岩体原位流变荷载试验的力学参数与模型反演

根据现场岩体原位测试的60m和70m处两试验点的流变变形曲线,首先通过曲线特征筛选出了能够描述其变形特性的流变模型(三参量固体模型,Burgers模型),基于粘弹性分析理论及两步反分析法思路,建立了荷载试验的三参量固体模型、Burgers模型的位移优化反演格式,利用分级加载所获得的瞬时弹性位移,反算出了两试验点处的岩体弹性体积模量K、剪切模量G0和变形模量E0,并由优化反演方法获得了两模型的所有流变参数G1,η1,η2和E1以及长期弹性模量E∞。利用所获得的粘弹性参数分别计算出了在不同载荷下两种模型的理论解析曲线,并与实测曲线进行了分析对比,最终获得了能够较真实地描述试验区域岩体流变变形特性的最佳模型,即三参量固体模型。通过对比分析验证了所用思路及方法的正确性和实用性,文中方法虽然应用于流变荷载实验情况,但其具有一定的普遍意义,可应用于不同状况的流变实验的参数确定和模型反演。

Back Analysis of Mechanical Parameters and Model of Rheological in-situ Loading Test for Rock Mass

According to the rheologic deformation curve at 60m and 70m points in in-situ rock mass test, the three-parameter solid model and Burgers model, which could describe the deformation characteristic of in-situ rock mass was first selected by analyzing the curve characteristic from common rheologic models. Based on the viscoelastic theory and the method of two-step inverse analysis, the inverse analysis formulas of displacements were set up for the two models. The elastic instantaneous displacements under different loading levels were used for inverse analysis of the elastic volume modulus, shear modulus and deformation modulus of the rock mass within the two tests regains, and the rheologic parameters and elastic long-term modulus of the two models were obtained by the optimization method of inverse analysis. The theoretically analytical curves of the two models under different loading levels were calculated utilizing the obtained viscoelastic parameters, and compared with measurement curves. By the end, the optimal model which can better describe actual rheologic deformation of rock mass in the test area was gotten, that is the three-parameter solid model. By contrasting and analyzing, the method and the calculating process proposed in this paper are correct and useful. Although the method was applied to the rheologic loading tests, however it has a common significance. It may be used for determining the parameters of rheologic tests and for inverse analysis of the rheologic models under the conditions of different loading levels.