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 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 CONCERNING THE EXTRACTION OF A SLACK SOIL LAYER FROM COMPRESSIBLE THICKNESS OF FOUNDATION STRATUM OF FINITE WIDTH FOUNDATIONS

2019 ◽  
Vol 7 (4) ◽  
pp. 49-56
Author(s):  
Zaven Ter-Martirosyan ◽  
Armen Ter-martirosyan ◽  
Valery DEMYANENKO
Keyword(s):  
Analytical Solutions ◽  
Soft Soil ◽  
Soil Layer ◽  
Horizontal Displacement ◽  
Creep Model ◽  
Shear Stresses ◽  
Finite Width ◽  
Relative Depth ◽  
Weak Layer ◽  
Horizontal Displacements

The paper provides a quantitative assessment of the deflected mode of foundation stratum of finite width foundation, in the compressible thickness of which there is a slack clay soil layer. A number of criteria for assessing the possibility or impossibility of extruding a slack layer depending on its strength and rheological properties, as well as the relative thickness of the layer to its length (h/l) and the relative depth of the layer (h/d) have been given. Closed analytical solutions are given to determine the rate of Foundation precipitation depending on the rate of extrusion of the weak layer, including taking into account the damped and undamped creep. The analytical solutions in the article are supported by the graphical part made with the help of the Mathcad program. Plots of changes in shear stresses in the layer along the x axis at different distances from the axis and at different values 0, contours of horizontal displacement velocities in the weak layer at different distances from the x axis, plots of horizontal displacement velocities in the middle of the weak layer and plots of horizontal displacement velocities in the weak layer at different distances from the x axis are given. As a calculation model for describing the creep of a slack layer, rheological ones of the soil using power and hyperbolic functions and their modifications have been considered. In addition, most modern rheological models that take into account soil hardening during creep have been considered. Based on these models, the problem is solved by means analytical and numerical methods using the Mathcad PC and the PLAXIS PC according to the Soft Soil Creep model. The graphical part shows the isofields of horizontal displacements for 300 days and 600 days and the corresponding contours of horizontal displacements.

scholarly journals Profile degradations of podzolic chernozem of the territory of Male Polissia

2017 ◽  
pp. 98-110
Author(s):  
Volodymyr Haskevych
Keyword(s):  
Physical Properties ◽  
Soil Layer ◽  
Vegetation Period ◽  
Soil Mass ◽  
Water Erosion ◽  
Soil Protection ◽  
Erosion Processes ◽  
Average Annual Loss ◽  
Study Results ◽  
Statistical Field

The article presents the results of the study of Male Polissia podzolic chernozems profile degradation. The causes and consequences of this dangerous natural and man-made phenomenon resulting in changes in the habitus of soils, losses of soil mass and humus, deterioration of general physical properties and structural and aggregate composition, decrease in soil fertility and agriculture unprofitability on the slopes have been analysed. In the study of the profile degradation of podzolic chernozems, the following methods have been used: comparative-geographical, comparative-profile, soil-catena, analytical, and statistical. Field studies were conducted after the vegetation period. According to the study results, the thickness of the profile of weakly eroded podzolic chernozems, in comparison with non-eroded types, decreased by 17.0–35.5% as compared to the standard, which corresponds to satisfactory and pre-crisis condition, in medium eroded soils - by 32.2–63.4%, the degree of degradation is estimated as pre-crisis, crisis and catastrophic. In the highly eroded types, the thickness of the soil layer decreased by 47.8–74.9%, which indicates a high and very high (crisis) level of profile degradation. Erosion soil loss compared to the standard in weakly eroded podzolic chernozems is 1245.0-3744.6 t/ha, in medium eroded soil – 6762.4-8321.0 t/ha, and in highly-eroded soil – 8874.0-11595.0 t/ha. It has been established that chernozems as a result of water erosion from one hectare of weakly eroded podzolic, on average 39.47–118.70 tons of humus was eroded, 214.36-237.98 tons was eroded from medium eroded ones, and 240.49-267.84 tons from highly eroded soils. The average annual loss of humus is from 0.23-0.68 t/ha in weakly eroded types to 1.37-1.53 t/ha in highly eroded podzolic chernozems. Erosion processes result in deterioration of physical properties of soils. The use of dense and low-humus plumage horizons for plowing causes compaction of soils and deterioration of structure. Minimization of podzolic chernozem profile degradation in Male Polissia is possible provided that the system of anti-erosion measures, especially the conservation of highly eroded soils, the introduction of soil protection methods for soil cultivation, optimization of the structure of crop areas, ban on cultivated crops on slopes more than 3° steep, consolidation of small areas in larger arrays are applied. It is also necessary to introduce a system of basic and crisis monitoring over the condition of eroded soils. Key words: Male Polissia, podzolic chernozems, profile degradation, water erosion, humus, soil conservation.

scholarly journals Seismic Response of Prestressed Anchors with Frame Structure

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Shuaihua Ye ◽  
Zhuangfu Zhao
Keyword(s):  
Seismic Response ◽  
Shaking Table Test ◽  
Coupling Effect ◽  
Soil Mass ◽  
Calculation Model ◽  
Shaking Table ◽  
Frame Structure ◽  
Dynamic Calculation ◽  
Concentrated Mass ◽  
Linear Spring

Based on the equivalent mass-spring model and considering the coupling effect between creep soil and prestressed anchors, the dynamic calculation model of prestressed anchors with frame structure is established. The soil mass is expressed in the form of concentrated mass. The action of the frame structure on the soil is treated as a parallel coupling of a linear spring and a linear damper, and the free section of the anchor is treated as a linear spring. Considering the creep characteristics, the soil is regarded as a Generalized Kelvin body and the anchoring section of the anchor is regarded as an equivalent spring body, which are coupled in parallel. Considering the effect of slope height, the dynamic calculation model is solved and the seismic response is analyzed. Finally, an engineering example is used to verify the calculation method in this paper, and the results are compared with the shaking table test and numerical simulation. It shows that the calculation model proposed in this paper is safe and reasonable for the seismic design and analysis of the slope supported by prestressed anchors with frame structure.

Friction Structure Effect Analysis of Granular Materials in Foundation Soil

2012 ◽  
Vol 591-593 ◽  
pp. 1083-1088
Author(s):  
Chang Dan Wang ◽  
Shun Hua Zhou ◽  
Hui Su
Keyword(s):  
Stress Distribution ◽  
Granular Materials ◽  
Soil Layer ◽  
Stress Transfer ◽  
Fine Sand ◽  
Structure Effect ◽  
Additional Stress ◽  
Foundation Soil ◽  
Effect Analysis ◽  
Boussinesq Solution

To research and analyze the additional stress distribution and change of granular materials, the model tests are used to observe vertical additional stress in different position and depth. And the comparison between observed values and theoretical values is conducted to analyze the transmission and attenuation of additional stress in granular materials. The research results show that calculated values are based on Boussinesq solution which ignores the property of soil layer (materials), the distribution of additional stress for fine sand which belongs to granular materials is largely deviated from theoretical value. For granular materials, inner friction structure effect is evident influence to additional stress transfer. And continue using calculation method which is based on continuum materials will have bigger difference and even wrong.

Calculation Model of Mass Action Concentrations for CaO-MnO-FeO-SiO2-MgO-Al2O3 Slags Based on the Ion and Molecule Coexistence Theory

2012 ◽  
Vol 476-478 ◽  
pp. 134-138
Author(s):  
Xiao Hong Yang ◽  
Xiao Chun Ma ◽  
Cheng Chuan Wu ◽  
Guo Guang Cheng
Keyword(s):  
Phase Diagrams ◽  
Thermodynamic Model ◽  
Slag System ◽  
Calculation Model ◽  
Mass Action ◽  
Structural Units ◽  
Coexistence Theory ◽  
Slag Structure ◽  
Calculation Results ◽  
Good Agreement

According to the ion and molecule coexistence theory (IMCT) of slag structure and corresponding phase diagrams, a thermodynamic model for calculating mass action concentrations of structural units or ion couples of CaO-MnO-FeO-SiO2-MgO-Al2O3 slags was established. Equilibrium mass action concentrations of each structure unit were gained. And the calculation results of NFeO and NMnO were compared with measured aFeO and aMnO. The comparison shows that the calculated values of NFeO and NMnO are in good agreement with the reported measured values of aFeO and aMnO, so this calculating model could fairly describe the characteristics of the slag system.

scholarly journals Numerical Method for Fuel Distribution Downstream of the Emulsifying Channel Injector

1985 ◽  
Author(s):  
Liu Bing ◽  
Wang Hong-Ji
Keyword(s):  
Differential Equation ◽  
Numerical Method ◽  
Calculation Model ◽  
Experimental Results ◽  
Two Dimensional ◽  
Physical Processes ◽  
Mixture Formation ◽  
Fuel Distribution ◽  
Good Agreement

Based upon experimental results, the physical processes of fuel-air mixture formation downstream of the emulsifying channel injector (ECI) have been studied and a calculation model for predicting fuel distribution downstream of ECI has been proposed in this paper. The two-dimensional differential equation of diffusion is solved by numerical method and the fuel distribution downstream of ECI is calculated. The calculated values are in good agreement with the experimental results.

scholarly journals Prediction of machining deformation and reasonable design of gear blank for split straight bevel gear

2021 ◽  
Author(s):  
Bin Wang ◽  
Chenxiao Yan ◽  
Peiyao Feng ◽  
Shuaipu Wang ◽  
Shuo Chen ◽  
...  
Keyword(s):  
Calculation Model ◽  
Bevel Gear ◽  
Geometric Parameters ◽  
Machining Process ◽  
Additional Stress ◽  
Element Analysis ◽  
Bending Deformation ◽  
Straight Bevel Gear ◽  
Machining Deformation ◽  
The Moment

Abstract The deformation of gear blank is serious in the machining process of the split straight bevel gear,considering the material and the design of gear blank, the relationship between the change of additional stress and bending deformation of gear blank is studied, and the calculation model of the internal additional stress and additional torque during the gear cutting is established.According to the moment-area method, the calculation formula of the bending deformation of gear blank is derived, and combined with the time-varying stiffness, the mathematical model of the gear blank deformation is obtained. The theoretical calculation, finite element analysis and experimental results are highly consistent.Based on the above research, the internal relationships between the machining deformation and the geometric parameters such as the thickness, diameter and gear module of the split gear blank is analyzed, and the reasonable design of the geometric parameters of the split gear blank and the reasonable dividing law of the gear blank are explored.

scholarly journals A Theoretical Calculation Method of the Unsupported Span for the Shallow Tunnel in the Soft Stratum

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xiaoxu Tian ◽  
Zhanping Song ◽  
Guannan Zhou ◽  
Xiaowei Zhang
Keyword(s):  
Soft Rock ◽  
Friction Angle ◽  
Soil Mass ◽  
Calculation Model ◽  
Support Pressure ◽  
Shallow Tunnel ◽  
Tunnel Face ◽  
Rock Stratum ◽  
The Stability ◽  
Shallow Buried Tunnel

During the construction of the tunnel in soft stratum, it is often found that the unsupported span is too large, resulting in instability of the tunnel face and collapse of the vault. However, the unsupported span was often selected according to the experience of engineers in the actual construction process, which was lack of the theoretical basis. Therefore, based on the calculation model of the surrounding rock pressure of shallow buried tunnel, this paper analyzed the stability of the tunnel face and the vault and then obtained the calculation formula of the unsupported span of the shallow buried tunnel in soft rock stratum. It was pointed out that the unsupported span is not determined by the arch crown stability or the tunnel face stability alone, but by both. The rationality of the formula was verified by a centrifugal test and an engineering case. The analysis and discussion showed that the unsupported span is sensitive to the cohesion and internal friction angle of the rock-soil mass, especially the cohesion. The unsupported span of the shallow buried tunnel in the soft rock stratum is a linear function of the support pressure. The support pressure has a more significant contribution to the increase of the unsupported span by the centre cross diaphragm (CRD) method, and the unsupported span increases linearly with the increase of the support pressure. The research results provide a theoretical reference for the determination of the unsupported span for the shallow tunnel in the soft stratum.

Effect of groundwater on the displacements of axially loaded pile in clayey soil

2021 ◽  
Author(s):  
Tawfek Sheer Ali ◽  
Nassr Salman ◽  
Mohammed K. Fakhraldin
Keyword(s):  
Theoretical Study ◽  
Clayey Soil ◽  
Ground Surface ◽  
Horizontal Displacement ◽  
Soil Mass ◽  
Concrete Piles ◽  
Finite Element Package ◽  
Different Levels ◽  
Plaxis 3D ◽  
Horizontal Displacements

Abstract The displacement of a loaded pile could be vertical (axial) or horizontal (lateral); these displacements are sensitive to groundwater presence within the soil mass. This paper presents a theoretical study to investigate vertical and horizontal displacement of piles embedded in a clayey soil for different levels of groundwater under the ground surface. The study was performed using the commercial finite element package PLAXIS-3D. Three diameters of the concrete piles were considered: 0.5, 0.75 and 1 m, and were subjected to 1,000 kN axial load. The effect of 0, 5, 10, 15 and 20 m groundwater along the 20 m pile in length from the ground surface on the vertical and horizontal displacements was investigated. The results indicated that the vertical and horizontal displacements increase when the ground water level increases towards the base of pile. Also, there is a significant increase in the horizontal displacement up to 15 m of groundwater level from ground surface and decreased at levels from 15 to 20 m.

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