Pore Water Pressure Characteristics Research Articles

Model test on dynamic response of coral sand in island dredging airport under wave, tidal and aircraft landing load

The construction of an island airport on a coral reef will inevitably encounter wave, tidal and aircraft takeoff and landing loads. To study the dynamic response of the coral sand island airport under these loads, a 1:50 laboratory model test was conducted with Meiji Reef Airport as the engineering background. The model test studied the pore water pressure characteristics of the coral sand strata beneath the airport runway under wave loads with different wave heights, tidal loads with different tidal heights, and aircraft impact loads with different cyclic loading times. Additionally, the displacement characteristics of the coral sand strata beneath the airport runway under the aircraft impact loads with different cyclic loading times were also studied. The results show that the pore water pressure of coral sand strata under the airport runway decreases with the increasing offshore distance under the wave and tidal loads. The change of wave height has little influence on the pore water pressure of coral sand strata, while the change of tidal water level has a significant effect on it. As the number of aircraft impact load cycles increases, the cumulative excess pore pressure in the coral sand strata under the airport runway no longer increases and plastic deformation occurs. The research can provide a reference for the runway foundation treatment of the island airport under construction and planning.

Study of the Pore Water Pressure Development Characteristics of PHC Pipe Piles in Soft Soil Foundations

When constructing hollow prestressed high-strength concrete (PHC) pipe piles in soft soil foundations, the generation and dissipation of pore water pressure can induce negative friction on the pile. This phenomenon increases the settlement of the pile foundation and, in severe cases, can lead to pile deflection and flotation. To further investigate the development characteristics of pore water pressure during PHC hollow pipe pile driving in soft soil, this study combined existing theories and numerical models to analyze the generation and influence areas of pore water pressure. Field tests were conducted at three different sites: an untreated site, a surcharge preloading site, and a site treated with cement mixing piles and well dewatering. These tests monitored and analyzed the horizontal and vertical development and behavior of pore water pressure during pile driving at each site. The results indicate that during the pile driving process, when the horizontal distance from the pile center is 3d and 9d, the peak values of the excess pore water pressure in the site treated with cement mixing piles and well dewatering are 117 kPa and 100 kPa. After pile driving is completed, they decrease to 50 kPa and 48 kPa, respectively. The peak values of excess pore water pressure in the surcharge preloading site are 122 kPa and 97 kPa, and after pile driving, they decreased to 80 kPa and 21 kPa, respectively. The peak values of excess pore water pressure in untreated sites are 140 kPa and 121 kPa; after pile driving, they decreased to 82 kPa and 60 kPa, respectively. Pore water pressure increases with the depth of pile driving and decreases with distance from the pile driving location. The peak pore water pressure and dissipation rate during construction were found to be higher at the untreated site compared to the other two sites. Therefore, during pile sinking in soft soil foundations, dewatering and driving drainage boards are effective methods for reducing pore water pressure and accelerating its dissipation. These findings provide a theoretical basis and technical support for ensuring the safety of engineering constructions.

Model Test Study of Rainfall Factors on Failure Process of Xiashu Loess Slope with Gravel Layer

Rainfall is an important factor affecting the stability of Xiashu loess slope, so it is particularly important to understand the infiltration law and induction process of rainfall in Xiashu loess slope. In this paper, a Xiashu loess slope model with a slope ratio of 1 : 1.2 is constructed in the model box. The rainfall infiltration law, vertical stress characteristics, pore-water pressure characteristics, and deformation failure mode of the slope under two different rainfall types and four different rainfall degrees are analyzed. The instability and failure mechanism of Xiashu loess slope with gravel layer under different rainfall conditions is studied. The test results show that the influence of rainfall intensity factors on the gravel soil slope is mainly reflected in the degree of erosion of the slope. With the increase in rainfall frequency and intensity, the rainfall infiltration rate gradually increased, reached the highest value after standing, and then decreased with the increase of rainfall intensity. Rainfall has a great influence on the pore-water pressure in the gravel soil slope, and the pore-water pressure at the monitoring point of the slope toe changes the most. The vertical stress curve will change abruptly in the later stage of intermittent rainfall and during continuous rainfall.

LIQUID-SOLID COUPLING RESPONSE OF SURROUNDING ROCK MASS OF LARGE-DIAMETER RIVER-CROSSING SHIELD TUNNEL

The purpose is to investigate the response of seepage field, displacement field and stress field in the surrounding rock mass during dynamic tunneling in soft soil area. Relied on a large-diameter river-crossing shield tunnel project, considering driving force, shield tail grouting pressure, and the friction resistance between the shield shell and the soil, a three-dimensional fine tunnel model considering the liquid-solid coupling effect in the soil during dynamic tunneling was established by employing the finite difference method. The response characteristics of pore water pressure, displacement and stress in the surrounding rock mass were obtained. The results show that during shield tunneling and shield tail grouting, the pore water pressure in the range of 0.5 times the hole diameter around the tunnel decreases and increases respectively due to the liquid-solid coupling in the surrounding rock mass. When the shield tunneling moves away, the pore water pressure of the soil near the vault decreases, and the pore water pressure near the tunnel arch bottom increases. The impact range of shield tail grouting on the vertical settlement of the upper soil is about 0.5 times the hole diameter. The shield tail grouting can effectively reduce the vertical settlement of the top soil and slow down the vertical uplift of the bottom soil. During shield tunneling the vertical stress distribution of the soil above the vault of the working position and around the excavation surface is funnel-shaped, and the vertical stress around the excavated tunnel decreases.

Numerical Simulation Study on the Distribution Characteristics of Precipitation Seepage Field in Water-Rich Ultra-Thick Sand and Gravel Layer

The distribution characteristics of a seepage field generated by precipitation affects the deformation damage of the geological body and engineering geological stability, especially a seepage field with a water-rich ultra-thick sand and gravel layer. In order to study the seepage field distribution characteristics of a water-rich ultra-thick sand and gravel layer, taking Luoyang Metro Line 1 as the engineering background, combined with the actual monitoring data of on-site precipitation, numerical simulation was used to study the seepage characteristics of the pit project precipitation with a suspended water-stop curtain. Through the study, the distribution characteristics of the seepage field under different precipitation depths and aquifer thicknesses were obtained, and the changes in pore water pressure characteristics, flow velocity and water inflow, depending on the precipitation depth and aquifer thickness, were analyzed. The research results show that, when comparing the calculated and measured results of the water level drop in the foundation pit, the average value of the error of the water level drop value in the pit and the descending well is 11.7%, which indicates that the calculation model meets the needs for its use in calculation and analysis. Under the conditions of a suspended water-stop curtain and precipitation, for the pore water pressure characteristics, the variation amplitude of the pore water pressure inside the pit increases with the precipitation depth and aquifer thickness. For the maximum flow velocity, all characteristics are present at the bottom of the suspended water-stop curtain, near the inside of the pit. The maximum flow velocity increases linearly with the precipitation depth and there is a threshold when the aquifer thickness is five times the precipitation depth. For water inflow, it increases with the increase in the precipitation depth and aquifer thickness, but, with a continuous increase in the aquifer thickness, the magnitude of water inflow growth decreases.

Experimental investigation on the hydraulic characteristics of water inrush in deep buried filled karst conduit considering the permeability

Water inrush in karst areas is a challenge for the safe construction of deep-buried tunnels due to complicated hydrogeological environments, especially encounters with karst structures that are filled with water and sediments. To study the hydraulic characteristics and disaster evolution of filling materials in complex filled karst conduit during water inrush, large-scale model experiments of seepage and water inrush of filling materials with different permeabilities in karst conduit were conducted according to the engineering geological background of the Qiyueshan tunnel. The whole process of initial seepage and water inrush caused by excavation under the conditions of high ground stress and high confined water pressure is presented, and the spatio-temporal evolution characteristics of pore water pressure inside karst fillings were deeply analyzed. The results show that the pore water pressure in karst fillings generally increases with time while decreasing with the seepage path at the initial seepage stage, and it could be divided into the discontinuous stage, nonlinear stage, and linear stage along the seepage path over seepage time. Additionally, there are undisturbed area, disturbed area, and water inrush of filling materials in karst conduit at the excavation stage. The permeability of karst fillings has an obvious impact on the development process of pore water pressure, as well as the zone and degree of excavation disturbance. The adjacent hydraulic gradient could more accurately reflect the hydraulic characteristics of the karst fillings along the seepage path than the average hydraulic gradient, and make it possible to observe the formation process of seepage channels. The karst fillings with higher permeability has a looser structure and higher porosity, which would form more potential seepage channels at the seepage stage and be more affected by excavation disturbance. Therefore, it is easier to develop into the dominant seepage channels and result in water inrush. Research results may provide reasonable guidance for water inrush prevention and reduce disaster consequences during tunneling in karst areas.

Response of Step-Like Landslide to Pore-Water Pressure under the Action of Typhoon and Rainstorm

Step-like landslides have been attracting more and more attentions because of their displacement with step-like characteristics. At present, there are few studies about the mechanism of a step-like landslide from the perspective of its response to pore-water pressure. This paper considers the Yaoshan landslide disaster mainly affected by rainfall and groundwater in Anxi County, Quanzhou City, Fujian Province, as an example. Based on an in situ monitoring test, we explored the infiltration pathways of typhoons and rainstorms, the main influencing factors, and characteristics of pore-water pressure and determined the relationship between landslide displacement and pore-water pressure in the study area. The results show the following: (1) the pore-water pressure within the slope varies with fluctuation in groundwater level which is influenced by vertical infiltration of rainwater through the slope surface and dominant channels in the study area. (2) The landslide exactly produces a step-like displacement when the pore-water pressure near the slip surface increases from the minimum point to the maximum and then dissipates to the vicinity of the starting point. (3) The correlation between pore-water pressure change and landslide displacement is revealed, and the empirical formula that can characterize slope displacement generated by increment in per unit of pore-water pressure in unit time has been proposed. This study is crucial as it offers important theoretical and practical significance for the analysis of disaster-causing mechanism and monitoring and early warning of the same type of landslide.

Multiscale nonlinear analysis of failure mechanism of loess-mudstone landslide

The sliding mechanism of loess landslides is unique and complex; a single-scale and linear mechanical model cannot describe their failure process scientifically, thus necessitating a multiscale and nonlinear research idea. In order to monitor and observe the whole failure process of loess landslide more conveniently, a physical model test (2.0 × 0.6 × 1.5 m) is designed to simulate the landslide failure process under rainfall condition. Twelve pore water pressure sensors and twelve soil pressure sensors were arranged in three loess layers, and were used to record the numerical variation characteristics of pore water pressure and soil pressure during the failure process of Landslide physical model. The results show that, the failure process of loess landslides and the data from sensors are very random, making it impossible to use a single-scale or linear mechanical model to analyze their mechanics. However, we can well describe the failure process of loess landslide through the micro, meso, and macro scales. Therefore, the mechanical problems of loess landslides should be analyzed from six aspects, including the liquid bridge, force chain, soil mechanics test, a physical model, real landslides, and tectonic stress. In the future, nonlinear and multiscale research ideas can make loess landslide studies more scientific and effective.

Evaluation on Distribution Characteristics of Pore Water Pressure within Saturated Pavement Structure Based on the Proposed Tire-Fluid-Pavement Coupling Model

To investigate the flow characteristics of pore water in asphalt pavement and the variation law of the pore water pressure under vehicle loading, a novel method based on BA network and quartet structure generation set method was proposed to reconstruct the three-dimensional (3D) pavement model with pores. The permeability coefficient and the gradation curve were adopted to evaluate the reliability and stability of the random growth pavement model. Then, the tire-fluid-pavement coupling model was established with FLUENT 3D based on the fluid Mie–Gruneisen state equation. According to the built fluid-solid coupling model, the pressure-velocity coupled finite volume algorithm was applied to study the distribution of the pore water pressure in asphalt pavement. Results show that the pore water pressure in asphalt pavement decays periodically with time under vehicle loading. For different types of asphalt pavement, the pore water pressure in open-graded friction course (OGFC) pavement is the smallest during the whole process. Moreover, the peak values of the pore water pressure decrease in the order of asphalt concrete (AC) pavement, stone mastic asphalt (SMA) pavement, and OGFC pavement. The maximum negative value of the pore water pressure is generally less than 0.3 times the maximum positive values. As for saturated pavement pores, the pore water pressure is hardly affected by the water film thickness. The positive peak value of the pore water pressure increases on an approximate parabolic curve as the vehicle speed improves gradually, while the negative one remains largely unchanged. The results are expected to help reduce tire hydroplaning risk and provide guidance for the selection of asphalt mixtures of drainage asphalt pavement.

Study on the Variation Rule and Characteristics of Pore Water Pressure in the Failure Process of Saturated Rock

With the development of tunnels and other engineering constructions into the deep strata, rock masses are more prone to dynamic damage such as rock bursts under in situ conditions and excavation disturbances. The pore water in the rock mass will produce pressure changes during this process. According to the relationship between the change of pore water pressure and the development of rock mass damage, the variation rule and precursor characteristics of pore water pressure in the process of rock mass failure can be found. In this paper, through mechanical analysis, the evolution law of pore water pressure during the failure process of saturated rock is obtained. The study found that, in the process of rock failure, the pore water pressure presents three stages of linear growth, transition, and decrease. The rise and fall of pore water pressure are closely related to rock damage and influence each other. Through the observation of pore water pressure during coal mining, it is found that the coseismic effect of pore water pressure is significant. It is proved that there is a close correlation between the evolution of the stress field in the surrounding area of the stope and the change of pore water pressure in the surrounding area under the effect of mining disturbance. During the engineering practice, dynamic monitoring can be carried out on the change of pore water pressure inside the rock mass according to the law, and the precursor information of rock mass instability and failure can be explored.

Investigation on the Responses of Overburden Stress and Water Pressure to Mining under the Reverse Fault

This paper focuses on the responses of overburden stress and pore water pressure in confined aquifer to mining under the Ordovician limestone aquifer and the reverse fault. Taking 32 coal seam mining in the first eastern mining area of Qianyingzi coalmine in China as engineering background, on the basis of the mining hydrogeological and engineering geological model of the study area, a numerical calculation model considering the fluid-solid interaction is established. Simulation results indicate that the variation characteristics of pore water pressure in confined aquifer and overburden stress are affected by both mining effect and geological tectonics and are closely related to the shear failure of the reverse fault plane caused by mining effect and the failure characteristics of the overburden strata in the stope. According to the variation of pore water pressure before and after the roof water inrush, the reduction range of pore water pressure can be used as one of the early warning indicators for water inrush accidents. These new understandings are of reference value to the mining water inrush under the combined action of reverse faults and confined aquifers and to the establishment of corresponding forecasting and early warning systems.

Experimental Study on Undrained Shear Properties of Saline Soil under Freeze-Thaw Cycles

The freeze-thaw cycle is an important external factor affecting the hydromechanical characteristics of saline soil in cold regions. Due to the presence of water and salt, it has a greater impact on stability. The construction of various projects, such as ditch fills and road subgrades, has mostly used disturbed soils. Therefore, this article takes remolded saline soil in Qian’an, Jilin Province, China, as the research object to evaluate the action of freeze-thaw cycles on the critical state line, effective stress path, pore water pressure-strain relationship, stress-strain relationship, shear strength index, and other mechanical properties via a freeze-thaw cycle test and a consolidated undrained triaxial shear test (CU). The experimental results show that regardless of whether the soil specimen undergoes a freeze-thaw cycle, its stress-strain relationship shows characteristics of strain hardening, while, as the number of freeze-thaw cycles increases, the shear strength gradually decreases. As both the confining pressure and number of freeze-thaw cycles increase, the pore water pressure increases, as does the pore water pressure coefficient in shear failure. Under the action of freeze-thaw cycles, on the p ′ − q plane of the stress space, the effective stress path gradually moves to the lower left side. Both the effective stress path and the pore water pressure characteristics indicate that the degree of consolidation of the soil specimens continuously decreases as the number of freeze-thaw cycles increases. The position of the critical state line gradually lowers, and the critical state stress ratio decreases. The effective stress strength index can more accurately reflect the comprehensive influence of freeze-thaw cycles and confining pressure on the mechanical characteristics of soils than the total stress strength index. Logistic functions can be used to fit and predict the degradation law of the internal friction angle and cohesion.

A Simulation Study on the Spatial‐Temporal Characteristics of Pore Water Pressure and Roof Water Inrush in an Aquiclude

As the working face advances, the overlying aquiclude is subjected to periodic dynamic loads, causing pore water pressure distortion, which provides important forewarning for a water inrush disaster in shallow coal seams. In order to analyze the pore water pressure in an aquiclude and determine the spatial‐temporal characteristics of the water inrush, the aquiclude is simplified into a saturated, porous, liquid‐solid medium and a viscoelastic dynamic model is created to obtain the analytical solution of the pressure distribution. FLAC3D is used to develop a fluid‐solid coupling model and to analyze the characteristics of the pressure change and overburden under different mining intensities. This study on pore water pressure in an aquiclude and the determination of the spatial‐temporal characteristics of the water inrush provides a foundation for developing early‐warning systems for roof water inrush.

Experimental study on the mechanical properties of Guiyang red clay considering the meso micro damage mechanism and stress path

This study investigated the macroscopic physical and mechanical properties of Guiyang red clay during surcharge loading, lateral excavation and lateral unloading with axial loading, and clarified the failure mechanism of microstructure before and after shear under different stress paths of CTC, RTC and TC. Consolidated undrained triaxial shear permeability, SEM scanning, XRF fluorescence spectrum analysis and XRD diffraction tests were conducted to simulate the actual engineering conditions. The stress–strain curve, shear strength, pore water pressure variation rule and macroscopic failure mode of soil samples under different stress paths were analysed. In addition, Image Pro Plus 6.0 and PCAS were used to study the relationship between the macro mechanical properties and micro microstructure failure under different stress paths. The stress–strain curves from CTC, RTC and TC in CU tests were different, with the peak values of shear stress under the three stress paths being P-increasing, equal P-path and P-decreasing path. Moreover, the internal friction angle and cohesion of the increasing P path were higher than those of equal P path and decreasing P path, hence, the influence of stress paths on the cohesion is greater than that of internal friction angle. The pore water pressure is strongly dependent on the stress path, and the variation characteristics of pore water pressure are consistent with the change in the law of the stress–strain curve. Under the same confining pressure in the P-increasing path, the shear failure zone runs through the whole soil sample, and the shear failure zone is significant, whereas under the condition of the P-reducing path, the shear failure angle of soil sample is about 65°, 55° and 45°, and in the equal P path, the soil sample is dominated by the confining pressure, with no obvious microcrack on the surface of the soil sample. The difference is that the distribution of pores in the path of increasing P and equal P is directional, and the anisotropy rate is small, while the distribution of pores in soil samples with shear failure and before shear is random and the anisotropy rate is high.

Anti-floatation design test and simulation study of large LNG underground storage tanks

With the changes in China’s energy demand, the proportion of liquefied natural gas (LNG) is expected to account for 10% of the country’s total energy resources by 2020; thus, the demand for large storage tanks has become urgent. However, all LNG storage tanks in China are located aboveground, with no precedent set for fully- or semi-underground storage tank implementation. Therefore, the present study analyzes the displacement and pore water pressure characteristics of underground LNG storage tanks under anti-floatation conditions based on the construction of a 250,000 kL underground storage tank that is 91 m in diameter and 42 m in depth. Centrifuge tests were conducted to explore the development laws of displacement and pore water pressure of the bottom plate under different load conditions for fully- and semi-underground tanks. The displacement response of the tank under the flotage condition clearly exhibited three-stage characteristics, that is, the safe, dangerous, and failure stages. The development laws of each stage were then summarized, analyzed, and explained by numerical and analytical calculations to provide a theoretical basis for storage tank design and anti-floatation monitoring.

Research on rainfall infiltration law and slope stability analysis

Rainfall is an important factor leading to slope landslide. Aiming at the problem of slope stability under rainfall, this paper uses the unsaturated seepage theory to dynamically describe the rainfall infiltration effect, and analyzes the distribution characteristics of pore water pressure of slope soil and the change law of slope water level under the action of rainfall, at the same time, deeply analyzes the law of slope stability changes based on strength reduction algorithm. The results show that: with the passage of rainfall time and the increase of rainfall intensity, the slope infiltration depth gradually increased. At the same time, rainfall increased the groundwater level in the slope, and leaded to increased pore water pressure in the slope soil, and the transient saturation zone gradually formed and expanded, and finally leaded to a significant reduction in slope stability coefficient.

Distribution characteristics of floor pore water pressure based on similarity simulation experiments

To analyse the impact of underground pressure on the variation in floor porosity and pore water pressure distribution during the coal seam mining process, this paper uses closed and open water pressure sensors to analyse rock pressure, water pressure zoning and layer distribution characteristics of the coal seam floor under mining effects based on a simulation analysis method using similar rock materials; the results determine that the separation characteristics of the pore water pressure distribution are affected by the rock pressure ‘barrier’ function, which is caused by changes in rock permeability under the coupling effect. To quantitatively analyse the rock pressure barrier’s impact on the floor mechanical structure, this paper proposes the ‘virtual separation layer’ concept and defines the virtual separation layer index to determine the scope of the floor tension fracture zone. Through monitored data of pore water pressure at different depths of the floor during field mining, the variation between the water pressure, porosity, mining distance and floor depth is obtained; similar material simulation results are verified, and a zonal distribution model of pore water pressure in the floor is established, providing a reference to investigate the distribution of pore water pressure in the floor under mining disturbances. The results show that the influence of changes in mining stress will also lead to a differential distribution of the floor mechanical properties and ultimately damage the floor and affect the inrush of the confined water. The research results play an important role in risk classification and prevention of water pressure distribution in coal seam floors.

Experimental and Numerical Analysis on Hydraulic Characteristics of Coastal Aquifers with Seawall

In this study, hydraulic model experiments were conducted to measure the saltwater–freshwater equilibrium interface in a coastal aquifer with underground obstructions such as an impermeable seawall. To analyse the hydraulic characteristics inside the coastal aquifer, numerical analysis was conducted using a non-hydrostatic Navier-Stokes solver based on the Porous Body Model (PBM), which can directly analyse groundwater flow. A unique saltwater–freshwater equilibrium interface that does not appear in typical coastal aquifer analyses was observed in a sandy tank experiment. In the experiment, the rise of the groundwater level behind the seawall increased the pressure gradient and groundwater flow rate, causing the saltwater–freshwater interface to move towards the sea and a freshwater region to form on the seabed in front of the seawall. The numerical analysis enabled close examination of the groundwater level distribution, groundwater flow, seawater–freshwater interface, and pore water pressure characteristics of the coastal aquifer with underground obstructions. The sandy tank experiment also provided an understanding of the hydraulic characteristics of groundwater in the coastal aquifer with a seawall, which previously could not be accurately analysed. The experimental and analytical results demonstrated that the rise of groundwater level due to underground obstructions in the coastal aquifer increased the pressure gradient and groundwater flow rate and slowed seawater intrusion. This principle can be employed to sufficiently reduce seawater intrusion of coastal aquifers.

Thermodynamic responses of a crushed-rock interlayer embankment on sloping permafrost ground under traffic loads

Crushed-rock embankments (CRE) are widely used engineering structures in permafrost regions, and they can effectively prevent the underlying permafrost from thawing. The heat transfer mechanisms of CREs have been extensively investigated using experimental and numerical methods, but the associated mechanical behavior has been largely ignored. However, the safe operation of an embankment is controlled not only the thermal state but also the mechanical stability and deformation. To comprehensively evaluate the thermomechanical behavior of the CREs in permafrost regions, we build a thermodynamic model of a CRE based on three conservation principles and select a crushed-rock interlayer embankment (CRIE) on sloping permafrost ground to simulate the traffic load-induced responses over four typical seasons in its 20th service year. The numerical results show that the CRIE can actively cool the underlying permafrost, but the CRIE temperature exhibits obviously seasonal differences. Thus its mechanical behaviors are seasonally different. By comparing the acceleration, velocity, displacement and excess pore water pressure characteristics of the CRIE, their amplitudes are the smallest on April 15 and the largest on October 15 in a year. So October 15 is the most unfavorable time, in which the dynamic responses to traffic loads are the most extensive. When the traffic load leaves the CRIE, the residual displacements extrude outward and downward from the centerline of the embankment surface, and the downside part of the embankment moves along the ground slope. Similarly, the residual displacement is higher on October 15 in a year. Therefore, engineers should pay close attention to the most easily damaged zone in the most unfavorable time. Through this study, we hope the numerical model and conclusions of the study can provide theoretical support for CRIE construction and maintenance and a reference for future studies of CREs in permafrost regions.

The response of pore water pressure to snow accumulation on a low-permeability clay landslide

A snowpack is known to affect landslide stability as the snow loading changes. Furthermore, the snowpack can have effects on the hydrological behavior in the landslide mass. To clarify the response of pore water pressure to snow loading, continuous field-based monitoring of hydraulic and meteorological factors in landslides was conducted for a deposit of extremely low-permeability “quick clay” in Mid-Norway. The pore water pressure increased during every snow-covered period. The pressure exhibited little response to meltwater and/or rain, but corresponded closely to changes in snow accumulation. The increase in pore water pressure during the snow-covered period was considered to be excess pore water pressure generated by undrained snow loading on the extremely low-permeability quick clay. The pore water pressure displayed a positive linear relation with the snow load, and the ratio of the increase in the pore water pressure to the snow load (rusnow) was 0.49–0.53. These values show that approximately half of the snow load contributed to the excess pore water pressure. Continuous field-based monitoring was also conducted for another landslide in relatively high-permeability deposits in Japan, where the pore water pressure showed a relatively low rusnow of about 0.15 and a different timing of the pressure peak. This comparative result indicates that the response characteristics of pore water pressure to the snow loading are strongly affected by the permeability of the landslide mass. Although the excess pore water pressure generated by the snow load theoretically had a negative effect on the slope stability, the value of excess pore water pressure at the monitored landslide was relatively too small to affect its stability.