Flexural behavior of frozen soil

1986 ◽  
Vol 23 (3) ◽  
pp. 355-361 ◽  
Author(s):  
Sweanum Soo ◽  
Robert K. Wen ◽  
Orlando B. Andersland
Keyword(s):  
Creep Condition ◽  
Frozen Soil ◽  
Experimental Results ◽  
Flexural Behavior ◽  
Secondary Creep ◽  
Creep Properties ◽  
Steel Bar ◽  
Frozen Sand ◽  
Reinforced Earth ◽  
Deflection Rate

Plain and reinforced frozen sand beams were loaded incrementally in pure bending at −6 and −10 °C. For plain beams, the deflection rate (during secondary creep) showed a linear relationship with applied load on a log–log scale while experimental results of beams reinforced with a single 4.76 mm diameter steel bar showed a bilinear relationship. The observed deflection behavior was a result of the combined effects of soil creep in tension, compression, and adfreeze bond at the reinforcement/frozen soil interface.To analyze the flexural behavior of frozen soil, one-dimensional finite elements with different creep properties in tension and in compression were used in conjuction with the power creep law or the hyperbolic sine creep law. For the secondary creep condition and the power creep law, analytical solutions for frozen soil beam behavior are presented. Numerical results indicate reasonable agreement with experimental results. Key words: adfreeze bond, creep properties, flexural strength, frozen soils, reinforced earth.

Sharp cone testing of creep properties of frozen sand

1992 ◽  
Vol 29 (5) ◽  
pp. 757-764 ◽  
Author(s):  
B. Ladanyi ◽  
J. Sgaoula
Keyword(s):  
Field Testing ◽  
Frozen Soil ◽  
Theoretical Interpretation ◽  
Creep Properties ◽  
Frozen Sand ◽  
Cone Field ◽  
Sharp Cone ◽  
Constant Axial Load

The paper describes a new field testing method, called the sharp cone test, intended for in situ determination of creep properties of frozen soils and ice. The method consists of pushing a smooth, low-angle, cone into a predrilled conical portion of a borehole. The creep properties of the material are determined by applying a constant axial load on the cone, and by observing its time-dependent axial displacement as it penetrates and enlarges the conical hole. The paper describes the test, gives its theoretical interpretation, and shows the results of a series of tests carried out in a frozen sand. Key words : frozen soil, ice, sharp cone, field testing, creep properties.

scholarly journals Finite Element Analysis of Artificially Frozen C-Phi soil

2019 ◽  
Vol 8 (4) ◽  
pp. 12722-12728
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Frozen Soil ◽  
Experimental Results ◽  
Soil Freezing ◽  
Strength Parameter ◽  
Frozen Ground ◽  
Element Analysis ◽  
Test Setup ◽  
Geological Conditions

Artificial Ground Freezing techniques eliminate the need for structural supports during the course of an excavation, as frozen ground is solid and waterproof. At present, it is adopted as an effective way to deal with various construction ground control challenges such as the mitigation of seepage infiltration into tunnels and shaft excavations; or ground strengthening for excavation. In-depth knowledge of the frozen soil characteristics through experiments and the development of suitable constitutive models that suit the geological conditions of our country are necessary to predict the strength and behavior of the frozen soils. Numerical analysis of frozen soil can be used for mass works like tunneling which cannot be experimentally verified. This paper presents a validation of experimental results obtained from laboratory setup and soil freezing system for C-Phi soil. The main aim is to compare numerical and experimental results and hence obtaining the shear strength parameter of the soil, similar to the conventional triaxial test setup. To perform numerical analysis Finite element tool ANSYS 19 is used. Soil model is made in ANSYS 19 and required loads are inputted to performed the analysis similar to the experimental method. The result obtained from experimental test setup and numerical analysis was verified and compared and it was found that values of numerical results lies closer to experimental results

scholarly journals Freezing Technology: Challenges and Prospects for Sustainable Development in Urban Infrastructure

2019 ◽  
Vol 5 (2) ◽  
pp. 169
Author(s):  
Shunji Kanie
Keyword(s):  
Sustainable Development ◽  
Urban Infrastructure ◽  
Experimental Results ◽  
Practical Application ◽  
Environmental Friendliness ◽  
Use Of Space ◽  
Freezing Soil ◽  
The Arts ◽  
Ground Freezing ◽  
Frozen Sand

Ground freezing has been broadly applied to construction and maintenance works of infrastructures because of its environmental friendliness. Since freezing technology represented by ground freezing can improve the strength of soil as well as its water-tightness, it becomes an essential technology for construction and maintenance of urban infrastructures where the use of space in underground has already been highly integrated. In this paper, overview of the freezing technology is introduced with some important characteristics of freezing soil for practical application. In addition, freezing technology is used for interesting works which could not be completed without freezing, and the state of the arts in freezing technology is presented. A pipe-in-pipe, now the authors are developing, is an example to utilize the potential of frozen sand, and the effect of freezing is explained with experimental results.

scholarly journals Flexural Behavior of Fiber-Reinforced Self-Stressing Concrete T-Shaped Composite Beams

2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Boxin Wang ◽  
Ruichang Fang ◽  
Qing Wang
Keyword(s):  
Composite Beam ◽  
Mechanical Analysis ◽  
Composite Beams ◽  
Experimental Results ◽  
Flexural Behavior ◽  
Fiber Reinforced ◽  
Beam Test ◽  
Test Beam ◽  
Bending Performance ◽  
Laminated Layer

Given the excellent crack resistance performance of steel fiber-reinforced self-stressing concrete (SFRSSC), the bending performance of some composite beams with SFRSSC laminated layers was studied. The experiment conducted in this study comprised a single-span composite beam test (including 3 test beams) and a two-span continuous composite beam test (including 2 test beams). All the test beams were T-shaped. The cracking load, yielding load, and ultimate load of all the test beams were recorded and comparatively analyzed. Experimental results showed that the cracking load of the test beam with an SFRSSC laminated layer is significantly increased. Mechanical analysis and numerical simulation of the test beams were conducted, and the obtained results agreed well with the experimental results. The composite beams under different working conditions were also numerically simulated. Through the simulation, reasonable ranges of precompressive stress and length of the SFRSSC laminated layer at intermediate support of continuous composite beam were obtained.

scholarly journals Detection of Single Steel Strand Distribution in Grouting Duct Based on Capacitive Sensing Technique

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2564 ◽  
Author(s):  
Nan Li ◽  
Mingchen Cao ◽  
Hangben Du ◽  
Cunfu He ◽  
Bin Wu
Keyword(s):  
Capacitive Sensor ◽  
Experimental Results ◽  
Capacitive Sensing ◽  
Capacitance Measurements ◽  
Position Detection ◽  
Steel Bar ◽  
Sensor Structure ◽  
Steel Strand ◽  
Center Distance ◽  
Post Tensioned

Grouting ducts (containing steel strands) are widely used to increase the structural strengths of infrastructures. The determination of the steel strand’s integrity inside of ducts and the grouting quality are important for a strength evaluation of the structure. In this study, a capacitive sensing technique was applied to identify the cross-sectional distribution of the steel strands. The distribution was expressed in polar coordinates in an external post-tensioned pre-stressed duct model. An improved capacitive sensor structure was designed, which consisted of four electrodes, and different electrode-pairs were used to determine various locations’ information of the steel strands. Two rounds of measurements were conducted using the designed sensor to detect the angle (θ) and center distance (r) of the steel strand in the duct. The simulated and experimental results are presented and analyzed. In general, it is difficult to locate the angle of a steel strand directly from first-round capacitance measurements by analyzing the experimental results. Our method based on Q-factor analysis was presented for the position detection of a steel bar in an external post-tensioned pre-stressed duct. The center distance of the steel bar could be identified by second-round capacitance measurements. The processed results verified the effectiveness of the proposed capacitive sensor structure. Thus, the capacitive sensing technique exhibited potential for steel strand cross-section distribution detection in external post-tensioned pre-stressed ducts.

Investigation of tensile and flexural behavior of biaxial and rib 1 × 1 weft-knitted composite using experimental tests and multi-scale finite element modeling

2019 ◽  
Vol 53 (23) ◽  
pp. 3201-3215 ◽  
Author(s):  
Reza Hessami ◽  
Aliasghar Alamdar Yazdi ◽  
Abbas Mazidi
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Experimental Results ◽  
Flexural Behavior ◽  
Bending Tests ◽  
Three Point Bending ◽  
Element Modeling ◽  
Multi Scale ◽  
Scale Modeling ◽  
Composite Samples

In this study, tensile and flexural behavior of biaxial and rib weft-knitted composite is obtained numerically and experimentally. Multi-scale finite element modeling is employed to simulate the tensile and flexural behavior of composite samples. In the finite element modeling, the geometry of a unit cell of each fabric is initially modeled in ABAQUS software, and then periodic boundary conditions were applied to a unit cell. The stiffness matrix for each structure was obtained by a python code via meso scale modeling and used as input data for the macro modeling. To validate the numerical model, two types of weft-knitted fabrics (rib 1 × 1 and biaxial fabrics) are produced by a flat weft knitting machine. Epoxy resin is used to construct composite by the vacuum injection process (VIP). After that, the tensile and three-point bending tests were applied to composite samples. The experimental results showed that tensile strength and tensile modulus of biaxial composites are greater than rib composites, in both wale and course directions. Moreover, in three-point bending test, biaxial composite showed more strength and more stiffness in comparison to rib composite. Finite element results were compared to experimental results in tensile and bending tests. The results showed that good agreement with experimental results in the linear section of tensile and flexural behavior of composites. Consequently, the current multi-scale modeling can be used to predict the stiffness matrix and mechanical behavior of complex composite structures such as knitted composites.

scholarly journals Analysis of Three-Dimensional Damage Constitutive Model of Frozen Sand Based on the Influence of Intermediate Principal Stress and Temperature

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Shilong Ma ◽  
Zhaoming Yao ◽  
Shuang Liu ◽  
Xuan Pan
Keyword(s):  
Constitutive Model ◽  
Weibull Distribution ◽  
Principal Stress ◽  
Three Dimensional ◽  
Intermediate Principal Stress ◽  
Frozen Soil ◽  
Stress Coefficient ◽  
Frozen Sand ◽  
Distribution Parameters ◽  
Damage Constitutive Model

To study the mechanical properties of frozen soil, it is necessary to understand the damage characteristics of frozen soil. Four types of three-dimensional indoor tests of frozen sand were carried out at −5°C, −10°C, and −15°C to study the mechanical damage properties. These include different stress path tests with the principal stress coefficients of 0, 0.25, 0.5, and 0.75 while analyzing the entire failure process. First, the three-dimensional compression test of frozen sand was studied to analyze the influence of temperature and intermediate principal stress coefficient on the large principal stress of frozen soil. The damage cost of frozen sand under the influence of different temperatures and intermediate principal stress coefficients was also established. Second, using the characteristics of discreteness and randomness of the distribution of the microelements inside the frozen soil and assuming that the failure of the microelement of the frozen soil obeys the Weibull distribution, the Drucker–Prager strength criterion was used as the statistical distribution variable of the microelement of the frozen soil based on the strain equivalence hypothesis, statistical theory, and continuous damage mechanics. This allows for a constitutive model of frozen sand damage under the three-dimensional stress state to be established. Finally, the model parameter values through low-temperature three-dimensional test data were able to be determined. This model allows for the physical meaning of Weibull distribution parameters F0 and m to be analyzed, and the distribution parameters with temperature and intermediate principal stress coefficient can be modified to obtain a modified frozen sand damage constitutive model. The results show that the modified damage constitutive model can simulate the entire process curve of the large principal stress-strain of frozen sand. It shows that the large principal stress of frozen sand increases with the increase of temperature and intermediate principal stress coefficient. Concurrently, the frozen sand damage constitutive model proposed in this paper can describe the deformation behavior of frozen soil under different temperature and stress paths and can be adapted to various other sediment types.

Approach and Effect Analysis of Amplitude Frequency Performance Improvement in Metal Bar Cropping with Variable Frequency Vibration

2012 ◽  
Vol 152-154 ◽  
pp. 770-774
Author(s):  
Li Jun Zhang ◽  
Jie Qiong Xue ◽  
Sheng Dun Zhao ◽  
Yong Rui Zhao
Keyword(s):  
Performance Improvement ◽  
Cross Section ◽  
Narrow Range ◽  
Experimental Results ◽  
Variable Frequency ◽  
Structure Model ◽  
Effect Analysis ◽  
Steel Bar ◽  
Different Types ◽  
And Control

In order to solve the narrow range and control difficulties of the excited frequency in metal bar cropping with variable frequency vibration, the structure of the eccentric block in cropping machine was improved on in the paper and a new structure model of changing the integral eccentric block into one of main eccentric block and some small adjustable eccentric blocks, was also proposed. The key parameters of the cropping machine in the action of two different types of eccentric blocks were analyzed theoretically in detail. At the same time, the corresponding amplitude frequency characteristics of the cropping machine were also obtained. The cropping experimental results of 45 steel bar show that the cross-section quality and the cropping time are improved remarkably in the action of one main eccentric block and four adjustable eccentric blocks, comparing with the cropping results in the action of the whole eccentric block.

FLEXURAL BEHAVIOR OF HIGH STRENGTH GEO-POLYMER CONCRETE BEAMS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Vankudothu Bhikshma ◽  
Kandiraju Promodkumar ◽  
Putta Panduranghiah
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Research Work ◽  
High Strength ◽  
Experimental Results ◽  
Flexural Behavior ◽  
Polymer Concrete ◽  
Conventional Concrete ◽  
Granulated Blast Furnace Slag ◽  
Load Carrying

The demand for concrete is increasing day by day. As the consumption of cement is increased, environmental issues arise due to the release of CO2 during the manufacturing of cement. The objective of this research work is to produce a pollution free concrete with a combination of fly ash and GGBS (Ground granulated blast furnace slag) and without the use of cement. In this paper an attempt was made to study the mechanical properties of high strength geo-polymer concrete of grade M60 using GGBS, fly ash and micro silica. The testing program was planned for the mechanical properties of geo-polymer concrete and flexural behavior of corresponding beams. The experimental results indicated that the geo-polymer concrete M60 grade has a compressive strength of 70.45 MPa at the age of 28 days cured at ambient condition. Further, flexural strength and split tensile strengths for M60 grade high strength geo-polymer concrete at 28 days were observed to be 5.45 MPa and 3.63 MPa respectively. The modulus of elasticity was higher than the theoretical value proposed by IS 456-2000. It was also observed that the load carrying capacity of M60 grade high strength geo-polymer concrete found to be more than corresponding grade conventional concrete. The load-deflection, moment-curvature relationships were studied. The experimental results were encouraging to continue for further research in the area high strength geo-polymer concrete.

Behavior of Foam Particles Lightweight Concrete with Time

2018 ◽  
Vol 8 (04) ◽  
Author(s):  
Sohila A. El-Khouly ◽  
Amr H. Zaher ◽  
Ehab F. Sadek ◽  
Khalid M. Hilal
Keyword(s):  
Lightweight Concrete ◽  
Load Level ◽  
Experimental Results ◽  
Time Dependent ◽  
Flexural Behavior ◽  
Unit Weight ◽  
Experimental Program ◽  
Sustained Load ◽  
Polystyrene Foam ◽  
Loading Test

Lightweight Concrete with polystyrene foam particles (LWC) was obtained through the use of polystyrene foam as a partial aggregate’s replacement to reduce the concrete dry unit weight from 23 KN/m3 to 18.50 KN/m3. This research presents an experimental and theoretical investigation in the long-term behavior of LWC in compression and flexure. Two experimental programs were conducted; namely, creep and shrinkage of LWC under compressive loading test, and the time-dependent flexural behavior of reinforced LWC beams. The main variable in the first experimental program was the percentage of sustained load, while the main variables in the second experimental program were the percentage of sustained load and the percentage of compression reinforcement. Experimental results showed that LWC exhibits a significantly higher time-dependent strain (shrinkage plus creep) than normal weight concrete (NWC) under sustained compressive load and at the same compressive strength, with an increasing percentage about 9%. The creep strains of LWC seemed to be proportional to the stress to strength ratio. The timedependent deflections of the LWC beams were higher than those of NWC beams with increasing percentage about 25%. Addition of compression steel reinforcement (As`) to LWC beams reduced time-dependent deflections. Sustained load level and LWC time-dependent deflection were directly proportional. Finally, models and equations proposed by different codes were used to evaluate the obtained experimental results. From the theoretical study, it was found that Bazant-Baweja B3 Model gave superior shrinkage strains prediction for LWC. The ACI 209R-92 presented preferable predictions of creep strain and time-dependent deflection of LWC.

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