固化疏浚淤泥—磷石膏混合土工程性质及膨胀特性研究

发布时间：2018-06-07 10:13

本文选题：疏浚淤泥 + 磷石膏　；参考：《昆明理工大学》2013年博士论文

【摘要】：固化疏浚淤泥-磷石膏混合土是以疏浚淤泥/磷石膏混合物为基质土,通过添加水泥(石灰)将基质土固化为填土材料的一项新技术,以期实现疏浚淤泥、磷石膏两种废弃物的资源化利用。作为一项新型的废弃物资源化处理技术,需要对固化混合土的工程性质进行系统研究,以发展和完善混合料固化处理技术。本文通过无侧限抗压强度试验、直剪试验、固结试验、渗透试验、线性膨胀率检测等一系列室内试验,主要研究了基质土中疏浚淤泥/磷石膏的合理混合比、疏浚淤泥初始含水率、养护龄期、不同固化剂及其掺量等不同因素对固化混合土工程性质的影响；探讨了固化土重塑土工程性质、重塑时机、及其强度折减、恢复机理；初步揭示了膨胀性变化规律及其对固化混合土固化效果的影响,并对固化混合土的膨胀机理进行了分析。固化混合土工程性质研究：(1)影响固化混合土的强度、压缩特性、含水率以及渗透系数的主要因素有：基质土中疏浚淤泥磷石膏混合比、疏浚淤泥初始含水率、养护龄期、固化剂及其掺量。在此基础上提出了固化混合土强度变化与磷石膏掺量的关系模型,该模型把强度随磷石膏掺量的变化分为三个阶段：强度增长阶段；强度降低阶段；强度稳定阶段。(2)相比单一疏浚淤泥固化,固化混合土具有更好的固化效果,可以节省固化剂的掺量；其破坏应变大于单一固化淤泥土,具有较好的韧性和工程适用性。(3)固化疏浚淤泥磷石膏混合土技术是可行的,可以实现同时大量消纳疏浚淤泥、磷石膏两种固体废弃物,且固化成本不高。固化土的重塑特性研究：(1)固化淤泥土、固化混合土的重塑土重塑时强度会发生显著的折减,养护后强度会得到一定程度的恢复。重塑时机是影响强度折减、恢复的最重要因素,其它影响因素还有基质土疏浚淤泥与磷石膏配比、固化剂及其掺量、重塑后养护龄期等。(2)从机理上看,重塑土强度折减主要由于破碎过程对粘聚力的破坏,强度恢复则来源于粘聚力和内摩擦角的增长。固化淤泥重塑土的强度恢复是颗粒摩擦咬合力的增加、凝胶的修复两者共同作用的结果,重塑时机是影响重塑后凝胶修复作用大小的重要因素；而固化混合土重塑土的强度恢复是颗粒摩擦咬合力的增加、凝胶的修复以及胀损三者协同作用的结果,重塑时机是影响三者协调性的重要因素。(3)相比原固化混合土,其重塑土具有更好的压缩特性、更小的渗透系数。(4)重塑土具有较好的工程性质,采用固化土的重塑土作为土方填料是可行的,并分别探讨了固化淤泥土以及固化混合土的最佳重塑时机。固化混合土的膨胀特性研究：(1)固化混合土基本上都具有一定的膨胀性,整体来看膨胀性提高了固化混合土的密实度,对固化混合土是有益的。实验结果表明,线性膨胀率与疏浚淤泥初始含水率、固化剂掺量、疏浚淤泥与磷石膏的配比,养护时间等因素有关,并给出了线性膨胀率随各因素变化规律。(2)机理分析发现,固化混合土水分转化分为三步,水分转化对固化混合土自生体积稳定性,强度影响较大；固化混合土的宏观体积是收缩和膨胀共同作用的结果,宏观强度是膨胀损伤和凝胶修复共同作用的结果。(3)提出了对固化混合土膨胀性设定判断标准,根据前人标准判断,固化混合土的膨胀程度基本上属于微膨胀或中度膨胀,具有较好的工程适用性。
[Abstract]:The solidified dredged silt - phosphogypsum mixed soil is a new technology that uses the dredged silt / phosphogypsum mixture as the matrix soil and solidified the matrix soil into the filling material by adding cement (lime), in order to realize the dredging silt and the resource utilization of two kinds of phosphogypsum. The engineering properties of the mixed soil are systematically studied in order to develop and perfect the solidification treatment technology of the mixture.
In this paper, a series of laboratory tests, such as unconfined compression strength test, direct shear test, consolidation test, permeability test, linear expansion rate testing, are used to study the reasonable mixing ratio of dredged silt / phosphogypsum in matrix soil, the initial water content of dredged silt, curing age, and different factors such as curing agent and its content. The effect of process properties, the engineering properties of the remolded soil, the time of remolding, the strength reduction and the recovery mechanism are discussed, and the regularity of the expansibility and its effect on the curing effect of the cured mixed soil are preliminarily revealed, and the expansion mechanism of the cured mixed soil is analyzed.
Study on the engineering properties of solidified mixed soil: (1) the main factors affecting the strength, compression properties, moisture content and permeability coefficient of the solidified mixed soil include the mixing ratio of dredged silt and phosphogypsum, the initial water content of dredged silt, curing age, curing agent and its content. On this basis, the strength changes of the solidified soil and the phosphorus stone are put forward. The relationship model of paste content is divided into three stages: the strength increase stage, the strength decrease stage, the strength decrease stage, the strength stable stage. (2) the solidified soil has better curing effect compared with the single dredged silt, and it can save the dosage of the solidifying agent; the damage strain is greater than the single solidifying silt. Soil has good toughness and engineering applicability. (3) it is feasible to solidify dredged silt phosphogypsum mixed soil technology, and can achieve a large amount of dredging silt, two kinds of phosphogypsum solid waste at the same time, and the curing cost is not high.
Study on the remolding characteristics of solidified soil: (1) solidify silt soil, the strength of the remolded soil of the solidified soil will be significantly reduced and the strength will be restored to a certain extent after curing. The time of remolding is the most important factor affecting the strength reduction and recovery, and the other factors are the ratio of matrix soil dredged silt and phosphogypsum, and the curing agent. And its content, remolded curing age, etc. (2) from the mechanism, the strength reduction of remolded soil is mainly due to the destruction of the cohesive force in the crushing process, and the strength recovery comes from the increase of cohesion and internal friction angle. The strength recovery of the remolded soil of the solidified mud is the increase of the particle friction bite force, and the result of the joint action of the gel repair is heavy. The plastic time is an important factor affecting the remolding effect of the remolded gel, and the strength recovery of the remolded soil of the solidified soil is the increase of the particle friction and bite force, the repair of the gel and the synergistic effect of the three parts of the swelling, and the time of remolding is an important factor affecting the coordination of the three. (3) compared with the original solidified soil, the remolded soil has a remolded soil. Better compression characteristics and smaller permeability coefficient. (4) the remolded soil has better engineering properties, and the remolded soil of the solidified soil is practicable as a earthwork filler, and the best time to remould the solidified silt and solidified soil is discussed respectively.
Study on the swelling characteristics of solidified mixed soil: (1) the solidified mixed soil has a certain expansibility basically. In the whole, the expansibility improves the density of the solidified soil and is beneficial to the solidified mixed soil. The experimental results show that the linear expansion rate and the initial water content of dredged silt, the dosage of the curing agent, the ratio of the dredged silt to the phosphogypsum, The linear expansion rate varies with each factor. (2) the mechanism analysis shows that the water conversion of the solidified mixed soil is divided into three steps. The water transformation has a great influence on the stability of the spontaneous volume of the solidified soil and the strength of the soil; the macroscopic volume of the solidified mixed soil is the result of the joint action of shrinkage and expansion and the macroscopic strength. It is the result of the joint effect of expansion damage and gel repair. (3) a criterion for determining the expansibility of the solidified mixed soil is put forward. According to the previous standards, the expansion degree of the solidified mixed soil is basically of micro expansion or medium expansion, which has good engineering applicability.
【学位授予单位】：昆明理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU449

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