基于DILSSVM的岩石强度预测研究

PREDICTION OF ROCK STRENGTH WITH DIAGONAL INTERSECTION LSSVM

为解决经典强度准则预测岩石破坏强度不准确的问题，本文使用交叉最小二乘支持向量机（DILSSVM）在单轴及三轴加载情况下对岩石强度进行预测。将现场和实验室试验得到的各种岩石相关数据划分成训练和验证子集。将抗压强度σc和最小主应力σ3作为输入值，最大主应力值σ1 f作为输出值训练DILSSVM。使用训练后的DILSSVM预测岩石破坏时的σ1 f，同时使用训练子集反演Hoek－Brown经验公式的常数m。使用测试数据对训练后DILSSVM预测的目标岩石强度的准确性进行验证，同时将测试数据带入2类Hoek－Brown（m值的取值不同）经验公式预测目标岩石强度σ1 f。比较DILSSVM和Hoek－Brown预测结果，表明：DILSSVM预测结果的均方差减小了45％～55％，决定系数增加了0.055～0.085，更接近于1。说明DILSSVM对岩石强度的预测范围较宽，且适合岩石种类多变的复杂非线性情况。

The classical failure criteria for prediction of rock strength can not be accurate.This study uses the diagonal intersection least squares SVM（DILSSVM）as new method for prediction of the rock strength in a wide loading such as uniaxial and triaxial loading.For each rock type,data obtained from field experiments and laboratory experiments are divided into training and test sets.DILSSVM is employed to train with the compressive stress （σc）and minor principal stress （σ3）and to predict the value of major principal stress （σ1f）at failure.The training sets are used in regression analysis for m in Hoek-Brown （H-B）equation.Then,the test sets are used to examine the accuracy of target rock strength with DILSSVM after training and these of the two H-B model （with different m）.Comparison of the results of the DILSSVM with the two H-B models shows that the DILSSVM always＆nbsp;has less root mean squared error（decreased 45%~55%）and higher coefficient of determination（enhanced 0.055~0.085,near to 1 ）.The DILSSVM shows better flexibility in σ1f at failure in each rock type and a wide loading range.