Compaction Pile Research Articles

Experimental and numerical evaluation of sustainable application of steel slag as an alternative to gravel in compaction piles

The study investigates the application of steel slag as an innovative material for compaction piles in the stabilization of soft soils, offering an eco-friendly alternative to conventional gravel compaction piles (GCPs). Through a comprehensive series of laboratory tests, field experiments, and numerical simulations, this study evaluated the performance, environmental impact, and long-term behavior of steel slag compaction piles (SSCPs). The key findings revealed that steel slag not only provides immediate soil improvement comparable to gravel but also exhibits significant time-dependent increases in strength and stiffness. Standard Penetration Test (SPT) N-ratios (N1/N0, where N1 = N value after improvement and N0 = N value before improvement) were similar for soils reinforced with SSCPs and GCPs after 0 months, but were about 30 % higher in SSCP-reinforced soils after 3 months. This increase was attributed to the cementation of steel slags, suggesting that the compaction pile with increased stiffness due to cementation acts as a compaction pile with an increased area replacement ratio (α). Environmental assessments confirmed that steel slag meets regulatory standards for soil contamination, positioning it as a sustainable option. Settlement analysis after embankment construction showed reduced and more uniform settlements with SSCPs, suggesting superior load distribution capabilities. Finite element analysis compared the behavior of SSCP-reinforced soils at varying α and stiffness of compaction piles, confirming that the cementation of steel slag produces an effect equivalent to increasing α in uncemented piles, thus enhancing the reinforcement effect.

Secondary consolidation simulation of peat with vertical drains under time-dependent loading

Preloading with vertical drains is an effective ground improvement technique used to accelerate the consolidation process. Generally, embankments are constructed over a period, by increasing the fill height with time. Hence, it is not always realistic to analyse embankments as a single ramp loading or an instantaneous loading. Although many studies have been conducted to calculate the settlement variation under time-dependent loading, those methods are complex in practical applications and do not consider the secondary consolidation settlement, which is important for very soft organic soils. In this study, the original Barron consolidation theory is applied to calculate the variation of settlement, pore water pressure and degree of consolidation due to incremental step loading of embankments, constructed on compressible soft organic soil, stabilised with vertical drains (gravel compaction piles, sand compaction piles and prefabricated vertical drains). The settlement predictions are compared with the actual settlement monitoring data obtained during the construction of road embankments, and pore pressure variation is compared with the results obtained from a case study reported in the literature. The comparisons show that the results obtained from the proposed method match very well with the actual field measurements.

A study on settlements of road embankments on soft ground using vertical drains

In civil engineering, the study of embankment settlement on soft ground is a vital geotechnical task in order to maintain serviceability of the road embankment, pavement, and facilities. This paper presents a study on settlements of road embankment on soft ground using vertical drains, including prefabricated-vertical drain (PVD), sand drain (SD), and sand compaction pile (SCP) on a number of packages of Hanoi – Haiphong Expressway Construction Project. The effectiveness of settlement prediction of vertical drain solutions is evaluated considering the ratios between the observed consolidation settlements and settlements predicted in the Detailed Design, in relation to the thickness of soft soil and the depth of treatment. Regression analysis is used to establish the correlation between the observed settlement and the height of embankment. The results show that (i) the design generally overestimated settlements; (ii) the ratios between observed and predicted settlements tend to positively correlate with the thickness of soft soil and the depth of treatment, and (iii) there are positive correlations between the height of embankment and the observed settlement. These correlations can be a valuable source of reference for anticipating settlements in basic design of highway projects with soft ground treated by vertical drains, in the regions that have geological stratum similar to Thabinh and Haihung formations of Bacbo Plain

Failure of Gravel Compaction Pile (GCP) Improved Embankment – Case Study

Due to the scarcity of suitable land, it becomes necessary to utilize marshy lands consisting of soft soil for infrastructure development. Soft soil has a problematic nature due to its high moisture content, high compressibility, high void ratio and very low shear strength. Hence, it is a responsibility of the geotechnical engineers to overcome these issues by adopting suitable ground improvement techniques. Gravel Compaction Pile (GCP) is one of the most popular soft ground improvement techniques used in the field. This technique has been successfully applied during the construction of the Colombo-Katunayake Expressway project and the Outer Circular Highway project. However, GCP technique has failed in the Southern Expressway Extension Project from Matara to Beliatta section. Therefore, in this study, the causes of the failure of the GCP improved embankment section were studied based on the field records. The slope stability of the embankment during construction was analysed using Matsuo and Kawamura's method. Back analysis revealed that once shear failure occurred in the subsurface, the shear strength of the soft soil reduces to its residual value and it takes longer time to regain its original strength. Further, it was noted that when the soft soil thickness is greater than 10 - 12 m, it becomes extremely challenging to improve the soft ground without any reinforcement. Therefore, it is strongly recommended to accurately interpret the subsurface characteristics in order to select the most suitable ground improvement technique.

Experimental Study on the Bearing Characteristics of Rigid-Flexible Long-Short Pile Composite Foundations in Thick Collapsible Loess Areas

The bearing and deformation characteristics of embankments with rigid-flexible long-short pile composite foundations (RLPCFs) in thick collapsible loess strata are not yet accurately understood. In this study, a large-scale field experiment was conducted, and screw (long) and compaction (short) piles were employed to reinforce a section of the foundation of the Lanzhou-Zhangye high-speed railway in thick collapsible loess. The pile load transfer, foundation settlement, pile-soil stress distribution, and load sharing characteristics were analyzed to reveal the bearing properties of the composite foundation. The results show that negative friction arises along the upper part of the pile, and the neutral points of the short pile and long pile are located at 2/5 and 1/3 down the pile lengths, respectively. The short pile eliminates the collapsibility of the shallow loess and enhances the foundation's bearing capacity. The long pile transfers the load of the shallow foundation and pile top to the deep foundation through lateral friction, which reduces the settlement of the shallow foundation. When the soil arch in the embankment is fully formed, the short pile bears approximately 20% of the load, while the long pile and the soil between piles bear 80%. With the increase in embankment filling height, the load borne by the long pile rises, and the load borne by the soil between piles decreases gradually. The top settlement of the cross-section of the composite foundation is distributed in a concave basin shape, and the maximum settlement occurs in the center of the embankment. The parameters of the short pile can be obtained on the basis of the collapsibility grade and bearing capacity of the loess foundation, the length and area replacement rate of the long pile can be obtained based on the settlement control requirements of the superstructure of the composite foundation, and the lateral friction of the long pile can be increased by increasing the roughness of the pile and setting the screw.

Shaking Table Tests on Model Ground Simulating Constructions of Sand Compaction Piles －Difference of Behavior between Improved and Unimproved Ground－

Shaking Table Tests on Model Ground Simulating Constructions of Sand Compaction Piles －Difference of Behavior between Improved and Unimproved Ground－

Analyses of the improvement effectiveness of Sand Compaction Pile method in past earthquakes and recent findings

Analyses of the improvement effectiveness of Sand Compaction Pile method in past earthquakes and recent findings

Hollow cylindrical torsional shear test simulating subsoil stress history during construction of Sand Compaction Pile

Hollow cylindrical torsional shear test simulating subsoil stress history during construction of Sand Compaction Pile

Geotechnical properties of natural sand-mixed granulated blast furnace slag applied to the sand compaction pile method

Granulated blast furnace slag (GBFS) has more advantageous properties over natural sand, such as lightweight, higher shear strength, and higher permeability. Therefore, it is regarded as a potentially promising substitute for natural sand in the ground improvement using the sand compaction pile (SCP) method. Due to the relatively rapid solidification, however, which is induced by the latent hydraulic property of GBFS, the permeability of the installed GBFS compaction pile (GBFSCP) decreases quickly, and such an application becomes difficult for the case of SCP with low sand replacement area ratio (LSRAR). So, to decelerate the permeability reduction of GBFSCP, different GBFSs, and natural sands were collected in Japan and Vietnam, and the specimens were prepared by changing the mixing ratio of sand to GBFS from 20% to 80%. Then, firstly, fundamental geotechnical properties of sand-mixed GBFS without hydration were observed. Secondly, the specimens of sand-GBFS mixture were cured in seawater at the temperature of 80°C for 3 days to 380 days. The unconfined compressive strength, permeability, and hydration reaction rate of the hydrated sand-mixed GBFS specimen were measured.
 In conclusion, the geotechnical properties of the unhydrated sand-mixed GBFS become more advantageous than those of natural sand. In addition, by mixing with natural sand, the hydration reaction rate and the solidification of GBFS are controlled. This means that it is possible to keep the compressive strength and the permeability at the predetermined conditions and, in turn, to satisfy requirements for the SCP method with LSRAR. In addition, a simple estimation method of the unconfined compressive strength was proposed for the hydrated sand-mixed GBFS specimen.

Utilizing a new columnar inclusion approach to treat loose and granular soils

This study introduces an innovative method to improve the load-bearing properties of loose fine-grained soils, mitigate geodynamic stress-related risks to supported structures, and address the issue of end-of-life tire waste. This technique involves blending shredded end-of-life tires with sandy soil and compacting the mixture into sand-rubber compacted piles (SRCP), thereby enhancing both the soil's load-bearing capacity and its ability to absorb energy. As per the ASTM classification system, the sand used in this study falls into the category of fine to medium poorly graded sand, with particle sizes ranging from 4.75 mm and an average particle size (D50) of 0.2 mm. An experimental program was devised to investigate the physical and mechanical properties of this composite material. Field plate load tests (FPLT) were conducted to assess the effectiveness of the proposed technique, taking into account factors such as the initial relative density of the soil, the ratio of rubber to sand (R/S) in the mixture, and the distribution of piles in the surrounding environment. The results from the plate load tests revealed that when SRCP was applied to soil with a relative density of 40 %, the ultimate load-bearing capacity increased by 100 %.

Comprehensive Experimental Investigation of Improved Clay Ground by Sand Compaction Pile Varying from Low to High Area Replacement Ratios

Comprehensive Experimental Investigation of Improved Clay Ground by Sand Compaction Pile Varying from Low to High Area Replacement Ratios

Features of the combined impact of driven compaction piles and the associated subsoils

Features of the combined impact of driven compaction piles and the associated subsoils

A novel numerical strategy to analyse the installation and set-up effects of sand compaction piling

Sand compaction piling has been long recognized to exert considerable influence on the treated soils in various aspects. One noteworthy regard is the strength set-up or the set-up effect in soil due to the sand compaction pile installation. However, due to its complex nature, it is extremely difficult to numerically model the actual piling process, which is characterised mainly by the repeated withdrawal and re-driving of the casing tube and by the gradual expansion of the sand column. Crude simplifications of various forms had thus to be adopted in the past. This paper reports the development of an innovative approach that can replicate not only the actual sand compaction pile installation process but also the post-installation soil consolidation phenomenon. With that, the set-up effect can be realistically reflected by numerical means.

Bearing capacity, elastic modulus, and modulus of subgrade reaction of soft soil improved by floating stone compaction pile group

ABSTRACT Observations of Plate Load Tests conducted on 12 locations in the coastal belt of central Kerala, India, to investigate the performance of soft soil improved by Floating Stone Compaction Pile (FSCP) groups are presented in this paper. The soil in the sites chosen was predominantly cohesive with low shear strength. FSCPs 100mm in diameter spaced at 300mm center-to-center, and constructed using 6 mm broken stones were installed to a depth of 5.0 m. The improvement in bearing capacity, Elastic Modulus, and Modulus of Subgrade reaction of the soil were evaluated after 6 months. From the results, it was seen that an average increase of 85% in modulus of subgrade reaction, 52% for bearing capacity, and 90% for elastic modulus was gained due to the installation of FSCPs. The additional cost involved for the installation of FSCPs is only around 2% of the total cost for the construction of the structure, proving the method to be a cost-effective option.

Investigating the advantage of copper and steel slags as partial replacement material in a sand compaction column in stabilizing the soft clay

ABSTRACT The current study aims in finding the utilization of Industrial waste such as copper and steel slags as a partial replacement material for sand in Sand Compaction Pile (SCP) in proportions of 5%, 10%, 15%, 20%, 30%, and 40% by weight. From the direct shear tests, it is observed that the angle of internal friction increases from 27.59° to 40.1° and 34.82° for copper and steel slags, respectively. The tests are done by installing the SCP in a soft clay in California Bearing Ratio mould and it is tested under soaked and unsoaked conditions. The optimum percentage found from the study for both the slag material is 30%. Tests were also done by air-curing the composite soil within the mould for 7 days and water-curing the sample under soaked conditions for 4 days for the optimum replacement percentage.

Application of CPT test in the evaluation of the test effect of lime soil compacting pile

In the course of highway construction and use in loess area, subgrade settlement disease is common and has great destructiveness. The cone penetration test (CPT), especially the pore pressure cone penetration test, can provide three continuous readings along the exploration depth cone tip resistance, lateral friction resistance and excess pore water pressure. In this paper, CPT tests are carried out in the losses areas in Shanxi, China. Some data and curves are obtained by using CPT, which are quite different from those obtained by conventional drilling, reflecting the soil layer characteristics of the subgrade section, in order to provide a reference for similar projects. The results showed that CPT has a strong advantage in the analysis of the effect of compacted pile in the treatment of pile length and the improvement and reduction of indicators of different layers along the depth direction. However, the correlation between the static penetration and the compaction coefficient commonly used in the current norms still needs to be further studied to enhance the correlation analysis with detection parameters.

Effects of the Ground Reinforcement on the Dynamic Behaviors of Compacted Loess Embankment with Ballasted Track

An embankment is needed to satisfy the requirements for the longitudinal slope of railway lines, and ground reinforcement is also generally required in loess regions. The present study attempted to understand the effects of different ground reinforcement measures on the dynamic characteristics of a track–embankment–ground system. To this end, the critical speeds and the distributions of dynamic stress and environmental vibration were analyzed using a 2.5D finite element method. Three typical ground reinforcements, including dynamic compaction ground (DCG), soil–cement compacted pile composite ground (SCG) and CFG pile composite ground (CFGG), were used. The results indicate that the train speed (critical speed I) at which the maximum vertical displacement of the track occurs is universally higher than that (critical speed II) at which the wave propagation phenomenon occurs. The lower boundary limit of the peak region in the dispersion relationship can be selected as the reference value of critical speed II. Moreover, the values of critical speed I obtained using the DCG, SCG and CFGG models were around 92, 105 and 127 m/s, respectively. For critical speed II, the values were 75, 80 and 115 m/s. Once the train speed exceeded critical speed II, the vibration was confined to the embankment in the CFGG model, as evidenced by the isolation of the wave propagation from the embankment to the ground as well as the increasing dynamic stress in the embankment. After reinforcement, the dynamic stress, dynamic influence depth (DID), critical speed and resonant frequency increased. Additionally, the DID stayed around the 3–6 m range at all speeds.

Calculation Model of Compaction Coefficient of Soil among SP−PSC Pile Group on Collapsible Loess Foundation

Collapsible loess is a kind of soil with special properties, and is widely distributed in China. When it is not wetted by water, its strength is generally high and its compressibility is low. However, when collapsible loess is wetted by water under a certain pressure, the soil structure will be rapidly destroyed, resulting in large additional subsidence. Therefore, when engineering constructions on collapsible loess sites are carried out, appropriate foundation treatment measures must be taken to eliminate foundation collapsibility. Because of their advantages, static pressure plain soil compaction (SP−PSC) piles are widely used for collapsible loess foundation treatments in China. However, at present, there is still a lack of accurate understanding of the distribution of compaction coefficient of soil among SP−PSC pile groups on collapsible loess foundations. The present study systematically investigated the distribution of the soil compaction coefficient among SP−PSC pile groups based on SP−PSC pile group tests and finite element analyses. The effect of different factors on soil compaction coefficient was analyzed and explored, including the pile diameter and length of SP−PSC piles, the soil moisture content, the pile spacing within the SP−PSC pile group, and the depth to ground. Finally, the simplified calculation models of the compaction coefficient of the soil at the center of pile group and at the midpoints of adjacent piles were analytically formulated. These models established a theoretical basis for the design and construction of SP−PSC pile groups on collapsible loess foundations.

Experimental Study on the Dynamic Characteristics of a New Long-Short Pile Composite Foundation under Long-Term Train Load

Long-short pile composite foundation (PC-LSPCF) composed of part-screw pile and cement-soil compaction pile is a new railway foundation treatment method, which has been widely used in high-speed railway construction projects in China. To explore the dynamic characteristics and deformation characteristics of railway PC-LSPCF under long-term train loads, the dynamic characteristics of long piles, short piles, and soil between piles under long-term train loads are tested by an indoor dynamic model test. The dynamic amplification of pile and soil under dynamic load and the temporal and spatial distribution of peak response are analyzed, and the stress and deformation development mechanism of PC-LSPCF under cyclic loading of large-cycle trains is revealed. The results show that the neutral point of the long pile is at 1/2 of the pile length and that of the short pile is at 3/8 of the pile length. The part-screw pile has a certain absorption effect on vibration energy. The deformation of a long-short pile composite foundation under long-term train loads can be divided into three stages: extreme growth, transition, and stability. The train speed is negatively correlated with the cumulative settlement of the long-short pile composite foundation. The higher the train speed, the smaller the cumulative settlement, and the smaller the number of cycles of the N-S curve entering the gentle period. As the number of train cyclic loads increases, the load-sharing relationship of the long pile-short pile-soil system will be redistributed. The research results have important reference significance for the optimization design of high-speed railway foundation treatment.

Application of BIM in Tunnel Design with Compaction Pile Reinforced Foundation Carrying Carbon Assessment Based on Advanced Dynamo Visual Programming: A Case Study in China

Carbon emission assessment in civil engineering has gained worldwide attention due to the negative effects of greenhouse gases on the environment. Significant amounts of building materials and electric power are consumed during the construction of tunnels, causing the release of greenhouse gases into the atmosphere. In addition, building information modeling (BIM) can be utilized to realize the computerized design of tunnels, and improve construction efficiency. However, the traditional BIM software (Autodesk Revit) lacks tunnel components and is unable to directly create a three-dimensional tunnel axis. This paper adopted BIM to build a three-dimensional model of the tunnel components for tunnel and carried out batch parameterization and component lofting based on Dynamo visual programming. The BIM of the tunnel guided the construction procedures and improved the construction efficiency. Based on the emission coefficient method, we calculated the carbon emissions from each component and loaded them into the BIM during the parameterization process. After the tunnel modeling design was completed, a bill of quantities was obtained. Then, the carbon emissions from the whole tunnel construction were calculated according to the bill. Thus, the combination of BIM technology and tunnel engineering was realized; this has practical significance for reductions in emissions, and cleaner construction in relation to tunnel engineering.