Modeling the relationship between ground surface settlements induced by shield tunneling and the operational and geological parameters based on the hybrid PCA/ANFIS method

Tunneling in urban areas is growing in response to the increased needs for efficient transportation. Many urban tunnels are constructed in soft ground at shallow depths. Metro tunnels are usually constructed as twin-parallel tunnels and their adjacent constructions may lead to surface deformation, affecting the surface environment and the safety of the tunnels. Shield tunnelling is a commonly used as construction technique because it is very effective in reducing ground deformations and thus damage to urban infrastructure. The paper presents a 3D simulation of shield tunneling machines via the finite element code Abaqus and analysis model of ground surface settlements induced by a construction of twin-parallel tunnels. The results show that ground surface settlements induced by a construction of the left tunnel causes surface settlements of about 22÷24 mm and after the construction of both tunnels, it will cause ground subsidence has the greatest value of 33÷35 mm.

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Study of the influence of face pressure on surface settlements by shield tunneling

Journal of Mining and Earth Sciences ◽

10.46326/jmes.2020.61(1).04 ◽

2020 ◽

Vol 61 (1) ◽

pp. 31-40

Author(s):

Do Ngoc Thai ◽

Do Duc Toan ◽

Keyword(s):

Urban Areas ◽

Ground Surface ◽

Tunnel Boring Machine ◽

Shield Tunnel ◽

Shield Tunneling ◽

Tunnel Boring Machines ◽

Tunnel Boring ◽

The Face ◽

Boring Machines ◽

Surface Settlements

In the mechanized excavation of subway tunnels, the shield tunnel boring machine (TBM) has been developed in recent decades for managing the instability of the excavation profile in complicated geotechnical conditions in urban areas. The paper presents a 3D simulation procedure for the detailed description of TBM (via the finite element code Abaqus) and quantifies the influence of TBM face pressure on ground surface settlements. The model is used to calculate ground surface settlements for different values of TBM face pressure. An additional aspect of the investigation is the determination of the critical value of TBM face pressure, which controls face instability in very weak ground. During the advancement of shield tunnel boring machines, the face-stabilizing pressure is one of the most important factors of critical. In tunneling by shield tunnel boring machines, high face pressure often leads to surface upheaval, whereas low face pressure leads to sudden collapse of the face and ultimately settlement of the surface. For the model condition, the maximum value was quantity 250 kPa and the minimum value obtained quantity 150 KPa.

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Modeling the Temperature Field in the Ground with an Installed Slinky-Coil Heat Exchanger

Energies ◽

10.3390/en14134010 ◽

2021 ◽

Vol 14 (13) ◽

pp. 4010

Author(s):

Monika Gwadera ◽

Krzysztof Kupiec

Keyword(s):

Temperature Field ◽

Heat Exchanger ◽

Surface Temperature ◽

Ground Surface ◽

Heat Sources ◽

Ground Surface Temperature ◽

Coil Heat Exchanger ◽

The Relationship ◽

Temperature Responses ◽

Coil Heat

In order to find the temperature field in the ground with a heat exchanger, it is necessary to determine temperature responses of the ground caused by heat sources and the influence of the environment. To determine the latter, a new model of heat transfer in the ground under natural conditions was developed. The heat flux of the evaporation of moisture from the ground was described by the relationship taking into account the annual amount of rainfall. The analytical solution for the equations of this model is presented. Under the conditions for which the calculations were performed, the following data were obtained: the average ground surface temperature Tsm = 10.67 °C, the ground surface temperature amplitude As = 13.88 K, and the phase angle Ps = 0.202 rad. This method makes it possible to easily determine the undisturbed ground temperature at any depth and at any time. This solution was used to find the temperature field in the ground with an installed slinky-coil heat exchanger that consisted of 63 coils. The results of calculations according to the presented model were compared with the results of measurements from the literature. The 3D model for the ground with an installed heat exchanger enables the analysis of the influence of miscellaneous parameters of the process of extracting or supplying heat from/to the ground on its temperature field.

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LABORATORY FOOTING TEST ON PARTIALLY SATURATED SANDY SOIL

Jurnal Teknologi ◽

10.11113/jt.v78.8576 ◽

2016 ◽

Vol 78 (5-5) ◽

Author(s):

J. D. Nyuin ◽

M. J. Md Noor ◽

Y. Ashaari ◽

C. Petrus ◽

A. Albar

Keyword(s):

Sandy Soil ◽

Ground Surface ◽

Matric Suction ◽

Shallow Foundation ◽

Analysis And Design ◽

Test Tank ◽

Partially Saturated ◽

Saturated Condition ◽

Conventional Analysis ◽

The Relationship

Conventional analysis and design of shallow foundation are based on the assumption that the soil is under fully saturated condition. However, shallow foundations are typically constructed near the ground surface where the soil is under partially saturated condition. Therefore, more research to investigate the behaviour of shallow foundation in unsaturated soil is very essential in order to aid engineers in making good analysis and design. This paper presents a series of laboratory footing tests conducted on unsaturated sandy soil. A specially designed test tank was fabricated for the test. Square footings of two different sizes (100 mm x 100 mm and 150 mm x150 mm) were used and loaded on Rawang sand which has residual suction value of 10 kPa. The measured values of matric suction of the soil in the test tank were in the range of 0 to 30 kPa. Based on the results, it was observed that bearing capacities of shallow foundation under fully saturated condition were the lowest compared to soil under unsaturated conditions. The highest values were measured at matric suction equals to residual suction (i.e 10 kPa). Furthermore, the relationship between the bearing capacities of shallow foundation with the matric suction was observed to be non-linear.

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Experimental Research on the Relationship between Surface Polishing and Fracture Strength for Ground Ceramics

Materials Science Forum ◽

10.4028/www.scientific.net/msf.770.433 ◽

2013 ◽

Vol 770 ◽

pp. 433-436

Author(s):

Xin Li Tian ◽

Jian Quan Wang ◽

Bao Guo Zhang ◽

Peng Xiao Wang

Keyword(s):

Residual Stress ◽

Fracture Strength ◽

Ground Surface ◽

Residual Tensile Stress ◽

Residual Stress Field ◽

Polishing Process ◽

Machined Surface ◽

X Ray ◽

Surface Polishing ◽

The Relationship

Fracture strength is one of the key mechanics performances for engineering ceramics products, greatly influenced by the microscopic topography and residual stress field of ground surface. In this work, several testing equipments, such as the metallurgical microscope, surface profiler and X ray residual stress tester were introduced to investigate the relationships between microscopic topography, surface roughness, residual stress and fracture strength of ground ceramics, after the surface grinding and mechanical polishing. The experimental results show that a smoother machined surface with low roughness and residual stress is obtained through polishing with absolute alcohol for 20 minutes; the fracture strength of Si3N4SiC and Al2O3 are increased by 6.64%8.18% and 6.58% respectively, comparing to the ceramics without polishing; the surface stress concentration and residual tensile stress of polished ceramics are both reduced after an appropriate time of polishing process, which causes a certain improvement of ground fracture strength.

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The Effects of Landscape Elements on the Breeding Sites of Bloodsucking Midge

Sustainability ◽

10.3390/su13052863 ◽

2021 ◽

Vol 13 (5) ◽

pp. 2863

Author(s):

Kaowen Grace Chang ◽

Hungju Chien

Keyword(s):

Ground Surface ◽

Preventive Strategies ◽

Careful Selection ◽

Public Concern ◽

Breeding Sites ◽

Algae Growth ◽

Potential Habitats ◽

Landscape Factors ◽

The Relationship ◽

Selection Of

Forcipomyia taiwana, a bloodsucking midge that is one of the most irritating biting pests in Taiwan, has raised widespread public concern. However, we have little information about the extent to which landscape factors affect their potential habitats. As a result, landscape professionals do not have enough information to implement preventive strategies to control midges. The purpose of this study is to investigate the relationship between landscaping and algae growth for larval breeding sites of Forcipomyia taiwana. The intent is to determine the environmental strategies that make the planned landscape unsuitable for midges to breed. GIS based on data collected from 16 constructed landscape sites (317,187 m2 in total) was utilized to spatially examine the relationship between the occurrence of the algae for midge breeding sites and the ground surface types and planting characteristics in each landscape. The results revealed that the potential midge habitats can be controlled through careful selection of the ground surface, the improvement of the site drainage, and choosing plants with the appropriate characteristics. Apart from choosing the appropriate type of paving surface, the integrity of the paving installation and the coverage of the ecological surface also influence prevention efficacy.

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