scholarly journals Predicting Response of Constructed Tunnel to Adjacent Excavation with Dewatering

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Panpan Guo ◽  
Feifei Liu ◽  
Gang Lei ◽  
Xian Li ◽  
Cheng-wei Zhu ◽  
...  
Keyword(s):  
Water Level ◽  
Shear Force ◽  
Bending Moment ◽  
Vertical Displacement ◽  
Internal Force ◽  
Specific Yield ◽  
Additional Stress ◽  
Initial Water ◽  
Plan View ◽  
Maximum Shear Force

This paper proposes a new method for predicting the displacement and internal force of constructed tunnels induced by adjacent excavation with dewatering. In this method, the total excavation-induced additional stress on the constructed tunnel is derived by superposing the additional stresses induced by excavation unloading and dewatering effects. The additional stress induced by unloading effect is calculated using Mindlin’s solution. The additional stress induced by dewatering effect is calculated using the principle of effective stress and the Dupuit precipitation funnel curve. With the beam on elastic foundation method, the total additional stress is then used for calculating the tunnel displacement and internal force caused by adjacent excavation with dewatering. Based on three well-documented case histories, the performance of the proposed method is verified. Moreover, a parametric analysis is also performed to capture the effects of excavation depth, tunnel-to-excavation distance, initial water level, excavation plan view size, and specific yield on the responses of the constructed tunnels. The results indicate that the effect of excavation depth on the tunnel maximum vertical displacement, maximum bending moment, and maximum shear force is more significant at an excavation depth greater than the cover depth of the constructed tunnel. The tunnel maximum vertical displacement, maximum bending moment, and maximum shear force decrease nonlinearly with an increase in the tunnel-to-excavation distance and the initial water level. Among the investigated parameters, the excavation dimension in the tunnel longitudinal direction affects most the tunnel responses. The effect of specific yield on the tunnel displacement and internal force induced by adjacent excavation with dewatering becomes more obvious as increasing the initial water level and excavation depth.

Inner Force Analysis of Two Typical Frames with Vertical Displacement

2008 ◽  
Vol 400-402 ◽  
pp. 341-346
Author(s):  
Wei Zhou
Keyword(s):  
External Load ◽  
Bending Moment ◽  
Simple Calculation ◽  
Basic Structure ◽  
Vertical Displacement ◽  
Internal Force ◽  
Moment Redistribution ◽  
Calculation Results ◽  
Vertical Chain ◽  
Force Calculation

Finite element method is often used to obtain exact solution in the course of internal force calculation of some complex frames which contain nodal vertical displacement such as frames with transferring layer and mega-frames with sub-structure. In the phase of scheme comparison and schematic design, methods which can quickly produce calculation results of the above said frameworks are necessary. Based on the basic principle of displacement method, this paper proposes a simple analytical method for frameworks that contain nodal vertical displacement. According to the proposal, the basic structure for calculation is the framework in which is added vertical chain-pole at relevant node; the basic unknown quantities are the nodal vertical displacement of the basic structure; the basic equation is fixed according to the equilibrium of node forces; unit vertical displacement as well as bending moment and shear diagram of the basic structure under external load are respectively obtained by using moment redistribution method; nodal vertical displacement is determined through substitution of shear force of relevant rod into the equilibrium equation of the chain-pole node; the actual internal force is determined through superposition of actual vertical displacement and internal force diagram algebra of the basic structure under vertical external load. An engineering example is introduced, which is intended to provide reference for the simple calculation for the above said complex frameworks.

scholarly journals Development of a Manually Operated Hydraulic Press and Pull

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Bethrand N Nwankwojike ◽  
Chukwunonso N Nwogu ◽  
Godswill Kalu
Keyword(s):  
Shear Force ◽  
Bending Moment ◽  
Hydraulic Press ◽  
Hydraulic Pump ◽  
Maximum Displacement ◽  
Maximum Shear Force ◽  
Local Materials

A hydraulic press and pull machine comprising of a frame, cylinder and piston, two threaded studs, hydraulic pump and hose, pulling clamp and a workpiece support was designed, fabricated and evaluated. The machine is manually operated. The maximum shear force, maximum bending moment and maximum displacement of the machine workpiece support were determined as 74.9491N, 16.6335N-m and 4.367e3mm for a simulated load of 1000N. Maximum axial, bending and torsional stresses were also determined as 0.00359, 701998 and 0.00653N/m2 respectively. performance of the developed machine was determined using seven bearings of bore diameters 24, 30, 40, 50, 65, 80 and 100mm respectively, fitted into seven corresponding shafts with shaft deviation of ±0.001mm and dismantled afterwards using three different methods: traditional hammering, the developed manual hydraulic press and pull machine and already existing electrically powered hydraulic press. The results of the experiments showed that traditional hammering is the most time consuming method of mounting and dismounting force fits, followed by the use of the developed press-pull machine while electrically powered hydraulic presses are the fastest.The machine which was fabricated with local materials will reduce the time and stress associated with installation and removal of bearings, and other forms of force fits in machine assemblies. Hence, leading to an overall improvement in the standard of machines/equipment fabricated in Nigeria

scholarly journals Assessing the effect of governing parameters of bearing capacity determination of small piled rafts on clay soil

2021 ◽  
Vol 14 (22) ◽  
Author(s):  
Shivanand Mali ◽  
Baleshwar Singh
Keyword(s):  
Shear Force ◽  
Bending Moment ◽  
Pile Spacing ◽  
Piled Raft ◽  
Pile Diameter ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Maximum Shear Force ◽  
Settlement Ratio ◽  
Pile Length

Abstract In the present study, a small piled raft foundation has been simulated numerically through PLAXIS 3-D software. The objective of this study was to investigate the effect of governing parameters such as pile length, pile spacing, pile diameter, and number of piles on the settlement and load-bearing behavior of piled raft, so as to achieve the optimum design for small piled raft configurations. An optimized design of a piled raft is defined as a design with allowable center and differential settlements and satisfactory bearing behavior for a given raft geometry and loading. The results indicated that, with increase in pile length, pile spacing, pile diameter, and number of piles, both the center settlement ratio and differential settlement ratio decreased. The load-bearing capacity of piled raft increased with increase in pile length, pile spacing, pile diameter, and number of piles. Furthermore, the percentage load carried by the piles increased as the pile length, pile spacing, pile diameter, and number of piles increased. The bending moment and shear force in corner pile are noted to be more, and they decreased towards the center pile. With increase in pile length, the maximum raft bending moment decreased, whereas the maximum shear force in the raft increased. Further, with increase in pile spacing, pile diameter, and number of piles, the maximum bending moment and maximum shear force in the raft increased. The optimum parameters for the piled raft foundation can be selected efficiently with the consideration of maximum bending moment and maximum shear force while designing the piled raft foundation. Thus, the results of this study can be used as guidelines for achieving optimum design for small piled raft foundation.

scholarly journals Method to Control the Deformation of Anti-Slide Piles in Zhenzilin Landslide

2020 ◽  
Vol 10 (8) ◽  
pp. 2831 ◽  
Author(s):  
Hao Wang ◽  
Peng Wang ◽  
Hongyu Qin ◽  
Jianwei Yue ◽  
Jianwei Zhang
Keyword(s):  
Shear Force ◽  
Slip Surface ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Subgrade Reaction ◽  
Pile Head ◽  
Landslide Stability ◽  
Subsequent Decrease ◽  
Maximum Shear Force ◽  
Internal Forces

Anti-slide piles were used in the region of the Zhenzilin landslide in Sichuan, China. The horizontal displacement of these piles exceeds specifications. Deterioration in bedrock properties may cause deformation, thereby causing landslide destabilization. An approach was developed for the analysis of anti-slide pile in two bedrocks with different strengths below the slip surface. A relationship has been established between the modulus of subgrade reaction of the first weak bedrock and reasonable embedded length for landfill slopes with strata of various strengths. Furthermore, the influence of embedding length on deformation has been studied to determine the reasonable embedded length, which helps reduce deformation and ensure landslide stability. The results reveal that (1) at a constant embedded length, horizontal displacement increases with the thickness of the first soft bedrock, meanwhile the maximum shear force remains constant, and the bending moment first increases followed by subsequent decrease; (2) with an increase in the embedded length, horizontal displacement and the maximum shear force of the pile in the embedded bedrock decrease, whereas the bending moment increases; (3) the maximum internal forces and horizontal displacement increase with a decrease in the subgrade reaction modulus of the first weak rock; and (4) the reasonable embedded length of an anti-slide pile increases with a decrease in the subgrade reaction modulus of the first weak bedrock. The proposed approach can be employed to design anti-slide piles in similar landslide regions to control pile-head deformation.

Ground-water flow analysis in the slope above Shum Wan Road, Hong Kong

2001 ◽  
Vol 7 (3) ◽  
pp. 239-250 ◽  
Author(s):  
S. Nandy ◽  
J. J. Jiao
Keyword(s):  
Ground Water ◽  
Water Level ◽  
Factor Of Safety ◽  
Ground Water Level ◽  
Water Model ◽  
Specific Yield ◽  
Clay Layer ◽  
Initial Water ◽  
Stability Analyses ◽  
Hydrogeological Study

Abstract On August 13, 1995, a slope above Shum Wan Road failed due to high rainfall and caused a 30-m section of Nam Long Shan Road to collapse. The slope consists of weathered tuffs with a clay layer on the surface of the failure. A hydrogeological study was carried out by saturated finite difference grid model, MODFLOW, for the slope at the Shum Wan Road area. From the ground-water model, it was found that the ground-water level reached three meters below the ground surface during failure. The model is sensitive to recharge and specific yield. The presence of the clay layer helped to maintain a high ground-water level. Stability analyses were performed using SLOPE/W. The result of stability analyses showed that the factor of safety, F, decreased due to the rising initial water table. On the 31st of July, the factor of safety was 1.41, and dropped down to 1.01 on the 3rd of August. The factor of safety again rose back to 1.31 on the 8th of August and it finally dropped down to 0.99 on the morning of the 13th of August. The present study showed that the antecedent rainfall had some influence on stability of the slope. The amount of water in the form of seepage, which drained out from the seepage surface from the lower part of the slope, is quantified and found to be 790 m 3 . Preventive measures can be taken by inserting horizontal pipes in the slope to drain out the ground water in the form of seepage or by covering the slope with shortcrete or chunam.

Elastic local buckling strength of I-beam cantilevers subjected to bending moment and shear force based on flange–web interaction

2021 ◽  
Vol 162 ◽  
pp. 107633
Author(s):  
Yoshihiro Kimura ◽  
Szymon M. Fujak ◽  
Atsushi Suzuki
Keyword(s):  
Shear Force ◽  
Local Buckling ◽  
Bending Moment ◽  
Buckling Strength

scholarly journals Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
High Strength ◽  
Element Model ◽  
Internal Force ◽  
Foundation Pit ◽  
Dimensional Finite Element ◽  
Influence Of Temperature On ◽  
Scale Experiment ◽  
Three Dimensional Finite Element

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

Imperialist Competitive Algorithm for Multiobjective Optimization of Ellipsoidal Head of Pressure Vessel

2011 ◽  
Vol 110-116 ◽  
pp. 3422-3428 ◽  
Author(s):  
Behzad Abdi ◽  
Hamid Mozafari ◽  
Ayob Amran ◽  
Roya Kohandel
Keyword(s):  
Genetic Algorithm ◽  
Pressure Vessel ◽  
Shear Force ◽  
Minimum Weight ◽  
Bending Moment ◽  
Imperialist Competitive Algorithm ◽  
Optimum Shape ◽  
Working Pressure ◽  
Competitive Algorithm ◽  
Bending Stresses

This work devoted to an ellipsoidal head of pressure vessel under internal pressure load. The analysis is aimed at finding an optimum weight of ellipsoidal head of pressure vessel due to maximum working pressure that ensures its full charge with stresses by using imperialist competitive algorithm and genetic algorithm. In head of pressure vessel the region of its joint with the cylindrical shell is loaded with shear force and bending moments. The load causes high bending stresses in the region of the joint. Therefore, imperialist competitive algorithm was used here to find the optimum shape of a head with minimum weight and maximum working pressure which the shear force and the bending moment moved toward zero. Two different size ellipsoidal head examples are selected and studied. The imperialist competitive algorithm results are compared with the genetic algorithm results.

Application of the Mode-Acceleration Technique to the Solution of the Moving Oscillator Problem

1999 ◽  
Author(s):  
Alexander V. Pesterev ◽  
Lawrence A. Bergman
Keyword(s):  
Shear Force ◽  
Series Representation ◽  
Bending Moment ◽  
Static Solution ◽  
Distributed Parameter ◽  
Distributed Parameter System ◽  
Parameter System ◽  
One Dimensional ◽  
Acceleration Technique ◽  
Moving Oscillator

Abstract The problem of calculating the dynamic response of a one-dimensional distributed parameter system excited by an oscillator traversing the system with an arbitrarily varying speed is investigated. An improved series representation for the solution is derived that takes into account the jump in the shear force at the point of the attachment of the oscillator, which makes it possible to efficiently calculate the distributed shear force and, where applicable, bending moment. The improvement is achieved through the introduction of the “quasi-static” solution, an approximation to the desired one, which makes it possible to apply to the moving oscillator problem the “mode-acceleration” technique conventionally used for acceleration of series in problems related to the steady-state vibration of distributed systems. Numerical results illustrating the efficiency of the method are presented.

The Influence of Rotatory Inertia and Transverse Shear on the Dynamic Plastic Behavior of Beams

1979 ◽  
Vol 46 (2) ◽  
pp. 303-310 ◽  
Author(s):  
Norman Jones ◽  
J. Gomes de Oliveira
Keyword(s):  
Transverse Shear ◽  
Shear Force ◽  
Yield Criterion ◽  
Yield Condition ◽  
Bending Moment ◽  
Plastic Behavior ◽  
Plastic Response ◽  
Rotatory Inertia ◽  
Perfectly Plastic ◽  
Theoretical Procedure

The theoretical procedure presented herein examines the influence of retaining the transverse shear force in the yield criterion and rotatory inertia on the dynamic plastic response of beams. Exact theoretical rigid perfectly plastic solutions are presented for a long beam impacted by a mass and a simply supported beam loaded impulsively. It transpires that rotatory inertia might play a small, but not negligible, role on the response of these beams. The results in the various figures indicate that the greatest departure from an analysis which neglects rotatory inertia but retains the influence of the bending moment and transverse shear force in the yield condition is approximately 11 percent for the particular range of parameters considered.

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