scholarly journals STUDY OF THE INFLUENCE OF A BORED PILE DIAMETER ON CHANGE OF COEFFICIENT OF SUBGRADE REACTION AT CALCULATION FOR HORIZONTAL LOADS

2019 ◽  
Vol 9 (4) ◽  
pp. 11-15
Author(s):  
Airat Z. GAISIN ◽  
Sergey A. KRUTYAEV ◽  
Anton O. GLAZACHEV
Keyword(s):  
Large Diameter ◽  
Three Dimensional ◽  
Bending Moment ◽  
Soil Conditions ◽  
Subgrade Reaction ◽  
Pile Head ◽  
Bored Pile ◽  
Pile Diameter ◽  
Numerical Studies ◽  
Bored Piles

The problem of designing foundations using long bored piles of large diameter is shown. Such piles are most often used in the construction of buildings and structures, on the foundations of which large loads are transferred, and such buildings are often built on sites with difficult soil conditions. When designing foundations using such piles, it becomes necessary to calculate them for horizontal load and bending moment. The article is devoted to studies of the dependence of the coefficient of subgrade reaction on the diameter of piles when calculating long bored piles of large diameter in clay soils. To determine the patt erns of changes in the coefficient of subgrade reaction from the diameter of the piles, numerical studies in a three-dimensional setting were performed. Based on the results obtained, the graphs «load - displacement» are constructed. The method of calculating the coefficient of subgrade reaction with known movements of the pile head and the applied load is shown. The regularities of changes in the deformability of the soil base with an increase in the diameter of the pile are revealed and a coefficient taking into account this dependence is proposed.

scholarly journals Study on the horizontal bearing characteristics of pile foundation in coral sand

2021 ◽  
Author(s):  
Chunyan Wang ◽  
Hanlong Liu ◽  
Xuanming Ding ◽  
Chenglong Wang ◽  
Qiang Ou
Keyword(s):  
Lateral Displacement ◽  
Experimental Studies ◽  
Deformation Characteristic ◽  
Bending Moment ◽  
Silica Sand ◽  
Pile Head ◽  
Pile Diameter ◽  
Coral Sand ◽  
Horizontal Pressure ◽  
Different Diameters

This paper presents the horizontal bearing characteristics of piles in coral sand and silica sand from comparative experimental studies. A total of 6 model piles with different diameters are tested. The horizontal bearing capacity, deformation characteristic, bending moment, p-y curve, the change in soil horizontal pressure, as well as the particle breakage behaviour of coral sand are investigated. The results show that, in coral sand foundation, the horizontal bearing capacities of piles and the increments of soil horizontal pressures are obviously greater than those in silica sand. Accordingly, the lateral displacement, the rotation of pile head, the bending moment and the corresponding distribution depth in coral sand are significantly smaller than that in silica sand. The p-y curves indicate that the horizontal stiffness of coral sand is greater than that of silica sand. Remarkably, the breakage behaviour of coral sand is mainly distributed in the range of 10 times pile diameter depth and 5 times pile diameter width on the side where the sand is squeezed by pile. Furthermore, in coral sand, the influence of pile size is more pronounced, the squeezing force generated by pile spread farther and its influence range is larger compared to those in silica sand.

Three-Dimensional Numerical Analyses of Pile Response due to Braceded Excavation-Induced Lateral Soil Movement

2014 ◽  
Vol 580-583 ◽  
pp. 524-531 ◽  
Author(s):  
Lin Li ◽  
Xiao Xin Hu ◽  
Guang Hui Dong ◽  
Ju Liu
Keyword(s):  
Lateral Displacement ◽  
Three Dimensional ◽  
Bending Moment ◽  
Elastic Behavior ◽  
Pile Head ◽  
Soil Pressure ◽  
Soil Movement ◽  
Standard Problem ◽  
Modified Cam Clay ◽  
Pile Response

Using the explicit finite difference code FLAC3D, the behavior of pile adjacent to braced excavation is investigated. The Modified-cam clay constitutive model was employed to model the non-linear stress-strain soil behavior, and the pile was assumed to have linear elastic behavior. The interface model incorporated in FLAC3D code was used to simulate the soil/pile contact, The built-in 'fish' language was used to calculate the data demanded. The pile response such as pile deflection, bending moment and lateral soil pressure were studied, and it is shown that the pile response is different from that caused by the excavations which are unstructted. In "standard" problem, the effect of different pile head constraints on the pile response was investigated, the effect of lateral displacement of the wall, distance from the excavation face, pile stiffness, pile length and axial load on the pile response are also investigated when the pile head is constrained from deflection. The research finding was compared with other published case history and reasonably good agreement was found between them.

scholarly journals Investigating the Effect of Geocell Changes on Slope Stability in Unsaturated Soil

2020 ◽  
Vol 14 (1) ◽  
pp. 66-75
Author(s):  
Behnam Mehdipour ◽  
Hamid Hashemolhosseini ◽  
Bahram Nadi ◽  
Masoud Mirmohamadsadeghi
Keyword(s):  
Slope Stability ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Bending Strength ◽  
Load Capacity ◽  
Three Dimensional ◽  
Bending Moment ◽  
Soil Conditions ◽  
Vertical Side ◽  
Basic Model

The purpose of this research is to investigate the performance and efficiency of reinforced slope in the stability of geocell layers in unsaturated soil conditions. Slope reinforced with geocell acts like a beam in the soil due to the geocell having a height (three-dimensional). Due to its flexural properties, it has moment of inertia as well as bending strength, which reduces the displacement and increases the safety factor of the slope. Taking into consideration unsaturated conditions of soil contributes a lot to making results close to reality. One of the well-known models among elastoplastic models for modeling unsaturated soils is Barcelona Basic Model, which has been added to the FLAC2D software by codification. Changes in thickness, length and number of geocell layers are remarkably effective on slope stability. The results show that the geocell's reinforcing efficiency depends on the number of layers and depth of its placement. As the depth of the geocell's first layer increases, the lateral and vertical side elevation of the upper part of the slope increases with respect to the elevation. Load capacity increases with increasing geocell length. By increasing the length of the geocell layer, the joint strength, the mobilized tensile strength, and the bending moment are increased. At u/H = 0.2, an increase in the bending momentum of about 20% occurs with increasing geocell thickness. In u/H = 1, the increase in bending momentum is 10.4%. In addition, by increasing the thickness of the geocell, the Value of moment of the inertia increases and, as a result, the amount of geocell reinforcement bending moment increases.

scholarly journals Monopile foundation under lateral cyclic action. Numerical modelling

2019 ◽  
Vol 85 ◽  
pp. 08008
Author(s):  
Andrei Valentin Drăguşin ◽  
Loretta Batali
Keyword(s):  
Numerical Model ◽  
Numerical Modelling ◽  
Numerical Models ◽  
Lateral Displacement ◽  
Large Diameter ◽  
Bending Moment ◽  
Small Scale ◽  
Design Elements ◽  
Pile Diameter ◽  
Starting Point

Foundation of an off-shore wind mill is submitted throughout its existence to a very high number of cycles coming from lateral actions such as waves or wind. These actions have a strong aleatory character which makes them very hard to predict, quantify and analyse. Therefore, in current design practice, these actions are being considered as pseudo-static force at their maximum values, with the cyclic phenomenon being neglected. This can lead to an inappropriate design of the foundation, which could have a negative impact on the future structure. This type of structure is generally built on a monopile foundation, a single, large diameter pile, which will be submitted to thousands lateral cycles. The pile diameter plays an important role, influencing the behaviour of the entire structure. Centrifuge experiments on small-scale models are very useful to study such complex problem as piles under lateral cyclic loads. Several researches have been carried out internationally and the results can be used for calibrating numerical models, which is obviously a more accessible method of design, compared to an experimental approach. This has been precisely the starting point of this paper. The purpose of the present paper is to analyse the influence of the pile diameter, by using a FEM a numerical model, previously calibrated based on centrifuge experiments carried out at IFSTTAR Nantes. For the numerical modelling the software CESAR-LCPC 3D has been used. Several pile diameters have been considered, as follows: 0.72 m, 1.08 m, 1.44 m, 1.80 m, 2.16 m and 2.52 m. The results are taking into account the lateral displacement and bending moment of the piles, for static and cyclic loading. The main objective was to determine the stabilisation rate of the most important two design elements (pile head displacement and maximum bending moment) after “n” cycles and to eventually conclude the diameter value beyond which no more influence of cycles is recorded. The numerical model considered 15 cycles and the results have been used extrapolated in order to determine the cycle “n” of stabilisation (for displacement and bending moment).

scholarly journals Accuracy and precision of the CSLT measurement system: An experiment to defect diagnoses in bored piles

2021 ◽  
Vol 28 (4) ◽  
pp. 176-185
Author(s):  
Zezhong Wang ◽  
Eric Tak Cho Ho ◽  
Inez Maria Zwetsloot
Keyword(s):  
Hong Kong ◽  
Measurement System ◽  
Measurement Accuracy ◽  
Large Diameter ◽  
Housing Projects ◽  
Bored Pile ◽  
Accuracy And Precision ◽  
Bored Piles ◽  
Pile Type ◽  
Sonic Logging

A new measurement system called Crosshole Sonic Logging Tomography (CSLT) provides information on the size, shape, and orientation of defects in a bored pile. The CSLT measurement system has not (yet) been accredited in Hong Kong for foundation testing. Bored piles in Hong Kong are generally wide and deep. Existing measurement accuracy studies do not consider this large type of bored piles. The objective of this research is to quantify the measurement accuracy and precision of the CSLT method for large diameter bored piles (the most common pile type for public housing projects in Hong Kong). A test pile was constructed with known defects and perform experiments with a CSLT measurement system to quantify its accuracy and precision. CSLT is found to be accurate in detecting shape, size, and location of large defects but small defects close to the tube are difficult to detect. Generally speaking, CSLT has satisfactory accuracy and precision for practical use. The use of CSLT can be considered as a feasible method in defect diagnosis of bore piles in Hong Kong.

scholarly journals Numerical Analysis of Large Diameter Bored Pile Installed in Multi Layered Soil: A Case Study of Damietta Port New Grain Silos Project

2018 ◽  
Vol 8 (02) ◽  
Author(s):  
M. Eid ◽  
A. Hefny ◽  
T. Sorour ◽  
Y. Zaghloul ◽  
M. Ezzat
Keyword(s):  
Clayey Soil ◽  
Large Diameter ◽  
Element Model ◽  
Layered Soil ◽  
Soil Parameters ◽  
Loading Test ◽  
Dilatancy Angle ◽  
Soil Layers ◽  
Bored Pile ◽  
Pile Diameter

A finite element model is established using MIDAS GTS NX 2018 software, in order to simulate the behavior of an instrumented large diameter bored pile, installed in multi layered soil and tested under three different loading and unloading cycles at Damietta Port Grain Silos project site. Modified Mohr-Coulomb constitutive model has been used to define the drained condition for sandy soil layers and undrained condition for clayey soil layers. Necessary soil parameters were determined from extensive laboratory and in-situ soil tests. Numerical results are compared with field loading test measurements and very good agreement is obtained. The effect of dilatancy angle on pile load transfer mechanism was investigated, and results of the study showed important effect for the dilatancy angle on the pile settlement values and the load distribution along the pile shaft. Results obtained also showed that the plastic zone below the base of the pile at failure extended laterally to about seven times the pile diameter and vertically to about 5 times the pile diameter.

scholarly journals Method to Control the Deformation of Anti-Slide Piles in Zhenzilin Landslide

2020 ◽  
Vol 10 (8) ◽  
pp. 2831 ◽  
Author(s):  
Hao Wang ◽  
Peng Wang ◽  
Hongyu Qin ◽  
Jianwei Yue ◽  
Jianwei Zhang
Keyword(s):  
Shear Force ◽  
Slip Surface ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Subgrade Reaction ◽  
Pile Head ◽  
Landslide Stability ◽  
Subsequent Decrease ◽  
Maximum Shear Force ◽  
Internal Forces

Anti-slide piles were used in the region of the Zhenzilin landslide in Sichuan, China. The horizontal displacement of these piles exceeds specifications. Deterioration in bedrock properties may cause deformation, thereby causing landslide destabilization. An approach was developed for the analysis of anti-slide pile in two bedrocks with different strengths below the slip surface. A relationship has been established between the modulus of subgrade reaction of the first weak bedrock and reasonable embedded length for landfill slopes with strata of various strengths. Furthermore, the influence of embedding length on deformation has been studied to determine the reasonable embedded length, which helps reduce deformation and ensure landslide stability. The results reveal that (1) at a constant embedded length, horizontal displacement increases with the thickness of the first soft bedrock, meanwhile the maximum shear force remains constant, and the bending moment first increases followed by subsequent decrease; (2) with an increase in the embedded length, horizontal displacement and the maximum shear force of the pile in the embedded bedrock decrease, whereas the bending moment increases; (3) the maximum internal forces and horizontal displacement increase with a decrease in the subgrade reaction modulus of the first weak rock; and (4) the reasonable embedded length of an anti-slide pile increases with a decrease in the subgrade reaction modulus of the first weak bedrock. The proposed approach can be employed to design anti-slide piles in similar landslide regions to control pile-head deformation.

scholarly journals Potential and prospects of photocatalytic disinfection: using sustainable solarenergy- driven photocatalysts

2021 ◽  
Vol 28 (4) ◽  
pp. 165-175
Author(s):  
Juhua He ◽  
Kenny W K Hui ◽  
Irene M C Lo
Keyword(s):  
Hong Kong ◽  
Measurement System ◽  
Measurement Accuracy ◽  
Large Diameter ◽  
Housing Projects ◽  
Bored Pile ◽  
Accuracy And Precision ◽  
Bored Piles ◽  
Pile Type ◽  
Sonic Logging

A new measurement system called Crosshole Sonic Logging Tomography (CSLT) provides information on the size, shape, and orientation of defects in a bored pile. The CSLT measurement system has not (yet) been accredited in Hong Kong for foundation testing. Bored piles in Hong Kong are generally wide and deep. Existing measurement accuracy studies do not consider this large type of bored piles. The objective of this research is to quantify the measurement accuracy and precision of the CSLT method for large diameter bored piles (the most common pile type for public housing projects in Hong Kong). A test pile was constructed with known defects and perform experiments with a CSLT measurement system to quantify its accuracy and precision. CSLT is found to be accurate in detecting shape, size, and location of large defects but small defects close to the tube are difficult to detect. Generally speaking, CSLT has satisfactory accuracy and precision for practical use. The use of CSLT can be considered as a feasible method in defect diagnosis of bore piles in Hong Kong.

DYNAMIC ANALYSIS OF OFFSHORE PILES EMBEDDED IN ELASTOPLASTIC SOFT CLAY

2016 ◽  
Vol 3 (2) ◽  
Author(s):  
Anis Mohamad Ali ◽  
Mohamad J. K. Essa ◽  
Abdulameer Qasim Hassan
Keyword(s):  
Soft Clay ◽  
Three Dimensional ◽  
Bending Moment ◽  
Pile Head ◽  
Finite Element Program ◽  
Head Displacement ◽  
Element Program ◽  
Pile Length ◽  
Elastoplastic Soil ◽  
Offshore Piles

This work deals with the dynamic behavior of offshore piles embedded in soft clay, and an attempt is made to estimate the critical embedded pile length. ABAQUS finite element program is used to simulate the problem. The soil was modeled as an elastic state and elastoplastic state and represented by cam-clay model. Three dimensional elements were used to represent the interaction between pile and soil, laboratory tests are used to obtain the real properties of soil and to describe interface. The results obtained are used to develop the elastic equation used by Matlock and Reese to calculate the critical embedded pile length for pile embedded in elastoplastic soil. Also, show that the critical embedded pile length is increased by about (20 % to 40 %) due to changing soil model from elastic to elastoplastic. The pile embedded in an elastoplastic soil is dependent on soil strength, interface properties and pile rigidity. The pile head displacement is increased about 90 % while the bending moment is deceased by 10 % at pile head.

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