Abstract：博士学位论文摘要 The invest igat ion of comp lete st ress2st rain behavio r and comp ressive failu re behavio r of som e Hong Kong rock s are carried ou t. A large num ber of test s have been conducted to study the defo rm at ion and failu re featu res of rock s. Som e in terest ing test resu lt s have been ob tained. These resu lt s show that localized defo rm at ion and failu re st rongly affect the defo rm at ion and failu re p rocess of the specim en s ju st p rio r to the peak st ress and in the po st2peak stage. The two types of failu re modes, nam ely exfo liat ion and shear failu re have been invest igated in detail. Fo r the exfo liat ion failu remode, an experim en tm ethod has been p ropo sed to ob serve the exfo liat ing p rocess. A p ropo sed model has been u sed to exp lain the inf luence of exfo liat ion on the gro ss st ress2st rain cu rve. It is found that the exfo liat ion du ring loading m ay be one of the reason s that a gran ite specim en exh ib it s Class Ê behavio r. The inf luences of m ach ine st iffness con t ro l modes, end con st rain t s, loading rate and conf in ing p ressu re on the test resu lt s have been discu ssed and invest igated. A new classif icat ion m ethod of rock failu re has been p ropo sed. Special at ten t ion has been devo ted to the invest igat ion of the localized defo rm at ion and failu re p rocess of in tact rock in the shear failu re mode. A test m ethod is p ropo sed to detect the p rocess. It is found that the defo rm at ion of rock m aterial m ay be divided in to th ree stages: nam ely un ifo rm stage, p re2peak b ifu rcat ion stage and po st2peak b ifu rcat ion stage. Th is phenom enon has been exp lained by a p ropo sed qualitat ive analysis. It is fu rther found that th is localized p rocessw ill sign if ican t ly inf luence the shape of st ress2st rain cu rves, that is, the localized defo rm at ion is one of reason s that rock disp lays the effect of length to diam eter rat io. A con st itu t ive model is p ropo sed to sim u late the localized defo rm at ion and failu re p rocess. It can sim u late the st rain sof ten ing, st rain localizat ion, effect of length to diameter (L öD ) rat io, un loading2reloading respon s, and elast icmodu lu s degradat ion, etc. Based on the model, a new st rength criterion exp ressed by the relat ive shear disp lacem en t is p ropo sed. Th is criterion cap tu res the comp lex featu res of peak st rength of rock such as the size effect.
