Displacement Of Pile Foundation Research Articles

Impact Study of Deep Foundations Construction of Inclined and Straight Combined Support Piles on Adjacent Pile Foundations

An inclined straight combination support pile can play a better role in deep foundation pit support, especially for the protection of adjacent structural pile foundations. We take a section of the construction of a deep foundation pit project in Wuhan City, Hubei Province as the research object. This paper studies the influence of inclined and straight combination support piles on the bending moment and displacement behavior of adjacent pile foundations during the construction of foundation pits under the influence of different factors such as distance from the excavation surface, pit angle effect, inclined pile tilt angle, pit depth to width ratio, and construction conditions on the adjacent pile foundation using a three-dimensional finite element model. According to the research results, as the distance from the excavation surface increases, the bending moment of the adjacent pile foundation decreases, and the closer the pile is to the foundation pit, the greater the horizontal displacement of the pile; the bending moment and displacement of the pile foundation are supported by the pit angle effect. Moreover, the pile bending moment increases with the increase of the pit depth–width ratio, and the maximum displacement point of the pile body gradually moves down from the middle of the pile body to the bottom of the pile foundation as the excavation depth of the pit increases. In addition, the minimum displacement of the adjacent pile foundation is at the top of the pile, and the maximum displacement is at the middle of the pile. Finally, compared with the static analysis, the whole process of dynamic simulation can reflect the dangerous working conditions in the project construction process, and make a more complete safety control construction plan for the project construction process.

Study on Bearing Capacity of Belled Uplift Piles in Soft Clay Area

The study on the bearing capacity characteristics of the belled uplift piles in soft clay foundation is of guiding significance for the type selection and bearing performance of the piles. A full-scale test on the uplift piles in soft clay was carried out in Qianhai District of Shenzhen. The test results show that the belled uplift piles are applicable to the soft clay. Compared with the equal section uplift piles, the Q–S curves are smoother, the ultimate bearing capacity can be increased by more than 50%, and the piles perform more stability in the later stage of the test. The displacement of pile foundation, the elongation of pile body and the rebound ratio of pile foundation are studied. The results show that the foundation with the belled uplift piles are applicable in the soft clay areas, and the small-angle belled uplift pile head suitable for the soft clay area is proposed, which is of great significance for the popularization and use of the belled uplift piles.

Effect of spalling thickness on transverse axial bearing capacity of pile foundation under different corrosion depths

The transverse and axial bearing characteristics of bridge pile foundation in salt marsh area are studied by numerical simulation. This paper mainly analyses the change of transverse and axial bearing characteristics of pile foundation caused by the change of spalling thickness of bridge foundation. The results show that the transverse and axial bearing capacity and displacement of pile foundation will be affected by the change of concrete spalling thickness under the condition of pile corrosion. When the peeling thickness is above 9.0cm, the transverse and axial bearing characteristics of pile foundation are obviously different with the change of corrosion depth of pile body. When the peeling thickness increases and the corrosion depth of the pile body is different, the negative displacement below the zero point of the first displacement of the pile body is continuously reduced, and the displacement curve above the first displacement zero point in the direction of the pile body begins to shift. When the peeling thickness reaches 15.0cm, the pile top displacement increases to 3.75mm. The research results are of great significance to the establishment of safety evaluation system of highway bridge pile foundation in alpine salt marsh area, and provide a basis for the structural design of highway bridge pile foundation in alpine salt marsh area.

Numerical Simulation Study on Lateral Displacement of Pile Foundation and Construction Process under Stacking Loads

Lateral displacement of pile foundation is crucial to the safety of an overall structure. In this study, a numerical simulation on the lateral displacement of pile foundation under stacking loads was conducted to determine its relation with different influencing factors. Simulation results demonstrated that stacking loads at the pile side mostly influence the lateral displacement of pile foundation. The lateral displacement of pile foundation increases by one order of magnitude when the stacking loads increase from 100 kPa to 300 kPa. Other influencing factors are less important than stacking loads. Lateral displacements of the pile body and at the pile top can be reduced effectively by increasing the deformation modulus of surface soil mass, reducing the thickness of soft soil, and expanding pile diameter. Our analysis indicates that a nonlinear relationship exists between the lateral displacement at the pile top and the pile diameter. The lateral resistance of the pile body can be enhanced by coupling the stacking load along piles and the axial force at the pile top. An actual large-scale engineering project was chosen to simulate the effects of postconstructed embankment on lateral displacement and axial force of bridge pile foundation under different construction conditions and to obtain the lateral displacement of the pile body and the negative frictional resistance caused by soft soil compression under stacking loads. On the basis of the calculated results, engineering safety and stability were evaluated, and a guide for the design and construction was proposed.

Observation of Ground Movement with Existing Pile Groups Due to Tunneling in Sand Using Centrifuge Modelling

In developing urban areas, there are unavoidable interactions between existing structures and new construction such as tunnelling through pre-existing pile foundations. An accurate prediction of the ground deformation due to tunnelling is necessary to assess potential damage to those existing structures. Two dimensional tunnelling model tests were carried out to study the movement of both soil surface and subsurface layers of dry Toyoura sand with two pile groups of different length at both sides of the tunnel. The model pile group has four piles with spacing and diameter ratio of 5. The tunnelling process was simulated by reducing the diameter of the model tunnel with initial diameter of 70 mm for various ground loss values at 100g centrifugal acceleration. The induced soil movement and displacement of pile foundation were observed using the particle image velocity technique and displacement transducers. The test cases were conducted at two different tunnel cover depth and diameter ratios (C/D = 1.5 and 2.5) and three different horizontal distances between the pile groups and the tunnel. Tunnel machine showed good agreement of soil movements with the results from real site construction at small ground loss ratios. The cases with the pile group induced larger maximum settlement in the vertical direction than the cases without piles. There was an effect of the pile groups on the ground movement at the location more than five times pile diameter away from the piles in the longitudinal direction.

Effect of EPB Shield Tunneling on Adjacent High Speed Railway Viaduct

Based on a project of subway constructed near elevated high speed railway, FEM method is adopted to analyze the effect of shield tunneling on the horizontal and vertical displacement of pile foundation of the viaduct as well as the pile caps on the condition that the nearest clear distance is 5m. The results show that with appropriate parameter control of shield tunneling, the effect of EPB shield tunneling on the displacement of piles in the three directions, i.e. horizontal displacement along and perpendicular to the longitudinal direction of the rail line and vertical displacement, is little. The same goes for the differential settlement between pile caps.