Composition Support System Research Articles

Analysis and experiment of a pneumatic-hydraulic composite support system for in-situ mirror processing and testing.

To address the deformation issues caused by the self-gravity and machining stresses in the process of large-aperture mirror fabrication, this paper proposes an in-situ switchable pneumatic-hydraulic hybrid supporting system that enables the seamless transition between machining and testing. By facilitating in-situ switching, this system not only reduces the machining time of large-aperture mirrors, thereby enhancing production efficiency, but also mitigates the risks associated with traditional switching methods that may result in mirror damage due to human error. Three typical working conditions of the hybrid supporting system, namely hydraulic machining support, air-floating testing support, and three-point rigid support, are investigated in terms of mirror loading through a finite element simulation. Additionally, an experimental platform is constructed to validate the proposed system. The experimental results affirm the feasibility of the designed pneumatic-hydraulic hybrid supporting system. This system will serve as a technological support to advance the rapid development of large-aperture space telescope manufacturing techniques.

Monitoring the construction of a deep energy-from-waste bunker in soft clay and peat

This paper describes the monitoring of the construction of a deep underground waste storage bunker for the PROTOS energy-from-waste facility in Chester, UK. A key element of the construction process was a 12 m deep excavation in soft clays and peats which was supported by a complex ‘combi-wall’ cofferdam comprising alternate tube and sheet piles, a reinforced concrete (RC) capping beam and two levels of internal bracing. The permanent bunker RC structure was constructed within the excavation using a bottom-up approach. The primary aim of this monitoring programme was to assess the performance of the composite support system through measured cofferdam wall deflections, bracing member loads, and site and bunker water levels. An additional objective of the monitoring was to provide the site team with real-time feedback to inform the construction process. Interpretation of the monitored data allows for a quantitative assessment of the influence of various construction activities on the responses of the support system. The monitored behaviour shows that the high stiffness and embedment depth of the supporting structure, combined with careful control of groundwater levels, significantly reduced risks associated with deep excavation construction in challenging ground conditions.

Research on the control of overburden deformation by filling ratio of cementing filling method with continuous mining and continuous backfilling.

Underground resource exploitation has seriously damaged the surface ecological environment and underground water system. As an effective control measure, the filling mining process has greatly reduced the surface subsidence. As a branch of the filling mining process, the continuous mining and continuous backfilling (CMCB) method solves the contradiction of mining and filling in this process. The control index of filling ratio of even number lane (FRE) was presented to investigate the technical advantages of the CMCB method. The numerical analysis model was used to investigate the laws such as deformation characteristics of the surrounding rock, stress distribution, and plastic area distribution characteristics of backfill under four typical cases. As a consequence, the FRE effect law on overburden deformation and the roof control function of the backfill was disclosed, and overburden rock deformation control solutions were provided. According to the results, the overburden deformation varies dramatically when the FRE decreases, and it rises greatly when the even-numbered lane backfill (ELB) is not contacted with the roof. The contacting condition and filling condition of the odd numbered lane backfill (OLB) are connected to the distribution of stress and plastic zone. The backfill transmits the rock beam load by building a composite support system with the roof and floor rock layers, and it accomplishes the backfill's roof control function by combining the primary and secondary load-bearing and synergistic load-bearing connections between the backfills. Measures such as differential FRE, differential strength, non-uniformity of filling lane, and synergistic bearing of temporary support and backfill may help to decrease deformations and internal cracks in the surrounding rock. This measure has been successfully implemented in the field, serving as an experience for the application of the CMCB method.

Deformation Control of Subway Stations under the Influence of the Construction of Deep and Large Foundation Pits with Composite Support Systems

The excavation depth of a deep and large foundation pit of a composite support system is 25.5 m, the minimum clear distance from the main structure of the station is 10.6 m and the closest distance to the entrance and exit structure is only 3.6 m. Relying on this project, numerical simulation, field monitoring and other methods are used to study the deformation law of the self-supporting system, the ground settlement and the subway station under construction. Then, the influence of different support parameters on the deformation of the subway station and track is analyzed, and the internal relationship between the deformation value of the station and track and the support parameters is further discussed. The main work and achievements are as follows: (1) Through field measurement and analysis, the deformation history of the station and track in the excavation is studied. The obtained results show that the interbracing + pile–anchor composite support structure has better control over the deformation of adjacent stations and tracks. Comparing the simulated value of station and track deformation with the measured data, it is concluded that the simulated and measured deformation trends remain consistent, and the maximum deformation value corresponds to the middle position of the foundation pit. This confirms the rationality and reliability of the composite support system model. (2) The analysis of the influence of different support parameters on the maximum deformation value of the subway station and track shows that the deformation of the station and track is less affected by the pile diameter of the retaining pile and the size of the interbracing section. It is greatly affected by the embedding depth of the retaining pile and the number of support channels. It is suggested that the optimal parameters should be a pile diameter of 1.0 m, embedding depth of 8 m, four interbracings and an interbracing section of 1.0 m × 1.0 m.

Composite support system for 1.5 T whole-body MRI cryostat

Support system is one of the most critical components of any MRI cryostat in providing the structural integrity during operation and the transportation. We have designed and analyzed the behavior of the composite support structures designed for a 1.5 T MRI cryostat. Various design criteria including the mechanical strength of the composite support system, mechanical resonance frequency of the cryostat, the heat inleak to 4.2 K etc. need to be considered during designing of the composite support system. The dimensional constraints as well as requirements for structural stability and heat conduction to 4.2 K has been established after identification and consideration of problems associated with superconducting magnet support system in MRI. The design incorporates s-glass support straps with intermediate thermal intercepts at 60 K and has been designed to suspend ∼ 5 tons of cold mass. This paper briefly discusses the static and dynamic stress simulation of cryogenic support link of the MRI cryostat using ANSYS. Based on the material choice, the heat leaks down the cold mass support system to 4.2 K and to 60 K are calculated as 250mW and 4.6 W respectively. The spring constant of the support system is 2.79 × 108 Nm-1.

Improved calculation of the rigidity of double-row piles and double-beam composite support and displacement analysis under different soil properties

As a new type of cantilever-type supporting structure, the double-row pile supporting combination system can improve the overall rigidity to maintain the safety and stability of the side of the foundation pit. The case of a double-row pile foundation pit support project in the Wanquan District of Zhangjiakou is taken as an example. Based on the existing double-row pile crown beam stiffness coefficient calculation method, the effect coefficient of the crown beam and the coupling beam is introduced to optimize and improve the effect of the coupling beam and the crown beam. The results show that (1) in the calculation of the double-row pile structure, the common lateral restraint effect of the crown beam and the connecting beam on the double-row supporting piles should be considered, and the rigid connection of the crown beam and the connecting beam should be taken as a whole to improve the rigidity coefficient of the double beam lateral support of a rectangular double-row pile. (2) The combined stiffness of the double-beam combined support system has a greater impact on the displacement of the pile top, and the displacement under a combined stiffness of 40-50 MN/m are close to the observed value. The calculated length of the crown beam and the introduced crown beam and connecting beam effect coefficient have a great influence on the combined stiffness of the double-beam composite support system. The combined stiffness decreases with the increase of the calculated length, and increases with the decrease of the effect coefficient. (3) The lateral support stiffness of the double-row piles under the double-beam composite support system is affected by the difference between the vertical and lateral displacements of the front and rear piles. The maximum lateral displacement of the front and rear piles is affected by the friction angle of the soil, the cohesion and the proportional coefficient of the horizontal resistance of the soil. Changing the tensile strength will not affect the displacement and deformation of the double-row piles. There is a displacement inflection point below the buried depth of the foundation pit and within the scope of the pile bottom. The displacement at the inflection point is equal under different friction angles and different cohesive forces.

Shaking Table Test on the Seismic Responses of a Slope Reinforced by Prestressed Anchor Cables and Double-Row Antisliding Piles

The combined retaining structure has gradually received considerable attention in the slope engineering, due to its good reinforcement effects. However, most of the published research studies were focused on the seismic responses of the single-formal supporting structure only. The investigations of dynamic responses of the combined retaining structures are scarce, and the current seismic design is conducted mainly based on experiences. In this work, a series of large-scale shaking table tests were conducted to investigate the seismic responses of the combined retaining structures (i.e., prestressed anchor cables and double-row antisliding piles) and the reinforced slope under seismic excitations, including amplification effect of internal and surface acceleration of the reinforced slope, distribution and change of prestress of the anchor cable, dynamic response of soil pressure behind the antislide pile, and horizontal displacement of the reinforced slope surface. Test results show that, supported by the reinforcement of composite support system, the slope with the multilayer weak sliding surface can experience strong ground motion of 0.9 g. The load of the antisliding pile has reached 80% of its bearing capacity, and the load of the anchor cable has reached 75.0% of its bearing capacity. When the seismic intensity reaches 0.5 g, the slope surface has an obvious downward trend, which will make the corresponding soil pressure suddenly increase after the antislide pile. At the potential sliding zone, the axial force of the anchor cable will increase suddenly under the action of earthquake; after the earthquake, the initial prestress of the anchor cable will be lost, with the loss range of 17.0%∼23.0%. These test results would provide an important reference for the further study of the seismic performance of such composite support structure.

Designing an innovative support system in loess tunnel

The sufficient early strength of primary support is crucial for stabilizing the surroundings, especially for the tunnels constructed in soil. This paper introduces the Steel-Concrete Composite Support System (SCCS), a new support with high bearing capacity and flexible, rapid construction. The bearing characteristics and construction performance of SCCS were systematically studied using a three-dimensional numerical model. A sensitivity analysis was also performed. It was found that the stress of a π-shaped steel arch decreased with an increase in the thickness of the wall, and increased linearly with an increase in the rate of stress release. In the horizontal direction of the arch section, the nodal stresses of the crown and the shoulder gradually increased in longitudinally, and in the vertical direction, the nodal stresses gradually decreased from top to bottom. The stress distribution at the waist, however, was opposite to that at the crown and the shoulder. By analyzing the stress of the arch section under different installation gaps, the sectional stress evolution was found to have a step-growth trend at the crown and shoulder. The stress evolution at the waist is more likely to have a two-stage growth trend: a slow growth stage and a fast growth stage. The maximum tensile and compressive stresses of the secondary lining supported by SCCS were reduced on average by 38.0% and 49.0%, respectively, compared with the traditional support. The findings can provide a reference for the supporting technology in tunnels driven in loess.

A Simplified Algorithm for Designing Tunnel Composite Support System in Discontinuous Rock Media

Since the introduction of the primary support systems in tunnels, many researchers tried to enhance their composite-like behavior by improving the behavior of structural elements. In this study, the behavior of composite lining with three elements (mesh + frame + shotcrete) was investigated based on the share of each structural element from section’s internal forces using equations derived from shell theory. Then, the result was compared to results of composite section consisting of two elements (frame + shotcrete) in order to determine the role of mesh in bending and axial capacities of composite section. The results showed that mesh element helps the section’s composite-like behavior and increases the bending and axial capacities. Based on this comparison, an algorithm was presented for determining frame spacing as a critical parameter with technical and economical points of view. In this algorithm, an iterative process was introduced to determine lining equivalent section’s properties, inputs for universal distinct element numerical model, based on structural elements, frame spacing and structural analysis methods. The outputs of the numerical method (bending moment distribution, axial force and shear force in the equivalent section) were returned to theoretical model and were compared to structural elements’ capacity diagrams. This process continued until the internal forces reached the range within that of the capacity diagrams. Results indicate that the addition of mesh element reduces the shotcrete’s and steel frame’s share of section’s internal forces. Thus, the steel frame spacing could be increased and the costs of primary support system per meter could be reduced.

Ground load on tunnels built using new Austrian tunneling method: study of a tunnel passing through highly weathered sandstone

The ground load acting on a tunnel is an important issue in tunnel design, especially when the tunnel passes through highly weathered sandstone. A systematic field-monitoring campaign was performed to investigate the ground loads on a tunnel structure, the behavior of the composite support system, and the deformation of the tunnel boundaries. The monitoring results were analyzed and compared with those of various theories, such as the whole-soil column theory and those of Terzaghi, Bierbaumer, Xie Jiaxiu, and Protodyakonov. The ground load on a highway tunnel in highly weathered sandstone does not conform to current theoretical methodologies. It was confirmed that Terzaghi’s theory is suitable for estimating the peak magnitude of the vertical ground load, but differs from the field-monitoring results for ground load distribution profile. To facilitate tunnel design, a potential profile for ground loads is proposed, in which the vertical load component is ‘mountain’-shaped and the horizontal component adopts a ‘folded-line’ pattern. The roof rockbolts are subjected to compression and should be replaced by pipe grouting that is capable of providing enhanced reinforcement and accelerating the construction schedule. The bending moments acting on the lining were found to form a ‘butterfly’ shape. Supplementary finite-element modeling was undertaken to explore the mechanical behavior of the tunnel lining. These results indicated that steel rebar needs to be pre-installed in both the intrados of the lining roof and extrados of the spandrels to improve the lining tensile strength.

作文支援システム「なつめ」における共起表現表示機能と評価

作文支援システム「なつめ」における共起表現表示機能と評価

発達障害のある生徒への情報教育支援を目的とした個別の学習プロセス作成支援システム

発達障害のある生徒への情報教育支援を目的とした個別の学習プロセス作成支援システム

A New Electronic Dictionary with Meaning Description of Case Frame

In this paper, we propose a new electronic dictionary that helps computers to understand languages. In the field of natural language processing, meaning analysis is a difficult problem. The research has been quite few. On the other hand, meaning comprehension is quite interesting and expected to contribute to many fields. For meaning analysis, knowledge about words is indispensable. Thesauruses provide such knowledge by classifying words by their concepts. They can be used as electronic dictionaries. However, the contents are merely the clusters of words. They have little knowledge about the relationships of multiple clusters, resulting in no capacity for grasping relative meaning of words. For this reason, thesauruses are insufficient for meaning analysis. A novel approach is presented in this paper for improving the capability of electronic dictionaries. The contents of the new electronic dictionary are set of nodes and links, the same style as thesauruses. Our method enables computers to treat concretely multiple concepts of words by deriving nodes from another node. Each node consists of a verb and some nouns. Thus, a node-itself can describe meanings as a form of sentence, which differs from thesauruses. Meaning comprehension is achieved by routing nouns through nodes connected with links. Experimental results indicate the excellent ability to analyze meaning of a whole sentence. It is concluded that such ability of the dictionary is quite useful not only as an electronic dictionary itself but also in many fields such as composition support system.

Composites in Shock and Vibration Isolation

The investigation is concerned with the control of force transmitted to the support caused by central normal impact of a projectile on a plate supported by composite isolators with constrained rattle space. Normally isotropic isolators with appropriate low stiffness will absorb appreciable amount of impact energy. But this requires some space (rattle space) for deflection when the plate is subjected to projectile impact. In certain applications (such as plates used as armor in combat aircraft) there is not enough space for the plate to move normal to the plane of the plate. In the present analysis, by using composite isolators the plate is allowed to rotate in the plane of the plate so that less space (rattle space) is required normal to the plane of the plate. By allowing the plate to rotate in its plane, the impact energy is absorbed in the rotational direction in addition to the usual normal to the plane of the plate; thereby transmitting less force to the support compared to the case with isotropic isolators. A method of controlling the force transmitted to the support is to control the natural frequency of the system. In the present analysis the influence of fiber orientation and material properties on the natural frequency of the plate and composite support system is shown.