Orientation of Deposition Planes and Shear Strength of Typical Clays from Pakistan

Nawaz, Mohsin; Israr, Jehanzaib

doi:10.1007/s40996-019-00267-x

Cited by 7 publications

(2 citation statements)

References 23 publications

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“…Failure of civil engineering structures such as buildings, roads, railway tracks, runways, walkways, embankments, and canal linings have been reported owing to volumetric expansion and shrinkage upon drying and wetting, respectively, for fat clays [1][2][3][4].Consequently, billions of dollars are lost throughout the world annually e.g., only in the United States an economic loss of about 9 billion USD per annum has been reported [5].Similar damages to structures constructed on fat clays have also been reported in Pakistan; for instance, significant infrastructural loss at Shah Abdul Latif University, Khairpur and Gomal University, Dera Ismail Khan was documented by Farooq [6]. Fat clays are present at various locations of Pakistan including but not limited to Dera Ghazi khan, Dera Ismail Khan, Sialkot, Narowal and Gujranwala [7,8]. The use of such fat clays without stabilization as embankment material leads to failure [9].…”

Section: Introductionmentioning

confidence: 84%

Amelioration of fat clay treated with cohesive and cohesion less soils

Farooq,

Mujtaba,

Ashiq

et al. 2024

Preprint

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The present study is aimed to evaluate the amelioration of fat clay by blending it with cohesive non-swelling soil (CNS) and cohesionless silty sandy soil (termed as Kassu). Fat clay sample with liquid limit (LL) 50, plasticity index (PI) 26 was collected from a site located near Narowal city while CNS and Kassu samples were procured from sites located at outskirts of Lahore (Pakistan). Geotechnical parameters evaluated after conducting tests on virgin soil indicated it as unsuitable soil for construction purposes. A series of laboratory tests were performed after blending fat clay with CNS and Kassu in different proportions ranging between 0 ~ 35% with 5%intervals. The laboratory tests including modified Proctor compaction, unconfined compression, California bearing ratio (CBR)and one-dimensional consolidation tests in addition to classification tests were performed on virgin and blended samples. The LL decreased from 50–32% and PI reduced from 24 to 13 with 35% addition of CNS while for Kassu LL and PI reduced to 29% and 12, respectively. CBR value of blended samples increased from 4–7% making the blended soil an acceptable subgrade for roads and foundation construction. Also, swell potential reduced from 4–1.2% ~ 0.26% for blended samples. Regression models have been proposed to predict swell pressure and ultimate swell potential of CNS and Kassu-treated swelling clays. Based on the study, it was concluded that significant improvement in mitigating expansive characteristics of fat clay can be achieved by blending it with CNS and Kassu. Meanwhile, CNS is observed to be more effective as compared to Kassu in controlling the swell properties of the fat clay.

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Section: Introductionmentioning

confidence: 84%

Amelioration of fat clay treated with cohesive and cohesion less soils

Farooq,

Mujtaba,

Ashiq

et al. 2024

Preprint

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“…According to this definition, for a soil sample under an isotropic stress state, that is η 0 = 0 (k 0 = 1), the yield surface is initially symmetrical with respect to the hydrostatic axis in the p−q plane, implying that the soil may possess inherent isotropic fabric, which is false. Although σ h /σ v = 1 (η 0 = 0), the initial inherent fabric of soils associated with their specific microstructures would have been formed during particle sedimentation or sample preparation process, as manifested by different initial stiffnesses in the vertical and horizontal directions [23][24][25] and dramatically different mechanical responses owing to different bedding plane orientations [26][27] or loading directions. 28 However, the conventional RH framework in which the rotational angle is the only anisotropy measure of soils cannot capture the significant interplay 29 between the material's fabric anisotropy and loading direction.…”

Section: Introductionmentioning

confidence: 99%

Bounding surface rotational hardening model for overconsolidated clay accounting for evolving fabric anisotropy

Yang

2022

Num Anal Meth Geomechanics

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Soil is inherently anisotropic owing to the sedimentation process under gravity and is generally under anisotropic stress state in the field. To reflect the influence of anisotropic consolidation, rotational hardening (RH) is favorably used in constitutive models, mimicking in-situ stress conditions. However, most of the existing models do not account for the inherent anisotropy of clays under isotropic stress state as well as the interplay between the fabric and loading direction, and the corresponding initial yield surface is assumed to be oriented along the hydrostatic axis. Furthermore, as the rotational angle is usually deemed as the clayed soil's anisotropy measure, a critical yield surface without rotation appears to contradict the highly anisotropic fabric at critical state. In this study, an anisotropic bounding surface model that incorporates RH and fabric anisotropy is formulated to simulate the behavior of overconsolidated (OC) clay subject to different consolidation histories, while addressing the aforementioned inconsistency issue. During the loading process, both fabric anisotropy and rotational angle evolve continuously based on their respective evolution rules. Fabric anisotropy evolves to the critical state when the rotational angle returns to zero, satisfying the anisotropic critical state theory (ACST). In addition, the model employs an anisotropic elasticity to consider the influence of the initial fabric at a low-stress level. The predictive capacity of the model can be demonstrated by simulating several compression and extension tests on clay over a wide range of overconsolidation ratios (OCRs) and anisotropic consolidation stress ratios under both drained and undrained conditions.

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