富水深埋隧道围岩渗透扰动高度计算方法研究

针对深埋富水隧道排水过程对周边围岩渗流场扰动问题,首先,采用数值模拟方法,探明隧道排水条件下围岩渗流场分布规律,提出围岩渗流扰动高度概念;同时,采用控制变量法,明确不同因素(水头高度、围岩渗透系数、隧道排水率)条件下围岩渗流扰动高度变化规律;其次,采用数理拟合方法,给出围岩渗流扰动高度分段计算方法;最后,采用室内相似试验,对所提出计算方法的合理性进行验证。研究表明:1)隧道排水后会对围岩渗流场产生扰动,但渗流场扰动范围仅在隧道拱顶以上一定高度内存在,即围岩渗流扰动高度。2)围岩渗透系数、水头高度、隧道排水率均分别与围岩渗流扰动高度呈正相关关系,且3个因素的影响程度依次降低。3)当给定渗透系数与排水率时,围岩渗流扰动高度随水头高度变化规律呈明显2段式特征。当水头高度不大于临界水头高度时,围岩渗流扰动高度随水头高度的增大呈线性增大趋势;当水头高度大于临界水头高度时,围岩渗流扰动高度为定值,为临界围岩渗流扰动高度。4)给出围岩渗流扰动高度的数学计算表达式,并将采用所提计算方法的计算结果与室内试验结果进行对比,验证所提方法的正确性及合理性。

含淹没植物明渠近床面区紊流特征高度试验研究

为研究含淹没植物明渠紊流统计参数垂向分布突变位置、理论床面和渗透高度的关系,进行了含淹没刚性植物明渠水流试验,使用圆柱铝棒模拟刚性植物,采用激光多普勒流速仪(LDV)测量流场,对由纵向流速、雷诺应力、局部阻力系数分布确定的特征高度和渗透高度进行研究,比较各类紊流特征高度的相对位置,分析植物密度与淹没度对其的影响。试验结果表明,在植物密度较大的情况下,近床面区流速沿垂向保持常数,雷诺应力梯度较小,一定高度处分布规律发生明显变化,能够较容易地确定流速梯度和雷诺应力梯度突变位置,淹没度对由3种方法确定的特征高度影响不明显;各种方法确定的特征高度中,雷诺应力特征高度与渗透高度更加接近;渗透高度随植物密度与淹没度的增大而增大;渗透高度与理论床面高度存在一定的线性关系。

工艺因素对RFI复合材料渗透成型影响的试验研究

采用模拟试验的方法研究了复合材料树脂膜渗透成型(Resin Film Infusion RFI)过程中树脂粘度及压力对渗透高度及浸渍质量的影响。实验结果表明,总体上树脂的粘度提高,复合材料的渗透浸渍高度下降。成型压力则对不同粘度体系及增强材料预处理情况有不同的结果,一方面提高树脂渗透驱动力,另一方面压实纤维床从而降低渗透率。但压力的提高总是有利于提高渗透浸渍质量,减少孔隙率。分析认为压力影响渗透高度的实质是渗透压力变化及纤维床的压实两种因素的共同作用结果。

Bending properties and fracture mechanism of C/C composites with high density preform

C/C composites with banded structure pyrocarbon were fabricated by fast chemical vapor infiltration（CVI）,with C3H6 as carbon source,N2 as carrier gas,and three-dimensional（3D） 12K PAN-based carbon fabric with high density of 0.94 g/cm3 as preform.Experimental results indicated that the fracture characteristics of C/C composites were closely related to the frequency of high-temperature treatment（HTT） at the break of CVI process.According to the load？displacement curves,C/C composites showed a pseudoplastic fracture after twice of HTT.After three times of HTT,load？displacement curves tended to be stable with a decreasing bending strength at 177.5 MPa.Delamination failure and intrastratal fiber fracture were observed at the cross-section of C/C composites by scanning electronic microscope.Because the content of pyrocarbon and fibers has a different distribution in layers,the C/C composites show different fracture characteristics at various regions,which leads to good toughness and bending strength.

高性能泡沫混凝土防水性能试验研究

为研究出一种新型高性能防水型泡沫混凝土,对其防水性能进行研究。通过在普通高性能泡沫混凝土中加入一定量的硬脂酸锌乳液防水剂配制成一种新型高性能泡沫混凝土测试其不同防水剂掺量和水灰比对泡沫混凝土的抗压强度、吸水率及抗渗高度的影响,并将试验结果进行对比分析,得到当水灰比为0.35,防水剂的掺量为2%时,吸水率为所有试验对照组最低,此时泡沫混凝土的防水效果最好,吸水率为最低。

塑钢纤维对高性能喷射混凝土的性能优化研究

为提高隧道支护系统的稳定性,研究在普通喷射混凝土内掺杂塑钢纤维材料,以提高其抗压、抗渗和力学支撑性能。塑钢纤维提升喷射混凝土性能的研究依托复合材料、纤维间距理论,试验结果显示:塑钢纤维混凝土的最大承受荷载为17.2 kN;最大平均渗透高度5.4 cm,为普通喷射混凝土的40.6%;最大渗透系数0.506×10^(-9) cm/s,为普通喷射混凝土的16.5%;塑钢纤维喷射混凝土的抗压性、抗渗性和韧性均优于普通喷射混凝土。

基于多组分矿物材制备混凝土用增效剂及其性能研究

利用优化颗粒级配和激发原理,基于多组分矿物材研发了一种可取代部分水泥的增效剂,研究其对混凝土工作性能、力学性能及耐久性能的影响,利用扫描电镜对混凝土的微观结构进行分析。结果表明:相较于基准组,增效剂的掺入可提高混凝土工作性能并降低其经时损失;当矿物材增效剂掺量不超过15%时,混凝土各龄期力学性能均较基准组有所提高;矿物材增效剂掺量为10%时效果最佳,28 d抗压和抗折强度较基准组分别提高了5.8%和18.0%,渗透高度降低了31.1 mm,电通量降低了19.5%,抗硫酸盐侵蚀性能大幅提升。

内掺型防水剂对混凝土性能的影响及其机理分析

研究了掺胶凝材料质量1%~5%复合型防水剂对混凝土工作性能、力学性能、抗渗性能、收缩性能和水化热特性的影响。结果表明,在最优掺量下,混凝土坍落度、流动度相较于基准组有所增大;28 d抗压强度提高了8.2%,抗折强度提高了7.4%;渗透高度仅为基准组的15.6%;干缩值早期有所减小,但后期增长较快;水化热温峰降低了3.8℃,温峰延迟了3.6 h。机理分析表明,防水剂主要是通过后期的激发作用,促进了更多的水化硅酸钙凝胶和Ca(OH)2的生成,填充材料的孔隙,增大了基材的密实度,进而显著降低孔隙率、细化了孔结构,在改善混凝土抗渗性能的同时,综合性能也明显改善。

Log identification method in complex sand reservoirs

In order to obtain effective parameters for complex sand reservoirs,a log evaluation method for relevant reservoir parameters is established based on an analysis in the gas-bearing sandstone with high porosity and low permeability,low porosity and permeability and on various characteristics of log responses to reservoir lithologies and physical properties in the Neopleozoic sand reservoir of the Ordos basin.This log evaluation method covers the Cook method that is used to evaluate the porosity and oiliness in high porosity and low permeability reservoirs and another method in which the mineral content,derived from geochemical logs,is used to identify formation lithologies.Some areas have high calcium and low silt content,not uniformly distributed,the results of which show up in the complex formation lithologies and conventional log responses with great deviation.The reliability of the method is verified by comparison with conventional log data and core analyses.The calculation results coincide with the core analytical data and gas tests,which indicate that this log evaluation method is available,provides novel ideas for study of similar complex reservoir lithologies and has some reference value.

Preparation of high-permeability NiCuZn ferrite

Appropriate addition of CuO/V2O5 and the reduction of the granularity of the raw materials particle decrease the sintering temperature of NiZn ferrite from 1200 °C to 930 °C. Furthermore, the magnetic properties of the NiZn ferrite prepared at low temperature of 930 °C is superior to that of the NiZn ferrite prepared by sintering at high temperature of 1200 °C because the microstructure of the NiZn ferrite sintered at 930 °C is more uniform and compact than that of the NiZn ferrite sintered at 1200 °C. The high permeability of 1700 and relative loss coefficient tanδ/μi of 9.0×10?6 at 100 kHz was achieved in the (Ni0.17Zn0.63Cu0.20)Fe1.915O4 ferrite.

An easily recoverable thermo-sensitive polyelectrolyte as draw agent for forward osmosis process

As a potential solution to the crises of energy and resources, forward osmosis(FO) has been limited by the development of draw agents. An ideal draw agent should be able to generate high osmotic pressure and can be easily recovered. In this study, a thermo-sensitive polyelectrolyte of poly(N-isopropylacrylamide-co-acrylic acid)(PNA)is developed as an efficient draw agent, and two easy and simple methods are proposed to effectively recover the polyelectrolytes. After adjusting the pH value of polyelectrolyte solutions to around 6.0, the polyelectrolyte can generate relatively high osmotic pressure, and induce average water fluxes of 2.09 and 2.95 L·m^(-2)·h^(-1) during12 h FO processes when the polyelectrolyte concentrations are 0.20 and 0.38 g·ml^(-1) respectively. After acidifying and heating to 70 °C, the PNA-10 polyelectrolyte can aggregate together because of hydrophobic association and separate from water, so it can be easily recovered by either simple centrifugation or gravitational sedimentation. The recovery ratios of PNA-10 polyelectrolyte in both methods are as high as 89%, and the recovered polyelectrolytes can be reused with almost the same FO performance as fresh ones. The results in this study provide valuable guidance for designing efficient and easily recoverable draw agents for FO processes.

一种新型的液体混凝土防水剂的制备

本文以聚乙二醇、甲基丙烯磺酸钠、对苯二酚等为原材料,过硫酸铵为引发剂催化聚合反应,反应完全后,再以有机硅酸盐作为载体、无机铝盐作为微膨胀组分,制备出一种具有微减水率及微膨胀性能的有机无机复合液体混凝土防水剂。该防水剂可通过简单涂抹在混凝土表面起防水作用,也可按4.0%掺量与混凝土减水剂一起拌制混凝土,试验表明,掺该防水剂的混凝土密实度高、抗渗防水性能好且28d混凝土抗压强度明显增大。