基于岩体波速和Hoek-Brown准则的初始地应力场参数计算模型研究

Study on Parameter Calculation Model of Initial Ground Stress Fields Based on the Wave Velocity of a Rock Mass and the Hoek-Brown Criterion

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σ_H的取值范围Δ_(σ_H)计算模型,并通过实测地应力数据验证了Δ_(σ_H)计算模型的合理性。在Δ_(σ_H)计算模型的基础上,推导出了σ_H/σ_V(水平地应力/垂直地应力)的取值范围Δ(σ_H/σ_V)计算模型,并通过Δ(σ_H/σ_V)计算模型从岩体稳定性的角度对σ_H/σ_V在地壳表面和深部的分布现象进行合理解释。通过Δ(σ_H/σ_V)计算模型给出的σ_H/σ_V的取值下限(σ_H/σ_V)_(min)和取值上限(σ_H/σ_V)_(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=ah^b+1。

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 theΔ（σH）calculation model,aΔ（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/σVdistribution 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 ofσH/σV,which is given by theΔ（σH/σV）,and comparative analysis of the calculated and measured values ofλis performed.Results show that the calculated and measuredλ present consistent characteristics in a shallow rock mass but significant differences in a deep rock mass.Thus,theΔ（σH/σV）calculation model is applicable toλcalculations in shallow rock mass engineering.The calculatedλpresents obvious nonlinear variation features along the depth（h）direction,and the functional relationshipλ=ahb＋1betweenλand his 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 forλ=ah^b＋1,which means it can describe the functional relationship betweenλand 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.