Responses of single piles to tunneling-induced soil movements in sandy ground

2007 ◽  
Vol 44 (10) ◽  
pp. 1224-1241 ◽  
Author(s):  
Kuo-Hui Chiang ◽  
Chung-Jung Lee
Keyword(s):  
Load Transfer ◽  
Bending Moment ◽  
Test Results ◽  
Axial Forces ◽  
Depth Ratio ◽  
Sandy Ground ◽  
Single Piles ◽  
Pile Settlement ◽  
Ground Loss ◽  
Soil Movements

The responses of single piles under various working loads to nearby tunneling were investigated using centrifuge model tests. First, the tunneling-induced soil movements and the tunnel stability in saturated sandy ground were examined. Two instrumented piles with penetration depths of 27 m were located either side of, and at various distances from, tunnels embedded at depths with various cover-to-diameter ratios, and used to measure the bending moments and axial forces at various depths for various ground loss ratios during tunneling simulations. The test results show that in the case of shallow tunneling near a long pile the unit skin frictions on the pile from the tunnel axis to an elevation of 1.5 tunnel diameters above the tunnel axis rapidly decrease with increases in the ground loss ratio. A significant degradation of the end bearing capacity results in a large settlement of the pile if the pile tip is near the tunnel. The depth ratio was found to be a significant influence on the bending moment profiles along the piles, but both the depth ratio and the working loads on the pile head determine the axial load profile and the pile settlement. A mechanism for pile load transfer during new tunneling is proposed to enable construction engineers to prevent structure failure in piles and excessive pile settlement.

scholarly journals Single Pile Settlement and Load Transfer Mechanism due to Excavation in Silty Clay

2018 ◽  
Vol 8 (1) ◽  
pp. 2485-2492 ◽  
Author(s):  
M. A. Soomro ◽  
K. F. Memon ◽  
M. A. Soomro ◽  
A. Memon ◽  
M. A. Keerio
Keyword(s):  
Load Transfer ◽  
Bending Moment ◽  
Small Strain ◽  
Transfer Mechanism ◽  
Ground Movement ◽  
Major Influence ◽  
Silty Clay ◽  
Single Pile ◽  
Load Transfer Mechanism ◽  
Pile Settlement

In densely built areas, development of underground transportation system often involves excavations for basement construction and cut-and-cover tunnels which are sometimes inevitable to be constructed adjacent to existing piled foundations. In order to gain new insights into single pile responses (i.e. settlement and load transfer mechanism) to an adjacent excavation in saturated silty clay, a three-dimensional coupled- consolidation numerical analysis is conducted in this study. An advanced hypoplasticity (clay) constitutive model with small-strain stiffness was adopted. A linear increase in pile settlement was observed due to excavation-induced stress release. This is because part of the pile is placed within the boundaries of a major influence zone due to excavation-induced ground movement. Based on a settlement criterion, apparent loss of pile‘s capacity is 14%. A maximum bending moment of about 350 kNm is induced in the pile with the maximum deflection of 28 mm. In addition, mobilisation of shear strength at the pile-soil interface was found to be a key factor governing pile-soil-excavation interaction. During excavation, a downward load-transfer mechanism in the piles can be identified.

scholarly journals Driven Pile Effects on Nearby Cylindrical and Semi-Tapered Pile in Sandy Clay

2021 ◽  
Vol 11 (7) ◽  
pp. 2919
Author(s):  
Massamba Fall ◽  
Zhengguo Gao ◽  
Becaye Cissokho Ndiaye
Keyword(s):  
Coupling Effect ◽  
Lateral Displacement ◽  
Bending Moment ◽  
Adaptive Mesh ◽  
Pile Driving ◽  
Arbitrary Lagrangian Eulerian ◽  
Axial Forces ◽  
Tapered Pile ◽  
Driven Pile ◽  
The Impact

A pile foundation is commonly adopted for transferring superstructure loads into the ground in weaker soil. They diminish the settlement of the infrastructure and augment the soil-bearing capacity. This paper emphases the pile-driving effect on an existing adjacent cylindrical and semi-tapered pile. Driving a three-dimensional pile into the ground is fruitfully accomplished by combining the arbitrary Lagrangian–Eulerian (ALE) adaptive mesh and element deletion methods without adopting any assumptions that would simplify the simulation. Axial forces, bending moment, and lateral displacement were studied in the neighboring already-installed pile. An investigation was made into some factors affecting the forces and bending moment, such as pile spacing and the shape of the already-installed pile (cylindrical, tapered, or semi-tapered). An important response was observed in the impact of the driven pile on the nearby existing one, the bending moment and axial forces were not negligible, and when the pile was loaded, it was recommended to consider the coupling effect. Moreover, the adjacent semi-tapered pile was subjected to less axial and lateral movement than the cylindrical one with the same length and volume for taper angles smaller than 1.0°, and vice versa for taper angles greater than 1.4°.

Experimental study of moment carrying behavior of typical Tibetan timber beam-column joints

2021 ◽  
pp. 136943322110015
Author(s):  
Ting Guo ◽  
Na Yang ◽  
Huichun Yan ◽  
Fan Bai
Keyword(s):  
Bending Moment ◽  
Structural Performance ◽  
Test Results ◽  
Timber Beam ◽  
Rotational Stiffness ◽  
Trilinear Model ◽  
Column Joint ◽  
Loading Tests ◽  
The Moment ◽  
Relationship Of

This study aimed to investigate the moment carrying behavior of typical Tibetan timber beam-column joints under monotonic vertical static load and also evaluate the influence of length ratio of Gongmu to beam (LRGB) and dowels layout on the structural performance of the joint. Six full-scale specimens were fabricated with same construction but different Gongmu length and dowels position. The moment carrying performance of beam-column joints in terms of failure mode, moment resistance, and rotational stiffness of joints were obtained via monotonic loading tests. Test results indicated that all joints are characterized by compressive failure perpendicular to grain of Ludou. Additionally, it was found that greater LRGB leads to greater initial rotational stiffness and maximum moment of the joint by an increase of restraint length for beam end; however, offsetting dowels toward column resulted smaller stiffness and ultimate bending moment of joints, particularly, offsetting Beam-Gongmu dowels toward column changed the moment-rotation curve pattern of the beam-column joint, accompanied by a hardening stiffness at last phase. Furthermore, a simplified trilinear model was proposed to represent the moment-rotation relationship of the typical Tibetan timber beam-column joint.

scholarly journals Influence of stirrup spacing on shear resistance and deformation of reinforced concrete beams

2018 ◽  
Vol 7 (1) ◽  
pp. 126
Author(s):  
Latha M S ◽  
Revanasiddappa M ◽  
Naveen Kumar B M
Keyword(s):  
Concrete Beam ◽  
Concrete Beams ◽  
Bending Moment ◽  
Maximum Load ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Cement Concrete ◽  
Simply Supported ◽  
Reinforced Cement ◽  
Flexural Reinforcement

An experimental investigation was carried out to study shear carrying capacity and ultimate flexural moment of reinforced cement concrete beam. Two series of simply supported beams were prepared by varying diameter and spacing of shear and flexural reinforcement. Beams of cross section 230 mm X 300 mm and length of 2000 mm. During testing, maximum load, first crack load, deflection of beams were recorded. Test results indicated that decreasing shear spacing and decreasing its diameter resulted in decrease in deflection of beam and increase in bending moment and shear force of beam.

Reliability analysis of drilled piers in expansive soils

1991 ◽  
Vol 28 (6) ◽  
pp. 834-842 ◽  
Author(s):  
Carlos Ferregut ◽  
Miguel Picornell
Keyword(s):  
Probabilistic Models ◽  
Load Transfer ◽  
Expansive Soils ◽  
Free Field ◽  
Expansive Soil ◽  
Maximum Tensile Stress ◽  
Limit States ◽  
Tensile Stresses ◽  
Head Displacement ◽  
Soil Movements

Heavy structures in areas with expansive soils are commonly founded on piers resting beneath the surface active zone. During construction, the piers remain essentially unloaded and are exposed to potentially high tensile stresses that can split the pier unless the pier has been adequately reinforced. In this context, uncertainties arise relative to (i) the parameters governing the load transfer from the soil to the pier, (ii) the potential heave to be expected in a "free field" condition, when the soil movements are not restricted by the pier, and (iii) the estimation of the pier capacity to resist the induced stresses. Probabilistic models to handle and to quantify these uncertain parameters are constructed and then used to compute the probability of exceeding two potential limit states: (i) vertical pier head displacement and (ii) maximum tensile stress in a cross section of the pier. The displacements are used to assess the serviceability performance of the pier, and the maximum tensile stresses are used to estimate the reliability of the pier. Key words: piers, expansive soil, reliability, probability, foundations.

Mechanical Behaviour of Steel-Concrete Twin I-Girder Bridges

2018 ◽  
Author(s):  
Weiwei Lin ◽  
Heang Lam ◽  
Teruhiko Yoda
Keyword(s):  
Load Transfer ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Test Results ◽  
Loading Test ◽  
Girder Bridges ◽  
Bridge Model ◽  
Symmetrical Loading ◽  
Unsymmetrical Loading ◽  
Girder Bridge

<p>Steel-concrete composite twin I-girder bridges have been built a lot in both Europe and Japan, but the lack of redundancy has always been a concern in U.S. and many other countries. In addition, few experimental studies have been performed on the mechanical performance of such bridges, particularly for the intact bridges. On this background, a steel-concrete composite twin I-Girder bridge model was designed according to the current highway bridge design specification in Japan and tested in the laboratory. The static loading tests were performed, and two loading conditions including both symmetrical loading and unsymmetrical loading were applied. Load versus deflection relationships were measured in the loading test, and the failure mode of the test specimen was discussed. The flexural strain development on bottom flanges of two main girders was also reported in this paper to confirm the load transfer between two main girders. In addition, the theoretical results on the basis of the classic theory were also provided to compare with the test results. The comparison indicates that the theoretical analyses can predict the behaviour of the twin I-girder bridges very well in the elastic stage by considering the effective width of the slab. The load transfer paths in such bridges were also discussed on the basis of the test results under un-symmetrical loading.</p>

Transversely Loaded Framework Members

1935 ◽  
Vol 39 (296) ◽  
pp. 718-749 ◽  
Author(s):  
N. J. Hoff
Keyword(s):  
Standard Method ◽  
Bending Moment ◽  
Strength Calculation ◽  
Aircraft Fuselage ◽  
Axial Forces ◽  
External Forces

The standard method of strength calculation of a framework is based on the assumption that members are freely pinned together and external forces are applied only at nodes. Actually aircraft fuselage members are stiffly joined and transverse forces are often acting on them at considerable distances from nodes, e.g., weights of crew, instruments and oil, reactions of controls, stabiliser adjusting gear, etc.The safest method of computing stress in such members is to assume both ends pin—jointed. As they actually are stiffly connected to adjacent members, they are not allowed to twist freely, i.e., the truss exerts moments on the loaded member. The effect of these end moments consists in diminishing deflection andfield moments. The decrease of maximum bending moment may attain nearly 50 per cent.Since framework members are designed to withstand axial forces only, viz., tension or compression, they are comparatively weak against bending and have to be strengthened appreciably if transverse forces are present.

scholarly journals An Investigation into the Effect of Cracking on the Response of Drilled and Postgrouted Concrete Pipe Pile under Lateral Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Zhijun Yang ◽  
Qing Fang ◽  
Bu Lv ◽  
Can Mei ◽  
Xudong Fu
Keyword(s):  
Flexural Rigidity ◽  
Bending Moment ◽  
Test Results ◽  
Lateral Loads ◽  
Analysis Method ◽  
Pile Head ◽  
Laterally Loaded Piles ◽  
Pipe Pile ◽  
Concrete Pipe ◽  
Laterally Loaded

The cracks are likely to initiate on a lateral loaded pile and would cause greater deflection at the pile head. However, there is a lack of thorough investigation into the effect of cracking on the response of the lateral loaded pile. In this article, a full-scale field test was carried out to investigate the behavior of Drilled and Postgrouted Concrete Pipe Pile under lateral loads. A novel analysis method for the lateral loaded pile, which can take the cracking effects into consideration, was proposed, and the validity was verified by the test results. With the proposed method, the cracking effects on flexural rigidity, displacement, rotation, and bending moment of the pile were studied. In brief, cracking effect would dramatically reduce the flexural rigidity of the pile, remarkable increase the displacement and rotation of the pile top, and slightly decrease bending moment of the pile. Unambiguously, the results show that the proposed method can excellently predict the response of laterally loaded piles under cracking effects.

scholarly journals On Flexural Performance of Girder-To-Girder Wet Joint for Lightweight Steel-UHPC Composite Bridge

2020 ◽  
Vol 10 (4) ◽  
pp. 1335 ◽  
Author(s):  
Shuwen Deng ◽  
Xudong Shao ◽  
Banfu Yan ◽  
Yan Wang ◽  
Huihui Li
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Bending Moment ◽  
Inhibitory Effect ◽  
Careful Consideration ◽  
Joint Interface ◽  
Test Results ◽  
Negative Moment ◽  
Composite Bridge ◽  
Negative Bending

Joints are always the focus of the precast structure for accelerated bridge construction. In this paper, a girder-to-girder joint suitable for steel-ultra-high-performance concrete (UHPC) lightweight composite bridge (LWCB) is proposed. Two flexural tests were conducted to verify the effectiveness of the proposed T-shaped girder-to-girder joint. The test results indicated that: (1) The T-shaped joint has a better cracking resistance than the traditional I-shaped joint; (2) The weak interfaces of the T-shaped joint are set in the areas with relatively lower negative bending moment, and thus the cracking risk could be decreased drastically; (3) The natural curing scheme for the joint is feasible, and the reinforcement has a very large inhibitory effect on the UHPC material shrinkage; The joint interface is the weak region of the LWCB, which requires careful consideration in future designs. Based on the experimental test results, the design and calculation methods for the deflection, crack width, and ultimate flexural capacity in the negative moment region of LWCB were presented.

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.

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