摘要
为研究V型河谷区岩体应力的大小、方向及其分布,采用水压致裂法对河床和山体内的平面和三维地应力进行现场测量。实测最大水平主应力方向为NW40°～60°,最大水平主应力值最高近40MPa,最小水平主应力值为20MPa;在河床谷底浅部80m以上,受河谷卸荷影响地应力有所释放,形成卸荷带;孔深90～130m产生应力集中,形成V型峡谷典型的“应力包”分布特征;在山体内PD27#平硐不同硐深处的3个测点进行三维地应力测量。测量结果表明:三维主应力值随硐深的增加而增大,从1#～3#测点测得的最大主应力和最小主应力的数值增加近1倍;3个测点主应力的方位和倾向大体一致,随硐深的增加,最大主应力倾角逐渐变陡,反映出重力的贡献越为显著。对原地应力实测结果进行解析,得到隧道横截面的最大主压应力和最小主压应力及相关的应力参量,结合岩爆判据对隧道发生岩爆的可能性进行分析,隧道横截面内最大差应力的大小是控制岩爆发生的主要因素。
To study the distribution,values and directions of rock stressest,he plane and three-dimensional stresses in the riverbed and mountain massif are measured in field by hydraulic fracturing method in V-shaped river valley.The direction of the measured maximum horizontal principal stress is NW40°–60°,the value of the maximum horizontal principal stress is near to 40 MPa,and the minimum horizontal principal stress is about 20 MPa.The in-situ stress has been released as river valley unloaded and unloaded zone has been formed above 80 m around river valley shallow depth.The stresses concentration happens in the depth of 90–130 m;and the typical “stresses fold”of V-shaped river valley has been formed.Three-dimensional in-situ stress measurement is conducted at three points with different depths in cavity PD27.The results indicate that the three-dimensional principal stress increases with the depth increasing.The maximum and minimum principal stresses are double of their values from the first point to the third one.The orientation and trend of the principal stresses in three points are consistent.With the increase of the cavity depth,the inclination of the maximum principal stress becomes steeper gradually,which indicates that the contribution of the gravity is more dominant.The maximum and minimum principal compressive stresses in the tunnel cross section are obtained by stress analysis.The possibility of rockburst is analyzed combining the rockburst criterion.Analysis shows that the rockburst is controlled by the maximum difference stress in the tunnel cross section.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2006年第z1期3069-3073,共5页
Chinese Journal of Rock Mechanics and Engineering
关键词
岩土力学
水压致裂
平面应力
三维应力
卸荷带
应力集中
岩爆
rock and soil mechanics
hydraulic fracturing
plane stresst
hree-dimensional stress
unloaded zone
stress concentration
rockburst
