Excavation Techniques Research Articles

An Investigation on Longitudinal Surface Subsidence Deformation of Large-Span Undercut Metro Tunnel

Underground excavation techniques are frequently used in subway stations during the construction of urban rail transit. The current study analyzes and investigates the surface settlement and deformation laws of large-span shallow buried underground excavated stations depending on a vast quantity of measured data from the Qingdao Metro Line 3. According to the comprehensive study, obtained results show that: 1) the excavation of pilot tunnels on both sides will result in the longitudinal settlement at the ground surface; however, the settlement will be quite minor, within −10 mm. During the excavation of the middle part of the pilot tunnel, large surface settlement may occur, and the settlement may reach −30 mm, while during the excavation of the lower soil and construction of the station structure, the surface settlement changes insignificantly, and some monitoring points show a sinking trend. 2) Data fitting reveals that regression analysis with a one variable cubic polynomial produces excellent fitting results. In addition, the analysis based on statistical methods reveals that the conditions of the surrounding rock are poor (Class that the arch, and the overall buried depth of the station is not larger than 10 m. 3) Since the surface settlement control standard for large-span boring tunnels is −60 mm, using −48 mm as the warning value is more reasonable. The test conducted in the current study has helped accumulate a large amount of ground settlement monitoring data, which can provide a particular reference for the subsequent design of similar lines.

Historical underground quarrying: A multidisciplinary research in the Caumont quarry (c. 13th–19th centuries), France

AbstractQuarries represent ‘landscapes archives’ as they supplied the stone required for historical buildings. Among them, the Caumont ancient quarry stands out in northern France, with its huge dimensions and its historical role, providing building stones at a regional scale since at least the Middle Ages. The present study aims to approach the quarrying methods used over time in Caumont by means of an optimized methodological approach. The designed methodology combines (1) the 3D modelling of the quarry, (2) archaeological prospection, (3) stratigraphical and microscopical study of the quarried bedrock, and (4) the geochronological approach in stalagmites precipitated inside the quarry. The studied quarry of Caumont was excavated as an open‐cast quarry beginning with the escarpments along the River Seine and transformed later to an underground quarry supported by contoured bedrock pillars. The underground quarry with its 12 km of galleries shows a chambers‐and‐pillars pattern style excavated using two methods, producing an inferred volume of 273,529 m3 of building stone. The U–Th dating of two stalagmites suggests that quarrying activity had begun since at least the early medieval period and agrees with the excavation techniques and historical documents.

Management preference of deep carious lesion in permanent mature teeth among dentists in Riyadh city

Introduction: The management of deep caries lesion can be accomplished by complete caries excavation, partial caries removal, and stepwise excavation techniques. Dentists do not agree on a single management due to available evidence about the effectiveness of different treatment options of deep carious lesion that are inconsistent. Aim: The aim is to investigate the attitude and behavior of management preference of deep caries in mature permanent teeth among dentists in Riyadh city. In addition, to compare these findings with academic standards, World Dental Federation and International Caries Consensus cooperation (ICCC). Materials and Methods: A randomized cross-sectional study was conducted in which 540 questionnaires were distributed to dentists in Riyadh city. The questionnaire included four clinical scenarios to investigate the participant's attitude and behavior of management preference of deep carious lesion of permanent teeth in Riyadh city in 2019. Results and Discussion: Response rate was 74%. Findings illustrate that 86.8% of participants preferred complete caries excavation in case of deep caries with no pain nor risk of pulpal exposure. 41.3% of the participants preferred complete caries excavation in case of deep caries with no pain but risk of pulpal exposure presence. 64.8% participants preferred complete caries excavation in case of deep caries with pain on provocation and no risk of pulpal exposure. 58.3% participants preferred root canal treatment in case of deep caries with pain on provocation and with risk of pulpal exposure. About 76.80% of participants believed that after 2 years from complete caries removal, a high success rate (more than 80%) will result. Conclusion: The majority of participants prefer more invasive approaches in the treatment of deep carious lesions and unaware of the minimally invasive dentistry.

Manajemen Risiko Keselamatan Dan Kesehatan Kerja (K3) Pada Pekerja Penambang Pasir Kali Dentunura Kecamatan Nangaroro Kabupaten Nagekeo

Sand mining workers are part of the procurement of materials for construction activities, so they need to beconsidered because the risk opportunities are quite large. In this study, the risk assessment method uses arisk assessment matrix. After collecting the data, it is then analyzed to find out how big the risk is to the sandmining workers of the Ventura River. The results of this study obtained that the risk due to employees(workers) having received assistance index 6.06, moderate risk category, risk due to accidents to employees(workers) index 11.34 very high-risk category, risk due to using index tool 11.01 very risk category. high risk,material, and dust risk index 14.82, including very high-risk category, risk due to bad weather index 12.96,very high-risk category, risk index due to accidental fracture of legs and arms 7.53, included in the high-riskcategory, risk due to helping employees during an accident index 9.60, very high-risk category, risk due tousing personal protection index 5.83, moderate risk category, risk due to explanations related to safety andhealth. index 6.36, moderate risk category, risk due to explanation sand excavation technique index 4.47,moderate risk category. The average index risk index is 8.99 including high risk. In the activities of sandmining workers and construction work activities, they must first identify and analyze the level of risk.

Exploring the Later Stone Age at a micro-scale: New high-resolution excavations at Wonderwerk Cave

In 2018, we initiated renewed excavation of the Later Stone Age (LSA) deposits at Wonderwerk Cave. Here we describe the goals and initial results of the first two seasons of excavation, including the first micromorphological description of these deposits. We employed a small-scale excavation technique to emphasize precision recording and limit the destruction of sensitive deposits. Our preliminary results indicate that meaningful patterns in material culture records and paleoecological proxy materials can be derived from such investigations.Bioturbation of the LSA deposits is widespread in our micromorphological samples, suggesting that some post-depositional movement of the sediment occurred but did not impact overall stratigraphic integrity. This is supported by the radiocarbon chronology (derived from various material records), which indicates that this movement had a limited effect on the material record.Three technocomplexes (the Kuruman/Oakhurst, Wilton, and Historic) were identified in the new Wonderwerk lithic material record, alongside increasing evidence for a period of intensified use and/or occupation of the site during the Wilton – a pattern previously identified by the F. Thackeray's and A. Thackeray's 1970s excavations. New radiocarbon ages support previous determinations placing the timing of this intensification at ca. 6200 years cal BP.Faunal and ostrich eggshell records also support previous findings, confirming an anthropogenic origin for the faunal remains and suggesting that different pathways of OES bead production were employed at the site at different times. The presence of herbivore dung and associated spherulites in a micromorphology thin section provides a new potential line of evidence to support the Thackeray's tentative suggestion for sheep herding at the site ca. 2000 years BP. While this evidence is far from conclusive, it suggests that the Wonderwerk Cave LSA record may have a role to play in resolving the timing of the adoption of sheep by hunter-gatherers on the Ghaap Plateau.Our work on the LSA at Wonderwerk Cave serves as a touchstone within the more regionally focused Northern Cape Archaeology and Ecology Project (NCAEP) – an international and interdisciplinary research project studying the LSA paleoenvironment of the South African arid interior. Ultimately, NCAEP is designed to produce a multi-proxy diachronic climatic record of the Northern Cape firmly situated within new and existing radiocarbon chronologies.

Eco-archaeological excavation techniques reveal snapshots of subterranean truffle growth

Despite its status as a highly-prized and coveted fungi in gastronomy, many aspects of the subterranean life cycle of the Burgundy truffle (Tuber aestivum) are still unknown, because in situ observations of the formation and maturation of truffle fruitbodies remain difficult. Here, we adopted a suite of archaeological fine-scale excavating techniques to provide unique spatiotemporal snapshots of Burgundy truffle growth at three sites in southern Germany. We also recorded the relative position, fresh weight, maturity level and genotype composition of all excavated fruitbodies. Varying by a factor of thousand, the fresh weight of 73 truffle ranged from 0.1 to 103.2 g, with individual maturity levels likely representing different life cycle stages from completely unripe to fully ripe and even decaying. While only a slightly positive relationship between fruitbody weight and maturity level was found, our results suggest that genetically distinct specimens can exhibit different life cycle stages at the same period of time and under the same environmental conditions. We therefore argue that truffles are likely able to grow, mature and ripe simultaneously between early summer and late winter of the following year. Our case study should encourage further eco-archaeological truffle excavations under different biogeographic settings and at different seasons of the year to gain deeper insights into the fungi's subterranean ecology. The expected cross-disciplinary findings will help truffle hunters and farmers to improve their harvest practices and management strategies.

Deep Excavation Risk Assessment and the Effect of Soil Deformations on Stability of Surrounding Structures.

Construction is crucial to a country's overall economic growth, particularly in developing countries, in the current era of globalization. If construction operations are not carried out strictly according to a local or national building code, they might result in large-scale failures endangering human lives, personnel property, and the economic balance. It is vital to handle the construction process's risk elements. The self-weight of soil and surcharge loading behind the retaining line is the driving force and shear strength of soil is the resisting force as a result, deep excavations invariably cause lateral and vertical ground deformations. As a result of the produced ground deformations, nearby structures and services become kinetically loaded. Risks associated with ground movement cannot be calculated solely using mathematical predicting models and engineering simulations as it needs to address the uncertainty of soil properties, Geo-materials, ground constitutive nature, building stage modeling, three-dimensional impacts of deep excavations, time-dependent natures of ground deformations, and the critical necessity to include human variables such as craftsmanship into prediction models are all important considerations. This article presents a review of the most effective methods for evaluating hazards related to deep excavation and current mitigating techniques. If nonlinear behavior is detected, Finite Element Analysis utilized to do numerical modeling to forecast the behavior of the diaphragm support mechanism and its interaction with the soil mass is presented. Theoretical approaches to enhancing the safety of deep foundation excavation are examined in the context of a hospital building in Khartoum state and a residential district project in southern Jianxi province.

Damage and contour quality in rock excavations for quarrying and tunnelling: assessment for properties and solutions for stability

Excavations in rock masses determine the creation of temporary or final exposed surfaces. Features of these surfaces are depending on both geostructural pattern of the rock mass and adopted excavation method: among the others, roughness, quality of the contour and induced damage inside the rock left in place. These aspects are important as they are requirements expected during the excavation and construction procedures, such those involving dam sidewalls, quarry benches, tunnel profile, slope scaling.This methodological paper describes a list of the possible cases, with a particular emphasis on quarrying and tunneling. By following current modes for profile surveying, the damages are reported, in order to obtain suitable indices for induced damage. Finally the proper techniques for excavation are commented on the basis of real case histories of tunnels and quarries in order to reach the primary objectives of damage reduction and stability/productivity goals.

Analysis of the techniques for assessing the features of blast-induced fragmentation in an open pit quarry

The paper deals with the study of empirical models for the analysis of blasts-induced fragmentation. To verify the reliability of the method, the results obtained a priori through the application of the models are compared with the analyses of muck piles photos taken from a series of blasts in an open pit quarry, thanks to the Split-desktop software (Split Engineering, LLC, Tucson, USA). The study of the particle size distribution is very important when sizing an excavation site, as the average size of the pile must be compatible with the equipment used for clearing and conveyance, and with the first phase of the processing plant, i.e. primary crushing. After a description of the excavation technique in use at the quarry site, its main characteristics are outlined. The parameters used to create the empirical models refer to the geomechanical characteristics of the rock, the geometry of the blasts, the characteristics of the explosive and its interaction with the rock mass, paying attention to the correlation between initiation timing and induced fragmentation. A detailed description of some empirical models together with the Split-desktop software were therefore provided. Thanks to both data and photos of the muck-piles from the exploitation at the quarry, the particle size curves resulting from each model were compared with those obtained from the software. This allowed to validate the empirical method in a preliminary design phase.

Performance of a Large-Scale Excavation by Bottom-Up Technique in Hangzhou Soft Clay

This paper studied the excavation of a foundation pit above a running subway tunnel in Hangzhou soft soil. The zoned excavation and top-down construction techniques were adopted to control the deformation caused by foundation pit excavation. The excavation was divided into four parts, named Zone A, B, C, and D. Zone A adopted temporary diagonal bracing, and the control effect of deformation was poor; it was cancelled and changed to rapid excavation and thicker cushion in Zones B, C, and D. During the whole construction process, the lateral displacement and settlement of the diaphragm wall, surrounding ground surface, and building settlement were monitored and analysed. The data showed that the lateral displacement of the diaphragm wall was effectively reduced by the zoned excavation technique, and the maximum lateral displacement value of the diaphragm wall in Zone A was the least; rapid excavation and reduced soil exposure time also could effectively control the deformation, and the lateral displacement of the diaphragm wall in Zone C is less than Zone B and Zone D. The ground settlement is strongly related to the lateral displacement of the diaphragm wall. In order to reduce the surrounding ground and building settlements, efforts should be made to reduce the wall lateral displacement.

Finding Scepter: assessing European influences in early Swedish shipbuilding and evaluating new excavation techniques

In 2017 the Swedish National Maritime and Transport Museums were commissioned to monitor the excavation at the old shipyard at Skeppsholmen’s quay in Stockholm in case remains were revealed. The shipyard was the biggest workplace in the 17th century. During the excavation a careening dock that was used for the maintenance and repair of large naval ships was first found. It was made of a large number of huge piles. The piles were pulled up and massive ship parts appeared beneath. It turned out to be a large shipwreck in oak. Due to the short time available we tried a new technique. We used a powerful suction digger so as not to damage the roots of trees during excavations. The suction digger helped us to remove the fill material very smoothly and quickly. With this method we managed to uncover large parts of the starboard side. A great number of dendro-samples were taken and it was also possible to conduct detailed archaeological documentation.The identification of the Scepter was made with the support of archaeological observations and dendrochronological samples, confirmed by archival documents. With these results we could see that this ship was indeed the first flagship of King Gustav II Adolf. The ship had a long and exciting history that now could be revealed.This is a fine example of how salvage archaeology together with new techniques can give us new information and great history that was once forgotten.

Van scheepshout tot digitale wrakken. Een reflectie op de ontwikkeling en toekomst van de maritieme archeologie in Nederland

Wooden ships and digital wrecks. A reflection upon the development and future of maritime archaeology in The Netherlands. This paper explores the development of the Dutch maritime archaeological research tradition, the current status of the discipline, and its future perspective. To that end, the focus is mainly on the most important maritime archaeological entity: the shipwreck. Many of the Dutch shipwrecks have been found and studied in the former seabed of the Zuiderzee (the current polders of the province of Flevoland). Ever since the 1940s, shipwrecks have been examined in this region. Until the beginning of the 21st century, many of these wrecks were studied in a more or less traditional (analogue and manual) way. Nowadays, traditional and modern excavation techniques and methods are combined for fast, accurate and detailed research results. We should realize that, whereas the quality of maritime archaeological research will improve over the next 25 years, the preservation quality of the shipwrecks will continue to decrease due to soil disturbance, dehydration and decompression. Therefore, future maritime archaeological developments should focus not only on research techniques, but also on new and better methods that will help to prevent a further deterioration of the Dutch wrecks.

Invention a Paradigm to Discovery the Network Navigation Using Poisson Distribution

Due to increasing the act of Applied science College in Tamil Nadu, the level of competition for admission price is also increased. By implementing some dynamic strategies only the academic introduction s can meet their own competition. One survey clearly commonwealth that more than 75% of the Engineering Colleges their forcefulness is less than thirty % of their actual intake. Hence the surveillance is the job for the insane asylum s. One more survey shows that every year 10% of the applied science college’ windup their affiliation and blessing due to lack of admittance, and 5% of the engineering college have decided to sell due to lack of strength. With the strong effort and dynamic strategy framed by the institution, the nominee finds admission in an institution only when their own orientation matches exactly, otherwise the candidate continues to go by the next alternate in the list of preference [1]. This paper clearly emphasis some factors influenced to identify the pattern for getting the potency of the bookman to meet at least the breakeven point. In plus to the above, the Populace Wide Web in cyberspace plays an important role to store, part and distribute data about the academic innovation. A social survey states that more than 65% of the admissions gained by their effective network pages. The exponential ontogeny of the World Wide Web has provided an excessive prospect to study the potency student and their deportment by using www accession logs. If the institution’s web sphere clearly contains the information required for the potential educate, surely they can attract the above by which they can get more number of admissions even beyond our jurisdiction.[2] Some of the attractions from the potential students while accessing the web site for getting the admission are: get the required information by clicking minimum act of hits from the vane Page, no network traffic occurred while accessing and navigating the college World Wide Web website. Search interrogation will be rectified within a short period of answer time by implementing the practice of search railway locomotive optimization, search engine spiders. Always use fastest and latest browsers and operating systems in their WWW and not to display much more web server erroneousness while navigating the college web site. For attracting the counseling class and other state students, this network Thomas Nelson Page swordplay an important part. World Wide Web usage Mine lying is the practical application of data excavation techniques to very large data deposit to selection pattern radiation diagram. In general every World Wide Web server keeps a record book of all Synonyms/Hyponyms (Ordered by Estimated Frequency) of noun transaction needed for the potential students and act as a bridge between the potential students and introduction. The record contains full phase of the moon contingent about every user click to the entanglement documents of the entanglement site. The useful record 5 senses of detail needs to be scrutinized and inferred to gather knowledge about actual potential student and their parent preferences in accessing www pages. In recent years several method acting s have been proposed for mining web logarithm data. This theme its main intention is to use the statistical method of Poisson statistical distribution analysis to breakthrough out the higher probability session episode and also comparability the efficiency of our developed algorithm with Poisson value. The subject field of large volumes of click stream data demands the employment of data mining method. Conducting data mining on records of web host contains the determination of frequently occurring access sequences. A statistical method of toxicant distribution clearly shows the probability of oftenest of specific consequence when the norm probability of a single natural event is known. Here the probability of poison value is compared with the efficiency of our developed algorithm. For more bit of transactions, our developed algorithm its performance is better than poison value[3].Because our algorithms excerpt the authority tier as dependent rather independent. The Poisson distribution is used in this paper to find out the probability frequency of particular page is visited by the user as independent, but the result of the developed algorithm is dependent

Static and Dynamic Analysis of the Shielded Tunnel in Alluvium Soil with 2D FEM Model

Transportation tunnels are strategic parts of all urban development projects. Challenges are faced while selecting the excavation techniques and support types in these underground constructions. Hence, sufficient information and knowledge are required while designing the shield support system in soft ground tunnelling. In this study, a two-dimensional plane strain finite element simulation of a tunnel having 350-mm thick reinforced concrete liner has been carried out. The effects of soil stratification, degree of saturation, and seismic loading have been considered for the analyses. Mohr-Coulomb’s constitutive model has been adopted to simulate the linear elastic-plastic behaviour of soil in static analysis. Furthermore, the dynamic response of horizontal shear waves (S-wave) has also been investigated on the tunnel’s model. It was observed numerically that the stresses and deformation reduced to 15% and 30% respectively when sandy silt (SM), soil layer moved towards liner in stratification analysis. The tangential and radial stresses increased by 24% and 35%, respectively, due to groundwater presence above the crown. Moreover, vertical and horizontal settlements have increased exponentially that led to a reduction in the shear strength of soil due to variation in water level. Also, ovaling (egging) deformation was observed in the liner due to the propagation of seismic shear waves at the base of the tunnel.

Relationship between Phase Composition and Mechanical Properties of Peat Soils Stabilized Using Oil Shale Ash and Pozzolanic Additive

Construction of road embankments in peatlands commonly involves replacement of the peat with a fill-up soil of an adequate load-bearing capacity. This usually requires a lowering of the water level, turning a peatland from a carbon sink to a source of greenhouse gases. Thus, alternatives are sought that are less costly in both economic and ecological terms. Mass-stabilization technology can provide a cheap substitute for Portland cement. Calcareous ashes (waste materials), supplemented with pozzolanic and alkali additives to facilitate and accelerate the setting and hardening processes, are attractive alternatives to soil excavation or replacement techniques. Silica fume and waterglass were used as pozzolanic agents and KOH as a soil-alkalizing agent. X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses and stress–strain tests were performed for the hardened samples. Crystallization of alkali feldspars was observed in all test samples. Comparable hardening of peat soil was achieved for both ashes. It was shown that the ashes of Estonian kukersite (oil shale) from both pulverized firing and a circulating fluidized bed incineration process (produced in energy sector as quantitatively major solid waste in Estonia) can be used as binding agents for peat stabilization, even without the addition of Portland cement. Hardened peat soil samples behaved as a ductile material, and the cellulose fibers naturally present in peat gave the peat–ash composite plasticity, acting mechanically in the same way as the steel or glass fiber in ordinary reinforced concrete. The effect of peat fiber reinforcement was higher in cases of higher load and displacement of the composite, making the material usable in ecological constructions.

Construction Technique of Vertical Shafts Excavation Above Subway Tunnel

Taking the foundation pit construction of the section K0 + 700 ~ + 900 of Shuangjiehe Road, Tinghai Road and other underground roads in Qianhai District of Shenzhen as an example, this paper introduces a new key construction technology of deep and large foundation pit excavation in the coastal area of reclamation to control the uplift and deformation of underground subway, which effectively utilizes the principle of space–time effect. Based on the number of finite difference software FLAC 3D numerical analysis, the skip excavation method and key construction parameters are simulated and optimized. The monitoring data show that the excavation method, sequence and construction protection measures have significant effect on the deformation control of subway tunnel, which can provide reference for similar projects.

The Efficiency of Large Hole Boring (MSP) Method in the Reduction of Blast-Induced Vibration

Drill and blast is the most cost-effective excavation method for underground construction, however, vibration and noise, induced by blasting, have been consistently reported as problems. Cut blasting has been widely employed to reduce the blast-induced problems during underground excavation. We propose that the large hole boring method using the state-of-the-art MSP (Multi-setting smart-investigation of the ground and pre-large hole boring) machine (“MSP method”) can efficiently improve vibration reduction. The MSP machine will be used to create 382 mm diameter empty holes at the tunnel cut area for this purpose. This study assessed the efficiency of the MSP method in reducing blast-induced vibration in five blasting patterns using a cylinder-cut, which is a traditional cut blasting method. The controlled blasting patterns using the MSP method demonstrated up to 72% reduction in blast-induced vibration, compared to the base case, Pattern B, where only cylinder-cut and smooth blasting method were applied. Therefore, the MSP method proves to be a promising alternative for blasting in sensitive urban areas where non-vibration excavation techniques were initially considered. Geological characteristics of 50 m beyond the excavation face can be acquired through the proposed real-time boring data monitoring system together with a borehole alignment tracking and ground exploration system. The obtained geological information will be a great help in preparing alternative designs, and scheduling of construction equipment and labour during the tunnel construction.

Pharmaceutical Data Search by Decision Trees

The number of information concerning the drugs that any professional of health must control in practice and the transformations which they undergo, make the regulation or the administration of drugs difficult for a pregnant woman. Techniques of excavation of data were developed to lead a model of classification of data according to precise criteria. One of the most used of is the technique of the decision trees, a method making it possible to predict the membership of an individual to a class according to his characteristics; it is based primarily on the relevant attributes of the data base of the field to which it is applied. In our case classification of managed drugs or not with the pregnant woman will be done according to quarters of the pregnancy. The results of this technique will help the professionals of health to take a decision, to make a good regulation, to decrease the accidents related to the catch of inadequate drugs at the period of pregnancy with less risks for the child.

Ilam tunnels inspection, maintenance, and rehabilitation: A case study

Due to the complexities of design and technical issues of construction, tunnels are considered to be enormous financial investments. Therefore, rehabilitation with the purpose of providing a higher life span is essential. Underground facilities usually have a higher service period than expected when designed, which often requires regular inspection. This study aims at providing a guideline for future tunnel investigations and maintenance. Offered solutions with regard to different cases of an anomaly for three available tunnels in the Ilam province have been introduced. These currently servicing tunnels are usually constructed as unlined rock tunnels excavated, using controlled blasting. Masonry, reinforced concrete, and shotcrete lining systems have been used in the collapsible zones. These infrastructures as part of the transportation network of the Ilam province in Iran are located in one of the most active seismic, as well as high rainfall zones in the Middle East. Aging and degradation of material alongside recent earthquake activities can lead to massive destruction of the tunnels if regular maintenance work doesn't take place. All tunnels were evaluated using advanced numerical analysis methods. Stress and displacement values ​​in the rock mass and different lining systems have been investigated using various analytic methods and the rehabilitation programs for tunnels were developed and introduced. The high risk of failure in the tunnel in the Payambar tunnel is predicted in cases of a seismic event affected by the inclination of rock layers. Methods of rehabilitation have been proposed to improve stability and decrease deformations. The formation of icicles in the Azadi tunnel during the cold seasons have been solved through employing a temporary water drainage system. Unlined tunnel sections were planned to be covered with reinforced concrete lining and both cast-in-place and precast segmental lining systems have been proposed. In the Shabab tunnels an extremely disturbed, 2–3 m deep rock layer was found between the masonry lining and the top of the tunnels, due to its controlled blasting excavation technique. Filling the voids using a pressure grouting technique was discovered in order to improve the tunnel stability during an earthquake event.

Piezoelectric-based damage-depth monitoring method for underwater energy-relief blasting technique

Owing to the complex geological conditions and strict excavation shaping and damage control requirements in some underwater engineering applications, the development of a suitable blasting excavation technique has become one of the most difficult technical challenges. The application of Energy-Relief Blasting (ERB) technology to underwater drilling and blasting was first proposed, and a new non-destructive damage assessment method for underwater blasting was also developed. To verify the feasibility of ERB in underwater blasting, two comparative underwater drilling blasting experiments at a depth of 40 m were performed in a water-medium explosion vessel. A pair of piezoelectric ceramic transducers as actuators and sensors to emit and receive the acoustic wave signals, respectively, and thus evaluate the blasting damage induced in concrete specimens. A damage index was defined based on the processed data. The experimental results demonstrated that the ERB technique can effectively control blasting-induced damage in the bedrock. For the specimen with conventional blasting, the depth of damage index greater than 92% is 16 cm, while that of energy-relief technique is only 12 cm, which is 25% less than that of conventional blasting. The experimental results also showed that the active sensing method based on piezoelectric transducers combined with the signal processing method based on the transmitted energy can be used to monitor and quantify the damage induced in the rock mass by underwater drilling blasting.