Hard Rock Tunnel Research Articles

Estimation of Cerchar abrasivity index of granitic rocks in Turkey by geological properties using regression analysis

The estimation of abrasivity on granitic rocks is very important in mechanical excavators. The mineralogical composition and physico-mechanical properties of the rock affects of abrasivity properties such as the type and size of the mineral grains and strength. Tool wear is an important parameter in hard rock tunnelling and mining applications that are highly affected by rock abrasivity. The estimation of the Cerchar abrasivity index (CAI) from geological properties is useful for excavation costs. For this purpose, CAI, chemical, petrographical, physical and mechanical tests were carried out on 12 granitic rocks taken from different regions of Turkey. The test results were analysed using the method of least squares regression. Multiple regression models having good correlation coefficients were obtained for the granitic rocks. The CAI tests were correlated with chemical compound and a weak relation was determined. The regression analysis was also repeated for petrographical, physical, and mechanical properties. Statistically meaningful correlations were determined between all geological properties and CAI. Then multiple regression analysis was applied to all geological properties to find the more significant relations. Results show that shore scleroscope hardness, water absorption, and the waveness average prove to be the best for estimating CAI of granitic rocks.

Estimation of the performance of the tunnel boring machine (TBM) using uniaxial compressive strength and rock mass rating classification (RMR)–A case study from the Deccan traps, India

The competency of any TBM in any geological condition is determined by a rock or rock mass breakage process. A 12.24 km long tunnel between Maroshi and Ruparel College was excavated by Brihanmumbai municipal corporation (BMC) to improve water supply system of greater Mumbai, India, using open-type hard rock tunnel boring machines (TBMs). In this paper an attempt has been made to establish the relationship between rock mass characteristics i.e. RMR and UCS of the Deccan trap rocks and TBMs performance characteristics for 5.83 km long Maroshi–Vakola tunnel section of the Maroshi–Ruparel college tunnel project. To analyze the effect of variable rock mass conditions on the TBM performance, the operating parameters i.e. thrust force, torque and RPM of the machine, were recorded and intact rock strength was determined. The effect of rock mass properties on machine penetration rate (PR) and the relation with other operational parameters were analyzed. The rock strength affects the rock behaviour under compression. When the rolling cutters indent the rock, the stress exerted must be higher than the rock strength i.e.; the rock strength is directly relevant to the performance of TBM. Studies show that the penetration rate decreases with increase in uniaxial compressive strength (UCS). The comparison of measured penetration rate with empirical model developed by Graham, in which, the penetration rate is computed using UCS and average thrust per cutter, showed good agreement with coefficient of determination (R2), i.e. 0.97. The study shows that the TBM performance was maximum in rock mass rating (RMR) range from 40 to 75, while slower penetration was recorded both in very poor and very good rock masses.

Effects of Water Related Factors on Pre-grouting in Hard Rock Tunnelling

Water control is highly concerned for underground facilities, and rock grouting has been used over decades to reduce the water inflow. The performances of grouting are influenced by many factors such as rock type, joint distribution and grouting materials. In this paper, the effects of water related factors are focused, from the engineering perspective. The observed volume of water inflow from the probe drilling hole often serves as the base for judgment of grouting needs. The allowable limit of water inflow varies for underground facilities of different purposes. For similar underground facilities, such limit may also differ substantially in different regions. High pressure of underground water would increase difficulty for grouting. The water appearance may give indication on whether the fillings of joints or the weakness zones have been eroded. In the coastal area, the inflow water can be saline, and this needs to be taken into consideration to eliminate corrosion on electrical installations underground.

Adaptive Robust Coordinated Control for Over-actuated Cutter-head Driving Systems of Hard Rock Tunnel Boring Machines

Abstract: The cutter-head system of tunnel boring machines (TBM) is one of the key components for rock cutting and excavation. In this paper, the coordinated control problem is investigated for the over-actuated cutter-head driving system of TBM. A generalized nonlinear time-varying dynamic model is developed for the hard rock TBM cutter-head driving system. An adaptive robust control law integrated with control allocation technique is proposed, which controls the cutter-head to desired velocities while driving torques are well coordinated. Specially, the adaptive robust control (ARC) is used to deal with the negative effects of various uncertainties and variable loads acting on the cutter-head, and a coordinated control scheme with appropriate control allocation is developed to distribute the driving torque of each motor evenly. Comparative simulations are carried out to verify the excellent performance of the proposed scheme. The results suggest that, with the proposed control scheme, the motion performance is guaranteed and the driving torques are also well coordinated, validating the effectiveness and the performance improvement of the proposed control strategy.

The disassembly of Annabell and Joyce

Legacy Way is a 4.25 km twin tunnel which will connect the Western Freeway at Toowong to the Inner City Bypass at Kelvin Grove in Brisbane. Legacy Way is an initiative of Brisbane City Council and has been designed and constructed by Transcity, a joint venture of Brisbane based BMD Constructions, Spanish construction company Acciona and tunnelling specialist Ghella from Italy. The project’s two parallel tunnels were bored with two hardrock tunnel boring machines (TBMs) through approximately 3500 m of Bunya Phyllite and 700 m of Neranleigh-Fernvale with a UCS in the range of 60–100 MPa. These double-lane motorway tunnels will have cross passages approximately every 120 m throughout the tunnel and a smoke duct to remove smoke out of the tunnel in case of a fire. The westbound tunnel was excavated by the TBM named ‘Annabell’, whereas the eastbound tunnel was excavated by the TBM named ‘Joyce’.

Estimating extent and properties of blast-damaged zone around underground excavations

A common technique in hard rock tunneling, and underground excavation in general, is drilling and blasting. This method of excavation assumes that damage will be done to the surrounding rock mass depending on its quality. Herein is a proposal for how to estimate blast-damaged zone extent and shape, and how to quantify rock mass properties in this zone. Comparison was made, using FEM, between models with and without blast-damaged zone consideration through analyzing its impact on the support load. Results showed greater support loads in the case of blast-damaged zone modeling. Also, comparison was made between the proposed method for blastdamaged zone quantification and quantification using blast damage factor D. Results showed that in both cases, the support loads are in same magnitude order. In other words, compared to the blast damage factor D method, the proposed is more objective and makes it possible to describe the blasting process before it is actually done.

Fractal behaviour of the microseismic energy associated with immediate rockbursts in deep, hard rock tunnels

Rockbursts in tunnels can be a significant hazard. During the development of immediate rockbursts, a series of fractures is generated which can be monitored using microseismic events. A fractal calculation method has been proposed to study the self-similarity of the energy distribution of microseismic events during the development of immediate rockbursts. The proposed method was used to study the fractal behaviour of the energy distribution of microseismic events during the development of immediate rockbursts that occurred in four deep headrace tunnels and one drainage tunnel at the Jinping II hydropower project, China. The overburden of the studied tunnels, which are excavated in marble, is between 1900m and 2525m. The tunnels have a total length of 12.4km. The results indicated that the energy distribution of microseismic events during the development of immediate rockbursts has a fractal structure. The fractal behaviour of microseismic energy during the development of immediate strainbursts and immediate strain-structure slip rockbursts are distinguishable. The energy fractal dimensions of immediate strainbursts were larger than 0.2 but those of immediate strain-structure slip rockbursts were less than 0.2. For both immediate strainbursts and immediate strain-structure slip rockbursts, if the intensity was higher, the energy fractal dimensions were larger. The daily energy fractal dimension for microseismic events increased as approach of the immediate rockbursts. The energy fractal behaviour was used as a guide to establish a dynamic warning system based on the evolution of microseismic events to reduce the risk of immediate rockbursts during excavation of deep, hard-rock tunnels.

Considerations of rock dilation on modeling failure and deformation of hard rocks—a case study of the mine-by test tunnel in Canada

For the compressive stress-induced failure of tunnels at depth, rock fracturing process is often closely associated with the generation of surface parallel fractures in the initial stage, and shear failure is likely to occur in the final process during the formation of shear bands, breakouts or V-shaped notches close to the excavation boundaries. However, the perfectly elastoplastic, strain-softening and elasto-brittle-plastic models cannot reasonably describe the brittle failure of hard rock tunnels under high in-situ stress conditions. These approaches often underestimate the depth of failure and overestimate the lateral extent of failure near the excavation. Based on a practical case of the mine-by test tunnel at an underground research laboratory (URL) in Canada, the influence of rock mass dilation on the depth and extent of failure and deformation is investigated using a calibrated cohesion weakening and frictional strengthening (CWFS) model. It can be found that, when modeling brittle failure of rock masses, the calibrated CWFS model with a constant dilation angle can capture the depth and extent of stress-induced brittle failure in hard rocks at a low confinement if the stress path is correctly represented, as demonstrated by the failure shape observed in the tunnel. However, using a constant dilation angle cannot simulate the nonlinear deformation behavior near the excavation boundary accurately because the dependence of rock mass dilation on confinement and plastic shear strain is not considered. It is illustrated from the numerical simulations that the proposed plastic shear strain and confinement-dependent dilation angle model in combination with the calibrated CWFS model implemented in FLAC can reasonably reveal both rock mass failure and displacement distribution in vicinity of the excavation simultaneously. The simulation results are in good agreement with the field observations and displacement measurement data.

A new technology for hard-rock tunneling based on drilling and hydraulic impact breaking

In order to realize the safety, high efficiency and rapidity of hard rock tunneling, we propose the drilling & hydraulic impact hard-rock tunneling (DHIHT) technology and method. Based on the LS-DYNA explicit module and APDL programming, the key parameters of DHIHT, including drilling spacing and drilling radius, were investigated. The simulation results show that: the drilling spacing should not exceed 0.20m-larger distances weaken the actual breaking effect; the best drilling radius is about 0.035m, larger or smaller distances would both decrease the effect of drilling-hole free surfaces. The field impact breaking experiments were conducted in Baitaizi township granite quarry, Jinzhou, Liaoning province, China. The experiment results indicate that DHIHT is a feasible method for hard-rock tunneling, but its efficiency still needs to be further optimized and improved.

New Rock Abrasivity Test Method for Tool Life Assessments on Hard Rock Tunnel Boring: The Rolling Indentation Abrasion Test (RIAT)

The tunnel boring machine (TBM) method has become widely used and is currently an important presence within the tunnelling industry. Large investments and high geological risk are involved using TBMs, and disc cutter consumption has a great influence on performance and cost, especially in hard rock conditions. Furthermore, reliable cutter life assessments facilitate the control of risk as well as avoiding delays and budget overruns. Since abrasive wear is the most common process affecting cutter consumption, good laboratory tests for rock abrasivity assessments are needed. A new abrasivity test method by rolling disc named Rolling Indentation Abrasion Test (RIAT) has been developed. The goal of the new test design and procedure is to reproduce wear behaviour on hard rock tunnel boring in a more realistic way than the traditionally used methods. Wear by rolling contact on intact rock samples is introduced and several rock types, covering a wide rock abrasiveness range, have been tested by RIAT. The RIAT procedure indicates a great ability of the testing method to assess abrasive wear on rolling discs. In addition and to evaluate the newly developed RIAT test method, a comprehensive laboratory testing programme including the most commonly used abrasivity test methods and the mineral composition were carried out. Relationships between the achieved results from conventional testing and RIAT results have been analysed.

Performance Assessment of Hard Rock TBM and Rock Boreability Using Punch Penetration Test

Rock indentation tests are often called punch penetration tests and are known to be related to penetration rates of drilling equipment and hard rock tunnel boring machines (TBMs). Various indices determined from analysis of the force-penetration plot generated from indentation tests have been used to represent the drillability, boreability, and brittleness of rocks. However, no standard for the punch penetration test procedure or method for calculating the related indices has been suggested or adopted in the rock mechanics community. This paper introduces new indices based on the punch test to predict the performance of hard rock TBMs. A series of punch tests was performed on rock specimens representing six rock formations in Korea with different dimensions, i.e., the core specimens had different lengths and diameters. Of the indices obtained from the punch tests, the peak load index and mean load index showed good correlations with the cutting forces measured in full-scale linear cutting machine tests on the same rock types. The indices also showed good linear correlations with the ratio of uniaxial strength to Brazilian tensile strength, which indicates the brittleness of rock. The scale effect of using core specimens was investigated, and a preferred dimension for the punch test specimens is proposed. This paper also discusses the results of the punch test and full-scale rock cutting tests using LCM. The results of this study confirm that the proposed indices from the punch tests can be used to provide a reliable prediction of the cutting forces that act on a disc cutter. The estimated cutting forces can then be used for optimization of cutter-head design and performance prediction of hard rock TBMs.

Disc cutter wear prediction for a hard rock TBM cutterhead based on energy analysis

Disc cutter wear is a crucial problem that influences the working efficiency and security of hard rock tunnel boring machines (TBMs). This wear results from friction energy accumulation and conversion. In this study, the process of hard rock TBM disc cutter wear is identified and analyzed by quantifying the collective energy change. This study starts with an analysis of the friction process between the disc cutter and hard rock. The relationship between the rolling force work and thrust force work of the disc cutter is examined. As a result, the disc cutter energy equation is determined, and the meaning of the upper and lower bounds of this equation are discussed. Based on the above results, the hard rock TBM cutterhead energy equation is then deduced. A method to identify the friction work is developed. According to the energy wear theory, the cutter wear law on hard rock for a TBM cutterhead is revealed, and a method for predicting disc cutter wear for a hard rock TBM cutterhead is advanced. Furthermore, the validity of this prediction method is confirmed by utilizing data from project cases.

Thrust and torque characteristics based on a new cutter-head load model

Full face rock tunnel boring machine(TBM) has been widely used in hard rock tunnels, however, there are few published theory about cutter-head design, and the design criteria of cutter-head under complex geological is not clear yet. To deal with the complex relationship among geological parameters, cutter parameters, and operating parameters during tunneling processes, a cutter-head load model is established by using CSM(Colorado school of mines) prediction model. Force distribution on cutter-head under a certain geology is calculated with the new established load model, and result shows that inner cutters bear more force than outer cutters, combining with disc cutters abrasion; a general principle of disc cutters’ layout design is proposed. Within the model, the relationship among rock uniaxial compressive strength(UCS), penetration and thrust on cutter-head are analyzed, and the results shows that with increasing penetration, cutter thrust increases, but the growth rate slows and higher penetration makes lower special energy(SE). Finally, a fitting mathematical model of ZT(ratio of cutter-head torque and thrust) and penetration is established, and verified by TB880E, which can be used to direct how to set thrust and torque on cutter-head. When penetration is small, the cutter-head thrust is the main limiting factor in tunneling; when the penetration is large, cutter-head torque is the major limiting factor in tunneling. Based on the new cutter-head load model, thrust and torque characteristics of TBM further are researched and a new way for cutter-head layout design and TBM tunneling operations is proposed.

TBM tunnelling in hard rock and in soil / TVM‐Vortrieb in Fest‐ und Lockergesteinen

Geomechanics and TunnellingVolume 8, Issue 3 p. 182-183 EditorialFree Access TBM tunnelling in hard rock and in soil / TVM-Vortrieb in Fest- und Lockergesteinen Kurosch Thuro, Kurosch ThuroSearch for more papers by this author Kurosch Thuro, Kurosch ThuroSearch for more papers by this author First published: 01 June 2015 https://doi.org/10.1002/geot.201590020AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume8, Issue3June 2015Pages 182-183 RelatedInformation

Investigation of H13 Alloy Cutter Behaviour for Hard Rock Tunneling Applications

The current paper first analyzed the degradation mechanisms of the worn disc cutter made of forged H13 chromium alloy for hard rock tunneling applications. The paper investigated subsequently the mechanical properties of H13 to have a better understanding of the degradation mechanisms. Hardness tests were carried out on different positions on a cutter. Tensile tests and fracture toughness were carried out to investigate temperature effects. The test results showed that the material has a high wear resistance and a good temperature resistance, but its quasi brittle behavior and the residual stress effect (due to the cutting process) is critical for the chipping damage of the disc cutter.

Moisture Transport Through Sprayed Concrete Tunnel Linings

Waterproofing of permanent sprayed concrete tunnel linings with sprayed membranes in a continuous sandwich structure has been attempted since 2000 and has seen increased use in some countries. The main function of a sprayed membrane from a waterproofing perspective is to provide crack bridging and hence prevent flow of liquid water into the tunnel through cracks and imperfections in the concrete material. However, moisture can migrate through the concrete and EVA-based membrane materials by capillary and vapor diffusion mechanisms. These moisture transport mechanisms can have an influence on the degree of saturation, and may influence the pore pressures in the concrete material as well as risk of freeze–thaw damage of the concrete and membrane. The paper describes a detailed study of moisture transport material parameters, moisture condition in tunnel linings and climatic conditions tunnels in hard rock in Norway. These data have been included in a hygrothermal simulation model in the software WUFI for moisture transport to substantiate moisture transport and long-term effects on saturation of the concrete and membrane material. The findings suggest that EVA-based membranes exhibit significant water absorption and vapor transport properties although they are impermeable to liquid water flow. State-of-the-art sprayed concrete material applied with the wet mix method exhibits very low hydraulic conductivities, lower than 10−14 m/s, thus saturated conductive water flow is a very unlikely dominant transport mechanism. Moisture transport through the lining structure by capillary flow and vapor diffusion are calculated to approximately 3 cm3/m2 per day for lining thicknesses in the range of 25–35 cm and seasonal Nordic climate variations. The calculated moisture contents in the tunnel linings from the hygrothermal simulations are largely in agreement with the measured moisture contents in the tunnel linings. The findings also indicate that the concrete material exhibits a reduction of saturation on the immediate inside of the membrane. Near the location of the waterproofing membrane on either side, the concrete material exhibits degrees of capillary saturation between 85 and 95 %. Moisture content in the membrane is found to be consistently in the range of 12–17 % by weight, corresponding to a degree of saturation of 30–35 %. Possible effects of such moisture contents are lower risk of freezing degradation, higher tensile bonding strengths at the membrane interfaces, and a reduced risk of pore pressure in the concrete material.

Study on Effect of Blasting Vibration on Surface of Particles in Urban Hard Rock Tunnel

Put the first Phase Project of Qingdao Metro (line 3) civil 03 bid section TAI-YAN interval of blasting construction as the background In this paper,select the test section to blasting test,in groundposition on the ais of the tunnel workface arrange the measuring points and location of measuring points remain the same.Based on the measured data, studied on the law of blasting vibration of cutting parts of each of the driving cycle.The research result show that the cutting part of vibration velocity peak appeared in behind the tunnel woekface 1~3m;Rear vibration composite speed of the tunnel workface is speed of the tunnel workface is 1.0~1.4 times in front of the particle vibration composite speed;The main vibration frequency in front of tunnel workface and rear particles are above 15HZ.

Identification of heavy weight type roadheaders performance based on field data

In Japan, it is necessary to excavate many hard rock tunnels using a heavy weight (200-300kW class) axial and transverse cutter head type roadheaders, which has reason for various conditions of saving the environment from the construction site and so on. And the performance of a heavy weight axial and transverse cutter head type roadheaders is a critical issue in assessing technical and economic feasibility of its application in many tunneling projects. Therefore, the authors have established a database of heavy weight axial and transverse cutter head type road-headers performance, which based on the interview for engineer's of many tunnel construction projects. This database contains field data from the civil construction operations all over Japan, includes a variety of heavy weight roadheaders of different geotechnical conditions and different cutter head type. And, this database refers to accurate estimation of the production rate, machine utilization and picks consumption for different geological units to be encountered on the tunnel project planning. This paper presents and discusses the performance estimation model of instantaneous cutting rate (ICR) and pick consumption which was introduced rock quality designation index (RQD) from this database. Especially this database established form hard rock tunnel excavated data using heavy weight (200-300kW class), axial and transverse cutter head type road headers.

Research on the Hard-Rock Breaking Mechanism of Hydraulic Drilling Impact Tunneling

In order to realize the rapid hard-rock tunneling in a safe, highly effective, and economic manner, the hydraulic drilling impact hard-rock tunneling (HDIHT) technology and method were introduced based on the theories of rock mechanics and hydraulic impact. The key parameters, including drilling radius and impact distance, were researched to reveal the stress behavior during HDIHT process. The Von Mises equivalent stress and its principal stress components were analyzed, and the breaking mechanism of HDIHT was also discussed. The simulation results show that, to ensure the effectiveness of “secondary breaking” caused by drilling hole free surfaces, the impact distance should not exceed 200 mm, and the optimal drilling radius was about 35 mm.

Research on the Simulation of Cutting Rock Rotary by Hard Rock Tunnel Boring Machine Disc Cutters

Research on the Simulation of Cutting Rock Rotary by Hard Rock Tunnel Boring Machine Disc Cutters