Deformation Law And Support Scheme Optimization Of Consequent And Anti-dip Slopes Of High Inclination Angle Layered Rock Foundation Pits

With the rapid development of Chinese economy and the vigorous construction of urban infrastructure,a large number of deep excavation projects in layered rock masses have emerged.The deformation law and stability of slopes in layered rock foundation pits are mainly controlled by unfavorable geological factors such as rock structural planes and weak rock layers,and consequent slope and anti-dip slopes usually exhibit different deformation characteristics.However,the current theories and specifications for foundation pit support design are mainly based on a large amount of theoretical research and engineering practice experience summary of soil foundation pits.There are still certain shortcomings in the applicability of rock foundation pit engineering,leading to a lack of reliable and comprehensive theoretical basis for slope support design and optimization of rock foundation pits.In view of this,this article relies on the rock deep foundation pit project of the South Third Ring Subway Station of Xuzhou Metro Line 3.We mainly using numerical analysis and on-site measurement methods to carry out research on the deformation laws and support scheme optimization of consequent and anti-dip slopes of high inclination angle layered rock foundation pits,in order to provide guidance or reference for similar deep foundation pit rock slope support design.First of all,the deformation law and stability of high dip layered rock foundation pit along dip and anti-dip slopes are studied.Based on the foundation pit of the South Third Ring Station of Xuzhou Metro Line 3,a plane strain numerical model of layered rock foundation pit was established for the deepest section of the foundation pit.The unsupported excavation conditions were simulated,and the influence of factors such as structural plane cohesion,internal friction angle,and inclination angle of a single lithology rock layer on the deformation law and stability of inclined and anti-inclined slopes was studied.The most dangerous parameter combination of a single lithology layered rock foundation pit was obtained;On this basis,the influence of factors such as cohesion,internal friction angle,elastic modulus,thickness,etc.of the weak layer in the slope rock mass on the deformation and stability of the inclined and anti-inclined slopes was studied,and the most dangerous parameter combination of layered rock foundation pits containing weak layers was obtained.Secondly,numerical simulation research was conducted on the deformation control effect of slopes in high dip layered rock foundation pits under different support schemes.Based on the most unfavorable rock mass parameter combination obtained in Chapter 2,the deformation laws,horizontal displacement of pile body,bending moment and shear force,internal support axial force,and anchor cable axial force of inclined and anti-inclined slopes under different pile spacing conditions were studied for pile anchor,pile support,and pile support anchor support system.By comparing the deformation and internal force changes of the support structure of different support schemes on the same side slope of the foundation pit,as well as on different slopes with forward and reverse inclinations,the effectiveness of different support schemes on slope deformation control was evaluated.Furthermore,a comprehensive analysis was conducted on the monitoring data of the deep foundation pit support system of the South Third Ring Station of Metro Line 3.By analyzing the horizontal displacement,steel bar stress,concrete strain,concrete support steel bar stress,and axial strain data of the consequent slope and anti-dip slope retaining piles in the monitoring area of the foundation pit,the deformation,stress patterns,and differences of the retaining piles on both sides,as well as the stress and deformation characteristics of the inner support system,were grasped,and the adverse geological phenomena of the consequent slope and anti-dip slopes were reasonably speculated,And the safety and potential optimization space of the existing support scheme for the foundation pit project were discussed.Subsequently,numerical simulation of the construction process of the deep foundation pit at the South Third Ring Station of Metro Line 3 and optimization analysis of the support scheme were carried out.Based on the changes in the slope and support system obtained from the previous text,numerical simulations were conducted to verify the entire excavation process of the foundation pit.The deformation laws of the consequent slope and anti-dip slopes and support systems were analyzed,and the optimization design of the support plan was carried out to obtain the optimal plan for the foundation pit support.Finally,research was conducted on the mechanical model and design calculation method of the retaining pile.In response to the shortcomings of the elastic support method in the mechanical analysis and deformation calculation of foundation pit retaining piles,which requires artificial assumptions about the soil pressure on the pile side,a simplified numerical model method for the calculation of foundation pit retaining piles is proposed.By analyzing the changes in horizontal displacement,bending moment,and lateral pressure of the rock mass in the embedded section of the pile body,the similarities and differences between the simplified numerical model and the elastic support method,as well as the simplified numerical model of foundation pit tilting and antidip slop,are compared.The rationality of the simplified numerical model is obtained,and the rationality of the simplified numerical model is verified by the measured displacement data validation of the foundation pit retaining pile body.