新型离心机串联模型试验方法及其初步应用研究

Study on method of a new centrifugal tandem model test and its preliminary application

为解决以往离心机试验中将大型地质物理模型过渡缩尺时无法与离心加速度相匹配的问题,在综合分析以往离心试验技术的基础上,结合现有离心试验技术的不足,提出新型离心机串联模型试验技术。该技术通过两次量纲变换,即在模型设计阶段,原型地质体经过第一次量纲变换至常规模型试验尺度(m倍),然后经过第二次量纲变换换算至离心模型试验尺度(n倍),将模型缩小至原来的1/mn。第一次变换将模型进行较大尺度的缩减,因此第二次将其变换至离心试验尺度时将具有较大的灵活度,能够适应承载能力较小的离心机模拟高程较大的地质体的工作特征。此技术实现了将天然地质模型缩尺至离心机试验箱内,并结合弱化岩土力学强度的方法,从而解决大尺度地质结构模型模拟中存在的缩尺困难的问题。结合我国西南某水电站边坡开展了初步验证,结果表明,串联试验理论能较好地满足大型离心机模型试验的要求,可再现大型地质体变形破坏的整个过程,该技术较好地解决了蓄水过程中边坡的变形模拟问题。

In order to solve the problem of that large-scale geophysical model cannot be matched with the centrifugal acceleration during the transition of scale in previous centrifugal model test, a new technology of centrifugal tandem model test is put forward herein in combination with the existing technology of centrifugal model test on the basis of the comprehensive analysis made on the previous technologies of centrifugal model test. For this technology, two times of dimensional transformation are made, i.e. firstly transforming the dimension of the prototypical geological body into the conventional model test dimension(m times), and then transforming into the dimension of the centrifugal model test(n times) through the secondary dimension transformation, thus reducing the model into 1/mn of the original one. During the first transformation, the model is reduced with a larger scale, and then a larger flexibility is obtained during transforming it into the scale for the centrifugal model test when the secondary transformation, which can adapt the working characteristics of simulating the geological body of larger elevation with the centrifuge with smaller bearing capacity. This technology realizes to reduce the scale of the natural geological model into the centrifuge test box and then solve the problem from the difficulty of reduced-scale in the simulation of the large-scale geological structure model in combination with the method of weakening strength of geotechnical mechanics. A preliminary verification is carried out according to the slope of a hydropower station in Southwest China. The result shows that the theory of the tandem model test can better meet the requirement of the large-scale centrifugal model test and reproduce the whole process of the failure caused by the deformation of large-sized geological body, thus satisfactorily solve the problem of the simulation on the slope deformation during reservoir impoundment.