唐山地区深部应力测量
DEEP STRESS MEASUPEMENTS IN TANGSHAN AREA
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摘要: 在唐山东约20公里的东矿区黄坨苗圃356米深钻孔中,在300米以上深度成功地进行了11次水压致裂应力测量,取得了主应力大小及其方向随深度变化的资科。测量结果表明,现在唐山地区的应力水平很低,在接近300米的深度上最大水平主应力仅7.8兆帕,最大水平剪应力值也仅1兆帕。最大主应力方向在180米以上变化较大,180米以下的三次测量结果一致性很好,最大主应力方向为北81°西到北86°西,与华北地区应力测量的总体方向是一致的。文中还将水压致裂应力测量的结果与应力解除与用声发射凯塞效应法测得的结果作了对比。Abstract: 11 hydraulic fracturing in-situ stress measurements have been successfully performed in upper 300m deep borehole at Huangtuo nursery, East Mine Region, 20Km east of Tangshan city.Variations of magnitude and direction of in-situ stresses with depth were obtained.The results indicate that the horizontal principal stresses are very low presently in Tangshan area, the maximum horizontal principal stress is only 7.8 Mpa near depth of 300m, and the maximum horizontal shear stress is 1 Mpa.The direction of maximum stress varies apparently in upper 180m depth, the results of three measurements are considerably consistent below the depth of 180m, the directions of the maximum principal stresses are N81°W to N86°W and consist with the general direction of in-situ stress measurements in North China.This paper also presents comparison of hydrofracturing stress measurements with the results obtained using overcoring and acoustic emission Kaiser effect methodes.