An experimental study of the mechanical properties of the Bimrock rock mass with different cementing strength based on orthogonal tests
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摘要: Bimrock在不同胶结强度下的力学特性鲜有研究,而胶结强度对Bimrock力学特性和变形破坏特征有着重要影响。为探究不同胶结强度对Bimrock力学特性的影响规律,通过正交试验设计法,开展Bimrock基质配比试验,对不同配比基质试样的强度力学参数进行参数敏感性分析,基于正交试验结果,制作不同胶结强度的Bimrock试样,通过单轴压缩试验,分析不同胶结强度对Bimrock力学特性的影响。结果表明:Bimrock试样的单轴抗压强度和弹性模量与其胶结强度呈正相关,从弱胶结到强胶结,单轴抗压强度从11.02 MPa增加到34.21 MPa,弹性模量从2.11 GPa增加到5.57 GPa;随着胶结强度的增加,试样在变形至破坏的各阶段表面裂纹数量均减少;强胶结试样的压缩破坏模式表现为单条主裂纹的贯通破坏,破坏时间较短,脆性破坏明显;中等胶结试样发生整体与局部剪切破坏,表现为一条明显贯穿整个试样和一条仅贯穿试样下半部分的剪切破坏面;弱胶结试样发生横向拉张破坏,可见多条沿竖直方向的张拉裂纹,局部出现张剪破坏并存的破坏特征,从变形到破坏产生的裂纹较多且较为破碎,破坏时间相对较长。Bimrock岩体工程问题复杂而且较难处理,针对Bimrock力学特性与变形破坏特征的研究对工程建设以及地质灾害防治有重要意义。Abstract: The mechanical properties of Bimrock under different cementation strength are rarely studied, and the cementation strength has an important influence on the mechanical properties and deformation and failure characteristics of Bimrock. In order to explore the influence of different cementation strength on the mechanical properties of Bimrock, the proportion test of Bimrock cementation matrix was conducted by using the orthogonal test design method, and the parameter sensitivity analysis was carried out on the strength mechanical parameters of the samples with different proportions of matrix. Based on the orthogonal test results, the Bimrock samples with different cementation strength were made, and the influence of different cementation strength on the mechanical properties of Bimrock was analyzed through the uniaxial compression test. The results show that the uniaxial compressive strength and elastic modulus of the Bimrock specimens are positively correlated with their cementation strength. From weak cementation to strong cementation, the peak uniaxial compressive strength increases from 11.02 MPa to 34.21 MPa, and the elastic modulus increases from 2.11 GPa to 5.57 GPa, respectively. With the increasing bonding strength, the number of surface cracks in each stage from deformation to failure decreases. The compression failure mode of the strongly bonded specimen is the through failure of a single main crack, with short failure time and obvious brittle failure. The overall and local shear failure occurred in the moderately cemented specimen, which is represented by a shear failure surface that obviously penetrates the whole specimen and a shear failure surface that only penetrates the lower part of the specimen. The weak cementation sample is subject to transverse tensile failure. A number of tensile cracks parallel to the vertical direction can be seen, and the failure characteristics of coexistence of tensile and shear failure can be seen locally. From deformation to failure, there are many cracks that are relatively broken, and the failure time is relatively long. The engineering problems of Bimrock are complex and difficult to deal with. The research on the mechanical properties and deformation and failure characteristics of Bimrock is of great significance for engineering construction and geological disaster prevention.
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Key words:
- Bimrock /
- strength of cementation /
- failure mode /
- uniaxial compressive strength
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表 1 各因素水平值
Table 1. Level of the factors
水平组数 石英砂/% 水泥∶石膏 水含量/% 水平1 30 1.8∶1 19 水平2 45 2.4∶1 20 水平3 60 3.0∶1 21 表 2 正交配比方案
Table 2. Orthogonal matching schemes
方案 J1 J2 J3 J4 J5 J6 J7 J8 J9 石英砂/% 30 30 30 45 45 45 60 604 60 水泥∶石膏 1.8∶1 2.4∶1 3.0∶1 1.8∶1 2.4∶1 3.0∶1 1.8∶1 2.4∶1 3.0∶1 水含量/% 19 20 21 20 21 19 21 19 20 表 3 各配比方案试样结果
Table 3. Experimental results of the matching schemes
方案 J1 J2 J3 J4 J5 J6 J7 J8 J9 σc/MPa 20.21 23.96 29.12 16.13 21.92 23.96 8.04 12.64 14.62 E/GPa 3.24 3.86 5.01 3.25 3.51 4.50 2.24 2.70 3.68 c/MPa 2.18 2.61 3.08 1.42 1.79 2.15 0.40 0.78 1.22 φ/(°) 42.5 46.7 34.4 37.6 48.5 42.3 27.4 38.6 36.4 表 4 各因素敏感性分析表
Table 4. Sensitivity analysis of the factors
水平组数 单轴抗压强度/MPa 弹性模量/GPa 黏聚力/MPa 内摩擦角/(°) A因素 B因素 C因素 A因素 B因素 C因素 A因素 B因素 C因素 A因素 B因素 C因素 水平1 24.43 14.79 18.94 4.04 2.91 3.48 2.62 1.33 1.70 41.20 35.80 41.10 水平2 20.67 19.51 18.24 3.75 3.36 3.60 1.79 1.73 1.75 42.80 44.60 40.20 水平3 11.77 22.57 19.96 2.87 4.40 3.59 0.80 2.15 1.76 34.10 37.70 36.80 极差 12.66 7.78 1.72 1.17 1.49 0.12 1.82 0.82 0.06 8.70 8.80 4.30 表 5 不同胶结强度Bimrock及纯基质的强度参数
Table 5. Strength parameters of Bimrock and pure matrix with different bonding strengths
试样编号 σc/MPa E/GPa 峰值应变
/%σc增量
百分比/%E增量
百分比/%B7 11.02 2.11 0.76 B5 27.18 4.19 0.96 146.64 98.58 B3 34.21 5.57 0.95 210.44 163.98 J7 8.04 2.24 J5 21.92 3.51 J3 29.12 5.01 -
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