Research Initiation: Experimental Investigation and Constitutive Modeling of Cohesionless Soil Under Cyclic Loading

在涉及土壤的工程设计中，可能最常见的问题是计算由于对土壤施加一般应力状态而产生的运动。直到最近十到二十年，计算小荷载(与引起坍塌的荷载相比)引起的非常小的移动是可行的，或者计算坍塌荷载并假设移动太大而变得没有必要计算它们。对于两种极端都不成立的常见案件，有必要适用“工程判断”。随着现代数字计算机的出现，研究人员正在对这类问题进行双管齐下的攻击。一种模式包括尝试测量广义土壤属性(对施加应力的广义状态作出响应的完整应变状态)和开发描述土壤响应的模型。第二种模式涉及到数值方法的发展，因此所得到的土壤性质可以用来预测现场的质量运动。这项建议涉及第一种模式。这项研究的目标是对清洁砂样对复杂应力状态的响应进行可靠的测量，然后拟合适当的模型，以允许对所产生的特性进行分析描述。所谓的中空圆柱体装置将被用来测量性能。将尝试各种本构模型。将使用单调加载(直接加载到破坏)和循环加载(反复施加小于破坏应力的应力)。

Perhaps the most common problem in engineering design involving soils, is the problem of calculating the movements that result from application of general states of stress to the soils. Until the last ten to twenty years, it was feasible to calculate either the very small movements that resulted from small loads (compared to the load that causes collapse), or to calculate collapse loads and assume that movements were so large that it became unnecess- ary to calculate them. For common cases in which neither extreme was valid, it was necessary to apply "engineering judgement." With the advent of modern digital computers, researchers are engaged in a two-pronged attack on this class of problem. One mode involves attempts to measure generalized soil properties (complete state of strain in response to a generalized state of applied stress) and development of models to describe the soil response. The second mode involves development of numerical methods so the resulting soil properties can be used to predict mass movements in the field. This proposal involves the first mode. The goal of this research is to perform reliable measurements of the response of samples of clean sands to complex states of stress, and then to fit appropriate models to allow analytic description of the resulting properties. The socalled hollow-cylinder device will be used to measure properties. A variety of constitutive models will be tried. Both monotonic loading (load directly to failure) and cyclic loading (repeated application of stresses less than the failure stresses) will be used.