Initial Excavation Research Articles

Excavation Sequence and Surrounding Rock Mass Stability of Large‐Scale Underground Engineering with 8 Tunnels

In some large‐scale hydroelectric power projects, there are more than 3 tunnels that are too close to each other to eliminate the mutual influence during the excavation period, especially for large‐scale tunnel groups. In this paper, aimed at analyzing the Bukun hydropower station consisting of 8 tunnels in Malaysia, the displacement, stress, and plastic zone of the surrounding rock mass are analyzed to study the effect of the excavation sequence on the stability of the surrounding rock mass for large‐scale tunnel groups. On the one hand, the in situ monitoring of the surface displacement of the rock mass surrounding the tunnel using extensometers is performed to obtain the deformation characteristics on the excavation limit under the typical excavation sequence. On the other hand, a series of elastic‐plastic 3D numerical experiments are carried out to explore the displacement characteristics, stability of the large‐scale tunnel groups, and safety of the initial supporting system. The results show that the tendencies of the displacement increase corresponding to the tunnel face movement are similar for the three excavation sequences. The displacement under initial excavation sequence 2 (IES2) is the smallest among the three sequences; the area of the plastic zone under IES2 is the smallest among them; and the stresses in the shotcrete layer and axial forces in the rock bolt under the three excavation sequences are within the safety limitation. Initial excavation sequence 2 is an optimized excavation sequence, in which tunnels #1 and #5 are excavated first; after an advance of 3 times the diameter of the tunnel, tunnels #3 and #7 are excavated; tunnels #2 and #6 are excavated after an advance of 3 times diameters; and tunnels #4 and #8 are excavated after an advance of 3 times diameters.

A late Middle Pleistocene mammalian fauna recovered in northeast Guangxi, southern China: Implications for regional biogeography

In Guangxi Zhuang Autonomous Region, southern China, Quaternary mammalian assemblages, commonly known as “Stegodon-Ailuropoda fauna”, are well documented in the central and southwest parts of the region. Unfortunately, our knowledge of Quaternary biogeographic variation in other areas of Guangxi is poor due to limited systematic investigations. Here, we report the faunal remains from the newly discovered Diaozhongyan (“DZY”) cave site in northeast Guangxi. Our initial excavation in autumn 2016 resulted in the removal of 10 square meters of sediment and the discovery of 304 pieces of large mammal teeth. Biostratigraphic correlations indicate a late Middle Pleistocene age and in situ fossil teeth and calcites were Uranium-series dated to ~210 ka. The DZY faunal assemblage consists of many typical components of the traditional “Ailuropoda-Stegodon” fauna representative of southern China. Interestingly, giant pandas, identified as Ailuropoda melanoleuca baconi, are one of the dominant components of the DZY fauna (15% of the entire assemblage). However, giant pandas rarely dominate Quaternary faunal assemblages in southern China. In addition, fossil orangutan (Pongo weidenreichi), one of the most common species in central and south Guangxi during the Middle Pleistocene, is absent in DZY in northeast Guangxi. Further, fossil orangutans have not been reported from other sites in Hunan or Hubei province. We hypothesize that the Nanling Mountains served as a geographic barrier for this species. Fossil orangutans are present southwest of this biogeographic line, but are absent northeast of the line. This biogeographic boundary needs to be further evaluated with additional studies.

Effects of different empirical tunnel design approaches on rock mass behaviour during tunnel widening

Empirical based approaches play an important role in tunnel excavation and support system design. These approaches are considered to be very effective in optimising the process of tunnel excavation and particularly tunnel widening. Several reliable empirical approaches have been developed, however the selection or utilisation of an appropriate empirical method for designing the widening of a tunnel is still a challenging task. Therefore, in this work, the analysis of seven different empirical design approaches was carried out to determine the rock mass behaviour during tunnel widening in high in-situ stress state. These approaches include New Austrian Tunnelling Method, Rock Mass Rating, Rock Mass Quality, Rock Mass Index, Rock Structure Rating, Geological Strength Index and Basic Quality Index. On the basis of simulated statistical results obtained from the said empirical approaches, it was found that the application of Rock Mass Quality approach is highly effective in the tunnel widening since it can satisfactorily incorporate the equivalent dimensions and in-situ stress condition of widened tunnel. The method furnishes optimised reinforcement and support design. Additionally, this study also produces reliable data related to the initial excavation of tunnel which can be helpful in defining precise rock mass parameters during tunnel widening.

Effectiveness of the ozone application in two-visit indirect pulp therapy of permanent molars with deep carious lesion: a randomized clinical trial.

The aim of this randomized, three-arm parallel, single-blinded clinical trial was to evaluate the clinical and microbiological effectiveness of the ozone application in two-visit indirect pulp therapy. One hundred five lower first molar teeth with deep caries lesion were included and randomly assigned three groups to apply the two-visit indirect pulp therapy. Treatment procedure was applied without any disinfectant (control), with 60-s 2% chlorhexidine digluconate (CHX) or 60-s ozone application. In four different stages (after initial excavation, ozone/CHX application before the temporary restoration, 4months later immediately after removing temporary restoration, and final excavation), dentin humidity, consistency, and color properties were recorded to evaluate the clinical characteristics of the tissue, and standard dentin samples were collected for the microbiological analysis of mutans streptococci, lactobacilli, and the total number of colony-forming units. The data were analyzed by using Mann-Whitney U test for multiple comparisons. The remaining dentin became harder, drier, and darker after 4months in all groups. However, CHX and ozone application were statistically better than the control group (p <0.05). There was a gradual decrease in the total number of microorganisms in all groups. While cavity disinfectant applications were improved the antibacterial efficacy (control, 79.11%; CHX, 98.39%; ozone, 93.33%), CHX application exhibited a greater significant reduction than both groups (p = 0.000). The two-visit indirect pulp therapy yielded successful results for all study groups. However, CHX would be conveniently preferable due to improving the treatment success. The two-visit indirect pulp therapy applied with cavity disinfectant is a proper alternative treatment procedure in deep carious lesions, instead of conventional technique.

Empowerment and Tech Adoption: Introducing the Treadle Pump Triggers Farmers’ Innovation in Eastern Ethiopia

In 2013, thirty-eight treadle pumps (TPs) were installed as low-cost technology introduction for small-scale irrigation in eastern Ethiopia. This pilot project also trained six farmers on tube well excavation, as well as the installation and maintenance of pumps. In June 2015, researchers visited nine of the thirty-eight TP villages and found only two TPs functioning as originally installed. The rest were replaced with a new technology developed by the trained farmers. Farmers, empowered by training, gained more control in developing technology options tailored to local needs and conditions of their communities. Adopters of the new technology stated that the limited water output and high labor demand of the conventional TP did not optimally fulfil their irrigation water requirements. The new technology had spread quickly to more than one hundred households due to three key factors. First, farmers’ innovative modifications of the initial excavation technique addressed the discharge limitations of the conventional TP by excavating boreholes with wider diameter. Second, local ownership of the new technology, including skills used in well drilling and manufacturing excavation implements, made the modified irrigation technology affordable and accessible to the majority of households. Third, this innovation spread organically without any external support, confirming its sustainability.

Assessing the Integrity of Older Archeological Collections: an Example from La Ferrassie

Initially excavated in the early twentieth century, La Ferrassie is one of the most important sites for the Middle Paleolithic of Western Europe. Aside from the numerous Neanderthal remains found there, the stone artifacts recovered from the site are featured prominently in discussion and debates of Mousterian variability. Recent renewed excavation of the site, however, suggests a considerable preference in the kinds of stone artifacts saved during the initial excavation. Here, we assess the nature and extent of this selection and its effects on the final collection. Results indicate that large, complete, retouched pieces were preferentially retained by the original excavators, and that the artifact collection available for study represents only 2–3% of the original lithic assemblage present in the deposits. This has significant implications for early interpretations of Mousterian industries that were based on such collections and their potential analytical value.

Assessment of ground pressure through soil–structure interaction

The Sydney Metro Northwest involves construction of a fully automated metro rail network in New South Wales, Australia. The underground stations are delivered under two contracts: the Tunnels and Station Civils contract, responsible for the excavation and temporary support, and the Operations, Trains and Systems contract, responsible for the station structures. At the Castle Hill station, the excavation intersects a regional Dural Dome fault, resulting in a rock wedge measuring approximately 20 m high by 80 m long being exposed during excavation. Due to the limited design life of the temporary support, the ground pressure will ultimately be transferred to the station walls. Capturing this, as well as the beneficial effects of the stress relaxation due to the initial excavation, is crucial in achieving an optimised design. This paper presents the integrated ground–structure interaction approach adopted for the permanent walls’ design, which resulted in optimised design ground pressures and station wall thicknesses.

Failure of a Rock Slope Ten Years after Excavation

In the present study, a rock cut slope in Chongqing of China, which failed suddenly about ten years after excavation, was reported. The survey results after failure indicated that the rock masses of the rock slope were highly fractured and heavily weathered, the critical slip surface was composed of three connected discontinuities from the toe to top of slope. The factors resulting in the failure of rock slope were mainly initial excavation and weathering process. The initial excavation removed original supporting role of the excavated rock masses at the toe of the slope to the upper unexcavated rock masses, and broken the original ground stress balance. The physical and chemical weathering after the initial excavation cracked progressively the rock masses, deteriorated the mechanic properties of the rock masses, and changed the stresses and strains in the rock slope. The stability of high artificial rock slope during operation should be paid attention to. The characteristics of geological structure, unloading induced by excavation, and weathering have important effects on the evolution for deformation of artificial rock high slope.

A critical view of Marshall’s Mother Goddess at Mohenjo-Daro

There has been a tendency since the time of initial excavation of Mohenjo-daro by John Marshall to apply some familiar notions about early religions to the finds at Harappan sites, so that clay figurines of women found in various domestic structures were taken to represent the seemingly universal ‘Mother Goddess’. We are now learning that bronze-age ‘religions’ could have assumed immensely varied forms of ritual, belief and physical representations. There could have been varieties of shamanistic or other forms of ritual to ward off evil spirits or sources of harm. The female clay figurines were, therefore, likely to have been home-made representations of women of the house kept to ward off evil forces, rather than being idols of the Mother Goddess, as has been so far largely accepted.

Failure of a rock slope 16.5 years after excavation in repeated strata of sandstone and mudstone

The present study focuses on failure of a rock slope excavated in the autumn of 1997 and located in the repeated strata of sandstone and mudstone in Chongqing of China. The rock slope failed suddenly on April 28, 2014. The elapsed time from excavation to failure is about 16.5 years. The failure was sudden and unexpected seemingly, but it was mainly resulted from the initial excavation and the subsequent weathering in the long term. The initial excavation in 1997 as a reason why the rock cut slope failed was undoubted, because the excavation broke original ground stress balance, resulted in inducement or expansion of cracks and induced deformation and looseness of local rock masses. The weathering process, especially physical weathering process in the long term (16.5 years after excavation), is the most important reason of the failure, because it resulted in disintegration of material on slope surface and induced reduction of strength in the interior of the slope. Water, as a key factor speeding up the weathering process, weakened mechanical properties of rocks and discontinuities and urged formation of argillation intermediate layer. Based on the analyses of failure modes and corresponding factors of safety, an integrated stabilization system on the rock slope was put in place.

Analysis of excavation induced stress distributions of GFRP anchors in a soil slope using distributed fiber optic sensors

In this work, a slope reinforcement system using glass fiber reinforced polymer (GFRP) anchors with pressure grouting was adopted in a field project in Hong Kong. The performance of the GFRP anchor during slope excavation was measured using a novel distributed strain sensing technology, known as Brillouin Optic Time Domain Analysis (BOTDA). The full strain profiles along the GFRP anchor under different excavation stages were obtained using specially protected fiber optic sensors. In addition to fiber optic sensors, traditional strain gauges were installed in the same GFRP anchor. Comparisons show that the BOTDA sensors have good accuracy. In addition, the measured results indicate that the maximum tensile strains and forces occurred at one-third of the GFRP anchor length from the slope surface. The tensile force distribution within the active zone is curvilinear which is confirmed by elastic theory analysis. Shear stress distributions along the GFRP anchors were obtained by differentiating the strain data numerically. The theoretical analysis results were consistent with the measured data at the initial excavation stage. However, the theoretical analysis underestimated the shear stress at the final excavation stage where the slope undergoes plastic deformation. Based on the field measurement results and theory analysis, we conclude that the BOTDA sensing technology provides an alternative and effective approach to identifying distributed strains along anchors and shear zones in reinforced slopes.

Mineralized conduits are part of the uppermost plumbing system of Oligocene methane-seep deposits, Washington State (USA)

Plumbing systems of marine seeps are complex pathways along which hydrocarbon-rich fluids move upward through the sedimentary column. In the shallow subsurface, seep plumbing systems may become successively filled by methane-derived authigenic carbonates resulting in mineralized conduits. This work investigates mineralized conduits in the uppermost plumbing network of Oligocene seep deposits from the Lincoln Creek Formation in Washington State that consist of a paragenetic sequence of authigenic mineral phases. At two study sites the pipes grade into the base of seep deposits. The studied samples of concentrically-mineralized conduits are cylindrical in shape, measure 2–3 cm in diameter, and are up to 15 cm in length; the mineralized conduits are referred to as pipes hereafter. The earliest mineral phase in the paragenetic sequence is matrix micrite, making up the outer part of the pipes. Toward their centers the pipes are filled by two intercalated cement phases, (1) clear, banded and botryoidal aragonite and (2) micro-to cryptocrystalline yellow aragonite. The innermost portions of the pipes are filled by brownish calcite, microspar, or pipe-filling micrite. The observed paragenetic sequences archive successions of biogeochemical processes. The δ13C values of clear and yellow aragonite cements range from −50.6 to −41.2‰, suggesting that their main carbonate source was provided by anaerobic oxidation of methane. In contrast, the later phases (brownish calcite, microspar, pipe-filling micrite) are relatively enriched in 13C (δ13C values: −2.3 to 3.9‰), pointing to carbonate precipitation from fluids affected by methanogenesis. The size and morphology of the pipes suggest that initial excavation was caused by burrowing organisms. The burrows subsequently acted as preferred fluid pathways, suggesting that the transport of fluids within near-surface sediments at the Oligocene seeps was strongly influenced by the activity of the local fauna. Possible producers of the burrows were sediment-dwelling crustaceans, specifically callianassid decapods, as well as bivalves.

Taphonomy of the Tianyuandong human skeleton and faunal remains

Tianyuan Cave is an Upper Palaeolithic site, 6 km from the core area of the Zhoukoudian Site Complex. Tianyuandong (or Tianyuan Cave) yielded one ancient (though not the earliest) fossil skeleton of Homo sapiens in China (42–39 ka cal BP). Together with the human skeleton, abundant animal remains were found, but no stone tools were recovered. The animal fossil remains are extremely fragmentary, in contrast to human skeletal elements that are, for the most part, complete. We undertook a taphonomic study to investigate the circumstances of preservation of the human skeleton in Tianyuan Cave, and in course of this we considered four hypotheses: funerary ritual, cannibalism, carnivore activity or natural death. Taphonomic results characterize the role of human action in the site and how these agents acted in the past. Because of disturbance of the human skeleton during its initial excavation, it is not known if it was in a grave cut or if there was any funerary ritual. No evidence was found for cannibalism or carnivore activity in relation to the human skeleton, suggesting natural death as the most reasonable possibility.

Re-excavation of Dabangay, a mid-Holocene settlement site on Mabuyag in western Torres Strait

The discovery and initial excavation of Dabangay in 2006 established a 7200 year chronology for human settlement on Mabuyag (Mabuiag) in western Torres Strait. This was one of only two Torres Strait sites to pre-date 4000 years ago, providing a rare opportunity to study human activities spanning the mid-to-late Holocene. Remarkable organic preservation and a large mid-Holocene stone artefact assemblage provided insights into long-term continuity and change in lithic technologies and economic strategies; however, results remained preliminary owing to uncertainties about site disturbance. This paper presents results from a second field season of excavations at Dabangay. We suggest chronological association between emerging lithic technologies and altered subsistence practices. Large marine vertebrate bone (present in small quantities from initial settlement), increased after 4200 years ago coincident with increased preference for production of quartz bipolar flakes. A further development after 1800–1600 years ago involved a substantial increase in large and small marine vertebrates and a further increase in the ratio of quartz to igneous lithics.

사질성 지반에서 이수식 쉴드 TBM 적용시 굴진면으로의 이수 침투특성에 대한 해석적 고찰

본 논문은 이수식 쉴드 TBM 굴착시 굴착면 안정에 큰 영향을 미치는 굴착면의 이수 침투에 따른 이막형성여부에 대하여 해석적 고찰을 수행하였다. 이러한 해석적 접근은 이수식 쉴드 TBM의 계획 및 설계시 최적 장비 형식 선정 및 시공계획 수립에 참고가 될 수 있으나, 이제까지 이에 대한 효과적인 해석적 방법에 대하여 제안된 것이 없는 상황이다. 따라서 본 논문에서는 사질토 입자의 모델링에 효과적인 <TEX>$PFC^{2D}$</TEX>의 Fluid Coupling simulation을 이용하여 해석을 수행하였으며, 해석결과, 이수침투 특성은 굴착 대상지반의 투수성과 이수특성(비중, 점성계수등)에 따라 변화됨을 파악할 수 있었다. 본 해석적 접근방법을 통하여 이수식 쉴드 TBM의 계획 설계단계에서 대상지반 특성을 고려한 이수 점도관리 방안 수립과 함께 시공중의 초기굴진단계에서의 최적 이수점도의 재검증을 통하여 안전한 터널시공에 도움이 될 것이라 판단된다. This paper presents numerical analysis of the mud cake infiltration behaviour which is influenced tunnel face stability during excavation by slurry shield TBM. This analysis method can make useful data to select proper shield TBM type and to set up the construction plan. But effective analysis did not proposed until now. In this paper, we carried out numerical analysis using by <TEX>$PFC^{2D}$</TEX> fluid coupling simulation which is suitable for sandy soil modelling. As a analysis result, we checked that the slurry infiltration behaviour varied with soil permeability and slurry characteristic(specific weight, viscosity etc). This analysis method is helpful safety excavation through anticipating the proper slurry viscosity at the design stage and verifying the slurry quality at initial excavation stage.

Tuberculosis Screening before Anti–Hepatitis C Virus Therapy in Prisons

Tuberculosis Screening before Anti–Hepatitis C Virus Therapy in Prisons

Forensic Engineering Investigation Of Failure Of An Oil Pipeline

A Below-Grade, Nps 12 Pipeline Serving A Major Commercial Marine Terminal Failed At A Flanged Joint, Causing A Major Leak And Contamination Of The Surrounding Soil. The Gasket At The Failed Joint Showed Evidence Of Localized, Radial Through-Leakage. At The Terminal, The Initial Excavation Of Contaminated Soil Caused Minor Damage To Several Non-Leaking Segments Of Pipe And The Author Was First Tasked To Oversee The Related Inspection, Weld Repair And Corrosion Protection Work. The Author Subsequently Performed A Forensic Pipe Stress Analysis Of The Affected Portion Of The Fuel Oil System Per The Governing Pressure Piping Code. The Results Indicated That The Leaking Joint Failed With Respect To The Code Criterion Of Equivalent Pressure. Further Investigation Revealed That The System As Originally Designed Was Entirely Of Butt Weld Construction With No Flanged Joints, And Would Have Complied With All Code Requirements. The Investigation Determined That The General Contractor Had Made An Unauthorized Substitution Of Flanged Joints For Butt Weld Joints, Without Informing The Owner Or Design Engineer Of Record.

Çatalhöyük comes Home

The archaeological site of Neolithic Catalhoyuk, on the Anatolian plain in Central Turkey, has been attracting attention since its initial excavation in the 1960s, directed by James Mellaart. Excavation was restarted in 1993, with a new Research Project, directed by Ian Hodder. The archaeology at Catalhoyuk provides a rich record of the minutiae of the daily life of this early farming community which also produced exceptional architecture and art for the period, making it one of the most important archaeological sites in the world. This article presents an overview of the site and the work undertaken to date, weaving in the story of the two project directors and their connetion with the UCL Institute of Archaeology.

Initial excavation and dating of Ngalue Cave: A Middle Stone Age site along the Niassa Rift, Mozambique

Direct evidence for a systematic occupation of the African tropics during the early late Pleistocene is lacking. Here, we report a record of human occupation between 105–42 ka, based on results from a radiometrically-dated cave section from the Mozambican segment of the Niassa (Malawi/Nyasa) Rift called Ngalue. The sedimentary sequence from bottom to top has five units. We concentrate on the so-called “Middle Beds,” which contain a Middle Stone Age industry characterized by the use of the discoidal reduction technique. A significant typological feature is the presence of formal types such as points, scrapers, awls, and microliths. Special objects consist of grinders/core-axes covered by ochre. Ngalue is one of the few directly-dated Pleistocene sites located along the biogeographical corridor for modern human dispersals that links east, central, and southern Africa, and, with further study, may shed new light on hominin cave habitats during the late Pleistocene.

Early Villages on the Persian Gulf Littoral: Revisiting Tol-e Pir and the Galehdār Valley

The archaeological site of Tol-e Pir is situated in the Galehdār Valley, in the south of Fars Province. The site was discovered by Sir M. Aurel Stein in 1933 and is the only prehistoric mound on or adjacent to the Iranian coast of the Persian Gulf that has been excavated. Ceramic material from the surface and excavations is similar to material from well dated sites in the highland Kur River Basin and indicate that the site was occupied during the fifth millennium B.C. Tol-e Pir is thus critical for demarcating the distribution of Chalcolithic painted black-on-buff ceramics in south-west and south Iran, characterising the interaction between populations in different environmental zones during the fifth millennium B.C., and also understanding the development of complexity in early village societies. This paper reviews the initial discovery and excavation of the site, presents the results of a recent survey of the mound, analyses the distinctive black-on-buff painted ceramics, introduces sites that have recently been discovered in the region, and delineates the broader environmental and archaeological contexts.