薄层灰岩浅部岩溶发育特征及分布模型
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摘要
碳酸盐岩往往含有较多泥质夹层,多发育浅部岩溶裂隙,影响工程基础稳定性。文章依托广西合山市溯河矿区某道路浅部岩溶调查成果,分析了薄层灰岩岩溶宏观形态和垂直分布特征,按照溶蚀程度将其分为碎屑残留带、表层岩溶带和下部包气带;通过室内溶蚀试验,分析了矿物组成、CO_2及水动力条件影响下的溶蚀规律;对比分析了薄层和厚层岩溶发育特征。结果表明:(1)薄层灰岩浅部岩溶发育程度与微地貌有关,通常在山谷和地下水强径流带溶蚀作用更为强烈;(2)薄层灰岩溶蚀优先开始于方解石,在岩石表面形成溶孔、粗糙程度增加,提供了侵蚀性溶液流动通道;(3)薄层灰岩岩溶较厚层灰岩岩溶规模小,分布较为均匀,由地表土体渗入地下岩体的地下水含有较多侵蚀性CO_2水溶液,会促进岩溶作用的进行;(4)薄层灰岩浅部岩溶发育分布模型为:发育均匀的微小溶蚀裂隙在溶蚀下渗过程中遇到软弱夹层时会沿水平向扩展并随进一步溶蚀作用被充填,垂向深部发展时溶蚀作用逐步消散。
Thin-layer carbonate rocks often contain more argillaceous interlayers,and more shallow karst fissures were formed,which may affect the stability of engineering foundation. However,there are few studies on the characteristics and occurrence of karst development in thin-layer limestones,which cannot effectively guide the exploration and design of engineering activities. In order to explore the characteristics of shallow karst development in thin limestones,based on the results of shallow karst investigation on a road in the Heihe mining area near the city of Heshan in Guangxi,the macroscopic and vertical distribution characteristics of thin layer limestone karst are analyzed. According to the degree of dissolution,it is divided into the clastic residual zone,surface karst zone and lower aeration zone. The dissolution process under the influence of mineral composition,CO_2 and hydrodynamic conditions is analyzed by the indoor dissolution test. The thinlayer and thick-layer karst development characteristics are compared and analyzed. The results show that( 1)the degree of karst development in the shallow layer of limestone is related to the micro-geomorphology,which is usually more intense in the valley and strong groundwater runoff zone.( 2) The karst erosion of thin limestone begins preferentially with calcite,forming karst holes and increasing roughness on the surface of rock,which provides corrosive solution flow channels.( 3) The karst of thin limestones is smaller in scale and more uniform in distribution,and the groundwater infiltrated into underground rock mass by surface soil contains more erosive CO_2 aqueous solution,which will promote the development of karstification.( 4) The evenly developed micro-cavitation cracks will expand horizontally in the process of dissolution and infiltration,and will be filled with further dissolution. The dissolution will gradually dissipate in the vertical deep development. Understanding the karst development characteristics and distribution model of shallow limestone in shallow rocks is of a guiding value for the difference in the accuracy of engineering survey work and the selection of basic engineering for the same type of karst site in different regions.
Thin-layer carbonate rocks often contain more argillaceous interlayers,and more shallow karst fissures were formed,which may affect the stability of engineering foundation. However,there are few studies on the characteristics and occurrence of karst development in thin-layer limestones,which cannot effectively guide the exploration and design of engineering activities. In order to explore the characteristics of shallow karst development in thin limestones,based on the results of shallow karst investigation on a road in the Heihe mining area near the city of Heshan in Guangxi,the macroscopic and vertical distribution characteristics of thin layer limestone karst are analyzed. According to the degree of dissolution,it is divided into the clastic residual zone,surface karst zone and lower aeration zone. The dissolution process under the influence of mineral composition,CO_2 and hydrodynamic conditions is analyzed by the indoor dissolution test. The thinlayer and thick-layer karst development characteristics are compared and analyzed. The results show that( 1)the degree of karst development in the shallow layer of limestone is related to the micro-geomorphology,which is usually more intense in the valley and strong groundwater runoff zone.( 2) The karst erosion of thin limestone begins preferentially with calcite,forming karst holes and increasing roughness on the surface of rock,which provides corrosive solution flow channels.( 3) The karst of thin limestones is smaller in scale and more uniform in distribution,and the groundwater infiltrated into underground rock mass by surface soil contains more erosive CO_2 aqueous solution,which will promote the development of karstification.( 4) The evenly developed micro-cavitation cracks will expand horizontally in the process of dissolution and infiltration,and will be filled with further dissolution. The dissolution will gradually dissipate in the vertical deep development. Understanding the karst development characteristics and distribution model of shallow limestone in shallow rocks is of a guiding value for the difference in the accuracy of engineering survey work and the selection of basic engineering for the same type of karst site in different regions.
引文
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[8] WANG T J,JIN L S,LI Z K,et al. Modeling study on acid rain and recommended emission control strategies in China[J]. Atmospheric Environment,2000,34:4467-4477.
[9] BERNER R A. Rate control of mineral dissolution under earth surface conditions[J]. American Journal of Science,1978(9):1235-1252.
[10]张傲,方云,陈建平,等.凝结水对碳酸盐岩溶蚀实验及数值模拟分析[J].岩石力学与工程学报,2014,33(增刊2):3648-3656.[ZHANG A,FANG Y,CHEN J P,et al. Experimental and numerical simulation analysis of carbonate rock dissolution by condensate[J]. Chinese Journal of Rock Mechanics and Engineering,2014,33(Sup2):3648-3656.(in Chinese)]
[11]彭军,王雪龙,韩浩东,等.塔里木盆地寒武系碳酸盐岩溶蚀作用机理模拟实验[J].石油勘探与开发,2018,45(3):415-425.[PENG J,WANG X L, HAN H D, et al. Simulation experiment of dissolution mechanism of Cambrian carbonate rocks in Tarim Basin[J]. Petroleum Exploration and Development, 2018,45(3):415-425.(in Chinese)]
[12]朱立军,李景阳.岩溶环境中岩—土界面方解石的表面化学特征及其反应机理[J].中国岩溶,1997,16(1):20-24.[ZHU L J,LI J Y. Surface chemical characteristics and reaction mechanism of calcite at rock-soil interface in karst environment[J].Carsologica Sinica,1997,16(1):20-24.(in Chinese)]
[13] SUCHET P A, PROBEST J L. Modeling of atmospheric CO2consumption by chemical weathering of rock. Application to the Geronne, Congo and Amazon Basiona s[J]. Chemical Geology,1993,107(3/4):205-210.
[14] YUAN Daoxian. The carbon cycle in karst Z[J].Geomorph N F,1997,108:91-102.
[2]缪世贤,黄敬军,武鑫,等.徐州岩溶地质调查及其发育特征分析[J].水文地质工程地质,2017,44(2):172-177.[MIU S X,HUANG J J,WU X,et al. Analysis of karst geological survey and development characteristics in Xuzhou[J].Hydrogeology&Engineering Geology,2017,44(2):172-177.(in Chinese)]
[3]王涛,李强,王增银.碳酸盐岩微生物溶蚀作用特征及意义[J].水文地质工程地质,2007,34(3):6-9.[WANG T,LI Q,WANG Z Y. Characteristics and significance of microbial dissolution of carbonate rocks[J]. Hydrogeology&Engineering Geology,2007,34(3):6-9.(in Chinese)]
[4]周冰,刘立,金之钧,等.泥岩盖层的溶蚀作用机理实验—不同p H值盐水中溶蚀速率变化规律[J].石油学报,2017,38(8):916-924.[ZHOU B,LIU L,JIN Z J,et al. Experimental study on dissolution mechanism of mudstone caprock—change law of dissolution rate in brine with different p H values[J].Acta Petrolei Sinica,2017,38(8):916-924.(in Chinese)]
[5]计顺顺,刘建刚,吴悦,等.岩溶管道和溶蚀裂隙示踪曲线特征室内实验对比研究[J].勘察科学技术,2017(4):11-14.[JI S S,LIU J G,WU Y,et al. Comparative study of indoor experiments of karst pipeline and dissolution crack trace characteristics[J]. Prospecting Science and Technology,2017(4):11-14.(in Chinese)]
[6]王中美,杨根兰,胡良博.贵州碳酸盐岩相与岩溶地下水赋水条件关系研究[J].水文地质工程地质,2016,43(1):6-11.[WANG Z M,YANG G L,HU L B. Relationship between carbonate facies in Guizhou and karst groundwater conditions[J].Hydrogeology&Engineering Geology,2016,43(1):6-11.(in Chinese)]
[7]陈卫昌,李黎,邵明申,等.酸雨作用下碳酸盐岩类文物的溶蚀过程与机理[J].岩土工程学报,2017,39(11):2058-2067.[CHEN W C,LI L,SHAO M S,et al. The dissolution process and mechanism of carbonate-like cultural relics under acid rain[J].Chinese Journal of Geotechnical Engineering,2017,39(11):2058-2067.(in Chinese)]
[8] WANG T J,JIN L S,LI Z K,et al. Modeling study on acid rain and recommended emission control strategies in China[J]. Atmospheric Environment,2000,34:4467-4477.
[9] BERNER R A. Rate control of mineral dissolution under earth surface conditions[J]. American Journal of Science,1978(9):1235-1252.
[10]张傲,方云,陈建平,等.凝结水对碳酸盐岩溶蚀实验及数值模拟分析[J].岩石力学与工程学报,2014,33(增刊2):3648-3656.[ZHANG A,FANG Y,CHEN J P,et al. Experimental and numerical simulation analysis of carbonate rock dissolution by condensate[J]. Chinese Journal of Rock Mechanics and Engineering,2014,33(Sup2):3648-3656.(in Chinese)]
[11]彭军,王雪龙,韩浩东,等.塔里木盆地寒武系碳酸盐岩溶蚀作用机理模拟实验[J].石油勘探与开发,2018,45(3):415-425.[PENG J,WANG X L, HAN H D, et al. Simulation experiment of dissolution mechanism of Cambrian carbonate rocks in Tarim Basin[J]. Petroleum Exploration and Development, 2018,45(3):415-425.(in Chinese)]
[12]朱立军,李景阳.岩溶环境中岩—土界面方解石的表面化学特征及其反应机理[J].中国岩溶,1997,16(1):20-24.[ZHU L J,LI J Y. Surface chemical characteristics and reaction mechanism of calcite at rock-soil interface in karst environment[J].Carsologica Sinica,1997,16(1):20-24.(in Chinese)]
[13] SUCHET P A, PROBEST J L. Modeling of atmospheric CO2consumption by chemical weathering of rock. Application to the Geronne, Congo and Amazon Basiona s[J]. Chemical Geology,1993,107(3/4):205-210.
[14] YUAN Daoxian. The carbon cycle in karst Z[J].Geomorph N F,1997,108:91-102.
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