Vibro Stone Columns Research Articles

Vibro stone as periodic wave barriers for train-induced vibration attenuation of Lamb and surface waves

The rising cost of traditional foundations (e.g., concrete piles) and their environmental limits have prompted using natural ways to strengthen poor soils. The Vibro stone column technique has grown in popularity in the building industry because it is a cost-effective and ecologically friendly way of strengthening the soil-bearing capacity of poor soil and avoiding the risk of soil liquefaction. The usage of stone columns in soft clay as periodic wave barriers to attenuate undesirable waves is numerically examined in this paper. The finite element method was used to investigate the band gap characteristics of Lamb and surface waves in the periodic structures of the stone column. In both wave analyses, eigenfrequency simulation, mode shapes simulation, frequency domain simulation, and time transient simulation are used to investigate the traditional vibroflot shape and proposed square and notch types vibroflot. It was established that the notch type vibroflot performed excellently in attenuating Lamb and surface waves compared to the traditional and square vibroflot types. The numerical outcomes in the frequency and time domains support the attenuation impact of finite Vibro stone in the band gap as well as the phenomena of attenuation broadening brought on by the dissipation of leak modes into the bulk. As a result, the proposed barriers can be used to shield the broadband incident waves generated by both Lamb and surface waves by trains in a tunnel.

Vibro stone column ground improvement practice in the United Kingdom

Vibro stone-column (VSC) techniques have been applied in the United Kingdom (UK) since the late 1950s–early 1960s, where they are one of the most commonly adopted ground improvement techniques. While there have been significant advances in VSC equipment development and also in the monitoring of the installation process for the VSC technique over the past 50 years, the design of VSC remains largely empirical and has changed very little since the 1970s. Publication of well-documented case histories and of instrumented field trials has also been limited over the past 25 years in the UK, in a VSC ground improvement market, which is predominantly commerce driven, based on the cheapest price. This has inherent implications for further advancement of design and innovation through funded full-scale field-based research. Current state-of-the-art of VSC in UK ground improvement is reviewed in the above context, together with comments on future challenges.

Bearing Capacity and Liquefaction Assessment of Shallow Foundations Resting on Vibro-Stone Column Densified Soil in Vallur Oil Terminal, India

Bearing Capacity and Liquefaction Assessment of Shallow Foundations Resting on Vibro-Stone Column Densified Soil in Vallur Oil Terminal, India

Embankment Supported by Low Area Replacement Ratio Stone Columns, Monitoring and Numerical Studies

The focus of this study was to evaluate the behaviour of a test embankment supported on vibro stone columns (VSCs) installed with a low area replacement ratio (7.56%) based on data obtained from field instrumentation complemented by analytical and numerical methods. The test embankment is 5.35 m high and was built on top of a soft soil treated with VSCs arranged in a 10-column × 10-column square grid. Analytical and two-dimensional finite element methods using the axisymmetric unit cell approach were also employed in the study to analyse the instrumentation data. The measured settlement-time curves, for the embankment axis, were compatible with finite element analysis in which the coefficient of permeability was continuously updated with the void ratio. Comparison was also favourable regarding measured and predicted values of settlements and improvement factors. All evidence indicates that VSCs installed with a low area replacement ratio (<10%) were quite effective in reducing the time for settlement stabilization and in providing adequate short-term stability against failure, but less effective in reducing the long-term settlement magnitude.

Experience in the design and operation of retaining walls of overpasses of the Central Ring Road on the base with soil improvement by vibro stone columns

Reinforced retaining walls were used on the overpasses of the Central Ring Road. To reduce the sedimentation of the base of these walls, to reduce the time of consolidation of the base, the transformation of soil properties by reinforcing vibro stone columns was used. In order to obtain an optimal result for the transformation of the properties of the base soils, increasing the reliability of the reinforced structures, comparative calculations were carried out with the variation of the parameters of the reinforcing elements. The method of quality control of the device vibro stone columns is improved.

Possible measures to reduce uneven deformation of floor structures of warehouse complexes

The article discusses measures to reduce uneven deformation of floor structures of warehouse complexes. The main goal was to identify ways to reduce the unevenness of sediment in the floors of the warehouse. To obtain optimal reinforcement of the floor structure of warehouses, to reduce unevenness of floor sediments, two methods are used: increasing the rigidity of floor structures and (or) increasing the rigidity of the base due to the use of piles or its reinforcement. This article presents the experience of applying the technology for converting the construction properties of soils using crushed stone reinforcing elements (vibro stone columns) when installing floors in warehouses. This technology allowed to reduce the deformation of the base of the floors, to reduce their reinforcement.

Опыт преобразования свойств грунтов основания подпорных стен путепроводов ЦКАД щебеночными армирующими элементами

Reinforced retaining walls were designed to minimize construction costs of Central Ring Road overpasses. To reduce settlement of the retaining walls, soil properties were improved by arranging vibro stone columns.

IN-SERVICE REMEDIATION OF A RAILWAY EMBANKMENT TO PREVENT SETTLEMENT

After optimization of the railway geometry for higher speed, a continuous settlement of the track occurred. Improvement of the embankment body was needed; however, a complete traffic interruption was not allowed. The reconstruction work has been done using the methods of special ground engineering such as vibro-stone columns and driven ductile piles.

Effect of Vibro Stone-Column Installation on the Performance of Reinforced Soil

AbstractEmpirical design methods for stone-column foundations are often on single stone columns or as a homogeneous medium of soil and column. These methods underestimate the capacity of the compos...

Briefing: The importance of field-based vibro stone column research

In seeking to increase the understanding of vibro stone column (VSC) behaviour and to improve current design methods, the importance of field-based VSC research, particularly in soft soils, cannot be underestimated. Some limitations of laboratory-based modelling research are highlighted here. Research should therefore ultimately include a field-based component if valid conclusions, applicable at the field scale, are to be drawn. Also highlighted is the need for greater consistency in the type and quality of data obtained and recorded at the field scale, in order to permit more effective comparisons of published field data, the need for better coordination within the research community and also the need for its engagement with industry to target the ‘unknowns’ while avoiding unnecessary repetition.

Non-plastic silty sand liquefaction, screening, and remediation

Assessing liquefaction potential, in situ screening using cone penetration resistance, and liquefaction-remediation of non-plastic silty soils are difficult problems. Presence of silt particles among the sand grains in silty soils alter the moduli, shear strength, and flow characteristics of silty soils compared to clean host sand at the same global void ratio. Cyclic resistance (CRR) and normalized cone penetration resistance (qc1N) are each affected by silt content in a different way. Therefore, a unique correlation between cyclic resistance and cone resistance is not possible for sands and silty sands. Likewise, the response of silty soils subjected to traditional deep dynamic compaction (DC) and vibro-stone column (SC) densification techniques is influenced by the presence of silt particles, compared to the response in sand. Silty soils require drainage-modifications to make them amenable for dynamic densification techniques. The first part of this paper addresses the effects of silt content on cyclic resistance CRR, hydraulic conductivity k, and coefficient of consolidation Cv of silty soils compared to clean sand. The second part of the paper assesses the effectiveness of equivalent intergranular void ratio (ec)eq concept to approximately account for the effects of silt content on CRR. The third part of the paper explores the combined effects of silt content (viz effects of (ec)eq, k, and Cv) on qc1N using laboratory model cone tests and preliminary numerical simulation experiments. A possible inter-relationship between qc1N, CRR, accommodating the different degrees of influence of (ec)eq, k, and Cv on qc1N and CRR, is discussed. The fourth part of the paper focuses on the detrimental effects of silt content on the effectiveness of DC and SC techniques to densify silty soils for liquefaction-mitigation. Finally, the effectiveness of supplemental wick drains to aid drainage and facilitate densification and liquefaction mitigation of silty sands using DC and SC techniques is discussed.

Stone column effectiveness in soils with creep: a numerical study

ABSTRACTWhile it is well established that vibro stone columns reduce primary settlement and improve bearing capacity, their effect on creep compression has largely been overlooked to date. However, with increasing pressure to develop marginal sites underlain by soft organic soils, the effect of ground treatment on creep is an important emerging issue in geotechnical engineering. In this paper, a series of axisymmetric unit cell analyses have been carried out using the PLAXIS 2D finite element program in conjunction with the Soft Soil Creep (SSC) model. Examination of the evolution of settlement improvement factor with time has indicated that the presence of creep leads to a lower ‘total’ improvement factor than would be obtained for primary consolidation settlement alone. Separate ‘primary’ and ‘creep’ improvement factors have also been derived; the latter are much lower than the former, but are nevertheless greater than unity. Creep results in a stress transfer process; as the soil creeps, vertical stress is transferred from the soil to the stone column. The additional load carried by the column induces additional yielding and shear-plane formation in closely-spaced columns. The additional increment of stress transferred to the already yielded column reduces its efficacy.

Briefing: Learning from vibro stone column failures

Much can be learnt about the behaviour of vibro stone column reinforced soils by undertaking a forensic examination of case histories of ‘unsatisfactory performance’, or what might be termed ‘failures’ in some applications and by identifying the main causes; it is not unusual for there to be more than one cause. Back analysis of such data provides an opportunity for greater insight into mechanisms that patently cannot be examined in successful case histories and also makes an important contribution to the advancement of both design and understanding, in addition to more effectively identifying and managing risk.

Briefing: Dry bottom-feed stone column construction in soft fine-grained soils

Increasing pressure to develop marginal soft clay sites, combined with increasing emphasis on environmentally sensitive and sustainable vibro ground improvement solutions, has seen significant advances in the use and application of the dry bottom-feed vibro stone column technique. It is clear, however, from the observations made during field trials of partial-depth vibro stone columns at the (former) Bothkennar soft clay research site in Scotland, that appropriate consideration needs to be given to stone column construction using the dry bottom-feed method in soft, sensitive, fine-grained soils, in order to minimise disturbance effects and optimise performance. Some of the more significant observations made, together with some suggested best practice guidance on stone column construction using the dry bottom-feed method, are outlined; some potential further research opportunities are also suggested.

The Role of Vibro-Stone Column for Enhancing the Soft Soil Properties

The Role of Vibro-Stone Column for Enhancing the Soft Soil Properties

Vibro-Stone Column Reinforcement Mechanism and Numerical Analysis

Numerical simulation of vibro-stone column is taken to simulate the installation of vibro-stone column. A relationship based on test is adopted to calculate the excess pore pressure induced by vibratory energy during the installation of vibro-stone column. A numerical procedure is developed based on the formula and Terzaghi-Renduric consolidation theory. Finally numerical results of composite stone column are compared single stone column.

Vibro-Stone Column Reinforcement Mechanism and Numerical Analysis

Numerical simulation of vibro-stone column is taken to simulate the installation of vibro-stone column. A relationship based on test is adopted to calculate the excess pore pressure induced by vibratory energy during the installation of vibro-stone column. A numerical procedure is developed based on the formula and Terzaghi-Renduric consolidation theory. Finally numerical results of composite stone column are compared single stone column.

Application of CFG Piles in Treatment of a Large Oil Tank Foundation

The original plan is to use vibro-stone column composite foundation to treat a large oil tank foundation. The result of strengthening is not satisfactory because of some factors, such as difficulty to control quality and long construction period etc. Treated ground can not meet the design requirements. The key in treatment design of tank foundation lies in bearing capacity and deformation of foundation, especially in non-uniform deformation. Through the analysis of site conditions, composite foundation of CFG piles is adopted. It is designed according to strength and deformation of dual control theory. Experimental results show that the compound used in foundation design is appropriate.

Ground improvement for infrastructure projects in Malaysia

Ground improvement techniques utilising vibro methods, deep soil mixing and grouting technologies are finding increasing application in Malaysia to solve a broad spectrum of geotechnical problems. Recent applications in Malaysia for four separate projects, namely jet grouting to form stable cutter-head interventions for a tunnel project, deep soil mixing to support deep vertical basement excavation with a limestone interface for a commercial complex, vibro concrete columns to found reinforced concrete tanks in a former domestic landfill for a sewage treatment plant, and vibro stone columns to support high reinforced soil walls for a highway, are described herein. The importance of quality control measures are emphasised and available proving methods are also discussed. The case histories presented demonstrate that the techniques can provide effective solutions to challenging engineering problems.

Emissions assessment related to vibro stone columns

This paper investigates a number of issues significant to the evaluation of the sustainability of vibro stone columns and, in so doing, discusses how a carbon dioxide emissions estimation tool could be developed for this area of ground improvement. It involves consideration of the use of recycled/secondary aggregates and how this choice affects the column design process, in terms of the durability of constructed works and the amounts of aggregates required. The paper concludes that assessing the sustainability of vibro stone column construction, in carbon dioxide emissions terms, is a complex process not based simply on whether recycled/secondary aggregates themselves are more ‘environmentally friendly' than primary aggregates. Instead, it requires care on the part of ground improvement engineers, who must balance geographical variation of aggregate sources against the amount of aggregate used in the vibro stone column construction. However, it is noted that the use of carbon dioxide provides a limited view of sustainable performance, and that the continued development of emerging assessment tools could help capture some of the true complexity of the decision-making process.