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Collaborating Authors
Investigation on the Settlement of Yangtze River Levee Caused by the Shield Tunneling: A Case Study in Sutong GIL
Xue, Y. (Geotechnical and Structural Research Center of Shandong University) | Li, X. (Geotechnical and Structural Research Center of Shandong University) | Kong, F. (Geotechnical and Structural Research Center of Shandong University) | Qiu, D. (Geotechnical and Structural Research Center of Shandong University) | Tan, X. (Shandong Provincial Lunan Geology and Exploration Institute) | Zhen, H. (Shandong Provincial Lunan Geology and Exploration Institute)
Abstract In order to evaluate the impacts of shield tunneling (referred the Sutong GIL project) on the stability of the levee and control its settlements, this study adopted the neural network and regression analysis to analyse settlement data of the levee derived from the numerical simulation. It can be concluded that the curves of the lateral settlement of the levee caused by the shield tunneling are approximately agreement with the Gaussian normal curve, and the settlements of the levee are mainly induced by the process of the shield tunneling and supporting. Additionally, the neural network model can be utilized to accurately predict the settlement of the levee and optimize the shield tuneling parameters to reduce the disturbance on the levee. Totally, the findings of this study can act as a reference for the levee settlement control in similar river-crossing tunneling projects. 1 Introduction With the development of the construction technology for super-large shield tunnel, shield tunneling has become one of the main construction methods for the river-crossing tunnels. Even though shield tunneling possesses the characteristics of fast construction speed and high security, but issues, such as the large levee settlement and the collapse of the levee, occur frequently when the tunnel along its route crossed the levee of a river. As the restrictions of construction conditions, the monitoring data of the levee settlement is generally not timely to predict of the levee settlement process. Therefore, it is worthy of the time to study the settlement regularity of levee aroused by the shield tunneling. Then, the construction scheme of the tunnel can be set up to reduce the disturbance of shield tunneling and to enable the stability of the levee. In general, academics and practitioners adopted Peck's formula (Peck et al. 1969) and its derivation formula (Fang et al. 1994) to predict the surface settlement of shield tunnel. However, these two formulas were not valid for the complex geological conditions as they could not reference the construction and geological parameters. Jiang et al. (2005) and Chakeri et al. (2013) established a numerical model to summarize the main factors of surface settlement during the shield tunneling. Based on the case of Xi'an subway, Zhu et al. (2016) proposed an assessment method of surface subsidence. According to the data analysis of examples, Ocak, I. & Seker, S.E. (2013) compared the prediction capabilities of the three prediction methods of land subsidence and presented an optimization method. Lee et al. (1992) presented a method to estimate the surface loss of the shield tunneling by interval parameters. On the basis of this research setting, Loganathan et al. (1998) derived an analytic solution of surface settlement in the shield tunneling construction and verified its applicability through five practical cases.
Summary The recent occurrence of floods in Northern and Central Italy as well as in the entire Europe caused important damages to agriculture, industry and infrastructures, to residential buildings and in some cases were also reported several casualties. Among these the November 2010 event, mostly occurred in the plain area of the Veneto Region (North-Eastern Italy), was particularly severe reaching a maximum rainfall intensity of more than 200 mm in 10 hours and causing the failure of 15 river embankments. The structure and the stratigraphy of earthen levees and of their geological basement represent a vital information and the eventuality of a collapse, also of minor embankments, frequently involves unaffordable social cost. The standard approach of monitoring the levees using sparse geotechnical tests and visual analysis is no longer satisfactory as the recent changes in the flood regime increased the stress on these structures and the associated risk of failures. An high resolution geophysical imaging procedure (namely EMAR), based on electromagnetic induction (FDEM) and multichannel radar (GPR), has been developed, tested and validated on a large scale survey of the embankments of a major river in North-eastern Italy. Using this procedure it was possible to investigate more than 100 km of embankments in 5 working days showing great potentials to cost-effectively monitoring earthen levees.
- Geology > Geological Subdiscipline > Stratigraphy (0.54)
- Geology > Rock Type (0.35)
- Geophysics > Seismic Surveying (1.00)
- Geophysics > Electromagnetic Surveying (0.70)
This study is to evaluate the safety of a sea levee under earthquake condition. The evaluation is performed by both theoretical analysis and numerical simulation, besides a case in field is adopted to verified the analysis and simulation. Since a sea levee is subjected a combined forces and stresses, such as, wave force, earth pressure, self-weight, pore water pressure, and forces induced form earthquake, the theoretical analysis may obtain a closed-form solution, however, the complicated field condition may not be included in the analysis. A software with finite element method is used to simulate the complicated conditions. The revetment of a sea levee which found on a thick deposit with saturated loose sand may collapse or slide soil liquefaction as deposit subjected by earthquake force. The results also revealed that the hazards caused by a earthquake are not damage of the levee itself. Instead, the flood due to the collapse of the levee structure may induce the major disasters. INTRODUCTION Since 1999 Chi-Chi Earthquake took place at the middle of Taiwan, the accompanied shallow seismic motions exerted a great impact on the riverbanks, sea levees, reservoirs, dams, weir, watercourses as well as farmland facilities and induced lots of serious damages. The failure modes include cracking, distortion, sliding, collapse, heaving, avalanche and especially the soil liquefaction. It was found that approximately 220m in accumulation of sea levees were damaged during this seismic excitation at the seafront of Chang-Hua County. Among those sea levees, some were damaged in collapse due to soil liquefaction, such as Han-Pao sea levee, Chang-Hua levee way, Chao- Yang-Cuo sea levee, Siasi-Chian sea levee, Shan-Keng sea levee and Siahai-Chian sea levee. It is revealed from the above field cases that the destructive power of the unexpected seismic loading was more intensive than the induced wave forces exerting on the rigid-type sea levee structures.
Summary The Great Miami River System in southwestern Ohio has one of the oldest flood control systems in the country. In an attempt to gauge the effectiveness of the levee system during flood times, electrical resistivity has recently been used to map the internal structure of the levee to delineate sand and gravel pockets, which may be prone to wash outs during a major flood. To do this, 2D continuous resistivity profiles were collected at two levee sites in the greater Dayton area. Sand and gravel lenses tend to appear as high resistivity anomalies within the levee structure. Future goals include drilling boreholes at high resistivity anomaly locations to test the accuracy of electrical resistivity to determine sand and gravel lenses.
- North America > United States > Ohio (0.38)
- North America > United States > Gulf of Mexico > Eastern GOM (0.28)
Interrogating Levees Using Seismic Methods In Southern Texas
Ivanov, Julian (The University of Kansas) | Miller, Richard D. (The University of Kansas) | Ballard, Robert F. (US Army Engineer Research and Development Center) | Dunbar, Joseph B. (US Army Engineer Research and Development Center) | Stefanov, James (U. S. Section of International Boundary and Water Commission)
ABSTRACT The primary objective of this work was to determine compressional and shear velocity distribution within the body of five levees and any relationship to existing core and airborne EM data. Several different types of seismic data were recorded at each of the five different levee sites, each site possessing unique core and/or EM characteristics. Several seismic data analysis techniques were appraised including, P- and S-wave refraction, P- and S-wave refraction tomography, Rayleigh and Love-wave surface-wave analysis using multi-channel analysis of surface waves (MASW), and P- and S-wave cross-levee tomography. While the P-wave methods provided reasonable results, the S-wave methods produced surprising Vs properties. The reason for the latter effect is not clear; possibly the result of mode conversion, which is likely at sites with Poisson's ratio greater than 0.438. Alternatively, these could be real and related to mechanical compaction and material distribution within the levees.
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.69)