In Situ Study on Reinforced Effect of Silt by Ram-Compaction Gravel Pile with End Expansion

2012 ◽  
Vol 446-449 ◽  
pp. 3428-3431
Author(s):  
Chao Liang Ye ◽  
Huai Ping Feng ◽  
Yao Jun Liu

Ram-compaction gravel pile with end expansion is widely adopted in the treatment of silty clay foundations. In this paper, the bearing properties of rammed gravel pile reinforced foundations and soil between piles were investigated by use of static load tests and heavy-duty dynamic penetration test. It is demonstrated that the settlement curves (P-S curve) of ram-compaction gravel pile with end expansion reinforced foundation and soil between piles were monotonic, without turning point being observed. With the increases of pile length, the bearing capacity of pile increases. According to the experimental results from heavy dynamic penetration tests and static load test, the strength of soil between piles is improved, which also have effects on the elimination of the uneven settlements. Comparison the results between heavy-duty dynamic penetration tests and over-heavy dynamic penetration tests shows that the later one is suitable on testing of the soil properties between piles. In addition, from in-situ measurements of uplift deformation of different depths, it is found that uplift behavior occurs with depth more than 0.5m, whit largest uplift value of 21cm. The result provides a reference for the design and construction of rammed gravel pile reinforced foundation.

2021 ◽  
Vol 11 (1) ◽  
pp. 45-64
Author(s):  
Duong Hong Tham ◽  
Truong Nhu Manh

Nowadays, in situ tests have played a viable role in geotechnical engineering and construction technology. Besides lab tests conducted on undisturbed soil samples, many different kinds of in-situ tests were used and proved to be more efficient in foundation design such as pressuremeter PMT, cone penetration test CPT, standard SPT, etc. Among them, a standard penetration test (SPT for short) is easy to carry out at the site. For decades, it has proved reliable to sandy soil, but many viewpoints and opinions argued that the test was not appropriately applicable to cohesive soil because of scattered and dispersed data of SPT blow counts through different layers. This paper firstly studies how reliable the SPT data can predict the physical and mechanical properties; secondly, the soil strength is determined in terms of corrected N-SPT values, and finally the bearing capacity of a pile penetrating cohesion soil. By analyzing data from 40 boreholes located in 18 projects in Ho Chi Minh City, South VietNam, coefficients of determination between SPT numbers and physical and mechanical properties of different soil kinds are not the same: R2 = 0.623 for sand, =0.363 for sandy clay and =0.189 for clay. The spatial variability of soil properties is taken into account by calculating the scale of fluctuation θ=4.65m beside the statistically-based data in horizontal directions. Finally, the results from two theoretical approaches of predicting pile bearing capacity were compared to those of finite element program Plaxis 3D and static load test at site. Correlation between the capacity computed by using corrected N-values instead of soil strength and results of static load test has proved to be well suitable in evaluating the bearing capacity of driven and jack-in piles, particularly installing in the cohesive soil using the SPT blows.


2012 ◽  
Vol 256-259 ◽  
pp. 410-415 ◽  
Author(s):  
Kai Cheng Huo ◽  
Xu Qin ◽  
Huan Huan Yue

Combined with the uplift static load test of large-diameter steel pipe pile in Xiangshan Port bridge of Ningbo, make analysis of Q-s curve and s-lgt curve, axial force distribution curve and unit shaft resistance, revealing the uplift characteristic of the steel pipe pile. The analyses show that the uplift steel pipe pile is pure friction pile, the uplift load is decreased downward through the axial force of pile body, the shaft resistance gradually plays from top to bottom and play completely in the upper soil. Moreover, it has used hyperbolic model to fit the measured Q-s curve by Matlab software, and the fitting precision is high. Then make the hyperbolic model non-dimensional, and attempt to predict ultimate bearing capacity using the maximum curvature point of the non-dimensional hyperbolic model, to get some mechanical characteristic.


2016 ◽  
Vol 8 (5) ◽  
pp. 495-498
Author(s):  
Tautvydas Statkus

In this article jacked pile installation technology and its current processes, altering the base physical and mechanical characteristics are discussed. For the jacked pile static load test simulation Plax 3D software was selected, the opportunities and developments were described. Model building, materials, models, model geometry, finite elements, boundary conditions and assumptions adopted in addressing problems described in detail. Three different tasks formulated and load-settlement dependence a comparison of the results with the experiment given. Conclusions are formulated according to the modeling results. Šiame straipsnyje aptarta spaustinių polių įrengimo technologija ir ją taikant vykstantys procesai, keičiantys pagrindo fizines ir mechanines charakteristikas. Spaustinio polio bandymui statine apkrova modeliuoti pasirinktas PLAXIS 3D programinis paketas ir aprašytos jo galimybės bei raida. Detaliai nupasakotas modelio kūrimas, medžiagų modeliai, modelio geometrija, baigtiniai elementai, kraštinės sąlygos ir priimamos prielaidos sprendžiant problemą. Suformuluoti trys sprendžiami uždaviniai ir apkrovos bei nuosėdžio priklausomybe pateikiamas rezultatų palyginimas su eksperimentu. Atsižvelgiant į modeliavimo rezultatus suformuluotos išvados.


2013 ◽  
Vol 790 ◽  
pp. 227-230
Author(s):  
Jian Feng Su ◽  
Yu Feng Xu

Floor slab static load test is a important method to judge the performance and carrying capacity of the slab. This paper, with the background of a factory frame-structure slab, introduced the testing scheme, the details of the testing process as well as the test results. The testing cases provide a useful reference for the same type of project.


2014 ◽  
Vol 22 (4) ◽  
pp. 1-10 ◽  
Author(s):  
Michal Hoľko ◽  
Jakub Stacho

Abstract The article deals with numerical analyses of a Continuous Flight Auger (CFA) pile. The analyses include a comparison of calculated and measured load-settlement curves as well as a comparison of the load distribution over a pile's length. The numerical analyses were executed using two types of software, i.e., Ansys and Plaxis, which are based on FEM calculations. Both types of software are different from each other in the way they create numerical models, model the interface between the pile and soil, and use constitutive material models. The analyses have been prepared in the form of a parametric study, where the method of modelling the interface and the material models of the soil are compared and analysed. Our analyses show that both types of software permit the modelling of pile foundations. The Plaxis software uses advanced material models as well as the modelling of the impact of groundwater or overconsolidation. The load-settlement curve calculated using Plaxis is equal to the results of a static load test with a more than 95 % degree of accuracy. In comparison, the load-settlement curve calculated using Ansys allows for the obtaining of only an approximate estimate, but the software allows for the common modelling of large structure systems together with a foundation system.


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