Equivalent Hydraulic Conductivity Research Articles

Coupling stress and transmissivity to define equivalent directional hydraulic conductivity of fractured rocks

A DFN (Discrete Fracture Network) modelling approach is developed to couple stresses with fracture transmissivities and to evaluate large scale rock mass hydraulic conductivity. The transmissivity-stress coupling relies on a negative exponential correlation between normal stress acting on a fracture and fracture transmissivity, bounded by residual and maximal apertures. The remote stresses and the local stress fluctuations induced by the fractures themselves are combined in a semi-analytical approach to compute the normal stress acting on each fracture of a DFN. Directional equivalent hydraulic conductivities are numerically computed in all directions from a spherical permeameter setup. The resulting properties are first a cloud of points, where each point defines a direction and an equivalent hydraulic conductivity. The distribution of equivalent hydraulic conductivities is analyzed to define mean values, preferential directions and anisotropy ratio. The entire workflow is developed in the numerical platform DFN.lab. The capacity of the method to investigate the impact of the in-situ stresses on the rock mass hydraulic conductivity is illustrated for fracturing and in-situ stress conditions similar to the conditions at the Forsmark site in Sweden. We find that the stress fluctuations induced by the fractures have a significant impact on the resulting hydraulic conductivity field. They limit the anisotropy ratio to values close to a factor of 3 while the transmissivity distribution is correlated to orientations and spans several orders of magnitude. Sensitivity analyses, performed by changing the parameters of the transmissivity-stress law, show quantitatively how the directional hydraulic conductivities are rather controlled by the orientations of the in-situ stresses or by the underlying connectivity structure of the DFN.

On quantification of equivalent permeability tensor in sparsely fractured rock masses

The work presented in this paper is focused on the assessment of hydraulic conductivity in sparsely fractured rocks. Different simplified methodologies are used, including Oda's notion of permeability tensor as well as pipe network models, and the results are compared with those generated by a more accurate approach, which incorporates a constitutive law with embedded discontinuity (CLED). Several numerical examples involving fluid flow in the presence of discrete fracture networks are provided, and the estimates of principal values as well as eigenvectors of the equivalent conductivity tensor are compared for all methodologies employed. It is demonstrated that the predictions corresponding to pipe-network model, enhanced by the graph theory algorithm, are fairly consistent with CLED approach, particularly in terms of assessing the orientation of principal directions of permeability. A simple pragmatic procedure is therefore suggested for defining the anisotropic equivalent hydraulic conductivity operator.

Numerical estimation of the equivalent hydraulic conductivity for canal concrete lining with cracks

The equivalent saturated hydraulic conductivity of concrete lining (Ksce) is a key parameter to estimate seepage loss, while few studies have quantified the effect of cracks on Ksce, potentially leading to significant errors in canal seepage estimation. A three-dimensional numerical model is employed to simulate seepage loss from canals lined with concrete, and then to obtain the value of Ksce by an equivalent method. A total of 58,400 scenarios are simulated for different concrete lining and crack conditions (e.g., crack length, crack width, crack location, hydraulic conductivity of concrete (Ksc), and underlying soil (Ksoil)), and the corresponding Ksce values are estimated. Results show that the Ksce value determined by the equivalent method is reliable in calculating seepage loss from concrete lined canals. Ksce increases linearly with crack length with a slope Ck, and Ck exhibits a power function relationship with crack width, reaching a maximum value when the crack width surpasses the critical threshold, which ranges from 0.424 to 0.435 mm. When the crack width follows a log-normal distribution, the logarithmic value of Ck increases linearly with the mean value of the logarithmic crack width. The influence of crack location and Ksc on Ksce can be negligible. The maximum increment of Ksce of a crack is proportional to Ksoil. Considering the variation of Ksce with crack parameters and Ksoil, equations to determine the value of Ksce are established by adding the increment of Ksce caused by cracks to Ksc. This study establishes a quantitative relationship between Ksce and crack parameters, thereby enhancing the accuracy of seepage loss calculations in lined canal under different damage status.

Numerical assessment of equivalent hydraulic conductivity and electro-osmotic conductivity for electro-osmotic consolidation under two-dimensional plane-strain analysis

Numerical assessment of equivalent hydraulic conductivity and electro-osmotic conductivity for electro-osmotic consolidation under two-dimensional plane-strain analysis

A modified Green-Ampt infiltration model for muddy water

The Green-Ampt infiltration model has been widely used because of its simple structure and clear physical meaning of the parameters. The model parameters were improved using the equivalent saturated hydraulic conductivity to develop the Green-Ampt infiltration model for muddy water (MWGA). A saturated soil column infiltration test with muddy water was conducted to determine the influence of the soil texture (sandy soil and silt loam) and the sand content (S = 3 %, 6 %, 9 %, and 12 %) on the hydraulic conductivity of saturated soil columns. The equivalent saturated hydraulic conductivity was derived based on several assumptions and under different conditions. Eight one-dimensional vertical infiltration tests were conducted under the same conditions for verification. The MWGA was simplified according to the results, and four tests with different sand contents (S = 4 % and 10 %) were conducted to validate the MWGA for both soils (the simplified infiltration model was used for the sandy soil). The results indicated that the hydraulic conductivity trend of the saturated soil column during the infiltration of muddy water into sandy soil was in accordance with the physical model. The hydraulic conductivity of the silt loam was only influenced by the sand content and showed a significant linear relationship with the sand content. The root mean square error (SRMSE) obtained from the validation test under the same conditions was close to 0, and the absolute value of the relative error (SRE) was less than 15 %, indicating a good fit. The results of the validation tests for different sand contents showed that the simulated and observed values were close to the 1:1 line, demonstrating high model accuracy. Our results provide new insights into the infiltration of muddy water and the mechanism of reducing the infiltration rate due to the dense layer formed on the soil surface.

A Dimension-Reduced Line-Element Method to Model Unsaturated Seepage Flow in Porous Media

Contrary to the continuum hypothesis, which averages water flow across the entire domain, including both grains and pores, the line-element model concentrates unsaturated flow in the pore space in the intermediate region of horizontal and vertical channels. The flux equivalent principle is used to deduce the equivalent unsaturated hydraulic conductivity, the flow velocity and the continuity equations. It is found that the relative hydraulic conductivities derived from the line-element model and the continuum model are identical. The continuity equations in the two models are also similar, except that the coefficient in the water content term is half that in the line-element model. Thus, the unsaturated flow problem in porous media is transformed into a one-dimensional problem. A dimension-reduced finite line-element method is proposed that includes a complementary algorithm for Signorini’s-type boundary conditions involving the seepage-face boundary and the infiltration boundary. The validity of the proposed model is then proved by good agreement with analytical, experimental and simulated results for one-dimensional infiltration in a vertical soil column, unsaturated flow in a sand flume with drainage tunnels, and transient unsaturated flow water-table recharge in a soil slab, respectively. In general, the proposed method has good computational efficiency, especially for smaller mesh sizes and short time intervals.

Equivalent Hydraulic Conductivity of Heterogeneous Aquifers Estimated by Multi-Frequency Oscillatory Pumping

Aquifers are a vital part of our water cycle and modeling groundwater flow is paramount for a number of environmental applications. Modeling requires the estimation of aquifer properties, which is mostly achieved by field pumping tests. Oscillatory pumping tests involve repeated pumping and injection of aquifer water, which generates a periodic head signal. We investigate the estimation of equivalent hydraulic conductivity (Keq) in an oscillatory pumping test with a multi-frequency excitation. Synthetic head data are generated from numerical simulations of pumping in heterogeneous aquifers and an inverse method is applied to estimate Keq. The method involves a Fast Fourier Transform (FFT) analysis for obtaining the spatial distribution of head amplitude and then matching the amplitudes using a semi-analytical solution of a homogeneous aquifer with conductivity Keq. We investigate the dependence of Keq on pumping frequency in view of the previous literature, which has found increasing values for higher frequencies. We did not find this increase in Keq with frequency and minor variations which were observed appear to be a result of numerical error. The result implies that oscillatory pumping field tests can be used for Keq estimation without any corrections for frequency dependence.

An equivalent line element approach for free surface flow through two-dimensional rock mass including fracture networks

In this paper, an equivalent line element method is established to analyze seepage problems with free surface through two-dimensional rock mass, including fracture networks. Low-permeablity rock matrix is characterized by the line elements as well as the high-permeablity fracture networks. Unlike the conventional equivalent continuum model, water flow in a rock mass is restricted to the line elements, and the equivalent hydraulic conductivity is determined according to Darcy's law and flux equivalence principle. As a result, uniform expressions of governing equations and boundary conditions are formulated, and the corresponding numerical procedure is developed by introducing the local coordinate and continuous Heaviside function. Satisfactory agreements with the existing test and numerical data verify this proposed line element method. The numerical solutions on the fractured slope indicate that the geological features of fractures have a substantial effect on locating the free surface. In addition, the proposed line element method can efficiently achieve accurate results with less computing time, iteration, and storage.

Coupled hydromechanical analysis of sparsely fractured crystalline rocks

This paper addresses the issue of evolution and coalescence of localized damage zones in sparsely fractured crystalline rocks. The approach incorporates a constitutive law with embedded discontinuity, which is phrased in terms of both the hydraulic and mechanical response. The formulation takes into account the hydromechanical interaction in regions intercepted by discontinuities. An internal length scale parameter is employed in the definition of equivalent hydraulic conductivity and the tangential stiffness operators, and the onset of newly developed macrocracks is detected by the bifurcation analysis. An enhanced mixed u-p finite element formulation is derived which considers the effect of progressive evolution of the fracture aperture in the weak statements of balance equations. Fully implicit temporal discretization is employed, and the finite element formulation is stabilized by invoking the Polynomial-Pressure-Projection (PPP) technique. A coupled FE analysis is conducted examining the response of Luc du Bonnet granite, with pre-existing fracture network, subjected to plane strain compression that triggers the crack propagation and coalescence. The approach is first verified on some benchmark problems that involve the presence of a dominant fracture. The results of simulations are compared with those obtained using a very fine mesh incorporating interface elements. Later, a series of coupled analyses are carried out examining the hydromechanical response in the presence of multiple fractures.

Hydraulic conductivity assessment of falling head percolation tests used for the design of on-site wastewater treatment systems

The suitability of a location for an on-site wastewater treatment process (for areas which lack access to centralised wastewater treatment systems) requires an assessment of the permeability of the soil into which the effluent will be discharged. In many jurisdictions this is determined using some type of in-situ percolation test. Falling head percolation tests, which give a value of percolation time (PT) that is empirically related to the notion of hydraulic conductivity, are widely used as they are relatively simple to carry out, but the test does not have a sound theoretical framework and test methods are not standardised internationally. In comparison, the saturated hydraulic conductivity of a soil obtained from a constant head well permeameter test is independent of test conditions, and so is a more suitable metric for design. A database of over 900 falling head tests carried out across a range of different subsoil types in Ireland has been collated, all with the inherent limitations of the existing regulative framework regarding the percolation test and soil texture assessment. These tests were then modelled using Hydrus 2-D numerical modelling simulations to determine equivalent field saturated hydraulic conductivity (Kfs) values and thereby provide a correlation with PT values across the range of subsoil conditions. In addition, falling head tests have been carried out in parallel to constant head permeameter tests in the field and compared against the relationship derived from the broad dataset of simulated results. This revealed an optimal solution by which to determine Kfs from the field permeameter test (using parameters recommended for most structured soils from clays to loams). The trendline based on Irish data was also compared against more generic formulations of the relationship between PT, and Kfs and shown to match closely, particularly the Reynolds (2016) ‘unified’ methodology. Finally, the Irish threshold PT limits for on-site wastewater treatment have been converted to Kfs values and compared against other international standards.

Sets of infiltration models for water infiltration in sustainable urban drainage systems

Infiltration is a crucial process in various fields such as hydrology, agriculture, urban soils, and particularly for Sustainable Urban Drainage Systems (SUDS) operation. Over the past century, the physics of infiltration has been extensively studied by developing models that estimate the dynamics of infiltration. In this study, three physically-based infiltration models (CH1, CH2, and CH3) have been developed as part of the Canoe Hydrobox (CH) platform, designed to simulate and evaluate the performance of SUDS. The three models rely on similar approaches to the Green-Ampt (GA) model by describing the water flux as the product of the equivalent hydraulic gradient and the equivalent hydraulic conductivity. The models differ in their ways of defining the hydraulic gradient and conductivity from the hydric conditions, soil parameters, and geometric features. The two first models (CH1 and CH2) consider an increase in the hydraulic conductivity with infiltrated water amount, whereas the last model (CH3) considers only the saturated hydraulic conductivity. For the hydraulic gradient, the first model considers the difference between the surface water pressure head and the height of infiltrated water. The other two models consider the difference between the surface water pressure head and the isostatic water pressure head at the surface in equilibrium with the height of infiltrated water. These models were applied to simulate water infiltration processes into dry, wet, and intermediate-wet soils. We compared these results with the numerical solution of the Richards equation using HYDRUS software. The comparison allowed the assessment of the capability of CH models to satisfy the critical principles of soil water infiltration. Subsequently we used the three models to invert six real experimental infiltration data to test their capability to work in inverse mode. The two models (CH1 and CH2) produced specific time-evolution of infiltration rates in disagreement with the physics of water infiltration under regular conditions (e.g., no water repellence). The third model (CH3) performed the best for both direct and indirect modes and is therefore considered as the best candidate. The CH3 model will be implemented in the new version of Canoe Hydrobox (CH) platform. This study provides a basis for further research into hydrological models for SUDS and their hydraulic performance.

Estimating the permeability of fractured rocks using topological characteristics of fracture network

The variability and inter-influence of individual geometric parameters make permeability evaluation of fractured rocks based on fracture geometric characteristics challenging. Therefore, three independent topological parameters, fracture mean density (εmean), network connectivity (nseg), and the average number of fractures intersecting with inlet and outlet boundaries per meter (Cmean) were proposed to describe the geometric characteristic of fractured rock, and a prediction model of permeability was established in terms of these topological parameters and fracture aperture. The relationship between topological parameters, aperture, and permeability was analyzed according to more than 300 models generated by the Monte Carlo method considering different fracture densities, lengths, and orientations. Fitting these results, a multivariate regression equation with a correlation coefficient larger than 0.91 was constructed for prediction permeability. We also found that nseg and e play a more important role in permeability when compared to εmean and Cmean. For fractured rocks of different topological sub-domains, a method physically simplifying them to a fracture of equivalent hydraulic conductivity is proposed, and then assembling them based on the mass conservation and compatible hydraulic pressure condition. The derivation between permeability obtained by prediction model and numerical simulation is less than 2%, verifying the prediction model.

Applicability of the Continuum Mapping Approach for Groundwater Flow Modeling in 3D Fracture Networks

Abstract A methodology for simulating groundwater flow in three-dimensional (3D) stochastic fracture rocks based on a commonly used finite-difference method is presented in this paper. Different realizations of fracture networks are generated by the fracture continuum method (FCM), in which appropriate 3D cuboids are used to describe the geometry of fractures. Then, the effects of different parameter distributions on the fracture networks indicated that the length, orientation, and density of fractures all play significant roles in the connectivity of fractures in this methodology. Greater length and density and wider orientation range of fractures lead to greater connectivity. The proper contrast in hydraulic conductivities between the fractures and matrix is found to be approximately 105 due to the contribution of fluid flow in the matrix which can be ignored. It is shown that the fracture density plays a key role in stabilizing the equivalent hydraulic conductivity (Ke) of the fracture networks. Furthermore, the greater length and closer orientation of fractures to the general flow direction, the larger Ke of the generated fracture networks possess. The findings of this study can help for a better understanding of the mechanism of FCM and the influence of geometry characteristics on the hydraulic conductivity of FCM models.

Evaluating the effect of aquifer heterogeneity on multiobjective optimization of in-situ groundwater bioremediation

In-situ bioremediation is a cost-effective technique to eliminate petroleum hydrocarbons from groundwater. In previous studies, this has been mostly applied under the approximation of a homogeneous porous medium, even though in reality aquifers are often characterized by significant heterogeneities. Here, different heterogeneous and equivalent homogeneous hydraulic conductivity fields are considered to study the effect of aquifer heterogeneity on optimal in-situ bioremediation. For this, the multiobjective simulation-optimization (S/O) model referred to as BIOEFGM-NSGA II is proposed — which uses the element-free Galerkin method (EFGM) for discretization of the governing equations, and the non-dominated sorting genetic algorithm II (NSGA II) for multiobjective optimization. This model is then applied to different heterogeneous conductivity fields generated through a pseudo-random correlated field generator for different combinations of variance and correlation lengths with constant mean. Results show that the optimal pumping policy for an equivalent homogeneous conductivity field violates the constraint of maximum allowable concentration in all the studied heterogeneous fields. To satisfy this constraint, in-situ bioremediation cost increases by 8.47% to 56.83% to that of a homogeneous field. It shows the significance of aquifer heterogeneity in designing an optimized in-situ bioremediation system and hence, should be incorporated in the S/O model for in-situ groundwater bioremediation.

A Drain Spacing Tool That Estimates the Optimum Subsurface Drain Spacing for Maximum Profit

Highlights An empirical equation was embedded in a user-friendly tool to estimate the site-specific design drainage rate. The site-specific design drainage rate was based on the local soil, weather, and economics of the area of interest. The tool uses the site-specific design drainage rate to estimate the optimum drain spacing. The optimum drain spacing maximizes the economic return on investment. Abstract. Properly estimating the subsurface drain spacing is critical to optimizing crop production. The Hooghoudt equation can be used in humid climates to approximate the drain spacing. However, the application of this equation has been limited due to site-specific data requirements and because it is a complicated process that is not usually practical for practitioners. Traditionally, drainage contractors have chosen a drain spacing without using the Hooghoudt equation. The objective of this article is to develop a user-friendly decision-support tool that estimates the site-specific optimum drain spacing for maximum economic return on investment. We developed the Drain Spacing Tool for the Midwest USA based on the Hooghoudt equation and site-specific inputs. The tool automatically acquires the site-specific equivalent saturated hydraulic conductivity of the soil profile and depth to the restrictive layer from the gSSURGO database, and the user manually enters the desired drain depth. The site-specific input of design drainage rate (DDR), that is required in the Hooghoudt equation, is estimated from an empirical equation that was developed from a DRAINMOD modeling study. The site-specific inputs for the empirical equation include site-specific 30-year average growing-season rainfall, drain depth, equivalent saturated hydraulic conductivity, and depth to the restrictive layer, all of which are automatically acquired from gSSURGO, except for the rainfall data, which was acquired from the PRISM Climate Group. The site-specific DDR value from the empirical equation was then used in the Hooghoudt equation to estimate the optimum drain spacing that maximizes economic return on investment. In conclusion, the tool estimates the site-specific optimum drain spacing based on the local soil, weather, and economics of the area of interest. Keywords: Decision-support tool, Design drainage rate, DRAINMOD, Farm profitability, Tile drainage.

Statistical Analysis of Aquifer Hydraulic Properties by a Continuous Pumping Tomography Test: Application to the Boise Hydrogeophysical Research Site

AbstractCharacterizing aquifer heterogeneity is paramount for accurate flow and transport modeling. In this work, we present a new approach for statistical analysis of hydraulic properties in continuous pumping tomography tests of a phreatic aquifer. The method entails determining equivalent hydraulic conductivity (Keq), specific storage (Ss,eq), and specific yield (Sy,eq) at many locations in the field and then calculating statistical moments of the equivalent properties, assuming they are random space variables. Equivalent properties are defined as the ones pertinent to a homogeneous aquifer for which the head time dependent signal fits the one observed in the pumping test. Calculation is carried out in a novel approach, by matching measured head data to two separate semianalytical solutions considering two time periods, early and late. We apply this approach to the Boise Hydrogeophysical Research Site and find that the equivalent property spatial averages decrease with horizontal distance from the pumping well and appear to stabilize at sufficiently large distances, in line with existing theory for Keq. The squared coefficient of variation shows similar behavior, with values indicating a weakly heterogeneous aquifer. Furthermore, estimated values for Keq, Ss,eq, and Sy,eq are in agreement with literature values for the site.

Seepage-Fractal Characteristics of Fractured Media Rock Materials Due to High-Velocity Non-Darcy Flow

Under the influence of internal and external factors, a fracture network is easily generated in concrete and rock, which seriously endangers project safety. Fractal theory can be used to describe the formation and development of the fracture network and characterize its structure. Based on the flow balance in the node balance field, Forchheimer’s law is introduced to derive the control equation of high-velocity non-Darcy flow in the fracture network. The fracture network is established according to the geological parameters of Sellafield, Cumbria, England. A total of 120 internal fracture networks are intercepted according to 10 dimensions (1 m, 2 m, …, 10 m) and 12 directions (0°, 30°, …, 330°). The fractal dimension, equivalent hydraulic conductivity (K), and equivalent non-Darcy coefficient (β) of the fracture network are calculated, and the influence of the fractal dimension on K and β is studied. The results indicate that the fractal dimension of the fracture network has a size effect; with the increase in the size, the fractal dimension of the fracture network undergoes three stages: rapid increase, slow increase, and stabilization. In the rapid increase stage, K and β do not exist. In the slow increase stage, K exists and is stable, and β does not exist. In the stabilization stage, K and β both exist and are stable. The principal axes of the fitted seepage ellipses of K and β are orthogonal, and the main influencing factors are the direction and continuity of the fracture.

Groundwater responses to recharge and flood in riparian zones of layered aquifers: An analytical model

A riparian zone is an important element in a river-aquifer system, controlling water exchange and other chemical and biological processes between a river and an aquifer. Complex groundwater flow patterns may occur due to aquifer heterogeneity within a riparian zone. The purpose of this study is to investigate the impacts of layered heterogeneity on water exchange in the riparian zone using a mathematical model for groundwater flow in a two-layer aquifer that is recharged by precipitation and floods. A semi-analytical solution is derived for the hydraulic head, lateral discharge, and fluxes between the layers. Results demonstrate that the hydraulic conductivity difference between the two layers enhances lateral flow in the higher permeable layer and, more importantly, generates vertical flow between the two layers. The vertical flow induced by the recharge event is downward while it could be upward or downward induced by the flood event, which is determined by the contrast in permeabilities of the two layers. Using an equivalent hydraulic conductivity approach underestimates discharge of the two-layer aquifer due to recharge or flood. The analytical solution closely matched the observed hydraulic heads in riparian zone well of White Clay Creek and provided reasonable estimates of aquifer parameters. The present solution provides a valuable basis for further study of chemical and biological processes in riparian zone.

Effects of freeze–thaw cycles on the properties of polyethylene geomembranes

High-density polyethylene (HDPE) geomembranes (GMs) are frequently used as fluid barrier components of cover systems for mine site reclamation in regions that are prone to freeze–thaw cycles (FTCs). However, HDPE GMs are more susceptible to stress cracking than linear low-density polyethylene (LLDPE) GMs. Hence, LLDPE GMs are increasingly considered as alternatives to HDPE GMs in cover systems. Nevertheless, little information is available on LLDPE compared to HDPE GMs. Moreover, little is known about the changes in the fluid barrier properties (the equivalent hydraulic conductivity and the oxygen sorption and diffusion coefficients) for these two materials with FTCs. The purpose of this study is therefore to compare the effects of FTCs on the tensile, hydraulic, and oxygen sorption and diffusion properties of HDPE and LLDPE GMs. To do so, GM sheets were subjected up to 300 FTCs. Mechanically, both GMs got stiffer and their tensile break properties increased with increasing number of FTCs. However, although the GM fluid barrier properties changed with FTCs, the equivalent hydraulic conductivity and the oxygen permeation coefficient remained within an order of magnitude of 10−14 m/s and 10−13 m2/s, respectively. Up to 300 FTCs would therefore have no adverse effects on HDPE and LLDPE GMs.

Seawater intrusion into an underground water-sealed oil storage cavern: Effects of water curtain system, hydraulic conductivity and dispersivity

The construction of underground facilities in coastal area usually results in seawater intrusion, which affects the service life of underground facilities. Considering the effects of different water curtain systems, hydraulic conductivity, and dispersivity, the dynamic seawater intrusion characteristics of an underground water-sealed oil storage cavern in coastal area have been obtained by numerical simulation based on multi-physical field coupling theory. The results show that in terms of the extent and scope of seawater intrusion, compared with only setting horizontal water curtain, adding vertical water curtain is more effective in controlling seawater intrusion; as the depth of the vertical water curtain increases, the effect of preventing seawater intrusion is better. When the equivalent hydraulic conductivity is the same and the anisotropy ratio of hydraulic conductivity increases, the extent of seawater intrusion is weaker; when the anisotropy ratio of hydraulic conductivity is the same and the equivalent hydraulic conductivity increases, the extent of seawater intrusion is weaker. As the longitudinal dispersivity becomes larger, the extent of seawater intrusion is weaker. The water-sealed safety and water inflow of the underground water-sealed oil storage cavern have been analyzed. The research results could provide a theoretical basis for the seawater intrusion problem faced by the construction of underground water-sealed oil storage caverns in coastal area, and have a certain guiding effect on the excavation of underground facilities in coastal area.