Limit state design codes such as Eurocode 7 require good estimates of displacement to be made for serviceability checks. It is known that the stiffness of overconsolidated soils and weak rocks is highly non-linear and this needs to be taken into account for reliable displacements to be calculated. This paper outlines a relatively simple means of characterising the undrained and drained non-linear stiffness of a wide range of soils and rocks. A series of practical applications are described where the calculated stiffness non-linearity is compared with high-quality field and laboratory test data, including back-analysis of full-scale structures. The non-linear stiffness function requires just four inputs: shear modulus at small strain; shear strength; failure strain; and elastic threshold strain. Applications include: checking advanced test data and calibration of non-linear constitutive models; derivation of field stiffness, including variations with depth; non-linear stiffness curves; and assessing the potential effects of stiffness anisotropy.

中文翻译：

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非线性刚度表征——一个实用的框架

极限状态设计规范（例如 Eurocode 7）要求对位移进行良好估算以进行适用性检查。众所周知，超固结土和软弱岩石的刚度是高度非线性的，需要考虑这一点才能计算可靠的位移。本文概述了一种相对简单的方法来表征各种土壤和岩石的不排水和排水非线性刚度。描述了一系列实际应用，其中将计算出的刚度非线性与高质量的现场和实验室测试数据进行比较，包括全尺寸结构的反分析。非线性刚度函数只需要四个输入：小应变时的剪切模量；剪切强度；失效应变；和弹性阈值应变。应用包括：检查先进的测试数据和非线性本构模型的校准；场刚度的推导，包括随深度的变化；非线性刚度曲线；并评估刚度各向异性的潜在影响。