scholarly journals Calculation of Negative Frictional Resistance of Foundation Pile in Deep Fill Foundation

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ningyu Zhao ◽  
Hongjun Wu ◽  
Yi Song ◽  
Shun Xiang
Keyword(s):  
Axial Force ◽  
Pile Foundation ◽  
Frictional Resistance ◽  
Energy Balance Equation ◽  
Calculation Model ◽  
Measured Data ◽  
Hyperbolic Model ◽  
Distribution Law ◽  
Soil System ◽  
Foundation Pile

In deep fill foundations, the pile foundation might suffer from negative frictional resistance (NFR) due to the consolidation and settlement of the soil. The NFR will cause the pile to settle excessively and reduce its bearing capacity. However, there are not yet many accurate methods to calculate the NFR of foundation piles in deep fill foundations. To make up for the gap, this paper carries out shear tests on the pile-soil interface and discusses the mechanism of pile-side frictional resistance. Considering the distribution law of pile-side frictional resistance with depth, the authors proposed a piecewise calculation model for pile-side frictional resistance, which couples the hyperbolic model and effective stress method. Then, the energy balance equation of the pile when the NFR occurs was established in the light of the energy transfer of the pile-soil system during the settlement of the soil around the pile. Furthermore, the calculation formulas of the axial force and displacement of the pile at different depths were derived, considering the pile-soil displacement and the potential energy change of the pile-soil system. The proposed method was applied to calculate the NFR of the foundation pile in a construction site, and the calculated results were compared with the measured data. The results show that the axial force-depth curve of the pile obtained through theoretical calculation agrees well with the measured data. Hence, our method can accurately reveal the mechanical features of the pile foundation in deep fill foundations.

Study on Critical Anchorage Length of Bolts by Numerical Simulation Method

2012 ◽  
Vol 204-208 ◽  
pp. 4771-4775
Author(s):  
Bo Wang ◽  
Jian Nan Zhou ◽  
Feng Nian Jin ◽  
Mei Rong Jiang
Keyword(s):  
Numerical Simulation ◽  
Comparative Analysis ◽  
Frictional Resistance ◽  
Simulation Method ◽  
Calculation Model ◽  
Measured Data ◽  
Anchorage Length ◽  
Numerical Simulation Method

Numerical simulation method was used to study the problems on critical anchorage length of bolts. 3-D calculation model was built by FLAC program. By numerical simulation calculations, the conclusion could be drawn: the frictional resistance contribution had nothing to do with drawing forces, and was relevant to the bond stiffness of anchor mortar. And comparative analysis results of one engineering example showed that the calculated values by the presented method agreed well with the measured data.

Study on the Effective Slab Width of Composite Cable-Stayed Bridge under Axial Force

2012 ◽  
Vol 568 ◽  
pp. 200-203
Author(s):  
Xiang Nan Wu ◽  
Xiao Liang Zhai ◽  
Ming Min Zhou
Keyword(s):  
Axial Force ◽  
Shear Lag ◽  
Distribution Law ◽  
Slab Width ◽  
Cable Stayed Bridge ◽  
Stay Cables ◽  
Transmission Angle ◽  
Effective Flange Width ◽  
Width Coefficient ◽  
Cable Stayed Bridges

There exist evident shear-lag phenomena in large-span composite cable-stayed bridges under the action of axial force, especially in the deck with double main girders. In order to discuss the distribution law of the effective flange width coefficient along the span, caused by axial force, finite element computations of five composite cable-stayed bridges and theoretical analysis have been performed. The transmission angle of axial force caused by the axial compression of stay cables was given, meanwhile the formulas for computation effective slab width coefficient under axial force were suggested.

scholarly journals PENGARUH DIAMETER TIANG TERHADAP TAHANAN GESEK TIANG DALAM TANAH LEMPUNG

2019 ◽  
Vol 1 (3) ◽  
pp. 219-224
Author(s):  
Andikanoza Pradiptiya ◽  
A’isyah Salimah
Keyword(s):  
Pile Foundation ◽  
Structural Damage ◽  
Tensile Load ◽  
Frictional Resistance ◽  
Test Method ◽  
Scale Model ◽  
Friction Resistance ◽  
Average Value ◽  
Constant Rate ◽  
Pile Model

AbstractSome buildings impose limits on the foundation displacement that occur with relatively small values so as not to cause structural damage. The test method used was to make a model test box as a testing medium by simulating the actual model into the form of a scale model. The study was conducted using a single pile foundation with reduced scale, made of concrete with a diameter of 0.02 m, 0.03 m, 0.04 m and the length of each pile was 0.4 m. The pile model was mounted by pressing into the clay that had been compacted in the test box and then given a tensile load which refers to ASTM D3689-07 procedure E (Constant Rate of Uplift Test). Mobilization of pile friction resistance at critical displacement determined the frictional resistance of the ultimate pile units. The test results showed that the greater the diameter of the pile, the frictional resistance of the ultimate pile units would increase. The increase in frictional resistance of the ultimate pile units showed an average value of around 17.1%.Keywords : Pile foundation, Pile diameter, Friction resistance.AbstrakMeningkatnya pembangunan hunian mengakibatkan naiknya permintaan akan batako, hal ini tentunya Beberapa konstruksi bangunan memberikan batasan kepada perpindahan tiang yang terjadi dengan nilai yang relatif kecil supaya tidak menyebabkan kerusakan struktur. Metode uji yang dipakai adalah membuat box uji model sebagai media pengujian, dengan mensimulasikan model yang sebenarnya ke dalam bentuk model skala. Penelitian dilakukan menggunakan model pondasi tiang tunggal penampang lingkaran lingkaran skala tereduksi yang terbuat dari beton dengan diameter 0,02 m, 0,03 m, 0,04 m dan panjang  masing-masing tiang adalah 0,4 m. Model tiang dipasang dengan cara ditekan pada tanah lempung yang sudah dipadatkan dalam box uji kemudian diberikan beban tarik yang mengacu pada ASTM D3689-07 prosedur E (Constant Rate of Uplift Test). Mobilisasi tahanan gesek tiang pada perpindahan tiang kritis menetukan tahanan gesek satuan ultimit. Hasil uji memperlihatkan bahwa semakin besar diameter tiang, tahanan gesek satuan ultimit tiang akan bertambah. Peningkatan tahanan gesek satuan ultimit tiang menunjukkan rata-rata sekitar 17,1 %.Kata kunci : Pondasi Tiang, Diameter Tiang, Tahanan Gesek Tiang.

Numerical Simulation of Bored Pile-Soil Interface Shear Performance

2013 ◽  
Vol 438-439 ◽  
pp. 1427-1432
Author(s):  
Qian Xu Liao ◽  
Jin Cao ◽  
Jun Wei Tang
Keyword(s):  
Numerical Simulation ◽  
Clayey Soil ◽  
Frictional Resistance ◽  
Measured Data ◽  
Interface Shear ◽  
Bored Pile ◽  
Model Pile ◽  
Shear Performance ◽  
Bored Piles ◽  
Soil Interface

This paper derives a numerical simulation of direct shearing test and model pile test based on the measured data of bored piles. Characteristics of the interface between bored pile and soil around it are analyzed. Laws of the magnitude and the distribution range of point resistance and frictional resistance of the bored piles in granular and clayey soil are obtained and the mechanism on them is explained.

Research of Calculation Models for Exhaust Enthalpy of Steam Turbine

2012 ◽  
Vol 550-553 ◽  
pp. 3160-3163
Author(s):  
Yong Guang Ma ◽  
Ning Ran ◽  
Bing Zheng
Keyword(s):  
Energy Balance ◽  
Steam Turbine ◽  
Open System ◽  
Performance Monitoring ◽  
Thermal Power ◽  
Energy Balance Equation ◽  
Calculation Model ◽  
Power Generating Unit ◽  
Calculation Results ◽  
Unit Performance

For the low pressure (LP) cylinder of a steam turbine, computation of the exhaust enthalpy is an important part in thermal power generating unit performance monitoring. A new online model for calculating the exhaust enthalpy was proposed aiming at the limitation of existing online calculation model for calculating the enthalpy of steam turbine LP cylinder exhaust steam. This model treats LP cylinder, condenser and corresponding heater as an open system, according to the energy balance equation of this open system, figuring out its exhaust enthalpy. Calculation results of typical steam turbine show that: in a large load change range, the results are close to thermal experimental value, the accuracy is similar to energy balance method.

Interaction Analysis of Foundation Pit Excavation and Adjacent Existing Building's Pile Foundation

2014 ◽  
Vol 501-504 ◽  
pp. 286-290
Author(s):  
Shan Shan Xu ◽  
Qiu Sheng Gao
Keyword(s):  
Finite Element ◽  
Pile Foundation ◽  
Interaction Analysis ◽  
Vertical Displacement ◽  
Measured Data ◽  
Construction Site ◽  
Existing Buildings ◽  
Foundation Pit ◽  
Finite Element Software ◽  
Site Monitoring

Construction site-monitoring on adjacent existing building’s pile foundation,using ANSYS finite element software to simulate the deformation of adjacent pile foundation when foundation pit excavation. Combined with measured data to analyze the interaction of foundation pit excavation and adjacent existing building’s pile foundation and draw the conclusion that the measured settleme-nt of pit’s adjacent pile is greater than the model’s theoretical value and the pit excavation has certain influence on the pile foun-dation’s vertical displacement of existing buildings.

Research on CWR Design on Steel-Concrete Composite Beam Bridge in Alpine Region

2014 ◽  
Vol 587-589 ◽  
pp. 1708-1712
Author(s):  
Wei Long Sun ◽  
Feng Han
Keyword(s):  
Temperature Stress ◽  
Composite Beam ◽  
Calculation Model ◽  
Alpine Region ◽  
Bridge Pier ◽  
Distribution Law ◽  
Key Techniques ◽  
Beam Bridge ◽  
Broken Gap

In this paper, take one steel-concrete composite beam bridge in alpine region as the research object, by using the calculation model of “line-bridge-pier”integration, research the distribution law of rail additional contractility, deflection force and values of broken gap when rail is breaking. Propose the key techniques of laying temperature stress CWR on composite beam bridge, which will have great significance in guiding the design of similar projects.

Analysis on Pre-Stressed Friction Loss in Bending Channel under Contact Pressure Non-Uniform Distribution Hypothesis

2011 ◽  
Vol 255-260 ◽  
pp. 49-53 ◽  
Author(s):  
Hai Qian Cheng ◽  
Qing Hua Cheng ◽  
Kai Yin Zhang
Keyword(s):  
Uniform Distribution ◽  
Contact Pressure ◽  
Frictional Resistance ◽  
Friction Loss ◽  
Positive Pressure ◽  
Distribution Law ◽  
Contact Conditions ◽  
Friction Resistance ◽  
Loss Formula ◽  
Distribution Assumption

The pre-stressed friction loss formula in bending channel recommended by Bridge Rules was based on the uniform distribution hypothesis of contact pressure. From some conflicts in application of the formula, the non-uniform distribution law of the contact pressure was revealed. On the basis of elastic contact analysis, two types of non-uniform distribution hypothesis were proposed, including cosine and second-degree parabola distribution. Then the contact positive pressure expressions were derived respectively and the frictional resistance was calculated to compare with the calculated value under the uniform distribution. The results indicate that the friction resistance under any non-uniform distribution of positive pressure is less than under the uniform distribution. So the uniform distribution assumption of contact pressure does not cause Bridge Specifications formula underestimate friction loss. It is necessary to do further research on the applicability of Coulomb’s law under the contact conditions in the curved channel.

Ground Settlement Prediction Model and its Application for Tunneling Engineering above Mined-Out Regions

2012 ◽  
Vol 524-527 ◽  
pp. 592-597
Author(s):  
Shu Ren Wang ◽  
Hai Qing Zhang
Keyword(s):  
Field Data ◽  
Prediction Method ◽  
High Accuracy ◽  
Measured Data ◽  
Grey Model ◽  
Hyperbolic Model ◽  
Ground Settlement ◽  
Settlement Prediction ◽  
Tunneling Engineering ◽  
Huge Challenge

Although many types of curve fitting methods were used in ground settlement prediction, it is due to every prediction method was not perfect, they have some defects and shortcomings to some extent and ground settlement prediction be up against huge challenge. Usher model, being used for economic and resources prediction, is introduced to ground settlement prediction as a new method, and its mathematics features are also analyzed. After comparative analysis, Origin software is selected for parameters solution of Usher model with an explanation of the solving process. Based on the Shipogou tunnel project which through the mined-out regions in Qingdao-Yinchuan highway, the Usher model for ground settlement is established combining to the field data, of which the parameters are solved with the user-defined function and nonlinear tool of Origin. The predicting results being compared with that of grey model and hyperbolic model, it shows that Usher model is of good adaptability, high accuracy, simple and coinciding well with measured data.

scholarly journals Calculation of Bearing Capacity and Deformation of Composite Pile Foundation with Long and Short Piles in Loess Areas

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Tianzhong Ma ◽  
Yanpeng Zhu ◽  
Xiaohui Yang
Keyword(s):  
Theoretical Calculation ◽  
Bearing Capacity ◽  
Pile Foundation ◽  
Frictional Resistance ◽  
Operating Conditions ◽  
Neutral Point ◽  
Pile Foundations ◽  
Single Pile ◽  
Deformation Control ◽  
Composite Pile

In order to calculate the bearing capacity and settlement deformation of composite pile foundations with long and short piles in collapsible loess areas, the theoretical approximate solution was used to obtain the location of the neutral point of single piles. Additionally, based on the equation to calculate the bearing capacity of multielement composite foundations, a method considering the negative frictional resistance was proposed for calculating the bearing capacity of composite pile foundations with long and short piles. Based on the shear displacement method and the principle of deformation control, an equation to calculate the displacement and deformation of a composite pile foundation was presented. A model test with different operating conditions, i.e., a single pile, four piles, and eight piles, was designed to verify the proposed calculation methods. The results show that the location of the neutral point has a significant influence on the single-pile negative frictional resistance, and the neutral point ratio of the calculation meets the value range of the practical project. When the load at the top of the pile is relatively small, the experimental curve is consistent with the theoretical calculation curve, whereas when the load is comparatively large, the theoretically calculated displacement increase at the top of the pile is greater than the measured one. Under the premise that the theoretical calculation is in good agreement with the results, the theoretical value is larger than the actual value. And it contributes to strengthening engineering safety.

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