Monitoring of Large Section Tunnel Crossing Qiantang River during Operation Period

2012 ◽  
Vol 226-228 ◽  
pp. 1517-1523 ◽  
Author(s):  
Guan Shui Liu ◽  
Zong Liang Li ◽  
Shi Ming Wu ◽  
Lu Qing Yu
Keyword(s):  
Pressure Distribution ◽  
Large Diameter ◽  
Great Influence ◽  
Earth Pressure ◽  
Soil Disturbance ◽  
Large Section ◽  
Qiantang River ◽  
Operation Period ◽  
Sandy Substratum ◽  
Short Time

The foreign precision monitoring equipment was used for long term health monitoring in the large diameter tunnel of Hangzhou Qingchun-road. Based on field monitoring data, the force and deformation of the large section crossing-river tunnel during operation period were summarized and analyzed. A detailed analysis of the effect of tide and scour on the tunnel interface force and tunnel settlement were given. Data shows accumulations of both longitudinal settlement of tunnel segments and the earth pressure distribution around the tunnel lining under the loads of both traffic and tide which results in soil disturbance in the construction period. The settlement becomes stable after about six months. The substratum has a great influence on the longitudinal settlement of tunnel segments. The settlement of tunnel invert in sandy substratum is obviously affected by the tide of Qiantang River for short time, while slight changes appear in the deformation of tunnel diameter, stress of steel bar and earth pressure distribution.

Field Performance and Analysis of 3-m-Diameter Induced Trench Culvert under a 19.4-m Soil Cover

2008 ◽  
Vol 2045 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Bethanie A. Parker ◽  
Rodney P. McAffee ◽  
Arun J. Valsangkar
Keyword(s):  
Pressure Distribution ◽  
Earth Pressure ◽  
Field Performance ◽  
Overburden Pressure ◽  
Vertical Pressure ◽  
Earth Pressures ◽  
Design Loads ◽  
Horizontal Pressure ◽  
Two Stages

An induced trench installation was instrumented to monitor earth pressures and settlements during construction. Some of the unique features of this case study are as follows: (a) both contact and earth pressure cells were used; (b) part of the culvert is under a new embankment and part was installed in a wide trench within an existing embankment; (c) a large stockpile was temporarily placed over the induced trench; and (d) the compressible material was placed in two stages. The maximum vertical pressure measured in the field at the crown of the culvert was 0.24 times the overburden pressure. The maximum horizontal pressure measured on the side of the culvert at the springline was 0.45 times the overburden pressure. The column of soil directly above the compressible zone settled approximately 40% more than did the adjacent fill. The field results at the crown and springline compared reasonably with those observed with numerical modeling. However, the overall pressure distribution on the pipe was expected to be nonuniform, the average vertical pressure calculated by using numerical analysis on top of the culvert over its full width was 0.61 times the overburden pressure, and the average horizontal pressure calculated on the side of the culvert over its full height was 0.44 times the overburden pressure. When the full pressure distribution on the pipe is considered, the recommended design loads from the Marston–Spangler theory slightly underpredict the maximum loads, and the vertical loads control the design.

scholarly journals Mathematical description of a bounded oil reservoir with a horizontal well

2021 ◽  
Vol 2 (1) ◽  
pp. 67-76
Author(s):  
T. N. Nzomo ◽  
S. E Adewole ◽  
K. O Awuor ◽  
D. O. Oyoo
Keyword(s):  
Pressure Distribution ◽  
Effective Permeability ◽  
Horizontal Well ◽  
Horizontal Wells ◽  
Oil Reservoir ◽  
Vertical Wells ◽  
Anisotropic Permeability ◽  
Time Approximation ◽  
Reservoir Geometry ◽  
Short Time

Horizontal wells are more productive compared to vertical wells if their performance is optimized. For a completely bounded oil reservoir, immediately the well is put into production, the boundaries of the oil reservoir have no effect on the flow. The pressure distribution thus can be approximated with this into consideration. When the flow reaches either the vertical or the horizontal boundaries of the reservoir, the effect of the boundaries can be factored into the pressure distribution approximation. In this paper we consider the above cases and present a detailed mathematical model that can be used for short time approximation of the pressure distribution for a horizontal well with sealed boundaries. The models are developed using appropriate Green’s and source functions. In all the models developed the effect of the oil reservoir boundaries as well as the oil reservoir parameters determine the flow period experienced. In particular, the effective permeability relative to horizontal anisotropic permeability, the width and length of the reservoir influence the pressure response. The models developed can be used to approximate and analyze the pressure distribution for horizontal wells during a short time of production. The models presented show that the dimensionless pressure distribution is affected by the oil reservoir geometry and the respective directional permeabilities.

scholarly journals An Efficient Time Reversal Method for Lamb Wave-Based Baseline-Free Damage Detection in Composite Laminates

2018 ◽  
Vol 9 (1) ◽  
pp. 11 ◽  
Author(s):  
Liping Huang ◽  
Junmin Du ◽  
Feiyu Chen ◽  
Liang Zeng
Keyword(s):  
Damage Detection ◽  
Time Reversal ◽  
Lamb Wave ◽  
Composite Laminates ◽  
Narrow Band ◽  
Great Influence ◽  
Time Intervals ◽  
Wide Range ◽  
Reconstructed Signal ◽  
Short Time

Time reversal (TR) concept is widely used for Lamb wave-based damage detection. However, the time reversal process (TRP) faces the challenge that it requires two actuating-sensing steps and requires the extraction of re-emitted and reconstructed waveforms. In this study, the effects of the two extracted components on the performance of TRP are studied experimentally. The results show that the two time intervals, in which the waveforms are extracted, have great influence on the accuracy of damage detection of the time reversal method (TRM). What is more, it requires a large number of experiments to determine these two time intervals. Therefore, this paper proposed an efficient time reversal method (ETRM). Firstly, a broadband excitation is applied to obtain response at a wide range of frequencies, and ridge reconstruction based on inverse short-time Fourier transform is applied to extract desired mode components from the broadband response. Subsequently, deconvolution is used to extract narrow-band reconstructed signal. In this method, the reconstructed signal can be easily obtained without determining the two time intervals. Besides, the reconstructed signals related to a series of different excitations could be obtained through only one actuating-sensing step. Finally, the effectiveness of the ETRM for damage detection in composite laminates is verified through experiments.

scholarly journals Effect of Voids behind Lining on the Failure Behavior of Symmetrical Double-Arch Tunnels

Symmetry ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1321 ◽  
Author(s):  
Zhang ◽  
Ye ◽  
Min ◽  
Xu
Keyword(s):  
Service Life ◽  
Earth Pressure ◽  
Internal Force ◽  
Failure Behavior ◽  
Large Section ◽  
Failure Patterns ◽  
Internal Forces ◽  
Tunnel Safety ◽  
Increasing Demand ◽  
The Impact

The presence of voids behind lining seriously affects the safety of the symmetrical double-arch tunnels during service life. It is essential to find out the impact of voids on tunnel safety due to the increasing demand for the construction and maintenance of symmetrical double-arch tunnels. Model tests and numerical analyses were conducted in this research. The results attained were explored including earth pressure, internal force, and lining failure. Results reveal that the presence of voids has a large influence on the internal force in the lining of symmetrical double-arch tunnels, generally in the form of asymmetrical failure patterns of the lining. The failure patterns of the lining are greatly influenced by the size and location of voids with respect to the symmetrical double-arch tunnel circumference. Significant changes in the lining internal forces were found at the areas in the close vicinity of the void whereas a few changes were found at the bottom of the sidewall, the invert, and the central wall far away from the void. The propagation laws of lining cracks of asymmetrical double-arch tunnels are more complicated than symmetrical tunnels with a void behind the central wall. The location of the initial cracking of symmetrical and asymmetrical double-arch tunnels is the same, while the lining failure of the large-section tunnel is the most complicated.

The equivalence of a jointed shield-driven tunnel lining to a continuous ring structure

2001 ◽  
Vol 38 (3) ◽  
pp. 461-483 ◽  
Author(s):  
K M Lee ◽  
X W Ge
Keyword(s):  
Pressure Distribution ◽  
Joint Stiffness ◽  
Earth Pressure ◽  
Horizontal Displacement ◽  
Internal Force ◽  
Ring Structure ◽  
Tunnel Lining ◽  
Bending Rigidity ◽  
Continuous Ring ◽  
Soft Clays

This paper presents a new method of determining the correction factor to approximate a jointed, shield-driven tunnel lining as a continuous ring structure under plane strain conditions. An earth pressure distribution pattern is proposed which is developed based on the long-term behavior of shallow tunnels constructed in soft clays as observed in the field. The "force method" was used to determine the internal forces and displacements of jointed, shield-driven tunnels. Either the vertical or the horizontal displacement of the tunnel lining can be used as a common matching parameter. Factors such as joint stiffness, soil resistance, joint distribution, number of joints, and tunnel geometry can be considered by the proposed method. Simplified design equations for the estimation of equivalence factors are also proposed for the typical tunnel lining geometry of urban subway tunnels. The proposed equivalence method was evaluated by comparing it with the results of laboratory tests.Key words: shield-driven tunnel, jointed segmental lining, effective bending rigidity ratio, equivalence factor, lining internal force, earth pressure distribution.

Field performance, centrifuge testing, and numerical modelling of an induced trench installation

2008 ◽  
Vol 45 (1) ◽  
pp. 85-101 ◽  
Author(s):  
Rodney P. McAffee ◽  
Arun J. Valsangkar
Keyword(s):  
Numerical Modelling ◽  
Pressure Distribution ◽  
Earth Pressure ◽  
Field Performance ◽  
Overburden Pressure ◽  
Centrifuge Testing ◽  
Geotechnical Centrifuge ◽  
Earth Pressures ◽  
Prototype Structure ◽  
Box Culvert

The field performance of an induced trench installation is compared to the results of centrifuge testing and numerical modelling. The measured vertical pressure at the crown of the pipe in the field ranged from 0.24 to 0.36 times the overburden pressure. The horizontal earth pressures measured in the field at the springline level determined a coefficient of lateral earth pressure between 0.39 and 0.49. The culvert was monitored over a period of 2 years following completion of embankment construction indicating no measurable changes in earth pressures and deformations. A model box culvert simulating the prototype height of soil cover, the pipe width, and the thickness of the compressible layer was tested using a geotechnical centrifuge. The prototype structure was also evaluated using numerical modelling to predict full earth pressure distribution and deformations. A comparison of field data, centrifuge testing, and numerical modelling shows that the Marston–Spangler theory used in designing induced trench culverts is conservative. The theory however, does not address or predict the nonuniform pressures on the top, sides, or bottom of the pipe, and therefore numerical analysis should be used to estimate the complete pressure distribution.

scholarly journals Parametric Study of Sheet Pile Wall using ABAQUS

2021 ◽  
Vol 7 (1) ◽  
pp. 71-82
Author(s):  
Taku Muni ◽  
Dipika Devi ◽  
Sukumar Baishya
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Distribution ◽  
Earth Pressure ◽  
Sheet Pile ◽  
Passive Earth Pressure ◽  
Element Analysis ◽  
The Earth ◽  
Wall Deformation ◽  
Sheet Pile Wall

In the present study two-dimensional finite element analysis has been carried out on cantilever sheet pile wall using ABAQUS/Standard software to study the effect of different friction angles and its related parameters such as dilation angle, the interfacial friction coefficient between soil-wall on earth pressure distribution, and wall deformation. From the results obtained, it is found that there is a significant decrease in wall deformation with an increase in the angle of internal friction and its related parameters. The earth pressure results obtained from the finite element analysis shared a unique relationship with that of a conventional method. Both the results showed similar linear behavior up to a certain percentage of wall height and then changed drastically in lower portions of the wall. This trend of behavior is seen in both active as well as in passive earth pressure distribution for all the frictional angle. Hence, after comparing the differences that exist in the results for both methods, from the analysis a new relationship between the earth pressure coefficients from a conventional method and the finite element method has been developed for both active and passive earth pressure on either side of the sheet pile wall. This relationship so derived can be used to compute more reasonable earth pressure distributions for a sheet pile wall without carrying out a numerical analysis with a minimal time of computation. And also the earth pressure coefficient calculated from this governing equation can serve as a quick reference for any decision regarding the design of the sheet pile wall. Doi: 10.28991/cej-2021-03091638 Full Text: PDF

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