Research on Shallow Buried and Large-Span Tunnelling Undercrossing a Highway

2011 ◽  
Vol 90-93 ◽  
pp. 1748-1756
Author(s):  
Chun Yang Liu ◽  
Jian Li ◽  
Zhong Sheng Tan
Keyword(s):  
Ground Settlement ◽  
Safety Requirement ◽  
Large Span ◽  
Tunnel Section ◽  
Monitoring Result ◽  
Soil Settlement ◽  
Security And Reliability ◽  
Core Soil ◽  
Primary Support ◽  
Excavation Area

WenXiang tunnel ,one of the tunnels constructed for the ZhengXi Special passenger Railway in china. In this project we have carried out a series of research on optimizing the construction method for shallow and large-span tunnels in loess condition. According to the field monitoring of ground settlement, vault settlement and primary support stress of the tunnel section before tunnelling underneath the LianHuo Highway, the result indicates that soil settlement and primary support stress can not be controlled very well, and current construction program needs to be reformed since it can not meet construction safety requirement. Our synthetical analysis comprises the optimized methods have been used in construction, such as reducing excavation area, increasing excavation steps of pilot tunnel, reserving core soil, closing invert punctually, reinforcing primary support, etc. The security and reliability also has been verified by numerial analysis sofeware FLAC3D. From feedback of field implement and monitoring result, the effect of optimized method is significant; and all of these methods ensured this tough project implemented successfully. These results derived from our research are subject to a ceritain value that could be referred for future analogous project , in terms of controlling soil settlement and protecting surrouding building facilities.

scholarly journals Application of 3D Laser Scanning in Underground Station Cavity Clusters

2021 ◽  
Vol 2021 ◽  
pp. 1-12 ◽  
Author(s):  
Li Pinpin ◽  
Qiu Wenge ◽  
Cheng Yunjian ◽  
Lu Feng
Keyword(s):  
Laser Scanning ◽  
Incidence Angle ◽  
Measurement Data ◽  
Sectional Area ◽  
3D Laser Scanning ◽  
Validity And Reliability ◽  
Total Station ◽  
Tunnel Section ◽  
Underground Station ◽  
Primary Support

Given the shortcomings of the tunnel overbreak and underbreak control and primary support sectional area detection such as the single means, large workload, low efficiency, and poor accuracy, the use of three-dimensional laser technology can solve the above problems. Based on the Badaling Tunnel Great Wall underground station of the Beijing-Zhangjiakou Railway, the 3D laser scanning technology is used to analyze the distribution of the tunnel overbreak and underbreak and the sectional area of the primary support, compared with the total station measurement results. The results showed that the layout of the scanning measurement station should consider the requirements of scanning accuracy, control the station length and scanning incidence angle, and minimize the scanning station length to reduce the scanning error. The majority of the tunnel section was in overbreak, with the overbreak area ranging from 6.22  m 2 to 13.17  m 2 and the overbreak rate ranging from 0.283 to 0.598, and the area of underbreak was relatively small; no overexceeded headroom was found in the primary support, and the tunnel vault was not overbreak. The primary support clearance value of the vault is 0∼15  mm , the clearance value of the sidewall is 35  mm ∼40  mm , and the sidewall needs to be secondary shotcrete. The difference value between the 3D laser scanning measurement data and the total station measurement data is within 3  mm , which is within the error range, indicating the validity and reliability of the 3D laser measurement result.

scholarly journals Experimental Study and Estimation of Groundwater Fluctuation and Ground Settlement due to Dewatering in a Coastal Shallow Confined Aquifer

2019 ◽  
Vol 7 (3) ◽  
pp. 58 ◽  
Author(s):  
Jiong Li ◽  
Mingguang Li ◽  
Lulu Zhang ◽  
Hui Chen ◽  
Xiaohe Xia ◽  
...  
Keyword(s):  
High Speed ◽  
Prediction Method ◽  
Burial Depth ◽  
Confined Aquifer ◽  
Test Results ◽  
Well Test ◽  
Ground Settlement ◽  
Empirical Prediction ◽  
Soil Settlement ◽  
Groundwater Fluctuations

The coastal micro-confined aquifer (MCA) in Shanghai is characterized by shallow burial depth, high artesian head, and discontinuous distribution. It has a significant influence on underground space development, especially where the MCA is directly connected with deep confined aquifers. In this paper, a series of pumping well tests were conducted in the MCA located in such area to investigate the dewatering-induced groundwater fluctuations and stratum deformation. In addition, a numerical method is proposed for the estimation of hydraulic parameter, and an empirical prediction method is developed for dewatering-induced ground settlement. Test results show that groundwater drawdowns and soil settlement can be observed not only in MCA but also in the aquifers underneath it. This indicates that there is a close hydraulic connection among each aquifer. Moreover, the distributions and development of soil settlement at various depths are parallel to those of groundwater drawdowns in most areas of the test site except the vicinity of pumping wells, where collapse-induced subsidence due to high-speed flow may occur. Furthermore, the largest deformation usually occurs at the top of the pumping aquifer instead of the ground surface, because the top layer is expanded due to the stress arch formed in it. Finally, the proposed methods are validated to be feasible according to the pumping well test results and can be employed to investigate the responses of groundwater fluctuations and stratum deformations due to dewatering in MCA.

Analysis of the ground settlement control of a large span metro station in Dalian city using the Centre Drift Method

2014 ◽  
Vol 18 (9) ◽  
pp. 1042-1069
Author(s):  
Xin-Bo Ji ◽  
Wen Zhao ◽  
Shen-Gang Li ◽  
Yong-Wei Zhou ◽  
Yong-Ping Guan
Keyword(s):  
Ground Settlement ◽  
Metro Station ◽  
Large Span ◽  
Dalian City

The Dynamic Construction Numerical Analysis of Large-Span Section, Long and Deep-Depth Tunnel

2012 ◽  
Vol 256-259 ◽  
pp. 1253-1257
Author(s):  
Hui Ming Bao ◽  
Xin Xiong
Keyword(s):  
Simulation Analysis ◽  
Scientific Basis ◽  
Analysis Model ◽  
Large Span ◽  
Initial Stress Field ◽  
The Core ◽  
Core Soil ◽  
Deep Depth ◽  
Simulated Analysis ◽  
Soil Excavation

Using finite element principle, the numerical simulation analysis model of the tunnels with large-span, long and deep-depth was established. The killed cells excavated in part as, while supporting part as a unit was reactivated among the simulation analysis. The changing characteristics of the initial stress field, the circular soil excavation and supporting, the core soil excavation, as well as the down step excavation and supporting was simulated analysis during dynamic construction of the tunnel. Those will be provided a scientific basis for the safe construction.

scholarly journals Study on ground settlement and structural deformation for large span subway station using a new pre-supporting system

2019 ◽  
Vol 6 (2) ◽  
pp. 181035 ◽  
Author(s):  
Pengjiao Jia ◽  
Wen Zhao ◽  
Xi Du ◽  
Yang Chen ◽  
Chaozhe Zhang ◽  
...  
Keyword(s):  
Steel Tube ◽  
Structural Deformation ◽  
Subway Station ◽  
Ground Settlement ◽  
Soft Soils ◽  
Supporting System ◽  
Steel Pipes ◽  
Large Span ◽  
First Time ◽  
Surrounding Soil

This study presents a novel construction pre-supporting system for large underground space excavation with shallow depth, Steel Tube Slab system (STS), in which adjacent steel pipes are connected by a couple of flanges, bolts and concrete for flexural capacity and lateral stiffness of the whole structure. The STS method is employed for the first time for the construction of the ultra-shallow buried and large span subway station in China, during which ground settlement and structural deformation are monitored. A numerical model for the subway station is established with reliability verified by monitored data comparison from numerical results and investigation on the effect of large span underground excavation on surrounding soil surrounding soil and existing buildings in soft soils. Unlike traditional methods, the STS method can effectively control and reduce the ground settlement during construction, thereby rendering it ideally suited for application in soft soils.

scholarly journals Dynamic Optimization Research on the Section Morphology of Large-span Tunnels in Shallow Rock Mass

2015 ◽  
Vol 9 (1) ◽  
pp. 210-213 ◽  
Author(s):  
Wang Hui ◽  
Wang Qing-biao
Keyword(s):  
Optimization Design ◽  
Ground Surface ◽  
Calculation Model ◽  
Dynamic Calculation ◽  
Optimization Analysis ◽  
Large Span ◽  
Ground Surface Settlement ◽  
Set Up ◽  
Engineering Stability ◽  
Excavation Area

The optimization design of the section morphology of large-span tunnels plays an important role for saving cost and improving the engineering stability. The flat ratio of tunnel which is as an important control index, its rationality is the key problem in the design of tunnels. Program with Python to set up the dynamic calculation model of a large-span tunnel planned to be constructed which can be run and analyzed in ABAQUS. The MATLAB language is used to compile the optimization analysis program based on genetic algorithm, and then the dynamic calculation model is embedded into it. Using excavation area, plastic zone, ground surface settlement, vault subsidence, etc. as optimal objective to make dynamic analysis for the model and put forward the reasonable flat ratio of the supported project. The result of this paper provides reference for the section optimization design of similar tunnel engineering.

scholarly journals Model Test Study on the Antibreaking Technology of Reducing Dislocation Layer for Subway Interval Tunnel of the Stick-Slip Fracture

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Guang-yao Cui ◽  
Xue-lai Wang
Keyword(s):  
Model Test ◽  
Active Fault ◽  
Fault Zones ◽  
Tunnel Engineering ◽  
Stick Slip ◽  
Test Study ◽  
Tunnel Section ◽  
Secondary Lining ◽  
Dislocation Layer ◽  
Primary Support

Based on the background of the Line F2-3 interval tunnel section of Jiujiawan in Urumqi Subway Line 1, this paper carries out the model test research on the antibreaking technology of the reducing dislocation layer in the tunnel section of the stick-slip fracture. The antibreaking effect of different locations and number of reducing dislocation layers in tunnel engineering is analyzed in this paper. The results show that when the double reducing dislocation layer, respectively, set between the surrounding rock and the primary support, and the primary support and the secondary lining, the antibreaking effect is the best. It is recommended to use this scheme for antibreaking design. The research results can provide reference for antibreaking design of traffic tunnels in active fault zones.

Numerical Analysis of Reserving Core Soil with Annular Excavation Method Used in Loess Tunnel

2014 ◽  
Vol 1065-1069 ◽  
pp. 143-146
Author(s):  
Zhi Jie Sun ◽  
Zhong Ming Su
Keyword(s):  
Working Condition ◽  
Bending Moment ◽  
Surrounding Rock ◽  
Maximum Pressure ◽  
3D Numerical Simulation ◽  
Construction Methods ◽  
Core Soil ◽  
Secondary Lining ◽  
Pressure Stress ◽  
Primary Support

To research the deformation regularity of loess tunnel in reserving core soil with annular excavation method compared with other construction methods, 3D Numerical Simulation is applied and the loess tunnel of highway is taken as an example. The research results show that[1]：The deformation of surrounding rock affected by the area of core soil is small.The stress regularity of different support structure influence on the area of core soil is different. This is mainly reflected that the maximum pressure stress of primary support increases with the area of core soil’s increasing, but the minimum bending moment of secondary lining is not appeared in the working condition which the minimum core soil area is.

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