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紧密的粉细砂层,探头贯入阳力极高,已不能用低应力水平条件下的力学指标来研究紧砂触探机理分析。本文考虑到砂性介质在高应力状态下特殊的剪切和压缩特性,采用非线性应力——应变——强度本构关系,籍助于能量平衡原理和无限土体中孔腔扩张理论,并用试算法和有限差分法进行分析,从而作出对砂性地层的工程评价。实用上可根据径向应力随离孔心距离呈指数关系衰减的特点采用一些经验方程简化分析。
With the tight fine sand layer, the penetration force of the probe is extremely high, and the mechanical analysis of the tight sand penetration cannot be studied using the mechanical parameters under low stress levels. This paper considers the special shear and compression characteristics of sand medium under high stress, adopts the nonlinear stress-strain-strength constitutive relation, and benefits from the principle of energy balance and the theory of pore expansion in infinite soil. The trial algorithm and the finite difference method were analyzed to make an engineering evaluation of the sand formation. Practically, some empirical equations can be used to simplify the analysis according to the characteristics that the radial stress decays exponentially with the distance from the hole center.