The wave velocity of a rock mass and the Hoek-Brown criterion are introduced to enable the building of a calculation model of the range of values of horizontal geostresses (σH) in an initial ground stress field.The rationality of this calculation model is evaluated by the measured geostress data.Based on the ΔσH calculation model, a Δ(σH/σV) calculation model of the values range of the ratio of the horizontal and vertical geostresses (σH/σV) is deduced;this model is then used to provide a reasonable explanation of the σH/σV distribution of phenomenon in the surface and deep of earth''s crust is given from the perspective of rock mass stability.The coefficient of horizontal pressure (λ) is calculated via the lower ((σH/σV)min) and upper ((σH/σV)max) limits of σH/σV, which is given by the Δ(σH/σV), and comparative analysis of the calculated and measured values of λ is performed.Results show that the calculated and measured λ present consistent characteristics in a shallow rock mass but significant differences in a deep rock mass.Thus, the Δ(σH/σV) calculation model is applicable to λ calculations in shallow rock mass engineering.The calculated λ presents obvious nonlinear variation features along the depth (h) direction, and the functional relationship λ=ahb+1 between λ and h is given by setting up appropriate boundary conditions;this functional relationship is confirmed by curve fitting.The fitting results show a very high fitting correlation coefficient for λ=ahb+1, which means it can describe the functional relationship between λ and h well.This functional relationship can be used for initial geostress field evaluations and provides the necessary initial geostress field conditions for simulating deformation and failure of excavated rock masses.%在初始地应力场参数计算中引入岩体波速,通过基于岩体波速的Hoek-Brown准则建立初始地应力场中水平地应力σH的取值范围ΔσH计算模型,并通过实测地应力数据验证了ΔσH计算模型的合理性.在ΔσH计算模型的基础上,推导出了σH/σV(水平地应力/垂直地应力)的取值范围Δ(σH/σV)计算模型,并通过Δ(σH/σV)计算模型从岩体稳定性的角度对σH/σV在地壳表面和深部的分布现象进行合理解释.通过Δ(σH/σV)计算模型给出的σH/σV的取值下限(σH/σV)min和取值上限(σH/σV)max算出侧压系数λ,并给出了侧压系数λ与深度h之间的函数关系λ=ahb+1.
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