高放废物处置库新场和芨芨槽预选场址地壳稳定性研究

【作者】 云龙；

【导师】 王驹；

【作者基本信息】 核工业北京地质研究院 ， 矿产普查与勘探， 2014， 博士

【摘要】 目前国际上公认的、技术上可行的高放废物处置方法为深地质处置，即将废物固化体置于由工程屏障和天然屏障组成的“多重屏障体系”中，以达到与生物圈长期隔离的目的。在高放废物地质处置库的选址过程中，要考虑包括自然地理、水文地质条件及围岩性质等多种因素。当选址工作进入场址比选阶段后，预选场址的地壳稳定性成为影响处置库选址的关键因素之一。本文以新场和芨芨槽预选场址为主要研究区域，以上述预选场址附近及岩体内的断裂为主要研究对象，通过构造地貌调查，探槽开挖、加速器质谱14C测年、光释光测年（OSL）、电子自旋共振（ESR）测年等手段，给出以上预选场址附近及岩体内断裂的活动时代，进而评价新场和芨芨槽预选场址的地壳稳定性。主要取得以下认识：1、高放废物北山预选区位于整体稳定的阿拉善地块内。新场预选场址附近和岩体内部主要发育20条断裂，分为5组：（1）北西向的咸水井断裂系，位于新场岩体西北侧，多发育于花岗岩山丘间的沟谷、槽地内，为早、中更新世或前第四纪断裂；（2）近东西向的金庙沟断裂（F6），位于新场岩体北侧，断裂以左旋走滑为主，为前第四纪断裂；（3）北东向旧井断裂系，发育于新场西侧，以正走滑为主，其中旧井断裂为晚更新世晚期以来的活动断裂，但受其规模等因素的影响，对新场预选场址的影响较弱；（4）北东和北北东向的新场岩体断裂系，发育于新场岩体内，主要沿沟谷和槽地发育，以左旋走滑为主，为前第四纪断裂。（5）新场南侧的F95断裂，以左旋走滑为主，为早、中更新世断裂。2、芨芨槽预选场址附近和岩体内主要发育12条断裂，分为2组：（1）近东西的红旗山断裂（F1），位于芨芨槽岩体南侧，以右旋剪切为主，为前第四纪断裂；（2）北东向的芨芨槽岩体断裂系，发育于芨芨槽岩体内，以左旋走滑为主，为早、中更新世断裂。3、三危山断裂为阿尔金断裂带东北端的分支断裂之一，断裂沿一系列北东向的线性断层三角面分布，断裂的左旋位移速率为0.1～0.4mm/a。探槽揭露出3次古地震事件，分别发生在距今约5.6万年前、距今约4万年前和距今7.4～2.4ka，表明三危山断裂为全新世以来的活动断裂。4、旧井断裂在断层几何上呈复杂的张性“帚”状构造，断裂沿线性排列的断层三角面分布，断裂以正断左旋走滑为主，水平位移量为1.3～6.5m，多集中于3.0～4.0m的范围，垂直位移量约3.0m。探槽揭露出2次古地震事件，分布发生于距今7.6～7.8万年之间和距今约2.2万年，表明旧井断裂为晚更新世以来的活动断裂。5、参考相关规范，初步给出了高放废物地质处置库区域地壳稳定性分级标准，依据此标准，初步判定新场和芨芨槽预选场址处于地壳稳定区。更多还原

【Abstract】 Deep geological disposal of high-level radioactive waste is currently consideredas the most technically feasible method for the final safe isolation of high-levelradioactive waste from human environment. That is necessary to select a naturalgeological barrier and set multiple engineered barriers (multi-barrier system) in theunderground repository in order to achieve long-term or permanent isolation of HLWfrom human environment. In the site selection process of HLW waste disposalrepository, many factors should be considered which included natural andgeographical condition, hydro-geological condition, rock properties and so all, amongthem the crust stability is one of the key factors in the repository siting. In this paper,we choose Xingchang and Jijicao selection as a main research area, the faults whichdisgovered in the Xingchang and Jijicao selection and in their vicinity are consideredas the main study object. In order to evaluate the crust stability of Xingchang angJijicao selection, we use the geomorphology survey, trench excavation, AMS14Cdating, OSL dating (OSL), electron spin resonance (ESR) dating and other methods,to identify the activity age of those faults, and the main results obtained are asfollows:1. Beishan area is preselected place for high-level radioactive waste disposalrepository in the Alax stable Block. There are20faults in and near the Xingchangselection, which can divide into5groups:(1) Xian Shuijing faults system, which isnorth-west strike faults and in the northwest of the Xingchang selection. Those faultsare distributed in the valley or groove that between the granite hills, and their finalactivity age is early-middle Pleistocene or Pre-Quaternary;(2) Jin Miaogou fault (F6),which was west-east strike fault and in the north of the Xingchang selection. Thisfault is left-lateral strike-slip fault and its final activity age is Pre-Quaternary;(3)Jiujing faults system (F20), which are north-east strike fault and located in the west ofThe Xingchang selection. Those faults belong to the normal and left-lateral strike-slipfault. The Jiujing faults group is in the proximity of the Xingchang selection and itsfinal activity age is late Pleistocene, but it is limited by its scale and something else, the influence of these faults on Xingchang selection is weak;(4) The faults system islocated in the Xingchang rock mass is north-east or North north-east strike faults.Those faults are discovered in the valley or groove that formed between the granitehills, and their final activity age is Pre-Quaternary;(5) The F95fault, which occused inthe south of the Xingchang selection. This fault is left-lateral strike-slip fault and itsfinal activity age is early-middle Pleistocene.2. There are12faults in and near the Jijicao selection, which can divide into2groups:(1) Hong Qishan fault (F1), which is est-east strike fault and appears in thesouth of the Jijicao selection. This fault is in the left-lateral ductile shear zone and itsfinal activity age is Pre-Quaternary; the faults system is located in the Jijicao Rockmass is north-east strike faults. Those faults ars left-lateral strike-slip fault and theirfinal activity age is early-middle Pleistocene.3、The Sanweishan fault, which belongs to the Altyn Tagh fault, is one of thebranch faults in the north-east of Altyn Tagh Fault. The distribution of this fault is inthe form of a series of linear fault triangle that is north-east strike. The lest-lateralvelocity of the fault is between0.1and0.4mm/a. Three trenching has reveled3paleoseismic events that place took in56ka,40ka and between7.4and2.4ka beforepresent, which means the Sanweishan fault was a Holocene activity fault.4. The Jiujing faults group is in the form of complex extensional horsetailsplay structure in geometry. The distribution of this fault group is in the form of aseries of linear fault triangle. This faults group is normal and left-lateral strike. Thehorizontal displacement is1.3～6.5m, and most of them is between3.0to4.0m, andVertical displacement is around3m. The trenching has reveled2paleoseismic eventsthat was occurred in76～78ka and22ka, which means the Jiujing faults groupbelongs to the late Pleistocene activity fault5. Refer to relevant secifications, we give the reginal custsal stability preliminarystandard that for the geological dispoal of high-level radioactive waste repository, andaccording to this regulations, we initial consider that the Xingchang and Jijicaoselection is in the crust stable area.更多还原