International Journal of Geomechanics

The joint structure between the asphalt concrete core and the concrete plinth is a critical and vulnerable part of the asphalt concrete core dam (ACCD). Shape parameters of the core–plinth joint structure are directly related to joint structure behavior and thus affect the core safety, but there is currently a lack of relevant quantitative research. In this paper, the shape parameters of the joint structure were optimized to obtain an economical joint form under the condition of ensuring the stress safety of the joint structure. Abutment slope ratio i, core enlarged angle θ, and depth of the core embedding into the plinth h were taken as optimization parameters. The maximum shear stress, maximum tensile stress, and minimum arch effect of the core were taken as constraint conditions, and the joint structure volume was taken as the objective function to establish a mathematical optimization model for the joint structure. The regression relationship between the constraint conditions and the joint structure parameters was fitted based on the central composite design and response surface method. A three-dimensional zone of joint structure parameters that can satisfy the constraints was further constructed. Combined with the linear programming method, an optimization calculation method for joint structure parameters was proposed. Taking the dam with the highest core among the ACCDs that have been built as an engineering example, an optimization analysis of the joint structure between the core and plinth was conducted. The results indicated that the stress and the arch effect of the joint structure improve as the abutment slope becomes gentler. As h increases, the arch effect and shear stress at the joint weaken. The increase in θ will increase the possibility of core shear failure and make the core suffer a stronger arch effect. Compared with the original engineering (θ and h are 75.96° and 0.3 m, respectively), when the θ and h are set as 80° and 0.39 m, the joint structure volume reduces by 6.67% under the condition of i of 1:0.33, which can achieve better economic efficiency under the premise of satisfying the core safety.

The discussion about the seismic behavior of prefabricated rectangular underground structures is mainly focused on the specific structure form, and there is a lack of a more extensive and regular discussion from the theoretical point of view. In this study, a simplified analytical solution of racking ratio–flexibility ratio (R-F) relationship for prefabricated rectangular underground structures is proposed. This solution assumes that the seismic action on deep underground structures can be reduced to far-field shear action. A numerical model verifies the feasibility of this solution. The suggested evaluation index of the rock model of the prefabricated rectangular underground structure is presented. The results show the simplified calculation theory is accurate, especially for structures with an F greater than 1; the error is less than 10%. The rotation of the column midpoint can be used as the estimation result of the rock mode of the prefabricated structure. When two structures have the same F, the R of the prefabricated structure is more diminutive.

Helical piles are widely used for their low installation noise, low disturbance, recyclability, and increased load-bearing capacity. This study investigated the effects of installing multiple-plate helical piles on the surrounding soil using the coupled Eulerian–Lagrangian finite-element method. The comprehensive parametric study was carried out using the advancement ratio, the spacing ratio, the ratio of helix plate diameter to shaft diameter, the embedment depth ratio, and the soil strain softening parameters. The influence on the uplift capacity was then investigated by mapping the remolded soil strength field, derived from the coupled Eulerian–Lagrangian computation, into a numerical model for finite-element limit analysis. The results reveals that the penetration of single- and multiple-plate helical piles affects the soil strength in a cylindrical region with a radius of 0.7 times the helix plate diameter and a height of the penetration depth surrounding the pile. Although strain softening parameters have a significant impact on soil strength, they do not alter the range of soil strength disturbance. The impact of embedment depth ratio on uplift bearing capacity is most notably significant.

To investigate the pressure-relief and permeability enhancement mechanisms of hydraulic flushing (HF), this study conducted the triaxialseepage experiments on raw coal; the permeability changes during the loading process were analyzed, and the coal permeability evolution model was derived considering the damage effect. Given the boundary conditions of gas seepage and stress fields, a multifield coupling model was developed to reflect coal seam methane (CBM) extracted by the HF borehole. Based on the actual geological conditions of Yi'an Coalmine, the three-dimensional (3D) numerical simulation was implemented to investigate the effects of coal discharge amount on the relief range, coal permeability, and effective extraction radius of the HF borehole. Moreover, the validity of the coupling model was confirmed through field tests on hydraulic flushing. Then, the interactions of various factors, including coal discharge amount, borehole spacing, initial CBM pressure, and coal permeability, were investigated using the response surface methodology (RSM). Through the results obtained, it was found that the interactions between the factors involved were very significant and caused an obvious time effect on CBM extraction. The interaction between coal discharge amount and borehole spacing increasingly affected the extraction effect of HF boreholes, whereas the interaction between initial CBM pressure and coal permeability gradually weakened. Then, the RSM regression model was established to optimize the borehole placement parameters using predicted extraction time and coal discharge amount as variables. The regression prediction data were consistent with the simulation results and mutually validated. Therefore, based on the elimination of gas outbursts and reduced construction costs, the modeling approach and the RSM model introduced in this study can be used to optimize the precise placement parameters of HF boreholes for enhancing CBM recovery within the expected extraction period.

Abstract

Rock structures and load conditions play a considerable role in the deformation and failure process of rocks. To explore the nonlinear mechanical mechanism of brittle rocks, this study presents the extreme entire life constitutive equation, breakage equation, and rock resistance breakage energy (RBE) equation of limestone specimens under unequal amplitude cyclic loads. The theoretical model is based on the calculus method and thermodynamic principle, and the Helmholtz free energy of a rock system after the action of a composite system is nonlinearly separated. The extreme entire life constitutive equation of limestone is deduced on the basis of analytical solutions of nonlinear separation parameters and breakage evolution, whereas the breakage equation is deduced on the basis of the principles of residual breakage energy and thermodynamics. We present the analytical solution of the material RBE, which reflects the ability of rocks to resist breakage under load. The model performance is verified by limestone samples with different prefabricated cracks under unequal amplitude cyclic loading. This research may lay the foundation for studies of nonlinear breakage models under different conditions.

Practical Applications

The study investigates a theoretical model derived from the coupling of nonlinear separation of Helmholtz free energy and breakage evolution. It is discovered that the entire lifespan of complex natural objects, caused by the timely evolution of breakage, can be represented by the nonlinear separation of Helmholtz free energy. An analytical solution for Helmholtz free energy considering nonlinearity and breakage is proposed. Additionally, an equation in the theoretical model is presented to reflect the law of constitutive mechanics governing the entire lifespan of brittle rock materials. Based on the principles of residual breakage energy and thermodynamics, we provide an analytical solution for material resistance breakage energy, which represents the ability of brittle rocks to resist breakage under load. The model is validated using limestone samples with different prefabricated cracks under unequal amplitude cyclic loading. This study establishes a foundation for exploring nonlinear breakage models across various conditions and offers theoretical guidance for enhancing the safety and stability of engineering structures.

The deformation and ultimate bearing capacity of a high arch dam are the key issues in the impoundment period of hydropower stations. In this paper, the ultimate bearing capacity and failure mode of the arch dam of the Dagangshan Hydropower Station are studied by means of field monitoring, theoretical analysis, and numerical simulation. The cusp catastrophe theory is innovatively applied to the study of the ultimate bearing capacity of an arch dam. The failure process and mode of the arch dam are explored from the macro and micro perspectives. The results show that: (1) the radial displacement of the arch dam reaches the maximum at the dam axis position under different water levels, and the tangential displacement reaches the maximum at the 1/4 position on the left and right sides; (2) the high stress area of the arch dam shifts from the toe to the heel when the water level decreases; and (3) the comprehensive stability safety coefficient of arch dam is 5.375–5.625 based on the comprehensive method, and which is 5–5.375 based on the cusp catastrophe model. The left and right ends of the arch dam crest elevation and the left and right sides of the dam heel are the first to crack under different comprehensive stability safety coefficients. The research results have a guiding significance for the safe operation and protection of hydropower station arch dams.

This study aims to establish an objective analytical framework for determining the number of boreholes that are essential for addressing soil slope design challenges in diverse geological/geotechnical settings. This study utilizes the covariance matrix decomposition method and a two-directional one-dimensional Markovian covariance function to create a two-dimensional random field. A Monte Carlo simulation is used to assess the statistical response based on the generated random fields. A random limit equilibrium method (RLEM) code in MATLAB (version R2023a) is developed using circular slip surfaces equipped with a chaotic particle swarm optimization technique for the reliability analysis of soil slopes. Additionally, the strength reduction method based on the finite difference/finite-element (FE) techniques is adopted to compare the reliability analysis results, such as the probability of failure (P_f). A new programming strategy is adopted to simulate the spatial variability in the FE soil slope model and calculate the factor of safety using a gradient of the maximum slope displacement. Bayesian updating is applied to adjust the conditional probabilities of decision variables and the component reliability. The strategic deployment of boreholes at the toe, middle, and top of the slope results in a significant reduction in the estimated P_f according to the RLEM, the random finite difference method (RFDM), and random FEM (RFEM) analyses. However, employing subsequent boreholes does not proportionally decrease the P_f. The influence of the horizontal autocorrelation distance (ACD) on the P_f is explored, showing that as the horizontal ACD increases from 10 to 20 m, the estimated P_f for the three boreholes decreases to 19% and 13% in the RFEM and RLEM, respectively. This reduction becomes less pronounced, dropping to 4% and 1.3%, respectively, when the ACD increases to 30 m.

As an effective reinforcement technology for seepage prevention, penetration grouting has been widely used in geotechnical and underground engineering. Because grouting is a hidden project, the extent of slurry spread is often estimated theoretically and through experience. Therefore, it is important to understand the diffusion pattern and scope of penetration grouting in reinforcement engineering. Based on the generalized Darcy's law, a penetration grouting model considering the gravity and the time-varying nature of the slurry viscosity is proposed in this study. Its validity and effectiveness are verified through a comparison with existing penetration grouting tests. Based on the established penetration grouting model, the effects of the grouting pressure, permeability coefficient, water–cement ratio, and other factors on penetration grouting are analyzed. The penetration and diffusion process of a Bingham fluid considering gravity and time-variable slurry viscosity is computationally simulated using a finite-element software. The research results show that the proposed penetration grouting model is more accurate than the traditional one that does not consider the two aforementioned factors, and its results are more in line with the experimental ones. The rate of error calculated from the experimental value is about 11%. The diffusion radius of the slurry increases with increasing grouting pressure, permeability coefficient, and water–cement ratio, and decreases with increasing groundwater pressure. With the elapse of the grouting time, the increase rate of the diffusion radius exhibits a trend of increasing first and then decreasing and tending to level off. These research results can provide certain theoretical support for penetration grouting research in geotechnical and underground engineering.

The soil–cement deep soil mixing (DSM) technique has been widely used to improve the bearing capacity of the soft soil under embankment loading. However, utilizing ordinary portland cement (OPC) releases a tremendous carbon footprint. Industrial waste–based geopolymer has emerged as a sustainable and environmentally friendly solution for stabilizing soft soils. This work investigates the behavior of embankment models constructed on geopolymer-stabilized soil columns (GPSCs) under static and cyclic loading conditions similar to transportation routes. A series of static and cyclic loading tests were carried out on the reduced-scale designed embankment model resting on soft soil (c_us = 5 kPa) reinforced with end-bearing (l/h = 1) and floating (l/h = 0.75) GPSCs with area replacement ratios (A_r) of 12.7%, 17%, and 21.2% to analyze the vertical stress–settlement behavior of the improved ground. Earth pressure cells were used to measure the vertical stress on the column and the adjacent surrounding soil under static and cyclic embankment loading. A pore-pressure transducer was used to monitor the excess pore-water pressure generated during the loading process. The results indicate that the ultimate bearing capacity (q_ult) improvement for end-bearing GPSCs was 246.92%, 344.56%, and 418.8%, whereas the improvement for floating GPSCs was 126.9%, 151%, and 181.64% for A_r values of 12.7%, 17%, and 21.2%, respectively. Furthermore, the stress concentration ratio increases and excess pore-water pressure decreases with increasing A_r and l/h ratios. A mathematical equation was also derived to determine the q_ult value with A_r and l/h ratios. End-bearing GPSCs were more effective than floating GPSCs at the same A_r under static and cyclic loading. For installing floating GPSCs, a higher area replacement ratio is required for better load bearing under static and cyclic loading. In addition, a life cycle assessment of the geopolymer compared to OPC was performed, showing that the geopolymer is a sustainable and eco-friendly construction material.

The shear strength of sand is important to the design and modeling of shield tunneling, and the tangential adhesion strength is a key parameter when determining the pressure gradient along the screw conveyor, the clogging of soil, and the abrasion of the cutting tools. This paper brings up an accurate vane and plate shear test device, which could increase the accuracy of measurements by quantifying and eliminating the influence of torque fluctuation. The peak and residual values of the shear strength and tangential adhesion strength are measured at atmospheric pressure, with water contents from 0% to 25%, and rotation speeds from 0 to 5 r/min. The test results demonstrate that the peak values increase to a maximum value and then decrease with water content. The water content that corresponds to the maximum peak value was between 5% and 20%; the finer the sand, the higher the water content. The ratio between the tangential adhesion strength and shear strength (ratio α) decreases with water content, from approximately 0.7 at a water content of 0% to approximatley 0.4 at 25%. The vane shear test reaches a peak value within 0.17 rotations, and the plate shear test reaches a peak value between 0.25 and 0.55 rotations. Both tests reach residual values after five full rotations. In addition, finer sands have higher shear strengths and higher ratio α.

Prevalent models addressing wellbore stability typically oversimplify the borehole wall, characterizing it as either perfectly permeable or entirely impermeable. However, the widely observed behavior of a shale borehole, permitting solvent molecules, while restricting solutes, underscores the necessity of recognizing the borehole wall as a nonideal semipermeable medium—a medium that selectively allows certain molecules to pass through, while blocking others. This paper presents a poroelastic solution for a semipermeable borehole subjected to nonhydrostatic stresses within a fluid-statured transversely isotropic medium. The analytical solutions in the Laplace domain are derived through the combined application of integral transform and load decomposition techniques. Numerical examples are presented to explore the influence of both semipermeability and material anisotropy on temporal evolution of pore pressure and poroelastic stresses surrounding the wellbore. The results show that, for a semipermeable wellbore under Mode 2 loading, which accounts for perturbations in pore pressure, changes in Young’s modulus ratio and Poisson's ratio have minimal influence on the distribution of pore pressure surrounding the wellbore. However, the circumferential stress exhibits a high sensitivity to alterations in Young’s modulus ratio and Poisson's ratio. The impact of mechanical anisotropy on circumferential stress becomes increasingly significant as time progresses. In contrast, for a semipermeable wellbore under Mode 3 loading that accounts for deviatoric stresses, both mechanical anisotropy and borehole semipermeability significantly shape the pore pressure near the wellbore at early times, while mechanical anisotropy does not noticeably affect circumferential stress. Additionally, the results underscore a noticeable disparity in the stress and pore pressure fields predicted by the semipermeable model in comparison with both permeable and impermeable borehole models. This highlights the importance of considering the nonideal semipermeable nature of shale boreholes in wellbore stability analyses.

Mechanically stabilized earth (MSE) retaining walls have been successfully implemented in numerous applications, particularly where dynamic loads such as earthquake and traffic loading are prevalent. However, using MSE walls as foundations for high-speed train track systems remains uncertain, and their performance under high-speed train loading is inconclusive. This paper extensively investigates the behavior of MSE walls under various high-speed train loading conditions, addressing key considerations, challenges, and findings. The study focuses on evaluating wall performance in terms of horizontal displacement, settlement behind the facing, tensile load and displacement of reinforcement elements, and wall amplification characteristics. The performance of the wall is also assessed by examining the influence of the cement asphalt mortar layer. The total axle load and loading duration are identified as critical design parameters for high-speed train loading, and an empirical equation is developed to estimate horizontal wall displacement based on these parameters.

Hanging sleepers, which result from the differential settlement of the ballast layer, are a prevalent issue that leads to the rapid degradation of track components that include the ballast, sleeper, fastener, and rail. A novel type of sleeper, the wedge-shaped self-leveling sleeper (WSS), was proposed as a solution to the hanging sleeper problem. The WSS leverages the train’s dynamic loading and the gravity of the ballast to naturally allow the ballast particles to fill the gap between the ballast and the sleeper. This paper focuses on the dynamic performance of the WSS from different aspects, which include wedge angles (30°, 45°, and 60°), sleeper materials (concrete and plastic), and the number of WSS to replace regular sleepers in the transition zone. A series of numerical modeling [which coupled multibody simulation (MBS) and discrete-element methods (DEM)] were conducted to design, optimize, and test the WSS. The results reveal that a concrete WSS is well-suited to address the problem of hanging sleepers in transition zones. The WSS with a 45° angle demonstrated superior performance compared with other types of WSS. Importantly, the WSS could reduce vibrations in the vehicle and track, even when dealing with hanging sleepers. Due to the self-leveling function, the WSS shows significant promise for applications in transition zones, which could reduce the frequent need for track geometry maintenance.

The constitutive model in geotechnical engineering plays a critical role, driving the need for ongoing research and improvement. In this study, by utilizing a single yield curve and only one hardening parameter, a nonorthogonal elastoplastic (NOEP) constitutive model for the overconsolidated (OC) clay is established within the framework of the NOEP model. The nonorthogonal plastic flow rule, based on the Riemann–Liouville fractional derivative, was employed to determine the plastic flow direction, which is nonorthogonal to the improved yield curve. Furthermore, a novel hardening parameter is proposed to capture the magnitude of plastic strain increment for OC clays. This is achieved by comparing deformation behaviors in OC clays with two distinct degrees of overconsolidation. Additionally, it is further enhanced by the integration of a newly proposed potential stress ratio. The proposed model requires only eight parameters, and its performance is evaluated by its predictions with test results for OC clays subjected to drained or undrained triaxial stress conditions. This study is expected to offer valuable insights and a better approach toward understanding and capturing the deformation behaviors of OC clays.

Predisintegrated carbonaceous mudstone (PCM) that exhibits low strength and continuous disintegration is prone to wetting deformation after repeated seasonal rainfall. A reasonable assessment of wetting deformation is required to facilitate the settlement control of the PCM embankment when exposed to repeated rainfall. Herein, to reveal the wetting deformation mechanism of the PCM subjected to drying–wetting cycles, the effects of drying–wetting cycles on the wetting deformation characteristics of the PCM are investigated using the double-line method. Microscopic pore characteristics of the PCM under different drying–wetting cycles were analyzed through scanning electron microscope (SEM) micrographs. Comparative analysis of the wetting deformation data between the tests and the constitutive model considering the damage of drying–wetting cycles was carried out. The results showed that the deviator stress–strain relationship curves of the PCM exhibit the strain hardening without obvious peak and no strain softening phenomena. The critical wetting strain of the PCM was positively correlated with the number of drying–wetting cycles, while the critical deviator stress decreased with an increase in the number of drying–wetting cycles. As the number of cycles increased, the gelling material between the particles dissolved, the volume of pores inside the PCM increased, and the number of pores inside the PCM decreased. The porosity of PCM had a significant quadratic function with the number of drying–wetting cycles. A wetting deformation damage model was developed to calculate the wetting deformation of the PCM by considering the effects of drying–wetting cycles, which can be useful for evaluating rainfall-induced settlements of relevant engineering structures made from PCM.

The seepage behavior of a single fracture under the coupled shear–seepage condition is important to the stability of rock mass, especially when shear broken. In this study, coupled shear–seepage tests are conducted on regular tooth single rock fracture with radial fluid flow. The shear failure and changes in the dilation angle were investigated with 1.27, 1.59, 1.91, 2.23, and 2.55 MPa normal stress; the nonlinear seepage behavior was analyzed with 0.2, 0.4, 0.6, and 0.8 MPa hydraulic pressure, and shear broken. The results show that during the shearing process, the nonlinear changes in shear strength, normal deformation, and the dilation angle show great differences with shear displacement, which could be divided into the peak shear, softening shear, and residual shear displacement sections under the influence of shear broken and gouge material. In the peak shear displacement section, normal deformation increased rapidly when the dilation angle was constant; in the softening shear displacement section, normal deformation increased slowly when the dilation angle rapidly decreased, and the normal deformation and dilation angle tended to be stable in the residual shear displacement section. The relationship between the hydraulic gradient and flow rate was consistent with Forchheimer’s law, and the linear and nonlinear term coefficients in Forchheimer’s law show a negative power and negative exponential function with shear displacement, because the joint surface roughness and the degree of the uneven aperture decreased with the influence of shear broken and gouge material. In addition, the values of the mechanical aperture were much larger than the hydraulic aperture, the ratio between the mechanical and hydraulic apertures increased, and decreased nonlinear taken peak shear displacement as the dividing point. Finally, the nonlinear dilatancy seepage model was established by considering the changed dilation angle and hydraulic gradient during the shear process. This study could be a basis for the coupled shear–seepage analysis of network rock mass and similar studies.

Frequent earthquakes, coupled with discontinuous geological conditions, complicate the earthquake dynamic response characteristics of slopes. To reveal the dynamic accumulative damage effect and instability mechanism of a cross-jointed rock mass slope under continuous earthquakes, two discrete-element models, a homogeneous slope and a cross-jointed slope, are established in this study via particle flow code (PFC2D). The results show that the cross-jointed slope has an obvious dynamic amplifying effect on the elevation and slope surface. Compared with the homogeneous slope, the cross-jointed slope has a more significant slope magnification effect. The seismic wave amplification on cross-jointed slopes is more significant under the influence of S waves than P waves. In addition, on the basis of the characteristics of crack propagation and particle bonding failure, the dynamic cumulative failure effect and evolution process of cross-jointed slopes under cumulative earthquakes are revealed, including the crack initiation stage (≤0.1g), crack accumulation stage (0.1–0.2g), crack propagation stage (0.2–0.4g), and crack penetration stage (0.4–0.6g). Through the analysis of particle bond rupture characteristics and displacement evolution, the mechanisms of dynamic failure and modes of instability for the cross-jointed slope are identified. Under a small earthquake (≤0.2g), the slope remains largely uncracked, and slope failure does not occur. Under a strong earthquake (≥0.4g), bond failure near the slope surface develops rapidly and intensively, and the sliding body gradually experiences instability failure. Moreover, joints control slope dynamic failure behavior. Shear failure and tensile failure mainly occur in cross-jointed slopes and homogeneous slopes, respectively.

The compressibility of saline soil is crucial to infrastructure construction in saline areas. In the present study, oedometer tests were conducted on samples of artificial saline clayey sand with varying salt content to study the compressibility of saline soil in northwest China. The initial void ratio formula for saline clayey sand was proposed to account for changes in salt concentration and the condition of the salt phase by theoretical analysis of the three-phase sketch. To validate the proposed formula, nuclear magnetic resonance was employed to evaluate the pore size distribution for three distinct salt concentrations, both quantitatively and qualitatively. An elastoplastic compression model was utilized to analyze the evolution rules of the compression parameters based on the oedometer test results. It was discovered that the compression parameters increase linearly with the increase of salt content when the salt content is below the saturated salt content but remain constant once the saturated salt content is exceeded; in contrast, swelling parameters are independent of salt content. A three-dimensional (3D) compression model was developed based on the elastoplastic model by introducing the concept of osmotic suction (π) for salt content below the saturated salt content. The experimental results obtained from samples with 0.0%, 2.0%, and 4.0% salt contents were used to determine the parameters of the fitted equations, while those with 0.5%, 1.0%, and 1.5% salt contents were utilized to validate the model. The fitted curves of the 3D compression model exhibited good concordance with the experimental results, demonstrating the correctness and effectiveness of the proposed model.

In this study, the pressure-cast-in-situ pile with spray-expanded frustum (PPSF) was proposed to increase pile bearing capacity, reduce pile settlement, and improve construction speed. The construction process of the PPSF composed of pile body, ribbed plate, and expanded body with double frustum was introduced. To capture the PPSF response, field static load tests on three PPSFs installed with string wire stress gauges were carried out. The ultimate bearing capacity (UBC) of a single PPSF was obtained, and the distribution of axial force, skin friction, and end force were analyzed using the measured results. Following the assumption that the strength of pile–soil interface elements was statistically described by the probability density function of the Rayleigh distribution, the load transfer models of PPSF were established based on the disturbed state concept (DSC) theory. The research results showed that there is a compression effect between the expanded body of the PPSF and the surrounding soil, which can effectively improve the bearing capacity of the PPSF. Considering the concrete consumption per unit volume, the UBC of PPSF is 66% more than that of the cast-in-situ bored pile. According to the results of measured and fitted relationships, the load transfer models of PPSF can be well described using the DSC theory and the Rayleigh distribution.

Determining the uplift pressure at key points including the junctions of the floor and the cutoff wall beneath hydraulic structures and estimating the uplift force in these structures are vital issues in water engineering projects. The purpose of this study is to present a series of explicit and highly accurate formulas for determining these quantities for three different cutoff wall locations (at the upstream end, at intermediate locations, and the downstream end). In practice, the materials related to some types of cutoff walls may not be completely rigid due to their low permeability. In this study, the impact of permeability is incorporated into the analysis, and this is the novelty of this study. In order to include the effect of permeability, the capabilities of the SEEPW2D-numerical model that utilizes the FEM to solve the governing equations are used. After generating data sets, nonlinear regression equations are developed in order to estimate the uplift pressure at key points and the uplift force exerted on the hydraulic structures. To validate the results of the FEM, Khosla’s approach is used. Khosla’s solution is usable only for rigid cutoff walls, while proposed equations can be used for both impervious and pervious cutoff walls as an initial estimate in designs. Also, the results indicate that the decrease in the permeability of the cutoff wall is proportional to the value of the uplift pressure at the key points after the cutoff wall. This reduction is inversely related to the value of the uplift pressure at the key points before the cutoff wall. Accordingly, material that constitutes the cutoff wall has a great effect on seepage characteristics, and it is necessary to consider this in the analysis. Therefore, the permeability of the cutoff wall in any design should be selected depending on the case-specific conditions related to seepage and the stability of the structure.