Div ASCE Research Articles

A zero-thickness interface element incorporating hydro-chemo-mechanical coupling and rate-dependency

The interfaces play a key role in many engineering problems involving geologic materials. In particular, slope stability analyses of ancient landslides (that were subjected to large displacements along a slip surface) need the formulation of ad hoc interface elements. The mechanical response of slip surfaces in clays is affected by hydro-chemo-mechanical interactions and by rate effects and this paper presents the formulation of an innovative zero-thickness interface element for dealing with these kinds of effects. The proposed interface element is an extension of the modified zero-thickness element proposed by Goodman et al. (J Soil Mech Found Div ASCE 94:637–659, 1968). In addition to solid displacement, we consider the flow of water and the diffusion of a single salt in the fluid phase. Terzaghi’s effective stress principle is used leading to the usual hydro-mechanical coupling within the interface element. The fluxes of water and salt are considered in the longitudinal and in transversal directions of the interface element. For the constitutive relation, we propose an innovative nonlinear elastic energy that improves the numerical convergence in the occurrence of interface opening. The Mohr–Coulomb yield surface is used for the plastic regime in which we considered the effects of strain rate and salt concentration on the shearing behaviour of the interface element. The proposed element has been implemented in a user-defined subroutine of ABAQUS. The typical effects of salt concentration and displacement rate and the typical model responses for the longitudinal and transversal fluxes of salt and pore fluid are discussed in detail. Finally, the proposed interface element is validated through the comparison with experimental results.

An empirical strength criterion for the Antalya tufa rock, southern Turkey

This paper formulates an empirical strength criterion for the heterogeneous Antalya tufa rock mass assuming that the heterogeneity effect is represented by the unit weight and the porosity of the tufa rock, which is highly variable from a geomechanical point of view. Unconstrained non-linear regression analyses have been used to identify the strength criterion and material constants in terms of fitting an equation and determining its regression parameters. Prior to this approach, the fitting of the laboratory data to the failure criteria defined by Coulomb (Mem Acad R Des Sci 3:38, 1776), Bieniawski (J S Afr Inst Min Metal 74(8):312–320, 1974) and Hoek and Brown (J Geotech Eng Div ASCE 106(GT9):1013–1035, 1980) has been performed by means of constrained regression analyses. For the regression analyses, the results of the uniaxial and triaxial compressive strength tests along with the Brazilian tensile strength tests have been used. The regression analysis has been performed in two stages. In the first stage, the results of the uniaxial and triaxial compressive strength tests have been included in the analyses; in the second stage, the results of the Brazilian tensile strength tests have been added to the regression analyses performed in the first stage.

Effect of instream sand mining on hydraulic variables of bedload transport and channel planform: an alluvial stream in South Bengal basin, India

Sand mining adversely behaves with changing river system, especially in the bedload transport process. This study aims to find out the relationships between river water flows, sediment transport regime in bedload transport and also tries to determine how instream mining affect the sediment inflow and channel planform change. The field study has been conducted in three selected sites on Kangsabati River situated in the lower, middle and upper course. Several established equations were applied to derive the results from water flow and sediment regime. GSTAT was used to prepare coarse medium (CM) diagrams and tractive current deposits to analyze the trend of sediment throughout the river course. Sediment and bedload transport were measured using Ackers and White (J Hydraul Eng Div ASCE 99(hy11):2041–2060, 1973) and Meyer-Peter–Muller methods (IAHSR 2nd meeting, Stockholm, appendix 2. IAHR, 1948). Shear stress and critical shear stress were computed using Shields (Application of similarity principles and turbulence research to bedload movement, 1936) and DuBoys equations whereas Friend and Sinha’s method (Braiding and meandering parameters, vol 75, No 1, Geological Society, London, 1993) was used to detect irregular planform response caused by sand mining. Regression analysis denotes that mining intensity can be change the shear stress (R2 = 0.972); velocity (R2 = 0.683); grain diameter (R2 = 0.555) and sediment concentration (R2 = 0.997) on bedload transport. Mining activities can be changes of hydraulic responses as well as interruption of sediment and bedload transport throughout the channel. In context of sand mining, planform response denotes that thalweg shifting leads to massive sandchar deposition in upper course, huge channel incision causes river bank erosion in middle course and pool–riffle alteration expanded in channel and pit area in lower course.

Reliable method of determining stable threshold channel shape using experimental and gene expression programming techniques

The geometric dimensions and bank profile shape of channels with boundaries containing particles on the verge of motion (threshold channels) are significant factors in channel design. In this study, extensive experimental work was done at different flow velocities to propose a reliable method capable of estimating stable channel bank profile. The proposed method is based on gene expression programming (GEP). Laboratorial datasets obtained from Mikhailova et al. (Hydro Tech Constr 14:714–722, 1980), Ikeda (J Hydraul Div ASCE 107:389–406 1981), Diplas (J Hydraul Eng ASCE 116:707–728, 1990) and Hassanzadeh et al. (J Civil Environ Eng 43(4):59–68, 2014) were used to train, test, validate and examine the GEP model in various geometric and hydraulic conditions. The obtained results demonstrate that the proposed model can estimate bank profile characteristics with great accuracy (determination coefficient of 0.973 and mean absolute relative error of 0.147). Moreover, for practical calculations of channel dimensions, the model provides a specific mathematical relationship to solve problems with different discharge rates (Q) and particles with various median grain sizes (D50). The proposed model’s performance is compared with 8 relationships suggested previously by researchers (based on empirical and theoretical analyses) and a relationship obtained using a nonlinear regression model with different experimental data. The polynomial VDM and two exponential functions, i.e. IKM and DIM, are introduced as the superior existing models. According to the present study results, the proposed GEP model can predict the bank profile shape trend well and similar to the experimental datasets. Sensitivity analysis was also applied to assess the impact of each input variable (x, Q and D50) on the presented relationship. According to the current study, the GEP model provides a suitable equation for predicting the bank profile shape of stable channels.

Dynamic Properties of Sand–Fines Mixtures

Dynamic properties namely shear modulus (G) and damping (h) are input parameters for predicting the ground response of natural soil deposits. The dynamic properties of sands and clays are dependent on many factors such as void ratio, confining pressure, strain amplitude, morphology, and plasticity characteristics. Considerable research has been reported in the recent past by Seed and Idriss (Soil moduli and damping factors for dynamic response analysis, 1970), Hardin and Drnevich (J Soil Mech Found Div ASCE 98(7):667–692, 1972); Seed and Idriss (Ground motions and soil liquefaction during earthquakes. Earthquake Engineering Research Institute, Berkeley 1982), Vucetic and Dobry (J Geotech Eng Div ASCE 117(1):89–107, 1991) and many others on dynamic properties of sands and clays. The factors affecting the dynamic properties of sands and clays are well documented, but soils generally, occur as mixtures of sand, silt and clay in various proportions. There is very little effort made in understanding the dynamic behavior of sand–fines mixtures and therefore there is a need to investigate the dynamic properties of sand–fines mixtures. In the present paper, the results of the behavior of sand–fines mixtures under cyclic loads are discussed. The experimental program consisted of a series of cyclic triaxial shear tests conducted as per ASTM D 3999 (Standard Test Methods for Determination of the Modulus and Damping properties of soils Using the cyclic Triaxial Apparatus. American Society for Testing and Materials 1991) to investigate the strain dependent shear modulus and damping of sand–fines mixtures of different plasticity. Sand was obtained from the Sabarmati river and three types of locally available fines i.e. low-plastic, medium- plastic and bentonite fines were used. Fines content was varied from 15 to 60%. The effect of fines content, plasticity, and relative density on shear modulus and damping is reported. Shear modulus at 0.005% strain level correlates well with the plasticity index for sand–fines mixtures of low to medium plasticity i.e. 0 < IP < 40.

Finite element methodology for the evaluation of soil damping in LNG tanks supported on homogeneous elastic halfspace

Influence of foundation conditions and typology in above-ground full containment liquefied natural gas (LNG) storage tank design makes it necessary to evaluate its structural response due to dynamic actions. Typical above-ground full containment LNG storage tanks are constituted of an outer tank made of reinforced and pre-stressed concrete, which provides support, protection and secondary containment in case of failure of the inner tank and a 9 % Ni steel inner tank, which acts as principal and main containment. Conceptual description of full containment LNG storage tanks is included in applicable normative EN 14620-1. Foundation is a structural element, which acts as a dynamic excitation transmitter in case of earthquakes and modifies structure response. This effect is known as soil-structure interaction due to dynamic energy exchange, which affects the overall structural response. The soil-structure interaction under seismic loads has been implemented on the LNG storage tanks for, at least, the last 30 years. The term is widely used to consider the site effect taking into account the local soil characteristics instead of the simplified approach in a fixed-base analysis. A methodology based on the use of finite element modeling for evaluation of soil-structure interaction under horizontal seismic action is presented and results obtained are compared to methodology included in Veletsos and Damodaran Nair (J Struct Div ASCE 101:109–129, 1975) of characterizing the soil as the standard Voigt solid, which assumes the characteristics of a simulated 1 degree of freedom (DOF) oscillator. Besides, comparison with current formulae extracted from codes EN 1998-1 and ASCE 7-05 will be performed.

Assessment of liquefaction potential of Erzincan Province and its vicinity, Turkey

One of the most important causes of damages after the earthquakes is the soil liquefaction. Liquefaction can be defined as temporary loss in strength of saturated sandy and silty deposits under transient and cyclic loadings due to excess pore water pressure. This study includes determination of liquefaction potential in Erzincan city center and its vicinity. Due to the proximity of the North Anatolian Fault Zone, in a probable earthquake, Erzincan Province is thought to be affected. In this context, the earthquake scenarios were produced using the empirical expressions. Liquefaction potential for different earthquake magnitudes was determined. These earthquake magnitudes were selected as 6.0, 6.5, 7.0, 7.5, respectively. Liquefaction potential was investigated using standard penetration test (SPT) data. The first stage of the study, 63 boreholes in different locations was drilled and SPT was performed. Disturbed and undisturbed soil samples were taken from these boreholes. Laboratory testing was performed to determine physical properties of soil samples, and liquefaction potential analyses were examined using three methods, namely Seed and Idriss (J Soil Mech Found Div ASCE 97(9):1249–1273, 1971), Tokimatsu and Yoshimi (Soil Found 23(4):56–74, 1983), Iwasaki et al. (Soil liquefaction potential evaluation with use of the simplified procedure. International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, St. Louis, pp 209–214, 1981). In order to complete liquefaction analysis within a short time, MATLAB program was prepared. Liquefaction potential analyses were carried out with the MATLAB program. At the final stage of this study, liquefaction potential maps were prepared for different earthquake magnitudes. The expected results will be shared with the local authorities and important engineering remedial measurements will be proposed to prevent further life losses and to mitigate property losses.

Erosion d’une vase de l’estuaire de la Loire sous l’action du courant

Erosion d’une vase de l’estuaire de la Loire sous l’action du courant

Uplift behaviour of pile anchors subjected to lateral cyclic loading. Technical note : Rao, S N; Prasa, Y V S N J Geotech Engng div ASCE V119, N4, Aprila 1993, P786–790

Uplift behaviour of pile anchors subjected to lateral cyclic loading. Technical note : Rao, S N; Prasa, Y V S N J Geotech Engng div ASCE V119, N4, Aprila 1993, P786–790

Tensile reinforcement on bridge-approach settlement : Monley, G J; Wu, J T H J Geotech Engng Div ASCE V119, N4, April 1993, P749–762

Tensile reinforcement on bridge-approach settlement : Monley, G J; Wu, J T H J Geotech Engng Div ASCE V119, N4, April 1993, P749–762

Axial response of tapered piles in cohesive frictional ground : Kodikara, J K; Moore I D J Geotech Engng Div ASCE V119, N4, April 1993, P675–693

Axial response of tapered piles in cohesive frictional ground : Kodikara, J K; Moore I D J Geotech Engng Div ASCE V119, N4, April 1993, P675–693

Constitutive model for cyclic behavior of clays. II: Applications : Desai, C S; Wathugala, G W; Matlock, H J Geotech Engng Div ASCE V119, N4, April 1993, P730–748

Constitutive model for cyclic behavior of clays. II: Applications : Desai, C S; Wathugala, G W; Matlock, H J Geotech Engng Div ASCE V119, N4, April 1993, P730–748

Settlement analysis of layered soil systems by stiffness method. Technical note : Conte, E; Dente, G J Geotech Engng Div ASCE V119, N4, April 1993, P780–785

Settlement analysis of layered soil systems by stiffness method. Technical note : Conte, E; Dente, G J Geotech Engng Div ASCE V119, N4, April 1993, P780–785

Interaction of axial and lateral pile respose. Technical note : Anagostopoulos, C; Georgiadis, M J Geotech Engng Div ASCE V119, N4, April 1993, P793–798

Interaction of axial and lateral pile respose. Technical note : Anagostopoulos, C; Georgiadis, M J Geotech Engng Div ASCE V119, N4, April 1993, P793–798

Settlement of circular and ring plates in very dense calcareous sands : Al-Sanad, H A; Ismael, N F; Brenner, R P J Geotech Engng Div ASCE V119m N4, April 1993, P622–638

Settlement of circular and ring plates in very dense calcareous sands : Al-Sanad, H A; Ismael, N F; Brenner, R P J Geotech Engng Div ASCE V119m N4, April 1993, P622–638

Comparison of rock correction methods for compaction of clavey soils : Houston, S L; Walsh, K D J Geotech Engng Div ASCE V119, N4, April 1993, P763–778

Comparison of rock correction methods for compaction of clavey soils : Houston, S L; Walsh, K D J Geotech Engng Div ASCE V119, N4, April 1993, P763–778

Analysis of deep excavation in Boston : Whittle, A J; Hashash, Y M A; Whitman, R V J Geotech Engng Div ASCE V119, N1, Jan 1993, P69–90

The authors presented a very interesting and informative case history and compared results of predictions and analyses with actual measurements of movements associated with a deep excavation in Boston. Based on their findings, authors state in synopsis of paper that the results demonstrate that reliable and consistent predictions of soil deformation and groundwater flow can be achieved by advanced methods of analysis without recourse to parametric iteration... While mainbody of paper clearly discusses limitations of finite-element anaiyses, because of incomplete and/or inaccurate subsurface data and because of approximations and simplifications in modeling construction sequence, accuracy and reliability of results of such analyses could be misinterpreted from foregoing statement. This Discussion draws attention to some of most significant limitations of analyses and emphasizes need for caution and a good deal of judgment in applying results of such analyses to design.

One-dimensional high-pressure compression of granular media : Hagerty, M M; Hite, D R; Ullrich, C R; Hagerty D.J. J Geotech Engng Div ASCE V119, N1, Jan 1993, P1–18

One-dimensional high-pressure compression of granular media : Hagerty, M M; Hite, D R; Ullrich, C R; Hagerty D.J. J Geotech Engng Div ASCE V119, N1, Jan 1993, P1–18

Fine Ottawa sand: experimental behavior and theoretical predictions : Dakoulas, P; Sun, Y; J Geotech Engng Div ASCE V118, N12, Dec 1992, P1906–1923

Fine Ottawa sand: experimental behavior and theoretical predictions : Dakoulas, P; Sun, Y; J Geotech Engng Div ASCE V118, N12, Dec 1992, P1906–1923

Scaling PSV from earthquake magnitude, local soil, and geologic depth of sediments : Lee V.W. J Geotech Engng Div ASCE V119, N1, Jan 1993, P108–126

Scaling PSV from earthquake magnitude, local soil, and geologic depth of sediments : Lee V.W. J Geotech Engng Div ASCE V119, N1, Jan 1993, P108–126