Construction Of Passages Research Articles

Incident during construction of an underwater passage by directional drilling

Relevance. This paper considers the issue of construction of underwater passages of trunk pipelines by the directional drilling method using concrete weight coated pipes. This issue is relevant, since at the present moment there is no standards and technical documentation regulating the calculation procedure of the minimum allowable elastic bend radius of a pipeline with concrete coating in a well. There are situations when design institutes made incorrect design decisions as a result, the pipe string got stuck during works. Those incidents led to unnecessary economic expenditures and a delay in the work implementation plan. Aim. To study the issues which related with the sticking of the pipe string during the construction of the underwater passage of the main pipeline by the method of directional drilling; calculate the minimum allowable elastic bend radius of a pipeline with concrete coating and the actual parameters of the pilot drillhole. Objects. An underwater passage of a trunk pipeline constructed by the method of directional drilling. Methods. Study of standards and technical documents on the construction of underwater crossings of main pipelines and an analysis of the incident in which a pipeline with concrete weight coating got stuck. Results. The authors substantiate the calculation of the minimum allowable elastic bend radius of a pipeline with a concrete coating based on the requirements of domestic standards and technical documentation. The authors have calculated this value by an analytical method, based on studies of the bending stiffness of concrete structures by foreign scientists, as well as actual parameters of the pilot drillhole. The obtained results of the studied values were analyzed and a conclusion was given about the causes of the incident associated with the sticking of the pipe string.

Study on Construction and Optimization of the Life-Saving Passage in Building Ruins Based on Numerical Simulation Method

It is a very important task to construct a life-saving passage in building ruins rapidly and scientifically in the process of earthquake rescue. Currently, the virtual scene is built to train rescuers to construct the life-saving passage quickly and scientifically. However, there are problems such as high cost, small quantity, and single form. A new method of constructing building ruins and life-saving passage was proposed based on the combined finite element (FE) and finite-discrete element (F-DE) method and restarted function of LS-DYNA program. First, taking the RC frame structure ruins as research objection, the different types of life-saving passages were constructed. What’s more, a simple and reasonable optimization method of life-saving passage is proposed based on the rescue technologies with the shortest time. Meanwhile, the timing test of four typical rescue technologies was performed considering the influence factors of various rescue situations. Finally, the practicability and validation of the optimization method was verified through comparing with actual earthquake rescue case. The results show that the restart function of ANSYS/LS-DYNA program can construct the life-saving passage rapidly and reasonably, and simultaneously, the optimal method of life-saving passage can give the optimal rescue route intuitively and accurately. The numerical simulation method of construction and optimization of life-saving passages is expected to provide theoretical guidance for rescue drills for on-site earthquake rescue.

НАУЧНО-ТЕХНИЧЕСКОЕ ОБОСНОВАНИЕ СОЗДАНИЯ ПРИГИДРОУЗЛОВЫХ РЫБОХОДНЫХ, РЫБОХОДНО-НЕРЕСТОВЫХ И НЕРЕСТОВЫХ КАНАЛОВ НА Р. ДОН

Purpose: development of a scientific and technical substantiation for the feasibility of construction and technical solutions for fish pass, fish passage and spawning and spawning channels at waterworks. Materials and methods. The empirical basis of the work was the data of the author's surveys and studies of fish passage and fish-passage and spawning channels operating as part of low-head waterworks on the Western Manych and Don rivers, as well as materials and information on the technical substantiation of the projects of the Bagaevsky and Kochetovsky fish-spawning channels. Results and discussion. In the course of achieving the goal and solving the problems of the study, interpretations of special terms were given: fish passage, fish passage and spawning and spawning channels at the waterworks, and the conditions for the use of each of these structures were formulated. The data of field surveys of the Ust-Manych fish passages and the Konstantinovsky fish passage and spawning channels, carried out in 2022, are presented. Schematic diagrams for the construction of waterworks fish passes, fish passages and spawning and spawning channels are proposed, which, with appropriate study, can be adapted to the specific conditions of their creation and function, which is clearly illustrated by the given examples of design solutions for fish passage and spawning channels arranged as part of the Bagaevsky and Kochetovsky waterworks on the river Don. Structural schemes of facilities and elements that ensure the operation of fish pass, fish passages and spawning and spawning channels, including their main components – tracts, inlet and outlet (for fish) overheads (areas) have been developed. Conclusions. The definitions of the special terms: fish passes, fish passage and spawning (spawning and fish passage) and spawning channels are formulated, and the substantiation of the conditions for their use is given. Layout and structural diagrams for the arrangement of fish passage and fish-passage-spawning channels as part of river low-head waterworks are proposed.

An improved model assessing variation characteristics of pore structure of sandy soil thawing from extremely low temperature using NMR technique

During the construction of subway connecting passages in major cities in China, in last decades the artificial freezing method has gradually been becoming one of the most safe and effective methods in excavating saturated sandy soils. This work aims at exploring the changes of pore size and relaxation time induced by temperature change using NMR technology. Sandy soil samples were retrieved from a subway construction site in Beijing. In the laboratory experiments, these samples were loaded by different extremely low temperatures and natural convection thawing. The T2 (i.e., relaxation time) distribution curves and real-time temperature throughout the thawing process were recorded. It was observed that the variation of T2 distribution curves and pore structure changes with temperature may be divided into four stages, i.e., Stage I: spherical and cylindrical pores with radius r = 0.3 nm are formed at temperature lower than −28.0 °C; Stage II: the water adsorbed in pores melts and pore radius increases to the range of 0.3 nm < r < 32.0 nm as temperature increases in the range of −28.0 °C ∼ -0.2 °C; Stage III: capillary water in the pores with radius >32.0 nm melts rapidly as temperature increases in the range of −0.2 °C ∼ 0.7 °C; Stage IV: small amount of pores transform from small-sized absorptive pores and large-sized capillary pores to medium-sized absorptive pores as temperature increases to above 0.7 °C°. The specific threshold temperature and the threshold relaxation time are found as −0.2 °C and 5.17 ms respectively. By quantitatively analyzing the incremental change of T2 distribution curves and the rising temperature, an improved Gibbs-Thomson equation and a Two-Staged model of T2LM-Tmel (the geometric mean of relaxation time - the absolute value of temperature) and T2-Tmel (relaxation time - the absolute value of temperature), which are applicable to NMR technology, were proposed. Based on these results, a new pore structure evolution model of frozen sandy soil thawing from extremely-low temperature was proposed.

Construction of Rigorous Nonadiabatic Passages for Fast Population Transfer

Construction of Rigorous Nonadiabatic Passages for Fast Population Transfer

Study on the control of construction impacts of shield tunnels in close proximity to sensitive buildings

The construction of interchange passages, which are important appurtenances to metro traffic, often has problem of close proximity to existing buildings. This paper takes the shield excavation project of interchange passage at Jinjiadu Station of Hangzhou Metro Line 2 and Line 4 as an example, and aims to study the impact of shield on existing buildings when crossing them in close proximity. The shield excavation area has a minimum clearance of 1.09 m from the bottom of the station, and the twin tunnel cross a total of six lattice piles with a closest distance of 0.176 m. In order to reduce the impact of the shield excavation on the existing buildings, the excavation area was pre-reinforced with permafrost reinforcement protection measures. A 3D finite element model was built to study the deformation of the existing building under the reinforcement measures. By studying the key construction parameters, the results show that in this project a smaller Propulsion pressure and grouting pressure and a larger grouting volume can effectively reduce the impact of construction on the existing building.

Use of artificial ground freezing in construction of cross passages under Suez Canal

AbstractThe Artificial Ground Freezing (AGF) has demonstrated its versatility as an effective approach for both temporary ground stabilization and ground water control in almost all types of saturated soils. This paper describes the use of a closed circuit freezing system in the construction of four cross passages. The passages connect 4.8 km long twin road tunnels that have recently been constructed at depths of up to 60 m under Suez Canal in Ismailia, Egypt. The paper starts by describing the ground conditions at the locations of the cross passages and by presenting the results of laboratory tests conducted on unfrozen, frozen and thawed soil specimens. The main design criteria considered in designing the freezing works are discussed and the freezing and cross passages construction works are described. The frozen body was carefully monitored during the freezing process and construction of passages. Records of the adopted monitoring program are presented and discussed. Significant observations that contribute to effective planning of future freezing works are also presented.

Test and Analysis of Velocity Law of Flowing Water in Stratum of Bottom Contact Passages in Shield River-Crossing Section

The method of combined hole arrangement on both banks and in the middle of the river was proposed for the test and analysis of the flowing water velocity in contact passages at the bottom of the Wulong River in order to address the insufficient reliability of the existing testing method for the flowing water velocity in the bottom stratum and its failure to truly reflect the data and law of the velocity in the stratum of bottom contact passages in the shield section. Meanwhile, the measurement time of each measuring hole has experienced the fluctuation cycle of the water level, enabling the parameters and law of the flowing water velocity obtained from the test to cover the complete spatial and temporal distribution range. Compared with the existing research, the method has a greatly improved data reliability, guiding the freezing reinforcement construction of bottom contact passages successfully. At the same time, the flow distribution law, velocity range and the law of influence of water fluctuation on the flow velocity revealed in this test can provide reference for related engineering projects in the region.

Forecasting the Logistics Demand of Guangxi Beibu Gulf Port

In February 2007, Guangxi Zhuang Autonomous Region People's Government integrated Fangcheng, Qinzhou and Beihai three coastal ports to establish Guangxi Beibu Gulf International Port Group Co., LTD. At this point, Guangxi Beibu Gulf Port integration of three, Guangxi Beibu Gulf Port ushered in a major development opportunity. Guangxi Beibu Gulf Port is one of the important ports in China's coastal cities open to the outside world. It is the meeting point of the three economic circles of South China, Southwest China and ASEAN, and also the most convenient land and sea passage between China and ASEAN countries. With the vigorous implementation of the "Belt and Road" initiative and the construction of new land and sea passages in western China, Guangxi Beibu Gulf Port has become an important gateway and connection point for the implementation of these strategies. Its strategic status keeps rising, and Guangxi Beibu Gulf Port has also developed rapidly. In recent years, how is the port logistics development of Guangxi Beibu Gulf Port? What are the changing rules and trends of its cargo throughput and container throughput? What measures can continuously and effectively promote the port logistics development of Guangxi Beibu Gulf Port? This paper will carry out research and analysis on these problems in order to better promote the healthy development of Guangxi Beibu Gulf Port. Keywords: Logistics demand forecast, Cargo throughput forecast, Container throughput forecast, Weighted moving average prediction method, Guangxi Beibu Gulf Port

In situ monitoring of temperature and deformation fields of a tunnel cross passage in Changzhou Metro constructed by AGF

Artificial ground freezing (AGF) technology characterized by good waterproof performance, wide adaptability, minimal pollution, and other advantages has been widely used in the construction of tunnel cross passages buried in the soft soil layers. Based on the in situ monitoring, the temperature field of the freezing wall and the deformation field around a cross passage are studied in this paper. The results show that the descent speed of the soil temperature is large at the beginning and becomes small gradually, and finally tends to be stable. The frozen cylinders are enclosing in the phase transformation stage of water. The closer to the freezing pipes the soil is, the faster the soil temperature drops. The temperature of the soil inside the freezing wall is lower than that of the soil outside the freezing wall. The frost heave capacity at the center of the cross passage is the largest, so is the growth rate of the frost heave. The results can offer a reference to the design and construction of the cross passages buried in the soft soil areas.

The numerical analysis of the cross passage of large diameter shield tunnel beneath the river

The construction of the cross passages of twin shield tunnel is confronted with high uncertainty and huge risk. Ground freezing method is widely used for passages excavation in sandy ground condition when the tunnel is under the water. Earlier studies usually concerned the effectiveness of the freezing program, such as the space between the the freezing pipes or the temperature variation in the frozen soil. In this paper, the structure force of the cross passage of a large diameter shield tunnel beneath the river is discussed. A 3-dimensional numerical method is described to calculate the stress of the frozen soil and the internal force of the cross passage lining. The critical situations in construction and operation phases and the key mechanical parts are recognized. The safety of the design scheme is checked.

Explicit construction of nonadiabatic passages for stimulated Raman transitions

We propose a scheme which can produce desired nonadiabatic passages for the stimulated Raman transition in three-level systems. The state transfer in the protocol is realized by following the evolution of the dynamical basis itself and no additional coupling field is required. We also investigate the interplay between the present nonadiabatic protocol and the shortcut to adiabaticity. By incorporating the latter technology, we show that alternative passages with less occupancy of the intermediate level could be designed.

Experimental Study of the Behavior of Rectangular Excavations Supported by a Pipe Roof

This paper presents an experimental investigation of the role of pipe-roofs in the improvement of the stability of rectangular excavations constructed using pipe-roof technology. This technology is suitable for the construction of underground passages in crowded areas subjected to high requirements concerning soil settlement and stability during excavation construction. The design of a rectangular pipe-roof excavation required an understanding of the interaction between the soil, the pipe-roof and the excavation. This interaction is complex and plays an important role in the features of the pipe roof excavation. This paper presents a series of 1g physical experimental tests conducted in dry sand soil with an advanced monitoring system, which allows tracking of the soil settlement, the pipe deformation and the soil pressure. Analysis of these tests shows the effective role of the pipe-roof in reducing both the soil settlement and the soil pressure on the excavation. It also shows the influence of pipes on the deformation mechanism of the soil and its evolution from low deformation to the instability phase.

Theoretical and experimental studies of seismic resistance of underground passages

In this article theoretical calculations of the construction of the underground passages under the influence of seismic forces are conducted and refined by a series of experiments. As a result of experimental studies, the authors have clarified the value of the active pressure of the ground on the construction and the active seismic inertial forces, taking into account the design. As a result of theoretical and experimental studies of seismic resistance of underground pedestrian crossings at different ground, areas of stress concentration in these constructions have been determined, which allows these sections to provide anti-seismic beams, which ensures the safety of the constructions to an earthquake or significantly reduce the degree of damage.

Theoretical and experimental studies of seismic resistance of underground passages

In this article theoretical calculations of the construction of the underground passages under the influence of seismic forces are conducted and refined by a series of experiments. As a result of experimental studies, the authors have clarified the value of the active pressure of the ground on the construction and the active seismic inertial forces, taking into account the design. As a result of theoretical and experimental studies of seismic resistance of underground pedestrian crossings at different ground, areas of stress concentration in these constructions have been determined, which allows these sections to provide anti-seismic beams, which ensures the safety of the constructions to an earthquake or significantly reduce the degree of damage.

Reduction of movement resistance force of pipeline in horizontal curved well at stage of designing underground passage

A method has been developed to reduce the resistance to movement of a pipeline in a horizontal curved well in the construction of underground passages using trenchless technologies. The method can be applied at the design stage. The idea of the proposed method consists in approximating the trajectory of the designed trenchless passage to the equilibrium profile. It has been proved that in order to reduce the resistance to movement of the pipeline arising from contact with the borehole wall, the profile of its initial and final sections must correspond, depending on the initial conditions, to the parabola or hyperbolic cosine equation. Analytical dependences are obtained which allow supplementing the methods of calculation of traction effort in trenchless construction for the case when the profile of the well is given by an arbitrary function.

Flexible Engineering Structures from the Corrugated Metal Sheets - Comparison of Costs of Solutions used in the Road Building

The flexible structures from the corrugated metal sheets are used in particular in the road building, especially as passages for animals. Easy and quick assembly, as well as lower realization costs when compared to the traditional solutions increase interest in such structures. Availability and variety of systems allows for searching for solutions which are the best and optimal in the economical range. The article presents the comparison of costs of the basic materials used in various systems of flexible structures from the corrugated metal sheets. In order to determine the costs of the material solutions the data for two systems used in Poland (for construction of the upper passages for animals) since 2008 have been used. The cost estimation for the basic materials required for realization of 1 m2 of the flexible structure from the corrugated steel sheets have been prepared with use of prices obtained directly from the Polish contractors and manufacturers, as well as process included in the quarterly information (Sekocenbud). The difference of prices of materials available on the market allows the investor for selecting the structure depending on the needs and financial possibilities, as well as for achieving some savings. The savings in case of purchasing sheets of identical parameters (thickness, profile characteristics) are from approx. 4% to 8% per 1 m2 of sheet. The connectors in form of bolts M20 cl. 8.8 of various lengths are an expense from 3.00 PLN to 3.50 PLN. Those values may seem low, but taking into consideration amounts connected with construction of many square meters of structure they may become very important factor in the total investment costs.

Freshwater conservation in a fragmented world: Dealing with barriers in a systematic planning framework

Abstract Disruption of longitudinal connectivity poses one of the most important threats to the persistence of freshwater biodiversity worldwide. Longitudinal connectivity plays a key role by facilitating ecological processes, such as migrations or energy transfer along river networks. For this reason, effective conservation of freshwater biodiversity is highly dependent on a capacity to maintain all processes associated with connectivity. Freshwater protected areas are commonly affected by disruptions of connectivity due to human activities and recent approaches to addressing connectivity when identifying priority areas have overlooked the limitations that human perturbations pose to connectivity. Here, a novel approach is presented to address this issue by accounting for the spatial distribution of barriers using Marxan, a tool commonly applied in conservation planning. This approach was first tested on a simulated example and then applied to the identification of priority areas for the conservation of freshwater vertebrates in the Iberian Peninsula (Spain and Portugal). When using this new approach, the number of disrupted connections within priority areas can be significantly reduced at no additional cost in terms of area needed, which would help maintain connectivity among populations of species with low–medium migratory needs. Given the widespread occurrence of barriers in the study region, the improvement in connectivity within priority areas also resulted in the selection of river reaches closer to the headwaters and the river mouth. Focusing on both extremes of the longitudinal gradient might compromise the effectiveness of conservation efforts for long‐distance migratory species, such as the European eel. This inevitably means that additional management measures, such as barrier removal or construction of fish passages, would be necessary to ensure that these species are able to complete their life cycles. The method demonstrated here could be applied to other regions where connectivity is compromised.

Improvement of Pipe Pushing Method

In focus is improvement of hole-making technology by vibro hammer pushing with batch-wise removal of soil core while a pipe is driven in soil under impact loading. The important advantage of the technology is the concurrent pipe driving and soil core removal. The minimal air pressure required to separate a core and transport it along the pipe is determined. The frequency of soil core separation and transport during vibro-hammer driving of pipes in soil has been tested in underground construction of utilities. The tests prove the possibility to cut-down time of trenchless construction of underground passages and to raise the level of mechanization of the operations.

Ecology, efficiency and economy of new technologies. Methods of mud spring and loss prevention in thenchless pipe laying by directional drilling

Environmental risks – mud springs and losses associated with ineffective measures – lead to environment pollution, increased costs of works, poor economic performance and increased number of technical risks of construction of passages. The consumption of bentonite and the volume of grout to be recycled grow, as well as the amount of works on containment of mud springs and recultivation of disturbed lands. Foam systems and discharge headers are considered as means of mud sping and loss prevention.