Installation Of Columns Research Articles

Numerical Simulation of the Installation of Vibro Displacement Columns in Normally Consolidated Clay Using a Field Case Study

Numerical Simulation of the Installation of Vibro Displacement Columns in Normally Consolidated Clay Using a Field Case Study

Installation and construction technology of steel column under cup foundation of industrial plant

This article introduces the installation process of the steel structure column of a single-storey industrial factory building on a cup-shaped foundation, through the use of column bottom angle steel welding treatment, steel wedges, jacks, and the coordinated use of cable wind ropes, the steel column elevation adjustment measures are finally determined, which solves the elevation deviation caused by the cup-shaped steel column installation and the difficulty in the steel column hoisting process Controlled construction technology issues.

Case study: footing load test using stone columns in Port Fouad-Egypt

Installation of stone columns is an efficient technique to improve very soft to soft clay deposits that exist at shallow depths in many coastal areas in Egypt. The stone columns provide vertical stiff permeable members in the deposit to be improved. Upon loading, the presence of stiff columns reduces settlement, and increases the overall shear strength of the deposit, thus bearing capacity. Further, the high permeability of the columns provides drainage boundary that accelerates the dissipation of excess water pressure and thus increases the consolidation time rate of the soft soil. This paper presents analysis of a case history of footing load test founded on soft clay improved by stone columns for a project in Port Fouad, Egypt. The stone columns are of end-bearing type. The footing is analyzed using 3D finite element method. The analysis aims to; (1) show the importance of increased post-column installation coefficient of lateral earth pressure in light of the pre-shearing effect (Mesri and Hayat in Can Geotech J 30:647–666, 1993), (2) show the importance of considering the time-dependent settlement in evaluation either of the improvement technique and/or the design method, and (3) use the field measurements to evaluate and compare between the FEA method and the other published methods of estimating the settlement improvement ratio.

Quantification of arsine and phosphine in industrial atmospheric emissions in Spain and Colombia. Implementation of modified zeolites to reduce the environmental impact of emissions

Arsine (AsH3) and phosphine (PH3) in industrial emissions in the purification of liquefied petroleum gas (LPG) in two petrochemical plants, one in Colombia, the other in Spain—were the focus of this research. The study shows the challenges and contributions to environmental sciences in quantifying the magnitude of the environmental impact of these pollutants. AsH3 and PH3 were determined and quantified in industrial emissions, thereby demonstrating the source of their formation. Prior to this research, evaluations of these contaminants were not available either to the scientific community or to the public. The focus was on two stages of the LPG purification process: the deethanizer, where the most volatile compounds are separated from the LPG, and the splitter, where propylene is removed from propane. Monitoring was extremely complex because of strict safety requirements at each point. It was carried out over a period of one year, with 432 samples taken at different times to evaluate the stability and magnitude of possible environmental impacts. To overcome the analytical barrier of contaminating compounds at trace or ultra-trace levels, and their probable variability in pressure and temperature at the point of exit from each column, a new methodology was developed coupling a variable pressure sampler (VPS) to a gas chromatograph with a mass spectrometer. The analytical method employed a zeolite-packed prototype column which was validated and employed on an industrial scale, to mitigate the environmental impact of AsH3 and PH3 in the atmosphere. For the validation of each prototype, AsH3 and PH3 standards of 1.0, 0.1, 0.05, 0.01 and 0.005 ppm were used. The removal efficiencies varied between 97.97 and 99.91%. The RSD varied between 2.7 and 9.1% and the t-test of students of paired data showed P values greater than 0.05 at a significance level of 95%. In the affluents of the deethanizer, the highest levels of AsH3 and PH3 in the Colombian plant were 0.21 and 0.31 ppm respectively; in Spain they were 0.23 and 0.25 ppm. These values are higher than those established by OSHA, NIOSH and those quantified in the atmosphere by other studies. The concentration levels were identified at 40 TM h−1, which was the highest operating rate for the deethanizer and the splitter. For the splitter affluents, the highest values of AsH3 and PH3, both in Colombia and Spain, were 0.009 ppm. The installation of columns filled with zeolite at the exit points in these two plants, permitted obtaining effluents with a percentage removal greater than 99.95%, demonstrating the selectivity of the catalytic system as well as the effort to mitigate environmental impact.

Improving the Bearing Capacity of Marine Clay using Polyurethane Columns

Problematic soil such as marine clay causes structures or pavement to crack and collapse as marine clay possesses low bearing capacity. Therefore, ground improvement is usually conducted to improve the bearing capacity. Since the use of cement for strengthening weak soil is not environmental-friendly, the aim of this study is to improve the bearing capacity of marine clay using polyurethane (PU) columns. The properties of the marine clay collected from Batu Pahat determined were particle size distribution, Atterberg’s limits, specific gravity, and compressibility were determined. A series of small-scale physical modelling was conducted with a tank’s size of 500 mm x 500 mm x 200 mm. The 1:1 ratio of poly and isocyanate was injected into the cored hole for the column formation with the area improvement ratio was set as 12.6%. The loading process was conducted 1 day after column installation. Double tangent method from the stress-displacement curve was employed to determine the ultimate bearing capacity of the marine clay. The ultimate bearing capacity of the untreated marine clay was 50 kPa. In addition, the results showed that the ultimate bearing capacity of the marine clay increased with the length of the PU columns. A maximum improvement ratio of 220% was achieved for the end bearing PU columns. Comparing the improvement ratio with the published data showed that PU columns had a better performance than soil cement or deep mixing cement columns due to its lightweight and high strength. Therefore, the replacement of cement with PU is workable and sustainable in ground improvement method.

Geosynthetic-Encased Granular Columns Subjected to Vertical and Shear Loads

Granular columns are commonly used to support flexible structures over soft clay soils. The installation of such columns increases both the strength and stiffness of the ground. However, constructing these columns in clay soils having low cohesive strength of about 15 kPa is a challenge due to inadequate confinement. The columns may be encapsulated in geosynthetic tubes to enhance their constructability, strength and drainage properties. The geosynthetic encasement is also known to improve their performance under shear loading. This paper reviews the application of geosynthetic-encased granular columns for treatment of soft grounds. The design of these systems under vertical loads by two different methods is described in this paper. The performance of geosynthetic-encased granular columns under shear loads and the influence of geosynthetic encasement on the factor of safety of embankments supported on soft clay soils is discussed. The use of geosynthetic encasement of granular columns is seen to change the deep-seated foundation failure mechanism to toe failure mechanism.

Comparison of multiple monitoring techniques for the testing of a scale model timber Warren truss

This paper outlines the testing and monitoring procedure of a scale model Warren truss constructed of 2 inch × 4 inch (38 mm × 89 mm) members and bolted connections within a laboratory environment. Several forms of deflection monitoring and strain monitoring instrumentation were utilized throughout this laboratory testing phase of a longer-term research program. Instruments included: an automatic total station, linear variable differential transducers, light detection and ranging, electric strain gauges, and distributed optical fibre sensors. The distributed point load-testing regime included two configurations: ( i) the original truss configuration and ( ii) the installation of intermediate columns beneath the truss. Objectives of this phase included identifying instrument capabilities, limitations, and overall reliability/effectiveness with respect to representing the behaviour of the truss system. In addition, members of interest and critical monitoring locations along the Warren truss were determined. The purpose of this laboratory endeavour was to determine an optimized structural-health monitoring program prior to implementation in a heritage timber Warren truss structure within the infrastructure inventory of the Department of National Defence (DND). An options analysis of monitoring techniques was conducted whereby the effectiveness of each instrumentation type was evaluated according to relevant metrics/factors to determine an effective monitoring technique for this heritage building and other similar DND truss structures.

Experimental Study of the Effects of Installation of Sand Columns in Compressible Clay Using a Reduced Model

The present study focuses on the investigation of the behaviour of a reduced model of a reinforced soil massif by a sand column tested in the laboratory. These tests involved the installation of sand columns in clay specimens (kaolin) by different methods. The specimens thus obtained are subjected to the same oedometric loading program. The first part of this work aims to study the effect of the intensity of the compaction stress of the sand columns on the surrounding soil and the effect on the behaviour of the soil-column massif. The sand columns were installed with the soil replacement method and with compacting of the columns (WR_WC). Three different compaction stresses were used to install the columns. In the second part, a sand column 20 mm in diameter was installed by two methods: one with replacement of the soil (WR) and without compaction and the other with displacement of the soil (WD). A comparison between the two methods has been established. By determining the equivalent characteristics for the soil-column massif, this study made it possible to characterize the effect of the installation method of the columns on the settlements, the void ratioe of kaolin, the equivalent void ratio eeq of the massif soil-column and on the compressibility parameters of the massif (equivalent compression index Cceq and swelling index Cseq), by comparing the results obtained with those of the unreinforced soils that constitute the reference case. The results obtained showed that the techniques used for the installation of columns have significant effects on the behaviour of reinforced massifs.

Three Dimensional Numerical Study on Behavior of Geosynthetic Encased Stone Column Placed in Soft Soil

Ordinary stone column (OSC) reinforced soft soils undergo excessive settlements under vertical stresses due to the lack of adequate lateral support from the surrounding native soil. To overcome this issue, stone columns are suitably encased by a geosynthetic material having high axial stiffness, which provides the required additional confinement. A numerical analysis aimed at analyzing the effect of geosynthetic encasement on the load settlement behavior of geosynthetic encased stone columns (GESC) under vertical stresses is presented. Three dimensional (3D) models were developed in PLAXIS3D to simulate the behavior of stone column reinforced soft soils using the unit cell idealization concept. The numerical models were first validated with the help of experimental data of model tests on GESCs from literature. Various parameters were varied to quantify their impact on the load settlement behavior under column only loaded condition. The parameters varied include the diameter of GESCs, spacing to diameter (S/D) ratio, pattern of stone column installation, geosynthetic encasement stiffness, length of encasement, length of floating column, cohesion of soil and friction angle of stone column infill. Increase in the diameter of GESCs led to increased settlement for a particular vertical load intensity. The bearing capacity improved with increase in the geosynthetic stiffness, encasement length, length of floating GESCs, the cohesion of soil and the friction angle of the stone column infill. Increase in S/D ratio decreased the bearing capacity and triangular pattern of stone column installation was found to be more efficient. Moreover, the lateral bulging indicated a reducing trend upon increasing the axial stiffness of encasement.

Numerical Analyses of the Optimum Length for Stone Column Reinforced Foundation

The paper presents 3D numerical simulations that investigate the settlement performance for small groups of stone columns under a rigid circular footing. Particular consideration is given to the effects of stone column installation and load level on the optimum length of the stone columns. The results show that taking into account the installation effect by increasing the lateral earth pressure coefficient of the soil reduces the deformation of the columns and the surrounding soil. This leads not only to a reduction in the settlement of the footing but also to a reduction in the optimum length of the stone columns. This optimum length of columns is not constant, it increases with the increase in the load applied to the footing. However, overestimating the installation effect has a negligible consequence on the footing settlement and the optimum length of columns. In addition, the study shows that, for loads exceeding the working load levels of unreinforced soil, the optimum length of the columns is controlled by the extent of the total shear strains beneath the footing evolving with the applied load.

Numerical Investigation of Stone Column Improved Ground for Mitigation of Liquefaction

Installation of a stone column in loose soil is one of the robotics ground enhancement techniques that reduce the risk liquefaction and related ground deformation. However, the experimental investigation is costly and it is time-consuming to check the feasibility of this technique for the evaluation of ground subsidence and fluctuations in excess pore water pressure concerning different area ratios of a high modulus column. This paper presents a numerical investigation into shallow foundations underlain by a stone column as a liquefaction countermeasure. The Biot's consolidation equations are coupled with stress equilibrium equations in finite element modeling for cyclic loading conditions. The critical state model based on generalized plasticity theory was applied to model the nonlinear behavior of soil. The unknown displacement and pore pressure are evaluated using code written in FORTRAN 90. The granular column installation effect is also considered to predict displacements and excess pore pressure (EPP) at each time step. With the introduction of a granular column, considerable reductions were observed in displacements and EPP. The results underline the effectiveness of granular column installation as an effective measure in the mitigation of liquefaction.

Excess pore water pressure caused by the installation of jet grouting columns in clay

Abstract The injection of large volumes of pressurized water and grout into the subsoil during jet grouting generates a sudden increase in excess pore water pressure. This study proposes a theoretical approach to evaluate the variation in excess pore water pressure caused by the installation of a jet grouting column in clay, accounting for the chronological sequence of construction. The jet grouting column installation is simulated through the undrained expansion of a series of spherical cavities. Partial dissipation during the construction process is considered due to the gradual installation of the grouting columns. The relationship between the ultimate cavity radius (au) and the radius of the jet grouting column (rc) is established to represent the influences of both jetting parameters and soil properties on the generated excess pore water pressure. The proposed model is validated using two case studies, one conducted in Singapore marine clay and the other in Shanghai soft clay.

A laminar box apparatus for 1g testing of granular columns embedded in soft clay

Ordinary stone columns and geosynthetic-encased columns are widely used as a method of soil improvement for soft clay deposits. The behaviour of encased and unencased columns under the action of dynamic loads are not thoroughly understood. In order to shed light into the dynamic behaviour of granular columns and column-enhanced soft soil deposits, a novel large-scale laminar box assembly is designed together with provisions for instrumentation, consolidation of clay slurry and casing pipe pushing units for column installation. The laminar box is comprised of 16 individually supported laminates. The laminar box has inner areal footprint dimensions of 900 × 900 mm and a height of 1932 mm. The laminar box is utilised to study the behaviour of granular columns of varying reinforcement stiffnesses under dynamic loads. In order to make a thorough comparison of reinforcement stiffnesses on column behaviour, columns with different reinforcement arrangements are installed together in the same clay bed, and scaled earthquake accelerograms and sinusoidal base excitations are applied. Column response is studied through the reinforcement strains occurring on the encasement and the amount of vertical pressure sustained on the column during the dynamic load cases.

Sample preparation method for large scale shear testing of soft-clay and granular-column composites

This article is aimed at giving an overview of the testing equipment and sample preparation techniques for large scale shear testing of granular column enhanced soft clays. A novel testing device, designated Unit Cell Shear Device, is produced to enable clay bed consolidation and subsequent granular column installation within the clay bed. The device allows for studying the shear resistance of unit cells enhanced with slender vertical inclusions such as stone columns, geosynthetic encased stone columns, grouted piles, and conventional piles. The present study illustrates the novel clay slurry consolidation method, sample preparation sequence, testing device features, and the details of the actuators that shear the specimen. The strength parameters of the consolidated clay and the spatial distribution of engineering properties of clay are studied with different testing methods. The techniques prescribed herein present a viable method of clay bed preparation for laboratory testing purposes with the following advantages:• Homogeneous clay beds for testing• Reduced drainage path and accelerated consolidation time• Consolidation around a vertical inclusion to allow for column placement

Reduction of metro vibrations by honeycomb columns under the ballast: Field experiments

Environmental vibrations induced by subway operation are harmful to human health and structures when they exceed a certain value. Therefore, effective measures should be taken to reduce the noise and vibration generated by the metro. Therefore, a method to reduce the vibration by the installation of honeycomb Duxseal-cement columns under the ballast is presented in this paper. A honeycomb Duxseal-cement column was embedded in the subgrade of Qingdao Metro Line 13. A field test to measure the vibration of Qingdao Metro Line 13 was conducted. In addition, the time history curve of the vibration acceleration was obtained by processing the data and a Fourier transform was conducted for the test data to obtain a corresponding frequency spectrum curve. The spectrum curve was then converted into the one-third octave spectrum. Finally, the average value of the frequency vibration levels was determined. The comparison between the vibration generated by the metro filling and non-filling Duxseal-cement columns was investigated in detail. The test results show that the subgrade of metro in-filled by the Duxseal-cement columns obtains a better isolation effect than that of non-filling Duxseal-cement columns. The honeycomb Duxseal-cement columns present in the metros decrease their vibration accelerations in three directions, the X-, Y-, and Z-directions, by 33%, 28%, and 40%, respectively, compared with the original.

Field measured and simulated performance of a stone columns-strengthened soft clay deposit

ABSTRACTThis paper described field behaviour of a stone columns-reinforced soft foundation at a coal and ore stockyard followed by a comparison with numerical analysis. Performance of a 130-m-wide section with two ore stacks was recorded along a 500-operative day. An extensive instrumentation, comprising 14 sensors, was used to monitor the serviceability behaviour of the stabilized area. Complementary numerical analysis was performed using PLAXIS 2D finite element code, with which the increase in lateral earth pressure due to column installation was suitably modeled. The numerical analysis was carried out using plane strain approach, in which the stone columns were converted into the equivalent walls. Results showed that the adopted plane strain model could predict well measured total deformations of the reinforced foundation. Simulated curves of excess pore pressure also showed similar behaviour to the field data with a maximum value upon loading application followed by a gradual dissipation in consolidation stages.

Large-scale load capacity tests on a geosynthetic encased column

Stone columns have been used to minimize the settlement of embankments on soft soils but their use in very soft soils can become challenging, partly because of the low confinement provided by the surrounding soil. Geosynthetic encased columns (GECs) have been successfully used to enhance to reduce settlements of embankments on soft soils. This paper describes an investigation on the performance of encased columns constructed on a very soft soil using different types of encasement (three woven geotextiles with different values of tensile stiffness) and different column fill materials (sand, gravel and recycled construction and demolition waste, RCDW). The results of load capacity tests conducted on large-scale models constructed to simulate the different types of GECs indicate that the displacement method adopted during column installation can lead to an enhanced shear strength in the smear zone that develops within the very soft soil. In addition, breakage of the column fill material was found to affect the load-settlement response of gravel and RCDW columns. Furthermore, the excess pore water pressure generated in the surrounding soil during installation, was found to remain limited to radial distances smaller than three times the GEC diameter.

Enhancing discharge of spoil to mitigate disturbance induced by horizontal jet grouting in clayey soil: Theoretical model and application

The installation of jet grouting columns in fine-grained soils can cause significant disturbances to nearby structures, thereby undermining the reliability of this powerful technology. The high-pressure injection of large volumes of grouting materials coupled with the limited exhaust capacity of the boreholes often cause ground surface upheavals and lateral displacements. The problem appears particularly for horizontal columns injected at relatively shallow depths and in fine-grained soils. Systems employed to control the pressure in the injection cavity and fasten the spoil discharge represent an effective method to mitigate the ground disturbance. However, although the principle is well understood, there is no reliable analytical solution to predict ground movements caused by horizontal jet grouting and the resulting spoil discharge. This paper presents a simple calculation scheme to estimate ground movements induced by horizontal jet grouting. The method considers the jetting parameters, soil properties, and volume of discharged spoil. Further, a new equation is derived to calculate the radius of the plastic zone considering the discharged spoil. The proposed method is applied to interpret the observations obtained in two real case studies. The comparison of the calculation results and measured data confirms the effectiveness of the proposed method.

Variable-diameter deep mixing column for multi-layered soft ground improvement: Laboratory modeling and field application

Deep mixing columns are commonly employed for soft ground improvement. However, the diameter of a single conventional column is a constant and the area replacement ratio does not vary with depth. Hence, the conventional column is not the ideal solution for multi-layered soft grounds, where different layers have remarkably different soil properties. Accordingly, this study proposes a better solution, which is the variable-diameter deep mixing column with a large diameter in the soil layer having high compressibility and a small diameter in the soil layer having relatively low compressibility. In this study, small-scale laboratory model tests were firstly employed to compare the performance of two-layered soft grounds improved by a variable-diameter column and a conventional column. The additional vertical stress in the soil and the column, the excess pore water pressure, and the ground settlement were analyzed. Then, a field application of variable-diameter columns for multi-layered soft ground improvement was presented; the design considerations, column installation, and monitored settlement were introduced and analyzed. The results indicated that the additional stress in the soil and the column in the highly compressible soil layer were much lower in the variable-diameter column-improved ground than in the conventional column-improved ground. Consequently, the variable-diameter column-improved ground yielded less total settlement and less post-construction settlement compared to the conventional column-improved ground.

Pembuatan Rangka Atap dan Sarana Pendukungnya Bangunan Pengolah Sampah Desa Banjararum Kalibawang

Garbage in Banjararum is increasing due to the source of garbage that always increases. The source of garbage comes from stalls, schools, health centers, and agriculture. To handle the garbage needs a solution to reduce the negative impact on health society. Implementation is carried out with stages, measurements, installation of stakes, excavation of foundation, installation of roof, installation of columns, walls, roof truss, and roof cover. Followed by making a machine room, pools to collect the garbage. The results of this community service are that the garbage processing building consists in the engine room, Pools for garbage collection that will be processed.