The essential cause inducing weather and unloading is distict difference between epigenetic - surface and deep condition . firstly , the dissertation introduces the background conditions that are the base of damsite granite rockmass weathring and unloading ; secondly , the mechanism of the rockmass weathering and unloading is probed into ; thirdly , different degree weathered zones and load - off zones are compartmentalized . tastly , right rockmass which meet the dambase demand is choosed . above - mentioned is the dissertation " s technical course which is clearly from base research to application research . 本文以黄河拉西瓦水电站坝基花岗岩体为研究对象，从风化、卸荷发生的根本原因?岩体在地表与深部存在巨大环境差异为契入点，制定了从背景条件?机理研究?风化、卸荷分带?坝基可利用岩体选取这样一条从基础研究到应用研究的较为明晰的技术路线。
In the area of the left bank , rock body is mainly composed of permian period - triassic period granite and triassic period siltstones and mudstones ( t2m ) . moreover , the rock body has been more faulted , such as f1 f3 f9 and so on . in addition , there also exist a lot of joints and form complex rock mass structure 工程区主要出露二迭纪三迭纪花岗岩体( _ 4 ~ 3 _ 5 ~ 1 )和三迭系中统忙怀组下段沉积岩( t _ ( 2m ) ~ 1 ) ，发育有工程区规模最大的f _ 1和f _ 3断层，以及其它断层和大量的各类断续延伸的裂隙，岩体结构较为复杂。
Detail mapping shows that the yagan mcc consists of crystallized metamorphic core ( low plate ) , detachment zone and upper plate . the metamorphic core consists of can be further subdivided into two level parts low - level high metamorphic and upper - level shallow metamorphic structural slice and between them there exists a ductile shear zone . thus the whole texture of the mcc is characterized by " three layers and tow zones " this reveals a process of extensional uplift of poly - level slices by poly ductile shear zones , a characteristics of poly - level extensional structural systems . the deformational environments change vertically in a sequence of high amphibolite facies 亚干变质核杂岩由下盘结晶岩系变质核、拆离带和上盘岩系构成，其中，变质核由四个单位及许多花岗岩体(脉)组成，可进一步分为中深和中浅变质两个构造单位(岩片) ，之间发育次级韧性拆离带(花岗质糜棱岩带) ，加上上盘总体构成“三层两带”的结构特点。
