Stability of rectangular tunnels in weathered rock subjected to seepage forces

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Puja Dutta ◽  
Paramita Bhattacharya
Keyword(s):  
Weathered Rock

scholarly journals Chitinophaga longshanensis sp. nov., a mineral-weathering bacterium isolated from weathered rock

2015 ◽  
Vol 65 (Pt_2) ◽  
pp. 418-423 ◽  
Author(s):  
Shan Gao ◽  
Wen-Bin Zhang ◽  
Xia-Fang Sheng ◽  
Lin-Yan He ◽  
Zhi Huang
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Sequence Similarity ◽  
Mineral Weathering ◽  
Rrna Gene ◽  
Phenotypic Properties ◽  
Content Type ◽  
Weathered Rock ◽  
Link Type ◽  
Type Strains

A Gram-stain-negative, aerobic, yellow-pigmented, non-motile, non-spore-forming, rod-shaped bacterial strain, Z29T, was isolated from the surface of weathered rock (potassic trachyte) from Nanjing, Jiangsu Province, PR China. Phylogenetic analysis based on 16S rRNA gene sequences suggested that strain Z29T belongs to the genus Chitinophaga in the family Chitinophagaceae . Levels of 16S rRNA gene sequence similarity between strain Z29T and the type strains of recognized species of the genus Chitinophaga ranged from 92.7 to 98.2 %. The main fatty acids of strain Z29T were iso-C15 : 0, C16 : 1ω5c and iso-C17 : 0 3-OH. It also contained menaquinone 7 (MK-7) as the respiratory quinone and homospermidine as the main polyamine. The polar lipid profile contained phosphatidylethanolamine, unknown aminolipids, unknown phospholipids and unknown lipids. The total DNA G+C content of strain Z29T was 51.3 mol%. Phenotypic properties and chemotaxonomic data supported the affiliation of strain Z29T with the genus Chitinophaga . The low level of DNA–DNA relatedness (ranging from 14.6 to 29.8 %) to the type strains of other species of the genus Chitinophaga and differential phenotypic properties demonstrated that strain Z29T represents a novel species of the genus Chitinophaga , for which the name Chitinophaga longshanensis sp. nov. is proposed. The type strain is Z29T ( = CCTCC AB 2014066T = LMG 28237T).

Analysis on Effect of Tunnel Crossing Underneath Foundation of Tall Buildings on Anti-Seismic Mortar Anchor in Weathered Rock Area

2012 ◽  
Vol 446-449 ◽  
pp. 2581-2589
Author(s):  
Xiao Bei Shi ◽  
Kai Wei ◽  
Bing Long Wang ◽  
Da Wei Huang
Keyword(s):  
High Speed ◽  
Failure Process ◽  
Tall Buildings ◽  
Element Model ◽  
Tunnel Excavation ◽  
High Speed Railway ◽  
Weathered Rock ◽  
Whole Process ◽  
Influence Area ◽  
Before And After

Depending on a project of constructing a tunnel of high-speed railway which crosses underneath the foundation of tall buildings in weathered rock area, the paper analyzes the failure process and its law of anti-seismic mortar anchors under the foundation of tall buildings by simulating the whole process of construction with finite element model. Then the coverage scope, influence rules and extent of tunnel excavation on the anti-pulling effect and stability of mortar anchors are analyzed according to the changes of lateral pressure and axial force of anti-seismic mortar anchors before and after construction. The results show that the influence area can be divided into three parts， of which the main area where the anti-seismic mortar anchors are badly affected is on the top of the tunnel and extends horizontally to a certain range. Finally, the paper gives an applicable method to estimate the area where the anti-seismic mortar anchors should be strengthened by grouting, which also applies to the similar projects in weathered rock area.

Field P–y curves in weathered rock

2007 ◽  
Vol 44 (7) ◽  
pp. 753-764 ◽  
Author(s):  
Kook Hwan Cho ◽  
Mohammed A Gabr ◽  
Shane Clark ◽  
Roy H Borden
Keyword(s):  
Field Tests ◽  
Drilled Shafts ◽  
Drilled Shaft ◽  
Weak Rock ◽  
Strain Gages ◽  
Weathered Rock ◽  
Clay Model ◽  
Rock Model ◽  
Stiff Clay ◽  
Subgrade Modulus

In weathered and decomposed rock profiles, the lack of an acceptable analysis procedure for estimating lateral load–displacement response of drilled shafts is compounded by the unavailability of weathered material properties, including the material's lateral subgrade reaction modulus. Such deficiency often leads to the overdesign of the drilled shaft foundation. Six field tests were conducted on drilled shafts to investigate the shape and magnitude of P–y curves in weathered rock material at three locations in North Carolina. The tested shafts were instrumented using dial gages, strain gages, and continuous vertical inclinometers. The measured load versus deflection data are used to study the stiffness response of weathered rock. Measured lateral responses are compared with the results estimated based on a "weak rock" model and a stiff clay model. The comparison shows that Reese's weak rock model overestimated the resistances of the tested shafts while the stiff clay model consistently underestimated the measured shaft resistances. The measured and computed results are analyzed and discussed.Key words: drilled shaft, weathered rock P–y curve, subgrade modulus, ultimate resistances in weathered rock, verification tests.

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