Civil Engineering / İnşaat Mühendisliği

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  • Article
    Citation - WoS: 16
    Citation - Scopus: 19
    Comparative Analysis of Estimation of Slope-Length Gradient (ls) Factor for Entire Afghanistan
    (Taylor & Francis, 2023) Ansari, Ahmad; Tayfur, Gökmen
    Slope length gradient (LS) is one of the crucial factors in the Universal Soil Loss Equations (USLE, RUSLE). This study aimed at estimating the slope-length and slope-steepness (LS) factor for the entire watersheds of Afghanistan by using three different methods, namely; (1) LS-TOOLMFD (Method 1); (2) The Method of Equations (Method 2); and (3) The approach of Moore and Burch (Method 3). The first method uses the digital elevation model (DEM) in the ASCII format, and the other two methods use the DEM in the spatial domain. The results show that the LS-factor of the study area ranges from 0.01 to 44.31, with a mean of 5.24 and standard deviation of 6.95, according to Method 1; 0.03 to 163.49, with a mean of 9.6 and standard deviation of 13.58, according to Method 2; and 0 to 3985, with a mean of 7.16 and standard deviation of 29.7, according to Method 3. The study reveals that Methods 1 and 2 are more appropriate than Method 3 because Method 3 yields high LS-factor values close to or at streamlines located near mountainous regions. The highest LS values are found to be in the northeast, north, and central regions of Afghanistan, which is consistent with the high mountains and deep valley geomorphology, indicating that these regions are particularly vulnerable to soil erosion by rainfall-runoff processes. The sediment delivery ratio (SDR) for the Upper-Helmand River Basin (Upper-HRB) is also estimated by the RUSLE, employing the LS factors produced by the three methods. The results revealed that the average annual soil loss is found to be, respectively, 9.3, 18.2, and 11.1 (ton/ha/year) by using the three methods, corresponding to SDR of 23.5%, 12.1%, and 19.9%.
  • Article
    Citation - WoS: 13
    Citation - Scopus: 13
    Effect of Soil-Type and Fines Content on Liquefaction Resistance—shear-Wave Velocity Correlation
    (Taylor & Francis, 2020) Ecemiş, Nurhan
    Direct measurement of shear-wave velocity, Vs, in the field to evaluate the liquefaction resistance of soils is an alternative or complement approach to penetration-based methods. However, the existing liquefaction assessment methods established on the Vs have uncertainties about how the fines content and soil-type change the relationship between Vs and liquefaction resistance. The first part of this paper discusses the existence of fines on the correlation between cone penetration resistance and Vs. The second part focuses on the liquefaction resistance that is construed over again using the simplified cone penetration test (CPT)-based liquefaction screening procedure in terms of Vs for three distinct ranges of non-/low plastic fines content <35% fines. The outcomes of the investigation indicate that for each fines content, the correlation between CRR and Vs1 is not unique; there is a significant scattering of the curves for different soil types. Finally, using the results of this investigation as well as the simplified CPT-based liquefaction screening method, a soil-type specific CRR–Vs1 relationship developed for the unbounded, very young (Holocene-age) soils. © 2018 Taylor & Francis Group, LLC