scholarly journals Method of Calculating the Vertical Displacement and Additional Stress of Existing Tunnels under the Influence of Grouting Rings of New Tunnels

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1623
Author(s):  
Yongjie Qi ◽  
Gang Wei ◽  
Yu Xie
Keyword(s):  
Calculation Method ◽  
Mechanical Model ◽  
Volume Expansion ◽  
Vertical Displacement ◽  
Additional Stress ◽  
Stochastic Medium ◽  
Medium Theory ◽  
Volumetric Expansion ◽  
Engineering Data ◽  
Good Agreement

In order to reduce the disturbance to adjacent tunnels caused by tunnel crossing, the existing tunnels are often reinforced by setting grouting rings along the pipe piece ring. In this context, the volume expansion of the grouted soil has to be taken into account, and a mechanical model of the volume expansion of the grouting rings is proposed here to study the effect of the grouting rings of new tunnels on the additional stress on the existing tunnels as well as their vertical displacement. The additional stresses on and the vertical displacement of the axis of the existing tunnels caused by the expansion of the grouting rings were deduced based on the stochastic medium theory. The influences of various volumetric expansion rates (Q) of the grouting rings, different lengths of the grouting rings, and different tunnel crossing angles on the settlement of and the additional stress on the existing tunnels were studied. The results demonstrate that the grouting rings can effectively reduce the impacts of the additional stress and the settlement deformation on the existing tunnels. The results of the tunnel settlement obtained from the calculation method proposed in this paper are in good agreement with the measured engineering data.

scholarly journals Method of Calculating the Compensation for Rectifying the Horizontal Displacement of Existing Tunnels by Grouting

2020 ◽  
Vol 11 (1) ◽  
pp. 40
Author(s):  
Yongjie Qi ◽  
Gang Wei ◽  
Feifan Feng ◽  
Jiaxuan Zhu
Keyword(s):  
Volume Expansion ◽  
Soil Layer ◽  
Horizontal Displacement ◽  
Soil Mass ◽  
Calculation Model ◽  
Additional Stress ◽  
Corrective Effect ◽  
Engineering Data ◽  
Subway Tunnels ◽  
Good Agreement

Sleeve valve pipe grouting, an effective method for reinforcing soil layers, is often employed to correct the deformation of subway tunnels. In order to study the effect of grouting on rectifying the displacement of existing tunnels, this paper proposes a mechanical model of the volume expansion of sleeve valve pipe grouting taking into consideration the volume expansion of the grouted soil mass. A formula for the additional stress on the soil layer caused by grouting was derived based on the principle of the mirror method. In addition, a formula for the horizontal displacement of a tunnel caused by grouting was developed through a calculation model of shearing dislocation and rigid body rotation. The results of the calculation method proposed herein were in good agreement with actual engineering data. In summary, enlarging the grouting volume within a reasonable range can effectively enhance the grouting corrective effect. Further, with an increase in the grouting distance, the influence of grouting gradually lessens. At a constant grouting length, setting the bottom of the grouting section at the same depth as the lower end of the tunnel can maximize the grouting corrective effect.

scholarly journals Ground Movement Analysis Based on Stochastic Medium Theory

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Meng Fei ◽  
Wu Li-chun ◽  
Zhang Jia-sheng ◽  
Deng Guo-dong ◽  
Ni Zhi-hui
Keyword(s):  
Distribution Function ◽  
Back Analysis ◽  
Movement Analysis ◽  
Measured Data ◽  
Ground Movement ◽  
Pile Driving ◽  
Normal Distribution Function ◽  
Stochastic Medium ◽  
Medium Theory ◽  
Vertical Ground

In order to calculate the ground movement induced by displacement piles driven into horizontal layered strata, an axisymmetric model was built and then the vertical and horizontal ground movement functions were deduced using stochastic medium theory. Results show that the vertical ground movement obeys normal distribution function, while the horizontal ground movement is an exponential function. Utilizing field measured data, parameters of these functions can be obtained by back analysis, and an example was employed to verify this model. Result shows that stochastic medium theory is suitable for calculating the ground movement in pile driving, and there is no need to consider the constitutive model of soil or contact between pile and soil. This method is applicable in practice.

Reversible Torsional Actuation of Hydrogel Filled Multifilament Fibre Actuator

Actuators ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 244
Author(s):  
Xi Zhang ◽  
Jinxuan Zhang ◽  
Bidita Salahuddin ◽  
Shuai Gao ◽  
Shazed Aziz ◽  
...  
Keyword(s):  
Volume Expansion ◽  
Real Life ◽  
Torsional Stiffness ◽  
Theoretical Treatment ◽  
Theoretical Estimation ◽  
Polymer Fibre ◽  
High Moisture ◽  
Smart System ◽  
Volumetric Expansion ◽  
Torsional Rotation

Twisted polymer fibre actuators provide high torsional rotation from stimulated volume expansion, induced either by chemical fuelling, thermal stimulation, or electrochemical charging. One key limitation of these actuators is the irreversibility of torsional stroke that limits their feasibility when considering real-life smart applications. Moreover, scaling the torsional stroke of these actuators becomes difficult when these are integrated into practically usable systems such as smart textiles, due to the external and variable opposing torque that is applied by the adjacent non-actuating fibres. Herein, a simple composite type torsional actuator made of hydrogel coated commercial textile cotton multifilament fibre is demonstrated. This novel actuator is of high moisture responsiveness, given that hydrogels are capable of providing huge volume expansion and twisting the overall system can transform the volumetric expansion to fibre untwisting based torsional actuation. Theoretical treatment of torsional actuation is also demonstrated based on the change in torsional stiffness of dry and wet fibres as well as a few externally applied torques. The agreement between experimental measurements and theoretical estimation is found reasonable, and the investigation allows the near-appropriate estimation of torsional stroke before integrating an actuator into a smart system.

scholarly journals Deformation prediction analysis of vertical displacement of deep foundation pit based on LIBSVM

2020 ◽  
Vol 206 ◽  
pp. 01021
Author(s):  
Yueyao Zhao ◽  
Jiawei Zhang ◽  
Haojie Li
Keyword(s):  
Support Vector Machine Model ◽  
Hot Spot ◽  
Vertical Displacement ◽  
Support Vector ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Machine Model ◽  
Deformation Prediction ◽  
Deep Foundation Pit ◽  
Good Agreement

The reliable prediction of the surface vertical displacement deformation of deep foundation pits is of great significance to the excavation of large foundation pits. The support vector machine model (LIBSVM) has become a hot spot in the prediction of deep foundation pit deformation and provides a new prediction for the deformation of deep foundation pits. In this paper, taking the deep foundation pit of Daoxianghu Road Station in xx as an example, a prediction model of vertical displacement on the ground is established based on LIBSVM and analysis shows that the prediction results based on the model are in good agreement with the measured data, and the MSE reaches 0.0323. The model is effective and has an effective prospective skill.

Micro-Mechanical Model for Thermo-Oxidative Aging of Elastomers

2018 ◽  
Author(s):  
Hamid Mohammadi ◽  
Roozbeh Dargazany
Keyword(s):  
Mechanical Model ◽  
Strain Energy ◽  
Aging Process ◽  
Polymer Chains ◽  
Constitutive Behavior ◽  
Network Decomposition ◽  
Oxidative Aging ◽  
The One ◽  
Micro Sphere ◽  
Good Agreement

In this study, a micro-mechanical model for constitutive behavior of elastomers subjected to thermo-oxidative aging is proposed. The model is based on the network decomposition concept and lies within the framework of continuum mechanics. It is assumed that the aging process leads to the formation of a new network with tighter chains. Accordingly, the strain energy of the system is constituted of two independent sources, the energy of the original soft network and the one of the reformed network. These strain energies were computed by integration of entropic energy of polymer chains in each direction of a micro-sphere. The model demonstrates good agreement with different experimental data on relaxation and intermittent tests.

scholarly journals A New Modified Peck Formula for Predicting the Surface Settlement Based on Stochastic Medium Theory

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Zhanping Song ◽  
Xiaoxu Tian ◽  
Yuwei Zhang
Keyword(s):  
Friction Angle ◽  
Surface Settlement ◽  
Calculation Error ◽  
Stochastic Medium ◽  
Medium Theory ◽  
Comparison Results ◽  
Calculation Process ◽  
The Difference ◽  
Shallow Buried Tunnel ◽  
Prediction Approach

Peck method and stochastic medium method are the two most commonly used methods to estimate surface settlement caused by tunnel excavation. However, the Peck method was not suitable for a shallow-buried tunnel, and the calculation process of the stochastic medium theory was complicated. To solve this problem, in this paper, a simple and accurate prediction approach for surface settlement was obtained by improving the Peck method based on the basic idea of stochastic medium theory. In detail, the over-excavation area of the tunnel was divided into n independent units, and the surface settlement caused by the collapse of each unit was calculated, respectively. Then, the total surface settlement can be obtained by superimposing surface settlement induced by each unit. Taking the shallow-buried section of Mulingguan tunnel entrance as a case, the surface settlement calculated by the modified Peck formula and original Peck formula was compared with the observed data, respectively. The comparison results indicated that the surface settlement calculated by the modified Peck formula is closer to the observed data than that calculated by the original Peck formula in the calculation process of surface settlement of shallow-buried tunnel. The table of recommendation for the number of units can be obtained by a discussion of reasonable n values. Finally, the difference between the original Peck formula and the modified Peck formula was analysed, and the results showed that the change rule of the surface settlement is consistent under the tunnel depth, internal friction angle, and ground loss of the tunnel. However, the calculation error of the surface settlements calculated by the original Peck formula is more significant than that calculated by modified Peck formula under the tunnel diameter ratio being less than 1.75. The modified Peck formula is more suitable for calculating the surface settlement under internal angle friction being less than 20° or greater than 40°. The research results expand the scope of application of the original Peck formula and enrich the calculation approach of surface settlement induced by underground excavation in tunnel construction.

Additional Stress Distribution in DJM Pile Composite Foundation and Simplified Calculation Method

2012 ◽  
Vol 594-597 ◽  
pp. 274-279
Author(s):  
Fang Ding He ◽  
Guang Jun Guo ◽  
Jian Qing Wu
Keyword(s):  
Stress Distribution ◽  
Calculation Method ◽  
Influential Factors ◽  
Composite Foundation ◽  
Good Effect ◽  
Additional Stress ◽  
Soft Foundation ◽  
Simplified Calculation ◽  
Simplified Calculation Method

Although DJM-Pile have a good effect on strengthening soft foundation,theories about additional stress are too complex or too simply to be used in project well.By adopting FEM software with considering of friction between soil and pile,simulate the additional stress in composite foundation because of DJM pile construction and compare with results gotten in Bossinesq method.The comparison shows that the distribution of additional stress is very similar.So considering several major influential factors,the paper updates the Bossinesq method and brings forward a simplified calculation method.

Improved hydration resistance of magnesia by EDTA and ammonium phosphate as additives

2017 ◽  
Vol 24 (1) ◽  
pp. 29-33
Author(s):  
Wenzheng Zhang ◽  
Bin Chen ◽  
Jiangnan Mou ◽  
Danyang Wang
Keyword(s):  
Ionic Conductivity ◽  
Ethylene Diamine Tetraacetic Acid ◽  
Volume Expansion ◽  
Particle Distribution ◽  
Ammonium Phosphate ◽  
Ethylene Diamine ◽  
Tetraacetic Acid ◽  
Volumetric Expansion ◽  
Key Factor ◽  
Hydration Resistance

AbstractThe control of magnesia (MgO) hydration ratio is a key factor in refractory slurry processing. The volumetric expansion that follows this reaction can result in MgO product cracks as MgO greatly tends to react with water. Thus, the antihydration of MgO is a key concern in refractory suspension processing. The performances of ammonium phosphate (AP) and ethylene diamine tetraacetic acid (EDTA) as antihydration additives were evaluated by using hydration tests, and ionic conductivity, pH, and particle distribution of MgO powders in water and ethanol were used to provide information related to the MgO powder in different liquids. The results showed that the antihydration additives AP and EDTA can inhibit MgO hydration to some extent; however, AP was more effective in preventing volume expansion.

Establishment and Validation of a 1-D Numerical Model of Unsteady Flow and Sediment Transport in the Three Gorges Reservoir (TGR)

2013 ◽  
Vol 444-445 ◽  
pp. 901-905
Author(s):  
Ren Yong Huang ◽  
Jie Zhang
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Unsteady Flow ◽  
Calculation Method ◽  
Three Gorges Reservoir ◽  
Three Gorges ◽  
The Three Gorges ◽  
Flow And Sediment Transport ◽  
Simulation Results ◽  
Good Agreement

A numerical model for simulating unsteady flow and sediment transport in the mainstream and its tributaries at the TGR was presented in this paper, and a three-gradation method was applied to solve the flow governing equation. A experience formula was gave for the calculation of the size of groups of different coefficient of saturation recovery based on the analysis, so the traditional calculation method was improved in this paper. The validity of the model was checked with the observed data of the TGR from 2003 to 2011. Good agreement between the calculation and observed data was obtained. The simulation results show that this model could be used to simulate the flow and sediment transport at the TGR.

scholarly journals Development of Characterization Techniques of Thermodynamic and Physical Properties Applied to the CO2-DMSO Mixture

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Brice Calvignac ◽  
Elisabeth Rodier ◽  
Jean-Jacques Letourneau ◽  
Jacques Fages
Keyword(s):  
Process Design ◽  
Published Data ◽  
Viscosity Data ◽  
Pressure Measurements ◽  
Co2 Solubility ◽  
Volumetric Expansion ◽  
Characterization Techniques ◽  
Dmso System ◽  
Good Agreement

This work is focused on the development of new characterization techniques of physical and thermodynamic properties. These techniques have been validated using the binary system DMSO-CO2 for which several studies of characterization have been well documented. We focused on the DMSO-rich phase and we carried out measurements of volumetric expansion, density, viscosity and CO2 solubility at 298.15, 308.15 and 313.15 K and pressures up to 9 MPa. The experimental procedures were compared and validated with the available literature data on SC-CO2-DMSO system. We made density and CO2 solubility measurements, using respectively the vibrating tube technology and two static analytical methods. Lastly, we developed an innovative falling body viscosimeter for high pressure measurements. All the measurements made are in good agreement with the already published data in spite of very different experimental techniques. This work is a contribution to the understanding of the DMSO-CO2 binary as it implements new viscosity data. Moreover, it opens new perspectives about the determination of the properties of other systems such as polymers-CO2 and fats-CO2, which are essential for supercritical process design such as extraction, crystallization, chromatography and synthesis reaction.

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