Design of reinforcing piles to increase slope stability

1995 ◽  
Vol 32 (5) ◽  
pp. 808-818 ◽  
Author(s):  
Harry G. Poulos
Keyword(s):  
Shear Force ◽  
Soil Mechanics ◽  
Relative Depth ◽  
Soil Movement ◽  
Pile Diameter ◽  
Maximum Shear Force ◽  
Final Design ◽  
Length Step ◽  
Pile Interaction ◽  
Pile Length

This paper describes an approach for the design of piles to reinforce slopes, involving three main steps: (1) evaluating the shear force needed to increase the safety factor to the desired value; (2) evaluating the maximum shear force that each pile can provide to resist sliding of the potentially unstable portion of the slope; and (3) selection of the type and number of piles, and the most suitable location of these piles within the slope. For step 1, stability analyses can be used to assess the required additional shear force for stability. Step 2 involves the use of a computer analysis for the response of a pile to laterally moving soil. This analysis can be implemented via a computer program ERCAP, and enables the resisting shear force developed by the piles to be evaluated as a function of pile diameter and flexibility and the relative depth of the soil movement in relation to the pile length. Step (3) involves the use of engineering judgement in conjunction with the analysis results from steps 1 and 2. The paper describes the ERCAP analysis and the characteristics of pile behaviour it reveals. The application of the approach to a highway bypass problem in Newcastle, Australia, is described in detail. In the final design, a total of 64 bored piles 1.2 m in diameter were used over a total length of slope cutting of about 250 m. The pile lengths ranged between 6 and 12 m, with the spacings varying between 3.2 and 6.0 m. Key words : analysis, boundary element, piles, soil–pile interaction, slope stabilization, soil mechanics.

scholarly journals Assessing the effect of governing parameters of bearing capacity determination of small piled rafts on clay soil

2021 ◽  
Vol 14 (22) ◽  
Author(s):  
Shivanand Mali ◽  
Baleshwar Singh
Keyword(s):  
Shear Force ◽  
Bending Moment ◽  
Pile Spacing ◽  
Piled Raft ◽  
Pile Diameter ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Maximum Shear Force ◽  
Settlement Ratio ◽  
Pile Length

Abstract In the present study, a small piled raft foundation has been simulated numerically through PLAXIS 3-D software. The objective of this study was to investigate the effect of governing parameters such as pile length, pile spacing, pile diameter, and number of piles on the settlement and load-bearing behavior of piled raft, so as to achieve the optimum design for small piled raft configurations. An optimized design of a piled raft is defined as a design with allowable center and differential settlements and satisfactory bearing behavior for a given raft geometry and loading. The results indicated that, with increase in pile length, pile spacing, pile diameter, and number of piles, both the center settlement ratio and differential settlement ratio decreased. The load-bearing capacity of piled raft increased with increase in pile length, pile spacing, pile diameter, and number of piles. Furthermore, the percentage load carried by the piles increased as the pile length, pile spacing, pile diameter, and number of piles increased. The bending moment and shear force in corner pile are noted to be more, and they decreased towards the center pile. With increase in pile length, the maximum raft bending moment decreased, whereas the maximum shear force in the raft increased. Further, with increase in pile spacing, pile diameter, and number of piles, the maximum bending moment and maximum shear force in the raft increased. The optimum parameters for the piled raft foundation can be selected efficiently with the consideration of maximum bending moment and maximum shear force while designing the piled raft foundation. Thus, the results of this study can be used as guidelines for achieving optimum design for small piled raft foundation.

Piled Raft Structure Finite Element Analysis of Composite Foundation Settlement in Da XI Passenger Dedicated Line

2014 ◽  
Vol 937 ◽  
pp. 438-443
Author(s):  
Xiao Tong Ma ◽  
Guang Long Liu
Keyword(s):  
Finite Element ◽  
Composite Foundation ◽  
Foundation Settlement ◽  
Pile Spacing ◽  
Finite Element Software ◽  
Piled Raft ◽  
Pile Diameter ◽  
Foundation Treatment ◽  
Pile Length ◽  
Passenger Dedicated Line

Composite foundation settlement of piled raft structure in Da Xi passenger dedicated line is analyzed by the large finite element software MIDAS/GTS and established calculation model of foundation treatment. The problem of pile-soil contact is highlighted in the trail and analyzes the settlement nephogram and pile-soil stress nephogram. On this basis the foundation settlement factors was analyzed systematically that focus on the elastic modulus of pile, pile spacing, pile diameter and pile length in foundation treatment, especially for the characteristics parameters of contact element. Result shows that increasing the pile modulus, pile diameter, pile length and decreasing the pile spacing is all conducive to reducing settlement. The best advice is got that the pile diameter should be not more than 0.5m, pile length not more than 27m and the pile spacing be around 2m.

The Calculation of Critical Pile Length for Super-Long Pile Based on Settlement Control

2011 ◽  
Vol 71-78 ◽  
pp. 4179-4183
Author(s):  
Li Nong Xia ◽  
Yun Dong Miao ◽  
Tie Qiang Tan ◽  
Xin Tong
Keyword(s):  
Shear Deformation ◽  
Field Measurement ◽  
Load Transfer ◽  
Working Condition ◽  
Transfer Model ◽  
Shaft Resistance ◽  
Pile Diameter ◽  
Pile Settlement ◽  
Deformation Transfer ◽  
Pile Length

Based on the analysis of character of load-transfer of super-long pile, for the purpose of pile settlement control, critical pile length for single friction super-long pile was calculated by Cooke’s shear deformation-transfer model, because the assumption of Cooke’s model is similar with working condition of super-long pile. In the analysis, compression of pile is taken into account. Then, the design chart of critical pile length for super-long pile is provided for normal design index. Lastly, the critical pile length of an engineering example is analysed by the method, the calculated results have agreed well with the field measurement. The analysis show that critical pile length is greatly concerned with ratio of Young’s module of pile and soil, the greater the ratio is, longer the critical pile length is. Pile diameter also affects the critical pile length, the larger the diameter is, longer the critical pile length is. In addition, the critical pile length of super-long pile is concerned with shaft resistance distribution along the pile.

Study of Structure and Properties of New Rolling-Cut Shear

2010 ◽  
Vol 146-147 ◽  
pp. 991-995
Author(s):  
Zhi Bing Chu ◽  
Qing Xue Huang ◽  
Zhi Yuan Zhang ◽  
Dan Li
Keyword(s):  
Theoretical Analysis ◽  
Shear Force ◽  
Motion Path ◽  
Negative Bias ◽  
Horizontal Force ◽  
Structure And Properties ◽  
Force Component ◽  
Shear Forces ◽  
Maximum Shear Force ◽  
Force Components

Based on rolling-cut shear simulation, using a kind of single-shaft and double eccentricity rolling-cut shear, which adopts a new structure of asymmetric feature and negative bias, as the calculating model by establishing motion path equation of spatial shear mechanism, comparing with the steel shear forces, link forces and horizontal link force components with or without asymmetric feature, the asymmetric formulation is deduced. Such asymmetric crank structure can decrease horizontal force component between the linkages during rolling-cut process, increase the effective drive force on links while it comes to the maximum shear force, and decrease the extrusion of blade arc on steel edge as well. Theoretical analysis and steel-shearing quality at site indicate that asymmetric and negative bias is an important and efficient way to prolong the lifetime of blade, decrease blade wear, improve shearing quality, and maintain the constant clearance between blades.

The Influence of Engineering Pile on the Bottom Upheaval of Foundation Pit

2012 ◽  
Vol 193-194 ◽  
pp. 624-632
Author(s):  
Xi Zhen Zhang ◽  
Quan Mei Gong ◽  
Shun Hua Zhou
Keyword(s):  
Element Model ◽  
Correction Method ◽  
Inhibitory Effect ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Pile Spacing ◽  
Deformation Control ◽  
Pile Diameter ◽  
Pile Length

In foundation pit engineering, the presence of pile plays an important role on the pit stability and deformation control. The bottom upheaval of deep foundation pit is a key criterion of judging the foundation stability and deformation. This paper built the 3D finite element model to analyze the influence of different factors (pile diameter, pile length and pile spacing) on the bottom upheaval, and concluded that: when pile length and pile spacing is constant, changing the pile diameter can hardly affect the bottom upheaval; as the pile length increased, the inhibitory effect to the bottom upheaval grew stronger with a gradually decreased growth rate; increasing pile spacing can significantly reduce the bottom upheaval, and the smaller the pile spacing, the smaller the upheaval. The concept of upheaval inhibition rate was defined to evaluate the influence of different factors of pile layout on the bottom upheaval. A correction method of calculating the bottom upheaval of foundation pit with engineering pile was proposed. An engineering instance of Shanghai Natural History Museum foundation pit was studied, and the result showed that the bottom upheaval calculated by the correction method is less than the upheaval calculated by method of residual stress, which was more close to the monitoring data. The influence of engineering pile on bottom upheaval of foundation pit should not be neglected where a large number of piles were present in deep foundation pit.

scholarly journals An Experimental Study on Pile Spacing Effects under Lateral Loading in Sand

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Mahdy Khari ◽  
Khairul Anuar Kassim ◽  
Azlan Adnan
Keyword(s):  
Pile Group ◽  
Experimental Investigations ◽  
Pile Groups ◽  
Dense Sand ◽  
Spacing Effects ◽  
Pile Diameter ◽  
Lateral Resistance ◽  
Model Pile ◽  
Pile Interaction ◽  
Subgrade Modulus

Grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. Ultimate lateral resistance and lateral subgrade modulus within a pile group are known as the key parameters in the soil-pile interaction phenomenon. In this study, a series of experimental investigation was carried out on single and group pile subjected to monotonic lateral loadings. Experimental investigations were conducted on twelve model pile groups of configurations 1 × 2, 1 × 3, 2 × 2, 3 × 3, and 3 × 2 for embedded length-to-diameter ratiol/d= 32 into loose and dense sand, spacing from 3 to 6 pile diameter, in parallel and series arrangement. The tests were performed in dry sand from Johor Bahru, Malaysia. To reconstruct the sand samples, the new designed apparatus, Mobile Pluviator, was adopted. The ultimate lateral load is increased 53% in increasing ofs/dfrom 3 to 6 owing to effects of sand relative density. An increasing of the number of piles in-group decreases the group efficiency owing to the increasing of overlapped stress zones and active wedges. A ratio ofs/dmore than6dis large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.

Measured Soil-Pile Interaction for Small Diameter Piles Embedded in Granular Soil Subjected to Lateral Soil Movement

2012 ◽  
Author(s):  
Muhannad T. Suleiman ◽  
Anne Raich ◽  
Lusu Ni ◽  
William Kingston ◽  
Timothy W. Polson ◽  
...  
Keyword(s):  
Small Diameter ◽  
Granular Soil ◽  
Soil Movement ◽  
Pile Interaction ◽  
Lateral Soil Movement

Effect of consolidation on responses of a single pile subjected to lateral soil movement

2015 ◽  
Vol 52 (6) ◽  
pp. 769-782 ◽  
Author(s):  
L.Z. Wang ◽  
K.X. Chen ◽  
Y. Hong ◽  
C.W.W. Ng
Keyword(s):  
Soft Clay ◽  
Bending Moment ◽  
Coefficient Of Consolidation ◽  
Construction Period ◽  
Soil Movement ◽  
Centrifuge Tests ◽  
Short Period ◽  
Lateral Soil Movement ◽  
Pile Response ◽  
Pile Length

Given extensive research carried out to study pile response subjected to lateral soil movement in clay, the effect of consolidation on the pile–soil interaction is rarely considered and systematically investigated. For this reason, four centrifuge tests were conducted to simulate construction of embankment adjacent to existing single piles in soft clay, considering two typical drainage conditions (i.e., drained and undrained conditions) and two typical pile lengths (i.e., relatively long pile and short pile). The centrifuge tests were then back-analyzed by three-dimensional coupled-consolidation finite element analyses. Based on reasonable agreements between the two, numerical parametric studies were conducted to systematically investigate and quantify the influence of construction rate and pile length on pile response. It is revealed that by varying drainage conditions, the piles respond distinctively. When the embankment is completed within a relatively short period (cvt/d2 < 2, where cv, t, and d denote the coefficient of consolidation, construction period, and pile diameter, respectively), the pile located adjacent to it deforms laterally away from the embankment. Induced lateral pile deflection (δ) and bending moment reduce with construction period. On the contrary, embankment constructed within a relatively long period (cvt/d2 > 200) leads the pile to deform laterally towards the embankment, with δ and bending moment increases with construction period. By halving the length of pile embedded in the drained ground, the maximum induced bending moment (BMmax) was slightly reduced (by 23%). On the other hand, shortening the length of the pile in the undrained ground is much more effective in reducing BMmax, i.e., halving pile length resulting in 78% reduction in bending moment. A new calculation chart, which takes various drainage conditions and pile lengths into account, was developed for estimation of BMmax.

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