【作者】 刘伟；

【导师】 刘海松； 朱再宜；

【作者基本信息】 长安大学 ， 地质工程（专业学位）， 2019， 硕士

【摘要】 灰土垫层在黄土地区是一种经济有效的地基处理手段,灰土不仅可以消除黄土地层的湿陷性,还可以减少地基的压缩性、降低地基的透水性,进而达到提高地基承载力、降低地基沉降变形,满足建筑物稳定及安全使用的目的。通过室内试验,得出不同灰比的灰土工程性能存在一定的差异,而工程性能的改变与养护时间关系较大。三种灰比(1:9、2:8、3:7)的灰土随养护时间的延长表现出的工程性能具体表现为:1)总体上不同灰比灰土的无侧限抗压强度随养护时间的延长而增长,同时这种强度增长的速率在养护期较短时和较长时也不相同;在养护期一个月内,1:9灰土的无侧限抗压强度增长迅速,超过2:8灰土和3:7灰土,随着养护时间的延长,其增长速度迅速减小;养护一个月时的无侧限抗压强度值接近养护一周时的两倍;在养护期两个月内,2:8及3:7灰土无侧限抗压强度增长迅速,后期3:7灰土强度增长速度大于2:8灰土。2)三种灰比的灰土随养护时间的延长,其压缩模量逐渐增大,同时在低压力阶段(最大0.4MPa)和高压力阶段(3.2MPa)所计算的压缩模量也不相同。高压力阶段计算的压缩模量普遍大于低压力阶段的压缩模量。3)具有相同压实系数的三种灰比的灰土,处理黄土的湿陷性能力相当。4)随着灰土养护时间的延长,抗剪强度增大,剪切破坏形式逐渐由塑性破坏至脆性破坏,灰土的粘聚力和内摩擦角逐渐增大,且在前期增幅速度较快,后期基本不变。5)在干养护条件下,灰土的渗透性会随养护时间的延长而变差,且对水的敏感性降低。总体上2:8灰土对水的敏感性较小,1:9、2:8灰土在养护时间较短时的软化系数较小,水稳性差,随着养护时间延长而逐渐形成水稳定性。6)灰土强度的增长可以分为两个阶段,前期阶段以灰土中的离子化反应、离子交换-水胶连接作用起主导作用,此阶段灰土的强度增长较快,后期阶段以固结反应为主导,固结反应所增加的灰土强度增长速度缓慢,但这种反应增加的强度具有长期稳定性,不易受到外力破坏,对水也具有相对稳定性更多还原

【Abstract】 The lime soil cushion is an economical and effective foundation treatment method in the loess area.The lime soil can not only eliminate the collapsibility of the loess layer,but also reduce the compressibility of the foundation and reduce the water permeability of the foundation,thereby improving the bearing capacity of the foundation and reducing the foundation.Settlement deformation to meet the purpose of stable and safe use of buildings.Through laboratory tests,it is concluded that there are some differences in the performance of lime soil with different gray ratios,and the change of engineering performance has a great relationship with the curing time.The performance of the three types of gray ratio(1:9,2:8,3:7)with the extension of the curing time is as follows:1)In general,the unconfined compressive strength of different gray-to-ash soils increases with the prolongation of curing time,and the rate of such strength increase is also different when the curing period is shorter and longer;within one month of the curing period The unconfined compressive strength of 1:9 lime soil increases rapidly,exceeding 2:8 lime soil and 3:7 lime soil.With the extension of curing time,its growth rate decreases rapidly;the unconfined compression resistance at one month of curing The intensity value is nearly twice that of the one-week maintenance period;in the two months of the curing period,the unconfined compressive strength of the 2:8 and 3:7 lime soils increases rapidly,and the growth rate of the later 3:7 lime soil is greater than the 2:8 lime soil.2)The lime-soil ratio of the three gray ratios increases with the curing time,and the compressive modulus is also different in the low pressure stage(maximum 0.4MPa)and the high pressure stage(3.2MPa).The compressive modulus calculated at the high pressure stage is generally greater than the compressive modulus at the low pressure stage.3)Three kinds of gray ratios of lime soil with the same compaction coefficient,the collapsibility of the treated loess is equivalent.4)With the prolonging of the curing time of lime soil,the shear strength increases,the shear failure form gradually changes from plastic to brittle,and the cohesive force and internal friction angle of the lime soil gradually increase,and the growth rate is faster in the early stage.Basically unchanged.5)Under dry curing conditions,the permeability of the lime soil will deteriorate with the extension of the curing time,and the sensitivity to water will decrease.In general,the sensitivity of 2:8 lime soil to water is small.The softening coefficient of 1:9 and 2:8 lime soil is small when the curing time is short,the water stability is poor,and the water stability gradually forms with the curing time.6)The growth of lime soil strength can be divided into two stages.In the early stage,the ionization reaction in the lime soil and the ion exchange-water gel linkage play a leading role.At this stage,the strength of the lime soil increases rapidly,and the consolidation reaction in the later stage is Leading,the increase of the strength of the lime soil increased by the consolidation reaction is slow,but the increased strength of this reaction has long-term stability,is not easily damaged by external forces,and is relatively stable to water.更多还原