Back-fill Grout Experimental Test for Discharged Soils Reuse of the Large-diameter Size Slurry Shield Tunnel

Shunhua Zhou,Xue-Li Zhou,Chang Ji,Junhua Xiao 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.3

The construction of a slurry shield tunnel produces large amount of excavated soil. Direct discharge of the excavated soil by transportation not only increases the overall construction cost but also raises environmental concerns of pollution. In this study, we explore in-situ recycle of excavated soil in the Nanjing Yangtze River tunnel project as the back-fill grout. A series of laboratory were carried out to determine the synchronous grout parameters, including compression strength and shear strength, initial setting time, fluidity, consistency, and bleeding rate. The mixture ratio of the back-fill grout is also discussed to optimize the grout performance. It is found that: (1) the excavated soil produced from the construction of slurry shield tunnel in this project can be reused as the material of back-fill grout in the sand stratum; (2) Proper selection of binder/sand ratio and fly ash/cement ratio improves the performance of the synchronous grout. The test results demonstrated that the discharged soil can be recycled in-situ as the grouting material in the sand stratum.

한국어 쓰기 교육에서의 ‘마인드 맵’ 지도 방안 연구

조순화 ( Zhao Shunhua ) 중국한국(조선)어교육연구학회 2020 한국(조선)어교육연구 Vol.15 No.-

Writing using a mind map can be useful in the pre-writing process, especially in the content creation part of the pre-writing process, and when applied to the entire process of writing can help create creative content and is effective in selecting and configuring the material, it is easy to build an overview. It can also take into account the flow of the overall text, and consider statements related to the subject in terms of unity, consistency, and emphasis.

Wall Deflection and Ground Surface Settlement due to Excavation Width and Foundation Pit Classification

Hongju Xiao,Shunhua Zhou,Yuyong Sun 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.4

Foundation pits have obvious spatial effect, and the lateral wall deflection, ground movement and basal heave stability are closely related with the excavation width. A database of 92 case histories with extensive excavation widths in soft soil in China are collected and analyzed. The maximum lateral wall deflections and maximum ground surface settlements measured are smaller than the case histories there before. With the increase of excavation width, the maximum lateral wall deflections and the maximum ground surface settlements increase firstly and then tend to stable. The database indicates that the type of retaining structure has little relevance to the excavation width of the foundation pit. There are two types of basal heave according to the excavation width, single-peak and double-peak. Three types of foundation pit considering excavation width, named wide foundation pit, normal foundation pit and narrow foundation pit, are proposed based on the slip circle basal heave analysis approach. The classification method is consistent with the measured data and the simulated results.

Earth Pressure and Internal Forces of Tunnel Lining in Jet Grouting Reinforced Mud Stratum

Haibo Jiang,Shunhua Zhou,Honggui Di,Weitao Ye,Zhi Liu,Yu Zhao 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.10

In this study, field measurements of the earth pressures and the main reinforcement strains were carried out at three shield tunnel linings in mud stratum reinforced by vertical jet-grouted piles during tunnel construction and post-construction. The measured strains were used to back-calculate the linings' internal forces. The measured earth pressures and the back-calculated internal forces were compared to corresponding design values. The results indicate that the earth pressure and the internal forces increased rapidly, before exhibiting a fluctuating decrease and finally a long-term slow change, after lining assembly. The vertical jet-grouted piles were beneficial to mobilise the soil arching effect and led to the real earth pressure on the lining significantly smaller than the full overburden pressure, even with a relatively shallow buried depth. The vertical jet-grouted piles intensified the influence of backfill grouting on the earth pressure and caused the lining segments near the backfill grouting holes to continuously bear more radial pressure in the long-term. The resultant internal forces during lining assembly were large, and the Conventional Model failed to consider this element of the internal forces. The findings can provide a reference for the design and the construction of similar projects.

Differential settlement and soil dynamic stress of a culvert-embankment transition zone due to an adjacent shield tunnel construction

Yao Shan,Shunhua Zhou,Yao Shu 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.7

The effects of shield tunnel construction on the differential settlement and the distribution of soil dynamic stress of an adjacentculvert-embankment transition zone are investigated. A construction project of shield tunnels in Hangzhou (China) beneath anexisting railroad culvert-embankment transition zone is employed as a case study. Firstly, the shield tunneling activities in the vicinityof a culvert-embankment transition zone are simulated by a three-dimensional (3D) Finite Element Analysis (FEA) method. Thedifferential settlement of the transition zone is calculated to evaluate the influence of the shield tunneling on the safety of the passingtrain. Secondly, a plane strain model is employed to investigate the discipline of the soil dynamic stress in transition zones, which isinduced by the passing train and the shield tunnel beneath the railroad. Results indicate that the reinforcement treatment of thefoundation is required since the embankment differential settlement is significantly affected by the shield tunneling. Finally, arecommended treatment is introduced according to the property of the surrounding soil. Numerical simulation reveals that thistreatment is appropriate for reducing the differential settlement and soil dynamic stress of the transition zone.

Estimating Earth Pressure during Tunneling in Gravel-cobble Stratum by Considering Sensor-particle Size Effect

Longlong Fu,Shunhua Zhou,Yue-xiao Zheng,장리 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.6

When tunneling in gravel-cobble stratum with earth balanced shield, the ratio between the diameters of the pressure sensor embodied in muck chamber and cut gravels is generally small. The small sensor-particle size ratio leads to considerable difference between the measured and actual earth pressure. This makes the configuration of earth pressure a difficult task and furtherly affects tunneling efficiency and safety. This work characterizes the variation of stress measurement error in a granular packing with consideration of the sensor-particle size ratio, the particle size distribution as well as the contact force distribution. The probability density function of stress measurement error is built according to a general probability distribution of inter-particle contact force. After then, a probability-based regressive procedure is proposed to estimate the applied stress with the measured stress. For stress samples with a same target stress but different biases, the stress estimated by the probability-based procedure has a minor variation and thus is more reliable than the arithmetic mean stress. Finally, the probability-based procedure is adopted to estimate the actual earth pressure of a well-tunneled section in Chengdu gravel-cobble stratum, according to which the lateral pressure coefficient of Chengdu gravel-cobble stratum is suggested as 0.20 − 0.28.

Effect of Dynamic Interaction of Two Neighboring Tunnels on Vibrations from Underground Railways in the Saturated Soil

Chao He,Shunhua Zhou,Honggui Di,Xinwen Yang 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.11

This paper analytically investigates the dynamic interaction of two neighboring tunnels in the saturated soil. The twin tunnels are simulated using the Flügge shell theory, and the surrounding soil is modelled by the Biot's theory. The solution for cylindrical waves in saturated porous media is derived by applying the potential decomposition. The addition theorem is subsequently introduced to translate cylindrical waves, thereby satisfying the boundary conditions at the interfaces between the twin tunnels and saturated soil. Numerical examples are presented to analyze soil vibrations under different loading conditions calculated by different tunnel models. The neighboring tunnels have strong dynamic interaction, resulting in the insertion gain up to ± 20 dB. It is recommended to account for the interaction between neighboring tunnels when calculating the vibrations from underground railways.

Effect of lateral differential settlement of high-speed railway subgrade on dynamic response of vehicle-track coupling systems

Keping Zhang,Xiaohui Zhang,Shunhua Zhou 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.5

A difference in subgrade settlement between two rails of a track manifests as lateral differential subgrade settlement. This settlement causes unsteadiness in the motion of trains passing through the corresponding area. To illustrate the effect of lateral differential subgrade settlement on the dynamic response of a vehicle-track coupling system, a three-dimensional vehicletrack- subgrade coupling model was formulated by combining the vehicle-track dynamics theory and the finite element method. The wheel/rail force, car body acceleration, and derailment factor are chosen as evaluation indices of the system dynamic response. The effects of the amplitude and wavelength of lateral differential subgrade settlement as well as the driving speed of the vehicle are analyzed. The study reveals the following: The dynamic responses of the vehicle-track system generally increase linearly with the driving speed when the train passes through a lateral subgrade settlement area. The wheel/rail force acting on a rail with a large settlement exceeds that on a rail with a small settlement. The dynamic responses of the vehicle-track system increase with the amplitude of the lateral differential subgrade settlement. For a 250-km/h train speed, the proposed maximum amplitude for a lateral differential settlement with a wavelength of 20 m is 10 mm. The dynamic responses of the vehicle-track system decrease with an increase in the wavelength of the lateral differential subgrade settlement. To achieve a good operation quality of a train at a 250-km/h driving speed, the wavelength of a lateral differential subgrade settlement with an amplitude of 20 mm should not be less than 15 m. Monitoring lateral differential settlements should be given more emphasis in routine highspeed railway maintenance and repairs.

Seismic Analysis for Cross Transfer Subway Stations in Soft Soil Stratum

Yitao Li,Honggui Di,Shunhua Zhou,Quanmei Gong 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.5

This paper investigates the seismic properties of a cross transfer subway station under a horizontal earthquake wave in soft soil stratum. A 3-D simulation analysis model is established considering the dimensions and soil layers of a real structure. The HS-small model is employed to simulate the non-linear stiffness of soft soil. The dynamic responses of a single station case and a cross transfer station case are explored, followed by the direction of the input earthquake wave, the type of soil reinforcement in the overlapping area, had on the dynamic response were also analyzed. The simulation results show that the subway station has better seismic response than the single station, and soil reinforcement can increase the dynamic response of the different components in the overlapping area. As soil reinforcement stiffness increases, the dynamic response increases in both the upper and bottom stations at varying degrees. The findings from this paper provide a reference to the seismic design of cross transfer stations in similar ground.

Differential settlements in foundations under embankment load: Theoretical model and experimental verification

Wang, Changdan,Zhou, Shunhua,Wang, Binglong,Guo, Peijun,Su, Hui Techno-Press 2015 Geomechanics & engineering Vol.8 No.2

To research and analyze the differential settlements of foundations specifically, site investigations of existing railways and metro were firstly carried out. Then, the centrifugal test was used to observe differential settlements in different position between foundations on the basis of investigation. The theoretical model was established according to the stress diffusion method and Fourier method to establish an analytical solution of embankment differential settlement between different foundations. Finally, theoretical values and experimental values were analyzed comparatively. The research results show that both in horizontal and vertical directions, evident differential settlement exists in a limited area on both sides of the vertical interface between different foundations. The foundation with larger elastic modulus can transfer more additional stress and cause relatively less settlement. Differential settlement value decreases as the distance to vertical interface decreases. In the vertical direction of foundation, mass differential settlement also exists on both sides of the vertical interface and foundation with larger elastic modulus can transfer more additional stress. With the increase of relative modulus of different foundations, foundation with lower elastic modulus has larger settlement. Meanwhile, differential settlement is more obvious. The main error sources in theoretical and experimental values include: (a) different load form; (b) foundation characteristics differences; (c) modulus conversion; (d) effect of soil internal friction.