交联生物聚合物增强粉土抗压及抗剪强度的机理

杨海涛; 谢建斌; 江珊汕; 张浩南; 李志源; 叶宗昂

doi:10.11988/ckyyb.20231116

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长江科学院院报 ›› 2024, Vol. 41 ›› Issue (12) : 147-154. DOI: 10.11988/ckyyb.20231116

岩土工程

交联生物聚合物增强粉土抗压及抗剪强度的机理

杨海涛 ¹ ,
谢建斌 ¹^,² ,
江珊汕 ¹ ,
张浩南 ¹ ,
李志源 ¹ ,
叶宗昂 ¹

作者信息 +

Mechanism of Crosslinked Biopolymers Reinforcing Compressive and Shear Strength of Silty Soil

Author information +

文章历史 +

摘要

水泥作为当前较常用的土体加固材料,使用过程中会增加土壤pH值并存在一定污染地下水的风险。采用γ-聚谷氨酸(γ-PGA)、β-葡聚糖、γ-聚谷氨酸交联β-葡聚糖混合物(γ-PGA-β-G交联物)3种环保型材料加固粉土。通过粉土加固前后无侧限抗压强度试验、直剪试验、傅里叶红外光谱表征、扫描电镜微观观测试验,研究交联生物聚合物增强粉土抗压及抗剪强度机理。试验结果表明:交联生物聚合物增强粉土抗压及抗剪强度优于单一生物聚合物。交联生物聚合物掺量、养护龄期对粉土改良效果有显著影响。养护时间越长,改良粉土效果越好。在一定掺量范围内,改良粉土强度与掺量呈正相关。1.5%为γ-PGA-β-G改良粉土无侧限抗压强度最佳掺量,养护28 d无侧限抗压强度为47.07 kPa,较素粉土增长了1.43倍。γ-PGA-β-G交联物能有效提高粉土黏聚力及内摩擦角。其机制为γ-PGA-β-G交联物形成的三维网状结构具有较好力学性能,包裹粉土颗粒,进而显著提高粉土强度。

Abstract

Cement, currently a widely utilized soil reinforcement material, elevates soil pH and poses potential risks of groundwater contamination during application. This study employed three environmentally friendly materials, namely, γ-polyglutamic acid (γ-PGA), β-glucan, and a cross-linked γ-PGA-β-glucan mixture (γ-PGA-β-G crosslinker), to reinforce silty soil. The mechanism by which cross-linked biopolymers enhance the compressive and shear strength of silty soil was examined through unconfined compressive strength tests, direct shear tests, Fourier transform infrared spectroscopy (FTIR) characterization, and scanning electron microscopy (SEM) observations before and after reinforcement. Results indicated that the compressive and shear strengths of the silty soil reinforced with cross-linked biopolymers outperformed those reinforced with single biopolymers. The dosage of the cross-linked biopolymer and the age of maintenance significantly influenced the improvement effect. Longer maintenance periods better enhanced silty soil. Within a certain dosage range, the strength of silty soil positively correlated with the dosage. Specifically, a 1.5% ratio provided optimal unconfined compressive strength for γ-PGA-β-G-improved silt, with the 28-day maintenance strength reaching 47.07 kPa, a 1.43-fold increase over untreated silt. The γ-PGA-β-G cross-linked biopolymers effectively augmented the cohesion and internal friction angle of silt. This enhancement mechanism is attributed to the three-dimensional mesh structure formed by the crosslinks, which exhibits superior mechanical properties and envelops the silt particles, thereby significantly boosting the silt’s strength.

导出引用

杨海涛, 谢建斌, 江珊汕, 等. 交联生物聚合物增强粉土抗压及抗剪强度的机理[J]. 长江科学院院报. 2024, 41(12): 147-154 https://doi.org/10.11988/ckyyb.20231116

YANG Hai-tao, XIE Jian-bin, JIANG Shan-shan, et al. Mechanism of Crosslinked Biopolymers Reinforcing Compressive and Shear Strength of Silty Soil[J]. Journal of Yangtze River Scientific Research Institute. 2024, 41(12): 147-154 https://doi.org/10.11988/ckyyb.20231116

中图分类号： TU443 (膨胀性土与地基)

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Base on the test results of a large of samples from 158 projects, genetic type and typical combination geological sections of shallow silt soils in Siyang Area, Jiangsu Province, were analyzed respectively in terms of the sedimentary characteristics. Components of particles and chemical mineral composition and basic mechanical properties of the shallow silt soils were analyzed with the statistical analysis of the test results, combined with the static test and load test results, the correlation equation and the main physical and mechanical properties were established. Using variable head permeability test and typical engineering pumping test, borrow pits compaction test and standard penetration test, Permeability, compaction and liquefaction were studied. Using laboratory head test and field pumping test results show that the permeability index difference of 1~2 orders of magnitude, the field pumping test index is closer to the actual penetration of shallow silt soils in the study area; the characteristics of shallow silt soils with bad water stability and not easy compaction; the liquefaction of the shallow silt soil occurred extensively in the study area, liquefaction grade from mild liquefaction to serious liquefaction, the regional characteristics of significant. The research results provide some good advice for the planning and construction of Siyang city, and also provide basic information for further research.

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