砂卵石层基床系数取值试验对比分析

Comparison and Analysis on Selection of Coefficient of Foundation bed for Sand and Cobble Layer

通过对K30载荷试验、旁压试验和动力触探试验成果获得基床系数进行分析,探讨了砂卵石地层基床系数测试方法的可靠性。试验数据显示,砂卵石层的基床系数取值在密实程度基础上应充分考虑沉积年代、应力历史等因素。通过对砂卵石地层K30载荷试验、旁压试验、重型圆锥动力试验获取的基床系数和规范法建议的基床系数进行对比,K30载荷试验获取的基床系数结果较能真实反映地基基床系数取值。考虑到K30载荷试验实施难度较大,可以通过旁压试验和重型圆锥动力触探试验结果引进折减系数的方式获取基床系数。通过对比,砂卵石地层通过旁压试验获取基床系数,修正系数可采用0.20~0.40;动力触探统计结果获取基床系数,其修正系数可采用0.3~0.4。

Through analysis on the results of K30 load test,PMT and dynamic penetration test,reliability of the testing method for coeffi-cient of foundation bed of sand and cobble layer. The test data present that selection of coefficient of foundation bed,based on the com-paction degree,shall fully consider factors such as deposition age,stress history,etc. Through comparison of coefficients of foundation bed from K30 load test,PMT and DPT,and that recommended in the technical specification,the coefficients of foundation bed from K30 load test enables to truly reflect the selection of coefficient of foundation bed. In consideration of difficulty in performing K30 load test,the coefficient of foundation bed may be derived from,with introduction of deduction factor,the test results of PMT and DPT. Through comparison,the correction factor for the coefficient of foundation bed by PMT for the sand and cobble stratum takes 0.20 ~ 0.40;that by DPT,the correction factor takes 0.30 ~ 0.40.