expressways in mountainous and hilly areas. The compaction quality of earth-rock filled subgrade will directly affect the settlement deformation and stability of the embankment after filled. Therefore, effective evaluation on the compaction quality of the earth-rock filled subgrade is an unsolved critical technical issue to control the construction quality of highway engineering. Based on the wave propagation and electrical resistivity characteristics of the earth and rock fillings, a theoretical model of the compaction quality detection by wave-electric field coupling imaging diagnostic method was established. Then, two filled subgrade models containing cavities and heterogeneous bodies respectively were make separately, and by the wave velocity testing and electrical resistivity testing, the wave-electric field coupling imaging diagnostic method was applied to these two model. The result shows that it is feasible to use the wave testing technique and the electrical resistivity testing technique for a diagnostic test of the subgrade compaction quality. Based on the abnormal areas reflected by the wave velocity imaging and electrical resistivity imaging results, we are able to analyze the scope and site of distress but not able to quantitatively evaluate the subgrade compaction quality. We can accurately qualitatively analyze the subgrade compaction quality based on the wave-electric field coupling calculation model of fill subgrade quality proposed by this paper.

Micro-failure process and failure mechanism of brittle rock under uniaxial compression using continuous real-time wave velocity measurement

In this study,the micro-failure process and failure mechanism of a typical brittle rock under uniaxial compression are investigated via continuous real-time measurement of wave velocities.The experimental results indicate that the evolutions of wave velocities became progressively anisotropic under uniaxial loading due to the direction-dependent development of micro-damage.A wave velocity model considering the inner anisotropic crack evolution is proposed to accurately describe the variations of wave velocities during uniaxial compression testing.Based on which,the effective elastic parameters are inferred by a transverse isotropic constitutive model,and the evolutions of the crack density are inversed using a self-consistent damage model.It is found that the propagation of axial cracks dominates the failure process of brittle rock under uniaxial loading and oblique shear cracks develop with the appearance of macrocrack.

Intelligent compaction theory of high roller compacted concrete dam

The concept and realization process of intelligent compaction for the construction of high roller compacted concrete dam were presented, as well as the theory of monitoring and intelligent feedback control. Based on the real-time analysis of the compaction index, a multiple regression model of the dam compactness was established and a realime estimation method of compaction quality for the entire work area of roller compacted concrete dam was proposed finally. The adaptive adjustment of the roiling process parameters was achieved, with the speed, the exciting force, the roller pass and the compaction thickness meeting the standards during the whole construction process. As a result, the compaction quality and construction efficiency can be improved. The research provides a new way for the construction quality control of roller compacted concrete dam.

Vapor Pressure Measurement and Correlation of 2-Methyl-Butanol Acetate Containing Calcium Chloride

The CaCl2 solubility in 2-methyl-butanol acetate and the vapor pressure of 2-methyl-butanol acetate containing CaCl2 were measured in the range of 90-135°C and from very low salt concentration to saturation.The experimental data were correlated with two equations,a modified Antoine equation with the dissolved salt taken into account and a nonrandom two liquid-electrolyte（e-NRTL）model.Both models are in good agreement with the experimental data.This study provides essential physical data for further investigation of vapor-liquid equilibrium system containing salt.

Experimental Measurements and Correlations Isobaric Vapor-Liquid Equilibria for Water ＋ Acetic Acid ＋ Sec-butyl Acetate at 101.3 kPa

Isobaric vapor-liquid equilibrium(VLE) data for acetic acid + sec-butyl acetate and water+acetic acid + sec-butyl acetate systems were determined at 101.3 kPa using a modified Rose type.The nonideality of the vapor phase caused by the association of the acetic acid was corrected by the chemical theory and Hayden-O'Connell method.Thermodynamic consistency was tested for the binary VLE data.The experimental data were correlated successfully with the Non-Random Two Liquids(NRTL) model.The Root Mean Square Deviation(RMSD) of the ternary system was 0.0038.The saturation vapor pressure of sec-butyl acetate at 329 to 385 K was measured by means of two connected equilibrium cells.The vapor pressures of water and sec-butyl acetate were correlated with the Antoine equation.The binary interaction parameters and the ternary VLE data were obtained from this work.

Determining areas in an inclined coal seam floor prone to water-inrush by micro-seismic monitoring

The failure depth of the coal seam floor is one important consideration that must be kept in mind when mining is carried out above a confined aquifer.Determining the floor failure depth is the essential precondition for predicting the water-resisting ability of the floor.We have used a high-precision microseismic monitoring technique to overcome the limited amount of data available from field measurements. The failure depth of a coal seam floor,especially an inclined coal seam floor,may be more accurately estimated by monitoring the continuous,dynamic failure of the floor.The monitoring results indicate the failure depth of the coal seam floor near the workface conveyance roadway（the lower crossheading） is deeper and that the failure range is wider here compared to the coal seam floor near the return airway（the upper crossheading）.The results of micro-seismic monitoring show that the dangerous area for water-inrush from the coal seam floor may be identified.This provides an important field measurement that helps ensure safe and highly efficient mining of the inclined coal seam above the confined aquifer at the Taoyuan Coal Mine.

Experimental research on overlying strata movement and fracture evolution in pillarless stress-relief mining

In multiple seams mining, the seam with relatively low gas content （protective seam） is often extracted prior to mining its overlying and/or underlying seams of high gas content and low permeability to minimize the risk of high gas emission and outbursts of coal and gas. A key to success with this mining sequence is to gain a detailed understanding of the movement and fracture evolution of the overlying and underlying strata after the protective seam in extracted. In Zhuji mine, the No. 11-2 seam is extracted as a protective seam with the pillarless mining method by retaining goal-side roadways prior to its overlying No. 13-1 seam. An investigation has been undertaken in the panel 1111 （1） of Zhuji mine to physically simulate the movement and fracture evolution of the overlying strata alter the No. 1 I-2 seam is extracted. In the physical simulation, the displacement, strain, and deformation and failure process of the model for simulation were acquired with various means such as grating displacement meter, strain gauges, and digital photography. The simulation result shows that： （1） Initial caving interval of the immediate roof was 21.6 m, the first weighting interval was 23.5-37.3 m with the average interval of 33.5 m, and the periodic weighting interval of the main roof was in a range of 8.2-20.55 m and averaged at 15.2 m. （2） The maximum height of the caving zone after the extraction of No. 11-2 seam was 8.0 m, which was 4 times of the seam mining height and the internal strata of the caving zone collapsed irregularly. The mining-induced fractures developed 8-30 m above the mined No. 11-2 seam, which was 7.525 times of the seam mining height, the fracture zone was about 65° upward from the seam open-off cut toward the goaf, the height of longitudinal joint growth was 4-20 times of the mining seam height, and the height of lateral joint growth was 20-25 times of the mining seam height. （3） The ＂arch-in-arch＂ mechanical structure of the internal goaf was bounded by an expansion angle of broken strata in the lateral direction of the retained goaf-side roadway. The spatial and temporal evolution regularities of over- burden＇s displacement field and stress field, dynamic development process and distribution of fracture field were analyzed. Based on the simulation results, it is recommended that several goaf drainage methods, i.e. gas drainage with buried pipes in goaf, surface goaf gas drainage, and cross-measure boreholes, should be implemented to ensure the safe mining of the panel 1111 （1）.

Vapor Pressure Measurement of Water+1,3-Dimethylimidazolium Tetrafluoroborate System

In absorption cycles,ionic liquid(IL)1,3-dimethylimidazolium tetrafluoroborate([Dmim]BF4)may be a promising absorbent of working pair using water as refrigerant.The vapor pressures of[Dmim]BF4 aqueous solution were measured with the boiling-point method in the temperature range from 312.25 to 403.60 K and in the mass concentration range of 65%to 90%of[Dmim]BF4.The experimental data were correlated with an Antoine-type equation and the Non-Random Two-Liquid(NRTL)model,and the average absolute deviations between the experimental and calculated values were 1.06%and 1.15%,respectively.For the[Dmim]BF4 aqueous solution,the experimental vapor pressures show negative deviations from the calculated data with Raoult's law.For higher mass concentration of the IL,the deviation is more negative.In addition,the vapor pressures,the hydrophilicity and the solubility of[Dmim]BF4 aqueous solutions were compared with those of[Dmim]Cl aqueous solutions and [Bmim]BF4 aqueous solutions at IL-mole fraction of 0.20.

Hydraulic and mechanical properties of wax-coated sands

Wax-coated sands are a new category of synthetic soils, which are gradually becoming a reliable construction material. Because of their valuable drainage ability and mechanical properties, wax coated sandy soils are specifically applicable to pavement construction of horseracing tracks and sport fields. Although the mechanical and hydraulic properties of these synthetic soils are well-proven, there is still a lack of studies on how the soil samples behave differently when mixing with different wax fractions. Adding the wax affects permeability and compressibility of pure sand. Intensity of influences is a function of weight percentage of wax that has been added, and other physical and environmental factors. The effects of wax content on hydraulic properties(permeability), and mechanical properties(stress strain behavior, compressibility) of sandy soils based on a series of experimental efforts were investigated. Obtained experimental results infer that increasing the amount of wax up to 6% causes an about 50% increase in permeability, mainly because of the significant effect of wax in lowering the friction along with covering and filling the angular parts of particles' surfaces and forming rounded particles. In addition, wax-coated sands show a 20% to 60% decrease in confined compression modulus compared to non wax-coated sands.

Control of Mechanical Properties According to Content Ratio of Copper Coated Carbon Nanotubes in Alumimum Composites

The main objective of this study is to enhance the strength of CNTs （carbon nanotubes） which reinforced AI matrix composites by introducing an appropriate amount of Copper（Cu） into the composite material. AI-Cu/MWCNTs （multi-walled carbon nanotubes） nanocomposites were produced via compaction, sintering and hot extrusion process of AI-Cu/MWCNTs powders, which were fabricated by a conventional ball mill process with AI powders and Cu-MWCNTs composite powders which were synthesized by molecular level mixing technique. Also the change of mechanical properties with different content ratio of Cu/MWCNT composite powders in A1 matrix is analyzed. It is found that the addition of the proper Cu/MWCNTs powders which are well distributed in AI matrix leads to high mechanical stiffness. The 2 wt% Cu/MWCNTs reinforced A1 composites which exhibited 3.2 times higher tensile strength and 4.4 times higher yield strength than pure AI.

MaI-Uniformity of Two-Phase Flow Distribution in Merged Pipe Distributor under Different Outlet Channel Length

Two-phase flow distributions in the merged pipe distributor have still remained mal-uniformity problem and the causes have not clearly discovered yet. Therefore, the enhancement study is needed, absolutely. The experimental was carried out upon the distributor constructed by acrylics resembling merged triple pipe, 8 mm in diameter of inlet channel and two set 5 mm in diameter of each outlet channel, set horizontally sideways. Three flow patterns were fed, i.e., bubble, slug and stratified flow, observed via high speed video camera. The pressure distribution was measured by series of U-tube water gauge manometer. The flow patterns, phase distribution and pressure drop were analyzed by CFD software, validated by experimental data and compared by existing correlation, analytically. The experiment is extended by modeling, in order to vary three inclinations of distributor： horizontally, 45° and vertically up-ward as well as to vary three outlet channel lengths with length ratio lc/dc： 3.2, 10 and 70. It was revealed that the two-phase flow distribution tends to be mal-uniform and to transform to different flow pattern in outlet channels. These are promoted by different： outlet channel length, feeding two-phase flow pattern in inlet distributor and inclination angle. The changing of flow pattern is driven by fluctuating velocity in both upper and lower outlet channel.

Study of Sandy Soil Compaction

In this paper, a study of sandy soil compaction with different granulometry and moisture content has been performed, and soil mechanical property variations in moisture and granulometry have been investigated. Investigations were performed to compare hydrostatic compression test （HCT） responses and evaluate the compression index, Cc, which is an indicator of the soil＇s susceptibility to compaction-induced damage. The experiments have been performed on 24 soil samples typologies. Each sample has been obtained by combining three types of soil granulometry （types A, B and C） with a relative content varying from 0% to 100% in 20% increments. Soil type A had a granulometry ranging between 0.5 mm and 1 mm, type B between 0.25 mm and 0.5 mm, and type C less than 0.25 mm. These samples were representative of a sandy soil, chemically inactive and had various granulometries and initial moisture contents. A cell for HCT has been set up to allow the initial volume measurement of the test pieces and the subsequent changes during HCT with an estimated error less than 0.1 cm3. All samples were pre-compacted and prepared in agreement with the actual standards. The experimental data are reported in diagrams, the data allowed comparison of the mechanical behaviors between the considered unsaturated soils and underlined how soil moisture and granulometry affect soil response during HCT. Furthermore, because of the methodology used, the equipment was very economical.