Pressure Dissipation Research Articles

GEOTEHNIČKI ASPEKTI PETRINJSKOG POTRESA I NEKE SANACIJE

Magnitude MW6.4 Petrinja earthquake on 29 December 2020, caused liquefaction in the fields, under some houses, under some bridges, damages to some roads and bridges, several levees, some landslides and rockfalls, and wide opening of sinkholes. Several levees along the Kupa and Sava rivers were damaged – mostly longitudinal cracks were noticed near or on the body of those levees, often followed by sandy soil ejected to the surface – on these locations some layers of soil containing sand were discovered on the depth of 5 to 8 m, which obviously liquefied during the earthquake – causing strong movements of the levee body, cracking and lateral spreading. Designs of the solutions are shown with changes made due to the very unfavourable weather conditions in long and heavy periods of rain. Design of a soil improvement is shown for a bridge which suffered settlelments due to liquefaction of the foundation soil. An example of successful foundation is shown – of a reservoir on a soil improved by gravel columns – which helped the pore pressure dissipation after the earthquake. The paper gives some information on other investigation and other remediation works.

Modelling smear effect of vertical drains using a diameter reduction method

Vertical drains are used to accelerate consolidation of clays in ground improvement projects. Smear zones exist around these drains, where permeability is reduced due to soil disturbance caused by the installation process. Hansbo solution is widely used in practice to consider the effects of drain discharge capacity and smear on the consolidation process. In this study, a computationally efficient diameter reduction method (DRM) obtained from the Hansbo solution is proposed to consider the smear effect without the need to model the smear zone physically. Validated by analytical and numerical results, a diameter reduction factor is analytically derived to reduce the diameter of the drain, while achieving similar solutions of pore pressure dissipation profile as the classical full model of the smear zone and drain. With the DRM, the excess pore pressure u obtained from the reduced drain in the original undisturbed soil zone is accurate enough for practical applications in numerical models. Such performance of DRM is independent of soil material property. Results also show equally accurate performance of DRM under conditions of multi-layered soils and coupled radial-vertical groundwater flow.

Pressure Model Study on Synchronous Grouting in Shield Tunnels Considering the Temporal Variation in Grout Viscosity

The grout pressure in the shield tunnel tail void during synchronous grouting is the key to controlling ground settlement and restraining the segment. However, the circumferential, longitudinal, and radial distribution of grout pressure considering the temporal variation in grout viscosity has not been well explored yet. In this study, a theoretical model of grout pressure distribution and dissipation considering the temporal variation in Bingham grout viscosity was established. The simulation results of the pressure model were verified by field-measured data. The results showed that the radial and longitudinal distributions of grout pressure considering the temporal variation in grout viscosity were closer to the field-measured data. The impacts of the main parameters on the pressure distribution and dissipation were analyzed. Compared with the effect of the shield tail void thickness, tunnel radius and yield shear stress have greater effects on grout pressure during the circumferential filling phase. During the longitudinal and radial diffusion phases, the increase in soil porosity and permeability coefficient was conducive to grout diffusion. The increase in the grout viscosity reduces the pressure loss during the grout flow process. The results of this research can provide a theoretical basis for the grout design process in shield tunnels.

Experimental Investigation on the Post-liquefaction Behavior of Sands in Simple Shear Conditions

Abstract Experimental evidence shows that earthquake induced liquefaction can occur more than once in sandy soils. Moreover, despite an increase in soil density caused by the dissipation of the excess pore pressure induced by earthquakes, the liquefaction resistance of soils that have experienced liquefaction may be lower than that of virgin soils. This paper offers insight into this topic starting from the analysis of the undrained monotonic behavior of post-liquefied sands by means of tests performed with a simple shear cell equipped with flexible boundaries, which maintains a constant diameter to guarantee the “K0-condition.” The control system of cyclic, reconsolidation, and monotonic phases is described in detail. The experimental results show that neither the relative density, effective confining stress, cyclic stress ratio, nor the direction of shear strain play important roles in the monotonic behavior of post-liquefied soils. Moreover, the comparison between the monotonic response of virgin and post-liquefied soils (prepared by moist tamping technique) shows that it is not affected by the stress–strain history experienced by soils. It can be explained through a microstructural interpretation. According to which, the initial soil fabric generated with the moist tamping method and that formed during liquefaction remain almost unchanged because of the rotation of principal stress directions occurring during simple shear tests. A further confirmation is given by the results of tests performed on specimens prepared by air pluviation method.

Prediction Analysis on Coefficient of Consolidation Values in Improved Soft Clays

Consolidation is a phenomenon in soil mechanics that often causes geotechnical problems. One solution to overcome consolidation phenomena is by speeding up process of pore water pressure dissipation. The type of soil improvement to upgrade the performance of soft clay is by applying pre-fabricated vertical drain (PVD) and pre-compression simultaneously. Geotechnical instrumentations such as settlement plates, piezometers, and inclinometers were installed at the field of study to monitor magnitude of settlement during consolidation process. After the final settlement was achieved, the consolidation parameters such as coefficient of consolidation, and rate of settlement, were back calculated. Prediction analysis of consolidations parameters was performed by means of Asaoka method. The results of this study is very interesting and provide useful engineering information. It is interesting to note that this case study may be beneficial use to practicing engineers and researchers.

Coupled processes of groundwater dynamics and land subsidence in the context of active human intervention, a case in Tianjin, China

To address the crisis of water shortage in the North China Plain, the Chinese government implemented the South-to-North Water Transfer Project (SNWTP). In this context, Tianjin, one of the main beneficiaries of this project, has been relieved from water shortages and begun to implement Groundwater Management Plans (GMP) since 2018, which undoubtedly have a significant effect on the groundwater recovery. Meanwhile, this provides a good case for studying the coupled process of ground settlement and groundwater dynamics, especially the soil deformation pattern driven by groundwater level (GWL) rebound. To analyze these issues in detail, field well data was collected to depict groundwater flow field. Moreover, geodetic data was also collated, including leveling, GPS, and InSAR, so that a vertical deformation field with high spatiotemporal resolution could be generated. The results reveal that the GWL of the third confined aquifer which is the main exploitation layer in Tianjin recovered significantly since 2018 with a rate of 2.1 m/yr. The dynamic deformation patterns indicate that the area of land subsidence cones in Tianjin has reduced significantly, accompanied by a sharply declining subsidence rate (decreased from −32.2 mm/yr to −4.5 mm/yr.). Particularly, a significant poroelastic rebound has occurred in the Wuqing and Beichen districts since 2020. Furthermore, due to the delayed pore pressure dissipation in the aquitard, we find a time delay of 0.3–5.5 years between land subsidence and GWL time series, which is far less than that estimated by hydrogeological parameters, as the latter ignored the recharge and recovery capacity of the aquifer system. Finally, an evolution models in Tianjin was presented to illustrate interactive process among the deformation, pore pressure, and hydraulic head. In general, the SNWDP and the GMP has restored the pore pressure of aquifer, reduced the land subsidence, and alleviated the groundwater storage depletion of Tianjin.

Integration of Sentinel–1 and Landsat–8 data for identifying deformation risk of hydraulic engineering in seasonally frozen salinization regions

Hydraulic engineering has positive effects on agricultural production and soil desalination. However, freeze–thaw cycles can cause instability in canal slopes, emphasizing the need for effective deformation monitoring. Using Sentinel-1B data acquired from November 2017 to August 2019 and applying the small baseline subset (SBAS) InSAR method, two unstable canal segments with vertical deformation rates exceeding –40 mm/year were identified in Songyuan, Northeast China. The canal slopes uplifted in winter and experienced accelerated subsidence in spring, with the shady slope experiencing a deformation rate approximately 10 mm/year faster than the sunny slope. Further investigation, integrating Landsat–8 data collected from November 2017 to August 2019, revealed that the shady slope received less thermal radiation than the sunny slope, with an average annual temperature difference on the land surface of approximately 1 ℃. In winter, the saline–alkali soil particles formed a thick unfrozen water film, which, driven by temperature and soil–water gradients, migrated towards the freezing front, froze, and caused soil frost heave. The shady slope experienced longer freezing periods and deeper frozen depths, up to 240 cm, causing more unfrozen water migration and greater uplift deformation than the sunny slope. In spring, as temperature rose, the soil thawed from the surface downward. Notably, the shady slope thawed at a slower rate than the sunny slope, forming a frozen lens near a depth of 100 cm. Frozen lens acted as a barrier for meltwater infiltration, impeding the dissipation of pore water pressure, making the shady slope prone to surface landslides. The integration of multiple data sources is beneficial for identifying deformation risk in hydraulic engineering.

Micro hydro power generation in water distribution networks through the optimal pumps-as-turbines sizing and control

Sustainable use of water and energy sources is a crucial challenge for smart and resilient urban water infrastructure. At this aim, this study presents a methodology for implementing and selecting pumps-as-turbines (PaTs) in water distribution networks (WDNs) to minimise leakage losses and maximise energy recovery. A novel dynamic control algorithm for PaTs is proposed, which optimises the pressure dissipation while granting a minimum pressure head in the network. The digital hydraulic model of a WDN, which incorporates the developed control strategy, outputs the available pressure heads and flow rates of each PaT for an extended period simulation. The entire simulated data series are fed into a new algorithm to select the best machine to be installed to achieve a reliable solution under realistic and varying conditions. Finally, this methodology is applied to a real test case, improving the sustainability and energy efficiency of a mountainous WDN by enhancing the water-energy nexus.

Seismic Performance of Drained Piles in Layered Soils.

The provision of drains to geotechnical elements subjected to strong ground motion can reduce the magnitude of shaking-induced excess pore pressure and the corresponding loss of soil stiffness and strength. A series of shaking table tests were conducted within layered soil models to investigate the effectiveness of drained piles to reduce the liquefaction hazard in and near pile-improved ground. The effect of the number of drains per pile and the orientation of the drains relative to the direction of shaking were evaluated in consideration of the volume of porewater discharged, the magnitude of excess pore pressure generated, and the amount of de-amplification in the ground's motion. The following main conclusions can be drawn from this study. Single, isolated piles and a group of drained piles were tested in three series of shake table tests. Relative to conventional piles, the drained piles exhibited improved performance with regard to the generation and dissipation of excess pore pressure and stiffness of the surrounding soil, with increases in performance correlated with increases in the discharge capacity of the drained pile. The acceleration time histories observed within the pile-improved soil indicated a coupling of the rate and magnitude of porewater discharge, excess pore pressure generated, and de-amplification of strong ground motion. The amount of de-amplification reduced with increases in the number of drains per pile and corresponding reductions in excess pore pressure. The improved performance should prove helpful in the presence of sloping ground characterized with low-permeability soil layers that inhibit the dissipation of pore pressure and have demonstrated the significant potential for post-shaking slope deformation.

A semi-analytical solution for consolidation of soft ground improved by locally permeable pipe piles under time-dependent loads

Excessive pore-water pressure in soft soil can compromise pile bearing capacity, leading to foundation failure and posing a risk to structure stability. Hence expedited dissipation of excess pore-water pressure is critical. Permeable pipe piles offer an alternative to accelerating this consolidation process. In this study, a modified vertical equal-strain consolidation model of composite foundations with locally permeable pipe piles under arbitrary time-dependent loads is investigated. The integral transform and boundary transform methods are used to obtain a semi-analytical solution to this consolidation problem. The proposed solution’s validity and correctness are further confirmed via theoretical degradation and numerical analysis. Subsequently, a sensitivity analysis in terms of opening parameters, pile-soil modulus ratio, soil’s hydraulic conductivity ratio and pile’s length-diameter ratio is conducted. The results indicate that the consolidation rate of the permeable pipe pile composite foundations demonstrates a significant enhancement over impermeable pipe pile composite foundations, especially for deep and soft foundations with high hydraulic conductivity ratios. The consolidation efficiency improves with the increase of pile’s opening ratio, opening length and opening depth until it reaches a plateau at larger opening parameters. The research can provide theoretical support for design and construction of infrastructure with permeable pipe pile composite foundations.

Investigating Deformation Mechanism of Earth-Rock Dams with InSaR and Numerical Simulation: Application to Liuduzhai Reservoir Dam, China

Ground deformation is the direct manifestation of the earth-rock dam's hazard potential. Therefore, it is essential to monitor deformation for dam warning and security evaluation. The Liuduzhai Dam, a clay-core dam of a large reservoir in China, was reinforced with plastic concrete cut-off walls between 13 January 2009 and 29 May 2010, as it was subject to leakage and deformation. However, the deformation development and the mechanism of the dam are still unclear. In this study, the deformation fields before and after the reinforcement of the Liuduzhai Dam were yielded by using the Interferometric Synthetic Aperture Radar (InSAR) technique. Furthermore, a numerical simulation method was employed to obtain the dynamic seepage field of the dam during the InSAR observation period. The results indicated that the average deformation velocity and maximum deformation velocity are −11.7 mm/yr and −22.5 mm/yr, respectively, and the cumulative displacement exceeds 100 mm, which shows typical continuous growth characteristics in a time series. In contrast, the dam deformation tended to be stable after reinforcement, with the average deformation velocity and maximum deformation velocity being −0.4 mm/yr and −1.2 mm/yr, respectively, behaving as cyclical deformation time series. According to the results of InSAR and seepage analysis, it is shown that: (1) dynamic seepage was the main mechanism controlling dam deformation prior to reinforcement; (2) the concentrated load caused by construction and the rapid dissipation of pore water pressure caused by the sudden drop of the infiltration line were the reasons for the acceleration of deformation during and after construction; and (3) the plastic concrete cut-off walls effectively reduced the dynamic seepage field, while the water level fluctuations were the main driving factor of elastic deformation of the dam after reinforcement. This study provides a novel approach to investigating the deformation mechanism of earth-rock dams. Furthermore, it has been confirmed that InSAR can identify the seepage deformation of dams by detecting surface movements. It is recommended that InSAR deformation monitoring should be incorporated into future dam safety programs to provide detailed deformation signals. By analyzing the temporal and spatial characteristics of the deformation signal, we can identify areas where dam performance has degraded. This crucial information aids in conducting a comprehensive dam safety assessment.

Study on the consolidation behavior of horizontal drainage foundation under complex aquifer formation conditions in karst regions

Introduction: The consolidation behavior of horizontal drainage foundation under complex aquifer conditions in karst areas is a hot topic in the field of geotechnical engineering.Methods: This paper presents a modified piecewise-linear model for plane-strain consolidation. In this model, the distributed drainage boundary was used to describe the drainage performance of soil layer boundaries, and the UH model considering the time effect was selected to reflect soil’s rheological property. Through comparison with existing research, the validity of the calculation model in this paper was verified. Then several examples were used to analyze the consolidation behavior of the foundation under the combined action of rheological effect and distributed drainage boundaries.Results and discussion: Numerical studies show that the phenomenon of the increase of excess pore pressure exists in the foundation of the distributed drainage boundary after considering the rheology in the early stage of consolidation. Moreover, the larger the secondary consolidation coefficient and the initial over-consolidation parameter, or the smaller the pave rate and the thickness-width ratio, the above phenomenon is more obvious. In terms of the dissipation of the pore water pressure, the larger the secondary consolidation coefficient and the initial over-consolidation parameter, the slower the pore pressure dissipation, and the smaller the pave rate or the thickness-width ratio can achieve the above effects. In terms of the impact on settlement, the above-mentioned parameters are consistent, that is, the larger the corresponding parameter, the larger the corresponding settlement value.

Analysis of nonlinear rheological consolidation with vertical drains: large or small strain

Given the importance of vertical drainage systems in facilitating the stability of soft ground, this paper presents a feasibility study of small-strain consolidation solutions with vertical drains and a quantitative comparison with large-strain consolidation solutions. This solution incorporates essential factors, such as non-Darcian vertical and radial flows, nonlinear void ratio and permeability relationship, initial self-weight stress, elastic viscoplastic constitutive equation, and time-dependent loading. In the design of vertical drains for large and small deformation consolidation equations are comprehensively addressed. The numerical results obtained by the finite difference method demonstrate that the conventional small-strain consolidation method for soft clay has the potential to overestimate the dissipation of excess pore pressure and underestimate the settlement at the later stage, yet correctly assess the effective stress reduction during the initial loading period. Based on the comparison of consolidation data, the relative difference in settlement between large-strain and small-strain consolidation theories will exceed 5% as the accumulated vertical strain reaches about 13%. Another threshold exists for the ratio of the soil thickness to the influence radius (H / r e) to affect the consolidation rate, whether or not the self-weight stress is captured.

Experimental study of underwater explosions below a free surface: Bubble dynamics and pressure wave emission

The current work experimentally studies the complex interaction between underwater explosion (UNDEX) bubbles and a free surface. We aim to reveal the dependence of the associated physics on the key factor, namely, the dimensionless detonation depth γ (scaled by the maximum equivalent bubble radius). Four typical bubble behavior patterns are identified with the respective range of γ: (i) bubble bursting at the free surface, (ii) bubble jetting downward, (iii) neutral collapse of the bubble, and (iv) quasi-free-field motion. By comparison of the jet direction and the migration of the bubble centroid, a critical value of γ is vital for ignoring the effects of the free surface on UNDEX bubbles. Good agreements are obtained between the experimental data and Zhang equation [Zhang et al., “A unified theory for bubble dynamics,” Phys. Fluids 35, 033323 (2023)]. Additionally, the dependence of the pressure signals in the flow field on γ is investigated. The peak pressure, impulse, and energy dissipation in the UNDEX are investigated.

Seismic site response analysis of liquefiable soil deposits focusing on the ground surface response spectrum

A numerical algorithm is developed for conducting one-dimensional non-linear ground response analysis of layered sites, capable of reproducing liquefaction phenomena and accounting for the simultaneous dissipation of excess pore water pressure through soil grains. Τhe shear wave propagation algorithm is based on the plasticity constitutive model for sand Ta-Ger, expressed in a one dimensional p-q space form. This model demonstrates remarkable versatility in representing complex patterns of the cyclic behavior of sand, such as stiffness decay and strength reduction due to pore-water pressure buildup. The calibration of the model is based on shear modulus reduction and damping curves for drained loading conditions, as well as liquefaction resistance curves for undrained conditions. A detailed presentation of the numerical model formulation is provided, outlining the numerical approach for solving the wave propagation and consolidation differential equations. To validate model predictions, the recorded seismic ground response of the Port Island array during the 1995 Kobe earthquake is utilized. Furthermore, the model is applied to estimate the elastic response spectra at the surface of soil profiles with liquefiable layers (ground type S2) as per EC8:2004. The investigation involves the ground response analysis of various soil p3rofiles, all including a liquefiable zone, excited by a suite of earthquake motions at their base. The acceleration time histories are extracted from the PEER Ground Motion Database, having characteristics compatible with the NGA-estimated response spectrum at the bedrock as well as key seismological parameters such as the earthquake magnitude Mw and the horizontal distance from the fault RJB. Two different methods are employed for selecting the base excitations: amplitude-scaled records to match a target response spectrum and spectral-matched records. From the results, an idealized response spectrum is derived in terms of the design spectrum parameters S, η, ΤΒ and TC. The findings demonstrate that the idealized ground surface response spectrum is minimally sensitive to the method used for base excitation selection.

Monotonic and Cyclic Simple Shear Response of Well-Graded Sandy Gravel Soils from Wellington, New Zealand

In the 2016 Kaikoura earthquake, liquefaction of gravelly soils from reclaimed fills occurred in CentrePort, Wellington, New Zealand. This study presents constant volume monotonic and cyclic simple shear tests on well-graded gravel with sand collected from CentrePort. A large-scale cyclic simple shear device is utilized to evaluate the monotonic, cyclic, and postcyclic responses of the sandy gravel soils. Specimens prepared at various relative densities were subjected to a vertical effective stress of 100 kPa and then monotonically and cyclically sheared. After the cyclic loading, the postcyclic response was evaluated, including volumetric compression or monotonic shear with or without dissipation of excess pore water pressure. Shear wave velocity was measured before and after the cyclic loading. The results show that the well-graded sandy gravel has a high potential for liquefaction, with higher relative density specimens having higher liquefaction resistance. Postcyclic volumetric strain is primarily correlated with density and maximum shear strain during cyclic loading. Postcyclic reconsolidation causes densification of the liquefied specimens, resulting in higher monotonic shear resistance, while postcyclic monotonic shear without dissipation of excess pore water pressure reveals that substantial shear strain is required to develop the shear resistance. Shear wave velocity was significantly reduced after liquefaction, but recovered to slightly higher than its precyclic shear values after reconsolidation. Compared to other gravelly and sandy soils, the well-graded sandy gravel showed a similar or slightly higher liquefaction resistance than gap-graded and uniform gravels. Moreover, the well-graded sandy gravel had a relatively lower ultimate postcyclic volumetric strain due to a small variation between its maximum and minimum void ratios. The results advance our understanding of the liquefaction resistance and subsequent postcyclic responses of the well-graded sandy gravel soils.

Behaviour of 60-year-old trial embankments on peat

The search for low cost solutions for roads on peatlands inspired the construction of four full scale trial embankments at two sites in Norway in the early 1960's. The embankments are still accessible and this work was motivated by present day needs to develop environmentally sustainable solutions to such problems. The embankments were constructed using locally sourced sand and sawdust and have behaved very well with the sawdust settling beneath the water table as designed and remaining in perfect condition some 60 years later. A detailed characterisation of the distinctly different peat at the two sites is presented and it is shown that the peat properties are as expected from local and international experience. Laboratory work on the sawdust showed that it behaves like a highly compressible fibrous peat. Short-term embankment settlement behaviour was controlled by the level of applied load whereas long-term creep settlements were governed by the peat consolidation properties. Pore water pressures dissipated unexpectedly quickly. Modelling using the Soft Soil Creep model in PLAXIS captured both short- and long-term settlements and the pore pressure dissipation well.

Investigation of coupled hydro-mechanical modelling of hydraulic fracture propagation and interaction with natural fractures

Various fracture patterns may develop through hydraulic fracture propagation and interaction with natural fractures which may substantially enhance connectivity and connected fracture surface area in low-permeability formations. Key factors controlling this behavior are analyzed using the continuum simulator TOUGHREACT-FLAC3D that couples the evolution of stress and deformation (FLAC3D) with reactive fluid flow (TOUGHREACT) in fractured rock. The three potential interaction scenarios are accommodated - for the hydraulic fracture to directly cross, stay arrested by, or reinitiate from the intersected natural fracture. The results show that the combined effects of approach-angle and differential stress affect the normal closure response acting on fractures. Also, larger approach-angles, greater stress differences, and higher fracture shear strength favor direct crossing, with tensile stresses more readily transferred to the far-side of the approached natural fracture. Higher injection rates accelerate buildup of wellbore and fracture pressures which lead to more rapid propagation of the hydraulic fracture. Higher injection rates also increase the wellbore pressure and pressure gradient when injection rate exceeds leak-off rate of fractures arrested by the natural fracture. The presence of only single natural fractures results in faster hydraulic fracture propagation and greater propagation length driven by higher developed wellbore pressures than where dual natural fractures are present. The presence of dual parallel natural fractures hinders the propagation of the hydraulic fracture along its preferred original path as a result of greater and redistributed leak-off and diminution of pressure through the natural fractures. Increased natural fracture permeability slows hydraulic fracture propagation by increasing fluid flow and resulting pressure dissipation by the natural fractures. Combined, these factors influence mechanisms of fracture propagation and interaction, and evolution of flow paths, which are essential in design of hydraulic fracturing treatments, hydro-mechanical characterization and prediction of the response of stimulated fracture networks.

Centrifuge modeling of the run-out behavior of fly ash deposits subjected to a loss of confinement

Numerous industries are concerned by the humanitarian, environmental, and economic consequences of debris flows, landslides, and material run-outs. However, the run-out behavior following a loss of confinement, e.g., dam failure, is not well understood. The material’s complex constitutive behavior means multiple mechanisms contribute to the deformation, e.g., slope instability, seepage forces, erosion, or static liquefaction. In this study, centrifuge models of fly ash deposits, with varying initial deposit density and water table height, were subjected to a rapid loss of lateral confinement. Deformation, pore pressure, and water content measurements were used to investigate and separate the mechanisms governing the run-out. Static liquefaction was observed in deposits initially looser than the critical state and led to a rapid material outflow. Slope instability was the initial failure mechanism for denser deposits or those with reduced water tables, with transient stability due to dilation-induced negative excess pore pressures followed by progressive failures caused by seepage pressures from drainage and pore pressure dissipation. Cone penetration tests, performed before the loss of confinement at different penetration rates, were used to characterize the material run-out and volume change tendencies and demonstrate a practical tool for assessing the run-out risk of deposits in the field.

Pore‐Scale Determination of Residual Gas Remobilization and Critical Saturation in Geological CO2 Storage: A Pore‐Network Modeling Approach

AbstractRemobilization of residually trapped CO2 can occur under pressure depletion, caused by any sort of leakage, brine extraction for pressure maintenance purposes, or simply by near wellbore pressure dissipation once CO2 injection has ceased. This phenomenon affects the long‐term stability of CO2 residual trapping and should therefore be considered for an accurate assessment of CO2 storage security. In this study, pore‐network modeling is performed to understand the relevant physics of remobilization. Gas remobilization occurs at a higher gas saturation than the residual saturation, the so‐called critical saturation; the difference is called the mobilization saturation, a parameter that is a function of the network properties and the mechanisms involved. Regardless of the network type and properties, Ostwald ripening tends to slightly increase the mobilization saturation, thereby enhancing the security of residual trapping. Moreover, significant hysteresis and reduction in gas relative permeability is observed, implying slow reconnection of the trapped gas clusters. These observations are safety enhancing features, due to which the remobilization of residual CO2 is delayed. The results, consistent with our previous analysis of the field‐scale Heletz experiments, have important implications for underground gas and CO2 storage. In the context of CO2 storage, they provide important insights into the fate of residual trapping in both the short and long term.