Investigation on the Effect of Cyclic Moisture Change on Rock Swelling in Hydropower Water Tunnels

Selen, Lena; Panthi, Krishna Kanta; Vergara, Maximiliano R.; Mørk, Mai Britt E.

doi:10.1007/s00603-020-02266-1

Cited by 5 publications

(4 citation statements)

References 11 publications

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“…To do so, the swelling potential of intact rocks are first assessed by conducting mineralogical test to identify swelling clay minerals such as montmorillonite, anhydrite, zeolite etc. The next step will then be to carry out swelling pressure tests in intact rock samples in repeated cycles of drying and wetting (Selen et al, 2021). An example of such tests is shown in Figure 10.…”

Section: Operation Of Presure Tunnels In Swelling Rocksmentioning

confidence: 99%

Engineering Geology in Hydropower Engineering

Panthi

2023

The IV Nordic Symposium on Rock Mechanics and Rock Engineering - Proceedings

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"Norway has more than 100 years of experience in the design and construction of hydropower plants consisting waterway systems that included unlined pressure tunnels and shafts. The waterway systems are in general very long and consist of unlined pressurized headrace tunnels, unlined high-pressure shafts, underground powerhouse caverns, access, and tailrace tunnels. The maximum static head that the unlined pressure tunnel has reached is 1047 meter, which is equivalent to almost 10.5 MPa. This is a world record, and it is obvious that the rock mass in the periphery of unlined pressure tunnels and shafts experience high hydrostatic pressure exerted by the flowing water discharge. Experienced gained from the construction and operation of these unlined pressure tunnels and shafts were the key to develop design criteria and stability assessment principles by giving focus on engineering geology, rock mass quality and geo-tectonic environment. As a result, these criteria and principals have got worldwide acceptance. However, the success of these criteria depends on the engineering geological and geo-tectonic environment prevailing in the are of concern and the operational regime adopted in the hydropower plants. This key-not lecture reviews some of the first attempts of the use of unlined pressure tunnels and shafts concept, highlights major failure cases, discusses the gradual development of design criteria for the unlined pressure tunnels and shafts and highlights recent operational trends that have direct influence on the stability of unlined pressure tunnels and shafts of hydropower plants."

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Section: Operation Of Presure Tunnels In Swelling Rocksmentioning

confidence: 99%

Engineering Geology in Hydropower Engineering

Panthi

2023

The IV Nordic Symposium on Rock Mechanics and Rock Engineering - Proceedings

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“…The process of gypsum hydration to gypsum was gypsum expansion. During this process, expansion force will be generated on the tunnel lining; at the same time, gypsum softening will reduce the strength of the surrounding rock (Tang and Tang, 2012;LiuShui et al, 2014;Vergara and Triantafyllidis, 2016;Selen et al, 2020).…”

Section: ) Softening and Expansion Of The Gypsum And Anhydritementioning

confidence: 99%

“…Swelling rock is a special soft rock that expands and softens with water, shrinks and disintegrates after water loss which is different from other rocks (Fan et al, 2019(Fan et al, ,2020Liu et al, 2020aLiu et al, , 2020bHe et al, 2021a, He et al, 2021bKang et al, 2021;Zhang et al, 2021a). It has special engineering characteristics and easily causes tunnel disasters, which has a great impact on project cost and safe operation (LiuShui et al, 2014;Tang and Tang, 2012;Selen et al, 2020;Vergara and Triantafyllidis, 2015).…”

Section: Introductionmentioning

confidence: 99%

Failure Characteristics and Treatment Measures of Tunnels in Expansive Rock Stratum

Yang

Liu

et al. 2022

Front. Earth Sci.

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During the operation period, disasters caused by the expansion of tunnel surrounding rock often occurs, but the understanding of this problem is still insufficient. This study investigated the disaster that occurred in the tunnel based on numerical simulation on a case in Dugongling, China. First, the main diseases, including lining cracks, pavement uplift and cable trench overturning and so on, of the tunnel were investigated in the field. According to the geological data, the expansion and softening of the surrounding rock was likely to be the main cause of lining cracking. Then, this paper proposed a formula for calculating the expansion force of expansive rock when the water content changes. Based on the expansion force calculation formula, the most severely damaged section was numerically analyzed, and the results were compared with the on-site monitoring data. According to the simulation results, the deformation of the surrounding rock and the stress of the supporting structure were studied. The research showed that the expansion and softening of the surrounding rock led to an increase in the load acting on the lining structure, which intensified the development of disasters. Finally, four reinforcement schemes were proposed and simulated, and the best reinforcement scheme was evaluated. The results of this study can provide a reference for the design and construction of this project and similar projects.

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“…Flat jack is one of the reliable technologies that have been used by many researchers in measuring in-situ stresses in mining and civil structures. Comprehensive information on flat jack testing can be found in the relevant literature (Bieniaweki, 1981;ISRM, 1986;Binda and Tiraboschi, 1999;Gregorczyk and Lourenco, 2000;Fedele and Marier, 2007;Verstricht et al, 2010;Lamas, Muralha, and Figueiredo, 2010;Muralha, 2010, 2011;Simoes et al, 2012;Dhawan, 2012;Sabri, Ulybin, and Zubkov, 2015;He and Hatzor, 2015;Cescatti et al, 2016;Latka and Matysek, 2017;Mendola, Giudice, and Minafo, 2019;Selen et al, 2020;Corkum, 2020;Armanasco and Foppoli, 2020;Rios and O' dwayer, 2020;Medeiros, Soriani, and Parsekian, 2020, amongst others) Pakistan produces around 3,193,791 Mt of rock salt per annum (Mines and Minerals Department, 2020). Due to the massive nature of the deposits, mines have mostly multi-level operations developed using the stope-and-pillar method with regular layouts.…”

Section: Introductionmentioning

confidence: 99%

Stability evaluation of room-and-pillar rock salt mines by using a flat jack technique - A case study

Majeed

Abbas

Emad

2023

J. S. Afr. Inst. Min. Metall.

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Room-and-pillar mining is commonly employed for the extraction of rock salt in underground mines. Pillar stress is a major concern in these mines as it is directly related to stability and mineral recovery. In this study a flat jack method was used to measure pillar stresses in three underground rock salt mines in Pakistan. The field work included determination of in-situ stress, in-situ elastic modulus, recording of field variables (pillar length and width, height and width of opening, opening width to height ratio, extraction ratio, and overburden height) and collection of salt block samples. The geomechanical properties of rock salt (uniaxial compressive strength, Young's modulus, Brazilian tensile strength, and density) were also determined to estimate overburden stress, pillar strength, and factor of safety (both estimated and actual). It was found that the measured pillar stresses are proportional to the overburden stress values, with their magnitude ranging from 6.05 MPa to 11.97 Mpa, and the pillars were found to be stable. Regression analysis was performed to develop statistical models for in-situ stress and in-situ elastic modulus. Finally a quick guideline chart was developed to determine the suitable length of pillar for a given span and required level of safety. Keywords: flat jack, room-and-pillar mining, in-situ stress, factor of safety, regression analysis.

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Investigation on the Effect of Cyclic Moisture Change on Rock Swelling in Hydropower Water Tunnels

Cited by 5 publications

References 11 publications

Engineering Geology in Hydropower Engineering

Engineering Geology in Hydropower Engineering

Failure Characteristics and Treatment Measures of Tunnels in Expansive Rock Stratum

Stability evaluation of room-and-pillar rock salt mines by using a flat jack technique - A case study

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