A New Method for Estimation of Shear Strength of Rock Mass Using Micro-craks Made by Freezing and Thawing Cycles
A New Method for Estimation of Shear Strength of Rock Mass Using Micro-craks Made by Freezing and Thawing Cycles
复制标题
利用冻融循环产生的微裂隙估算岩体抗剪强度的新方法
DOI：
10.5110/jjseg.21.181
复制
发表时间：
1980
期刊：
影响因子：
--
通讯作者：
M. Negishi
中科院分区：
文献类型：
--
作者：
M. Negishi
由于裂隙岩体的强度与完整岩石试件的强度相差很大，为了建立更实用的裂隙岩体强度与完整岩石试件强度的关系式，制备了冻融循环下的裂隙岩体试件，以及它们的单轴抗压强度与P-结果表明，这种关系与裂隙岩体的波速关系十分相似，是一种十分有用的室内试验方法。由于其均匀的质地和适当的硬度，将焊接凝灰岩片用于该实验。根据完整岩体和裂隙岩体的室内试验结果，可按下式计算岩体抗剪强度的近似值：τ m_0 =τ p_0（Vpm/Vp_0）n（单轴抗压强度qu 0 =10-100 kg/cm 2），n=1.3- 1.7中硬岩石（qu 0 =100-500），n=1.6- 2.8硬岩I类（qu 0 =500-1，000），n=2.7- 4.0 II类硬岩（qu 0 ≥ 1000），n=4.0-5.5τm0：岩体抗剪强度（内聚力）τp0：岩石完整试件的抗剪强度（内聚力）Vpm：岩体纵波速度Vp 0：岩石完整试件的纵波速度。此外，在北海道的10个地方进行了岩石完整试件抗剪强度与岩体块体抗剪强度的关系，可近似表示为：τ m-b 0 =τp0（Vpm/Vp 0）N式中，对于软岩，N=3.0- 3.5中硬岩，N =3.5- 5.5 Ⅰ类硬岩，N=5.5- 8.0 Ⅱ类硬岩，N≥8.0τ m-b 0：现场块体剪切试验获得的岩体抗剪强度（粘聚力，kg/cm ~ 2）在一般建设规划中，后一值（τ m-b 0）已被普遍采用。但必须认识到τm0和τ m-b 0的相互关系，并根据大坝、隧洞和岩体大断面边坡稳定等的安全性目的来应用。
As it is widely recognized that there is a large difference in strength between rock mass with fissures and intact test-pieces of rock, the author aimed to establish more useful equations that bind both strengths.For this purpose, test-pieces with numerous micro cracks made by freezing and thawing cycles were prepared, and the relation between their uniaxial compressive strength and P-wave velocity was investigated.The result showed that this relation is considerably similar to that of rock mass with fissures and indicates that this is a very useful method in laboratory.Test-pieces of welded tuff were used for this experiment because of its uniform texture and appropriate hardness. On the basis of the results of laboratory experiments on the test-pieces of intact and cracy rock, an approximate value of shear strength of rock mass can be calculated by the following equation:τm0=τp0 (Vpm/Vp0) nwhere, in case of soft rock (uniaxial conpressivestrength qu0=10-100 kg/cm2), n=1.3-1.7medium hard rock (qu0=100-500), n=1.6-2.8hard rock class I (qu0=500-1, 000), n=2.7-4.0hard rock class II (qu0≥1, 000), n=4.0-5.5τm0: shear strength of rock mass (cohesion)τp0: shear strength of intact test-pieces of rock (cohesion)Vpm: P-wave velocity of rock massVp0: P-wave velocity of intact test-pieces of rock.Furthermore, the relation between shear strength of intact test-pieces of rock and that of rock mass obtained by blok shear tests at 10 localities of Hokkaido, can be approximately expressed by the following equation:τm-b0=τp0 (Vpm/Vp0) Nwhere, in case of soft rock, N=3.0-3.5medium hard rock, N=3.5-5.5hard rock class I, N=5.5-8.0hard rock class II, N≥8.0τm-b0: shear strength of rock mass obtained byin-situ block shear tests (cohesion, kg/cm2)In planning of general construction the latter value (τm-b0) has been commonly used. However, the differerence of the two values (τm0 and τm-b0) must be recognized, and their application should be made according to the purpose of safety of dam, tunnel and slople stability of large cutting in rock mass, etc.