火山灰改良粗粒硫酸盐渍土路基填料及其作用机理研究
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摘要
针对硫酸钠含量为2%的砾砂类硫酸盐渍土,开展了在不同石灰配比、石灰+火山灰配比工况下的击实试验、盐胀试验、溶陷试验、无侧限抗压强度试验,在此基础上,分析了其改良机理和微观特性,结果表明:掺加石灰或石灰+火山灰改良剂不仅可以有效减少砾砂类硫酸盐渍土的盐胀量,而且可以降低盐胀敏感温度区间;在采用无机改良剂改善硫酸盐渍土的盐胀变形时,应结合当地气候条件考虑,在温度较高地区可以适当减少改良剂掺量,温度较低时,适当增加改良剂掺量;相比于石灰改良土,掺加火山灰后,土样的压密阶段缩短,弹性阶段增长,土样达到强度极限时产生的应变减小,土体的结构性变强,抗变形性能增强;添加火山灰对于此类盐渍土的强度增长速率亦有加速作用;采用石灰掺量高于11%时或采用石灰+火山灰不少于15%时,改良后土体的盐胀和溶陷变形率均小于1%,7 d饱和无侧限抗压强度均不小于0.35 MPa。
For the gravelly sand type sulfate soil with sodium sulfate content of 2%, the compaction tests, salt expansion tests,collapsibility tests and unconfined compressive strength tests with different ratios of lime, lime + volcanic ash are carried out.Based on these tests, the improved mechanism and micro-characteristics are analyzed. The results show that adding lime or lime+ volcanic ash can reduce the salt expansion effectively and reduce the sensitive temperature range of salt expansion. In the case of using inorganic modifiers to improve the salt expansion deformation of the sulfate saline soil, considering the local climatic conditions, the amount of modifiers can be appropriately reduced in the areas with higher temperature, and when the temperature is lower, the amount of modifiers should be appropriately increased. Compared to that of the lime-improved soil,the compaction stage of the volcanic ash-improved soil is shortened, the elastic stage is increased, the generated strain when the soil sample reaches the strength limit is reduced, the soil structure is stronger, and the deformation resistance is enhanced. The addition of volcanic ash can also accelerate the strength growth rate of such saline soils. The deformation rate of salt expansion and collapsibility are both less than 1% by adding lime higher than 11% or lime +volcanic ash not less than 15%, and the 7-day saturated unconfined compressive strength of the improved soil is not less than 0.35 MPa.
For the gravelly sand type sulfate soil with sodium sulfate content of 2%, the compaction tests, salt expansion tests,collapsibility tests and unconfined compressive strength tests with different ratios of lime, lime + volcanic ash are carried out.Based on these tests, the improved mechanism and micro-characteristics are analyzed. The results show that adding lime or lime+ volcanic ash can reduce the salt expansion effectively and reduce the sensitive temperature range of salt expansion. In the case of using inorganic modifiers to improve the salt expansion deformation of the sulfate saline soil, considering the local climatic conditions, the amount of modifiers can be appropriately reduced in the areas with higher temperature, and when the temperature is lower, the amount of modifiers should be appropriately increased. Compared to that of the lime-improved soil,the compaction stage of the volcanic ash-improved soil is shortened, the elastic stage is increased, the generated strain when the soil sample reaches the strength limit is reduced, the soil structure is stronger, and the deformation resistance is enhanced. The addition of volcanic ash can also accelerate the strength growth rate of such saline soils. The deformation rate of salt expansion and collapsibility are both less than 1% by adding lime higher than 11% or lime +volcanic ash not less than 15%, and the 7-day saturated unconfined compressive strength of the improved soil is not less than 0.35 MPa.
引文
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[11]TB10621-2014高速铁路设计规范[S].2014.(TB10621-2014 Code for design of high speed railway[S].2014.(in Chinese))
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[13]申贝.地聚物胶凝材料固化硫酸盐渍土试验研究[D].兰州:兰州大学,2016.(SHEN Bei.Research on sulphate salty soil reinforced by geopolymer[D].Lanzhou:Lanzhou University,2016.(in Chinese))
[2]李宏波,沈晖,沈杰.粉煤灰固化超盐渍土的抗剪强度及耐久性[J].兰州理工大学学报,2015,41(3):140-144.(LI Hong-bo,SHEN Hui,SHEN Jie.Shearing strength and durability of hypersaline soil solidified with fly ash[J].Journal of Lanzhou University of Technology,2015,41(3):140-144.(in Chinese))
[3]田汉儒,亓振中,秦明亮,等.粗颗粒盐渍土化学改良试验研究[J].勘察科学技术,2016(6):5-7,27.(TIAN Han-ru,QI Zhen-zhong,QING Ming-liang,et al.Experimental study on chemical improvement of coarse grained saline soil[J].Site Investigation Science and Technology,2016(6):5-7,27.(in Chinese))
[4]文桃,米海珍,马连生,等.石灰改良黄土状硫酸盐渍土强度的影响因素研究[J].建筑科学与工程学报,2015,32(2):104-110.(WEN Tao,MI Hai-zhen,MA Lian-sheng,et al.Research on effect factors of strength of lime-treated loessial sulfate salty soil[J].Journal of Architecture and Civil Engineering,2015,32(2):104-110.(in Chinese))
[5]HOSSAIN K M A,MOL L.Some engineering properties of stabilized clayey soils incorporating natural pozzolans and industrial wastes[J].Construction and Building Material,2011,25(8):3495-3501.
[6]ABBASI N,MAHDIEH M,DAVOUDI M H.Application of lime and pozzolan for stabilization of silty sand soils in irrigation and drainage networks[J].Journal of Science and Technology of Agriculture and Natural Resources,2013,16(62):245-257.
[7]TB 10001-2016铁路路基设计规范[S].2016.(TB 10001-2016 Code for design of railway earth structure[S].2016.(in Chinese))
[8]TB 10102-2004铁路工程土工试验规程[S].2004.(TB10102-2004 Test regulations for geotechnical engineering of Railway Engineering[S].2004.(in Chinese))
[9]GB/T 50942-2014盐渍土地区建筑技术规范[S].2014.(GB/T 50942-2014 Technical code for building in saline soil regions[S].2014.(in Chinese))
[10]张莎莎,王永威,包卫星,等.影响粗粒硫酸盐渍土盐胀特性的敏感因素研究[J].岩土工程学报,2017,39(5):946-952.(ZHANG Sha-sha,WANG Yong-wei,BAO Wei-xing,et al.Research on the sensitive parameters of embankment deformation behavior for coarse-grained sulfate saline soil[J].Chinese Journal of Geotechnical Engineering,2017,39(5):946-952.(in Chinese))
[11]TB10621-2014高速铁路设计规范[S].2014.(TB10621-2014 Code for design of high speed railway[S].2014.(in Chinese))
[12]张莎莎,杨晓华,张秋美.天然粗粒盐渍土大型路堤模型试验研究[J].岩土工程学报,2012,34(5):842-847.(ZHANG Sha-sha,YANG Xiao-hua,ZHANG Qiu-mei.Research on large-scale embankment model test of crude coarse grained saline soil[J].Chinese Journal of Geotechnical Engineering,2012,34(5):842-847.(in Chinese))
[13]申贝.地聚物胶凝材料固化硫酸盐渍土试验研究[D].兰州:兰州大学,2016.(SHEN Bei.Research on sulphate salty soil reinforced by geopolymer[D].Lanzhou:Lanzhou University,2016.(in Chinese))