冷挺, 唐朝生, 徐丹, 李运生, 张岩, 王侃, 施斌. 2018: 膨胀土工程地质特性研究进展. 工程地质学报, 26(1): 112-128. DOI: 10.13544/j.cnki.jeg.2018.01.013
    引用本文: 冷挺, 唐朝生, 徐丹, 李运生, 张岩, 王侃, 施斌. 2018: 膨胀土工程地质特性研究进展. 工程地质学报, 26(1): 112-128. DOI: 10.13544/j.cnki.jeg.2018.01.013
    LENG Ting, TANG Chaosheng, XU Dan, LI Yunsheng, ZHANG Yan, WANG Kan, SHI Bin. 2018: ADVANCE ON THE ENGINEERING GEOLOGICAL CHARACTERISTICS OF EXPANSIVE SOIL. JOURNAL OF ENGINEERING GEOLOGY, 26(1): 112-128. DOI: 10.13544/j.cnki.jeg.2018.01.013
    Citation: LENG Ting, TANG Chaosheng, XU Dan, LI Yunsheng, ZHANG Yan, WANG Kan, SHI Bin. 2018: ADVANCE ON THE ENGINEERING GEOLOGICAL CHARACTERISTICS OF EXPANSIVE SOIL. JOURNAL OF ENGINEERING GEOLOGY, 26(1): 112-128. DOI: 10.13544/j.cnki.jeg.2018.01.013

    膨胀土工程地质特性研究进展

    ADVANCE ON THE ENGINEERING GEOLOGICAL CHARACTERISTICS OF EXPANSIVE SOIL

    • 摘要: 根据近年来国内外学者围绕膨胀土工程地质特性取得的研究成果,着重从胀缩性、裂隙性、超固结性、强度、渗透性、微观结构及工程处治技术等几个方面总结了该课题的研究现状及进展,得到如下认识:(1)胀缩性主要取决于强亲水性黏土矿物含量、水/力边界条件及初始状态,在干湿循环条件下具有不可逆性,关于胀缩机理学界存在不同的观点;(2)裂隙性是膨胀土区别于一般土体的显著特征之一,裂隙的存在会极大破坏土体的整体性,弱化力学性质,是许多工程地质问题的直接或间接原因,裂隙形成过程与膨胀土矿物成分、微观结构和干燥过程中的内应力发育状态有关;(3)超固结性使膨胀土具有较大结构强度和水平应力,易在开挖过程中引起较强的卸荷效应,是促进边坡失稳的重要因素;(4)膨胀土的强度随干湿循环次数增加而逐渐降低,并最终趋于稳定,其中裂隙发育和土结构调整在此过程中起关键作用;(5)渗透性在很大程度上受裂隙的控制,但目前关于两者之间的定量关系还缺少系统研究;(6)微观结构反应了膨胀土的形成条件和应力历史,是决定其宏观物理力学性质的主要因素,开展微观结构研究是掌握膨胀土宏观性质本质规律的重要途径。在工程处治技术上,本文重点介绍了近些年发展起来的膨胀土路堤物理处治技术和路堑边坡柔性支护技术。最后,针对该课题的研究现状,笔者提出了今后的研究重点和方向,主要包括胀缩性和力学性质的各向异性、裂隙形成的力学机理、裂隙形态特征与工程地质特性之间的定量关系、宏-微观力学模型耦合问题及多场耦合作用下膨胀土工程性质响应特征等。

       

      Abstract: Expansive soil is considered as a problematic soil in engineering, because it usually results in various engineering geological problems and disasters. According to the published results on the engineering geological characteristics of expansive soil in recent years, the advances on swelling-shrinkage behavior, desiccation cracking, overconsolidation, strength, permeability and microstructure of expansive soil were summarized, and the following main knowledge was obtained. (1)The swelling-shrinking characteristics are mainly related to the fraction of expansive clay minerals, hydro-mechanical boundary conditions and initial state. Irreversible volumetric deformation would occur when the expansive soil is subjected to wetting-drying cycles. Until now, there is still not a uniform viewpoint on the intrinsic mechanism on swelling-shrinking behavior. (2)Desiccation cracking is one of the salient features to distinguish expansive soil from other soils. The presence of cracks in soil can significantly undermine the overall structure of the soil, greatly weaken the mechanical properties and lead to many engineering geological problems directly or indirectly. The formation of desiccation cracks is related to expansive soil mineral composition, microstructure and the development of internal stress during drying. (3)Overconsolidation makes expansive soil has a greater structural strength and horizontal stress. Stress-release cracks are easy to occur when the expansive soil slope is excavated, which can damage the overall structure of the soil and promote landslide.(4)In terms of strength, most of studies focused on the effect of wetting-drying cycles. Generally, the strength decreases gradually with increasing wetting-drying cycles and eventually reaches stabilization. The wetting-drying cycle induced presence of cracks and microstructure arrangement are the two factors responsible for the corresponding strength changes. (5)The hydraulic conductivity is largely controlled by cracks. It is therefore important to consider the crack effect when performing permeability test in laboratory.(6)Microstructure of the expansive soil reflects the formation conditions and stress history. It is a fundamental factor controlling the macro-physical and mechanical behavior. Microstructure analysis is also the important way and theoretical basis to explore the intrinsic mechanisms of the observed macroscopic properties. Furthermore, as for as expansive soil engineering treatment technology, this article focused on the physical treatment technology for embankment filled with expansive soil and flexible supporting technology for expansive soil cut slope. Based on the above understanding and current research shortages in this field, some important research topics that should be well investigated in future were proposed, including anisotropic behavior of swelling-shrinking, mechanism of the desiccation cracking, quantitative relationship between geometrical parameters of cracks and the indicators of macro engineering properties, the coupling of macro-micro mechanical model and the hydro-mechanical response characteristics of expansive soil under multi-field coupling condition, et al.

       

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