基于钻孔应力、应变连续实测资料研究新疆相对应力场

STUDY OF XINJIANG RELATIVE STRESS FIELD BASED ON CONTINUOUS BOREHOLE STRESS AND STRAIN DATA

利用1985年以来新疆地区钻孔应力、应变连续观测资料研究相对应力场,研究结果表明,新疆地区相对应力场的主压应力方向近NS,呈现区域性分布特征。西昆仑中、西段近NS向,西昆仑东段、北天山、塔里木盆地西北缘为NNE向;南天山西部为NW向,南天山东部为NE向。新疆的压应力作用极强,剪应力作用较大,张应力作用较弱。应力量值有西大东小、南强北弱的特点;帕米尔弧与天山交汇的喀什地区主压应力值、剪应力值最大,北天山中部的石河子的主张应力值最大,乌鲁木齐的应力值最小;应力变化量值差别大,且在空间上呈现不均匀性。相对应力场的主压应力方向与区域构造线走向、山脉延展方向交角较大,表明新疆的山脉及构造主要受挤压应力的作用。

The relative stress field was analyzed through a series of continuous observed borehole stress-strain data in Xinjiang region. The results show that the direction of principal compression in terms of relative field is orientated mainly in NS direction but has the feature of regional distribution. In the middle and western sections of the West Kunlun mountain it shows in the NS direction, while in the East Kunlun mountain it exhibits in the NNE direction. In the North Tianshan mountains and the Tarim Basin it also indicates in the NNE direction. In the west part of South Tianshan it ordinates in the NW direction; and while in the east part of south Tianshan mountains it is in the NE direction. The results further indicate that both the compression and shearing stresses are large but weak for tensile stress. The magnitude of stress tends to reduce from the west to the east and weak from the south to the north. For the magnitude of both the principal compression and the shearing stress the largest ones are dominant in the Kashi region, where the Pamir arc and the Tianshan mountain is intersected. For the magnitude of the principal tensile stress the largest one is observed in Shihezi region of the North Tianshan and the smallest one is exhibited in Urumqi region. Meanwhile, the difference of the stress variation is large and shows a nonuniform distribution. The angle between the direction of principal compression and the regional tectonic trend and the mountain extended line is large, which indicates that the tectonic and mountain in Xinjiang region is subjected to the action of compression force, which is perpendicular to the above tectonic lines.