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Li P.-F.,Economic and Planning Research Institute of Ministry of Railways | Li P.-F.,Tsinghua University | Li P.-F.,Beijing Jiaotong University | Zhang D.-L.,Beijing Jiaotong University | Zhao Y.,Economic and Planning Research Institute of Ministry of Railways
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2013

Aimed at the problem of subsea tunnel face stability, four analytical models including limit analysis upper bound method, wedge analysis, two-dimensional logarithmic spiral model and slice method for estimating the support pressure required for the face stability were summarized. With considering the pressure of overlying strata, theoretical analytical formulas were modified. Combined with the results of a practical example, the results of the numerical simulation and the analytical formulas were compared and analyzed. The results show that four analytical models were all on the safe side; and the limit analysis upper bound method model has the highest accuracy, followed by wedge analysis model, two-dimensional logarithmic spiral model and slice method. Source


Li P.,Economic and Planning Research Institute of Ministry of Railways | Li P.,Beijing Jiaotong University | Li P.,Tsinghua University | Zhao Y.,Economic and Planning Research Institute of Ministry of Railways | And 2 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2013

The action mode and space-time evolution laws of surrounding rock pressure are the core contents of tunnel supporting structure design, which are hot issues in underground engineering research. Based on the summary of main types and influencing factors of tunnel surrounding rock pressure and the statistical analysis of surrounding rock pressure of 91 monitoring sections in 44 tunnels, the population distribution characteristics of surrounding rock pressure and their relationships with surrounding rock grade and buried depth of tunnel are studied. Then the variation law of rock pressure and lateral pressure coefficient with the increase in buried depth is discussed. Based on the statistical analysis of field monitoring data of rock pressure, the basic law of rock pressure time-history is studied. Three stages including rapid growth-slowly growth-settle out is put forward; and the rapid growth stage is mostly the time during unsupported or without effect of support after tunnel excavation. Finally, the distribution laws of rock pressure along the tunnel and the feature of nonuniformity coefficient are discussed. The results offer some references for analyzing the pressure mechanism of tunnel surrounding rock and perfecting the design method of supporting structure. Source


Li P.,Beijing Jiaotong University | Li P.,Economic and Planning Research Institute of Ministry of Railways | Li P.,Tsinghua University | Zhang D.,Beijing Jiaotong University | And 3 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

Different from land tunnels, the subsea tunnels are located deeply under the sea, so the groundwater treatment is the key issue during tunnel construction. Simultaneously, water inflow control and calculation of water load acting on lining structure are the core issues. The external water pressure on lining will be reduced remarkably with low discharge by adopting the design discipline of blocking groundwater and limiting discharge. So the design of lining structure in subsea tunnels is more economical. Based on the correlation theory of groundwater hydraulics, a calculation methods of water load acting on composite lining and water inflow in subsea tunnels is derived. Taking Xiang'an subsea tunnel in Xiamen for example, the influences of variable parameters of primary support, secondary support and grouting circle on water inflow and external water pressure are then expounded by using theoretical analysis and numerical simulation. Subsequently, the program and method for choosing economic and rational parameters of grouting circle are put forward; and the reasonable parameters of grouting circle for Xiang'an subsea tunnel through the weathered deep slot F4are given, which gets satisfying effects. The results provide references for tunnel waterproofing and drainage system design in high water pressure and water-enriched regions including subsea regions. Source

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