The Deflection and Bending Moment of Existing Piles Influenced by Trenching Diaphragm Wall Panel(s)

2017 ◽  
pp. 1-15
Author(s):  
Ahmed Mohamed ◽  
Marawan Shahin ◽  
Herbert Klapperich
Keyword(s):  
Bending Moment ◽  
Diaphragm Wall ◽  
Wall Panel

scholarly journals Thermo-hydro-mechanical coupling analysis of a thermo-active diaphragm wall

2018 ◽  
Vol 55 (5) ◽  
pp. 720-735 ◽  
Author(s):  
Yi Rui ◽  
Mei Yin
Keyword(s):  
New Technologies ◽  
Bending Moment ◽  
Diaphragm Wall ◽  
Elastic Model ◽  
Element Analysis ◽  
Thermally Induced ◽  
Mechanical Coupling ◽  
Reversal Effect ◽  
Earth Pressures ◽  
Geotechnical Aspect

Thermo-active diaphragm walls that combine load bearing ability with a ground source heat pump (GSHP) are considered to be one of the new technologies in geotechnical engineering. Despite the vast range of potential applications, current thermo-active diaphragm wall designs have very limited use from a geotechnical aspect. This paper investigates the wall–soil interaction behaviour of a thermo-active diaphragm wall by conducting a thermo-hydro-mechanical finite element analysis. The GSHP operates by circulating cold coolant into the thermo-active diaphragm wall during winter. Soil contraction and small changes in the earth pressures acting on the wall are observed. The strain reversal effect makes the soil stiffness increase when the wall moves in the unexcavated side direction, and hence gives different trends for long-term wall movements compared to the linear elastic model. The GSHP operation makes the wall move in a cyclic manner, and the seasonal variation is approximately 0.5–1 mm, caused by two factors: the thermal effects on the deformation of the diaphragm wall itself and the thermally induced volume change of the soil and pore water. In addition, it is found that the change in bending moment of the wall due to the seasonal GSHP cycle is caused mainly by the thermal differential across the wall during the winter, because the seasonal changes in earth pressures acting on the diaphragm wall are very limited.

Observed performance of a short diaphragm wall panel

Géotechnique ◽  
1999 ◽  
Vol 49 (5) ◽  
pp. 681-694 ◽  
Author(s):  
C. W. W. Ng ◽  
D. B. Rigby ◽  
G. H. Lei ◽  
S. W. L. Ng
Keyword(s):  
Diaphragm Wall ◽  
Wall Panel

An explicit analytical solution for calculating horizontal stress changes and displacements around an excavated diaphragm wall panel

2003 ◽  
Vol 40 (4) ◽  
pp. 780-792 ◽  
Author(s):  
C WW Ng ◽  
G H Lei
Keyword(s):  
Analytical Solution ◽  
Uniaxial Stress ◽  
Horizontal Stress ◽  
Ease Of Use ◽  
Elastic Solution ◽  
Diaphragm Wall ◽  
Wall Panel ◽  
Principle Of Superposition ◽  
Explicit Analytical Solution ◽  
Stress Changes

A new, simple, and explicit analytical solution has been derived for calculating horizontal stress changes and displacements caused by the excavation for a diaphragm wall panel. The theoretical solution is obtained by applying the principle of superposition appropriately to model diaphragm wall construction using a basic elastic solution to the problem of an infinite horizontal plate with a rectangular opening subjected to a uniaxial stress at infinity. The basic elastic solution can be obtained by using the method of complex variables with a simplified conformal transformation function. Key parameters governing the magnitude of horizontal stress changes and displacements are identified. Computed results are given in a normalized form in terms of aspect ratio (length to width) of a diaphragm wall panel. Two extreme cases for diaphragm wall panels with dimensions 1 m × 1 m and 10 m × 1 m have been analysed to investigate the distributions of stress changes and deformations around the panels during the bentonite stage. By performing a parametric study, calculation charts have been developed for computing horizontal stress changes and displacements for practising engineers and researchers to carry out preliminary designs and for numerical modellers to verify their sophisticated predictions. The ease of use of the charts is illustrated by two examples, and the limitations of the derived solutions are discussed.Key words: diaphragm wall, elasticity, stress change, displacement, stress analysis, earth pressure.

Deformation characteristics of a 38 m deep excavation in soft clay

2011 ◽  
Vol 48 (12) ◽  
pp. 1817-1828 ◽  
Author(s):  
Guo B. Liu ◽  
Rebecca J. Jiang ◽  
Charles W.W. Ng ◽  
Y. Hong
Keyword(s):  
Soft Clay ◽  
Field Performance ◽  
Lateral Wall ◽  
Diaphragm Wall ◽  
Deep Excavation ◽  
Wall Panel ◽  
Soft Clays ◽  
Measured Ratio ◽  
Increasing Demand ◽  
Ground Settlements

To meet the increasing demand for underground space for economical development and infrastructural needs, more and more deep excavations have been constructed in Shanghai. In this paper, field performance of a 38 m deep multistrutted excavation in Shanghai soft clay is reported. The deep excavation was retained by a 65 m deep diaphragm wall. Inclinometers as well as settlement and heave markers were installed to monitor the performance of the deep excavation. This project provides an unusual opportunity to study the differential heaves of center columns and diaphragm walls during excavation. Because of the significant stress relief resulting from the 38 m deep excavation, maximum heaves of the center column and diaphragm wall panel were about 30 and 16 mm, respectively. The measured ratio δp/H (heave/final excavation depth) of column is less than 0.1% whereas the observed δp/H of the diaphragm wall panel is about 0.04%. The maximum distortion between the column and the diaphragm wall panel is smaller than 1/500, which is within the limit range proposed by Bjerrum in 1963. Owing to careful construction control, stiff strutting system, and compaction grouting, the measured lateral wall deflections and ground settlements at this site are generally smaller than other shallower excavations in soft clays in Shanghai, Singapore, and Taipei.

scholarly journals MECHANICAL PERFORMANCE OF COMPOSITE RETAINING AND PROTECTION STRUCTURE FOR SUPER LARGE AND DEEP FOUNDATION EXCAVATIONS

2019 ◽  
Vol 25 (5) ◽  
pp. 431-440 ◽  
Author(s):  
Zhen Cui ◽  
Qimin Li ◽  
Jian Wang
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Performance ◽  
Lateral Displacement ◽  
Bending Moment ◽  
In Situ Monitoring ◽  
Diaphragm Wall ◽  
Stress System ◽  
Deep Foundation ◽  
Retaining Structure

The reliable retaining methods and a good stress system are the key to the success of super large and deep excavation engineering. In this paper, the deepest foundation pit in Hainan province is taken as an example. The method of mutual verification between in-situ monitoring and numerical simulation is adopted. The mechanical performance of composite retaining structure composed of reinforced concrete cast-in-situ soldier pile wall, diaphragm wall and prestressed anchor cable are studied. The interaction between the reinforced concrete cast-in-situ pile retaining structure at the upper part and the diaphragm wall retaining structure at the lower part is revealed, and the variation of internal forces of the diaphragm wall retaining structure in the time and space is demonstrated. And then the influence of insertion ratio and rigidity on the mechanical properties of diaphragm wall is discussed. Research shows, the range of interaction between the upper and lower retaining structures is limited. During the excavation process, the maximum bending moment of the diaphragm wall is always near the excavation surface, and the curvature of the bending moment curve decreases gradually with the increase of excavation depth and axial tension of anchor. When the insertion ratio of diaphragm wall increases, the maximum bending moment moves upward. With the rigidity of the diaphragm wall increases moderately, the bending moment of the retaining structure increases, but the lateral displacement decreases. The research results can provide theoretical basis and practical experience for the composite retaining structure design of super large and deep foundation excavations.

Analysis of Mechanical Behavior of Subway Tunnel Constructed by Cover and Cut Reverse Method

2012 ◽  
Vol 446-449 ◽  
pp. 3623-3627
Author(s):  
Tie Cheng Wang ◽  
Yang Gao ◽  
Hai Long Zhao
Keyword(s):  
Bending Moment ◽  
Horizontal Displacement ◽  
Internal Force ◽  
Surrounding Rock ◽  
Diaphragm Wall ◽  
Tunnel Construction ◽  
Construction Process ◽  
Subway Tunnel ◽  
Diaphragm Walls ◽  
Reverse Method

In the paper, not only the internal force and displacement of structure during subway tunnel construction with cover and cut reverse method, but also the displacement field and stress field of surrounding rock are analysed. From the numerical calculation it is shown that the bending moment of diaphragm wall is affected seriously by the distribution and value of the stiffness of horizontal support; the excavation phase of the soil of the second floor underground is the key phase of the construction process because the internal force of structure has large increase; the value of surface settlement, horizontal displacement of diaphragm wall, differential settlement between middle pillar and diaphragm walls all meet the requirements, so the construction is safe and the surrounding buildings are affected slightly.

scholarly journals Experimental and Numerical Investigation on the Effects of Foundation Pit Excavation on Adjacent Tunnels in Soft Soil

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zi-Tian Yu ◽  
Heng-Yu Wang ◽  
Wenjun Wang ◽  
Dao-Sheng Ling ◽  
Xue-Dong Zhang ◽  
...  
Keyword(s):  
Retaining Wall ◽  
Soft Soil ◽  
Shear Bands ◽  
Earth Pressure ◽  
Bending Moment ◽  
Surface Settlement ◽  
Diaphragm Wall ◽  
Foundation Pit ◽  
Obvious Effect ◽  
Diaphragm Walls

Excavations near an existing tunnel are often encountered in underground construction. The influence of the excavation on the adjacent tunnels is not yet fully understood. This study presented a centrifugal model test about excavation next to existing tunnels in soft soil foundation. The bending moment of diaphragm wall, surface settlement, tunnel deformation, and earth pressure around the tunnel were mainly studied. The influence of tunnel location is further studied by numerical simulation. During the stabilization stage of foundation pit, the diaphragm walls present convex deformation towards foundation pit, and the surface settlement outside the diaphragm wall appears to be the concave groove type. During the overexcavation stage, the diaphragm walls are almost damaged, and the shear bands are nearly tangent to the tunnels. The displacement of the tunnels and the surface settlement rapidly increase. The deformation of the diaphragm wall and the surface settlement are limited by the existing tunnel. The numerical results indicate that the change of tunnel location has little effect on the retaining wall but an obvious effect on the tunnel itself.

Study on Influencing Factors and Control Measures of Diaphram Wall Panel Trench

2012 ◽  
Vol 535-537 ◽  
pp. 1851-1854
Author(s):  
Jun Zhang ◽  
Huie Chen ◽  
Cheng Qiu Cai ◽  
Ming Yuan Shi ◽  
Huan Yan ◽  
...  
Keyword(s):  
Influencing Factors ◽  
Control Measures ◽  
Diaphragm Wall ◽  
Wall Panel ◽  
Key Factors ◽  
Foundation Construction ◽  
Deformation Control ◽  
Slurry Wall ◽  
The Stability ◽  
And Control

The stability of the slurry wall in the process of slurry supporting into slot directly affects the stability of the pit. This paper analyzes the key factors for deformation control, researches the influencing factors on slurry wall stability during slurry trenching and concreting for diaphragm wall, and proposes control measures to control the stability of slurry wall and matters need attention, which is of great significance to guide the foundation construction.

scholarly journals The influence of the parameters of the diaphragm wall on the deformation of the excavation

2020 ◽  
Vol 198 ◽  
pp. 02013
Author(s):  
Peng-fei CHEN ◽  
Xiao-nan GONG
Keyword(s):  
Elastic Modulus ◽  
Wall Thickness ◽  
Retaining Wall ◽  
Bending Moment ◽  
Variable Method ◽  
Diaphragm Wall ◽  
Comparison Result ◽  
Plaxis 3D

A model of a certain excavation was established using PLAXIS 3D, and the measured value was compared with the calculated value. The thickness, elastic modulus, and embedded depth of the diaphragm wall are analysed by the controlled variable method. The graphs of the influence of the above three factors on the deformation of the retaining wall of the excavation, the settlement of the soil outside the pit, and the bending moment of the retaining wall are obtained. The data is relativized to make the comparison result more intuitive and vivid. With the increase of wall thickness or elastic modulus or embedded depth, the deformation of the retaining wall and the settlement of the soil outside the pit will decrease. As the wall thickness or elastic modulus increases, the bending moment of the retaining wall will increase. The embedded depth has almost no effect on the bending moment. The magnitude of the influence on the deformation and force of the excavation is sorted from the largest to the smallest as the wall thickness, the elastic modulus, and the embedded depth.

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