摘要
目前,在高地温高地应力环境下,未见报道在反演过程中考虑地温,从而导致反演得到的初始地应力场与实际不符。为使反演得到的初始地应力场更加符合实际,首次提出考虑地温的岩体初始地应力场反演思路。在高地温高地应力环境下,岩体初始地应力场可近似由重力应力场、构造应力场及温度应力场组成。而岩体温度应力场可结合地温梯度法并依据岩体热应力公式近似得到,再通过叠加原理将温度应力场叠加到重力及构造应力场中即可得到与高地温相符的岩体初始地应力场。在水压致裂法测得的3个主应力中,垂直应力是通过上覆岩层的实测密度计算而来,即垂直应力不包含温度应力,故在高地温高地应力环境下,若不考虑地温,则采用水压致裂法测得的应力反演岩体初始地应力场将造成严重错误。例如在桑珠岭隧址区,岩体的温度应力大约为自重应力的8/13,即在反演过程中如果不考虑地温,则反演得到的岩体初始地应力场将缺失占重力应力场8/13的竖向温度应力场,且考虑地温的反演结果较不考虑地温更好。
At present,under the environment of high geo-temperature and high geostress,it is not reported that geo-temperature is considered during geostress inversion,which causes that the initial geostress field obtained by inversion is not consistent with the actual geostress field of rock masses. In order to overcome the shortcoming,a workflow of inversion for the initial geostress field of rock masses considering geo-temperature is proposed. Under the environment of high geo-temperature and high geo-stress,the initial geostress field of rock masses can be approximately composed of gravitational,tectonic and thermal stress fields. The thermal stress field of rock masses can be approximately obtained by the geothermal gradient method and the thermal-stress formula of rock masses. Superposing the thermal stress field of rock masses into the gravitational and tectonic stress fields of rock masses can obtain the initial geostress field consistent reflecting the impact of high geo-temperature. Due to that the vertical stress is calculated by the density of overlying strata without considering the thermal stress,inverting the initial geostress field of rock masses based on the stresses measured by hydraulic fracturing will cause serious errors under the environment of high geo-temperature and high geostress. At the area of the Sangzhuling tunnel,for example,the thermal stress is about 8/13 of the gravitational stress. Comparisons between the inversion results and the measuring data of Sangzhuling tunnel show that the inversion results considering geo-temperature are better than those without considering geo-temperature.
作者
蒙伟
何川
张钧博
周子寒
汪波
MENG Wei;HE Chuan;ZHANG Junbo;ZHOU Zihan;WANG Bo(Key Laboratory of Transportation Tunnel Engineering of Ministry of Education,Southwest Jiaotong University,Sichuan,Chengdu 610031,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2020年第4期749-760,共12页
Chinese Journal of Rock Mechanics and Engineering
基金
高铁联合基金重点项目(U1734205)
国家重点研发计划项目(2016YFC0802201)
西南交通大学博士研究生创新基金项目(D-CX201802)。
关键词
岩石力学
高地温
高地应力
初始地应力场
反演
岩体
rock mechanics
high geo-temperature
high geostress
initial geostress field
inversion
rock mass
