Abstract
In order to study the instability mode of shield excavation face in soil-rock composite stratum and determine the ultimate support pressure of excavation face, this paper selects two typical soil-rock composite strata and uses three-dimensional finite element software to study the failure development process of shield excavation face. Based on the principle of limit equilibrium, a calculation model of limit support pressure for soil-rock composite stratum is proposed and applied to practical engineering. It is found that the shape of “unloading loosening zone” is mainly determined by the properties of upper soil and the properties of lower rock mainly determine the scope and shape of “sliding instability zone.” With the increase of soil proportion coefficient, the ultimate bearing capacity increases nonlinearly and the growth rate decreases gradually. At the same time, the influence of overlying Earth pressure and soil cohesion cannot be ignored.
Highlights
In the construction of urban rail transit, the instability of stratum disturbance and the complexity and sensitivity of surrounding environment are the objective reality faced by builders
Complicated, the difficulty of controlling the support pressure of the excavation surface is greatly increased compared with that of a homogeneous layer, and the rock and soil are prone to instability and damage due to insufficient support of the excavation surface, which has a great impact on the project [1,2,3,4,5]. erefore, it is of great significance to deeply study the deformation and failure mechanism of the excavation face caused by the shield tunneling in the soil-rock composite stratum and to explore the ultimate support pressure of the shield tunneling in the soil-rock composite stratum
The numerical simulation shows that when shield tunneling in soil-rock composite stratum, the instability mode of the excavation face is directly related to geological conditions due to insufficient support pressure
Summary
In the construction of urban rail transit, the instability of stratum disturbance and the complexity and sensitivity of surrounding environment are the objective reality faced by builders. Based on the shield construction experience and previous research results and combined with the existing shield construction conditions, this paper selects two typical soilrock composite strata and uses the three-dimensional finite element numerical simulation program to systematically study the development process of instability and failure of shield excavation face in soil-rock composite strata and the relationship between excavation face support force and displacement. Based on the numerical simulation results, the analytical model of ultimate support pressure of shield excavation face in soil-rock composite stratum is deduced, and the Terzaghi loose Earth pressure formula is improved to be applied to the calculation model of wedge in soil-rock composite stratum. Based on the R3 line of Jinan metro, the paper makes an example analysis and analyzes the sensitivity of several main parameters affecting the ultimate support force of shield excavation face, so as to further understand the calculation model method of soilrock composite stratum wedge. Relevant conclusions can provide theoretical support for rapid and safe shield tunneling in soil-rock composite stratum
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
