| CM Pile Composite Foundation is a new technology of high Strength Composite Foundation,which is based on the research of stress transfer,bearing capacity,foundation deformation,cushion effect and so on.Under the premise of giving full consideration to economic benefits,controlling construction period and ensuring project safety,how to deal with foundations in complex karst areas has become a new topic for designers.Because the composite foundation of CM pile can mobilize the shallow soil,it can also mobilize the deep soil to participate in the work,so that the combination of its spatial stiffness gradient forms a new high strength stress field.In recent years,CM Pile Composite Foundation has been successfully applied in karst area of Guangdong province.Based on the existing relevant theory,on the basis of CM pile composite foundation by a certain engineering in karst region of guangzhou city as the research background,the CM pile composite foundation by geological exploration data,field test,the long-term settlement observation data collection and analysis,and introducing the theory calculation,reliability analysis,finite element simulation analysis,established the CM pile composite foundation in karst area of the application framework.In this paper,the bearing capacity,settlement,and applicability of the composite foundation of CM pile in the region are systematically analyzed and studied.The main research contents and results are as follows:(1)On the basis of the engineering geological survey report,the geological characteristics of the site and the distribution law of the cave are summarized.The calculation and verification of the results of the CM pile composite composite foundation design and site inspection test were carried out.The error analysis was carried out and the conclusion that the theoretical calculation value was close to the detection result was obtained.Through the analysis of the long-term settlement results of the building,it is concluded that the overall settlement of the building conforms to the general settlement rule of the building and is currently in a stable state.The successful application of the CM pile composite foundation in this project is preliminarily proved.(2)In this paper,the reliability of foundation bearing capacity is calculated and analyzed.According to the corresponding theory and calculation formula,the limit equation of the bearing capacity of CM pile composite foundation is deduced,the Matlab calculation program is compiled by JC method,and the reliability index is obtained.The sensitivity analysis of the random variable in the limit equation is performed and some conclusions are obtained.For example,1)CM pile composite foundation can meet the requirements of vertical bearing capacity,bearing capacity is reliable;2)The variation of the coefficient of variation has a greater influence on the fluctuation of the reliability index,and the increase of the coefficient of variation will reduce the reliability index.3)The variation coefficient of pile end bearing capacity of rigid pile change the biggest influence on reliability index.(3)This paper uses Midas GTS NX finite element software to analyze the bearing capacity and deformation characteristics of CM pile composite foundation.First of all,the finite element simulation of the actual project was carried out.The simulation results were similar to the field test results.Secondly,the influence of load size,cushion modulus on foundation deformation modulus and pile-soil stress ratio is studied,and the soil stress distribution ratio of CM pile composite Foundation,c pile,m pile and pile is obtained. |
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