Seismic Earth Pressure Research Articles

Quantifying Seismic Earth Pressure on Retaining Walls with Relief Shelves Using the Slip-Line Method

Quantifying Seismic Earth Pressure on Retaining Walls with Relief Shelves Using the Slip-Line Method

Calculation method for static and seismic active earth pressure on counterweight retaining walls under translation based on two critical slip surfaces

The counterweight retaining wall with polyline wall back is a kind of gravity walls, which can be alternatively used in high embankments. To completely analyze active earth pressure on the polyline back under the wall translation mode, a comprehensive method is proposed based on two planar slip surfaces in the retained soil, an inclined slice method within the frame of limit equilibrium, and the pseudo-static approach. Meanwhile, the two critical slip surfaces include the global and local ones in the soils behind the whole wall and only the upper wall, respectively; and mobilized shear strength coefficients on interslice surfaces are introduced to fully consider the interslice shear forces. Some examples show that the proposed resultant forces on the whole wall are close to the experimental and numerical results generally within 10% error. The dip angle of backfill surface has a significant effect on the two slip surfaces, and the inclination of the lower back mostly influences the global slip surface. The unloading effect of the platform on the lower earth pressure becomes obvious as the upper wall lengthens under a constant height of the whole wall. The magnitude and profile of the seismic earth pressure on the polyline back are greatly influenced by the seismic coefficients.

The Behavior of Concrete Cantilever Retaining Walls During Far-Field and Near-Fault Earthquakes

Abstract The dynamic behavior of retaining walls is a complicated subject and a considerable design challenge, particularly under seismic conditions. Seismologists and investigators have an interest in near-fault earthquakes with significant velocity pulses because it can cause considerable displacements in constructions with respect to far-field earthquakes and consequently rise the hazard of earthquake-caused failure of structures. Despite there are several studies have investigated the seismic behavior of retaining structures, but the researches about retaining walls subjected to the influence of near fault like pulse earthquakes is still not adequate. The current study targets to numerically assess the dynamic performance of concrete cantilever retaining walls during far field ground motions (FFGMs) and near-fault ground motions (NFGMs). The nonlinear analysis of time history is conducted using the finite element method for three cantilever retaining wall models. The results of the analysis gained in terms of top horizontal displacement of the wall, active seismic earth pressure, and acceleration response of the system, which have been considered to recognize the impact of near fault earthquake on retaining structures. Additionally, the influence of different PGA of NF and FF earthquakes has been studied.

Influence of the anchor angle on the seismic response of anchored stabilizing piles: Centrifuge modeling tests

Anchored stabilizing piles (ASPs) are widely used as excavation support systems in slope anti-seismic reinforcement engineering. In this study, a set of centrifuge contrast tests were designed and used to explore the influence of the anchor angle on the seismic response of the system to further deepen the research on the seismic response of ASPs. To this end, the effects of two anchor cable arrangement angles on the slope seismic response, lateral dynamic earth pressure, anchor cable axial force, and pile dynamic moment were compared and analyzed. The results show that changing the angle of anchor cable arrangement can reduce the degree of seismic damage to the slope and the settlement of the slope top (up to a maximum reduction of 77%) and, to some extent, reduce the amplification of acceleration inside the slope. Under seismic action, the different angles of anchor cables do not change the distribution of seismic earth pressure and peak dynamic bending moment but can significantly affect their magnitude and growth rate. The appropriate arrangement angle of the anchor cable can effectively slow the growth of the internal force of the anchor cable and reduce the risk of anchor cable failure. The anchor cable is not the main load-bearing component in an ASP but the primary component that limits pile displacement. Overall, this study can provide a detailed data foundation for subsequent centrifuge comparative tests and parameter analysis.

Seismic earth pressure acting on semi-underground structures considering cyclic behavior of soil ground

Seismic earth pressure acting on semi-underground structures considering cyclic behavior of soil ground

Analysis of Seismic Earth Pressure Acting on Basement Walls of Buildings Using 1g Shaking Table Model Test

Analysis of Seismic Earth Pressure Acting on Basement Walls of Buildings Using 1g Shaking Table Model Test

Seismic Behavior of Retaining Walls: A Critical Review of Analytical and Field Performance Studies

Given the abundance and importance of earth retention structures, the problem of seismic earth pressure has attracted not only the research community but also industry and government establishments. The dynamic response, even in the case of the simplest retaining wall, presents a complex problem of soil–structure interaction, encompassing a multitude of competing and complementary factors. This article presents a thorough and critical evaluation of notable analytical and field studies related to the dynamic earth pressures acting on retaining walls. Despite numerous studies spanning nearly a century regarding seismically induced lateral earth pressures, there remains a noticeable disparity between theoretical understanding and the actual field performance of retaining structures during seismic events. This review underscores the necessity for a more meticulous examination of dynamic analysis techniques and the existing design methodologies for retaining structures.

Probabilistic assessment of seismic earth pressure against backfills with a nonlinear failure criterion

A novel approach for the probabilistic assessment of seismic earth pressure against nonlinear backfills is introduced in this study. To implement reliability-based design for the retaining structures under seismic loading condition, nonlinear upper bound analysis is adopted to obtain the seismic earth pressure through optimization procedure. Firstly, rigorous analytical function is formulated to reveal the normal-shear stress information along the failure surface in soil with nonlinear failure criterion. Subsequently, a kinematic equation is put forward to estimate the seismic earth pressures by balancing the external work rate and the internal energy dissipation rate. The solutions are verified by the Discontinuity Layout Optimization numerical modellings based on the derived stress data from the proposed method. To consider the probability analysis of nonlinear backfill properties, the moment method is presented by combining the adaptive dimension decomposition with the direct integral method. According to the estimated first four statistical moments, the approximated probability density function of the performance function is determined contently. Finally, the failure probability of seismic earth pressure is calculated based on the proposed moment method. Two numerical examples demonstrate that the moment method can be adapted to the characteristics of nonlinear backfills and further improve the accuracy of reliability estimation by introducing higher-order moments analytically.

Mechanism of Seismic Earth Pressure on Braced Excavation Wall Installed in Shallow Soil Depth by Dynamic Centrifuge Model Tests

Mechanism of Seismic Earth Pressure on Braced Excavation Wall Installed in Shallow Soil Depth by Dynamic Centrifuge Model Tests

A parametric study on the dynamic lateral earth forces on retaining walls according to European and Turkish Building Earthquake Codes

In the earthquake regulations of many countries, Mononobe-Okabe method was used to determine the seismic lateral earth forces and earth pressure coefficients for the design of retaining structures. However, there are various interpretation differences of this method between earthquake regulations of different countries. In this study, effect of different seismic acceleration coefficients (S_DS) and different soil friction angles(ϕ_d^,) on the seismic earth forces acting on a high retaining structure were investigated through a parametric study based on the methods described in 2018 Turkish Building Earthquake Code (TBEC-2018) and EuroCode-8 (EC-8). For this purpose, approximately 120 analyzes were carried out by using different parameters and the analysis results were shown in tables and figures. Analyses were performed for yielding rigid retaining walls and anchored walls for the principles defined in the mentioned earthquake codes. It was observed that the seismic lateral force estimations made with TBEC-2018 are higher compared to values calculated according to EuroCode-8. In the calculation of dynamic thrust, unexpected results may occur at some critical values of θ angle which is dependent on the lateral acceleration coefficient.

Estimation of seismic passive earth pressure coefficients for caissons in c-φ soils with a 3D log-spiral failure wedge

Passive resistance offered by soil to any embedded structure has been of significant interest to researchers since the inception of the concept. The present study deals with the estimation of passive earth pressure coefficients in seismic conditions that will control the passive resistance offered to a caisson embedded in c (cohesion) – φ (friction) soil in presence of surcharge loading. The three-dimensional (3D) geometry of failure wedge (log-spiral in vertical plane and oval in horizontal plane) has been obtained from the results of numerical analysis and past experimental studies. The critical failure surface has been obtained in the presence of all resisting components [unit weight (γ), cohesion (c) and surcharge (q)] by minimizing the passive resistance. Thereafter, seismic passive earth pressure coefficients for cohesion component (Kspc), surcharge component (Kspq) and unit weight component (Kspγ) have been obtained separately corresponding to the critical failure wedge obtained in the previous analysis. Limit equilibrium method of analysis in conjunction with pseudo-static approach has been used to perform the analyses. Charts for a variety of caisson geometry, soil and site condition and seismic condition have been prepared to facilitate prediction of passive resistance in a more economical and reliable manner since unique failure wedge has been considered for all the components instead of separate failure wedge which would be impractical.

Seismic performance of U-shaped spillway retaining wall from shake table tests

A series of large-scale shake table tests were performed to evaluate the seismic behavior of a U-shaped spillway retaining wall. Three test model configurations were employed using different backfill conditions in terms of in-place soil density. Two earthquake records were employed as input motion and scaled in terms of time duration and acceleration amplitude to assess various aspects of seismic response. The test results showed that dynamic wall deflection and wall bending moment generally increased with Peak Ground Acceleration (PGA) amplitude. At peak wall deflection, the seismic earth pressure increment coefficient (ΔKAE) was back-calculated from the measured bending moment along each wall. In addition, the location of ΔKAE along the wall height and the resulting base moment were evaluated and discussed. The results suggested that seismic demands were generally lower up to a PGA of about 0.8 g, compared to the classic Seed and Whitman recommendation for seismic lateral earth pressure and seismic bending moment of retaining walls. Beyond PGA of 0.8 g, test results were in general agreement with the Seed and Whitman solution. Finally, two-dimensional finite element analyses were performed, and the computational results showed overall reasonable agreement with the experimental data.

Seismic passive earth pressure resistance for caisson in layered soil using modified pseudo‐dynamic approach

AbstractThe determination of seismic passive earth pressure resistance is of utmost importance during the analysis of geotechnical structures. In the present study, seismic passive earth pressure coefficient for caisson embedded in n‐layered soil is computed using modified pseudo‐dynamic method. Limit equilibrium method of analysis considering poly‐planar failure wedge has been adopted in the study and parametric variation of geometry of failure wedge has also been studied. The current study proposes formulation for variation of horizontal and vertical seismic acceleration profile with depth through various layers and studies the effect of number of layers, relative depths of various layers and relative soil friction angle in those layers, soil‐wall friction angle, horizontal and vertical seismic acceleration coefficients and normalized width of caisson. The study has been extended for submerged soil and the effect of excess pore pressure has been investigated. The results of the present study have been compared with previous theoretical studies and found to be in good agreement. It is observed that the extent of failure wedge formed in front of caisson increases with increasing soil friction angle, soil‐wall friction angle, horizontal seismic acceleration coefficient and width of caisson.

Dynamic Characteristics of Reinforced Soil Retaining Wall with Composite Gabion Based on Time Domain Identification Method

A series of shaking table tests was carried out on the dynamic performance and working mechanism of a gabion reinforced soil retaining wall under seismic load. The test results show that the panel presents the deformation mode of middle and upper bulging at the contact point between the rigid box and the retaining wall The settlement of top backfill is relatively uniform, and there is basically no differential settlement, the natural frequencies at different positions and heights inside the retaining wall are basically the same, and the natural frequencies are stable between 22.61 and 23.04 Hz below 0.8 g. The damping ratio decreases with the increase in wall height, and the damping ratio at each stage after vibration is greater than that before vibration. The seismic earth pressure is nonlinearly distributed. The measured value of the lower part of the retaining wall is smaller than that calculated by the Seed–Whitman method with an increase in peak acceleration, and the measured value of the upper part of the retaining wall is larger than the theoretical calculation results. The position of the resultant action point of seismic earth pressure is greater than 0.33 times the wall height specified by the Mononobe–Okabe method.

Seismic Stability Analysis of Caissons under Earthquake Forces Considering 3D Log-Spiral Failure Surface

Bridge failure is mostly caused by geotechnical failure. Because caissons are the automatic choice for foundation systems for marine structures, such as bridges and wind turbines, this study addresses the determination of seismic passive earth pressure coefficients for caissons. In the present study, a realistic three-dimensional (3D) failure wedge was assumed to be formed behind caissons of different widths on the basis of the past results of experimental and numerical studies. The limit equilibrium method of analysis was adopted to determine the seismic passive earth pressure coefficients due to the cohesion component, surcharge component, and unit weight component. The current study takes into account the relative width and depth of the geotechnical structure and returns a series of design charts and tables for different soil-soil friction angles, soil-wall friction angles, and horizontal and vertical seismic acceleration coefficients. The results were compared with previous experimental and theoretical studies and found to be in excellent agreement.

A closed-form logarithmic spiral method for seismic passive earth pressure in anisotropic sand

The shear strength of soils is always anisotropic due to the compaction and deposition history. A closed-form logarithmic spiral method combined with an anisotropic failure criterion is proposed to estimate the seismic passive earth pressure coefficient and failure surface of anisotropic sand. The seismic condition is implemented by the pseudo-static approach. The results obtained by the proposed method are validated by methods in the literature and by the finite element method based on a proposed anisotropic Drucker–Prager model. The comparisons show that the method is effective and efficient. In addition, the seismic passive earth pressure coefficients considering various backfill slopes and various soil-wall frictions are presented for reference in engineering design.

An Improved Method of Vertical Slices to Determine Seismic Passive Earth Pressure and Its Point of Application

This paper presents a new approach for calculating seismic passive earth pressure, its point of application, and the approximate stress-state within the rupture wedge. The method of vertical slices combined with the limit-equilibrium (LE) technique was used as the framework for the analysis. While the available LE analyses used the rupture surface of predefined shapes, in this approach, the rupture surface is derived through the analysis. First, the mobilized soil behind the wall was split into thin vertical slices and the rupture plane of every slice was calculated by enforcing the Mohr–Coulomb failure criterion. Thereafter, by adding those rupture planes consecutively, starting from the wall toe, the passive rupture surface was achieved. The inclination of the rupture planes is guided by the soil friction angle, wall friction angle, seismic acceleration, and slice-interface friction angle. The distribution of slice-interface friction angle across the rupture plane was presumed to obey a power function. The exponent of the power function, the seismic passive earth pressure, and its point of application were derived concurrently by satisfying the static equilibrium conditions of the slices and applying a boundary condition. The results show that the outline of the rupture surface is guided by the slice-interface friction angle, and the shape is curvilinear for rough walls. With increasing seismic acceleration, the passive pressure decreases, and the point of application moves predominantly downward for loose sands. The obtained results were compared with those of previous numerical and experimental studies and were found to show good agreement, thus demonstrating the validity of the proposed method.

Analytical approach for kinematic FCRW–soil interaction in multi–layered soil under earthquake loads

A closed form solution for FCRW (flexible cantilever retaining wall)–soil interaction under seismic condition is proposed for a layered soil profile. The displacement function of the FCRW and the attenuation function of the kinematic FCRW–soil interaction are obtained in the coupled form based on the Hamilton's principle. Then an iterative procedure is applied to solve the coupled functions. There are three main contributions of the proposed model: (1) the kinematic FCRW response in layered soil system is analyzed based on an analytical method; (2) the soil continuity effect is taken into account; (3) the kinematic FCRW–soil interaction in layered soil is quantitatively analyzed. The results highlight that the soil stiffness discontinuity significantly influences the contribution of the different physical mechanisms (e.g., FCRW rigidity, Winkler spring and soil continuity) in kinematic FCRW–soil interaction. The results also show that the soil stiffness discontinuity may exponentially amplify the seismic earth pressure and kinematic FCRW response.

Passive earth pressure of vegetation rooted soils based on limit analysis and quasi-static approach

Although it has been recognized that vegetation roots have a positive effect on the stability of geotechnical structures, few quantitative studies have been performed on the effects of vegetation roots on earth pressures. In this paper, based on the upper bound limit analysis theory and quasi-static method, a new method for calculating the seismic passive earth pressure of vegetation rooted soils is proposed, which considers both the hydrological and mechanical effects of vegetation roots on the passive earth pressure. The proposed method is validated by some existing solutions. The effects of root parameters of shrubs (root transpiration rate, root tensile strength, and root depth), angle of the soil slope surface with the horizontal, and wall interface friction angle on the seismic passive earth pressure coefficient are also investigated. The results show that the passive earth pressure coefficient increases with the increase of root transpiration rate, root tensile strength, root depth, angle of the soil slope surface with the horizontal, and wall interface friction angle. Compared with the mechanical effect, the hydrological effect of vegetation roots on the passive earth pressure coefficient is more obvious. The effects of root parameters on the passive earth pressure ranked in descending order of sensitivity are root transpiration rate, root tensile strength, and root depth. In addition, the effect of vegetation roots on the passive earth pressure becomes more significant with the increase of internal friction angle. The proposed method can provide a reference for the local reinforcement of multi-stage slopes with vegetation.

A Study on the Seismic Passive Earth Pressure on Rigid Retaining Walls Considering Seismic Acceleration Field

ABSTRACT The seismic passive earth pressure is typically calculated by a pseudo static analysis by the PGA on the ground surface which is often assumed to be constant within the soil mass. This may result in an underestimation of the limit load. On the other hand, variations of the acceleration field over time and space render the interpretation of the seismic limit load either very difficult, if a complete elasto-plastic solution is sought at each time step, or argumentative. A rather new procedure is presented in this study which considers the variable seismic acceleration field behind a rigid retaining wall during an earthquake and applied to a series of acceleration time histories. The method of stress characteristics is implemented to estimate the limit load at each time step. This method seems to be more convenient with a clear interpretation of the actual limit load. Results indicated that the conventional pseudo static analyses provide an over-conservative estimate or an underestimation of the passive earth pressure.