深埋隧洞大理岩卸载路径真三轴强度参数研究

 为研究深埋隧洞围岩卸载路径破坏特性，在现场深埋试验平洞内进行大理岩原位高压真三轴卸载试验，获得大尺度(50 cm×50 cm×100 cm)、高应力( =11.2 MPa)、真三轴( ＞ ＞ )、卸 破坏状态下，能反映深埋隧洞围岩实际应力状态和隧洞开挖应力路径的大理岩全过程应力–应变曲线和三轴强度。在高压卸载路径大理岩原位真三轴试验基础上，引入H-B经验强度准则研究大理岩卸载路径真三轴强度参数。研究成果表明：(1) 对于大理岩卸载真三轴原位试验，按H-B经验强度准则评估卸载路径真三轴强度偏低情况较多，评估经验参数s = 0.003 951 7，mb = 3.414，而由试验成果反算s = 0.095 53，mb = 12.208。(2) 在H-B经验强度准则基础上，按M-C强度准则，评估大理岩卸载真三轴试验强度参数：tan? = 1.39，c = 6.61 MPa，评估未扰动大理岩卸载真三轴强度参数：tan? = 1.60，c = 6.73 MPa，前者可代表卸荷损伤岩体。

STUDY OF TRUE TRIAXIAL STRENGTH PARAMETERS IN UNLOADING PATH OF MARBLES IN DEEP TUNNEL

In order to study the failure characteristics of the deep surrounding rocks in unloading path,in-situ true triaxial unloading tests under high pressure were carried out in the field deep experimental adit.The tests have features such as large scale(50 cm ×50 cm×100 cm),high stress(= 11.2 MPa),unloading fracture of.This true triaxial test can represent the real stress states of surrounding rocks of deep tunnel and the complete stress-strain curve of marbles in tunnel excavation stress path;and the triaxial strength of rock mass can be obtained.Based on the in-situ true triaxial test of marbles under high pressure in unloading path,Hoek-Brown(H-B) empirical strength criterion is adopted to study the true triaxial strength parameters of marbles in unloading path.The research results are as follows:(1) The values of true triaxial strength parameters in unloading path which are evaluated by using H-B empirical strength criterion may be relatively lower than those in in-situ true triaxial unloading test.The evaluated empirical parameter s is 0.003 951 7,is 3.414.However,the inverse computation parameters according to the test results s = 0.095 53,is 12.208.(2) Based on the evaluated results of rock strength by using H-B empirical strength criterion,Mohr-Coulomb criterion is used to evaluate the values of strength parameters.The true triaxial strength parameters of marbles in unloading path,tan is 1.39,c is 6.61 MPa,while the true triaxial strength parameters of undisturbed marbles in unloading path,tan is 1.60,c is 6.73 MPa.The former can stand for unloading damage rock mass.