某场地红层岩溶发育特征及工程影响研究

发布时间：2018-04-26 14:10

本文选题：红层岩溶 + 发育特征　；参考：《成都理工大学》2015年硕士论文

【摘要】：四川盆地红层岩溶广泛发育。本文根据四川夹江某场地的工程、水文地质勘察中所遇到的红层岩溶(溶蚀孔洞)问题,研究其发育特征及对工程建设的影响。论文在对研究区自然地理、地层岩性、地质构造及水文地质情况的分析基础上展开。通过对岩石学性质、形态大小、填充物质的分析；对岩溶的空间分布规律的统计,研究了岩溶发育特征；对含石膏盐岩石的溶蚀速率实验分析,研究了岩溶溶蚀机理：通过水文地质特征分析,研究了岩溶的形成作用特点；最后结合地下水渗流数值模拟,反演论证研究场区岩溶发育、溶蚀及水文地质条件,得出了岩溶发育的工程影响。本次研究主要取得了以下几点认识：(1)研究区位于扬子准地台四川台坳川西台陷南部的白垩系灌口组红层地区,区域地质构造走向以北东向构造体系为主,南安向斜和F2逆掩断层是主要的地质构造。区域地形以构造剥蚀为主,属低山-丘陵地貌。在青衣江两岸木城、南安附近,以河流堆积的一阶地为主。早白垩系后期的燕山运动时期形成的晚白垩系灌口组(K2g)地层为一套明显的咸湖红色河流相粉砂质泥岩与泥质粉砂岩色地层,该地层中发育有大量的石膏盐。浅层风化裂隙水是区域内主要的地下水类型。场区西南侧接受大气降雨,中部是地下水的渗流区,向大堰溪排泄。区内渗流作用较强烈。地表水体不发育,大气降雨为场区内地下水主要补给源。区内水化学阳离子以Ca2+离子为主,阴离子以HCO3-离子为主。(2)研究区内红层岩溶表现形式主要有石膏斑点、溶蚀孔洞(溶孔)和溶洞。溶孔是区内最重要最典型的岩溶形态,溶孔填充类型有硐壁结晶类填充、泥质类填充、碎石类填充。因伴生发育条件的不同,溶孔又分为原生溶孔和构造溶孔。场区岩溶发育形态以地下形态为主,有石膏斑点、溶孔、溶洞。依据发育类型、密集程度、危害程度,岩溶平面分布可分为三个区域。作为岩溶最主要物质的石膏盐,垂向分布方式有互层状和脉冲状。溶孔垂向分布有普遍性和集中性特征。初步分析场区岩溶发育形态和分布特征与地质构造和地下水渗流相关。但总体来说,发育程度有限。(3)石膏盐(石膏、芒硝、钙芒硝)是场区溶孔形成的重要物质,对岩溶容蚀机理的研究,即是对含石膏盐岩岩石的溶蚀作用影响分析。岩石学成分分析方法有薄片鉴定法和化学分析法,初步分析认为,粉砂质泥岩和泥岩是场区内含石膏盐主要岩石,二者岩性的差异不是溶孔形成的主要因素。溶孔的发育形态与石膏盐的溶蚀速率和溶蚀方式有关,根据溶蚀速率实验设计的两组实验方案(静水条件和流水条件,因本实验试块等因素影响,流水实验结果参考各相关资料)得出的实验数据,对比分析碱浓度、以及重量与溶蚀物质含量的关系,以此反映岩石的溶蚀特性。实验结果认为,地下水渗流在岩溶形成过程中起主要作用,含石膏盐岩层溶蚀同时存在化学作用与物理作用两种过程,二者相互影响。地下水渗流是岩体溶蚀的主要作用,其形成作用是对可溶岩的溶蚀结果和搬运等潜蚀作用结果。(4)研究区岩溶发育导致岩体中除了常规构造风化作用产生的裂隙渗流通道,还有因溶孔形成的地下水渗流通道。压水试验是获取岩层水文地质参数的有效途径。针对现今环境中溶蚀裂隙发育情况下,运用模型反演方法,通过对初始水位和各参数的校核,对场地地下水初始水流场进行拟合。从模型方面论证场地红层岩溶发育特征及溶蚀机理,检验压水试验的实际效果。除此之外,场地的三维数值模拟,还可对今后的防渗处理提供指导。
[Abstract]:The red layer karst of the Sichuan basin is widely developed. Based on the engineering of a site in Jiajiang, Sichuan, the problems of the red layer karst (dissolution hole) encountered in the hydrogeological survey are studied, and the characteristics of the development and the influence on the construction are studied. Through the analysis of the properties of petrology, the size and the filling material, the characteristics of karst development are studied by the statistics of the spatial distribution law of karst, and the dissolution rate of gypsum with salt rock is analyzed, and the karst erosion mechanism is studied. The formation function of karst is studied through the analysis of hydrogeological characteristics; finally, the combination of the karst is studied. The numerical simulation of water seepage is used to demonstrate the karst development, erosion and hydrogeological conditions in the study field, and the engineering influence of karst development is obtained. This study mainly obtains the following points: (1) the study area is located in the red layer area of the Cretaceous chalkiness formation in the south of the Sichuan Taiwan depression of the Yangzi quasi platform, and the regional geological structure is heading for the area. The Nanan syncline and the F2 overthrust fault are the main geological structures. The regional topography is dominated by structural denudation and is a Low Mountain hilly landform. In the wooden city on both sides of the Qingyi River and near Nanan, the main terrace is a terrace accumulated in the river. The late Cretaceous group (K2g) formation formed in the late Yanshan movement period of the early Cretaceous system is one of the first strata. A large amount of gypsum salt is developed in the red river facies silty mudstone and silty sandstone of salty lake. The shallow weathered fissure water is the main type of groundwater in the region. The southwest side of the field receives atmospheric rainfall, the middle part is the seepage area of the groundwater and excrete to the great weir stream. The seepage effect in the area is strong. The surface water body is stronger. No development, atmospheric rainfall is the main source of groundwater recharge in the field area. The main water chemical cations in the area are Ca2+ ions, and the main anions are HCO3- ions. (2) the main forms of red layer karst in the study area are gypsum spots, dissolution holes (dissolved pores) and karst caves. Wall crystal filling, muddy filling and gravel packing. Because of the difference of the associated development conditions, the dissolved pores are divided into primary dissolving holes and structural dissolving holes. The karst development form in the field area is mainly underground, with gypsum spots, dissolving holes and karst caves. According to the development type, the degree of density, the degree of hazard, and the karst plane distribution can be divided into three regions. The vertical distribution patterns of the main material are interbedded and pulsed. The vertical distribution of the dissolved pores is universal and concentrated. The preliminary analysis of the morphology and distribution of karst development in the field is related to the geological structure and groundwater seepage. But in general, the development degree is limited. (3) the gypsum salt (gypsum, mirabilite, Glauber's Glauber's Glauber's salt) is a field dissolution hole. The important substances formed in the study of the mechanism of karst erosion are the analysis of the effect of the dissolution of gypsum bearing rock and rock. The analysis methods of petrological composition are thin slice identification and chemical analysis. The preliminary analysis shows that the silty mudstone and mudstone are the main rock of gypsum salt in the field, and the difference of the two lithology is not the formation of dissolved pores. The main factors. The development form of the dissolved pore is related to the dissolution rate and dissolution mode of gypsum salt. According to the two experimental schemes designed by the experiment of the dissolution rate (hydrostatic and flowing water conditions, the experiment block and other factors, the results of the water experiment refer to the experimental data), the alkali concentration, the weight and dissolution are compared and analyzed. The relationship between the content of the material is reflected to reflect the dissolution characteristics of the rock. The experimental results show that the groundwater seepage plays a major role in the process of karst formation, and there are two processes, including chemical and physical effects, including the chemical and physical effects of the gypsum salt rock formation. The groundwater seepage is the main effect of the rock mass dissolution. The result of dissolution of karst rock and the result of submersible erosion such as handling. (4) the karst development in the study area leads to the seepage passage of the fracture in the rock mass except the conventional tectonic weathering, and the seepage channel formed by the dissolved pore. The pressure water test is an effective way to obtain the hydrogeological parameters of the rock strata. Under the condition of the model inversion method, the initial water flow field in the ground water is fitted by checking the initial water level and the parameters, and the characteristics of the karst development and the dissolution mechanism of the ground red layer are demonstrated and the actual effect of the water pressure test is tested. Besides, the three-dimensional numerical simulation of the site can also provide the seepage prevention treatment in the future. Guidance.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.25

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