软土含砾地层斜孔成孔方法探讨

在锚固工程成孔中，软土含砾地层成孔困难，钻进效率低，效率效益差，针对这种情况分析了地层特点和采用不同成孔方法施工存在的问题，找出了一种比较适应的钻进成孔方法，并通过生产实践证明效果较佳，为软土含砾地层倾斜孔成孔提供了一种新方法。     

旋挖钻机与双聚合泥浆在桩基施工中的应用

介绍了旋挖钻机和双聚合泥浆在工程中的应用，通过工程实例介绍了旋挖钻机的施工方法，着重介绍了双聚合泥浆的制备、特点和技术要求。     

Characterizing the rheology of laterite slurries

The viscous behaviour of laterite slurries was characterized by measurements of shear stress at constant and changing shear rates. Steady state stresses were obtained after accounting for the settling solids: the values show that the fluids possess viscosities of order 100 mPa s and are moderately shear-thinning, for solid volume fractions from 0.06 to 0.18 and for shear rates between 10 and 1000 s⁻¹. Transient stress measurements were made for steps down in shear rate and for ramps down and up in shear rate. It was found that the Bingham–Maxwell model provides good fits to the transient data, both at low concentrations, where yield behaviour is dominant, and at high concentrations, where elasticity is dominant. For volume fractions of 0.10 or greater, relaxation times were found from step tests to be of order 10 s, but relaxation times found from the ramp tests were generally several times higher.     

悬浮液进样—石墨炉原子吸收光谱法测定琥珀中微量铅

报道了以NH4H2PO4为基体改进剂，采用悬浮体制样石墨炉原子吸收光谱法直接测定琥珀中微量铅的方法。试验了影响测定的主要因素。在优化实验条件下。方法的检出限为0．038μg／g，Pb的质量浓度为0～80μg／L时，工作曲线线性关系良好。对于ω(Pb)=5．71μg／g样品的测定，相对标准偏差(RSD，n=5)为6．83％。     

利用铝−有机质絮状物降低渗透系数的试验研究

防渗对堤坝等水利工程、地下工程和污染物迁移都具有重要意义。基于自然灰化土层形成过程中因金属离子和有机质络合反应形成不透水土层的过程,提出了利用六水合氯化铝（AlCl3·6H2O）和有机质（OM）相互反应生成Al-OM絮状物来降低渗透系数的方法。开展了系列的注入试验,探究了浆液浓度、注浆速度和砂土颗粒级配对渗透系数降低和形成屏障长度的影响。研究结果表明：该方法可以有效地降低砂土的渗透性;渗透系数降低的速度随着浆液中Al-OM絮状物浓度的增大而增加;由于絮状物浓度的增加,孔隙堵塞的速度增快,从而阻止了其继续扩散,形成的屏障长度随之减小;Al-OM絮状物的尺寸随注浆速度的增大而减小。当注浆速度较大时,Al-OM絮状物的尺寸较小,因此渗透系数降低慢而扩散距离远。砂土的颗粒级配对渗透系数降低有重要影响,粗颗粒含量越大,渗透系数降低越小。     

外加剂对低温水泥浆性能的影响试验研究

为解决在普通硅酸盐水泥（P.O42.5）或混凝土施工中遭遇低温环境而不能顺利凝固的问题。对普遍使用的硅酸盐水泥进行了基础性能测试试验,使用早强剂与高效减水剂对水泥进行调整性能,寻找出最佳的调整方案,对比调整前后水泥浆及水泥石强度等各项数据。结果表明10%早强剂、2‰JSS高效减水剂的调整方案较好地改善了水泥浆的流动性、凝结时间、水化热放热速率、结石率及水泥石的早期强度等问题。研究成果对低温条件下的混凝土施工有一定的参考价值。     

Effect of the pressurized duration on improving dredged slurry with air booster vacuum preloading

Abstract

Compared with traditional vacuum preloading, air booster vacuum preloading is more effective at strengthening dredged slurry and improving the consolidation process. Although many engineering practices have shown that the pressurized duration has a significant effect on the reinforcement effect, there is no standard available for determining the pressurized duration. In this study, five dredged slurry samples were tested to examine the effect of different pressurized durations on the consolidation. An extensive monitoring system was used to measure the vacuum pressure, pore water pressure, settlement, and water discharge during the test, while the water content and shear strength were measured after the test. The collected monitoring data were comprehensively analyzed to evaluate the reinforcement effect. The results revealed that the pressurization system can be used to reinforce deep dredged slurry and make the whole soil layer more homogeneous. If the pressurized duration is too short, the dissipation of pore water pressure is too little to achieve the pressurization effect. If the pressurized duration is too long, too much gas will be in the soil and enter the vacuum system, which will significantly reduce the vacuum pressure and thus the reinforcement effect. Based on these findings, the optimal pressurized duration was obtained.     

岩溶地区冲孔灌注桩的施工方法

以龙岩地区岩溶地带某一项目施工为例，分析冲孔灌注桩孔内漏浆、塌孔的原因，探讨在岩溶地区预防和处理塌孔的方法：改善泥浆品质，安放钢护筒，挤压黄土入裂隙，减小泥浆渗透，以及分层加入一定量水泥，使其形成水泥土护壁层。实践证明，诸类方法的使用可有效遏制孔内漏浆和塌孔，提高施工效率。     

Additives for Slurry Shields in Highly Permeable Ground

Summary. For tunneling projects in saturated soils tunnel boring machines (TBMs) with slurry shields are widely used. However, in coarse, highly permeable soils the suspension penetrates the ground and the required support pressure cannot be built up. For the Zimmerberg Base Tunnel near Zurich permeabilities much greater than 10⁻³ m/s were expected. This value is usually considered as the critical limit for the applicability of slurry shields. Therefore it was aimed to find additives for the bentonite suspension which would allow it to attain a higher suspension pressure. For these investigations an apparatus has been developed. It allows the maximum attainable support pressure for a given suspension and a ground to be determined. It reflects the real situation, produces reproducible results and is insensitive to the inevitable variation of individual parameters. In the tests the additives polymer, sand and vermiculite were studied and their effects on the attainable maximum suspension pressure investigated. For the best combination, i.e. with a well defined proportion of the individual components, suspension pressures could be attained which were about 10 to 20 times higher than those with an ordinary bentonite suspension. Successful excavation of the Zimmerberg Base Tunnel proved the validity of the laboratory tests containing 200 kg bentonite per m³ water.     

地方病高发区成井用胶质水泥浆的试验研究

通过地方病高发区成井用胶质水泥浆的试验研究，以普通水泥和膨润土为基本材料，同时添加改善材料性能的外加剂，研制了一种用于高砷、高氟、高矿化度地区水井成井的止水材料，具有流动性好、抗渗性高、不收缩、完全无毒、价格低廉等特点，特别是其高抗渗性和不收缩性非常适合地方病区成井时隔离劣质含水层，保证优质含水层与劣质含水层互不串通、不渗漏、不污染。