Differential pressure response simulation method and system for interface of strongly hydrated confined layered minerals

Abstract

The application discloses a differential pressure response simulation method and system for a strong hydration limited layered mineral interface and belongs to the technical field of limited hydration structure analysis. The differential pressure response simulation method for the strong hydration limited layered mineral interface comprises the following steps: a strong hydration limited solid-liquid-solid interface system is constructed and pretreated to obtain an initial stable interface structure; the interface piston layer and the fixed skeleton layer are identified according to the spatial distribution of the mineral sheet layer in the normal direction; a local equivalent pressure background between layers is established based on the initial stable interface structure, an engineering disturbance pressure is introduced, and a differential pressure response system is constructed; a local normal additional force is applied to the interface piston layer to realize local interface normal loading and perform stability control; layer structure response parameters are extracted for analysis; and a two-way convergence verification is performed to confirm that the equilibrium state is a true stable equilibrium state. The application can truly reflect the local stress state of the strong hydration limited interface, and avoids the non-physical compression and numerical instability problems caused by traditional overall NPT loading.

Description

Technical Field

[0001] This invention belongs to the field of confined hydration structure analysis technology, specifically relating to a differential pressure response simulation method and system for strongly hydrated confined layered mineral interfaces. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Layered clay minerals, due to their interlayer exchangeable ions, high specific surface area, and significant interfacial hydration characteristics, are widely used in shield tunneling mud, drilling fluids, seepage prevention materials, nuclear waste containment, and deep-earth engineering. Under conditions of deep water high head, mud compaction, and particle contact, typical layered minerals such as montmorillonite typically form nanoscale, strongly hydrated confined solid-liquid-solid interfaces between particles. The confined water structure, ion distribution, and interfacial interactions within these interfaces directly affect interlayer compaction, hydration response, interfacial stability, and particle reorganization behavior.

[0004] Existing research on the interlayer stress and interface response of layered minerals has the following main shortcomings: Firstly, traditional studies on interlayer hydration and expansion mainly analyze the structural change patterns by changing conditions such as water content and interlayer ion composition. However, the research focuses on the structural differences in open systems or conventional hydration processes, which makes it difficult to truly reflect the stress state and dynamic response characteristics of local interfaces under engineering compaction conditions.

[0005] Secondly, molecular dynamics-based pressure loading simulations typically employ a global non-potential pressure (NPT) loading method, directly applying external pressure to the entire simulation system and achieving the compression process through overall box compression. However, in reality, the interlayer interface of a strongly hydrated confined space already possesses local equivalent pressure formed by the coupling of factors such as confined hydration repulsion, electric bilayer interaction, ion layer confinement, and force transmission from the particle framework, which is inconsistent with the macroscopic external pressure. Traditional global NPT loading easily leads to problems such as overall box compression rather than local interface response, and the solid framework bearing unrealistic pressure transmission. Furthermore, under strongly confined high-pressure conditions, the rapid release of local potential energy can easily cause numerical problems such as temperature instability, PPPM collapse, and atom loss.

[0006] Furthermore, existing technologies lack a progressive stabilization loading mechanism and path consistency verification method for strongly hydrated confined closed interlayer systems, making it difficult to effectively distinguish between real equilibrium structures and local metastable structures. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a differential pressure response simulation method and system for strongly hydrated confined layered mineral interfaces.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the technical solution of the present invention provides a differential pressure response simulation method for strongly hydrated confined layered mineral interfaces, including: A strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, a confined fluid layer, and opposing layered mineral sheets was constructed and pretreated to obtain an initial stable interface structure. Identify the interface piston layer and the fixed skeleton layer based on the spatial distribution of layered minerals in the normal direction; Based on the initial stable interface structure, a local equivalent pressure background is established between layers. Based on the local equivalent pressure background, engineering disturbance pressure is introduced to construct a differential pressure response system. Based on the differential pressure response system, under the condition of fixed simulation box normal dimensions, a local normal additional force is applied to the interface piston layer to achieve local interface normal loading. Molecular dynamics simulations were performed on a strongly hydrated confined solid-liquid-solid interface system. The system stabilization was controlled during local interface normal loading, and the simulation effectiveness was judged based on stability criteria to obtain equilibrium trajectory data. Interlayer structural response parameters are extracted based on equilibrium trajectory data, and the interlayer structure, hydration behavior, and local compaction response are analyzed using a two-way convergence verification method.

[0009] In at least one embodiment, a strongly hydrated confined solid-liquid-solid interface system is constructed, specifically including: based on the crystallographic parameters of the target layered mineral, constructing a silicate mineral sheet model with a 2:1 type layered structure, introducing permanent layer charges according to the isomorphic substitution rule, and adding interlayer compensation cations to form the target layered mineral sheet model. Based on the target layered mineral sheet model, a supercell model of the layered mineral sheet is constructed, and a preset number of water molecules and compensating ions are added to the interlayer region to assemble a strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, confined water layers, and layered mineral sheets.

[0010] In at least one embodiment, the interface piston layer is a mineral surface atomic region located above the interlayer fluid region and close to the confined interface, used to receive external normal additional force and transmit pressure to the confined interface; the fixed skeleton layer is a deep mineral region located below the interlayer fluid region and far from the interface, used to maintain the overall mineral skeleton stability; the mineral surface atomic region located below the interlayer fluid region and close to the confined interface is the lower interface support response layer, which participates in the interlayer force balance as a local support response interface, rather than as an independent additional load object.

[0011] In at least one embodiment, an interlayer local equivalent pressure background is established based on the initial stable interface structure. Specifically, based on the interlayer confined water structure, electric double layer effect, van der Waals attraction, ion layer confinement, and particle skeleton force transmission of the initial stable interface structure of the strongly hydrated confined solid-liquid-solid interface system, an interlayer local equivalent pressure background is established to characterize the local high-constraint normal pressure state formed by confined hydration repulsion, electric double layer effect, ion layer confinement, and particle skeleton force transmission in the strongly hydrated confined interface. The local interface pressure constraint intensity is not equivalent to the macroscopic engineering pressure level.

[0012] In at least one embodiment, normal loading is applied to the local interface, specifically including: based on the constructed differential pressure response system, while keeping the normal dimensions of the simulation box fixed, the total normal additional force applied to the interface piston layer is determined according to the correspondence between the target engineering disturbance pressure and the interface force area, and the normal additional force is distributed to the atomic regions of the interface piston layer to achieve local pressure transmission at the interface.

[0013] In at least one embodiment, the system is stabilized by one or more of the following: applying independent dynamic control to the interlayer fluid region and the interface response region, applying fixed constraints to the deep mineral framework far from the interface, applying constraints to the bond lengths and bond angles of water molecules, periodically removing the overall linear momentum and angular momentum of the system, and applying local dynamic stabilization control to the locally high-response region of the interface.

[0014] In at least one embodiment, the stability criteria include one or more of the following: the system potential energy changes continuously without abnormal drops; the effective free space evolution process between layers is continuous without instantaneous jumps; the system temperature fluctuations remain stable without persistent temperature spikes; the configuration snapshot during the simulation does not show atomic scattering, layer crossing, or local structural collapse; there are no errors in atomic loss or bond loss; and there is no PPPM calculation crash while long-range electrostatic calculations remain stable and convergent.

[0015] In at least one embodiment, the interlayer structure response parameters include one or more of the following: interlayer effective free space parameters, z-axis density distribution of water molecules and ions, radial distribution function, coordination number, mean square displacement, diffusion coefficient, and interfacial energy change.

[0016] In at least one embodiment, the bidirectional convergence verification method specifically includes: performing interlayer evolution simulations starting from the initial small spacing and the initial large spacing respectively, wherein the small spacing system is used to observe the interlayer expansion process, and the large spacing system is used to observe the interlayer compaction and contraction process; if different evolution paths eventually converge to similar interlayer structures, it is determined that the current interlayer structure has reached a stable equilibrium state.

[0017] Secondly, the technical solution of the present invention also provides a differential pressure response simulation system for strongly hydrated confined layered mineral interfaces, comprising: The system construction module is configured to: construct a strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, a confined fluid layer, and relatively arranged layered mineral sheets, and perform preprocessing to obtain an initial stable interface structure; The interface recognition module is configured to identify the interface piston layer and the fixed skeleton layer based on the spatial distribution of layered minerals in the normal direction. The pressure response module is configured to: establish an interlayer local equivalent pressure background based on the initial stable interface structure, introduce engineering disturbance pressure on the basis of the local equivalent pressure background, and construct a differential pressure response system. The local normal loading module is configured to apply a local normal additional force to the interface piston layer based on the differential pressure response system, under the condition of fixed simulation box normal size, to achieve local interface normal loading. The system simulation module is configured to: perform molecular dynamics simulations on strongly hydrated confined solid-liquid-solid interface systems, control system stabilization during local interface normal loading, determine the effectiveness of the simulation based on stability criteria, and obtain equilibrium trajectory data; The analysis output and verification module is configured to: extract interlayer structural response parameters based on equilibrium trajectory data, and analyze the interlayer structure, hydration behavior and local compaction response by combining a two-way convergence verification method.

[0018] The beneficial effects of the above-described technical solution of the present invention are as follows: The differential pressure response simulation method for strongly hydrated confined layered mineral interfaces of this invention establishes a local equivalent pressure background for the strongly hydrated confined interface and introduces a differential pressure response. It treats engineering disturbance pressure as a differential disturbance superimposed on the inherent pressure background rather than the absolute pressure of the system, thus overcoming the limitation of traditional overall NPT loading methods that ignore the existing pressure state within the interface. This method can realistically reflect the local stress state of the confined interface. Simultaneously, by identifying the interface piston layer and the fixed skeleton layer, and applying a local normal additional force only to the piston layer under fixed simulation box normal dimensions, it avoids non-physical stress transfer caused by overall box compression and abnormal pressure bearing problems of the solid skeleton. Through a combined stabilization control strategy and a bidirectional convergence verification mechanism, it effectively suppresses the risk of numerical instability under high-pressure confinement conditions and can effectively distinguish between the real equilibrium structure and the local metastable structure. This achieves reliable simulation and characterization of the local compaction behavior, hydration structure evolution, and interface stability of strongly hydrated confined layered mineral interfaces.

[0019] The advantages of the present invention, as well as its additional advantages, will be described in detail in the following specific embodiments. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute a limitation thereof.

[0021] Figure 1 This is a flowchart of the differential pressure response simulation method for strongly hydrated confined layered mineral interfaces disclosed in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of a confined solid-liquid-solid interface model under strong hydration state disclosed in Embodiment 1 of the present invention; wherein, (a) is a three-dimensional structural model of the solid-liquid-solid interface, and (b) is a top view of the solid interface structure. Figure 3 This is a schematic diagram of the division between the interface piston layer and the fixed skeleton layer disclosed in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the differential pressure response system and local interface normal loading under a local equivalent pressure background disclosed in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of bidirectional path convergence verification disclosed in Embodiment 1 of the present invention; Figure 6 This refers to water molecules under different pressure conditions as disclosed in Example 1 of the present invention. The z-axis density distribution diagrams are shown; where (a) is the z-axis density distribution diagram of Clay O under different pressure conditions, and (b) is the z-axis density distribution diagram of Clay O under different pressure conditions. The z-direction density distribution diagrams are shown in (c) and (d) respectively. (c) is the z-direction density distribution diagram of Water H under different pressure conditions. Figure 7 These are snapshot images of the interlayer structure configuration under different engineering disturbance pressure conditions disclosed in Embodiment 1 of the present invention; wherein, (a) is a snapshot image of the interlayer structure configuration under 0 atm, (b) is a snapshot image of the interlayer structure configuration under 10 atm, (c) is a snapshot image of the interlayer structure configuration under 50 atm, (d) is a snapshot image of the interlayer structure configuration under 100 atm, (e) is a snapshot image of the interlayer structure configuration under 500 atm, (f) is a snapshot image of the interlayer structure configuration under 1000 atm, and (g) is a snapshot image of the interlayer structure configuration under 5000 atm. Figure 8 This is a graph showing the results of effective free space parameters between layers under different engineering disturbance pressure conditions as disclosed in Embodiment 1 of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. It should be noted that, without conflict, the various embodiments and features within those embodiments can be combined with each other. The embodiments will now be described in detail with reference to the accompanying drawings.

[0025] Example 1 As introduced in the background section, existing research on the interlayer stress and interface response of layered minerals mainly follows two technical approaches. First, traditional studies on interlayer hydration and expansion primarily analyze the changes in interlayer structure, hydration layers, and interface interactions under different system parameters by altering conditions such as water content, interlayer ionic composition, layer charge distribution, and hydration state. Some studies further combine spring constraints and free energy calculations to analyze interlayer expansion pressure or structural stability. While these methods can reveal the hydration behavior and interlayer structural changes of layered minerals, their research focus is mainly on structural differences in open systems or conventional hydration processes, rather than on the dynamic pressure response process, local compaction behavior, and stable loading paths of strongly hydrated confined interfaces under different pressure conditions. Therefore, they cannot accurately reflect the stress state and structural response characteristics of local interfaces under engineering compaction conditions.

[0026] Secondly, pressure loading simulations based on molecular dynamics typically employ a global NPT loading method, directly applying external pressure to the entire simulation system and achieving the compression process through overall box compression. However, the actual pressure state at the interface of a strongly hydrated confined layer originates not only from macroscopic engineering pressure but is also coupled with factors such as local particle contact constraints, confined hydration repulsion, electric bilayer interactions, ion layer interface interactions, and force transmission from the particle framework. Therefore, the equivalent pressure at the local interface does not correspond to the macroscopic external pressure. Traditional global NPT loading methods, by directly mapping macroscopic pressure to the entire simulation system, are prone to problems such as overall box compression rather than local interface response, the solid framework bearing unrealistic pressure transmission, and instantaneous decompression or abnormal compaction of the interlayer structure. Furthermore, under strongly confined high-pressure conditions, rapid release of local potential energy can easily lead to numerical problems such as temperature instability, long-range electrostatic convergence anomalies, PPM calculation crashes, and missing atoms, making it difficult to achieve stable pressure loading and reliable response analysis at strongly hydrated confined interfaces.

[0027] Furthermore, existing technologies typically lack progressive stabilization loading mechanisms, path consistency verification methods, and dynamic stability criteria for strongly hydrated confined closed interlayer systems, making it difficult to effectively distinguish between real interface equilibrium structures and local metastable structures. This results in insufficient reliability and comparability of interface structure response results under different pressure conditions.

[0028] To overcome the shortcomings of the prior art, in a typical embodiment of the present invention, such as... Figures 1 to 8 As shown, this embodiment discloses a differential pressure response simulation method for a strongly hydrated confined layered mineral interface. By establishing a local equivalent pressure background, a differential pressure response method, and a local interface normal loading method under fixed box size conditions, supplemented by bidirectional convergence verification, a stable response simulation of the interlayer structure and hydration behavior under engineering disturbance pressure conditions is achieved. The differential pressure response simulation method for a strongly hydrated confined layered mineral interface specifically includes the following steps: S1. Construct a strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, a confined fluid layer, and opposing layered mineral sheets, and perform pretreatment to obtain an initial stable interface structure; S2. Identify the interface piston layer and the fixed skeleton layer based on the spatial distribution of layered minerals in the normal direction; S3. Based on the initial stable interface structure, establish the interlayer local equivalent pressure background, and introduce engineering disturbance pressure on the basis of the local equivalent pressure background to construct a differential pressure response system; S4. Based on the differential pressure response system, under the condition of fixed simulation box normal dimensions, a local normal additional force is applied to the interface piston layer to realize local interface normal loading; S5. Molecular dynamics simulations were performed on strongly hydrated confined solid-liquid-solid interface systems. The system stabilization was controlled during local interface normal loading, and the simulation effectiveness was judged based on stability criteria to obtain equilibrium trajectory data. S6. Based on equilibrium trajectory data, interlayer structural response parameters are extracted, and combined with a two-way convergence verification method, the interlayer structure, hydration behavior, and local compaction response are analyzed.

[0029] The differential pressure response simulation method for the strongly hydrated confined layered mineral interface described above will be explained in detail below with reference to specific implementation methods.

[0030] S1. Construct a strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, a confined fluid layer, and opposing layered mineral sheets, and perform pretreatment to obtain an initial stable interface structure.

[0031] In this step, the strongly hydrated confined interface refers to a solid-liquid-solid confined interface formed by relatively parallel layered mineral sheets and the nanoscale water-bearing regions between them, and continuously affected by the hydration of the mineral surface.

[0032] Specifically, when constructing a strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, a confined fluid layer, and opposing layered mineral sheets, a silicate mineral sheet model with a 2:1 layered structure is first constructed based on the crystallographic parameters of the target layered mineral. Permanent layer charges are then introduced according to the isomorphous substitution rule, and interlayer compensating cations are added to form the target layered mineral sheet model. The layered minerals include one or more of montmorillonite, vermiculite, illite, chlorite, or mixed-layer clay minerals.

[0033] Based on this, using the target layered mineral sheet model, a supercell model of the layered mineral sheets was constructed using molecular dynamics simulation software. A predetermined number of water molecules and compensating ions were added to the interlayer regions to assemble a strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, confined water layers, and layered mineral sheets. Figure 2 As shown, (a) is a three-dimensional structural model of the solid-liquid-solid interface, and (b) is a top view of the solid interface structure. Different colored spheres represent different atoms.

[0034] As a further implementation, when constructing the interface system, the simulation box has suitable normal and lateral dimensions, and the total number of atoms in the system is on the order of magnitude that can be stably simulated.

[0035] As a further implementation, confined systems with different hydration states (such as monolayer hydration, bilayer hydration, etc.) can be constructed by adjusting the number of water molecules added to the interlayer region. The number of water molecules in the interlayer region is determined based on the number of interlayer compensating ions and the target hydration state. This interface system is used to characterize the nanoscale confined hydration interface environment formed between clay mineral particles such as bentonite under deep-water high-head, mud compaction, or particle contact conditions.

[0036] As a further implementation, in terms of force field selection, the layered mineral lamellae can be described using a classical force field suitable for layered silicates, for example, using the ClayFF series force field to describe the layered mineral lamellae; water molecules can be described using a three-point or four-point water model, for example, using the SPC / E water model to describe water molecules; the interlayer solution and other components can be described using a general force field suitable for interfacial systems or other verified force fields, for example, using the CVFF force field to describe the interlayer solution and other organic components.

[0037] In this step, the constructed strongly hydrated confined solid-liquid-solid interface system includes: layered mineral sheets, interlayer confined water molecules, interlayer compensating ions, and different initial interlayer spacing conditions. The initial interlayer spacing can be preset to a typical value according to simulation requirements. In the subsequent bidirectional convergence verification process, different initial interface states are constructed by decreasing and increasing the initial interlayer spacing, respectively, to verify whether the interlayer structure under different evolution paths eventually converges to a stable equilibrium state.

[0038] The constructed strongly hydrated confined solid-liquid-solid interface system was subjected to geometric minimization, energy minimization, and pre-equilibrium molecular dynamics simulations to achieve a stable state. Specifically, the conjugate gradient method was used for energy minimization to eliminate unreasonable interatomic contacts; subsequently, pre-equilibrium simulations were performed under the NVT ensemble to ensure that the system temperature reached the target value and stabilized.

[0039] S2. Identify the interface piston layer and the fixed skeleton layer based on the spatial distribution of layered minerals in the normal direction.

[0040] In this step, the interface piston layer and the fixed framework layer are identified based on the spatial distribution of layered minerals in the normal direction. For example... Figure 3 As shown, the interface piston layer is a mineral surface atomic region located above the interlayer fluid region and near the confined interface, used to receive external normal forces and transmit pressure to the confined interface. In a further embodiment, the interface piston layer is allowed to undergo confined displacement in the normal direction to characterize the actual stress response during local interface compaction. The mineral surface atomic region located below the interlayer fluid region and near the confined interface is the lower interface support response layer, which participates in the interlayer force balance as a local support response interface, rather than as an independent object of additional load application.

[0041] The fixed framework layer is a deep mineral region located below the interlayer fluid region and far from the interface, used to maintain the stability of the overall mineral framework. As a further embodiment, the fixed framework layer remains fixed to provide stable support boundaries and reduce non-physical deformation of the overall framework.

[0042] S3. Based on the initial stable interface structure, establish the interlayer local equivalent pressure background, and introduce engineering disturbance pressure on the basis of the local equivalent pressure background to construct a differential pressure response system.

[0043] In this step, based on the interlayer confined water structure, electric bilayer interaction, van der Waals attraction, ion layer confinement, and particle skeleton force transmission of the initially stable interface structure of the strongly hydrated confined solid-liquid-solid interface system, a local equivalent pressure background is established. This equivalent background pressure is formed during the system's energy minimization and pre-equilibrium relaxation process. It is used to characterize the local high-constraint normal pressure state in the strongly hydrated confined interface, which is formed by confined hydration repulsion, electric bilayer interaction, ion layer confinement, and particle skeleton force transmission. The local interface pressure constraint intensity is not equivalent to the macroscopic engineering pressure level. As a further implementation, a high local constraint normal pressure state is formed inside a confined interlayer model where the interlayer water body is completely confined by two layered minerals above and below, without external exchange boundaries.

[0044] Based on a local equivalent pressure background, an engineering disturbance pressure is introduced to construct a differential pressure response system, which is used to characterize the local compaction response process of strongly hydrated confined interfaces under different engineering disturbance conditions. The engineering disturbance pressure is applied as a differential disturbance quantity under the local equivalent pressure background, rather than replacing the actual interlayer pressure state. This differential pressure response system effectively avoids the problems of instantaneous depressurization of interlayer structures, abrupt changes in local hydration structures, and sudden release of potential energy caused by the direct transition from a low-pressure system to a high-confinement state during traditional overall pressure switching processes.

[0045] As a further implementation, different levels of engineering disturbance pressure conditions can be set to progressively characterize different interface pressure conditions, such as no external load baseline, general engineering pressure, high-head engineering pressure, and extreme compaction within a nano-confined interface. The high-pressure condition is used to characterize the local extreme constraint response state within the nano-confined interface, rather than directly corresponding to the macroscopic engineering hydrostatic pressure.

[0046] S4. Based on the differential pressure response system, under the condition of fixed simulation box normal dimensions, a local normal additional force is applied to the interface piston layer to realize local interface normal loading; In this step, based on the constructed differential pressure response system, while keeping the normal dimensions of the simulation cell fixed, a local normal additional force is applied to the interface piston layer to achieve local interface normal loading. The local interface stress state and local interface normal loading method can be found in [reference needed]. Figure 4 .

[0047] Specifically, the system consists of upper and lower mineral framework layers, confined aqueous phase between layers, and ion distribution regions. During the simulation, the normal (i.e., z-axis) dimensions of the computational box are kept constant, and overall NPT compression is not used to avoid interference from overall volume changes on the interface structure. First, an engineering perturbation pressure is set at the top of the system. It does not act directly on the entire simulation chamber, but rather applies an equivalent load through an interface piston layer in the form of a localized normal force. This piston layer corresponds to the upper boundary atomic layer or an equivalent rigid loading layer, used to bear the external normal load and transfer it to the confined interface. Then, based on the target engineering disturbance pressure... The total normal additional force applied to the piston layer is calculated by relating it to the interface force-bearing area A. Furthermore, this total force is distributed to the piston layer atomic assembly, achieving discrete force loading at the atomic scale. Under this loading condition, a local equivalent normal pressure background P_local exists within the interface, formed by confined hydration repulsion, electric bilayer interaction, and van der Waals interaction. This pressure is a self-consistent result of the internal interactions of the system during relaxation. Externally... Under the combined action of the action and the internal P_local, the interlayer water structure and interface skeleton generate a coordinated response, thereby forming a local high-constraint normal force state as shown in the figure, realizing the interface mechanical characterization under differential pressure conditions.

[0048] By using a local interface normal loading method under fixed box size conditions, the local compaction response of the strongly hydrated confined interface is simulated, thereby avoiding the problems of overall box compression, abnormal pressure bearing of solid skeleton and non-physical abrupt changes in interlayer structure caused by traditional overall NPT loading.

[0049] S5. Molecular dynamics simulations were performed on strongly hydrated confined solid-liquid-solid interface systems. The system stabilization was controlled during local interface normal loading, and the simulation effectiveness was judged based on stability criteria to obtain equilibrium trajectory data. In this step, molecular dynamics simulations are performed on the strongly hydrated confined solid-liquid-solid interface system. During the local interface normal loading process, the strongly hydrated confined solid-liquid-solid interface system is stabilized to reduce the risk of dynamic instability caused by the rapid release of local potential energy under strong confinement and high pressure conditions. Finally, equilibrium trajectory data are obtained.

[0050] In this step, system stabilization control includes one or more of the following: independent control of the solid-liquid region, constraint on the bond lengths and bond angles of water molecules, periodic removal of the overall linear and angular momentum of the system, and application of local dynamic stabilization control to the locally high-response regions of the interface. Independent control of the solid-liquid region includes applying independent dynamic control to the interlayer fluid region and the interface response region respectively, and applying fixed constraints to the deep mineral framework far from the interface. Specifically, applying independent dynamic control to the interlayer fluid region and the interface response region reduces abnormal temperature fluctuations and local energy release instability during local high-pressure loading; fixing the atoms of the deep mineral framework far from the interface reduces non-physical deformation of the overall framework and long-range stress transmission; constraining the bond lengths and bond angles of water molecules reduces the risk of numerical divergence caused by high-frequency vibrations under high-pressure confinement; periodically removing the overall linear and angular momentum of the system reduces overall system drift and non-physical rotation during local high-pressure loading; and applying local dynamic stabilization control to the locally high-response regions of the interface reduces interface structural instability caused by rapid release of local potential energy. By stabilizing and controlling the system as described above, the risks of local temperature spikes, structural abrupt changes, and long-range electrostatic instability during the high-pressure loading process in a strongly hydrated confined environment can be reduced, thereby improving the stability and reliability of the simulation of the local interface compaction response.

[0051] In this step, when performing molecular dynamics simulations on the strongly hydrated confined solid-liquid-solid interface system, a canonical (NVT) ensemble stabilization control is first performed under conditions without applying a piston force to bring the interlayer fluid and the movable interface layer to a stable temperature state. Subsequently, a normal force is applied to the upper interface piston layer to conduct a local interface normal loading simulation. The validity of the simulation results is judged based on the stability criterion to evaluate whether the system has reached a stable simulation state during the strongly hydrated confined high-pressure loading process. If the simulation is valid, equilibrium trajectory data is obtained.

[0052] As a further implementation, during the local interface normal loading simulation process, system configuration data is output in stages at preset time intervals (such as obtaining system configurations corresponding to approximately 1ps, 10ps, 20ps, and 50ps) to analyze the short-time response characteristics and gradual stabilization process of the interlayer structure under different engineering disturbance pressure conditions.

[0053] As a further implementation method, the stability criteria include one or more of the following: continuous change of system potential energy without abnormal sudden drop; continuous evolution of effective free space between layers without instantaneous jump; stable temperature fluctuation of the system without persistent temperature spikes; no atomic scattering, layer crossing, or local structural collapse in the configuration snapshot during the simulation; no lost atoms or bond missing errors; no PPPM calculation crash and stable convergence of long-range electrostatic calculations.

[0054] By using the above stability criteria, the dynamic stability, interlayer structural stability, and long-range electrostatic calculation stability of the system during local interface normal loading can be comprehensively judged, thereby improving the reliability and comparability of the pressure response analysis results of strongly hydrated confined interfaces.

[0055] S6. Based on equilibrium trajectory data, interlayer structural response parameters are extracted, and combined with a two-way convergence verification method, the interlayer structure, hydration behavior, and local compaction response are analyzed.

[0056] In this step, based on the post-equilibrium trajectory data, interlayer structural response parameters are extracted, and the structural evolution and local compaction response characteristics of the strongly hydrated confined interface under different pressure conditions are analyzed accordingly. These interlayer structural response parameters include one or more of the following: effective free space parameters between layers, normal (i.e., z-axis) density distribution of water molecules and ions, radial distribution function, coordination number, mean square displacement, diffusion coefficient, and interfacial energy change.

[0057] When analyzing the extracted interlayer structure response parameters, the degree of adsorbed water enhancement, the degree of reduction of central free water, and the transformation process of free water into confined water are analyzed by the z-axis density distribution changes of water molecules and ions. The interfacial ion coordination structure, local hydration environment changes, and short-range interfacial correlation characteristics are analyzed by the radial distribution function and coordination number. The degree of dynamic confinement of interlayer fluids under different pressure conditions is analyzed by the mean square displacement and diffusion coefficient. The interfacial structural stability and interfacial interaction changes during local compaction are analyzed by the interfacial energy changes. Through the above interlayer structure response analysis, a comprehensive characterization of the local compaction behavior, hydration structure evolution, and interfacial stability of strongly hydrated confined interfaces under different pressure conditions is achieved.

[0058] To verify the stability and reliability of the interlayer structure response results under different pressure conditions, this step employs a two-way convergence verification method to verify the interlayer equilibrium structure. For example... Figure 5 As shown, when verifying the interlayer equilibrium structure using the bidirectional convergence verification method, the interlayer evolution simulation is performed starting from the initial small spacing and the initial large spacing respectively. The small spacing system is used to observe the interlayer expansion process, and the large spacing system is used to observe the interlayer compaction and contraction process. If different evolution paths eventually converge to similar interlayer structures, the current interlayer structure is determined to have reached a stable equilibrium state.

[0059] The bidirectional convergence verification mechanism described above can reduce the impact of local metastable structures on the pressure response analysis results and improve the reliability of the interlayer equilibrium structure judgment.

[0060] To verify the effectiveness of the differential pressure response simulation method for strongly hydrated confined layered mineral interfaces proposed in this embodiment, montmorillonite was used as a representative layered mineral, and the interlayer confined system was used as a representative object to simulate and analyze the local compaction response process of strongly hydrated confined interfaces under different engineering disturbance pressure conditions. The specific process is as follows.

[0061] S1. Construct a strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, a confined fluid layer, and opposing layered mineral sheets, and perform pretreatment to obtain an initial stable interface structure.

[0062] In this step, a 2:1 type TOT layered aluminosilicate structure model is constructed based on montmorillonite crystallographic parameters. Permanent layer charges are introduced according to the isomorphic substitution rule to form a sodium-based montmorillonite layered mineral lamellar model. A 6×2 supercell model of sodium-based montmorillonite lamellars is constructed using MaterialsStudio software. Water molecules and interlayer compensating sodium ions are added to the interlayer regions to assemble a strongly hydrated confined solid-liquid-solid interface system consisting of sodium-based montmorillonite lamellars – confined water layer – sodium-based montmorillonite lamellars. The simulation box size is approximately... The total number of atoms in the system is approximately 4344.

[0063] A single-layer hydrated state was selected as the representative confined hydration structure. 144 water molecules were added to the interlayer region of each sodium montmorillonite layer to characterize the interlayer confined water environment under strong hydration confinement conditions.

[0064] Furthermore, the montmorillonite lamellars are preferably described using a ClayFF force field, water molecules are preferably described using an SPC / E water model, and the interlayer solution and other organic components can be described using a CVFF force field or other classical force fields suitable for interfacial systems. The initial interlayer spacing is preferably approximately [value missing]. .

[0065] S2. Identify the interface piston layer and the fixed skeleton layer based on the spatial distribution of layered minerals in the normal direction.

[0066] In this step, the interface surface region is identified based on the normal (i.e., z-axis) coordinate range of the oxygen atoms on the mineral surface. The interface piston layer is the mineral surface atomic region located above the interlayer fluid region and close to the confined interface. It is allowed to undergo confined displacement in the normal direction to characterize the actual stress response during the local interface compaction process. The fixed skeleton layer is the deep mineral region located below the interlayer fluid region and far from the interface. It is used to maintain the stability of the overall mineral skeleton. The fixed skeleton layer remains fixed to provide a stable support boundary and reduce the non-physical deformation of the overall skeleton. The mineral surface atomic region located below the interlayer fluid region and close to the confined interface is the lower interface support response layer. It participates in the interlayer force balance as a local support response interface, rather than as an independent additional load object.

[0067] As an example, the z-axis range corresponding to the interface piston layer is preferably approximately The z-axis range corresponding to the fixed skeleton layer is preferably the upper layer. and lower levels .

[0068] S3. Based on the initial stable interface structure, establish the interlayer local equivalent pressure background, and introduce engineering disturbance pressure on the basis of the local equivalent pressure background to construct a differential pressure response system.

[0069] Based on the interlayer confined water structure, electric bilayer effect, van der Waals attraction, ion layer confinement and particle skeleton force transmission of the initially stable interface structure of the strongly hydrated confined solid-liquid-solid interface system, an interlayer local equivalent pressure background is established. On the basis of the local equivalent pressure background, engineering disturbance pressure is introduced to construct a differential pressure response system.

[0070] In this example, different engineering disturbance pressure conditions, such as 0 atm, 10 atm, 50 atm, 100 atm, 500 atm, 1000 atm, and 5000 atm, are set to progressively characterize different interface pressure conditions, including no external load baseline, general engineering pressure, high head engineering pressure, and extreme compaction within a nano-confined interface. The high-pressure condition is used to characterize the local extreme constraint response state within the nano-confined interface, rather than directly corresponding to the macroscopic engineering hydrostatic pressure.

[0071] S4. Based on the differential pressure response system, under the condition of fixed simulation box normal dimensions, a local normal additional force is applied to the interface piston layer to realize local interface normal loading.

[0072] In this step, this example does not use the traditional integral NPT box compression method. Instead, it is based on the differential pressure response system. Under the condition of keeping the normal size of the simulation box fixed, the total normal additional force applied to the interface piston layer is determined according to the correspondence between the target engineering disturbance pressure and the interface force area. The normal additional force is then distributed to the atomic region of the interface piston layer to achieve local interface normal loading.

[0073] S5. Molecular dynamics simulations were performed on a strongly hydrated confined solid-liquid-solid interface system. The system stabilization was controlled during local interface normal loading, and the simulation effectiveness was judged based on stability criteria to obtain equilibrium trajectory data.

[0074] In this step, molecular dynamics simulations are performed on a strongly hydrated confined solid-liquid-solid interface system. During local interface normal loading, stabilization controls are implemented to reduce the risk of dynamic instability caused by rapid release of local potential energy under strong confinement and high pressure conditions. In this example, independent dynamic controls are applied to the interlayer fluid region and the interface response region; fixed constraints are applied to the deep mineral framework far from the interface; constraints are applied to the bond lengths and bond angles of water molecules; and the overall linear momentum and angular momentum of the system are periodically removed to reduce the risk of overall system drift and local structural instability during local high-pressure loading.

[0075] When performing molecular dynamics simulations on a strongly hydrated confined solid-liquid-solid interface system, NVT ensemble stabilization control is first performed without applying a piston force to bring the interlayer fluid and the movable interface layer to a stable temperature state. Subsequently, a normal force is applied to the upper interface piston layer to conduct a local interface normal loading simulation. The simulation results are then evaluated for validity based on stability criteria to assess whether the system reaches a stable simulated state under high-pressure loading within the strongly hydrated confined space. If the simulation is valid, equilibrium trajectory data is obtained. During the local interface normal loading simulation, structural data is output in stages, obtaining system configurations at approximately 1 ps, 10 ps, ​​20 ps, ​​and 50 ps, ​​respectively, to analyze the short-time response and gradual stabilization process of the interlayer structure under different pressure disturbances.

[0076] S6. Based on equilibrium trajectory data, interlayer structural response parameters are extracted, and combined with a two-way convergence verification method, the interlayer structure, hydration behavior, and local compaction response are analyzed.

[0077] Interlayer structural response parameters are extracted based on equilibrium trajectory data, and a bidirectional convergence verification method is used to verify the interlayer equilibrium structure. The specific process includes: performing interlayer evolution simulations starting from initial small spacing and initial large spacing respectively; the small spacing system is used to observe the interlayer expansion process, and the large spacing system is used to observe the interlayer compaction and contraction process. If different evolution paths eventually converge to similar interlayer structures, the current interlayer structure is determined to have reached a stable equilibrium state.

[0078] Based on the post-equilibrium trajectory data, interlayer structural response parameters are extracted, and the structural evolution and local compaction response characteristics of strongly hydrated confined interfaces under different pressure conditions are analyzed accordingly. Figure 7 As shown. Figure 7In the diagram, (a) is a snapshot of the interlayer structure configuration at 0 atm, (b) is a snapshot of the interlayer structure configuration at 10 atm, (c) is a snapshot of the interlayer structure configuration at 50 atm, (d) is a snapshot of the interlayer structure configuration at 100 atm, (e) is a snapshot of the interlayer structure configuration at 500 atm, (f) is a snapshot of the interlayer structure configuration at 1000 atm, and (g) is a snapshot of the interlayer structure configuration at 5000 atm. The interlayer structure response parameters include: effective free space parameters, z-axis density distribution of water molecules and ions, radial distribution function, coordination number, mean square displacement, diffusion coefficient, and interfacial energy change. By analyzing the changes in the z-axis density distribution of water molecules and ions, we can determine the degree of surface adsorbed water enhancement, the degree of central free water reduction, and the transformation process of free water into confined water. By analyzing the evolution of effective free space parameters between layers, we can determine the degree of interlayer structural compaction and stable shrinkage characteristics under different pressure conditions. By analyzing the changes in interfacial energy, we can determine the stability of interfacial structures and the characteristics of interfacial interaction changes during local compaction.

[0079] The z-axis density distribution results indicate that as pressure increases, the degree of water molecule stratification increases, and the central free water region decreases. Gradually enriched in the interface region, and forming a more obvious interface compensation layer structure under high pressure conditions, water molecules and The z-axis density distribution variation characteristics can be found in [reference]. Figure 6 . Figure 6 In the diagram, (a) shows the z-axis density distribution of Clay O under different pressure conditions, and (b) shows the density distribution of Clay O under different pressure conditions. The z-axis density distribution diagrams are shown in (c) and (d) for Water H under different pressure conditions. The radial distribution function results indicate that under high pressure conditions... The correlation with the interface region is enhanced. Simultaneously, under conditions above 500 atm, the interlayer structure gradually shifts from a uniform compaction stage to locally non-uniform compaction characteristics; under conditions of 1000 atm and 5000 atm, the local interlayer free space further decreases, accompanied by enhanced structural fluctuations. The characteristics of local interlayer compaction and structural rearrangement under different pressure conditions can be found in [reference needed]. Figure 7 .

[0080] In this example, the variation of the effective free space parameter d_int_q90_q10 between layers under different engineering disturbance pressures is as follows: Figure 8 As shown: under 0 atm conditions, approximately Under 10 atm conditions, it is approximately Approximately 50 atm Approximately 100 atm Approximately 500 atm Under 1000 atm conditions, it is approximately Under 5000 atm conditions, it is approximately The results show that as the engineering disturbance pressure increases, the effective free space between layers generally decreases; under higher pressure conditions, the interlayer structure further undergoes local reorganization and confined compaction response.

[0081] Example 2 In a typical embodiment of the present invention, this embodiment discloses a differential pressure response simulation system for strongly hydrated confined layered mineral interfaces, comprising: The system construction module is configured to: construct a strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, a confined fluid layer, and relatively arranged layered mineral sheets, and perform preprocessing to obtain an initial stable interface structure; The interface recognition module is configured to identify the interface piston layer and the fixed skeleton layer based on the spatial distribution of layered minerals in the normal direction. The pressure response module is configured to: establish an interlayer local equivalent pressure background based on the initial stable interface structure, introduce engineering disturbance pressure on the basis of the local equivalent pressure background, and construct a differential pressure response system. The local normal loading module is configured to apply a local normal additional force to the interface piston layer based on the differential pressure response system, under the condition of fixed simulation box normal size, to achieve local interface normal loading. The system simulation module is configured to: perform molecular dynamics simulations on strongly hydrated confined solid-liquid-solid interface systems, control system stabilization during local interface normal loading, determine the effectiveness of the simulation based on stability criteria, and obtain equilibrium trajectory data; The analysis output and verification module is configured to: extract interlayer structural response parameters based on equilibrium trajectory data, and analyze the interlayer structure, hydration behavior and local compaction response by combining a two-way convergence verification method.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A differential pressure response simulation method for strongly hydrated confined layered mineral interfaces, characterized in that, include: A strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, a confined fluid layer, and opposing layered mineral sheets was constructed and pretreated to obtain an initial stable interface structure. Identify the interface piston layer and the fixed skeleton layer based on the spatial distribution of layered minerals in the normal direction; Based on the initial stable interface structure, a local equivalent pressure background is established between layers. Based on the local equivalent pressure background, engineering disturbance pressure is introduced to construct a differential pressure response system. Based on the differential pressure response system, under the condition of fixed simulation box normal dimensions, a local normal additional force is applied to the interface piston layer to achieve local interface normal loading. Molecular dynamics simulations were performed on a strongly hydrated confined solid-liquid-solid interface system. The system stabilization was controlled during local interface normal loading, and the simulation effectiveness was judged based on stability criteria to obtain equilibrium trajectory data. Interlayer structural response parameters are extracted based on equilibrium trajectory data, and the interlayer structure, hydration behavior, and local compaction response are analyzed using a two-way convergence verification method.

2. The differential pressure response simulation method for strongly hydrated confined layered mineral interfaces as described in claim 1, characterized in that, Constructing a strongly hydrated confined solid-liquid-solid interface system specifically includes: constructing a silicate mineral sheet model with a 2:1 layered structure based on the crystallographic parameters of the target layered mineral, introducing permanent layer charges according to the isomorphic substitution rule, and adding interlayer compensation cations to form the target layered mineral sheet model. Based on the target layered mineral sheet model, a supercell model of the layered mineral sheet is constructed, and a preset number of water molecules and compensating ions are added to the interlayer region to assemble a strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, confined water layers, and layered mineral sheets.

3. The differential pressure response simulation method for strongly hydrated confined layered mineral interfaces as described in claim 1, characterized in that, The interface piston layer is a mineral surface atomic region located above the interlayer fluid region and close to the confined interface, used to receive external normal forces and transmit pressure to the confined interface; the fixed framework layer is a deep mineral region located below the interlayer fluid region and far from the interface, used to maintain the stability of the overall mineral framework. The mineral surface atomic region located below the interlayer fluid region and near the confined interface is the lower interface support response layer. It participates in the interlayer force balance as a local support response interface, rather than as an independent additional load object.

4. The differential pressure response simulation method for strongly hydrated confined layered mineral interfaces as described in claim 1, characterized in that, The interlayer local equivalent pressure background is established based on the initial stable interface structure. Specifically, based on the interlayer confined water structure, electric double layer effect, van der Waals attraction, ion layer confinement and particle skeleton force transmission of the initial stable interface structure of the strongly hydrated confined solid-liquid-solid interface system, the interlayer local equivalent pressure background is established to characterize the local high-constraint normal pressure state formed by confined hydration repulsion, electric double layer effect, ion layer confinement and particle skeleton force transmission in the strongly hydrated confined interface. The local interface pressure constraint intensity is not equivalent to the macroscopic engineering pressure level.

5. The differential pressure response simulation method for strongly hydrated confined layered mineral interfaces as described in claim 1, characterized in that, The local interface is subjected to normal loading, which specifically includes: based on the constructed differential pressure response system, while keeping the normal size of the simulation box fixed, the total normal additional force applied to the interface piston layer is determined according to the correspondence between the target engineering disturbance pressure and the interface force area, and the normal additional force is distributed to the atomic region of the interface piston layer to realize the local pressure transmission at the interface.

6. The differential pressure response simulation method for strongly hydrated confined layered mineral interfaces as described in claim 1, characterized in that, Stabilization control of the system includes one or more of the following: applying independent dynamic control to the interlayer fluid region and the interface response region respectively; applying fixed constraints to the deep mineral framework far from the interface; applying constraints to the bond length and bond angle of water molecules; periodically removing the overall linear momentum and angular momentum of the system; and applying local dynamic stabilization control to the locally high-response region of the interface.

7. The differential pressure response simulation method for strongly hydrated confined layered mineral interfaces as described in claim 1, characterized in that, Stability criteria include one or more of the following: continuous change in system potential energy without abnormal sudden drop; continuous evolution of effective free space between layers without instantaneous jump; stable temperature fluctuation of the system without persistent temperature spikes; no atomic scattering, layer crossing, or local structural collapse in the configuration snapshot during the simulation; no atomic loss or bond loss errors; no PPPM calculation crash and stable convergence of long-range electrostatic calculations.

8. The differential pressure response simulation method for strongly hydrated confined layered mineral interfaces as described in claim 1, characterized in that, Interlayer structural response parameters include one or more of the following: effective free space parameters between layers, z-axis density distribution of water molecules and ions, radial distribution function, coordination number, mean square displacement, diffusion coefficient, and interfacial energy change.

9. The differential pressure response simulation method for strongly hydrated confined layered mineral interfaces as described in claim 1, characterized in that, The bidirectional convergence verification method specifically includes: performing interlayer evolution simulations starting from the initial small spacing and the initial large spacing respectively. The small spacing system is used to observe the interlayer expansion process, and the large spacing system is used to observe the interlayer compaction and contraction process. If different evolution paths eventually converge to similar interlayer structures, the current interlayer structure is determined to have reached a stable equilibrium state.

10. A differential pressure response simulation system for strongly hydrated confined layered mineral interfaces, characterized in that, include: The system construction module is configured to: construct a strongly hydrated confined solid-liquid-solid interface system consisting of layered mineral sheets, a confined fluid layer, and relatively arranged layered mineral sheets, and perform preprocessing to obtain an initial stable interface structure; The interface recognition module is configured to identify the interface piston layer and the fixed skeleton layer based on the spatial distribution of layered minerals in the normal direction. The pressure response module is configured to: establish an interlayer local equivalent pressure background based on the initial stable interface structure, introduce engineering disturbance pressure on the basis of the local equivalent pressure background, and construct a differential pressure response system. The local normal loading module is configured to apply a local normal additional force to the interface piston layer based on the differential pressure response system, under the condition of fixed simulation box normal size, to achieve local interface normal loading. The system simulation module is configured to: perform molecular dynamics simulations on strongly hydrated confined solid-liquid-solid interface systems, control system stabilization during local interface normal loading, determine the effectiveness of the simulation based on stability criteria, and obtain equilibrium trajectory data; The analysis output and verification module is configured to: extract interlayer structural response parameters based on equilibrium trajectory data, and analyze the interlayer structure, hydration behavior and local compaction response by combining a two-way convergence verification method.

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