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正确评估破碎岩体注浆加固后的强度对于岩石工程设计十分重要。基于莫尔库仑强度准则,建立了注浆前后破碎岩体强度增长理论,推导出单轴抗压强度增长率、单轴抗拉强度增长率、内摩擦系数增长率和内聚力增长率之间的关系方程。根据已有的基于BQ的岩体内聚力和内摩擦角的经验公式,推导出注浆后破碎岩体内摩擦系数增长率和内聚力增长率随岩体质量指标增长量(?BQ)变化的表达式。再根据已有的注浆后破碎岩体单轴抗压强度增长率的经验公式和各强度增长率之间的关系方程,得到隐含?BQ的非线性方程,可通过数值解法求出了?BQ的值,进而很容易求得各强度增长率的值。分析表明,随着岩体质量指标由小到大变化,注浆后强度增长率开始较大,并很快减小,而后趋于平缓;一般情况下,内聚力增长率约为摩擦系数增长率的2~5倍,单轴抗压强度增长率约为单轴抗拉强度增长率的2~3倍。
Correctly assessing the strength of grouted rock mass after grouting is very important for rock engineering design. Based on the criterion of Mohr-Coulomb’s strength, the theory of strength increase of rock mass before and after grouting is established, and the relationship between uniaxial compressive strength growth rate, uniaxial tensile strength growth rate, internal friction coefficient growth rate and cohesive force growth rate is deduced equation. Based on the existing empirical formulas of Cohesion and Internal Friction Angle of BQ-based rock mass, the expression of the change of friction coefficient and cohesion increase with the increase of mass index of rock mass (? BQ) is deduced after grouting . Based on the existing empirical formula of the uniaxial compressive strength growth rate of the crushed rock mass after grouting and the relational equation between the strength growth rates, the nonlinear equation of the implicit? BQ can be obtained by numerical solution. BQ value, and then easily calculate the value of the rate of strength growth. The analysis shows that as the mass index of rock mass changes from small to large, the strength growth rate after grouting begins to be larger and decreases rapidly and then tends to be gentle. In general, the growth rate of cohesion is about the growth rate of friction coefficient 2 to 5 times the uniaxial compressive strength growth rate of about uniaxial tensile strength growth rate of 2 to 3 times.