重庆松藻矿区复杂地层钻探技术探讨     

彭北怀  曾华光  李祖 《中国煤炭地质》2008,(7):59-61

重庆松藻矿区强风化地层厚度在700m左右,结构松软、涌水、漏失及水敏性地层反复出现。该区钻孔易出现坍塌、掉块、吸水膨胀缩径、孔斜等现象,施工难度较大,另外煤心采取率极低。在该矿区小鱼沱井田钻进时,采用快干水泥浆封堵及跟管钻进相结合的钻进工艺,并严格控制双聚低固相泥浆配方;在跟管钻进过程中,掌握控制其压力、转速,防止因压力过大或钻进太快而出现套管断脱。该孔历时4个月,终孔深度1261．72m,终孔斜度为8°,钻孔质量为特级。CK-28井成孔经验表明,在该区复杂地层钻进,采用边钻进边封堵及跟管钻进等技术,可有效解决易塌、涌水、漏失、孔斜等难题。  相似文献   

Shear strength characteristics of Irbid clayey soil mixed with iron filling and iron filling–cement mixture     

Mousa F. Attom 《Environmental Geology》2008,55(4):781-788

Iron filling and iron filling–cement mixture were used to improve the shear strength characteristics of Irbid clayey soil. For this purpose, five types of Irbid clay soils were obtained and mixed with iron filling and iron filling–cement mixture at different percentages. Two sets of prepared samples were mixed with the admixture. The first set was prepared by mixing the soil samples with iron filling alone at 2.5, 5.0, 7.5, and 10% by dry weight of the soil. The second set was prepared by mixing with iron filling–cement mixture at equal ratio of the same percentages of the first set. An unconfined compression test was performed in this study to measure the shear strength properties of the soils. The test results showed that the increase in the percentages of the iron filling and iron filling–cement mixture up to 10% will result in increasing the maximum dry density of the soil and increase the unconfined compressive strength and the secant of modulus of elasticity of the clayey soil. Also, the addition of iron filling–cement mixture increased the unconfined compressive strength and secant modulus of elasticity of the clayey soil higher than the addition of iron filling alone.  相似文献   

随机镇定与反镇定概述     

黄礼荣  邓飞其  宋明辉 《南京气象学院学报》2017,9(3):262-273

本文概述了随机镇定与反镇定理论的研究现状.主要回顾了一个微分方程的随机镇定与反镇定普遍理论及其发展,并围绕该理论的应用和扩展从四个方面阐述连续时间系统噪声镇定理论的当前发展概况.此外,本文还概述了离散时间系统随机镇定方面的最新进展.  相似文献   

随机非完整系统控制问题综述和展望     

冯文莉  张东凯  王朝立  杜庆辉 《南京气象学院学报》2017,9(3):314-318

随着随机非线性控制的发展,随机非完整系统的控制引起了学者们的注意.本文首先探讨了随机非完整控制系统的镇定问题,涉及严反馈链式系统的反馈镇定和不满足严反馈的移动机器人镇定等;其次,介绍了该系统跟踪控制及现状;最后,在总结现有结果的基础上,分析了随机非完整系统发展的趋势,给出了6个可能的研究方向.  相似文献   

硫铝酸盐“S”型瞬凝水泥的研究与机理探讨     

彭振斌 《地质与勘探》1996,32(6):53-57

简介了低温烧结的硫铝酸盐“Ｓ”型瞬凝水泥的基本情况;详细阐述了该水泥的水化机理、早强机理、速凝机理等。  相似文献   

Mechanism of Hg(II) immobilization in sediments by sulfate-cement amendment     

《Applied Geochemistry》2016

Reactive amendments such as Portland and super-sulfate cements offer a promising technology for immobilizing metalloid contaminants such as mercury (Hg) in soils and sediments through sequestration in less bioavailable solid forms. Tidal marsh sediments were reacted with dissolved Hg(II) in synthetic seawater and fresh water solutions, treated with Portland cement and FeSO₄ amendment, and aged for up to 90 days. Reacted solids were analyzed with bulk sequential extraction methods and characterized by powder X-ray diffraction (XRD), electron microscopy, and synchrotron X-ray absorption spectroscopy at the Hg L_III- and S K-edge. In amended sediments, XRD, SEM and sulfur K-edge XANES indicated formation of gypsum in seawater experiments or ettringite-type (Ca₆Al₂(SO₄)₃(OH)₁₂^.26H₂O) phases in fresh water experiments, depending on the final solution pH (seawater ∼8.5; freshwater ∼10.5). Analysis of Hg EXAFS spectra showed Cl and Hg ligands in the first- and second-coordination shells at distances characteristic of a polynuclear chloromercury(II) salt, perhaps as a nanoparticulate phase, in both seawater and fresh water experiments. In addition to the chloromercury species, a smaller fraction (∼20–25%) of Hg was bonded to O atoms in fresh water sample spectra, suggesting the presence of a minor sorbed Hg fraction. In the absence of amendment treatment, Hg sorption and resistance to extraction can be accounted for by relatively strong binding by reduced S species present in the marsh sediment detected by S XANES. Thermodynamic calculations predict stable aqueous Hg–Cl species at seawater final pH, but higher final pH in fresh water favors aqueous Hg-hydroxide species. The difference in Hg coordination between aqueous and solid phases suggests that the initial Hg–Cl coordination was stabilized in the cement hydration products and did not re-equilibrate with the bulk solution with aging. Collectively, results suggest physical encapsulation of Hg as a polynuclear chloromercury(II) salt as the primary immobilization mechanism.  相似文献   

Stabilization Mechanism and Effect Evaluation of Stabilized Silt with Lignin Based on Laboratory Data     

Guojun Cai  Songyu Liu  Junhai Li  Daobo Jie 《Marine Georesources & Geotechnology》2016,34(4):331-340

The potential of a lignin-based by-product to stabilize silt was evaluated. The physical and mechanical properties of silt in its natural state, as well as when treated with varying proportions of lignin, were analyzed. The parameters tested include the particle size distribution, Atterberg limits, compaction characteristics, unconfined compressed strength, pH value, and electrical resistivity. To understand the stabilization mechanism of lignin-treated silt at a microscopic level, scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and Fourier transform infrared resonance (FTIR) spectroscopy were also carried out on lignin and representative samples after 28 days of curing. The results indicate that the engineering properties of silt are improved by the addition of lignin. Particle size distribution is changed and plastic index is reduced from 8.8 to 7.7. After improvement, the maximum dry density increases and the optimum moisture content decreases, while the change of dry density with moisture content is enhanced. The treated silt has greater strength performance than the natural silt in terms of unconfined compressed strength and all of the samples have a pH value lower than 10. Curing time and moisture content have a significant impact on unconfined compressed strength but almost no effect on pH. Micro-chemical analysis reveals that the improvement of performance exhibited by lignin-treated silt may be mainly attributed to the cation exchange and the formation of more stable soil structure by lignin cementing. The stabilization mechanism of lignin-treated silt was proposed according to the results of chemical analysis. It is shown that lignin-based stabilizers have potential to improve the engineering properties of silt.  相似文献   

寒区再生集料水泥稳定碎石路基的力学和温缩性能北大核心CSCD     

张立群  张学峰  崔宏环 《冰川冻土》2022,44(2):506-514

为解决废旧沥青混合料(RAP)和铁尾矿砂(ITS)固废处理问题,将两者充当砂石料掺加到水泥稳定碎石中,通过无侧限抗压试验、弯拉试验和温缩试验对水泥稳定碎石进行路用性能研究,分析了RAP和ITS掺量对水泥稳定碎石的影响。结果表明:RAP掺量一定时(25%),ITS掺量增加有利于提高水泥稳定碎石的抗压强度和弯拉强度,但会增大材料的温缩应变和温缩系数,降低温缩性能,其中ITS45(ITS掺量为45%)有较好的温缩性能;ITS掺量一定时(60%),RAP掺量增加不利于水泥稳定碎石的抗压强度,但可以提高水泥稳定碎石的弯拉强度,降低温缩应变和温缩系数,其中RAP70(RAP掺量为70%)温缩性能达到最优;与ITS45相比,RAP70有更宽泛的施工温度区间。  相似文献   

MICP技术联合多孔硅吸附材料对锌铅复合污染土固化/稳定化修复的试验研究     

李驰  田蕾  董彩环  张永锋  王燕星 《岩土力学》2022,(2):307-316

近年来,工业和科技的快速发展使得重金属污染土固化/稳定化的修复研究成为热点。运用微生物诱导碳酸钙沉淀(MICP)技术联合吸附材料对锌铅复合重金属污染土进行固化/稳定化的修复,通过无侧限抗压强度试验、毒性浸出试验,评价处理前后污染土的固化效果与重金属的稳定化效果,结合扫描电镜(SEM)和X射线衍射(XRD)等检测手段,揭示MICP技术处理锌铅重金属污染土的修复机制。研究结果表明,采用MICP技术对锌铅重金属污染土进行固化/稳定化之后,可以有效降低污染土中有害重金属的浸出性。当矿化时间为10d时,试样无侧限抗压强度为942.5k Pa;铅的浸出浓度为4.20mg/L,比未处理时降低了44.81%;锌的浸出浓度为4.31mg/L,比未处理时降低了46.19%,效果显著。在此基础上,添加10%的多孔硅吸附材料后,试样无侧限抗压强度可达到1 021 kPa,强度提高了8.3%;铅的浸出浓度为2.45mg/L,与未经处理时相比,降幅达到了67.81%,与单纯MICP方法处理时相比,铅浸出浓度被二次降低了41.67%;锌的浸出浓度仅为2.93 mg/L,与未经处理时相比,降幅达到了63.4%,与单纯...  相似文献   

粉质黏土水泥土冻胀融沉特性研究   总被引：2，自引：2，他引：0  

李思齐  杨平  张婷  鲍俊安 《冰川冻土》2021,43(4):1102-1110

为研究水泥土冻胀融沉特性,对南京地区典型粉质黏土进行了不同条件下的冻胀融沉试验。试验控制因素包括水泥掺入比、含水率、龄期、冷端温度和荷载等,各控制因素在包含基准数值的区间内选取代表性条件进行单一变量试验。试验采用自制冻胀融沉仪进行,冻胀融沉仪下部为制冷块,上部设置补水装置,模拟真实土体冻结时水分迁移过程。结果表明：粉质黏土水泥土冻胀率随水泥掺入比增大、龄期增加呈指数规律减小,随含水率增大、冷端温度升高和荷载减小呈线性增大;融沉系数随水泥掺入比变化规律与冻胀率类似,同一条件下融沉系数均大于冻胀率;水泥土完成融沉的时间随解冻温度升高而减少,但最终融沉系数相同;冻胀融沉存在合理水泥掺入比,粉质黏土的合理水泥掺入比为10%,此时冻胀率为1.56%,融沉系数为2.15%。据此提出,冻结法施工时,预先在土体中按合理水泥掺入比掺入水泥,既可有效抑制土体冻胀融沉,又可提高施工效率。  相似文献