Tunnel Digging Research Articles

Hygro-thermo-mechanical properties of tunnel excavated earth-based plasters

This paper aims to valorize the excavated earth (ExE) generated from the tunnel digging works, to elaborate excavated earth-based plasters for masonry walls. Excavated earth is an admixture of water, gravel, sand, and fine particles. A small amount of gravel (<4% by weight) was removed, and the tunnel-excavated earth is used to elaborate plasters. Cement and slag are used as stabilizers in ExE-based plasters and reinforced with natural hemp fibers. The physical, mechanical, thermal, and hydric properties of ExE-based plasters are investigated. The increase in cement content affects the workability of ExE-based plasters in a fresh state, while the addition of natural hemp fibers has no significant effect on the workability. It has been demonstrated that the mechanical performances (compressive strength, flexural strength, and dynamic modulus) of ExE-based plasters increase with the increase of cement content and decrease with the increase in slag content. The hemp fiber addition (0.8% by weight) shows no considerable effect on the ExE-based plaster’s mechanical performance. As for the thermal properties, the increase of cement and slag contents negatively affects the thermal conductivity. The increase in cement content decreases the water absorption of earth-plasters. Except for some tests (shrinkage, main cohesion, and cracking tests), which have not been done in this study, the results of cement-stabilized ExE-based plasters (7% and 9%) are in accordance with the recommendation of the DIN 18947 standard, indicating that the tunnel excavated earth can be used as earth-plasters.

Sediment transport by the burrowing activity of snow vole (Chionomys nivalis) in subalpine prairies of the Parâng Mountains (Romania): Quantitative modelling and methodological perspectives

Over the last decades, animal activity has been explored and reported as a potential source of natural hazards, such as the destruction of a beaver dam potentially triggering a flash flood downriver. However, the sediment source or sediment budget related to animal activity has received very little attention from geoscientists to date. The main goal of this study is to quantify the biogenic activity of the European snow vole (Chionomys nivalis) as a sediment source in the subalpine prairies of the Parâng Mountains, Southern Carpathians. Only the direct action of this rodent was analyzed, namely the spatial distribution and frequency of burrowing, quantitative analysis of the mounds, and rate of sediment excavation and mass transfer caused by burrowing and tunnel digging. To do this, 838 burrows and mounds were mapped and measured in eleven plots, and excavated volumes of sediment and mass transfers were calculated following three approaches: 1) measuring the weight of excavated debris; 2) measuring the dimensions of excavated debris; and 3) measuring burrow dimensions. The fieldwork revealed three preferred aspects: south, southeast, and west. The amount of displaced soil was highly variable depending on the approach used, ranging from 3.41 m3/ha to 21.08 m3/ha. As such, snow vole biogenic activity, which is due to the long-term opening of the landscape for traditional transhumance and sheep farming, should be considered to be an important sediment source in the subalpine and alpine prairies of the Parâng Mountain.

Rock Breaking Performance of TBM Disc Cutter Assisted by High-Pressure Water Jet

A high-pressure water jet can break rock efficiently, which is of great potential to overcome the problems of a tunnel boring machine (TBM) in full-face hard rock tunnel digging, such as low digging efficiency and high disc cutter wear rate. Therefore, this paper presented a new tunneling method that is a TBM coupled with a high-pressure water jet. The rock failure mechanism under the coupled forces of a disc cutter and water jet was analyzed at first. Then, the finite element method (FEM) and smoothed particle hydrodynamics (SPH) method were used to establish a numerical model of rock broken by the disc cutter and water jet. Effects of parameters on rock breaking performance were studied based on the numerical model. Moreover, an experiment of the water jet cutting marble was carried out to verify the reliability of the numerical simulation. Results showed that the high-pressure water jet can increase the TBM digging efficiency and decrease the forces and wear rate of the disc cutter. The optimum nozzle diameter is 1.5 mm, while the optimum jet velocity is 224.5 m/s in this simulation. The results can provide theoretical guidance and data support for designing the most efficient system of a TBM with a water jet for digging a full-face hard rock tunnel.

Ancient Mining and Metallurgy Activities in Mazayjan District, Fars Province

Ancient Mining and Metallurgy Activities in Mazayjan District, Fars Province

Experimental Study and Numerical Simulation of the Dynamic Behavior of Transversely Isotropic Phyllite

Abstract Understanding the dynamic mechanical behavior of transversely isotropic rocks is essential in various fields of rock engineering, such as tunnel digging, blasting, and underground excavati...

A Joint Sparsity Approach to Soil Detection Using Expanded Bands of WV-2 Images

Soil can be used as a damage indicator of landslides and flooding, which expose soil from vegetation canopy. It can also be used as an indirect indicator of illegal tunnel digging activity. This letter presents a sparsity-based approach to soil detection using multispectral satellite images, where both original and synthetic bands have been used. Spatial and spectral information has then been jointly used in soil detection. Extensive experiments clearly demonstrated the feasibility of our approach.

Structure of Tunnel Digging and Loading Trolley and Calculation of Electronic Control System and Analysis of Common Faults of Electronic Control

The tunneling truck is mainly used for tunneling construction. It has the functions of digging, loading, anchoring, and wet spraying.This paper analyses the main structure and working principle of tunnel digging and loading trolley, the selection and calculation of main electrical components, the overall calculation of tunnel digging and loading trolley, and the common electrical faults and troubleshooting methods. It has certain reference value for domestic counterparts.

The digging dynamics of ant tunnels: movement, encounters, and nest space

Underground ant nests are constructed by decentralised self-organisation wherein the ants respond to local stimuli and produce coordinated structures through globally regulated behaviours. One such regulation is the reduction in digging effort that occurs when available nest space has reached an adequate size. Tunnels have a distinct configuration relative to other nest elements and the processes regulating their excavation are poorly understood. We examined the relationship between digging effort and tunnel space by presenting groups of 10 Acromyrmex lundi workers with either short or long tunnel spaces and demonstrated that they will dig significantly less over time in a tunnel that is already long compared to one that is short. Additionally, we provided the same treatment to groups of 100 workers and found no significant effect of length, suggesting that group size has an important impact on tunnel excavation dynamics. Automated tracking was then used to examine tunnel digging in greater detail. Groups of 10 Atta colombica ants were tracked while excavating sand in a tunnel apparatus. There was a significant correlation between mean walking speed and excavation rate. Additionally, the ants would maintain a consistent level of proximity with each other over time. This suggests that as tunnel space expands, several factors combine to lower the chance of ants encountering the tunnel digging face and taking up excavation.

Investigating Effect of Tunnel Gate Shapes with Similar Cross Section on Inserted Forces on Its Coverage and Soil Surface Settlement

According to technology development and relative facilitation in digging and underground structures, ways, highways, all types of tunnels, underground train network, and other underground settle, storage are number of structure built and developed in advanced countries. In most situation, tunnel digging operations are done years after its construction or are not recorded in new structures regulations; therefore, this research investigates soil settlement and inserting force to tunnel coverage by limiting studies about effects of tunnel shapes on soil settlement using Plaxis, Seismo Signal, and Seismo Aspect. This study shows that rectangular tunnel has the most settlement in soil surface and circular tunnel has the least settlement but horseshoe tunnel has similar behavior to circular tunnel; however, earth subsidence level by digging this tunnel is more than circular tunnel. In addition, sectional shape has direct effect on inserting forces on tunnel coverage.

Functional Morphology of the Aardvark Tail

The musculoskeletal system of the aardvark (Orycteropus afer) tail was morphologically examined in two adult specimens. The tail musculature comprised three muscular groups, viz. a dorsal sacrocaudal system that consisted of the irregularly oriented Musculus sacrocaudalis dorsalis medialis and M.sacrocaudalis dorsalis lateralis, a lateral inter-vertebral connecting system, and a ventral sacrocaudal system characterized by the thick M.sacrocaudalis ventralis lateralis and M.sacrocaudalis ventralis medialis. Both the dorsal and ventral systems possessed large tendon groups that strengthened the tail structure. Computed tomography (CT) examination showed the presence of large but homogeneous cartilaginous inter-vertebral discs, whereas V-shaped bones were situated at the ventral aspect of the caudal vertebrae at the level of the inter-vertebral discs. CT visualization of the tendons and V-shaped bones in various tail positions suggested that these structures contribute to the tunnel digging action by bearing the trunk weight and lending force when the aardvark are displacing the soil by means of the forelimbs.

Work ability index in a cohort of railway construction workers

Working conditions and work load can have a significant effect on work ability, due not only to their direct impact on health and well-being, but also to the possibility they let to maintain job and competence at acceptable levels with normal ageing. In this perspective a cohort of 377 manual workers, aged between 21 and 67 years, engaged in a railway tunnel digging have been examined. They were miners, carpenters, maintenance workers, dumper drivers and clerks/storekeepers. In the whole cohort, the Work Ability Index resulted excellent in 23.6%, good in 47.2%, moderate in 24.4%, and poor in 4.8% of the workers (12.2% in those over 55 years). The mean WAI progressively decreases from the youngest to the oldest decade (from 41.5 in subjects under 25 years to 36.0 in subjects over 55 years), and passing from day-work (39.7) to semi-continuous three-shift work (39.2) and continuous 3-shift work (37.7). Miners and carpenters showed the highest percentages of poor-moderate WAI (31.6% and 35.1% respectively); these latter show also a steeper decrement over the years. Compared to other working groups of industrial and service sectors, the railway construction workers show the lower mean WAI scores at all age groups and the most pronounced decrease over decades.