Study On Vertical Support Technology Of Bedding Rock Building Slope In Mountainous City

With the rapid development of China’s national economy,the scale and quantity of urban infrastructure are gradually expanding,which makes the urban construction land more and more tense.The shortage of land makes the conditions of some construction projects limited.Taking Chongqing as a mountain city,many buildings are built close to the mountains,half digging and half filling,forming various types of building slopes.In order to effectively use the tense construction land and improve the land utilization rate,vertical excavation is used.Therefore,it is very necessary to study the slope vertical support technology,which can not only support the slope safely,applicable and economically,but also make full use of urban land resources effectively and reasonably.Taking the bedding rock slope of Chongqing Fifth People’s Hospital Relocation Project as the research object,this article studies the vertical support technology of the slope.By using the orthogonal test method and Midas GTS finite element numerical simulation,the influence of various support parameters on the anti slide pile displacement,road displacement and anti slide pile stress is analyzed,It is expected to provide reference for similar vertical support engineering of bedding rock slope.The main achievements are as follows:1.The basic support forms for bedding rock slope are summarized,including bolt(cable)support,bolt(cable)retaining wall support,rock bolt shotcrete support,pile plate retaining wall support and slope rate method.The concept of bedding rock slope and its preliminary judgment basis are summarized.The internal and external factors affecting the slope stability are summarized,including the dip angle of rock layer,the nature of rock mass,the nature of rock mass structural plane,in-situ stress,the action of water,earthquake,Fenghua and various construction activities.Five failure geometries(plane failure along structural plane,circular slip failure,wedge failure,collapse failure,and toppling failure)and six failure mechanisms(creep compression cracking failure,slip tension cracking failure,slip bending failure,bending tension cracking failure,bedding slip failure,and slip toe shearing failure)of bedding rock slope are analyzed and summarized.The selection principle of supporting measures for bedding rock slope is put forward through analysis.2.two supporting schemes are proposed: scheme 1(rectangular pile + anchor cable support is adopted,and the support method is based on the conventional experience of the project,considering that the anti sliding effect of rectangular section pile is better than circular pile)and scheme II(circular pile + anchor cable support is adopted,and the circular anti sliding pile can be used for hole forming by mechanical means).The finite element model of excavation process is established by using the Midas GTS anisotropic joint rock constitutive model.It is concluded that the horizontal displacement of pile body and the total displacement of road increase linearly with the increase of excavation depth;The support effect of scheme 1 and scheme 2 can meet the requirements of the specification.Combined with the comparative analysis of safety,construction period and cost,scheme 2 has significant advantages for the project,which is more suitable for the project practice,and scheme2 is selected.Through comparison and selection,it is important to compare and select the scheme.The support of slope engineering should be based on local conditions.The specific problems are analyzed in detail,and are not limited to the conventional engineering experience.3.Taking the horizontal displacement of the anti slide pile top,the horizontal displacement of the anti slide pile anchorage point,the total displacement of the road on the top of the slope and the maximum stress of the anti slide pile as the analysis and evaluation indexes,the influence of the diameter of the anti slide pile,the spacing between the anti slide piles,the incidence angle of the anchor cable and the vertical spacing of the anchor cable on the anti slide pile are studied,Research surface: the diameter of the anti slide pile has the greatest influence on the horizontal displacement of the top of the anti slide pile;The diameter of the anti slide pile and the vertical spacing of the anchor cable have the greatest influence on the horizontal displacement of the embedded point of the anti slide pile;It is suggested that the two factors should be considered comprehensively to control the total displacement of the road;The diameter and spacing of anti slide pile have significant influence on the maximum stress value of anti slide pile,and the diameter of anti slide pile has the greatest influence.It is suggested that the maximum stress of anti slide pile should be controlled by increasing the diameter of anti slide pile.Based on the comprehensive analysis of the four support parameters,it is suggested that the diameter of anti slide pile should be 1.8m,the distance between piles should be 3.5m,and the inclination angle of anchor cable should be 10 °,The vertical spacing of anchor cable is recommended to be 3.5m.