Pulling tests for tree support systems: evaluating strength on artificial balled and burlapped trees

High prestressing force stiffness fish belly beam tool type combined internal support system, referred to as IPS construction method, is a new type of internal support structure system for deep foundation pit support, which is developed based on the principle of prestress and aiming at the shortcomings of traditional concrete internal support and steel support through a large number of engineering research and practical application, it is composed of fish belly beam (high-strength and low relaxation steel strand as the upper chord member. H-shaped steel as the stress beam, and H-shaped steel support beam with different length, butt brace, corner brace, column, cross beam, pull rod, triangular joint, preloading and jacking device and other standard components, and prestress is applied to form a plane restressed support system and three-dimensional structure system. Compared with the traditional concrete internal support and steel support, it greatly improves the overall stiffness and stability of the support system. Combined with the remote real-time monitoring system, it can effectively and accurately control the displacement of the foundation pit and greatly reduce the deformation of the foundation pit. This technology has made a major breakthrough in the internal support technology of deep foundation pit support. It is the most advanced internal support technology in the world. In this paper, a 3-D model of fish belly beam foundation pit support system is established completely, the stress characteristics of the support system are analysed by computer intelligent stress monitoring system, and the distribution areas of prestress and internal support stress are summarized, which can be used as a reference for this type of engineering experience in the future.

The result of the search for new technological solutions in the field of support for roadways in coal mines has in recent years been the widespread use of steel arch with rockbolt support systems. The efficiency of these systems is affected among other things by the option of installing rock bolts after the actual driving the mine roadway, the increased load capacity that these systems can support, and their resistance to dynamic weight. Large variation in the way that these steel arch support can be connected using different types of rock bolts necessitates mining research revealing the effectiveness of such solutions. Although the steel arch with rockbolt support system is used in the majority of European coal mines, it is still not possible to apply templates of schemes due to the diversity of geological and mining conditions. Therefore, throughout a period of several years, the authors of this article conducted research in situ under conditions of different schemes related to connecting arched support frames with rock bolts, with only selected results being presented in the article. The measurements of convergence, load supported by the system frame, load supported by the rock bolts, and the stratification of roof rocks were analyzed, carried out in two roadways with yielding steel arch support in which strand bolts were applied. The article also proposes the index for working maintenance nuw, used in preliminarily assessing the stability of a given working with a limited number of data concerning geomechanical conditions. Additionally considered are empirical methods used in Poland for designing steel arch with rock bolt support systems. The results of mine research indicate that strengthening yielding steel support with strand bolts through steel beams maintains the stability of a roadway, even when exposed to the exploitation stress. Aside from the impact of exploitation, deformations of the support system are negligible, despite the fact that the tensile forces acting on the rock bolts can reach values of up to 160 kN. Under favorable geological and mining conditions, support system frames can be spread up to 1.5 m apart when using rock bolts between them. The conducted measurement of convergence during a three year period revealed a compression amounting to a few centimeters. The results obtained by the research fully confirm the effectiveness of combined yielding steel arch with rock bolt support systems under different mining conditions.

Regarding the whole excavation process of the support system of the Southwest Jiaotong University Station of Chengdu Metro Line 6 (the deep foundation pit bored pile + steel support and support system) as the engineering background, this paper studies the deformation rule of the deep foundation pit bored pile + steel support of the sandy pebble foundation. The deformation rule of this support system, the settlement rule of the ground surface outside the pit, and the rule of the uplift of the loose at the bottom of the pit are studied. A key analysis of the positive corner of the foundation pit is conducted, and the rationality of the optimization of the support scheme is evaluated. This paper provides effective guidance for the subsequent deep foundation pit construction and provides a reference for deep foundation pit construction.

Numerical modeling of non-deformable support in swelling and squeezing rock

The true cost of “greening” a building: Life cycle cost analysis of vertical greenery systems (VGS) in tropical climate

Rock mass characterization is a crucial factor in determining a safe design of a tunnel support system. This research is carried out in constructing tunnel DK 99 – DK 100 high-speed railway Jakarta-Bandung, Indonesia. The research includes determining surface and subsurface quality of rock masses based on rock mass classifications of Geological Strength Index (GSI) and the Basic Quality (BQ-System). Both rock mass classifications were then correlated to the Rock Mass Rating (RMR) for the tunnel support system determination. Another support system determination based on the Japanese Society of Civil Engineers (JSCE, 2007) method was also compared. The result showed that the rock masses at the tunnel elevation had very poor to poor quality according to GSI, RMR, and BQ. The rock masses were classified as category class E and DII according to the JSCE competence factor. The recommended tunnel support system based on the RMR are shotcrete, rockbolt, steel set, while those based on the JSCE are shotcrete, rockbolt, steel support, and lining. This paper is expected to provide a better understanding of tunnel construction in weak rock masses, particularly in Indonesia.

Stage-by-stage control effect field analysis of steel material servo enhanced support system on lateral displacement and bending moment during deep basement excavation

Mature trees provide a range of ecosystem services in urban landscapes, represent important wildlife habitat, and impact positively on human wellbeing. However, mature trees are perceived as a risk to people and infrastructure and occupy land suitable for development. Trees are slow to reach ecological maturity and thus difficult to replace when removed. In this study, we: (a) quantified native canopy cover retained during residential development using aerial imagery; (b) identified where native trees are/are not retained within residential developments with a focus on mature trees; and (c) evaluated the effectiveness of current legal mechanisms for protecting native trees during residential development. Native canopy cover was reduced by 49% during residential development. Mature trees had the highest probability of retention within residential developments if they occurred within intact remnant vegetation. A lower probability of retention for mature trees was observed in urban green space, and almost no mature trees were retained in other areas within residential developments, such as residential blocks and road verges. Mature trees had greater probability of retention where the jurisdiction offered some legislative protection. The loss of mature trees during residential development could be reduced with a greater focus on avoiding the removal of existing trees during the planning stage rather than offsetting the impacts elsewhere; and by designing green space within residential developments to ensure adequate separation between mature trees and people and infrastructure.

Strata loading of mine roadway supports

This talk will provide an overview of performance, durability, and applications of metal-supported solid oxide fuel cell and electrolysis cell technology developed at Lawrence Berkeley National Laboratory (LBNL). The unique LBNL symmetric cell architecture design, with thin zirconia ceramic backbones and electrolyte sandwiched between porous metal supports, offers a number of advantages over conventional all-ceramic cells, including low-cost structural materials (e.g. stainless steel), mechanical ruggedness, excellent tolerance to redox cycling, and extremely fast start-up capability. The metal-supported solid oxide cells achieve high performance at 700°C: >1.5 W/cm2 with 3% humidified hydrogen fuel >1.2 W/cm2 with internal reforming of ethanol fuel >2.6 A/cm2 electrolysis current density at 1.3V and 50%steam/50% hydrogen With infiltrated catalysts, there is a tradeoff between initial performance and long-term stability, as extremely high surface area promotes high electrochemical reaction rates, but also provides high surface energy leading to coarsening and facilitates Cr deposition. Recent approaches to mitigating catalyst coarsening and Cr deposition within the cathode include coatings to prevent Cr evaporation from the stainless steel components, and optimization of infiltrated catalyst processing to stabilize the microstructure during operation. The degradation rate has improved to 2.3% kh-1 in fuel cell mode, compatible with the requirements for electric vehicle range extenders. Electrolysis operation, however, results in higher degradation rate. Efforts to identify and mitigate the additional degradation mechanisms in electrolysis mode will be discussed. Scale-up from button cells to 50cm2 is ongoing, and highlights will be presented. In addition to our long-standing development of zirconia-based metal-supported cells, recent exploratory effort has focused on compatibility between stainless steel metal supports and proton-conducting ceramics. Co-sintering of 400-series stainless steel and BZCY-type proton conductors presents a number of challenges, including: Ba evaporation in reducing atmosphere, over-densification of steel at the high temperatures (>1400°C) required for BZCY processing, and migration of Cr and Si from the steel support into the BZCY layers. Feasibility of new approaches to overcome these challenges will be discussed.

There is a constant effort to reconfigure column stabilized semisubmersible unit to meet the challenging demands associated with deep water exploration. Paired column semisubmersible platform is one of the recent column stabilized semisubmersible hull configured to allow top-deck well head compatibility for oil reserves in deep waters. Its unique ability to maintain reduced vertical motion in extreme weather conditions despite its hull size and payload create a high payload to motion ratio, as compare to conventional semisubmersible hulls. This unique feature makes it recommendable for other hull applications in ocean engineering. A study has been carried out to harness this high payload to motion ratio offered by this new hull concept in the development of drilling and production platforms in deep waters, support and foundation systems. Numerical models were developed to understand the semisubmersible hull (dynamics of the reduced vertical motion and its ability to withstand bending and twisting behaviour from extreme wave conditions). Prior to this, a preliminary CFD model was developed in to understand the vortex shedding effect on the arrayed columns. An experimental setup was also put together to understand this motion behaviour, alongside a detailed review of the first model. The motion response of a scaled hull model was studied in a wave tank with a Digital Image Correlation (DIC) system known as Imetrum. To further investigate its application for other ocean depths and support systems, series of hydrodynamic models were developed in ANSYS AQWA with weather conditions as recommended by API, DNV, and ABS. The AQWA model was validated with results recorded by Imetrum system from the wave tank experimental test. The wave forces and moments were studied for different draft sizes and ocean conditions, and their response where checked in ORCAFLEX. A finite element model was finally developed in APDL to understand the nature and effect of stresses from wave, current and wind loads, alongside topside integration. The results obtained from the FE model was use to postulate reinforcement during scantling, for different hull applications. The results for motion response showed favourable heeling moment for smaller draft sizes as recommended by regulatory bodies, but a reconfiguration for heave displacement might be required for smaller draft size. In such case, an increase in pontoon area or an additional heave plate attachment has been recommended. Furthermore, the effect of wavecurrent interactions was observed to create unique motion behaviour for all draft sizes at resonance frequency range. A fluid-structure interaction model of multi-phase flow will be required to understand this behaviour. The stress concentration on the columns generated from hydrodynamic loads was observed to be higher on the inner columns, relative to the outer ones.

In recent years, with the continuous development of the construction industry, the development of high-rise steel structure growth fast in China. At the same time, it is very important to analyze the structure of these high-rise steel Building, especially the seismic performance analysis. In this paper, the authors analyze the seismic performance of high rise buildings by using finite element modeling, dynamic and static analysis. Through the static analysis of steel structure that combined with dead load, live load and wind load, the result shows that when steel support under the force, the maximum node stress mainly appears in the low-end and the ninth layer, which is located in 19, 22 axis node stress is the largest, respectively as 65.9Mpa, 62.6Mpa, it is safety and within the strength limit. The results can provide a theoretical basis for the seismic design of steel structure buildings

Budong-Budong Dam is located on Salulebo River, West Sulawesi Province, and has a diversion tunnel to divert river flow so as not to interfere with construction at the main dam. This diversion tunnel has a D shape which is dimensions 5 m. The Method used in empirically assessing rock mass quality is Rock Mass Rating (RMR) and Japan Society of Civil Engineers (JSCE). The data used are RMR values and rock-type categories. The results show that the diversion tunnel is in lithology tuffaceous sandstone intercalation tuffaceous siltstone and tuffaceous breccias. Weathering degree from slightly-weathered to highly-weathered. The dominance RMR value is 27-53 and rock-category is CII with L massif rock type. The excavation method based on RMR is top-heading and bench and the excavation method based on JSCE is a full-face method with an auxiliary bench cut. Support systems proposed by RMR and JSCE are rock-bolts, shotcrete, and steel sets (steel support). Even though it has been done empirically, it needs to be considered for modeling to be effective and efficient.

Eccentric load bearing performance of high bolt screw (HBS) active joints for prestressed internal supports in the subway excavation

Construction activities in diversion tunnel of dam need to considere the stability of the tunnel which is very important factor for its continuity. In order to become a safe mining method, it is necessary to analyze the tunnel stability and excavation method using drill and blast method. This analysis is based on empirical method, which is approach using rock mass classification and analytical method based on stresses and deformation of rocks. Based on the analysis, there are three types of rocks passed by the diversion tunnel, i.e breccia, sandstone and claystone, with RMR value ranged from 36 to 51, poor rock class to fair rock class, 2,5 – 3 meters span, top heading bench excavation method, rockbolt, and shotcrete support system with thickness between 256 to 334 mm and steel support.