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为确立西安黄土基床系数的取值范围和经验公式,根据西安地铁采用K_(30)平板载荷试验测得的基床系数资料,归纳西安黄土基床系数的范围及其随深度的变化规律,对比分析K_(30)平板载荷试验、旁压试验、标贯试验及室内固结试验的基床系数测试结果,探讨K_(30)平板载荷试验与其他试验方法间的相关关系。结果表明:在新黄土、古土壤及老黄土地层中基床系数随深度增加总体呈增大趋势,在黄土状土地层中基床系数随深度增加变化规律不明显;西安黄土的水平基床系数K_x以小于垂直基床系数K_v为主,K_x/K_v比值呈现正态分布,且约占试验数据总数81%的K_x/K_v比值分布在0.5~1.0范围;由K_(30)平板载荷试验测得的基床系数与旁压模量、标贯击数均近似呈线性关系,与压缩模量及压缩系数近似呈二元幂函数关系。这些结果可供西安地区隧道、基坑工程的勘察设计参考使用。
In order to establish the range of value and empirical formula of bedrock coefficient of loess in Xi’an, according to the data of bedrock coefficient measured by the K_ (30) slab load test in Xi’an Subway, the range of bedrock coefficient of Xi’an loess and its variation with depth were summarized, The relationship between the K 30 plate load test, the pressure test, the standard test and the bed consolidation coefficient test were compared and analyzed. The relationship between K 30 plate load test and other test methods was discussed. The results show that in the loess, paleosol and old loess strata, the bed coefficient increases with depth, and the bed coefficient in the loess-like soil layer does not change obviously with the depth. The horizontal bed coefficient K_x is less than the vertical bed coefficient K_v, K_x / K_v ratio shows a normal distribution, and K_x / K_v ratio of about 81% of the total test data is distributed in the range of 0.5 to 1.0; K_x is measured by K_ (30) plate load test The bed coefficient is nearly linear with the compressive modulus and the number of standard penetrations, and it has a binary power function relationship with compressive modulus and compressibility. These results can be used for the survey and design of tunnels and foundation pit projects in Xi’an.