The properties of soils are highly complex, and therefore, the classification system should be based on multiple perspectives of soil properties to ensure effective classification in geotechnical engineering. The current study of research demonstrates a lack of correlation between classification systems based on soil plasticity and those based on in-situ mechanical properties of soils. A CPTu-based plasticity classification system is proposed using the soil behaviour type index (Ic), with its reliability and limitations discussed. The results indicate that (1) Ic has the capacity to predict the stratigraphic distribution from the in-situ mechanical properties of soils. It showed a significant linear correlation with wL, which soil classification zone was similar to that of clay factor (CF); (2) A CPTu-plasticity classification system is proposed to characterize both plasticity and in-situ mechanical properties of soils. This system allows for the initial classification of soils solely based on CPTu data. Furthermore, it has been established that Ic = 2.95 can delineate the boundary between high- and low-compressibility soils. (3) The error is only 25.2% relative to the Moreno-Maroto classification chart, and the system tends to classify soils of intermediate nature as clay or silt. The distance between the data points and both the C-line and the new C-line (Delta Ip, Delta IpIc) showed a significant positive correlation. Only one data point was misclassified, considering human error in measuring Ip. (4) The new classification chart has been found to be more applicable to offshore and marine soils.

Land reclamation from the sea is increasingly common in coastal areas in China as its urban population continues to grow and the construction of subways in these areas becomes an effective way to alleviate transportation problems. Earth pressure balance shield (EPBS) tunneling in reclaimed lands often faces the problem of seawater erosion which can significantly affect the effectiveness of soil conditioning. To investigate the impacts, in this work, the stratum adaptability of EPBS foaming agents in seawater environments was evaluated based on a series of laboratory tests. The Atterberg limits and vane shear tests were carried out to understand the evolution characteristics of mechanical properties of clay-rich soils soaked in seawater and then conditioned with foams. The results revealed that, for the same foaming agents, the liquid limit and plastic limit of soils soaked in seawater were lower than those in deionized water due to the thinning of bound water films adsorbed on the surface of soil particles. Similarly, soils soaked in seawater had lower shear strength. In addition, the results indicated that the foam volume (FV) produced by foaming agents using seawater as the solvent was slightly higher than that when using the deionized water due to the higher hydration capacity of inorganic salt cations in seawater compared with organic substances. It was also shown that seawater had negative effects on the half-life time (T1/2) and the dynamic viscosity (eta) of foaming agents due to the neutralization reaction between anions in the foaming agents and Na+ present in seawater. The test results also confirmed that 0.5 % of the tackifier (CMC) can alleviate the issue of thin foam films caused by seawater intrusion and improve the dynamic viscosity of foaming agents more effectively, leading to superior resistance to seawater intrusion in EPBS tunnel constructions.

Seismically induced soil liquefaction was listed as one of the major causes of damage observed in the natural and built environment during the 2023 Turkiye-Kahramanmaras earthquake sequence. Reconnaissance field investigations were performed to collect perishable data and document the extent of damage immediately after the events. The sites with surface manifestations of seismic soil liquefaction in the form of soil ejecta, excessive foundation and ground deformations were identified and documented. The deformations were mapped, and samples from ejecta were retrieved. The ejecta samples were predominantly classified as sands with varying degrees of fines. Laboratory test results performed on liquefied soil ejecta revealed that the fines-containing liquefied ejecta samples are mostly classified as low plasticity clays (CL). Most of CL soil type ejecta were retrieved from Golbasi-Adiyaman region. The liquid limits of these samples varied in between 32 and 38%, their plasticity index values were estimated in the range of 16-23%. Surprisingly, two ejecta samples with plasticity indices higher than 30% were retrieved from Hatay airport, one of which was classified as high plasticity clay (CH). The majority of the fine-grained ejecta samples fall either on Zone B: Testing Recommended region of the Seed et al. (Keynote presentation, 26th Annual ASCE Los Angeles Geotechnical Spring Seminar, Long Beach, CA, 2003) susceptibility chart. Moreover, 12 out of 74 samples fall outside the susceptible limits defined by Seed et. These preliminary results suggest that clayey soils can produce liquefied ejecta when subjected to cyclic loading. Detailed site investigation and laboratory testing programs are ongoing to further investigate this rather unexpected response. Until their findings become available, the liquefaction susceptibility of silty-clayey soils' mixtures is recommended to be assessed conservatively with caution.

The 6 February 2023 Kahramanmara & scedil;-T & uuml;rkiye earthquake sequence (M7.8 and M7.6) presents an exceptional opportunity to investigate both the effects of local soil conditions on damage patterns under strong shaking conditions and the performance of building foundations in areas that experienced ground failure. The significant ground failure and structural damage in Ad & imath;yaman-G & ouml;lba & scedil;& imath; triggered an intensive series of detailed reconnaissance and field surveys. This article aims to present the resulting database of observations on ground failures, building, and foundation performances. The field reconnaissance of ground failures and their effects on building performances involved aerial and walk-down surveys, including high-quality photographs taken across the town. In addition, data on building damage statistics compiled by the Ministry of Environment, Urbanization, and Climate Change were accessed and analyzed. The subsurface characteristics of the town were characterized using available data from pre-earthquake site investigation campaigns employed for town planning purposes. It is concluded that the ground failures in the town primarily resulted from soil liquefaction and cyclic softening. Most of the poor building and foundation performances and ground failures were documented in the northern part of Atat & uuml;rk Boulevard, closer to the lake of G & ouml;lba & scedil;& imath;, where soil site characteristics were unfavorable. This revealed once again the significant effects of local soil site conditions, particularly soil liquefaction, on the intensified ground failures, foundation, and structural damage levels.

This study examines the effectiveness of the bi-stabilization of clay soils using cane molasses and coconut fiber, focusing on improving the geotechnical and mechanical properties of clay. The performance of the two stabilizers, both individually and in combination for bistabilization, was assessed. The geotechnical properties were determined through sieve analysis, Proctor tests, and Atterberg limit methods, while the mechanical properties were measured using a hydraulic press. The results showed that cane molasses reduced plasticity, enhanced soil cohesion, and increased dry density with molasses content. The Atterberg limits (liquid limit, plastic limit, and consistency index) were maximized at a 4% molasses content, with respective increases of 9.28%, 44.80%, and 37.9% compared to clay without molasses (CB). Coconut fiber improved the flexural strength by 361.9% for CF1, whereas molasses improved the compressive strength by 12.24% compared to plain clay. Bi-stabilization allowed for a maximum improvement in flexural strength of 509.52% compared to CB, 49.42% compared to molasses-stabilized clay bricks (CSM), and 31.96% compared to clay composites with coconut fiber (CF). The compressive strength improved by 22.54% compared with CB, 9.21% compared with CSM8, and 14.94% compared with CF 1/2. In summary, bi-stabilization with sugarcane molasses and coconut fiber provided enhanced performance compared with their individual use.

Highway, road, and airfield construction on weak soils is costly endeavor. Re-use of agricultural waste is widely employed as a stabilizing agent to improve engineering properties of these soils. In this study, rice husk ash (RHA), a by-product of incineration of husk from rice production, was used as a potential stabilizer. The water absorption and retention rate of the stabilizer, denoted as W-ab, is determined by measuring the amount of water that is absorbed and retained by the stabilizer in relation to its initial dry mass. The study involved treatingAo clay, imitating a dredged soil with highwater content, at various addition ratios (ARHA). Diverse curing periods were applied to assess the liquid limits (w(L)), plastic limits (w(P)), and cone index (q(c)) of the treated clays. Compaction characteristics were also determined for several ARHA and different curing periods. The test results show an increase in both w(L) and w(P) with decrease in plastic index (I-p) with increase in ARHA, but no remarkable change in w(L) and w(P) associated with curing. Compaction characteristics show a decline in rho(dmax) and increase in wopt with increase in ARHA, but no notable changes in rho(dmax) and wopt with cured samples. Increase in q(c) with ARHA, but no noteworthy change in q(c) with curing was discerned through cone index test. The trends for curing observed in the above test results were consistent with that observed for W-ab. The results were then modified based on the W-ab of stabilizer. The measured water content (w) and liquidity index (IL) were modified to account for absorbed water (w*), which gave a better correlation with q(c) than w. The compaction characteristics were also modified based on Wab, ARHA and the results suggest that treated clays were able to achieve modified dry density (rho(dmax)*) at the same values of modified water content (w(opt)*).

In this paper, the effect of salt (Na2SO4, NaCl) on the clay Atterberg limits and shear strength is revealed by using volumetric flask test and triaxial shear test, and the macroscopic mechanical performance results of the Atterberg limits and triaxial shear test reveal the mechanism of salt solution's effect on the evolution of the deterioration of the microscopic pore structure of the soil body based on the perspective of microscopic pore characterization by using nuclear magnetic resonance (NMR) scanning and scanning electron microscopy (SEM) techniques. The results show that in Na2SO4 solution and NaCl solution, the decrease of double layer thickness and the increase of PH value caused by the increase of cation concentration are the main reasons for the gradual decrease of soil Atterberg limits, adsorbed bound water (ABW) content and shear strength. In addition, when the cation concentration is the same, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text{SO}_{4}{2-}$$\end{document} has a greater barrier effect like semi-permeable film than Cl-, which makes the double layer thickness of Na2SO4 solution thinner than NaCl solution, the Atterberg limits and ABW content is further reduced; Meanwhile, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text{SO}_{4}{2-}$$\end{document} has greater intergranular repulsion on the particle surface compared to Cl-, forming a larger pore structure further deteriorating the soil structure and reducing the soil shear strength. It provides more support for studying the effect of salt on the physical and mechanical properties of clay.

Freeze-thaw cycle is an environmental process characterized by the repeated and consecutive freezing and thawing of soil. This cycle can induce significant changes in soil properties, which have profound implications for infrastructure stability, agricultural productivity, and environmental conservation. This review paper explores the impact of freeze-thaw cycles on the engineering and index properties of soil, including permeability, porosity, density, Atterberg limits and consistency, compressibility, compaction properties and shear strength. Freeze-thaw process is a critical environmental factor that affects soil behaviour, particularly in regions with seasonal temperature fluctuations. Hence, a complete understanding of these effects is essential for applications in civil engineering, agriculture, and environmental management.

Background The structure of flexible or rigid pavement built on expansive subgrade soil that has a volumetric change is vulnerable to many problems that might cause failure. Pavement and construction became more durable and economical by enhancing the quality of subgrade expansive soil. Solid waste recycling has become very popular recently as a means of attaining sustainable waste management, so using lime kiln dust (LKD), which is a by-product of quick lime production, to treat expansive soil in pavement subgrades. This research describes the effect of LKD on the chemical composition, strength, and swelling of high and low-plastic clay that were extracted from two sites. The minimum LKD required for treating expansive soils was determined by using the Eades and Grim pH test. From tests, it was found that the addition of LKD increased the shrinkage limit by a range (250-500)% and decreased the plasticity and swelling potential by between (50 and 100)% of expansive subgrade soils. The strength according to CBR, increased approximately by 150% for CL soil and 800% for CH soil.Results The optimal percentage of LKD for CH soil is 6%, and for CL soil, it is 2%. The plastic limit increased by 50% for CH soil at 6% LKD. On the other hand, CL soil became non-plastic at 4% LKD. With an increase in the percentage of LKD, it led an the increase in the shrinkage limit by 500% in CH soil and 250% in CL soil. The free swell decreased by 50% in CH soil and 100% in CL soil. The swelling pressure decreased by 50% for two expansive soils. CBR increased by 800% in CH soil and by 150% in CL soil.Conclusion This work found that the addition of LKD improves the physical, chemical, and mechanical properties of expansive subgrade soil.

Suction stress, the part of effective stress induced by soil-water interaction, is the source for the intrinsic cohesion of fine-grained soil slurries. Here, the previous unified effective stress equation is generalized to extend the suction stress variation from the liquid state to the oven-dry state, yielding an augmented closed-form equation. This equation includes a new term, named slurry adsorptive suction stress, to incorporate the adsorptive mechanism of soil slurries at the liquid state. This adsorption mechanism involves the interparticle van der Waals attraction, face-to-edge attraction, and electrical double-layer repulsion when soils are in the liquid state. The proposed equation is validated with a wide array of 12 fine-grained soils' shrinkage curves, modulus, and suction stress data measured by the drying cake test. It is demonstrated that the proposed equation can excellently capture the experimental data across all saturations. Furthermore, the practical implications of the proposed model are illustrated via its relevance to rheological properties of soil slurries and correlations with both liquid limit and plastic limit. (c) 2024 American Society of Civil Engineers.