【摘要】 针对浅表高水平地应力和高侧压系数常出现在岩浆岩和变质岩中的现象,以广泛分布的形成于地下深处的花岗岩为例,指出构造隆升作用下,花岗岩从形成时位于深部到现在处于剥蚀卸荷过程中而常出露地表,无论是采用静水压力还是弹性体假设,都可得出其侧压系数明显变大的结论。对254组花岗岩地应力现场实测结果统计,得到了侧压系数拟合公式更符合花岗岩实测结果分布情况。由广义虎克定律出发,结合垂向卸荷后地下某处水平应变为0的假设,推导出花岗岩体剥蚀厚度计算公式,其结果接近目前为止认识到的剥蚀厚度的上限值。初步工程资料分析对比发现,大亚湾燕山期花岗岩地质分析剥蚀厚度为1 300 m,计算结果介于1 500～3 000 m之间;三峡工程船闸区花岗岩剥蚀厚度为1 700～3 200 m,与裂变径迹法测试结果比较吻合。结果说明,花岗岩体剥蚀厚度相对于现在一般工程埋深是比较大的。更多还原

【Abstract】 It was found that in shallow depth in magma and metamorphic rocks,the value of lateral coefficient is higher relative to sedimentary rocks.Taking the granitic rocks for examples,which is widely exposed in ground surface and regarded as originally intruded to form a dome at larger depth,this paper presents the computation result of denudation thickness.The method is started from two kinds of suppositions for representation of dominant stress in 3D in large depth before obvious denudation.One is hydrostatic head,another is Hooke’s law and then the horizontal strain is zero during denudation process.The lateral coefficient formula is used to infer the denudation thickness,which is commonly larger for both of the two suppositions.Statistic results of in-situ stress data of 254 groups in granitic rocks are of a new fitting formula to the average counterparts.From the 2nd supposition,it is inferred the denudation thickness,which is seemed to closed to the updated high limitary values of denudation thickness whether from geological judgment or fission-track data of apatite.To check the feasibility of this method,two case histories are presented.The denudation thickness as Daya Bay is between 1 500 m and 3 000 m,closed to 1300m from geological judgment.The denudation thickness at the shiplock of the Three Gorges Project is 1 700-3 200 m,similar to that test result of fission track analysis.The results further prove that the denudation thickness is relatively larger than most of the buried depth of underground rock engineering.更多还原