基于旁压试验确定原位土体变形模量方法适宜性探讨

Discussion on the suitability of determining methods for deformation modulus of in-situ soils based on pressuremeter test

现行《铁路工程地质原位测试规程》《工程地质手册》中均建议了利用原位旁压试验曲线计算地基土变形模量的方法,不同确定方法针对不同场地不同类型地基土的适宜性值得进一步探究。基于地应力平衡,利用ABAQUS软件建立了能够计算原位地层变形模量的有限元数值分析模型:首先对旁压试验数值分析模型的重要影响参数(模型尺寸、侧压力系数和水平径向应力的敏感性)进行详尽的分析,基于参数敏感性分析的结果进一步优化了数值模型;再利用实测旁压曲线采用数值参数反演的方法获得地基土的变形模量,同时与现行规范及手册建议的计算方法进行对比分析,探讨了不同方法获得结果的差异;最后给出了利用旁压试验获取原位土体变形模量的建议。

The different methods for computing the deformation modulus of in-situ soils based on the pressuremeter test have been advised in the current standards and handbooks.The suitability of these suggested methods for variable soil layers in different areas still need to be investigated.The numerical model is established for determining the in-situ deformation modulus of soils based on the results of pressuremeter tests using the ABAQUS finite element software,in which the geostatic balance is considered.The size of the model,lateral pressure coefficient and horizontal radial stress are identified to be the critical parameters for simulating the pressuremeter tests.The parameter sensitivity analysis on these critical parameters is done in detail.Based on the results of the sensitivity analysis,the numerical model has been simplified.Furthermore,the true deformation modulus of foundation soils is determined by an inversed method based on the measured pressuremeter curves.The deformation moduli using the recommended methods from the standards and handbooks is compared to the true ones.The discrepancy among the different methods on determining the deformation modulus have been explored.The suggestions on accurately determining the in-situ deformation modulus have been given based on the pressuremeter tests which offer reference for the engineering design.