Based on the stratum characteristics in Xi'an,the structural bearing characteristics of different foundation types and the most unfavorable working conditions were analyzed,with the five metro stations under construction by the pile-beam-arch(PBA)method as the example.The foundation bearing capacity,horizontal shear resistance,anti-overturning capacity,anti-uplift of the foundation,and allowable horizontal displacement of the structure were selected as the basic criteria for evaluating the structural strength and stiffness safety of the foundation structure.The mechanical model of the foundation structure by PBA method was constructed,and the calculation formulas of the structural safety factors under different failure modes were deduced.Some suggestions on the safety factors values in the type selection theory system of the foundation structure by PBA method in Xi'an were put forward.The application scopes of single-row long pile foundation and strip foundation under the column in different strata and buried depths were given.Research results show that when the foundation structure by PBA method in Xi'an is calculated according to the basic criteria of foundation bearing capacity,horizontal shear resistance,anti-overturning capacity,anti-uplift of the foundation,and allowable horizontal displacement of the structure,the safety factors should be not less than 1.2,1.3,1.3,1.6,and 1.4,respectively.The structure selection of the middle column foundation by PBA method is mainly affected by the vertical bearing capacity criterion of the foundation.When the same column span type is adopted,the applicability of the strip foundation under the column in the sandy soil stratum is better than that in the silty clay-sand interbedded stratum and silty clay stratum.The structural bearing capacity of the single-row long pile foundation can be improved by increasing the pile length.Theoretically,the applicability of the single-row long pile foundation under various stratum conditions is better than that of the strip foundation under the column.The composite criteria should be used to comprehensively analyze the applicability of the side pile foundation structure.The applicability of the strip foundation structure under the column is greatly affected by the stratum condition,and the anti-overturning safety of the structure is difficult to meet the requirements under the conditions of silty clay and silty clay-sand interbedded stratum.However,the single-row long pile foundation is mainly affected by its own structural strength and stiffness under various criteria,and there is no significant difference in the applicable burial depths in various strata.The single-row long pile foundation is more applicable for the metro station in Xi'an by PBA method,while the strip foundation under the column can meet the structural safety requirements by expanding the foundation width.11 tabs,10 figs,33 refs.
关键词
地铁车站/洞桩法/基础结构选型/安全性评判准则/力学模型/结构安全系数
Key words
metro station/pile-beam-arch method/foundation structure selection/safety judgment criterion/mechanical model/structural safety factor
维普
万方数据