摘要
在西北季节冻土区广泛分布着黄土状硫酸盐渍土,受气候环境变化影响,其盐冻胀特性极其显著,往往诱发多种工程病害,亟待寻找经济合理、技术可靠的固化方法。针对水泥、石灰等传统固化剂改良硫酸盐渍土盐冻胀特性失效的现状,大量前期预试验发现沸石、聚丙烯纤维和木质素磺酸钙三种材料改良黄土状硫酸盐渍土的盐冻胀性效果显著,但对土体强度的影响各有利弊。鉴于此,本研究同时兼顾盐渍土强度和盐胀改良效果,提出将这3种改良剂复合使用,并基于响应曲面法得到3种改良剂的最优配比。按改良剂最优配比分别配制不同试验条件下的复合改良黄土状硫酸盐渍土,研究含盐量、含水量、干密度、改良剂掺量、养护龄期和冻融次数对改良前后盐渍土无侧限抗压强度的影响。试验结果表明:盐渍土及改良土的无侧限抗压强度,随含盐量、含水量及冻融次数的增加均逐渐减小,随干密度、改良剂掺量及养护龄期的增加而增大,养护龄期对盐渍土的抗压强度影响较小。复合改良剂可以显著提升盐渍土的抗压强度,且减弱了含盐量及冻融循环对抗压强度的降低作用,并增强了干密度和养护龄期对抗压强度的提升作用,但随着含水量的增加改良效果有所减弱。另外,复合改良剂对盐渍土在冻融循环作用下的累积盐冻胀变形、残余盐胀变形均有显著的抑制作用。
Sulfate saline soil has the characteristics of salt heave,dissolution-induced subsidence,corrosion,and poor water stability,which cause its physical and mechanical properties to be complex and unstable.Loesslike sulfate saline soil is widely distributed in the seasonally frozen soil regions of northwest China.It exhibits the common unfavorable engineering characteristics of loess and sulfate saline soil and complex occurrence(ir⁃regular spatial distribution,poor continuity,surface agglomeration,etc.).Additionally,it is highly concealed and difficult to control,often leading to engineering issues such as bulging,subsidence,and cracking in various structures.Moreover,due to the influence of the unique climate and environmental changes in northwest China,the salt-frost heave characteristics of loess-like sulfate saline soil are particularly pronounced,often causing engi⁃neering problems.Therefore,it is urgent to find an economical,practical,and technically reliable stabilization method.In response to the ineffectiveness of traditional curing agents such as cement and lime in improving the salt-frost heave properties of sulfate saline soil,numerous preliminary tests have found that three materials—zeo⁃lite,polypropylene fiber,and calcium lignosulfonate—significantly improved the salt-frost heave properties of loess-like sulfate saline soil,though their influence on soil strength varied,each with its own advantages and dis⁃advantages.Accordingly,this study considered both the strength of saline soil and the improvement in salt heave,proposing the composite use of these three amendments.Based on the response surface method,the opti⁃mal mix ratio of these amendments was determined.The composite-improved loess-like sulfate saline soil was prepared under different test conditions using the optimal mix ratio of amendments.The influence of salt con⁃tent,water content,dry density,amendment dosage,curing age,and number of freeze-thaw cycles on the un⁃confined compressive strength of saline soil before and after improvement was investigated.The experimental re⁃sults showed that the unconfined compressive strength of saline soil and improved soil decreased with increasing salt content,water content,and number of freeze-thaw cycles,but increased with higher dry density,amend⁃ment dosage,and curing age.Overall,curing age had a minor influence on the compressive strength of saline soil.The composite amendment significantly improved the compressive strength of saline soil,reduced the weakening effects of salt content and freeze-thaw cycles,and enhanced the strengthening effects of dry density and curing age.However,the improvement effectiveness weakened with increasing water content.Further⁃more,the composite amendment significantly inhibited the accumulated salt-frost heave deformation and residu⁃al salt heave deformation of saline soil under freeze-thaw cycles.
作者
丁玉涛
王莉杰
赵栋
韩善博
周凤玺
丑亚玲
DING Yutao;WANG Lijie;ZHAO Dong;HAN Shanbo;ZHOU Fengxi;CHOU Yaling(China Energy Engineering Group Gansu Electric Power Design Institute Co.,Ltd.,Lanzhou 730050,China;Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province,Lanzhou University of Technology,Lanzhou 730050,China;Northwest Center for Disaster Mitigation in Civil Engineering of Ministry of Education,Lanzhou University of Technology,Lanzhou 730050,China)
出处
《冰川冻土》
2025年第4期1033-1049,共17页
Journal of Glaciology and Geocryology
基金
国家自然科学基金项目(52168052)
甘肃省教育厅产业支撑计划项目(2025CYZC-033)
中国能源建设集团甘肃省电力设计院有限公司科学技术项目(2020-kc-ky-02)
青海省重点研发与转化计划项目(2025-QY-217)资助。
关键词
复合改良
黄土状硫酸盐渍土
最优配合比
强度特性
盐冻胀
composite improvement
loess-like sulfate saline soil
optimal mix ratio
strength characteristics
salt-frost heave
