华北水利水电大学学报(自然科学版)

【目的】为了克服在深厚覆盖层上建设高土石坝的难题，开展深厚覆盖层的现场试验与室内试验，为坝基与坝体设计提供科学依据。【方法】针对拟建的中波水电站坝址河床深厚覆盖层开展现场原位旁压试验，获取不同地层的地基承载力参数；通过有限元数值分析方法模拟旁压试验过程并分析其变形机理，基于遗传优化算法对旁压试验进行反演，获得坝基沉降变形分析所需的各地层邓肯-张E-B模型参数；结合坝基土层开展室内大型三轴试验，获得邓肯-张E-B模型参数，提出室内试验参数与反演参数的折减公式，并应用工程案例对折减公式进行比较验证。【结果】(1)旁压试验的结果表明，覆盖层的原位结构性与试验段水平土体的压密特性是反演参数结果比三轴试验参数结果大的主要原因。(2)有限元数值分析的反演曲线斜率与现场试验实测曲线的一致，证实了数值反演旁压试验规律的准确性。(3)提出的室内试验参数与反演参数的折减公式应用于工程案例，验证效果良好，说明折减公式的预测性好，能够实现室内试验参数结果与反演分析参数结果之间的相互转换。【结论】通过现场旁压试验反演本构模型参数并经过公式合理折减能够准确获得土体材料的变形计算参数，为类似的堆石坝工程提供有益参考。

【Objective】 To overcome the difficulties in constructing high earth-rockfill dams on deep overburden layers, field tests and laboratory tests on deep overburden layers are carried out to provide a scientific basis for the design of dam foundations and dam bodies. 【Methods】 Field in-situ pressuremeter tests were conducted on the deep overburden layers of the riverbed at the proposed Zhongbo hydropower station site to obtain the foundation bearing capacity parameters of different strata. Finite element numerical analysis was employed to simulate the pressuremeter test process and analyze its deformation mechanism. Based on a genetic optimization algorithm, back-analysis of the pressuremeter tests was performed to obtain the Duncan-Chang E-B model parameters of each stratum required for dam foundation settlement and deformation analysis. Large-scale laboratory triaxial tests on the dam foundation soils were also carried out to obtain the Duncan-Chang E-B model parameters. A reduction formula relating laboratory test parameters and back-analysis parameters was proposed. An engineering case study was applied to compare and validate the reduction formula. 【Results】(1) The pressuremeter test results indicated that the in-situ structure of the overburden layer and the compaction properties of the horizontal soil in the test section were the primary reasons why the back-analysis parameters were larger than those obtained from triaxial tests.(2) The slopes of the back-analysis curves from the finite element numerical analysis aligned with the measured curves from field tests, confirming the accuracy of the numerical back-analysis in capturing the pressuremeter test behavior.(3) The proposed reduction formula for laboratory test parameters and back-analysis parameters was applied to the engineering case study, and the validation results were satisfactory, indicating that the reduction formula had good predictive capability and enabled conversion between parameters obtained from laboratory tests and those from back-analysis. 【Conclusion】 The deformation calculation parameters of soil materials can be accurately obtained by back-analyzing constitutive model parameters through field pressuremeter tests and applying a reasonable reduction formula, thereby providing valuable references for similar earth-rockfill dam projects.