载荷试验尺寸效应及地基承载力确定方法探讨

压板载荷试验是目前被普遍采用且认为是最可靠的地基承载力确定方法，但其影响因素多诸如压板尺寸、埋置深度、地基土均匀性、沉降稳定标准等，尤其以压板尺寸对试验结果的影响最大。工程实践表明，利用压板试验确定的地基承载力特征值设计的基础，实测沉降与计算沉降之间的误差较大，在已有研究成果基础上，研究载荷试验尺寸效应及地基承载力确定方法：（1）综述目前地基承载力确定方面存在问题；（2）分析载荷试验的尺寸效应；（3）基于杨光华教授提出的非线性切线模量法，推导并给出了如何利用小压板载荷试验结果得到实际基础的荷载-沉降曲线的方法；（4）给出利用实际基础的p-s曲线确定地基承载力的方法，实现地基安全和沉降双控的目的；（5）由于压板试验只能反映浅层土，文中利用旁压试验确定深层土的地基承载力的方法。具体工程实例结果表明，基于利用小压板获得的参数计算的沉降值更符合实际；研究通过小压板原位测试方法获取沉降计算的岩土体统参数方法，不仅能够提高沉降计算精度，还可促进基础设计理论的发展和设计水平的提高。

Discussion on size effect of plate loading test and determination of bearing capacity of subgrade

The plate loading test is considered as the most wide and reliable method for determing bearing capacity, However, it can be affected by many factors, for instance, the size and buried depth of the load plate, the homogeneity of the soil, the criterion of determining ending of settlement, among which the size of load plate is the most important one. Mass engineering projects show that relatively error can be found between monitoring and predicted settlement when the plate load test is applied for determining the bearing capacity of foundation. Due to the above-mentioned problem, the paper considers the size effect of plate load test and the method for determining bearing capacity based on previous studies by others. The contents include: (1) Summarizing the defects of currently used methods for bearing capacity determination. (2) Analyzing the size effect of load plate. (3) Deriving the method of obtaining the p-s curve for real foundation by plate load test with plate in small size, based on Professor Yang’s theory of nonlinear tangent-modules method. (4) Proposing the method for determining the bearing capacity based on the p-s curve of the real foundation, the method is able to guarantee the safety of foundation and predicting the settlement. (5) Due to the fact that the plate load test is normally used for soils in shallow depth, the paper proposes a method to determine the bearing capacity in deeper soils by pressuremeter test; A project results show that the settlement calculated based on the soil parameters derived from small-size load plate test is closer to monitoring data. The research on deriving soil geotechnical parameters through small-size plate load test not only improves the accuracy of settlement calculation, but also promotes the development of foundation design theory.