新型无熟料碱渣固化土的工程特性

以碱渣、矿渣、粉煤灰等固体废弃物为主要原材料,并掺入适量脱硫石膏及少量复配激发剂,配制新型无熟料碱渣固化剂.该新型无熟料碱渣固化剂物理力学性能基本满足P·C325复合水泥技术要求.将新型无熟料碱渣固化剂或复合水泥(P·C325)按不同掺比（质量比）掺入土中,制成新型无熟料碱渣固化土或复合水泥固化土,然后分析对比新型无熟料碱渣固化土与复合水泥固化土的14,28,90d无侧限抗压强度、抗拉强度、压缩性能、抗剪性能等工程特性,结果表明:新型无熟料碱渣固化剂掺比20%的固化土工程特性基本与复合水泥掺比10%左右的固化土相当.     

建筑垃圾渣土制备固化土配合比参数研究

以无机固化剂与离子类固化剂联合固化渣土,使用三角等焓图分析固化土性能与配合比参数之间的关系,结果表明,固化土无侧限抗压强度及抗冻性均随离子类固化剂掺量的增加而提高;无侧限抗压强度及抗冻性在三角等焓图上的梯度方向与水泥掺量一致,表明水泥是影响固化土强度及抗冻性的关键因素;石灰对固化土强度的影响表现为早期强度低,土体强度较高时石灰对强度的影响较小;渣土级配对固化土性能的影响存在最佳区间,建议渣土中颗粒级配为(0-5mm)∶(5～10mm)∶(10-25mm)=40％∶20％∶40％或50％∶40％∶10％.     

复合固化剂改良地铁渣土的无侧限抗压强度研究

为了解决地铁盾构施工中产生的大量工程渣土的再利用问题,本文选择水泥、粉煤灰、高分子聚合物A作为一种复合固化剂来改良地铁渣土。探讨复合固化剂对改良后的地铁渣土无侧限抗压强度变化规律,探究地铁渣土含水率、复合固化剂掺量、龄期对固化土强度的影响,并得出强度拟合公式。试验结果表明:在相同掺量、相同龄期的条件下,复合固化土7d无侧限抗压强度为水泥固化土的2.32～2.91倍,复合固化土180d无侧限抗压强度为水泥固化土2.32～4.37倍,复合固化剂较水泥固化剂具有显著的力学性能优化作用。     

ISS—水泥联合固化淤泥的微观机理研究

采用离子土固化剂(ISS)、水泥、碱化剂NaOH对福建宁德海相淤泥进行单掺、复掺、碱化复掺等不同方式的化学固化。在对固化前后的淤泥样品开展无侧限抗压强度、24h固结压缩等力学试验的基础上,通过SEM、XRD、XRF等微观测试,分析不同固化方式下淤泥的固化效果;研究不同形态酸、碱固化剂相互作用的定性和定量关系;探讨ISS—水泥联合固化淤泥的微观机理。试验结果表明:在相同水泥掺量下,NaOH碱化ISS—水泥联合固化淤泥效果优于单掺水泥固化淤泥效果,且二者都好于酸性ISS—水泥联合固化淤泥的效果。     

水泥-赤泥-粉煤灰稳定土固化剂力学性能研究

试验研究了由赤泥、粉煤灰和水泥组成的稳定土固化剂的配比、物理力学性能及其对工程渣土固化效果和无侧限抗压强度的影响规律,利用X射线衍射(XRD)和扫描电镜(SEM)表征了水泥-赤泥-粉煤灰稳定土固化剂的矿物组成和微观形貌,分析了稳定土固化剂的作用机理.试验结果表明,固化剂中水泥用量固定时,其胶砂试样的强度随着赤泥掺量的增...     

不同物态配比碱渣-粉煤灰混合料强度特性

为改善传统碱渣土填筑方法工艺复杂、耗时较长的缺点,以山东海化集团的碱渣和粉煤灰为原材料,对不同物态和配比的碱渣土进行了室外填筑试验,并通过室内试验对液相填筑碱渣土的均匀性和强度进行改良。采用击实试验、轻型动力触探试验、便携式可变能量动力触探试验对现场填筑碱渣土的强度特性进行测试表征;采用自制的沉淀器模拟液相碱渣土的一维固结沉降,对液相填筑碱渣土的均匀性和强度进行改良和测试。结果表明,碱渣与粉煤灰固体的最优质量配比为7∶3,其最大干密度和最优含水率分别为0.88 g/cm~3,64%。碱渣土液相填筑具有可行性,且液相填筑碱渣土的土体强度及均匀性明显优于液相-固相填筑的碱渣土。液相填筑的碱渣土存在一定的分层现象,电离子土壤固化剂能进一步提高土体均匀性,其最优掺量为0.019%。在碱渣土中掺入7%的石灰粉能有效激发粉煤灰活性,大幅提高碱渣土的承载能力。试验结果可指导碱渣土的填筑施工,进一步提高碱渣土的填筑效率和质量。     

水泥固化锌污染黏土的压缩特性试验研究

通过压缩试验对不同水泥掺量、不同锌离子浓度的水泥固化污染土的压缩特性进行研究,分析水泥固化锌污染土的固结屈服应力py'、压缩指数Cc与水泥掺量和锌离子浓度的关系;引入评价天然重塑黏土固有压缩特性的孔隙指数Iv,对压缩试验结果进行正规化处理,进一步探讨不同水泥掺量下不同锌离子浓度污染土的压缩特性。结果表明,锌离子浓度对于水泥固化污染土的压缩特性和结构性具有显著影响。锌离子浓度越高,水泥固化锌污染土的结构性越差,固结屈服应力py'和压缩指数Cc越低。     

水泥基流态土固化剂的试验研究

为制备性能优良水泥基流态土固化剂,通过研究水泥基流态土固化剂中拌合用水与回填土的比例、固化剂掺量与回填土质量的比例和水泥基流态土固化剂的组成,确定水泥基流态土固化剂的最佳掺量,探讨增强固化土抗压强度的方法。采用扫描电子显微镜(SEM)观测水泥基流态土固化剂的微观结构和水化产物,分析水泥基流态土固化剂的加固机理。研究表明,在一定钢渣的情况下,选择硫酸钠(掺量4%)作为碱激发剂材料,调整合适比例的水泥-矿粉产生饱和Ca(OH)2,可保证强度有效增长。钙矾石膨胀填充固化土中的孔隙是提高固化土强度的主要因素。     

基于扰动状态概念理论的固化淤泥一维压缩模型

采用低碳、环保的镁质水泥对淤泥进行固化处理,研究了不同龄期下固化淤泥一维压缩特性。采用新型环刀制样方法,开展了镁质水泥固化淤泥的一维压缩实验研究。结果表明:固化淤泥的压缩曲线与结构性土变化趋势类似,固化淤泥的ln(1+e)–lgσ′v曲线存在一个明显的拐点(结构屈服应力),且随着龄期的增长,固化淤泥的结构屈服应力逐渐增大。基于扰动状态概念理论,提出了能反应固化淤泥强化与弱化并存的一维压缩模型,试验验证了该模型可以较好预测任意龄期下固化淤泥的一维压缩特性。     

碱渣资源化利用的工程性质试验研究

随着环境保护和废物资源化利用要求的提高,在碱渣中混合一定比例的粉煤灰制成碱渣土,并应用于工程中,成为碱渣利用的最有效途径之一.通过微型触探试验、硬化时间测试、室内击实试验、比重试验和室外静载试验,对不同配比碱渣土的工程性能进行了试验研究,并得出了相应的结论.结果表明,一定配合比下的碱渣土可应用于地基、路基以及场地的填筑.     

碱渣土强度和变形的室内试验研究

进行了不同配比碱渣土的室内力学性能试验,试验结果表明加入钢渣、分砂后提高了碱渣土的抗剪强度,减小了其压缩性,而加石灰的碱渣士的无侧限抗压强度大幅提高。     

碱渣压缩变形特性

通过碱渣的压缩试验 ,研究了击实碱渣的压缩变形性质 ,讨论和分析了击实碱渣在不同压力区间的压缩系数及压缩模量的数值分布规律和固结系数的数值变化规律     

碱厂白泥作为填埋场衬层防渗土料的探索研究

首先分别对白泥和在青岛2个填埋场取回的2种粘土防渗土料(风化土和亚粘土)的压实性、抗剪性、渗透性以及收缩性等几个主要的衬层设计指标进行了对比评价,结果表明,白泥具有较差的压实性、良好的抗剪性和抗干裂性,测得其在最优含水率及相近含水率下的击实土样的渗透系数均在10-7cm/s数量级范围内。然后将白泥与2种粘土防渗土料进行复合,形成2种混合式的复合土料(白泥+风化土和白泥+亚粘土)和2个夹层结构复合土料(白泥/风化土和白泥/亚粘土),测试其渗透系数:亚粘土添加量为30%～40%的白泥+亚粘土混合土料以及2个夹层结构复合土料的防渗性能较好,渗透系数都达了10-8cm/s数量级。     

Evaluating the compression index of fibrous peat treated with different binders

Fibrous peats feature high compressibility and correspondingly very low strength. In this study, an investigation into the compressibility of untreated and stabilized fibrous peat with different binders—namely cement, lime, gypsum, and fly ash—is presented. The technique adopted for sample preparation was aimed at simulating the in-situ condition of the deep soil mixing technique. For this purpose, the binder dosages were selected in the range of 100–400 kg/m³ of wet fibrous peat at its natural water content. This binder range was determined based on the unconfined compressive strength of the treated samples. All the treated samples were cured for 14, 28, and 90 days in both air and water. The consolidation behavior of the treated peat samples was assessed by performing a Rowe cell consolidation test. The test results revealed that the increase in cement, fly ash, and gypsum contents led to considerable decreases in compression indices of the treated fibrous peat. No significant changes in the compressibility properties of lime-treated peat were observed. In addition, the inclusion of well-graded sand as filler decreased the compression indices of the treated samples significantly. Finally, in comparison with air curing, the use of the water curing technique for all the stabilized samples, regardless of binder type, showed better performances.     

碱渣土的击实试验

为了指导碱渣土填土施工 ,找出最优配比 ,研究了不同配比碱渣土的击实试验 .试验结果表明 ,加入钢渣的碱渣土的击实效果较好     

Influence of applying overburden stress during curing on the unconfined compressive strength of cement-stabilized clay

In the case of cement-stabilized soils cured under the influence of overburden stress, it is necessary to consider two different timelines of cementation and consolidation, along which the structures of stabilized soils evolve. These two timelines are interrelated and ought not to be considered separately, especially in the early stage of curing when significant structural changes occur. In this study, the strength and deformation characteristics of cement-stabilized clay subjected to overburden stress during curing was investigated using an unconfined compression test apparatus. For this purpose, three types of specimens were prepared by stabilizing very soft clay with different amounts of cement. Overburden stress was applied for three different time durations during curing. In the series of unconfined compression tests conducted on the specimens with no overburden stress applied during curing, the axial stress initially increases rapidly, then was maintained before finally dropping. In the series of tests with overburden stress applied during curing, the axial stress continues to increase gradually before rapidly declining. The values of unconfined compressive strength are larger for the specimens subjected to overburden stress during curing. The values of the unconfined compressive strength also increase linearly as the duration of applied overburden stress increases. The increase in strength apparently occurs due to increasing dry density accompanied by a decrease in the water content due to the drainage of pore water during the application of overburden stress.     

Yielding of cement-treated marine clay

This paper presents the findings of an experimental study on the primary yielding and post-yield behavior of cement-treated Singapore marine clay. The study was conducted using unconfined compression tests and triaxial tests. The results show that all the primary yield loci for the cement-treated marine clay have a consistent shape regardless of the mix ratio, curing stress or curing period. Three relationships are proposed for determining the size of the primary yield locus. The first two involve the direct determination of the isotropic primary yield stress, whereas the third makes use of the unconfined compressive strength. The first two relations are valid only for 7-day specimens. The third appears to have slightly larger scatter, but it is also applicable over a wider range of curing period and curing stress. Post-yield, over-consolidated samples were obtained by compressing specimens isotropically under effective stress levels higher than their isotropic primary yield stress and then allowing them to swell back to a lower effective confining stress prior to shearing. The normalized yield loci of these pre-yielded samples show a “collapse” from steep arches to more-rounded ellipses, while the yield loci expand with isotropic pre-compression pressure.     

软土结构性定量化参数研究

土结构性研究的根本任务是寻找能全面反映土在应力作用下结构破损规律的定量化指标。对黄石、漳州、青岛地区软土进行单向与等向压缩试验,分析结构性土的压缩特性,探讨了不同试验条件对软土结构性的影响,结果表明:当压力低于结构屈服压力时,主要是初始结构的自我调整过程,结构存在少量的破损,压缩性较小;当压力大于结构屈服压力时,结构大量破坏,除了颗粒间的滑移,还伴随结构的塌陷,压缩性大大增加;重塑样在压缩过程中压缩性变化不大,这是由于重塑样已失去了结构性的影响。根据土样在压缩过程中结构破损情况提出了一个新的判别结构性强弱的定量化参数—结构破损系数,该值可通过AutoCAD软件简单获取,便于推广。利用该方法判别试验土样中结构性最强的为青岛软土,黄石软土次之,漳州软土最弱。最后利用结构破损系数解释了不同扰动程度对压缩曲线的影响。     

水泥粉煤灰搅拌桩复合地基的离心模型试验及现场实测效果研究

在水泥桩体中掺入一定量的粉煤灰不仅可以节约资源,还可以增强桩体在酸性地基中的抗腐蚀性能。为了研究水泥粉煤灰搅拌桩处治饱和黄土地基的适用性,以蒲渭高速公路为工程依托,以水泥与粉煤灰不同重量比组成的固化剂及其不同掺入比配制的试件进行的无侧限抗压强度试验、直剪试验和固结压缩试验为基础,选择最佳配比后进行水泥粉煤灰搅拌桩的离心模型试验,并与现场实测结果相对比。结果表明:当水泥与粉煤灰的重量比不小于2∶1时,粉煤灰的添加对试件的抗剪强度影响不大;固化剂掺入比达到15%以后,水泥粉煤灰土与水泥土试件的强度相差值减小;离心模型试验所得工后沉降量小于0.3m;现场实测工后沉降量和桩体强度均符合设计要求。水泥粉煤灰搅拌桩处理饱和黄土地基是经济可靠的。