Risk Analysis of Tunnel Construction Scheme Change based on Field Monitoring and Numerical Analysis

Because of the surrounding environment restriction, some sections of the Lanzhou Metro Line 2 were forced to change the original open excavation method to the concealed excavation method. Among them, the ingate is the transitional section connecting the shaft and the cross passage, which is accompanied by the force conversion of the structure during the plan change process, and accidents are prone to occur. Combining this project situation, a construction scheme for turning the shaft from the cross passage into the ingate of mine line was proposed, and the finite element software is used to simulate the scheme. Numerical analysis shows that the stability of the tunnel supporting structure, shaft, and cross passage all meet the design requirements. The final ground settlement caused by the proposed construction method is 7.1 mm, and the settlement of the vault is 11.97 mm. It also turns out that the proposed construction method causes less deformation, and the method can be applied to the construction of the ingate conversion. The rationality of the method and numerical model was further verified by the comparison between the monitored data of surface settlement and vault sinking and numerical simulation results. Finally, the modified concealed excavation method and the original open excavation construction method is compared. It is concluded that the concealed excavation method is superior to the original open excavation method in terms of construction schedule, construction safety, economic benefits, and impact of construction on the surrounding environment. It indicates that it is a good choice to replace the construction method early if necessary. The successful implementation of this project can provide a reference for the design and implementation of similar urban subway projects.

STUDY OF SKULL PHENODEVIATION IN CARPIAN

Studies were carried out to study the morphology of carp with a pug-shaped and normal developed head according to the main exterior indicators, the structure of the axial skeleton and the morphological indicators of the main blood-forming organs. Comparison of the exterior indicators of normal individuals of the carp with individuals with phenodovia «pug-shaped» revealed significant differences between them. Normal carps had an average body weight of 21,7 % more. Indicators of absolute body length, body length to the end of the scaly cover, body girth and body thickness in normal individuals are superior to those of pug-shaped carps. In pug-shaped carp, it was noted that the number of vertebrae in the caudal region of the axial skeleton is less than 4 %. The structure of the trunk and transitional section does not have significant differences. In pug-shaped individuals of carp, the heart and liver could not be measured, since the organs were deformed under the influence of freezing. The heart in normally developed animals had a mass of 0.48 ± 0.06 g. Gill stamens in pug-shaped specimens ranging from 37–51 – less than in normal carps. They have this figure in the range of 46–52 pcs. When measuring the bones of the skull, it was found that in all pug-shaped instances of carp from different bodies of water, there is a big difference in comparison with normally developed carps. Namely, the bone parasphenoid is shortened in relation to the vomer. Paired, these bones form the bottom of the skull and are in fused condition. Whereas in normally developed carps, the opener has a longer length than the parasphenoid. It is this anomaly of the bones of the skull that leads to the shortening of the snout in the fish.

Study of the cuttings transport in stable foam drilling

Based on the special rheological model of foam fluid, the mathematical models of cuttings transport for stable foam drilling in vertical/near vertical sections, the transitional section, and inclined/horizontal sections are established in this paper. The effects of various flow parameters on the cuttings bed thickness in the annulus are analyzed. The results show that inclination, annulus velocity, foam flow rate, and eccentricity are key factors affecting cuttings transport. The thickness of a cuttings bed gradually decreases with the inclination decrease of the highly deviated/horizontal sections. When the inclination is reduced to approximately 60°, the dynamic and static cuttings bed disappears and is substituted by the glide lamella, which consists of cuttings grains. Cuttings grains have various forms of movement on the lower borehole wall. When the inclination is reduced to below 30°, the cuttings are brought out of the well by the stable foam if the returning velocity of the annulus foam is larger than the depositing velocity of the cuttings. The thickness of the cuttings bed gradually decreases with the increase of annulus velocity. The increased foam quality reduces the concentration of annulus cuttings when the annulus velocity is constant and when it reaches a stable status earlier than the foam drilling fluid of lower foam quality. However, the concentration of the annulus cuttings at the final stage is constant. The thickness of the cuttings bed increases with increased eccentricity of the drill stem. When the eccentricity is large, the change of eccentricity has a high effect on the cuttings bed thickness.

Analysis of the Settlement of Roadbed-Culvert Transitional Section in the High Salinity Regions

In this paper, the construction treatment technology for the transition section connecting road and culvert founded on the high salt saturated fine sand is carried out, in which an actual project of a new local railway from XieTieshan to North Hobson in China is the background. Meanwhile,the field monitoring and finite element analysis of the settlement law of the transition section are carried out under different load conditions. The results are of referential significance to the settlement law and design of roadbed-culvert transitional section in high salinity regions.

Effects of CRTS II Unballasted Track on Seismic Response of High-Speed Railway Bridge

Based on properties of high-speed railway bridge and rail system restraints, the rail-bridge model is established by considering CRTS II unballasted track and bridge structure. The results show that the effect of CRTS II system restraints on seismic response for multi-span simply supported girder bridge is greater so the rail-bridge model should be adopted in earthquake response analysis. Due to the effect of longitudinal stiffness of the railway and bridge transitional section such as terminal spine, the more significant is unloading for seismic response of the side piers if the fewer is the number for the rear-structure spans.

Sedimentological, palynological and geochemical studies of the terrestrial Triassic–Jurassic boundary in northwestern Poland

The Kamień Pomorski IG-1 borehole (Pomerania, NW Poland) yields a profile through the Triassic–Jurassic (T–J) transition in continental deposits. An integrated study of the sedimentology, sequence stratigraphy, palynology, biostratigraphy and geochemistry of these deposits has been carried out on the boundary interval, which represents a time of major environmental change. Two lithological units within the transitional section are distinguished: the Lower–Middle Rhaetian Wielichowo Beds of alluvial plain facies, which shows evidence of a semi-arid climate, and the Upper Rhaetian to Lower Hettangian Zagaje Formation, lying above a marked erosional sequence boundary, composed of mudstone-claystone and sandstone deposited in a fluvial-lacustrine environment. Carbon isotope values obtained from palynomaceral separates, and thus reflecting isotopic changes in atmospheric CO2, show significant fluctuations through the Rhaetian; the most conspicuous negative δ13Corgexcursion is correlated with the Rhaetian ‘initial’ excursion and shows two sub-peaks, pointing to short-term carbon-cycle disturbances of lesser magnitude. Above the ‘initial’ negative excursion, there is a positive excursion followed again by more negative values, representing subordinate fluctuation within a positive excursion and is correlated with the T–J boundary. Seventy-two miospore taxa have been determined from the studied T–J transitional section. Two major palynological assemblages have been distinguished: the lower one, typically Rhaetian, named theCingulizonates rhaeticus–Limbosporites lundblandiiassociation, which corresponds to theRhaetipollis–Ricciisporites(=Rhaetipollis–Limbosporites) Zone; and the upper one, typically Hettangian, named theConbaculatisporites mesozoicus– Dictyophyllidites mortoni–Cerebropollenites thiergartiiassociation (with the age-diagnostic pollenC.thiergartii), which corresponds to thePinuspollenites–Trachysporites(= Trachysporites–Heliosporites) Zone. The T–J palynofloral turnover occurred in a humid period and is more conspicuous then palynofloral changes observed in Greenland, the Tethyan domain or other parts of NE Europe. The osmium isotope system is studied herein for the first time from T–J continental deposits and shows marked disturbances similar to those measured in marine deposits and attributed to volcanic fallout. Carbon and osmium isotope correlation and coeval increase in polycyclic aromatic hydrocarbon (PAH) content and darkening of miospores confirm that eruptions of the Central Atlantic Magmatic Province (CAMP) contributed to the perturbances in climate and crisis in the terrestrial biosphere. A series of periodical atmospheric loading by CO2, CH4or alternatively by SO2, sulphate aerosols and toxic compounds is inferred to have caused a series of rapid climatic reversals, directly influencing the ecosystem and causing the Triassic floral crisis. A floral turnover period commenced at the ‘initial’ δ13C excursion, with the onset of CAMP volcanism. Obtained values of initial187Os/186Os between 2.905 and 4.873 and very low iridium content (about 5 ppt) lend no support to a role for an extraterrestrial impact at the T–J boundary event. The position of the ‘initial’ negative carbon isotope excursion about 12 m below the T–J boundary, position of sequence boundaries (emergence surfaces) and other isotope excursions allow reliable correlation with marine profiles, including St Audrie's Bay (UK), Csövár (Hungary) and the GSSP profile at Kuhjoch (Austria).

Lucretius 4.1–25 and the proems of theDe rerum natura

The status of the first twenty-five lines ofDe rerum natura4 has been a matter of critical controversy since the appearance of Lachmann's edition of the poem in 1855. The lines are repeated almost verbatim from book 1 (926–50), and Lachmann refused to believe that Lucretius himself could be responsible for the duplication of such a long passage in such a prominent position. He condemned the repetition magisterially as a signpauperis ingenii et nullius iudicii. The majority of subsequent editors and critics have followed him in attributing the repetition either to an editor or to an interpolator, or supposed that the poet intended eventually to delete the passage from one of the two locations, but was prevented from doing so by his premature death. The problems raised by the repetition are compounded by the transitional section (26–53): the transmitted text is cumbersome and repetitive, and most critics accept Mewaldt's theory that the passage consists of a ‘doublet’, in which two alternative versions of the usual summary and ‘syllabus’ (26–44 and 45–53) have been imperfectly integrated. Mewaldt himself argued that the doublet was the result of a change in the order of books 3 and 4: book 4 was originally intended to follow 2 directly, and lines 1–25 and 45–53 (which summarize the contents of books 1 and 2only) date from this phase of composition. When the poet decided to insert book 3 between 2 and 4, he substituted the longer summary (26–44) and transferred 1–25 to a new location in book 1; but the posthumous editors of the poem failed to carry out the necessary deletions.