Increase In Pore Water Pressure Research Articles

Evaluation of techniques for mitigating snowmelt infiltration-induced landsliding in a highway embankment

Infiltration-induced landslides threaten transportation infrastructure around the world, and impose both direct costs through repair and remediation work and indirect costs through lost economic activity. Therefore, finding the most cost-effective techniques to mitigate slope failures that can impact critical infrastructure links is desirable. The Straight Creek landslide, which affects a segment of Interstate 70 in Summit County, Colorado (USA), has experienced seasonal failure driven by rapid springtime snowmelt infiltration since the early 1970s, allowing changes in its stability to be studied. Past studies have established that seasonal failure is driven by pore-water pressure increase caused by the rapid infiltration of snowmelt and the hydraulic conductivity contrast between upper slope materials and the highway embankment. Two remediation designs have been applied to the site, including lightweight caissons beneath the highway surface in 2011 and 2012, and horizontal drains near the slide toe in 2012. The effects of the lightweight caissons and horizontal drains, as well as an alternative drain design that would extend into the hillslope above the highway embankment, are evaluated within a rigorous hydro-mechanical simulation framework along with a method to generate a field of local factor of safety. Model results show that the effect of the lightweight caissons on the factor of safety is no more than 1% during times of critical instability, as they do not affect the seasonal changes in hydrology that cause destabilizing decreases in effective stress along the failure surface. Horizontal drains are intended to reduce pore-water pressures, but the location of existing drains limit their efficacy due to the low hydraulic conductivity of subsurface materials underneath the highway. Model results indicate that these drains are only partially responsible for a reduction in movement rate since their installation, which is also due to lower annual cumulative snowmelt infiltration levels since 2012. Results also show that an alternative drain design could result in increased stability during critical periods by intercepting downslope subsurface flow before it arrives at the hydraulic conductivity contrast at the embankment.

A catastrophic flowslide that overrides a liquefied substrate: the 1983 Saleshan landslide in China

AbstractFlowslides that override a liquefied substrate can vastly enhance a disaster after failure initiation. These effects may result from the rapid velocity and long runout distance from slides mobilized into flows. It is thus crucial to provide an improved understanding of the transformation mechanisms of catastrophic flowslides for hazard evaluation. This study examines the Saleshan landslide in Gansu, China, which occurred in 1983 and killed more than 200 people. The Saleshan landslide travelled for approximately 1 km due to pore water pressure generation resulting from overrunning and liquefication of the alluvial sands in the river valley below. We used geomorphologic and topographic maps to determine its dynamic features and mobilization behaviors on the landslide body, and placemarks and seismic signals to identify its approximate velocity at different sites. Electrical resistivity tomography (ERT) surveys also revealed the hydrogeological conditions post‐landslide, showing a clear groundwater table along with the liquefied alluvial sand and gravel layers. Particle size distributions and triaxial shear behaviors confirmed more ready liquefaction of superficial loess and underlying alluvial sand in comparison with the red soil above and below them. Novel loading impact triaxial testing was also performed on the alluvial sand to elucidate its liquefaction potential in undrained and drained conditions. The alluvial sand was found to be markedly prone to liquefaction in undrained conditions due to impact‐induced increased pore water pressure. The results further demonstrated that the Saleshan landslide underwent a transformation from a slowing slide on a steep slope, where it originated, to flow on a nearly flat terrace with abundant groundwater that it overrode. The transformation mechanism involved the liquefied alluvium sand substrate, which greatly enhanced the landslide mobility. Along with recent, similar findings from landslides globally, substrate liquefaction may result in a widespread, significant increase in landslide mobility and thus hazard, and the present study identifies the requisite conditions for this phenomenon to occur.

A shaking table-based experimental study of seismic response of shield-enlarge-dig type's underground subway station in liquefiable ground

In instances where earthquakes with large magnitude occur, liquefaction-induced lateral deformation of ground has caused thorough destruction to the underground structure of urban rail transit. A sequence of shaking table experiments was conducted on shield-enlarge-dig type's subway station structure in liquefiable ground exposed to the near field earthquake and the far field earthquake. Outcomes of these experiments are discussed in items of foundation deformation, pore water pressure, acceleration response, dynamic soil pressure, and macroscopic failure of model structure. The measured data infers that, when subjected to a high intensity earthquake, the model structure generates an upward movement relative to the foundation. The difference between the soil pressure above and below the structure is the internal cause of the liquefaction-induced uplift of the structure. The shear deformation to the soil layer of the foundation happened, and the displacement peak values of the left and right pendula were asymmetric. The acceleration response and its amplification coefficient in the model foundation gradually increases towards the surface from the bottom as a result of a low intensity earthquake, but for medium and high intensity earthquakes, the acceleration response decreases first and then increases. A notable phenomenon of high frequency filtering and low frequency amplification ensued during the seismic wave propagation from the bottom to the surface of soil. For the same depth of measuring points in foundation soil, the time when the pore-pressure ratio reaches the peak lags behind the time when the acceleration reaches the peak, and the hysteresis is more intense with a rise in magnitude of ground movement. The response spectrum of a low intensity earthquake is characterized by low period accumulation and amplification, while the response spectrum of medium and high intensity is characterized by moves from short period to long period and multi-peaks. The pore pressure accumulation of the model foundation experienced a change process of “rapid growth and slow dissipation,” and the time period of its sharp increase was consistent with that of the sharp increase of the acceleration arias strength. The existence of the underground structure notably inhibits an increase in pore water pressure. The earthquake damage mechanism of the underground subway station of shield-enlarge-dig type in liquefiable ground occurred in three phases: shear failure occurred on the column and damaged the opening position and spandrel of the tunnel; connection parts of the side wall and roof exhibited tensile damage; and the underground structure collapsed.

Hydrological control of soil thickness spatial variability on the initiation of rainfall-induced shallow landslides using a three-dimensional model

Thickness and stratigraphic settings of soils covering slopes potentially control susceptibility to initiation of rainfall-induced shallow landslides due to their local effect on slope hydrological response. Notwithstanding the relevance of the assessment of hazard to shallow landsliding at a distributed scale by approaches based on a coupled modelling of slope hydrological response and slope stability, the spatial variability of soil thickness and stratigraphic settings are factors poorly considered in the literature. Under these premises, this paper advances the well-known case study of rainfall-induced shallow landslides involving ash-fall pyroclastic soils covering the peri-Vesuvian mountains (Campania, southern Italy). In such a unique geomorphological setting, the soil covering is formed by alternating loose ash-fall pyroclastic deposits and paleosols, with high contrasts in hydraulic conductivity and total thickness decreasing as the slope angle increases, thus leading to the establishment of lateral flow and an increase of pore water pressure in localised sectors of the slope where soil horizon thickness is less. In particular, we investigate the effects, on hillslope hydrological regime and slope stability, of irregular bedrock topography, spatial variability of soil thickness and vertical hydraulic heterogeneity of soil horizons, by using a coupled three-dimensional hydrological and a probabilistic infinite slope stability model. The modelling is applied on a sample mountain catchment, located on Sarno Mountains (Campania, southern Italy), and calibrated using physics-based rainfall thresholds derived from the literature. The results obtained under five simulated constant rainfall intensities (2.5, 5, 10, 20 and 40 mm h−1) show an increase of soil pressure head and major failure probability corresponding to stratigraphic and morphological discontinuities, where a soil thickness reduction occurs. The outcomes obtained from modelling match the hypothesis of the formation of lateral throughflow due to the effect of intense rainfall, which leads to the increase of soil water pressure head and water content, up to values of near-saturation, in narrow zones of the slope, such as those of downslope reduction of total soil thickness and pinching out of soil horizons. The approach proposed can be conceived as a further advance in the comprehension of slope hydrological processes at a detailed scale and their effects on slope stability under given rainfall and antecedent soil hydrological conditions, therefore in predicting the most susceptible areas to initiation of rainfall-induced shallow landslides and the related I-D rainfall thresholds. Results obtained demonstrate the occurrence of a slope hydrological response depending on the spatial variability of soil thickness and leading to focus slope instability in specific slope sectors. The approach proposed is conceived to be potentially exportable to other slope environments for which a spatial modelling of soil thickness would be possible.

The critical mechanics of the initiation of loess flow failure and implications for landslides

Abstract An essential hypothesis is that the flow failure landslides occurring in the Chinese Loess Plateau may initiate in the high-moisture-content loess in the capillary zone rather than in the saturated zone within the slope. Two effective stress paths, namely, the monotonically increasing loading and wetting-based constant loading under undrained conditions, are performed on intact and mechanically compacted loess, aiming at specifying their hydromechanical trajectories when subjected to an increasing water content. The results indicate that static liquefaction is initiated when the soil moisture reaches a threshold during the wetting process after exhibiting a sharp increase in pore water pressure accompanied by strain-softening behavior. Accordingly, we define this state as the initiation of flow failure under the unsaturated framework to distinguish it from static liquefaction, and first propose its corresponding critical mechanics and criterion. Its validity and physical justification are mainly evidenced by the following observations: i) Significant difference in the pore characteristics of the test samples before and after flow failure initiation; ii) Approximate equivalence between the measured and predicted hydromechanical thresholds at the flow failure initiation state; iii) Existence of the strength envelope corresponding to the flow failure initiation state; and iv) The uniqueness of the modified critical state line in the full suction range. This paper provides a general approach to accurately identify the flow failure potential for unsaturated loess, especially in the capillarity zone within a slope, which is of vital importance to the early identification and risk mitigation of loess landslides with a fluidization pattern.

Effective stress and pore water dynamics in unsaturated soils: Influence of soil compaction history and soil properties

Effective stress is an important strength indicator for understanding and fundamentally predicting soil behaviour due to mechanical disturbance. This study investigated the influence of `soil properties on effective stress in relation to matric potential, and soil sampling direction (vertical/horizontal). Undisturbed soil samples representing 3 different locations were collected at 4 depths and in 2 sampling directions, to determine which soil properties mostly affect the effective stress in response to the magnitude of the stress applied. The soil properties included texture, organic carbon content, dry bulk density, void ratio, pre-compression stress and prevailing matric potential. The results showed that both the effective stress and the concomitant changes in pore water pressure largely depend on the prevailing matric potential in the soil. In addition, changes in soil structure caused by subsurface soil compaction as a result of tillage, organic carbon and clay content influenced the magnitude of the effective stress and pore water pressure in soils during loading. The porewater pressure measured under static loading is sampling direction dependent due to differences in hydraulic conductivity and pore continuity. Porewater pressure increases (become less negative) with increases in the fraction of fine pores in the soil while it may either remain constant or decrease, when the medium and coarse pore fractions in the soil increases. This implies that the smaller the pore connectivity and continuity, the less negative the changes in pore water pressure become. Also, the higher the pre-compression stress (sometimes due to higher organic carbon content), the more consistent the applied stress induced an increase in the calculated effective stress.

Exploring the possibility of assessing the damage degree of liquefaction based only on seismic records by artificial neural networks

This study presents a new approach to determine the damage degree of liquefaction caused by a large earthquake. We propose an artificial neural network (ANN) model based only on the seismic records of ground and define the degree of liquefaction “DDL” as a damage index. This ANN model predicts the degree of excess pore water pressure increase as the correct output label based on the seismic records obtained from the three-dimensional shaking table test. The proposed model achieved high accuracy, and the outcomes from training data indicated that the ANN model is suitable to function as a liquefaction assessment system. Further, to evaluate the applicability of the proposed ANN model in the real world, the datasets of waves from three actual seismic records were input to the ANN as validation data. The DDL judgment obtained was a good fit with the real phenomena observed.

Grain Configuration Effect on Pore Water Pressure in Debris Flow

The generation and development of excess pore water pressure directly affects the grain interaction in debris flow, which can significantly reduce the friction strength and promote the movement of debris flow. It has been found that coarse grains favor the increase in excess pore water pressure, but the effect due to grain configuration is missing in studies. In order to study the influence of grain configuration, field investigations and laboratory tests were carried out for two typical cases, i.e., flow with coarse grains evenly mixed (case I) and flow with coarse grains floating on the surface (case II). The results show that case II generates much higher excess pore water pressure than case I. The variation of relative excess pore water pressure (Ur) with time (t) satisfies the power function relationship: Ur = mt–n. Case II often has a smaller n value, meaning a low dissipation rate of excess pore water pressure. This study is helpful for a better understanding of granular effects in debris flow.

Railway embankment behaviour due to increased axle loads - A numerical study

Due to an increase in axle loads, the development of excess pore water pressure and settlement in a railway track foundation of fine-grained subgrade soil can be observed. A thorough understanding of the mechanism of development of excess pore water pressure is essential for understanding the development of settlements and the design of potential ground improvement. In this paper, a three dimensional numerical study is presented, which investigates the effects of an increase in axle loads of trains on both excess pore water pressure and settlement. Special attention is given to a soft soil layer beneath the embankment and the influence of ground improvement (deep soil mixing columns). As a result, an increase in axle loads leads to a considerable increase in both excess pore pressures and settlement in the subgrade layer. This increase is more significant in the case of heavy axle load (32.5 tons) than that of the light axle load (16 tons). In addition, cyclic loading can lead to a considerable increase in both vertical displacements and excess pore water pressure. The use of deep soil mixing columns reduces excess pore water pressures and settlements significantly.

Shaking table tests to investigate the influence of grain shape on tnb he excess pore water pressure

Liquefaction that occurred in the Palu city in 2018 is the most devastating natural phenomena. The liquefaction phenomenon is a condition in which a saturated soil loses its strength due to an earthquake. This study aims to determine the increase in excess pore water pressure in solid particles and void particles after they are subjected to earthquake loading. Testing is done by shaking the table. Earthquake loads are modeled with cyclic loads, which are sine waves with acceleration amplitudes of 0.35g and 0.38g. The results showed that liquefaction conditions had not yet occurred in cyclic load applications with an acceleration amplitude of 0.35g and a time duration of 7s. At an acceleration amplitude of 0.38g with a time duration of 60 s, the sand model underwent liquefaction at 7s after the test began. Analysis of the results of transducer records installed at a distance of 0.10 m from the surface of the test model shows that the addition of pumice by 10%, 30%, and 50% can reduce pore pressures by 15%, 62%, and 85%, respectively.

Fluctuation Effect of Reservoir Water Level on the Seepage of Earth-Fill Dam

Lots of dam failures are the result of uncontrolled seepage. The collapse of the Situ Gintung Dam in Tangerang, Banten-Indonesia in 2009 due to heavy rains caused the dam structure to collapse. This is due to increased pore water pressure in the landfill. To anticipate collapse due to uncontrolled seepage, it is necessary to monitor it based on the behavior of changes in rainfall and reservoir water levels. Seepage within the dam body is often monitored using instrumentation tools such as standpipe piezometer (standpipe piezometer) or electric piezometer. But often the piezometer cannot work properly because it is clogged, so it cannot monitor the condition of the seepage. Other instrumentations such as V-Notch are also used to measure seepage discharge. This study aims to determine the behavior of changes in the reservoir water level caused by changes in rainfall and its effect on body seepage of the earth-fill Type dam. By knowing the phenomenon of the behavior of the relationship between reservoir water infiltration and rainfall, it will obtain information on rainfall that endangers the dam which will affect the downstream. In this study, a case study of the Selorejo Dam was taken which has a large enough reservoir capacity of about 31 million m3 which is included in the Brantas River Basin. The results showed that 5 piezometers devices were damaged (SL 1, SL 2, SL 4, SL 6, and SL 7) where they could not read the phreatic water level properly, and 2 piezometers were less sensitive to reading fluctuations in reservoir water levels. namely SL 10 and SL 11 which showed R2 values of 29.78% and 39.4%, respectively. While the maximum seepage discharge is recorded at 1474 liters/minute, this is still below the critical discharge of 1630 liters/minute allowed for this dam, but this needs to be a concern, especially the discharge from toe drain from the left side seepage and C-area which is the leakage from the left support pedestal also contributes a larger discharge than other observation points.

Laboratory full-scale model test of subgrade mud pumping for ballastless track of high-speed railway

ABSTRACT This paper aims to clarify the mechanisms and driving factors of subgrade mud pumping for ballastless track in high-speed railway. A full-scale model test system in which the train dynamic loading and rainfall condition could be simulated was developed, allowing the recurrence of subgrade mud pumping. The relationship between the degree of mud pumping and the hydrodynamic pressure characteristics of subgrade was investigated, and the mechanisms and driving factors of mud pumping were also clarified. It was shown that the subgrade surface layer under the cracked concrete base was always saturated under the condition of rainwater infiltration, and it was prone to mud pumping given a long-term action of the dynamic loading of trains. A significant increase in excess pore water pressure to a certain extent mobilized the mud pumping. Accordingly, the prevention and treatment of mud pumping can be the prevention of rainwater infiltration or more efficient drainage.

Landslide mechanism of waste rock dump on a soft gently dipping foundation: a case study in China

In Miyi County of Sichuan Province of China, landslides are the most common type of waste dump failure, resulting from poorly compacted waste rock dump on weak soil. A waste dump failure on a soft, gently dipping foundation is examined in terms of the geological conditions, failure characteristics, movement processes and deposit forms, including the long run-out feature of the landslide. The waste dump failure and the subsequent deformation to the foundation are caused by an increase in pore water pressure and developed through the soft foundation underlying the heavy waste. The landslide run-out distance is influenced by the liquefiable silty clay layer. In this study, the landslide was triggered by the heavy load of waste rocks on top of a soft foundation of low-bearing capacity. The increased pore pressure in the foundation could not be released, which caused deformation of the foundation and triggered a landslide. The stability evolution is also researched in this study. In this study area: (1) the landslide mass is accelerated by the liquefaction of the saturated and water-rich silty clay layer, and the plastic deformation of the foundation caused by the collapsed waste dump; (2) the shear strength is strongly influenced by the water content; (3) when a waste dump is constructed on top of a water-sensitive gently dipping ground, it is important to provide drainage to dissipate pore water pressure; and (4) considering low factors of safety during heavy rains, secondary landslide is possible in the event of heavy rain and earthquake, indicating that heavy rainfall is the leading cause of the waste dump failure.

Methodology to Characterize the Seismic Compression of Unsaturated Sands under Different Drainage Conditions

Abstract This study focuses on a new experimental setup and methodology to characterize the volumetric contraction of unsaturated sands during cyclic shearing under different drainage conditions. A new cyclic simple shear device was developed with suction-saturation control using a hanging column suitable for testing unsaturated granular soils with a maximum suction of 11 kPa. The pore water and pore air pressures are monitored during cyclic shearing using an embedded tensiometer and a gauge pressure transducer protected by a hydrophobic filter, respectively. In addition to describing the specimen preparation techniques and testing methodology, typical results for the seismic compression of nearly saturated, dry, and unsaturated sand specimens during cyclic shearing under different drainage conditions are compared. The differences in the response of these sand specimens were interpreted using the changes in mean effective stress and secant shear modulus during cyclic shearing. In drained conditions, the unsaturated sand specimen showed lower seismic compressions than the dry sand specimen and the nearly saturated sand specimen. In undrained conditions, a greater contraction was observed for the unsaturated conditions due to decreases in mean effective stress and secant shear modulus. The decrease in effective stress occurred due to a decrease in matric suction associated with different rates of increase in pore water and air pressure and an increase in degree of saturation with volumetric contraction.

Cyclic Secant Shear Modulus and Pore Water Pressure Change in Sands at Small Cyclic Strains

AbstractWhen fully saturated sandy soil is subjected to cyclic straining in undrained conditions, pore water pressure increases and effective stress decreases. Therefore, it has been assumed that i...

A New Unified Solution for Deep Tunnels in Water-Rich Areas considering Pore Water Pressure

Pore water pressure has an important influence on the stresses and deformation of the surrounding rock of deep tunnels in water-rich areas. In this study, a mechanical model for deep tunnels subjected to a nonuniform stress field in water-rich areas is developed. Considering the pore water pressure, a new unified solution for the stresses, postpeak zone radii, and surface displacement is derived based on a strain-softening model and the Mogi-Coulomb criterion. Through a case study, the effects of pore water pressure, intermediate principal stress, and residual cohesion on the stress distribution, postpeak zone radii, and surface displacement are also discussed. Results show that the tangential stresses are always larger than the radial stress. The radial stress presents a gradually increasing trend, while the tangential stress presents a trend of first increasing and then decreasing, and the maximum tangential stress appears at the interface between the elastic and plastic zones. As the pore water pressure increases, the postpeak zone radii and surface displacement increase. Because of the neglect of the intermediate principal stress in the Mohr-Coulomb criterion, the postpeak zone radii, surface displacement, and maximum tangential stress solved by the Mohr-Coulomb criterion are all larger than those solved by the Mogi-Coulomb criterion. Tunnels surrounded by rock masses with a higher residual cohesion experience lower postpeak zone radii and surface displacement. Data presented in this study provide an important theoretical basis for supporting the tunnels in water-rich areas.

Instability of Unsaturated Soils Under Constant Deviatoric Stress in Drained Conditions

The paper presents the results of an experimental investigation to study the instability of unsaturated slopes under constant deviatoric stress in drained conditions. The experimental program included compression triaxial tests on specimens prepared with various degree of compactions, i.e., 68%, 76%, and 83% and subjected to net confining stresses of 30, 50 and 90 kPa. During shear process, the specimens were first sheared in constant water content conditions to the pre-defined value of deviatoric stress (i.e., 25% of qmax). The pre-defined deviatoric stress on specimens was then kept constant, and matric suction was decreased by increasing pore water pressure to start water infiltration. After completed water infiltration, the specimens were sheared again in constant water content conditions. The results showed that the behavior of soil is affected significantly by variation in the degree of compaction and confining stress when subjected to water infiltration. Very loose soil with low net confining stress showed large collapse deformation. Finally, it was also observed that the gradient of the failure line is increased from 1.08 to 1.32 with an increase in the degree of compaction, hence increasing the stability of slopes.

Assessment of Stabilized Silt Clay Sand with Oil Palm Fibre Bunch (OPFB) Local Fibre for Slope Foundations: A Case of Coastal Soils of Mombasa, Kenya

Improvement of shear strength parameters is essential for designing the OPFB fiber mix with silt clay sand for slope stability. The objective of this study was to assess the stabilized silt clay with oil palm fibre bunch (OPFB) local fibre for slope foundation. Series of laboratory tests were conducted on various materials under study and the results revealed that, OPFB mix can be used as an additive to cement for purpose of improving engineering properties of the Silt Clay sand to cut down costs without compromising the set standards. It was established that, the shear strength parameters of the soil-fibre mixture (φ and C) can be improved significantly up to an optimum and reach a certain point where it starts to decline. The shear stress–strain curves obtained from the CU triaxial tests for reinforced sands with 30 mm fibre length together with those for unreinforced silty sand were compared; the result indicated that, fibre-reinforced specimen showed higher deviator stress at 0.25% fibre and reduces at 0.5% fibre. The strain corresponding to the peak deviator stress was increased by fibre content. Patterns of stress–strain curves for all reinforcedsamples indicated improvement in the deviator stress for all compositions and fibre content. Deviator stress of fibre-reinforced soil showed a slight increase with increasing pore pressure. The increase of the fibre content caused an increase in pore water pressure due to inclination of specimens to decrease the volume. Changes in the shear strength of fibre-reinforced soil indicated that soil strength parameters (internal friction angle φ’ and cohesion C’) increase as the internal friction surface increases between fibre and soil at certain point.

Mechanical properties and acoustic emission characteristics of granite under thermo-hydro-mechanical coupling

Exploring the mechanical properties and thermal cracking characteristics of rock under thermo-hydro-mechanical coupling in detail is of great importance for the safe excavation and stability of deep rock engineering. The mechanical properties and thermal cracking characteristics of granite under burial depths of 1000 m (confining pressure of 25 MPa) and 1600 m (confining pressure of 40 MPa) at a temperature of 110?C and a pore water pressure of 10 MPa were studied. The results show that the elastic modulus decreases with increasing temperature under a confining pressure of 25 MPa, whereas under a confining pressure of 40 MPa, the elastic modulus increases with increasing temperature. As the pore water pressure increases, the elastic modulus decreases slightly. Poisson?s ratio increas?es with increasing temperature below 40?C but decreases from 50-110?C. Pois?son?s ratio increases as pore water pressure increases. During the heating process, acoustic emission activity is first detected at 30-40?C and is relatively stable from 40-90?C. The acoustic emission activity increases sharply at 90-110?C, and the thermal cracking threshold of granite under thermo-hydro-mechanical coupling is approximately 95?C.

Geomechanical characterisation and dynamic numerical modelling of two anthropogenic fill slopes

In the last 22 years, four large (between approximately 1000 and 5000 m3) flowslides in anthropogenic fill materials have occurred in residential areas of the greater Wellington region, New Zealand. Such failures are relatively rare, given that there are over 1600 mapped fill bodies, formed between the early 1900s and present day within the region. Nonetheless, their performance under strong earthquake shaking has yet to be tested, given no strong ground motions (>0.15 g) have shaken the region since their construction. In this study, we used remote sensing techniques, borehole investigations, geotechnical testing and numerical modelling to investigate two fill bodies that are characteristic of those constructed across the Wellington region. This paper presents the results from the dynamic analysis of these two sites under strong earthquake shaking.The maximum anthropogenic fill thicknesses at both sites ranged between 20 m and 30 m. The fills tested varied from sandy gravel with some silt to clayey gravelly silt sand (D50 from 0.02 mm to 10 mm and D90 from 5 mm to 50 mm). Based on the field mapping, site investigation and laboratory results, two-dimensional geotechnical cross-sections of the sites were generated and used as the basis for the numerical simulations. Accelerograms recorded from eleven local and overseas earthquakes were used as inputs for the modelling. These were selected and scaled to simulate the amplitude and frequency content of the different types of earthquake shaking that could affect the sites up to 2.5 g, which represents a peak ground acceleration with an approximate annual exceedance probability of 0.00005. The results indicate simulated permanent ground displacements, due to sliding of the fill in the range of 0.01 m to >10 m, with the amount of displacement increasing with increasing Peak Ground Acceleration (PGA). Although at small displacements it is unlikely the fill slopes would fail catastrophically to form flowslides, the simulated permanent displacements are large enough for an earthquake with a free field PGA of >0.6 g (annual exceedance probability (AEP) of 0.002) to potentially disrupt buried elastic pipe utilities (especially the water pipes). Such deformation could lead to the leakage of water from broken pipes, and an increase in pore-water pressure within the fills, which could in turn lead to the development of post-earthquake flowslides. After a major earthquake, such cascading hazards may pose a major problem for recovery activities.