裂隙岩体的一体两介质模型抗剪性能研究

EXPERIMENTAL INVESTIGATION ON SHEAR PERFORMANCE OF UNI-BODY BI-MATERIAL MECHANICAL MODEL FOR FISSURED ROCKS

裂隙薄弱层与岩石接触面的抗剪强度是影响裂隙岩体稳定的重要参量。采用一体两介质力学模型研究裂隙岩体接触面的力学性能。按照著名的Barton试验所采用的粗糙界面,以砂浆和混凝土构造5种JRC曲线的接触面,并采用自创的双指标描述系统——考虑粗糙度的改进分维值指标Rd和考虑起伏度的形状因子λ对接触面形貌进行定量描述。Rd-λ描述系统的优点在于:不仅能描述粗糙程度,还能解释同一粗糙界面上当受力方向不同时,其界面抗剪力学性能显著不同的事实。通过直剪试验,分析岩体接触面的破坏状态及剪切应力-剪切位移曲线,确定影响抗剪强度的主要因素为接触面粗糙起伏形貌、法向力、界面材料的黏结强度等,并借助试验结果,拟合得到考虑上述影响因素,以Rd-λ描述系统表达的剪切强度公式。将提出的剪切强度公式与其他试验获得的剪切试验结果做对比分析,证实该剪切强度公式的正确性。

For the interface of the weak structural plane and the rock mass,the shear strength is an important parameter to affect the fissured rocks stability.The two-material mechanical model and direct shear test are employed to study the fissured rocks？ mechanical properties of the interface.According to the famous Barton＇s rough description method（JRC value）,five different JRC curves are chosen to make a series of two-material mechanical model specimens.Each specimen is casted with the mortar and concrete on the both sides of the interface.Besides,the interface is rough along one direction（shear direction）,but un-rough along another.The rough degree of interface is also described with the modified fractal index Rd and shape factor λ.The Rd-λ description system can not only describe the roughness of the interface,but also explain the experimental phenomenon that the same rough surface shows different mechanical behaviors if the shear stress direction on the surface is changed.Through the direct shear tests,the failure patterns of the interface in fissured rock mass and their shear stress-shear displacement curves are obtained.The main influence factors,such as the material strength ratio k,the surface appearance,the normal stress σ and the cohesional strength C,are determined and analyzed.Based on the analysis,a shear strength formula,in which the main influence factors are included and the rough interface appearance is expressed with Rd-system is proposed.Finally,the formula calculating result is compared with test results provided by other researcher and its validity is testified.