Settlement Influence Factors Research Articles

Approximate settlement influence factors for bucket foundations

ABSTRACT The response of bucket foundations for offshore structures has received significant attention from researchers but most of the reported studies focused on ultimate capacity. In this study, a comprehensive series of finite element analyses have been performed to investigate directly how the skirt geometry affects the elastic settlement of bucket foundations of arbitrary rigidity embedded in either a homogeneous or heterogeneous soil medium with finite layer thickness. The effect of soil drainage conditions is also explored. The results are graphically presented in the familiar form of settlement influence factors which can be used in hand calculations to predict the settlement of bucket foundations for a wide range of practical cases. Approximating expressions that capture the settlement influence factors well are developed. A worked example is given to illustrate the use of the graphical and approximating solutions.

An Analytical Study of Annular Raft on Granular Piles

Abstract Rafts are frequently used to design foundations on soft soils to minimize the overall and differential settlements of structures built on them. In many cases, the raft alone can offer sufficient bearing capacity and all that is needed to restrict foundation settlements to a predetermined level with a few widely spaced piles. Granular piles (GPs) can be used due to their several advantages over steel or concrete piles. An annular raft foundation is generally provided for overhead water tanks, chimneys, etc. The provision of granular piles underneath the annular raft foundation not only increases the capacity of the foundation but also minimizes the settlement to an acceptable level. The present study deals with a rigorous analysis of annular raft foundation supported by GPs based on the continuum approach. A new numerical method is developed with geometric considerations for excluding the loaded pile portion from the region of the raft area by considering two distinct zones. This article introduces a novel approach, the annular raft over granular piles, which represents an innovative solution in geotechnical engineering. This innovation has the potential to improve the efficiency and effectiveness of foundation design in various construction projects. The response of annular raft foundation with GPs is evaluated in terms of settlement influence factor (SIF), load shared by granular piles (in %), and normalized shear stress variation along the GP–soil interface. The present study reveals that the presence of the pile influences the stress distribution locally. The stiffness of GP, relative length of GP, relative size of the raft influence the settlement and load sharing of annular raft with GPs.

Analytical evaluation of partially stiffened granular piled raft with the effect of rigidity of bearing stratum

ABSTRACT Present study aims to improve the utilisation of granular piles (GP) for ground improvement by analysing the partially stiffened end-bearing granular piled raft (EBGPR) resting on the bearing stratum (BS). The study incorporates the use of the mirror image method and an elastic continuum approach to estimate the vertical settlement of the soil at the interface of the EBGPR. The study focuses on finding normalised variables such as settlement ratio, settlement reduction factor, settlement reduction factor for the BS, settlement influence factor (SIF), SIF for any depth, percentage load on the GP and on the base and normalised shear stress along the length of the GP with the effect of relative size of the raft. Based on the study, it was concluded that the SIF tends to decrease with an increase in the stiffening factor for the top portion of the GP. This finding suggests that the stiffening of the upper part of the GP can improve its strength and stiffness, and can potentially enhance the performance of the EBGPR foundation. Overall, the study is a comprehensive analysis of the partially stiffened EBGPR foundation, and provides useful insights into the behaviour and performance of such foundations.

Interaction analysis of two floating granular piled raft units

ABSTRACT The pile–soil–raft interactions remain a daunting problem in the study of piled-raft foundations. A simple analytical continuum approach is implemented in the present research to analyse the interaction between two granular floating piled-rafts. The formulation uses the equations of Mindlin and Boussinesq for the estimation of the displacements for forces in the interior and on the surface of the continuum. Settlement influence factor, interaction factor, the normalised shear stresses along the granular pile (GP)-soil interface, the percentage load shared by GP, the percentage load transferred to the GP base, and the normalised contact pressure distribution underneath the raft are evaluated and presented for design.

Analytical and numerical evaluation of the effect of stiffening with the rigidity of bearing stratum on the reduction of settlement for a partially stiffened granular pile

ABSTRACT A traditional approach of using granular pile (GP) is an economical and effective technique to achieve the objectives of ground improvement. If GP is partially stiffened from the top of GP, their overall performance gets improved. Stiffening of GP can be achieved by replacing partially the upper portion of GP with a material having superior mechanical properties, e.g. by geosynthetic encased columns, SDCM (stiffened deep cement mixing), etc. Analyses of a single partially stiffened (SPS) floating and end-bearing GP is presented in this paper in terms of settlement influence factor (SIF) for the top of GP, settlement reduction factor (SRF), percentage load shared by the base (PLSB) of GP. Analytically the variation of normalised shear stress (NSS) distribution along the length of the partially stiffened GP is presented in this paper. SIF for the top of GP was found to decrease, while the PLSB of GP was found to increase, with an increase in the stiffening parameters viz. stiffening factor (SF) and the percentage length of stiffening (PLS) from top of GP for a partially stiffened GP.

Prediction of settlement influence factors for laterally loaded short piles by using a continuum-based soil model

An existing continuum-based model for a laterally loaded pile embedded in layered soil is developed for long piles in which the vertical deformation of soil is neglected. However, the model is unsuitable for short piles, such as large-diameter caissons and suction buckets, because the soil will have considerable vertical deflections. Thus, this study attempts to modify the existing continuum-based model for laterally loaded long piles, and the aim is to render the model applicable for short piles with large diameters. Two resisting moments are added to the model: A moment on the base of the pile and a moment due to the vertical shear stress of the soil surrounding the pile. The modified continuum-based model is examined in terms of settlement influence factors and validated with the model with finite element (FE) analysis. Our linear static analysis found that the proposed modified continuum-based model is in good agreement with the FE method for short and long piles.

Analyses and settlement study of a group of two, three and four partially stiffened floating granular piles

ABSTRACT Use of granular pile as a ground improvement technique in case of soft soils is one of the reliable and economic options. Analysis of a partially stiffened group of granular floating piles has been numerically assessed and presented here. Partial stiffening simply means that instead of using conventional material for making the granular pile (GP) in its full length, top region is replaced partially by some suitable material, having better mechanical properties, i.e. higher deformation modulus. Various normalised parameters like settlement influence factor for top of GP, settlement interaction factor, settlement reduction factor, percentage load shared by the base and shear stress distribution along the length of the granular pile are evaluated. The settlement influence factor for top of GP is found to decrease with the increase in the values of the stiffening parameters. The interfacial shear stresses get redistributed along the length of the granular pile.

Effect of Nonlinear Non-homogeneity of Floating Granular Pile and Soil on Settlement

Ground improvement using granular piles (GPs) is a good alternative to a concrete pile because it increases the load carrying capacity and minimises the settlement of foundations. The present study incorporates the true field conditions with consideration of the nonlinear variation of deformation modulus for GP and soil both. An analytical methodology developed to incorporate nonlinear deformation modulus in pile and soil matrix. Thus, the response of non-homogeneous floating granular pile in non-homogeneous soil is evaluated with respect to settlement influence factor, normalised shear stresses, axial load distribution along granular pile–soil interface and percentage of load transferred to the base to study its true behaviour. An analytical approach based on the continuum is presented in terms of nonlinear variation of deformation modulus of the granular pile and surrounding soil. Formulations for pile elemental displacement equations incorporating linear to nonlinear non-homogeneity parameters, α and δ, for floating granular pile and β and ϒ for non-homogeneous soil are presented. With the increment in relative length of the pile (L/d), the reduction in the magnitude of settlement influence factor further increases. The increase in linear and nonlinear non-homogeneity parameters of soil, β and ϒ, reduces the shear stresses in the upper region of soft soil along with granular pile–soil interface and transfers them to the lower stiffer region of soil.

Analysis and settlement evaluation of an end-bearing granular pile with non-linear deformation modulus

Abstract Ground improvement with granular piles increases the load-carrying capacity, reduces the settlement of foundations built on the reinforced ground and is also a good alternative to concrete pile. Granular piles or stone columns are composed of granular material, such as crushed stone or coarse dense sand. An analytical approach based on the continuum approach is presented for the non-linear behaviour of the granular pile. The formulation for pile element displacement is done considering the non-homogeneity of the granular pile as it reflects the true behaviour and also accounts for the changes in the state of the granular pile due to installation, stiffening and improvement effects. The present study shows that the settlement influence factor for an end-bearing granular pile decreases with increase in the relative stiffness of the bearing stratum. The settlement influence factor decreases with increase in linear and non-linear non-homogeneity parameters for all values of relative length. For a shorter pile, the rate of decrease of the settlement influence factor is greater in comparison to that for a longer pile. Shear stress at the soil–granular pile interface reduces in the upper compressible portion of the granular pile and increases in the lower stiffer portion of the granular pile due to the non-homogeneity of an end-bearing granular pile.

Analysis and Settlement of Partially Stiffened Single and Group of Two Floating Granular Piles

Ground improvement is a technique which a geotechnical engineer normally faces whenever soft soil is encountered. There is a need to look for some economic and feasible option for the provision of foundation in such cases, and one of the option available, is to use the granular pile (GP). The present paper analyzes a single partially stiffened floating and group of two partially stiffened floating GPs. Partial stiffening simply means that the material of the GP is replaced partially in the top region of granular pile by some material, having good mechanical properties i.e. higher deformation modulus e.g. geo-grids, stiffened deep cement mixing, etc. Mathematical formulation and its numerical solution is developed to incorporate the stiffening of granular pile at top portion in the analysis to study its behavior. The effect of stiffening factor i.e. ratio of modulus of deformation of stiffened to un-stiffened portion of GP and percentage length of stiffening i.e. ratio of length of stiffened portion to the total length of the pile are studied on various parameters such as settlement influence factor at top, settlement interaction factor, settlement reduction factor, normalized shear stress distribution along the length of the pile and percentage load transferred to base. As obvious, the settlement influence factor at top decreases with the increase in the stiffening parameters viz. stiffening factor and percentage length of stiffening.

Immediate Settlement of Ring Footings Resting on Inhomogeneous Finite Stratum

This paper describes the immediate settlement of uniformly loaded rough ring footings with any stiffness on an inhomogeneous finite layer overlying a rough rigid base, which is not yet covered in the literature. Numerical solutions for a wide range of geometric and material combinations are obtained by finite element method. The effects of dimensionless parameters related to footing internal opening, compressibility, footing stiffness, finite layer thickness and soil inhomogeneity are examined. Based on the results, design charts are presented in the form of settlement influence factors that can be used to calculate the immediate settlements at the inner and outer points of ring footings.

Settlement Analysis of Non-homogeneous Single Granular Pile

Stone columns or granular piles are frequently used for the stabilization of soft clays and silts and loose silty sands with large amount of fines. Granular piles/stone columns improve the performance of foundations on soft ground by reducing the settlement to an acceptable level and also by increasing the load carrying capacity. The columns of granular material also help to speed up consolidation effects in the soft ground. Consideration of granular piles often to be homogeneous may not be true always and may lead to errors in the predictions of response of granular pile reinforced ground. The consideration of non-homogeneity of granular pile in terms of its non-linear behaviour of deformation modulus for settlement analysis could represent its in situ behaviour closer and more realistic. Present analysis carried out study of non-homogeneous granular pile in homogeneous soil based on the continuum approach in terms of settlement influence factor, normalized axial load and mobilized stress distributions with depth and the percentage of applied load transferred to the base. This analysis is applicable for a range of linear to non-linear analysis of deformation modulus of granular pile from top to tip.

PENGARUH FAKTOR BERMUKIM MASYARAKAT TERHADAP POLA PERSEBARAN PERMUKIMAN DI KAWASAN RAWAN BENCANA LONGSOR KABUPATEN MAGETAN

<em>Housing and settlements is fundamental human need to do daily activities for the survival of mankind. The community in determining the location of settlements have basic considerations that affect them in choosing a location for a settlement. The basic consideration is composed of several factors, including accessibility, environment, job opportunities, level of service, in addition to psychological factors, socioeconomic factors and historical cultural factors. Basically the location of settlements or housing are not allowed on the mountain slopes are potentially landslide disaster. Landslide that is threatening the survival of human beings who lived in the area. The danger of a disaster is a natural or artificial phenomena which have the potential to threaten human life, loss of property and damage to the environment. The area of the slopes of Mount Lawu which has a dense contour and topography make settlement patterns that are located in the area most are clumped as well as the distance between one another with their distance. There are several factors that affect the formation of settlement patterns, namely economic, cultural, institutional and customs. The issue of this study is to examine how the influence factors of settlement in the area of landslide-prone Magetan against pattern of settlement that is formed in the area. This study discusses the characteristics of the factor pattern of distribution in the community, the establishment of settlements and the influence factors of settlement against the spread pattern of settlement in the area of the landslide-prone Magetan by using multiple linear regression analysis. The community has its own considerations against the selection of the location of the settlement which made slopes be settled and be against the formation of settlement patterns in the Poncol Districts and Plaosan Districts which located on the slopes of Mount Lawu. Of research results obtained in the area of community based factors prone to landslide has no influence on the pattern of the spread of settlements that was formed in the area.</em>

Settlement analysis of rectangular piles in nonhomogeneous soil using a Winkler model approach

SUMMARYAn analytical approach using a Winkler model is investigated to provide analytical solutions of settlement of a rectangular pile subjected to vertical loads in nonhomogeneous soils. For a vertically loaded pile with a rectangular cross section, the settlement influence factor of a normal pile in nonhomogeneous soils is derived from Mindlin's solution for elastic continuum analysis. For short piles with rectangular and circular cross sections, the modified forms of settlement influence factors of normal piles are produced taking into account the load transfer parameter proposed by Randolph for short circular piles. The modulus of subgrade reaction along a rectangular pile in nonhomogeneous soils is expressed by using the settlement influence factor related to Mindlin's solution to combine the elastic continuum approach with the subgrade‐reaction approach. The relationship between settlement and vertical load for a rectangular pile in nonhomogeneous soils is available in the form of the recurrence equation. The formulation of settlement of soils surrounding a rectangular pile subjected to vertical loads in nonhomogeneous soils is proposed by taking into account Mindlin's solution and both the equivalent thickness and the equivalent elastic modulus for layers in the equivalent elastic method. The difference of settlement between square and circular piles is insignificant, and the settlement of a rectangular pile decreases as the aspect ratio of the rectangular pile cross section increases. The comparison of results calculated by the present method for a rectangular pile in nonhomogeneous soils has shown good agreement with those obtained from the analytical methods and the finite element method. Copyright © 2014 John Wiley & Sons, Ltd.

Research on deposition and consolidation behaviour of cohesive sediment with settlement column experiment

The deposition and consolidation behaviour of cohesive sediment is studied with a newly developed integrated settlement column system. This system, which includes graduate (glass) and settlement column (PMMA), has been proved an effective way to study the settlement of sediment suspension with 20∼300 g/L initial concentration. Cohesive sediment deposition and consolidation behaviours are as follows: cohesive sediment settlement can be divided into different stages as the initial free settlement and the consolidation settlement with different sediment interface rate. Cohesive sediment settlement influence factors are mainly the initial concentration and the settlement height, from which, settlement column size effect is determined by three factors as the wall effect, convection effect as well as the flocculation effect. During the final weight consolidation stage, deposited sediment consolidation settlement develops much faster than the excessive pore-pressure dissipation, and the fitted nonlinear consolidation constitutive relationship also can be obtained through deposited sediment layer sampling method. Results from this study indicate that the newly developed integrated settlement column system can effectively simulate the cohesive sediment suspension deposition and consolidation, and the nonlinear consolidation characteristics also can be studied through further experiments.

Numerical Simulation of Reinforcement Effect and Settlement of Concrete Pile Composite Foundation

The differential and large settlement may have a great effect on the construction and maintenance of highway. Based on the study of concrete pile composite foundation, the effect of concrete pile composite foundation on reinforcement and influence factors of settlement are analyzed in the paper. The effects of pile modulus and embankment modulus on settlement with numerical simulation method are analyzed in the paper. The result of numerical simulation method is that the settlement of embankment may be reduced with the method of concrete pile composite foundation and pile modulus may have a great effect and embankment modulus may have some effect on the settlement of embankment.

Finite Element Analysis of Deformation Characteristic for Weak Interlayer Foundation

In accordance with settlement observation data of weak interlayer foundation in The North China Plain, finite element model was made to analyze vertical settlement and horizontal deformation by MIDAS/GTS software. Then, Influence factors of subgrade settlement were studied through changing the fill height, crust layer thickness and compression modulus. The results show that crust layer has the board supporting and closing the substratum functions during the period of loading and a relatively short period after loading. The maximum horizontal deformation occurs in weak interlayer rather than the ground surface. The horizontal deformation increases generally with the increase of the fill height. When the crust layer thickness increase, its settlement grows larger and the settlement of soft soil layer has the decrease trend. The settlement of crust layer and weak layer is decreased with the compression modulus increase of crust layer. It explains that the shell effects of crust layer increase with the compression modulus increase of crust layer.

Evaluation of the settlement influence factors of shallow foundation by numerical analyses

Several empirical and analytical methods have been proposed to estimate the elastic settlement of shallow foundations based on the elastic continuum theory. Previous methods have been generally proposed for circular foundations, its approach of using equivalent diameter was found less reliable for foundations of aspect ratio L/B > 2. This paper presents a three-dimensional numerical analysis to extend and improve the applicability of settlement influence and correction factors for shallow foundations of large aspect ratios. First, a methodical optimization and verification program was conducted to determine and verify a reliable model for numerical analysis. Using the verified model, two new sets of settlement influence factor and correction factor for foundation roughness of circular and rectangular foundations were then derived and proposed. A correction factor chart for the foundation rigidity of rectangular foundations was also proposed. Finally, the applicability of the proposed factors in this study was verified by comparing calculated settlements using the proposed factors along with the measured values from two raft foundations. The proposed approach was indicated to be a better alternative for foundations of L/B > 2.

Analysis of the Influence Factors of Differential Settlement of High Embankment in Mountain Area

This paper reveals and analyses various influence factors which cause differential settlement of high embankment in mountain area using indoor consolidation test and field loading test. In this research, the actual stress characteristics of high embankment are simplified, stability compression value of stuffing with loads under lateral restricted conditions can be measured, e-p curves and p-s curves are drawn, we can calculate compression modulus as computation criteria to estimate the settlement of high embankment. The results indicate that unconsolidated flow of high embankment is the main factor to cause differential settlement of high embankment in mountain area. As the soil consolidated, compressive deformation and the strength gradually increase, the bearing capacity of the foundation is enhanced to reduce differential settlement of the post-construction of high embankment.

The Numerical Analysis of CFG Pile Technology in the Disposing Soft Foundation in GuangWu Expressway

The problem of disposing the soft soil foundation will appear inevitably during the construction of modem high way. There are many ways to dispose the soft foundation. One of those is CFG pile technology. Take the CFG pile technology in the GuangWu Expressway for example, the influence factors of embankment settlement were discussed in detai by numerical analysis, some useful conclusions are obtained from the computational results.