Preliminary exploration on the critical buried depth of the soil cave in karst area
-
摘要: 在岩溶土洞发育地区进行工程建设时需要确定土洞是否会发展成地面塌陷和对工程结构物稳定性有影响,分析表明土洞临界深度可作为评价土洞稳定和加固深度的依据。本文采用有限元分析方法,以土洞塑性区贯通至地面或路基表面作为土洞发展成地面塌陷和临界深度的标准。研究表明,土洞的临界深度与土洞形状、土洞尺寸、位置和路基填土厚度有关;土洞断面形状为圆形时临界深度最小,土洞尺寸越大,路基填土越厚,相应土洞临界深度越大。Abstract: The research area is situated in a karst area with shallow cover type of karst developed, where the overlying soil layer comprises cultivated soil, silty clay, muddy clay, breccia and gravel and the underlying bedrock is limestone. The soil caves are developed in the soil layer, which often cause the ground to collapse. A single soil cave’s size is 2 m to 5 m in both height and width, with a long longitudinal extension. The plane distribution of soil caves is consistent with the ground collapse. On the basis of their transverse section, the caves can be roughly as circular and tunnel types, the latter of which has the shape of semicircular upper part and rectangle lower one. The highway passing through the area normally has a road embankment of 5.5 m to 7.5 m high. In order to determine the scope of the treatment of the soil caves, it is necessary first of all to determine whether a cave will develop into ground collapse. Based on the detailed investigation of the site, the location, size and shape of the soil cave are recorded, from which a finite element analysis model is established. Taking the zone from ground surface or road embankment surface to underground plastic deformation area into account for the determination of critical buried depth of the soil caves which may develop into ground collapse, the critical buried depth of the soil cave stability in different depth, size, shape and different backfilling height is then analyzed. This research has showed that the critical buried depth of soil cave is closely related to the shape, size and location of the caves and the thickness of roadbed fillings. The critical buried depth has a minimum value at the circular cave, while it gets larger along with increasing cave size or roadbed filling thickness. The results of this research can be used as a basis for the treatment measures towards the soil cave collapse. When the buried depth of the cave is larger than the critical buried depth, there is no need to treat it. On the contrary, when the buried soil cave is shallower than the critical buried depth, it is necessary to deal with the soil cave. In order to ensure that the soil caves do not have harmful effects on the highway project, field monitoring should be carried out both during and after road construction; and it is accordingly suggested that immediate intervention measures need to be implemented for the problematic localities.
-
Key words:
- stability /
- critical buried depth /
- finite element analysis /
- soil cave in karst area
-
[1] 工程地质手册编委会.工程地质手册(第四版)[M].北京:中国建筑工业出版社,2010:532-535. [2] 蒋小珍,雷明堂,管振德.单层土体结构岩溶土洞的形成机理[J].中国岩溶,2012, 31(4):426-432. [3] 韦俊发,麻荣广,杨彰智,等.广西来宾凤凰变电站土洞塌陷形成机理及其治理[J].中国岩溶,2013,32(3):325-329. [4] 〖JP2〗Thomas M Tharp. Mechanics of upward propagation of covered collapse sinkhole[J].Engineering Geology,1999,52(1-2):23-33. [5] 贾龙,蒙彦,管振德.岩溶土洞演化及其数值模拟分析[J].中国岩溶,2014,33(3):294-298. [6] 李万有,陈立龙,李爽.覆盖层的抗剪强度与土洞型岩溶塌陷高度关系的数值分析研究[J].林业科技情报,2010,42(1):102-104. [7] 王滨,贺可强.岩溶塌陷临界土洞的极限平衡高度公式[J].岩土力学,2006,27(3):458-462. [8] 刘之葵,周健红,朱寿增.公路路基中溶洞及土洞顶板安全厚度和距离的确定[J].路基工程,2006,(1):119-121. [9] 丁春林,甘百先,钟辉虹,等.含土洞、溶洞的机场滑行道路基稳定性评估[J].岩石力学与工程学报,2003,22(8): 1329-1333. [10] 赵帅军.武广客运专线英德段厚覆盖型岩溶区土洞顶板稳定性研究[D].成都:成都理工大学,2009. [11] 肖武权.娄新高速公路岩溶发育特征与地基处理方案优化研究[J].中国岩溶,2013,32(2):161-166.
点击查看大图
计量
- 文章访问数: 1913
- HTML浏览量: 369
- PDF下载量: 1456
- 被引次数: 0