scholarly journals Parametric Sensitivity Study of Deep Excavation in Singapore Old Alluvium Formation

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Lanting Wu ◽  
Jianping Sun ◽  
Yuqiang Tong
Keyword(s):  
Ground Improvement ◽  
Retaining Wall ◽  
Soil Layer ◽  
Bending Moment ◽  
Sensitivity Study ◽  
Design Parameters ◽  
Deep Excavation ◽  
System Sensitivity ◽  
Wall Deflection ◽  
Underground Infrastructure

Deep excavation supported by vertical retaining walls together with strutting system is commonly used in Singapore for the construction of underground infrastructure. In this paper, a series of numerical scenarios simulated by PLAXIS software are carried out to study the influence of different design parameters such as pre-auger loosening effect, the embedded depth of retaining wall into the stiff soil layer, and the elastic modulus of the ground improvement layer on excavation design especially on strut force, retaining wall deflection, and bending moment. The results show that there is high risk if only a single set of parameters are used as input to predict the performance of the retaining system. Sensitivity analysis shall be carried out to evaluate the effects of these parameter variations within a reasonable range on strut force, retaining wall deflection, and bending moment.

scholarly journals Numerical Analysis on the Performance of the Underwater Excavation

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Bo Li ◽  
Cangqin Jia ◽  
Guihe Wang ◽  
Jun Ren ◽  
Gaofeng Lu ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Retaining Wall ◽  
Lateral Wall ◽  
Surface Settlement ◽  
Design Parameters ◽  
Analysis Model ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Wall Deflection ◽  
Total Settlement

Based on the Yongdingmen Station of Beijing Metro, the underwater excavation method for deep foundation pit was introduced. This study constructed a numerical analysis model to analyze the performance of surface settlement and lateral wall deflection in the process of underwater excavation. Results showed that this method was better to control the surface settlement and lateral wall deflection compared with other dewatering excavations. In detail, most of the surface settlement was caused during the dry excavation stage and dewatering excavation stage while the deflection caused by underwater excavation only accounted for about 10% of the total settlement. Besides, the maximum settlement occurred 0.25∼0.5 H e behind the retaining wall and the value was 0.04% H e . Similar to the result of the surface settlement, most of the lateral wall deflection had been completed before the underwater excavation, which only caused about 7% of the total deflection. The maximum wall deflection and its location were approximately 0.06% H e and 0.5 H e , respectively. Moreover, a series of 3D numerical analyses were studied on the design parameters of the underwater excavation method. This study can be used as a reference for general performance and structural design of foundation pits with underwater excavation.

scholarly journals The Diaphragm Wall Deflection Simulation Project was Tested in Ho Chi Minh City, Vietnam

2021 ◽  
Vol 9 (7) ◽  
pp. 902-907
Keyword(s):  
Retaining Wall ◽  
Retaining Walls ◽  
Ho Chi Minh City ◽  
Deep Excavation ◽  
Concrete Wall ◽  
Wall Deflection ◽  
Reinforced Concrete Wall ◽  
Lateral Displacements ◽  
The Stability ◽  
Element Technique

Checking and calculating the stability of retaining walls and deep excavation are required in the design and construction of subterranean structures, particularly the DW500 reinforced concrete Wall-Plate. This is one of the most significant approaches to preventing landslides and settlement for buildings in the immediate vicinity. In fact, calculating and forecasting the DW500 retainer wall's stability and determining the influent area can provide a variety of options for reducing reinforced frame parts (retaining wall and shoring). This technology is now being explored and used for the most realistic structures in Vietnam, particularly in Ho Chi Minh City. This article uses the finite element technique (FEM –Plaxis 2D-2019) to calculate the lateral displacements, shoring, and outer foundation for the DW500 retaining wall.

scholarly journals Comparison of Induced Deflection and Forces in Piles Adjacent to Tunnelling and Deep Excavation in 2D and 3D Problems

2018 ◽  
Vol 203 ◽  
pp. 04011
Author(s):  
Ong Yin Hoe ◽  
Hisham Mohamad
Keyword(s):  
Bending Moment ◽  
Pile Group ◽  
3D Models ◽  
Deep Excavation ◽  
Pile Groups ◽  
Out Of Plane ◽  
National University ◽  
Plane Direction ◽  
2D And 3D ◽  
2D Model

There is a trend in Malaysia and Singapore, engineers tend to model the effect of TBM tunneling or deep excavation to the adjacent piles in 2D model. In the 2D model, the pile is modelled using embedded row pile element which is a 1-D element. The user is allowed to input the pile spacing in out-of-plane direction. This gives an impression to engineers the embedded pile row element is able to model the pile which virtually is a 3D problem. It is reported by Sluis (2014) that the application of embedded pile row element is limited to 8D of pile length. It is also reported that the 2D model overestimates the axial load in pile and the shear force and bending moment at pile top and it is not realistic in comparison to 3D model. In this paper, the centrifuge results of single pile and 6-pile group - tunneling problem carried out in NUS (National University of Singapore) are back-analysed with Midas GTS 3D and a 2D program. In a separate case study, pile groups adjacent to a deep excavation is modelled by 3D and 2D program. This paper compares the deflection and forces in piles in 2D and 3D models.

scholarly journals Adopting Numerical Models for Prediction of Ground Movements Induced by Deep Excavation

2020 ◽  
Vol 8 (6) ◽  
pp. 976-989
Keyword(s):  
Numerical Models ◽  
Ground Surface ◽  
Sensitivity Study ◽  
Design Criterion ◽  
Deep Excavation ◽  
Soil Behavior ◽  
Analysis And Design ◽  
Ground Movements ◽  
Codes Of Practice ◽  
Adjacent Structures

Control of ground surface settlement induced by deep excavation is of major concern in order to attain safety of adjacent structures and utilities against excessive or differential settlements. Accurate prediction of ground surface movements is an important design criterion in the analysis and design of excavation supporting systems. Many codes of practice are based on a design criterion that satisfies a factor of safety preventing collapse of the system and its surrounding soil. In this research, finite element modeling is adopted to numerically simulate the performance of deep excavation systems and the associated ground movements. The soil behavior was simulated using two types of models; the Mohr-Coulomb model (MC) and the Hardening Soil Model (HS). Field data from monitoring a real deep excavation case history of a retaining system was considered to check the validity of the proposed numerical modeling. A simpler equivalent section replacing the multi-layered soil profile was verified. Then, a sensitivity study has been conducted to study the influence of major parameters that affect ground movements induced by deep excavation. The results of the parametric study were accomplished to construct design charts and drive empirical equations by implementing a design parameter, called the "Stiffness Ratio (R)”, that represents the supporting system stiffness. From these suggested charts and equations, the percentage of maximum vertical ground movements to wall height can be estimated.

scholarly journals Dynamic Analysis and Structure Soil Interaction of Retaining Wall Using ETABS

2018 ◽  
Vol 7 (3.10) ◽  
pp. 50
Author(s):  
T Subramani ◽  
E Narendra Kumar
Keyword(s):  
Dynamic Analysis ◽  
Seismic Response ◽  
Retaining Wall ◽  
Soil Layer ◽  
Complex Problem ◽  
Dynamic Conditions ◽  
The Past ◽  
Dynamic Traits

Retaining systems are widely used international for serving numerous functions in structures and infrastructures. The seismic response of forms of walls that assist a single soil layer has been examined with the aid of some of researchers in the past. The design of preserving partitions in seismic areas poses a complex problem. The conventional layout method usually contains calculation of an element of safety in opposition to sliding, overturning and bearing ability failure. Retaining partitions have suffered damages under beyond earthquakes. Typically the analyses do not bear in mind the retained soil’s interplay with the wall, which takes location at some point of dynamic conditions. The situations of separation of wall (at some point of interactions) over again trade the dynamic traits of the assumed wall-soil interplay that needs to be addressed. Our study conducts the retaining wall beneath static in addition to seismic situations about above components.  

The Force Analysis of Anchor Anti-Slide Pile in Slope Reinforcement under Seismic Load

2015 ◽  
Vol 777 ◽  
pp. 148-153
Author(s):  
Hui Ding ◽  
Jie Chen ◽  
Li Song
Keyword(s):  
Dynamic Analysis ◽  
Seismic Wave ◽  
Contact Stress ◽  
Dynamic Performance ◽  
Bending Moment ◽  
Dynamic Contact ◽  
Design Parameters ◽  
Seismic Load ◽  
Slope Reinforcement ◽  
Earthquake Action

The force affect factors of anchor anti-slide pile in slope reinforcement under seismic load are studied in this paper. First of all, the method of dynamic analysis is introduced in FLAC3D. At the same time, seismic wave is selected in seismic dynamic analysis. Then, the sensitivity influence of anti-slide pile design parameters on dynamic contact stress, shear force and dynamic bending moment is analyzed by applying the seismic wave, giving the most significant effect factors of the dynamic contact stress and dynamic moment. In the end, the distribution regular of the contact force and the pile body stress under earthquake action is analyzed by selecting a case, laying a theoretical foundation for the further study of the dynamic performance of the reinforced slope.

Sensitivity Study of Critical Parameters Influencing the Uncertainty of Fatigue Damage in Steel Catenary Risers

2010 ◽  
Author(s):  
Feng Zi Li ◽  
Ying Min Low
Keyword(s):  
Fatigue Damage ◽  
Cost Effective ◽  
Sensitivity Study ◽  
Structural Safety ◽  
Critical Parameters ◽  
Design Parameters ◽  
Steel Catenary Riser ◽  
Bending Stresses ◽  
Steel Catenary Risers ◽  
Touchdown Point

The most challenging aspect of a deepwater development is the riser system, and a cost-effective choice is the Steel Catenary Riser (SCR). Fatigue is often a governing design consideration, and it is usually most critical at the touchdown point (TDP) where static and dynamic bending stresses are highest. Unfortunately, it is also at this region that uncertainty is the maximum. The increased uncertainty casts doubt on the applicability of generic safety factors recommended by design codes, and the most consistent way of ensuring the structural safety of the SCR is to employ a reliability-based approach, which has so far not received attention in SCR design. As the number of basic random variables affects the complexity of a reliability analysis, these variables should be selected with caution. To this end, the aim of this paper is to draw up a comprehensive list of design parameters that may contribute meaningfully to the uncertainty of the fatigue damage. From this list, several parameters are selected for sensitivity studies using the commercial package Orcaflex. It is found that variations in seabed parameters such as soil stiffness, soil suction and seabed trench can have a pronounced influence on the uncertainty of the fatigue damage at the touchdown point.

Calculation of Retaining Walls with Anchoring at Different Levels

2015 ◽  
Vol 725-726 ◽  
pp. 185-189
Author(s):  
Alexey Melentev ◽  
Vladimir Korovkin
Keyword(s):  
Lateral Pressure ◽  
Retaining Wall ◽  
Bending Moment ◽  
Retaining Walls ◽  
Neutral Axis ◽  
Plastic Yielding ◽  
Optimal Production ◽  
Upper Limit ◽  
Different Levels ◽  
Practical Recommendations

Shows the proposed method for the calculation of mirroring duhaney retaining wall. This method is through the use of multiple design schemes can more accurately determine the lateral pressure on the wall, given compliance supports. In this case, the bending moment diagram in the wall and supports efforts depend on the variable diagrams of lateral pressure on the wall associated with the position of the line relative to its elastic neutral axis. Given the uncertainty about the quantities displacement of supports, it is proposed to take into account the upper limit of the voltage equal to the appearance of the yield plateau in the anchor rod. In this case, the plastic yielding of the anchor rod to limit effort in it, due to the redistribution of stresses to the other rod. Practical recommendations for the optimal production of works in the construction of continuous dvuhankerny walls.

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