含工业废料加固土的特性研究

工业废料粉煤灰中掺适量水泥或石灰等固化剂来加固土壤,不仅可以降低工程造价、改善环境,而且可以增加加固土体的强度,使之能应用于工程实践。参考了大量国内外文献资料后,对粉煤灰、炉渣等工业废料在岩土工程领域中的运用背景及作用机理等作了探讨,并以大量的试验进行了初步的研究,得出不同胶凝材料、不同掺量对不同复合土强度的影响规律。     

深层搅拌桩新型胶结材料的试验研究

介绍了一种利用工业废料加工的深层搅拌桩新型土体胶结剂,并将工业废料加固土的无侧限抗压强度、渗透系数、压缩模量、三轴抗剪强度的试验结果以及静载荷试验结果与水泥加固土进行了对比分析,结果发现：工业废料加固土与水泥加固土具有同样的工程性质。另外,还给出了工业废料加固土无侧限抗压强度随时间增长的关系表达式,他工业放心料胶结料加固软基的机理。     

粉煤灰炉渣加固土的室内无侧限抗压强度试验研究(英文)

给出了用粉煤灰、炉渣等工业废料加固土的室内无侧限抗压强度试验结果,分析了加固土无侧限抗压强度与外加剂掺量、养护龄期之间的影响规律,得出了针对不同工业废料加固土所用外加剂的最佳掺量。     

搅拌桩用工业废料胶结剂的实验室研究

对比了工业废料胶结剂加固土与425普通硅酸盐水泥加固土的无侧限抗压强度试验、压缩固结试验和渗透试验的结果,以验证工业废料胶结剂代替普通水泥的可行性．同时,对无侧限抗压强度的影响因素进行了分析,并给出了相应的关系表达式。     

粉煤灰的综合应用与开发

对粉煤灰的运用背景及作用机理等方面作了初步探讨，阐述了粉煤灰在其他方面的应用，指出工业废料粉煤灰中掺适量水泥或石灰等固化剂来加固土壤，不仅可以降低工程造价、改善环境，而且可以增加加固土体的强度。     

工业废料合成固化剂加固土的室内试验研究

利用工业废料加固地基具有较好的技术经济效益和社会效益，本文概要介绍水泥-粉煤灰、水泥-磷石膏固化剂加固土的室内试验研究。     

搅拌桩用的工业废料胶结剂

以工业废料零号钢渣、高钙粉煤灰、混合灰等为主要原料,用氟石膏作为激发剂,采用球磨工艺进行深加工制成的新型土体胶结剂,用作深层搅拌桩的土体胶结料,其物理、力学性能完全可以取代普通硅酸盐水泥。研究结果表明,工业废料胶结剂用于加固土壤能极大提高原状土的强度,改善原状土的变形性能,比相同条件下强度等级 32.5普通水泥用于加固土的效果有较大提高;并且比普通水泥更能适应各种诸如含水量偏高、土质较差的工程条件,它能以较低的掺入量 (9％ )达到甚至超过普通水泥较高掺入量 (15％ )时的加固效果。工业废料胶结剂在废物的综合利用及降低深层搅拌桩造价方面,可取得社会和经济的双重效益。     

水泥加固酸污染土无侧限强度特征

污染土是利用水泥固化处理后,土体的强度得到提高。针对该项技术,采用水泥固化法处理酸污染土,通过两种试验方案,对水泥加固酸污染土的无侧限抗压强度特性进行研究。试验所用酸污染土用浓硫酸配置人工制备而成,并考虑了不同水泥掺量、不同硫酸浓度和不同龄期对水泥加固酸污染土强度的影响。试验表明:水泥固化酸污染土的强度与水泥掺量和硫酸含量有密切关系,二者共同作用决定其强度的变化。在一定硫酸浓度(2~16g/kg)条件下,伴随硫酸含量的升高,水泥掺量较低时,无侧限抗压强度整体呈明显下降的趋势;水泥掺量较高时,无侧限抗压强度呈缓慢上升的趋势。随着水泥掺量提高,土样的无侧限抗压强度达到峰值时所对应的硫酸含量也逐渐变大。     

工业废石膏与水泥配合加固软土地基

利用工业废石膏与水泥配合加固软土地基,与单用水泥加固相比,加固土强度可成倍提高。废石膏的最佳掺量一般为水泥用量的20％ 左右。用废石膏－水泥加固时,其水化物中仅有水化硅酸钙将松散的土粒胶 结成整体,而且还产生大量钙矾石,其晶体膨胀填充孔隙,使加固土强度进一步提高。     

广州南沙地区软土采用水泥和粉煤灰固化试验研究

通过室内试验,研究广州市南沙地区软土采用水泥和粉煤灰加固力学特性。考虑水灰比、水泥粉煤灰混合固化剂掺量、粉煤灰掺量的变化对固化土无侧限抗压强度的影响,建立固化土强度-龄期一系列函数公式。研究显示:水泥起到提高固化土强度的主要作用,粉煤灰的掺量应有所限制;对于不同的混合固化剂配比,有各自的最佳水灰比。水灰比小于0.5,加大混合固化剂掺量不能显著提高固化土强度。广州南沙软土采用水泥粉煤灰搅拌桩加固,混合固化剂掺量取15%~18%,粉煤灰掺量取20%~30%,水灰比取0.53左右,比较合理。     

冻融对固化钻井泥浆强度及重金属浸出量影响

在石油钻井过程中会产生大量含重金属废弃钻井泥浆,对环境污染很大,需进行无害化处理。本研究采用水泥和工业废渣固化废弃钻井泥浆,经过不同次数的冻融循环后,测试固化土强度、固化土中Pb²⁺离子和Cr⁶⁺离子的浸出量以及固化土中的孔隙变化规律,探讨工业废渣固化废弃钻井泥浆的抗冻性能。结果表明:固化土试件的强度均随着冻融循环次数的增加而下降;固化剂组分中工业废渣的掺量增加,特别是磷石膏掺量增加能够有效的减弱固化土在冻融循环作用下的强度损失。工业废渣能够有效的稳定固化土中的Pb²⁺离子和Cr⁶⁺离子,浸出量比水泥固化土降低70%~80%。对固化土孔隙的测试结果证实由工业废渣固化的固化土试件的密实度大于仅由水泥固化的试件。     

工业废料胶结剂加固土与普通水泥加固土的对比试验研究

工业废料胶结剂是指一种利用工业废料加工而成的用于深层搅拌桩的新型土体胶结剂.本文主要讨论并对比了工业废料胶结剂加固土与425号普通硅酸盐水泥土的无侧限抗压强度试验,以验证工业废料胶结剂代替普通水泥的可行性.同时,对无侧限抗压强度的影响因素进行了分析,并给出了相应的关系表达式.     

烧碱激发钢渣粉在淤泥质土中的试验研究

钢渣粉是炼钢生产后排出的工业废渣经球磨后形成的一种粉末状产物,与水泥有着相似的性质,但活性较差,需对其进行激发处理。将烧碱(Na OH)作为钢渣粉的激发剂,研究在不同烧碱掺入量下,钢渣粉与水泥混合后对淤泥质土的固化效果。试验结果表明:未掺烧碱的钢渣–水泥固化土早期强度低,后期固化效果较好;掺入烧碱之后,在其激发作用下,钢渣粉的固化效果良好且可使固化土早强。钢渣–水泥固化土的无侧限抗压强度随着烧碱掺量的增加而出现先增大后减小的变化。对胶凝材料进行X射线衍射(XRD)分析,发现材料中有单硫型硫铝酸钙(AFm)物质生成,该物质可提高固化土的强度。     

Mechanical behavior of lightweight soil reinforced with waste fishing net

Lightweight soil is cement-treated and consists of dredged clayey soil, cement, and air-foam. Reinforced lightweight soil (RLS) contains waste fishing net to increase its shear strength. This paper investigates the strength characteristics and stress–strain behavior of reinforced and unreinforced lightweight soils. Test specimens were prepared with varying admixtures of cement content (8%, 12%, 16%, and 20% by the weight of untreated soil), initial water content (125%, 156%, 187%, 217%, and 250%), air-foam content (1%, 2%, 3%, 4%, and 5%), and waste fishing net (0%, 0.25%, 0.5%, 0.75%, and 1%). Then several series of unconfined compression tests and one-dimensional compression tests were conducted. The experiments with lightweight soil indicated that the unconfined compressive strength increased with an increase in cement content, but decreased with increasing water content and air-foam content. The stress–strain relationship and the unconfined compressive strength were influenced by the percentage of waste fishing net. In addition, the strength of RLS generally increased after adding waste fishing net due to the bond strength and the friction at the interface between waste fishing net and soil mixtures, but the amount of increase in compressive strength was not directly proportional to the percentage of waste fishing net. The results of testing indicated that the maximum increase in compressive strength was obtained for a waste fishing net content of about 0.25%. The bulk unit weight of lightweight soil was strongly dependent on the air-foam content. The compression characteristics of lightweight soil, including the yield stress and compression index, did not depend greatly on whether the samples were cured underwater or in air.     

水泥土强度对型钢水泥土组合梁的影响研究

型钢水泥土搅拌墙在基坑工程中有着广泛的应用,因为没有充分了解水泥土在搅拌墙中起到的作用,水泥土的刚度仅被作为安全储备,这无疑造成一定的浪费。为了研究水泥土强度对搅拌墙的影响,本文以水泥土强度为变量设计了系列双型钢水泥土组合梁试验,采用分布式光纤采集试验梁加载过程的应变数据,提出了针对H型钢的分布式光纤应变数据的处理方法。通过对实验数据的处理和分析,得到了水泥土强度对组合梁挠度、刚度的影响规律,以及型钢与水泥土对组合梁外部荷载的分担情况。本文对型钢水泥土搅拌墙的理论研究与实际应用有一定的参考价值。     

Effects of industrial by-product based geopolymers on the strength development of a soft soil

Portland cement is traditionally used as a binder in ground improvement projects on soft soil foundations. The use of cement in ground improvement projects, however, is fraught with both, financial and environmental concerns due to its relatively high cost, the use of natural resources and the high carbon footprint from cement production. Attempts are being made to find alternative environmentally friendly binders with a low carbon footprint using industrial by-products such as fly ash (FA) and slag (S). Using waste by-products such as FA and S to produce geopolymer binders, as novel green cementitious materials, may provide an environmentally friendly and effective ground improvement option. In this study, the effect of adding geopolymers to a soft soil was investigated for usage in deep soil mixing (DSM) applications. The soil was a soft marine clay known as Coode Island Silt (CIS). Different combinations of FA and S with six combinations of sodium and potassium based liquid alkaline activators (L) were added to the soil to study the effects on its engineering and chemical properties. These changes were evaluated via an unconfined compression strength (UCS) test, scanning electron microscopy (SEM) imaging and energy-dispersive X-ray spectroscopy (EDS) tests. The tests were conducted after 3, 7, 14 and 28?days of curing. Based on the results, the important role of L in strength development was studied, and the combination of 30% NaOH with 70% Na₂SiO₃ was found to achieve the highest strengths. Furthermore, increasing the S content was found to result in significant improvements in strength. The excellent correlation between strength and stiffness shown in the results are expected to help in the development of relationships for strength prediction of these green binders in geotechnical applications. This study shows that FA and S based geopolymers can be used as sustainable binders in DSM projects, with significant environmental benefits.     

腐蚀性场地形成的水泥土的劣化研究

水泥土等加固体的劣化可以分为场地环境变化引起已有加固体的劣化问题和在腐蚀性场地形成的加固体的劣化问题。前一个问题是加固体形成一段时间后因外界环境变化而受到侵蚀的问题;后者是加固体在腐蚀性环境中产生强度的同时发生劣化的问题。为了研究加固体在腐蚀性场地的劣化问题,开发了一种能够近似模拟加固体形成环境的养护装置。在试样筒中制备加固体后立即将加固体连同试样筒置于养护筒,并只允许加固体顶面与腐蚀性环境接触,达到一定龄期后实施微型贯入试验及化学成分分析试验,初步研究了海水及其压力对滨海沉积软土场地形成的水泥土劣化的影响。结果表明：海水环境下水泥土的劣化进展较快;劣化深度有随水压力增大的趋势;劣化的发生与 Ca ²⁺ 的溶出有关, Ca ²⁺ 浓度随水泥土深度的变化趋势呈现一定的规律性。