Hydraulic pressure-resistant design of highway water-rich tunnels traversing exposed karst cave in karst area of peak cluster landform

2021 ◽  
Vol 14 (19) ◽  
Author(s):  
Yanping Ding ◽  
Linsheng Xu
2009 ◽  
Vol 58 (8) ◽  
pp. 1741-1748 ◽  
Author(s):  
Fang Guo ◽  
Guanghui Jiang

2014 ◽  
Vol 711 ◽  
pp. 402-405
Author(s):  
Li Wei Dong ◽  
Ping Cao ◽  
Jie Liu

Geotechnical engineering in large scale is endangered by the karst areas which are close to the engineering. The stability of the tunnels is greatly affected by the sizes and locations of the karst caves. Based on a engineering example, a study of the effects of karst area beneath the tunnel on the stability of surrounding rock is conducted. It can be concluded that the displacement release of surrounding rocks and the distribution of the vertical stress in surrounding rocks are greatly affected by the sizes of the karst caves and the distance between the tunnel floor and the karst cave.


2021 ◽  
Author(s):  
Qingmei Meng ◽  
Zhiyong Fu ◽  
Sheng Wang ◽  
Hongsong Chen

Abstract AimA deeper understanding of relationships between soil and vegetation is a prerequisite for accelerating karst area vegetation restoration. Remarkable achievements have been made at regional and individual plant scales, but research on the relationship between soil and vegetation is insufficient at the hillslope catena scale in karst areas.MethodsSoils and vegetation were investigated along a toposequence (upper-, middle-, lower-slope, and depression) of a dolomite peak-cluster depression catchment.ResultsA continuous soil catena pattern was developed along the toposequence. From the top to bottom of soil catena, soil thickness, fine soil mass ratio, nutrient stocks, and epikarst thickness gradually increased, while gravel mass ratio, pH, and saturated hydraulic conductivity gradually decreased. However, nutrient contents showed no significant change trends along the soil catena. There was a strong spatial association between soil types and dominant vegetation communities. The associations were as follows: herbs associated with entisols in the upper-slope; herbs and shrubs with inceptisols in the middle-slope; shrubs with semi-alfisols in the lower-slope; and trees with alfisols in the depression. ConclusionsThe dolomite rocks displayed an evenly progressive karstification process. This led to an undeveloped underground karstic network incapable of transporting soil materials into underground. Soil materials still accumulated at different topographic positions surface and formed a continuous catena. Parameters for nutrient stock may be more suitable for assessing soil productivity and to guide vegetation restoration key factors in karst regions than nutrient content parameters.


2011 ◽  
Vol 243-249 ◽  
pp. 3701-3706
Author(s):  
Qiang Chen ◽  
Bao Long Zhu

Since karst landform distributes widely in south China, highway and railway construction usually adopt the method of embedding long and large tunnel in great depth so that they could pass these karst areas safely. Water outburst and mud outburst accidents occurring on the stable karst area are major hazards in highway and railway construction and operation. The grave mud outburst accident occurring at the entrance of Yuanliangshan Tunnel has the following features: (1) the dissoluble rocks distribute widely, possessing a sound catchment capacity. (2) Water storage structure exists above the elevation of tunnel body; (3) feature of geologic structure and attitude of stratum in that area benefit the development of karst; (4) underground karst pipe is smooth and unobstructed. And there are certain underground rivers. (5) Besides, the thickness of water-proof layer has less power than the hydraulic pressure of ground water. (6) Karst mud outburst hazard features suddenness and concealment. Taken the example of Yuanliangshan Tunnel, the paper conducts preliminary analysis and careful calculation of the speed of karst mud outburst and its impact force, providing some research ground for disaster assessment and prevention.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Fei Xue ◽  
Minjun Cai ◽  
Tianzuo Wang ◽  
Tongyang Zhao

The existence of karst caves poses a large threat to safe tunnel construction in a karst area. This paper presents a synthetic method to evaluate the collapse risk before subway tunnel construction with Yang-Jian interval tunnel as a case study. The crosshole seismic Computed Tomography (CT) integrated with Geological Drilling (Geo-D) was first applied to accurately delineate the karst location and its scale. Then, 483 groups of seismic wave CT images were recorded, and 524 karst cave anomalies were found. The height of karst caves in the study area is 1–20 m and mainly concentrated at approximately 5 m. The vertical distance between the karst cave and the tunnel is mainly within 15 m. According to the detection results, a series of numerical models were built and calculated using FLAC3D to investigate the effect of different sizes and locations of karst caves on the displacement and stability of the surrounding rock in tunnels. Afterwards, based on the simulation results, the disturbance degree evaluation index was established to quantitatively evaluate the risk level of karst caves. The evaluation results indicate that the buried depth of the karst cave greatly affects the disturbance degree. No treatment is required for the deeply buried karst cave that is more than 7 m from the tunnel. When the distance between the cave and the tunnel is less than 7 m, there is a critical size of the cave. Karst caves that are larger than that critical value must be filled with a single slurry or binary slurry before tunnel construction to eliminate the risk of tunnel collapse. This study can be used to provide a more efficient and economical program for metro tunnel construction above a karst cave.


2021 ◽  
Vol 9 ◽  
Author(s):  
Yongshui Kang ◽  
Zhi Geng ◽  
Linhai Lu ◽  
Lei Chen ◽  
Xuewei Liu ◽  
...  

There is high risk of water inrush and ground collapse accidents when tunnelling in karst areas. Based on the case study of an urban metro tunnel, this paper focuses on karst cave treatment and waterproofing strategies for earth pressure balancing (EPB) shield tunnelling in karst areas containing large amounts of karst caves and fissures. When the shield machine enters the karst area, water gush easily occurs, posing serious threats to tunnelling safety. The distribution characteristic of limestone fractures, karst caves, and fissures in the karst area were analyzed according to the geological survey results. Further, water inrush risk and engineering difficulties were analyzed. Subsequently, a compound karst cave treatment and waterproofing strategy for EPB shield tunnelling was proposed and implemented. Water inflow is successfully reduced and ground collapse accident is avoided using the compound karst cave treatment and waterproofing strategy.


2014 ◽  
Author(s):  
Zhenzhong Cai ◽  
Chunduan Zhao ◽  
Xingliang Deng ◽  
Yanming Tong ◽  
Yangyong Pan ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document