Model Test of the Impact of Active Ground Fissures on Metro Tunnel

2013 ◽  
Vol 405-408 ◽  
pp. 1334-1339
Author(s):  
Yi Yuan ◽  
Qiang Bing Huang ◽  
Jie Han ◽  
Ming Li Li
Keyword(s):  
Model Test ◽  
Hanging Wall ◽  
Foot Wall ◽  
Test Results ◽  
Soil Pressure ◽  
Ground Fissure ◽  
Ground Fissures ◽  
Tunnel Diameter ◽  
Metro Tunnel ◽  
The Impact

A model test was performed to investigate the impact of active ground fissure on metro tunnel. The test results show that under the action of active ground fissure, the metro tunnel behaviors as a cantilever elastic foundation beam, and the top is in tension and its bottom is in compression. The tensile parts are located in the foot-wall with the range 0.75～2.33D（D is tunnel diameter） distance from active ground fissure and the compressive parts are mainly located in the foot-wall with the range 3D distance from the fissure. When the settlement of hanging wall of ground fissure reaches 1cm（25cm in prototype）, the tunnel bottom appear cavity in the hanging wall and cracks in the foot-wall. With the settlement development of the hanging wall of active ground fissure the vertical soil pressure on the top of tunnel greatly increases and reduces at the bottom of tunnel in the hanging wall.

Model Test on Soil Stress and Displacement Changes Induced by Active Ground Fissure

2011 ◽  
Vol 250-253 ◽  
pp. 1266-1270
Author(s):  
Yue Liu ◽  
Qiang Bing Huang ◽  
Jian Bing Peng
Keyword(s):  
Model Test ◽  
Stress Reduction ◽  
Hanging Wall ◽  
Physical Model Test ◽  
Foot Wall ◽  
Reduction Zone ◽  
Ground Fissure ◽  
Stress Increase ◽  
Soil Stress ◽  
Stress Zone

With a large-scale physical model test of active ground fissure, the rules of the soil stress and displacement changes induced by active ground fissure are studied. The results show that, the active ground fissure causes soil stress and displacement field changes within a certain area, namely, soil stress reduce in the hanging wall, but increase in the foot wall. The farther from ground fissure the area is, the smaller the reduction and increase of soil stress caused by ground fissure movement. There are generally 4 soil stress distribution zones induced by active ground fissure, which are, original stress zone of the foot wall, stress increase zone, stress reduction zone and original stress zone of the hanging wall and among which, stress reduction zone is 1.0 to 1.5 times that of stress increase zone. The active ground fissure leads to abrupt displacement phenomena, taking the step shape at its both sides, and as the strata goes from deep to shallow, soil deformation area in section increases obviously. The influence area in the hanging wall is bigger than that in the foot wall.

scholarly journals Physical Modeling and Numerical Simulation of the Seismic Responses of Metro Tunnel near Active Ground Fissures

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Nina Liu ◽  
Quanzhong Lu ◽  
Jun Li ◽  
Jianbing Peng ◽  
Wen Fan ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Hanging Wall ◽  
Shaking Table ◽  
Burial Depth ◽  
Soil Pressure ◽  
Ground Acceleration ◽  
Ground Fissures ◽  
Railway Systems ◽  
Face Threats ◽  
Metro Tunnel

Ground fissures pose serious hazards to underground, as well as aboveground, structures. In underground railways, which are near ground fissures, the potential for disasters is even higher since tunnels face threats from fissure activities. To determine the interaction between a tunnel and ground fissure in the event of an earthquake, field surveys and data analysis were applied to study the activity and damage caused by the fissure. Shaking table tests and a numerical simulation model were used to understand the dynamic response of the fissure site and tunnel. The fissure site had a clear hanging wall effect, where the acceleration amplification was larger in the hanging wall than that in the footwall both on the surface and at the middle of the fissure site. The zone of influence was also wider in the hanging wall. The acceleration magnification factor increased with the burial depth and peak acceleration of the input earthquake. The peak ground acceleration (PGA) decreased with the burial depth on both sides of the fissure. The greatest PGA coefficient was obtained at the surface of the site. The vertical soil pressure was influenced by the metro tunnel and fissure. The vertical soil pressure was larger in the hanging wall, especially in the zone near the fissure, but was less near the tunnel. The horizontal soil pressure above the tunnel was less than that near the fissure. The results of this study are essential for the safe design of underground railway systems.

scholarly journals Activity Characteristics and Safety distance of Gaoliying Ground Fissure in Beijing

2019 ◽  
Vol 79 ◽  
pp. 02009
Author(s):  
Haigang Wang ◽  
Tongchun Qin ◽  
Haipeng Guo ◽  
Juyan Zhu ◽  
Yunlong Wang ◽  
...  
Keyword(s):  
Ground Water ◽  
Land Subsidence ◽  
Groundwater Level ◽  
Hanging Wall ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Rapid Decrease ◽  
Ground Fissure ◽  
Ground Fissures ◽  
Safety Distance

In all ground fissures in Beijing, Gaoliying Ground Fissure has characteristics of highly activity, and it cause serious damages on constructoins. With the distribution as well as the development of land subsidence and the change of the groundwater level, a series of work has been conducted to explain the mechanism of the formation of Gaoliying Ground Fissure. For example, field damage investigations and trench observations were used to define the affected distance of ground fissure; three-dimensional deformation was monitored to determine active characteristic of ground fissure. This paper points out that Gaoliying ground fissure is controlled by Huangzhuang-Gaoliying Fault, which mainly moves in the vertical direction. The rapid decrease of the ground water level greatly increases the development of ground fissure. The distance of damaged zones affected by ground fissure in the hanging-wall of the fault reaches 49.5m, and the distance of damaged zones in the footwall of the fault is 17.5 m. A suggested safety distance of type-one and type-two buildings is 100 m. For type-three buildings, the suggested safety distance is 80 m.

Study on Vertical Earth Pressure of Slab Culvert under High Embankment

2012 ◽  
Vol 256-259 ◽  
pp. 1898-1902 ◽  
Author(s):  
Bao Kuan Ning ◽  
He Fan ◽  
Lei Gong ◽  
Guo Qing Liu
Keyword(s):  
Numerical Simulation ◽  
Boundary Conditions ◽  
Field Test ◽  
Structural Design ◽  
Earth Pressure ◽  
Test Results ◽  
Soil Pressure ◽  
Vertical Earth Pressure ◽  
The Impact ◽  
Good Agreement

With the increasing of embankment culvert engineering applications, there has been due in part to the structural design is too conservative and not economic or select unreasonable structural form, leading to the phenomenon of cracking or even collapse of the culvert structure, and the phenomenon has seriously affected the normal use of the highway. In this paper, the numerical simulation of vertical earth pressure distribution on different structural forms of embankment on culverts, to discuss the impact of boundary conditions, fill height, the thickness of the culvert culverts vertical earth pressure. Combined with Heda highway a culvert covert field test results and numerical simulation results were compared and analyzed. The results show that the numerical simulation and field test results in good agreement with the culvert structure in the form of vertical earth pressure of the embankment culverts have a greater impact; the structure of different forms of the culvert in the upper soil pressure is significantly different. In addition, analysis of the impact of boundary conditions, filling height of culvert vertical earth pressure values. The results can reference for the study of the structural design of the embankment culverts security.

On the Distribution of Wave Impact Loads on Offshore Structures

2017 ◽  
Author(s):  
Thomas B. Johannessen ◽  
Øystein Lande ◽  
Øistein Hagen
Keyword(s):  
Model Test ◽  
Load Distribution ◽  
Impact Load ◽  
Peak Load ◽  
Offshore Structures ◽  
Impact Loads ◽  
Test Results ◽  
Wave Impact ◽  
The Impact ◽  
Crest Height

For offshore structures in harsh environments, horizontal wave impact loads should be taken into account in design. Shafts on GBS structures, and columns on semisubmersibles and TLPs are exposed to impact loads. Furthermore, if the crest height exceeds the available freeboard, the deck may also be exposed to wave impact loads. Horizontal loads due to waves impacting on the structure are difficult to quantify. The loads are highly intermittent, difficult to reproduce in model tests, have a very short duration and can be very large. It is difficult to calculate these loads accurately and the statistical challenges associated with estimating a value with a prescribed annual probability of occurrence are formidable. Although the accurate calculation of crest elevation in front of the structure is a significant challenge, industry has considerable experience in handling this problem and the analysis results are usually in good agreement with model test results. The present paper presents a statistical model for the distribution of horizontal slamming pressures conditional on the incident crest height upwave of the structure. The impact load distribution is found empirically from a large database of model test results where the wave impact load was measured simultaneously at a large number of panels together with the incident crest elevation. The model test was carried out on a circular surface piercing column using long simulations of longcrested, irregular waves with a variety of seastate parameters. By analyzing the physics of the process and using the measured crest elevation and the seastate parameters, the impact load distribution model is made seastate independent. The impact model separates the wave impact problem in three parts: – Given an incident crest in a specified seastate, calculate the probability of the crest giving a wave impact load above a threshold. – Given a wave impact event above a threshold, calculate the distribution of the resulting peak load. – Given a peak load, calculate the distribution of slamming pressures at one spatial location. The development of the statistical model is described and it is shown that the model is appropriate for fixed and floating structures and for wave impact with both columns and the deck box.

Physical Model Test for the Interaction on Circular Cross-Section Tunnel Crossing Ground Fissure with 60°

2011 ◽  
Vol 261-263 ◽  
pp. 933-937
Author(s):  
Kai Ling Li ◽  
Yang Liu ◽  
Yu Ming Men ◽  
Jing Ping Yan ◽  
Hong Jia Liu
Keyword(s):  
Physical Model ◽  
Cross Section ◽  
Model Test ◽  
Hanging Wall ◽  
Circular Cross Section ◽  
Structural Deformation ◽  
Physical Model Test ◽  
Tunnel Structure ◽  
Ground Fissure ◽  
Longitudinal Strains

Physical model test about the interaction between tunnel structure and soil under circler tunnel crossing the ground fissure belt with 60° was carried out, measuring the longitudinal strains of structure, the relative displacement at the bottom of the tunnel and the surrounding rock pressure. The test results show the deformation on the tunnel structure with circular cross-section is a composition of bending, shearing and twisting. The main deformation in first stage of settlement is bending, but the twisting deformation is more outstanding after the void appears at the bottom of the tunnel. Structural deformation in hanging wall is larger than that of the footwall, whereas structural stress in footwall is larger than that of the hanging wall. The segmentation of lining tunnel structure should be utilized to fit the distortion, bending and shearing in the metro tunnel aslant crossing the ground fissure belt. Twisting action should be considered in the structural design, and the tunnel structure in footwall should be strengthened by using high-performance concrete.

Risk Assessment on Ground Fissure Disasters of Xi’an Metro Line 3

2011 ◽  
Vol 255-260 ◽  
pp. 3841-3845
Author(s):  
Zhen Wei Jiang ◽  
Qi Yao Wang
Keyword(s):  
Risk Assessment ◽  
Numerical Analysis ◽  
Model Test ◽  
Evaluation Model ◽  
Geological Environment ◽  
Ground Fissure ◽  
Ground Fissures ◽  
Risk Degree ◽  
Sedimentation Value

Due to special geological environment in Xi’an, serious ground fissure disasters will occur to the Metro construction. According to the planning, Metro Line 3 will meet with the ground fissures at 15 segments. Based on the results of model test and numerical analysis, the minimum sedimentation value of ground fissure arousing disasters on metro was determined as . By using the evaluation model of risk degree as R = P×V, risk degrees of each segment where the metro crossed ground fissures was calculated. The results showed that in normal design circumstances, there are eight ultra-high risks segments and two high risks segments. Therefore, special measures should be taken to reduce risks for these segments with high risks or above.

Study on Interaction between Soil and U-Shaped Subway Tunnel in the Environment of Ground Fissures

2011 ◽  
Vol 250-253 ◽  
pp. 2342-2345 ◽  
Author(s):  
Yang Liu ◽  
Kai Ling Li ◽  
Yu Ming Men ◽  
Guang Yuan Weng ◽  
Hong Jia Liu
Keyword(s):  
Hanging Wall ◽  
Interaction Mechanism ◽  
Vertical Displacement ◽  
Soil Mass ◽  
Relative Displacement ◽  
Tunnel Structure ◽  
Subway Tunnel ◽  
Ground Fissure ◽  
Ground Fissures ◽  
Deformation Area

The interaction mechanism, between soil and U-shaped Subway tunnel, is studied by numerical simulation in the environment of ground fissures. The Subway Line 2 through the ground fissures in Xi’an. The analysis results show that the soil mass influenced by the relative displacement and the vertical displacement gradually increases with the relative displacement increasing of ground fissures movement. The deformation area of tunnel lies in the two sides of presupposed ground fissure, and the area enlarge with vertical relative displacement increasing. The tunnel structure damages at the ground fissures when the relative displacement reaches to 100mm. The footwall part is in tension and the hanging wall part is under pressure on the top of tunnel structure at the ground fissure. The footwall part is under pressure and the hanging wall part is in tension on the bottom of tunnel structure at the ground fissure. In the practical projects, the sectional type tunnel should be employed when the Subway tunnel through the ground fissures.

Shallow Water STL Mooring and Riser System

2009 ◽  
Author(s):  
Qinzheng Yang ◽  
Muthu Chezhian ◽  
Geir Olav Hovde
Keyword(s):  
Shallow Water ◽  
Wave Height ◽  
Model Test ◽  
Water Depth ◽  
Significant Wave Height ◽  
Mooring Line ◽  
Test Results ◽  
Sea State ◽  
Significant Wave ◽  
The Impact

A shallow water disconnectable STL turret mooring and riser system has been developed for water depth between 30 and 50 m. This technology is based on APL’s disconnectable STL (Submerged Turret Loading) and STP (Submerged Turret Production) technologies which had been widely applied for water depth between 70 m to 2600 m for FPSOs and LNG offshore terminals. The advantage of disconnectable system is that the mooring and riser system can be designed to a preferred sea state. When the sea state is higher than design sea state (like hurricane), the vessel can be disconnected and sail away. The shallow water STL system consists of STL buoy, mooring lines, riser system and landing pad. The interface with vessel is the same as traditional STL system. The mooring and riser system are connected to the vessel through STL buoy and can be pulled into vessel by using ship winch. Unlike traditional STP and STL buoys, the shallow STL buoy has a net weight and will stay on the landing pad when disconnected from vessel. The landing pad is designed to support the impact load from STL buoy and supply enough friction for the STL buoy to stay in position during 100-year storm. The mooring system design has taken the advantage of directionality of weather when close to the shore by using different mooring line length in different directions. Further an innovative Hold-Back-Wave riser configuration has been developed for shallow water system. The riser configuration has a larger flexibility compared to traditional wave configuration and has proved to be feasible for significant wave height at least 7 m when connected to the vessel and 10+ m when disconnected from the vessel. Model test for the disconnectable shallow water turret mooring and riser system had been performed in MARINTEK, Trondheim with a LNG re-gasification vessel model at 30 m water depth. For connected system, significant wave height Hs = 6 m and 8 m has been tested. The mooring and riser system perform well, as predicted. For disconnected system (when the buoy sitting on the landing pad), significant wave height Hs = 10 m has been tested. The STL buoy is sitting on the landing pad without significant movement and the riser system performs well. SIMO program has been used to calibrate the model test results with numerical simulations. By adjusting surge, sway, yaw damping and 2nd order wave drift force, the calibrated SIMO model agrees well with model test results and can be used for similar development.

Mechanical Analysis of Tunnel Crossing Ground Fissure

2011 ◽  
Vol 243-249 ◽  
pp. 3376-3380
Author(s):  
Kai Ling Li ◽  
Hong Jia Liu ◽  
Yang Liu
Keyword(s):  
Numerical Simulation ◽  
Frictional Force ◽  
Mechanical Characteristics ◽  
Mechanical Analysis ◽  
Evolution Process ◽  
Distribution Law ◽  
Ground Fissure ◽  
Ground Fissures ◽  
Interface Mechanics ◽  
Metro Tunnel

Ground fissures is one of typical geo-hazards in Xi’an area, which may cause damage of various types of buildings, city lifeline projects and resources, especially endangering the construction and running of Xi’an Subway. Ground fissures in Xi’an were introduced firstly, and models of land deformations and section destroy were found around Xi’an subway. Secondly, based on the interface mechanics, mechanical characteristics of interface between stratum on fissure and metro tunnel are studied, and void underneath metro tunnel are analyzed emphatically. At last, the result of numerical simulation shows that distribution law and amount of frictional force, scale and location of void under the tunnel, influence deformation and stress of tunnel; and then it also provides a theory basis for effective forecast evolution process of void underneath.

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