含一阶和二阶起伏体节理剪切强度的试验研究

EXPERIMENTAL STUDY OF SHEAR STRENGTH OF JOINTS WITH FIRST-ORDER AND SECOND-ORDER ASPERITIES

利用高强石膏材料浇注含不同一阶和二阶起伏度的岩体节理模拟试件,通过节理在不同一阶和二阶起伏度及法向应力下的常法向荷载剪切试验,对其剪切强度特性进行研究,分析一阶和二阶起伏度及法向应力对剪切强度的影响规律。试验结果表明:含二阶起伏体节理试件的剪切强度-剪切位移曲线有多个峰值剪应力出现,只含一阶起伏体节理的峰值剪应力不明显;节理剪切强度随着一阶和二阶起伏度及法向应力的增大而增大;随着二阶起伏度与一阶起伏度比值的增大,剪切强度先增大后降低。对试验数据进行回归分析,提出能反映一阶和二阶起伏度及法向应力影响的剪切强度经验公式。

Simulated rock joint samples with different first-order and second-order asperity heights are casted by high strength gypsum material.A series of CNL（constant normal load） shear tests are carried out to study the shear strength characteristics of joints with different first-order and second-order asperity heights under different normal stresses.The influences of first-order and second-order asperity heights and normal stress on shear strength are analyzed.Based on the experimental results,it can be found that the joint samples with second-order asperity have multi-peak shear stresses,while the joint samples only with first-order asperity have not apparent peak shear stress.The shear strength increases with the increasing first-order and second-order asperity heights and normal stress.With the increasing ratio of second-order asperity height to first-order asperity height,shear strength first increases and then decreases.Finally,an empirical formula is proposed by regression analysis of experimental data to predict the shear strength.The formula can reflect the influences of first-order and second-order asperity heights and normal stress on shear strength.