Dissipation Of Pore Water Pressure Research Articles

Semi-numerical analysis of negative skin friction on permeable pile due to consolidation induced by piling

A semi-numerical approach is proposed to estimate the dissipation of excess pore water pressure and the development of negative skin friction at the normal impervious pile and the permeable pile after piling. An impeded drainage boundary associated with the opening ratio and opening size is introduced to simulate the drainage condition at the soil-permeable pile interface. In the proposed mathematical framework, analytical approaches are adopted to solve the linear equations, and numerical techniques are utilized to address the nonlinear problems so that the adaptivity and efficiency of the mathematical framework can be well balanced. Through comparisons with the field tests, the model tests, and the theoretical answers, the correctness and rationality of the proposed method are validated. Through a parametric study, the key design parameters of the permeable pile are investigated, and the following design tips are obtained: 1. The opening ratio plays the most important role in the drainage efficiency of the permeable pile; 2. Increasing the number of openings is preferred rather than increasing the size of openings, especially when the opening ratio is determined.

Finite-difference solution for dissipation of excess pore water pressure within liquefied soil stabilized by stone columns with consideration of coupled radial-vertical seepage

The implementation of stone columns is a widely accepted method for improving the stability of liquefiable soil. A comprehensive understanding of the behavior of the composite ground is crucial for accurate design and calculation in practical applications. Several existing mathematical models were established to assess characteristics of the stone column-improved ground by typically ignoring the vertical seepage within liquefiable soil. This negligence will inevitably lead to significant calculation errors, particularly when the vertical permeability of liquefiable sites is high or the installation spacing of stone columns is large. In this context, a new mathematical model which accounts for coupled radial-vertical seepage within liquefiable soil is proposed to determine the reinforcement performance of stone columns. The equal strain assumption and new boundary conditions are incorporated to obtain numerical solutions with the finite difference method. Then the present solution is degenerated to the conventional calculation model to verify the reasonability of the proposed model. Finally, a parametric analysis is conducted to investigate the impacts of crucial parameters on the performance of stone columns for excess pore water pressure variation during soil liquefaction. The results reveal that the peak value of the maximum excess pore water pressure ratio increases with the increment of both the column spacing and cyclic stress ratio. Moreover, the increasing radial and vertical consolidation parameters Tb and Th will accelerate the dissipation rate of the excess pore water pressure of liquefiable sites. Furthermore, the conventional model neglecting the vertical seepage will underestimate the variation rate of the excess pore water pressure, and the calculation error will become larger with the increase of Th.

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.

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.

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.

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.

Modelling biogeochemical clogging affecting piezometers in acid sulfate soil terrain

This study offers an analytical solution for radial consolidation that captures the biogeochemical clogging effect in acid sulfate soils. Field sites and personal communication with industry practitioners have provided evidence of piezometers exhibiting retarded pore pressure readings that do not follow conventional soil consolidation and seepage principles when installed in coastal acidic floodplains. This retarded response together with a variation in pH, ion concentrations, and piezometric heads provided evidence of clogging at and around the piezometers. This paper uses the proposed biogeochemical clogging model, which is an analytically derived system of equations to estimate the excess pore water pressure dissipation of piezometers installed in clogging-prone acid sulfate soils. The inclusion of the total porosity reduction attributed to biological and geochemical clogging improves the predictions of the retarded dissipation of excess pore pressure, especially after about 1 year. This method is validated for two previously identified acidic field sites in coastal Australia, where piezometers measured a very slow rate of dissipation. It is concluded that this model has potential to accurately monitor the performance of critical infrastructure, such as dams and embankment foundations built on acidic terrain.

EFFECT OF CHANGE IN THE COEFFICIENT OF PERMEABILITY ON CONSOLIDATION CHARACTERISTICS OF CLAYS

The settlement rate and pore water pressure dissipation rate are mainly controlled by the permeability of soil. Both laboratory and field tests show that the permeability is varied during the loading and consolidation process. It is known that consolidation process is accompanied by decrease in void ratio which leads to decrease in the coefficient of permeability. The importance of the decrease of the coefficient of permeability on the time rate of settlement and pore water pressure needs to be investigated.This paper takes into account the change in coefficient of permeability during consolidation and studies its effect on consolidation characteristics of a clay layer. The finite element method is used in the analysis and the package Geo-Slope is adopted through coupling the programs SIGMA/W and SEEP/W. The relationship between the applied pressure and permeability was determined experimentally for three samples.It was concluded that the effect of permeability is clear at later times of consolidation due to decrease in void ratio and hence slower dissipation of pore water pressure. Taking into account variable permeability leads to longer times of consolidation. At later times (after 400 days), the excess pore water pressure predicted for the case of variable permeability is greater thanconventional case by about (10 – 12) %.

Influence of water content on clay deformation characteristics subjected to periodic intermittent loading

The influence of clay's drainage and reconsolidation behavior during the intermittent period on clay's deformation needs to be further studied. Dynamic loads, such as traffic and earthquake, etc., have a certain intermittent period during the loading process. This study examined the deformation behavior of the clay obtained from Nanchang under various cyclic stress ratios (CSR) and water content conditions. The results demonstrated that minor strain rebound occurs in all intermittent periods. Aside from that, drainage reconsolidation during intermittent periods alters the pattern of strain accumulation during subsequent loading periods, and cyclic stress levels and water content conditions can impact the intermittent effects. In contrast, the development of strain in the samples under intermittent loading is more negatively impacted by high CSR and low water content (deviation from optimal water content). The hysteresis curve continued to change throughout the test, the accumulation and dissipation of excess pore water pressure changed, and it was found that the samples' resilient modulus had increased, indicating an improvement in the samples' resistance to deformation.

Liquefaction Mitigation Analysis Using Vertical Drain

Liquefaction in semi-permeable soils such as fine sands occurs when the required time to transfer the pore water pressure into the form of effective stress is longer than the increased time of pore water pressure. Therefore, liquefaction mitigation needs to be done to speed up the air pressure flow time during an earthquake such as using vertical drains in this study. The data used here are adopted from previous studies that have been taken from a field test in Air Tawar, Padang. The results showed there is liquefaction potential based on soil data processing. The equivalent circle diameter value for the vertical drain is 1.2 m or a radial equivalent value of 0.6 m. Based on the analysis, the 60% pore water pressure dissipation within 20 seconds was obtained at a distance of 0.291 m in the radial direction. From the data above, it can be obtained that the vertical drain is capable of dissipating 60% of water pressure within 20 seconds to avoid liquefaction within the soil mass. Then it can be concluded that the application of vertical drain at a certain distance and depth can mitigate liquefaction in soil layers.

Set-up effect of large-diameter open-ended thin-walled pipe piles driven in clay

A finite element method (FEM) model was developed to investigate the distribution and dissipation of the soil excess pore water pressure (EPWP) around large-diameter open-ended thin-wall steel pipe piles (LOTPs) driven by impact loads into saturated clay, in addition to the set-up effect of LOTPs. The initial pore water pressure (PWP) distribution and vertical bearing capacity of LOTPs after EPWP dissipation were analyzed through this numerical model. The EPWP mapped onto the FEM model was compared with previously reported distribution curves, revealing that the numerical results were generally similar to those of previous theoretical models. Following dissipation for 28 days, the load–settlement curves of LOTPs were compared with the results of several specifications; this indicated that the larger the LOTP diameter, the greater the similarity between axial bearing capacities calculated via the FEM model and the specifications. This FEM model could generally satisfy the requirements for analyzing the set-up effect of LOTPs. It was also found that the LOTP capacities were overestimated when the EPWP was neglected. Beyond 28 days, the pile bearing capacity did not increase because the dissipation of the EPWP was almost fully developed. An equation for predicting the set-up effect of LOTPs installed using impact hammers is also presented.

Elucidating the role of soil hydraulic properties on aspect-dependent landslide initiation

Abstract. Aspect-dependent landslide initiation is an interesting finding, and previous studies have attributed this to the mechanical effects of plant roots. In the present study, an overwhelming landslide probability on a south-facing slope over a north-facing slope was found in a localized area with only granite underneath and high cover of Larix kaempferi. These observations cannot be attributed to plant roots but may result from factors related to hillslope hydrology. Differential weathering associated with hillslope hydrology behaviors such as rainfall water storage and leakage, pore water pressure, particle component, and hillslope stability fluctuation were used to examine these observations. Remote sensing interpretation using the high-resolution GeoEye-1 image, digitalized topography, and field investigations showed that landslides on south-facing slopes have a higher probability, larger basal area, and shallower depth than those on a north-facing slope. The lower limits of the upslope-contributing area and slope gradient condition for south-facing landslides were less than those for north-facing landslides. The higher basal areas of south-facing landslides than those of the north-facing landslides may be attributed to the high peak values and slow dissipation of pore water pressure. The absorbed and drained water flow in a given time interval, together with the calculated water storage and leakage measured during the rainy season, demonstrate that the soil mass above the failure zone for south-facing slope is more prone to pore water pressure, which results in slope failures. In comparison, the two stability fluctuation results from the finite and infinite models further verified that landslides on south-facing slopes may fail under conditions of prolonged antecedent precipitation and intensive rainfall. Meanwhile, those on north-facing slopes may fail only in response to intensive rainfall. The results of this study will deepen our knowledge of aspect-dependent landslide initiation from both classical mechanics and the state of stress.

Determination of hydraulic parameters of non-linear consolidation clay layers by type curve method

The consolidation of clay layers is of great significance for groundwater environmental protection, groundwater storage utilization, and land subsidence. In this study, the governing equation for the excess pore water pressure during the non-linear consolidation process of clay layers under load conditions is obtained based on the one-dimensional non-linear consolidation theory. Analytical solutions are then derived for clay layers with single or double drainage caused by the dissipation of the excess pore water pressure. With these analytical solutions, the groundwater dynamics and deformation of the clay layer are analyzed. Correspondingly, a type curve method is proposed to calculate the hydraulic parameters of the clay layer through laboratory experiments, which verifies the reliability of the analytical solutions. The study results show that the deformation of the clay layer predicted by the non-linear consolidation theory is smaller than that predicted by the linear consolidation theory. The deformation of the clay layer increases with the increase in the thickness of the clay layer, the compressive index, and the overburden load, while it decreases with the increase in the initial void ratio and the initial effective stress. The stable time, at which the consolidation of the clay layer is completed, increases with the increase in the compression index and the thickness of the clay layer, while it decreases with the increase in the initial void ratio, the initial effective stress, and the initial hydraulic conductivity. It does not vary with the load pressure. Conclusively, the deformation prediction based on the non-linear consolidation theory is more accurate and applicable to further load pressures.

A multi-field model for growth and dissipation of excess pore water pressure induced by slurry shield tunneling in semi-confined aquifer

This study focuses on the mechanism of slurry infiltration in front of the tunnel face during the construction of a slurry shield machine. A multi-field transient model is proposed to describe the growth and dissipation of the excess pore water pressure and the deposition of bentonite particles for slurry shield tunneling in the saturated semi-confined aquifer. Based on the conservation principle, the governing equations for the mass continuity of bentonite particles and volume continuity of slurry are derived with consideration of particle deposition and the elastic storage of the aquifer. The proposed model is validated by field measurements. The results indicate that the excess pore water pressure drops steeply close to the tunnel face and then gradually decreases to a stable value over several tunnel diameters due to the retardation of the infiltration zone. The retardation effect is positively correlated with the permeability coefficient of the soil and the filtration coefficient, while it is negatively correlated with the specific storage coefficient. The penetration distance of bentonite particles decreases with smaller soil pores and a higher slurry concentration. Besides, a quantitative equation is proposed to evaluate the influence of slurry concentration, filtration coefficient, and storability of the soil on slurry support efficiency.

Vacuum preloading combined with surcharge preloading method for consolidation of clay-slurry ground: A case study

A reclamation project was undertaken in Zhuhai, China, covering an area of 11.35 km2 with a clay-slurry thickness of 30 m. It is interesting to find a good reinforcement method, which is more suitable for strengthening such a large-scale dredged clay-slurry ground. Evidence from engineering practice shows that vacuum preloading or vacuum preloading combined with surcharge preloading method technology has certain advantages. However, further data is required to verify their performance in the field. This paper presents a case study using the conventional vacuum preloading and vacuum preloading combined with surcharge preloading method (vacuum pressure of 90 kPa, surcharge height of 3 m) to improve the thick clay-slurry ground for a subgrade engineering project in Zhuhai, China. A series of field monitoring, in-situ tests, and laboratory tests were performed to evaluate their treatment effect by analysis of vacuum degree, ground surface settlement, layered settlement, consolidation degree, lateral displacement, excess pore water pressure dissipation, and vane shear strength. The results showed that the ground treated via vacuum preloading combined with surcharge preloading method was more effective than conventional vacuum preloading. The vacuum degree of vacuum preloading combined with surcharge preloading method was slightly lower than that of conventional vacuum preloading, decreasing with depth. The settlement is increased by 55.56%, average consolidation degree is enlarged by 40.9%, lateral displacement can be augmented by 2.4 times, pore water pressure coefficient is less than 0.6, and undrained shear strength is amplified by 22.2%. These findings can be used to guide the design of the combined preloading method of the subgrade engineering project along the east coast of China.

Distribution and dissipation laws of excess pore water pressure based on pile-soil interface during pile-sinking in saturated clay

PHC pipe pile cooperated with jacked method is widely used in recent years. The excess pore water pressure of pile-soil interface caused during jacked PHC pipe driving would produce important effect on jacked pile construction and bearing characteristics. Two full scale jacked-in piles are penetrated into the clayey soil and studied by monitoring the law of generation and dissipation of excess pore water pressure. The law of excess pore water pressure with penetration depth and time is also analyzed. From this test results, excess pore water pressure of the pile-soil interface increases to the peak and then begins to decrease, but it remains large. The excess pore water pressure of S1 test pile pile-soil interface decreases from 201.4 kPa to 86.3 kPa, and decreases from 374.1 kPa to 114.3 kPa for S2 test pile. The excess pore water pressure of pile-soil interface rises first at the initial stage of consolidation, and it dissipates when the hydraulic gradient between pile-soil interface and soil around the pile disappears. The dissipation degree of excess pore water pressure reaches from 75% to 85%. The proposed solution provides certain engineering significance for jacked pile construction and bearing capacity design in the clayey foundation.

Shaking table tests on the liquefaction-induced uplift displacement of circular tunnel structure

Underground structures are susceptible to float and move upward during earthquakes when located in a liquefiable soil deposit. There are examples of this phenomenon in past major earthquake events. In this study, the uplift of circular tunnels in a liquefiable sand layer was investigated with a series of shaking table tests. The research has focused on the buried depth of the tunnel, tunnel diameter, tunnel weight, liquefaction extent, uplift mechanism, and factor of safety against liquefaction-induced uplift. According to the test results, the shallow buried depth, larger diameter, and lower weight can intensify the tunnel uplift, so the displacement in post-liquefaction time continues at the same rate as during the shaking time. Due to the shear-induced dilation, pore water pressure generation around the tunnel was reduced compared with that of the free field. The excess pore water pressure dissipation in the soil overlying the uplifted tunnel was significant, which leads to suction in the soil deposit. Furthermore, the acceleration response of overlying soil with the uplifted tunnel was similar to that of the free field. However, the soil acceleration response around the tunnel without uplift was similar to the base motion.

Rapid Treatment Using Vacuum-surcharge Preloading with Dynamic Consolidation Method: Laboratory Model Test

This study presents an experimental investigation of reinforcement effect of dredged fill obtained from the Oufei project of Wenzhou, China using improved method of vacuum-surcharge preloading with dynamic consolidation by five parallel laboratory model tests: four model tests with different tamping energy combinations and a control group of vacuum-surcharge preloading method. The water content after treatment of the vacuum-surcharge preloading method was close to the optimal water content obtained from standard compaction test. The treatment of improved method of vacuum-surcharge preloading with dynamic consolidation can improve reinforcement effect and shorten consolidation time. The tests with higher tamping energy have a higher range of improvement. Under the condition of the identical level of tamping energy, compared with the drop height, the weight of hammer plays a greater role in foundation reinforcement, embodying concretely in water discharge, crater depth, and dissipation of pore water pressure, water content, vane shear strength, and porosity. The findings from this study may benefit the engineering application and further research of the combined method.