The Study Of Geostress Characteristics And Engineering Areas Geostress Inversion In The Southwest Region

Crustal stress not only has a controlling power over the stability of the specific area but also is the culprit of the deformation and destruction of rock mass engineering.Along with the unceasing development of Western region,a new round of infrastructure construction,like,tunnels,water conservancy and hydropower,and mine develops towards the direction of length,hugeness and deep burial.The emergence of deep burial makes apparent the influence of crustal stress,especially in southwestern area due to its unique geological structure,preference for high altitude and super unearth buried rock masses engineering.That has become the fundamental factor threatening safety of engineering.Therefore,it is imperative to make a relevant study.Guided by the theory of statistical regression theory,this paper is trying to find out the feature of crustal stress in southwest region with the help of MATLAB software and the analysis of related data from engineering construction,scientific study,and disaster warning.What's more,this thesis is aimed for figuring out the rule of geostatic stress of four province in this area and then evaluates the effect of lithology over ground stress.Materials relevant to lithologic character are classified into three types,which is going to be carefully studied to make it clear which direction bear the primary stress of geostress through repeated practical test.At last,draw a rose diagram of stress orientation to make sure the principal geostresses involved.In conclusion,firstly,the variation rule with increasing depth of ?H??h??v in southwestern area is the same as that in mainland China.However,the gradient value of the maximum horizontal principal stress is above while the gradient value of the maximum vertical principal stress is below than that in mainland of china.The conversion level of crustal stress here can reach 5500 meters,with high horizontal stress value and gradient value.Secondly,taking rule of ground stress and geological condition of all research areas into consideration,this paper founds out that the sequence of tectonic movement,from strong to weak,is Tibet,Sichuan,Yunnan and Guizhou accordingly.Thirdly,the trend line of Kav varying with depth outside and inside envelope curve is within that of mainland.What's more,except Guizhou province,the kav value of the rest parts concerned converges to around 1.Fourthly,there exist some differences with regard to the distributing rule of ground stress in three types of rock there.For magmatic rock,kav value converges to 1.42 with increasing depth.For sedimentary rock and metamorphic rock,they share the same changing rule and kav value which,however,varies differently in shallow layer.Fifthly,the orientation preferred of maximum principal stress in study area is NE-SW and NWW-SEE,which is identical to direction of interaction between plates.For Sichuan province,influenced by fault zone,the horizontal orientation preferred of the maximum principal stress is NE-SW and NWW-SEE,but the direction,NWW-SEE,plays a dominant role.As to Yunnan province,the horizontal orientation preferred of the maximum principal stress is NE-SW.Because of extrusion of Indian Ocean plate from the north and the south,the horizontal orientation preferred of the maximum principal stress in Tibet mainly is NE-SW and NWW-SEE,though complex distribution.The last,in guizhou province,the horizontal orientation preferred of the maximum principal stress is NWW-SEE.Finally,based on the crustal stress of in site measurement and multiple linear regression calculated by rock engineering software(Midas/GTS),inversion analysis on geostress in Galongla Tunnel obtained a satisfactory result.And then,a systematic research on stress field distributing rule there was carried out.Naturally,some constructive conclusion has been drawn to offer assistance to the study of rock stability of surrounding tunnel,tunnel construction,structural support and selection of design parameters.