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地应力是赋存于地壳岩土体中未受到工程扰动的天然应力,又称为原岩应力,其成因及其影响因素非常复杂,主要与历史上地球的各种构造运动有关。而准确的地应力测量计算及分析,对于工程结构稳定性设计及施工稳定和安全性分析极其重要。目前,三维地应力求解仍是基于“均质、连续、各向同性、线弹性”的理想岩性假设,而对于自然界普遍存在的非理想岩体,此种分析将产生较大误差。本文根据有限元原理分析了横观各向同性岩体岩层走向与钻孔夹角对于地应力计算造成的误差,岩层走向与钻孔夹角的变化对第三主应力大小影响最为明显,其中当倾角为90°时,误差最大(σ_1大小误差为2.68%,σ_2大小误差为1.44%,σ_3大小误差为94.91%),其次对第一主应力方位角与第三主应力倾角影响也较为明显。
Geostress is the natural stress, also known as the original rock stress, existing in the crust and rock mass without disturbing the engineering. Its origin and its influencing factors are very complicated, and are mainly related to the historical tectonic movements of the earth. Accurate calculation and analysis of geodetic stress measurement is extremely important for the stability design and construction stability and safety analysis of engineering structures. At present, the three-dimensional geostress solution is still based on the ideal lithology assumption of “homogeneous, continuous, isotropic, linear elasticity ”, and this analysis will produce a large error for the non-ideal rock mass ubiquitous in nature. Based on the finite element method, the error of formation direction and angle of drilling is analyzed for the calculation of in-situ stress. The change of rock orientation and drilling angle has the most obvious influence on the third principal stress. When When the inclination angle is 90 °, the error is the largest (the error of σ_1 is 2.68%, the error of σ_2 is 1.44%, and the error of σ_3 is 94.91%). Secondly, the influence of the first principal stress azimuth and the third principal stress dip is obvious.