Foot Of Wall Research Articles

Study on Bolt Support Design for Carbonaceous Shale Tunnel of Highway at High Altitude and Cold Region

With the large-scale development of road traffic infrastructure, tunnel construction gradually extends to high-altitude areas such as the Qinghai-Tibet Plateau. Under the influence of environmental and climatic conditions and regional geological tectonic movement, tunnel construction in this area cannot copy the technology and experience of low-altitude areas, and special research work should be carried out in accordance with regional geological characteristics. Based on a tunnel of Gongyu Highway, the bolt support design of high-altitude tunnel is studied by numerical analysis with FLAC3D software. The results show that the arch bolt should be cancelled and the side wall and lock foot bolt should be strengthened in the bolt support of highway tunnel in high-altitude cold area. Then through multi-dimensional comparative analysis, the length, circumferential spacing and setting range of anchor rods in the carbonaceous shale highway tunnel system at high altitude and cold region, as well as the number, direction and length of anchor rods at lock feet are put forward, which provides technical support for the design and construction of the relying projects, and also provides reference for similar projects.

Instability Process of Crack Propagation and Tunnel Failure Affected by Cross‐Sectional Geometry of an Underground Tunnel

The process of crack propagation and tunnel failure is affected by the cross‐sectional geometry of an underground tunnel. In order to quantify the effect of section shape on the process of crack propagation in deep tunnels under high ground stress conditions, a total of four physical models with two cross‐sectional shapes and twelve stress levels were designed and several large‐scale physical model tests were conducted. The results indicated that, when the vertical stress is 4.94 MPa, the length and depth of the cracks generated in the rock surrounding the horseshoe tunnel are about eight times that around a circular tunnel. The position where the circumferential displacement of the horseshoe tunnel begins to be stable is about two, to two and a half, times that around a circular tunnel. After the deep chamber was excavated, continuous spalling was found to occur at the foot of the horseshoe tunnel and microcracks in the surrounding rock were initially generated from the foot of the side wall and then developed upwards to form a conjugate sliding shape to the foot of the arch roof, where the cracks finally coalesced. Discontinuous spalling occurred at the midheight of the side wall of the circular tunnel after excavation, and microcracks in the surrounding rock were initially generated from the midheight of the side wall and then extended concentrically to greater depth in the rock mass surrounding the tunnel. Tensile failure mainly occurred on the surface of the side wall: shear failure mainly appeared in the surrounding rock.

Improving nature experience in cities: What are people's preferences for vegetated streets?

In the current context of strong urban sprawl, it becomes urgent to find urban approaches that simultaneously promote ecological functions and relationships between people and nature in cities. Streets are omnipresent urban elements that can deliver ecosystem services and facilitate people daily interactions with nature. Promoting vegetation in streets can take different forms which have to be combined with people's preferences. Based on photomontages, we assessed people's perceptions and valuations for herbaceous vegetation types associated to various managements and designs of pavements. Using a combination of a local field survey and a French national online survey, we collected a total of 3609 responses representing a large diversity of socio-demographic characteristics. The results of the field survey confirmed those of the online survey. Although there was variability among people valuations, we found that lowly managed pavements with spontaneous vegetation were in average higher valued than highly managed pavements without vegetation. Pavements with spontaneous vegetation were perceived as less kept than pavements without vegetation, but more beautiful and less boring. We found a consensus of high valuations towards pavements containing vegetation integrated in small design interventions (flowers seeded in foot of wall, design of a meadow strip along the pavement), suggesting that people generally accept vegetation with visible signs of human actions or managements. Socio-demographic characteristics partly explained variabilities in photo valuations. As expected, people frequently connected with nature had the highest preferences for vegetated pavements, spontaneous or integrated in designs. These results show that vegetated streets can become daily biodiversity-friendly urban greenspaces appreciated by urban dwellers. We provide recommendations for promoting vegetation in streets that will be useful for politics, urban designers and managers.

The surface composition of Ceres’ Ezinu quadrangle analyzed by the Dawn mission

We studied the surface composition of Ceres within the limits of the Ezinu quadrangle in the ranges 180–270°E and 21–66°N by analyzing data from Dawn's visible and near-infrared data from the Visible and InfraRed mapping spectrometer and from multispectral images from the Framing Camera. Our analysis includes the distribution of hydroxylated minerals, ammoniated phyllosilicates, carbonates, the search for organic materials and the characterization of physical properties of the regolith. The surface of this quadrangle is largely homogenous, except for small, high-albedo carbonate-rich areas, and one zone on dark, lobate materials on the floor of Occator, which constitute the main topics of investigation. (1) Carbonate-rich surface compositions are associated with H2O ice rich crust. Weaker absorption bands of hydroxylated and ammoniated minerals over the carbonate-rich areas can be explained by higher abundances of carbonates at the topmost surface. (2) Dark, smooth lobate materials at the foot of Occator's northeastern wall possibly reveal fresh slumping of phyllosilicate-rich materials with fine grain size, or local enrichment in carbon-rich materials such as tholins. (3) The deeper absorption band depth of OH and NH4, on the rim of several impact craters, is one observation that is consistent with a stratification of the phyllosilicate abundance that has been inferred previously from global investigations.

Study on the Treatment Timing of Large Deformation of the Tunnel in Swelling Rock

When large deformation of the tunnel occurred in the swelling rock, the large deformation treatment will not only greatly delay the construction time, but also lead to instability or even collapse of the tunnel. Selecting the reasonable timing for large deformation initial support replacement can solve this problem effectively. Based on the LiRang tunnel, the deformation and stress of the tunnel in anhydrite were analysed by FLAC software after excavation. Then replace the deformed first liner at different vault settlement value. The displacement and stress of surrounding rock were analysed when the model reaches equilibrium state again. The results showed that stress concentration at the arch wall and arch foot of the tunnel, and the stress release at the vault and invert is very large after excavation. If the large deformation was treatment when the crown settlement of the tunnel reaches 90% ~95% of the final predicted settlement value, the tunnel deformation and the final stress state could be in a small value. This study can provide a reference for the treatment of large deformation in the swelling rock tunnel.

Study on the shear wall structure with combined form of replaceable devices

Structure with replaceable devices is a type of earthquake resilient structure developed to restore the structure immediately after strong earthquakes. Current researches focus on one type of the replaceable device located in the structural part that is most likely to be damaged; however, plastic deformation would not be limited in a specific part but expand to other parts. To concentrate possible damage in shear wall structures, combined form of replaceable devices was introduced in this article. Based on previous studies, combined form of replaceable coupling beam and replaceable wall foot was used in a coupled shear wall. Influences of the dimension and location of the replaceable devices to the strength and stiffness of the shear wall were investigated through numerical modeling, which was verified by experimental data. Performance comparison between the shear walls with one type and combined form of replaceable devices and the conventional coupled shear wall was performed. In general, the shear wall with combined form of replaceable devices is shown to be better energy dissipated, and proper dimensions and locations of the replaceable devices should be determined.

Establishment of lysozyme gene RNA interference systemand its involvement in salinity tolerance in sea cucumber (Apostichopus japonicus)

The lysozyme gene was silenced using RNA interference (RNAi) to analyze the function of lysozyme in sea cucumber under salt stress. The interfering efficiency of four lysozyme RNAi oligos ranged from 0.55 to 0.70. From the four oligos, p-miR-L245 was used for further interfering experiments because it had the best silencing efficiency. Peristomial film injection of p-miR-L245 (10 μg) was used for further interfering experiments. The lowest gene expression, determined by RT-PCR assay, in muscle, coelomic fluid, and parapodium occurred 48 h after p-miR-L245 injection, while that of body wall and tube foot was 96 h and 24 h, respectively. Lysozyme activity in muscle and body wall was significantly lower than the controls. The lowest lysozyme activity in muscle, body wall and parapodium, was found at 48, 72, and 48 h, respectively, which was consistent with the transcription expression of lysozyme. The lowest point of lysozyme activity was at 96 h in coelomic fluid and tube foot, which was laid behind lysozyme expression in transcription level. The expression profile of the lysozyme transcription level and lysozyme activity in the body wall and tube foot increased at 12 h after p-miR-L245 injection before the interference effect appeared. NKA gene expression was expressed at a high level in the positive control (PC) and negative control (NC) groups at 12, 24, and 48 h, while NKA was expressed at low levels in the lysozyme RNAi injection group at 12 and 24 h. The level of NKA gene expression recovered to the level of the PC and NC group at 48, 72, and 96 h after the lysozyme RNAi injection. NKCC1 gene expression was high in the PC and NC groups at 96 h, while the NKCC1 was expressed at a low level 96 h after lysozyme RNAi injection. The results suggest that lysozyme decay involves NKA and NKCC1 gene expression under salinity 18 psμ. The K+ and Cl− concentration after lysozyme RNAi injection was lower than in the PC and NC group.

Shaking table model tests of concrete containment vessel (CCV) for CPR1000 nuclear power plant

Containment vessel of nuclear power plant is the last barrier to prevent the leakage of radioactive materials, so the seismic performance is of high importance. In order to investigate the seismic performance of the CPR1000 prestressed concrete containment vessel (PCCV) structure under design and beyond-design basis earthquake, a 1/20 scale concrete containment vessel (CCV) model was designed and constructed on the shaking table based on the similitude requirements from the Buckingham's π-Theorem. The horizontal and vertical earthquake waves generated from RG1.60 spectrum were selected as the input earthquake waves in the shaking table model test, and the earthquake waves with peak ground acceleration (PGA) 0.2g, 0.3g, 0.4g, 0.5g, 0.7g, 0.9g and 1.2g respectively were loaded step by step until the macroscopic failure occurred in the model containment vessel. The dynamic responses of the model CCV were obtained from the acceleration sensors and resistance strain gages. The model test results showed that the maximum acceleration magnification factor of the model CCV was 1.974 with PGA of 0.2g, which indicated that the CCV had a good seismic-resistant behavior under 0.2g earthquake. Until the second last test case with the horizontal peak earthquake motion of 0.9g (corresponding to 0.9g for the prototype structure), the fundamental frequency of the model CCV only decreased slightly and the maximum tensile strains at all monitoring points were much smaller than the ultimate tensile strain. It meant that the model CCV as a whole was within the elastic range. In the last case (1.2g), the model fundamental frequency decreased steeply. At the same time, the maximum tensile strains at the heel of the cylinder wall far exceeded the ultimate tensile strain and a circle of cracks occurred at the cylinder wall heel. It meant rupture failure had occurred and the cylinder wall heel of the CCV was the weak region. It agreed well with the numerical analysis results and the visual inspection and camera record at the test site. Although a circle of concrete cracks appeared around the cylinder wall foot, the model CCV still remained integral as a whole and neither cracking parts dislocation nor collapse occurred. Because the test model was a plain concrete structure and the model test results should be conservative estimation, it can be concluded that the prototype PCCV for CPR1000 nuclear power plant had sufficient seismic safety margin.

Energy Remediation Combining Insulation Materials Based on Calcium Silicate and Expanded Polymers

Energy rehabilitation of buildings using airtight insulating materials based on expanded polystyrene is often accompanied by the formation of moisture problems in the enclosure wall footing. Moisture progress in the rehabilitated structure is simulated using modern moisture transient models in Delphin software. Combinations of the developed plate thermal insulating materials based on calcium silicate and the conventional thermal insulation panels based on expanded polymer have been designed to address the moisture problems. This article describes the function of this solution during the reconstruction of a house built from full clay bricks with malfunctioning waterproofing in the lower house construction.

Shielding Design for Adjacent, Underground Buildings of a Megavoltage Radiotherapy Facility.

In a radiotherapy facility, safety in areas next to the treatment room can be of concern when irradiating downward due to oblique x-ray transmission through the floor and/or walls, especially in areas immediately adjacent or underground. Even when there is no basement underneath, a usual conservative solution is to build a thick concrete slab as the base for the treatment room. Of course, this implies deeper soil excavation and higher associated costs. As a convenient alternative, the limiting walls can be buried a certain depth below floor level to shield oblique, downward irradiation. Besides, for space considerations, laminated barriers are usually employed, and some additional shielding to the floor may be required (L-shaped barriers). In this work, the author introduces an analytical method for calculating the required wall penetration below floor level or, alternatively, the additional floor shielding for L-shaped barriers, taking into account in either case the attenuation properties of the earth underneath the vault. Interestingly, the required penetration depth for a given wall barrier (primary or secondary), relative to a reference thickness, is only a function of basic attenuation data. Likewise, for a laminated, lead-concrete barrier, the required dimensions depend on the relative amount of lead used for the wall and on the corresponding attenuation data. The shielding design criteria developed in this work to protect underground nearby sites is conservative in nature, yet it yields optimal shield dimensions for wall footing and for wall-floor shielding, avoiding the need to construct oversized concrete slab floors.

Integrated GPR and ERT as Enhanced Detection for Subsurface Historical Structures Inside Babylonian Houses Site, Uruk City, Southern Iraq

Uruk archaeological site, which located in Al-Muthanna Governorate southern Iraq, was investigated by integrated geophysical methods, ground penetration radar (GPR) and electric resistivity tomography (ERT) to image the historical buried structures. The GPR images show large radar attributes characterized by its continuous reflections having different widths. GPR attributes at shallower depth are mainly representing the upper part of Babylonian Houses that can often be found throughout the study area. In addition, radargrams characterized objects such as buried items, buried trenches and pits which were mainly concentrated near the surface. The ERT results show the presence of several anomalies at different depths generally having low resistivities. It is clear that the first upper zone can be found throughout the whole area and it may represent the top zone of the Babylonian houses. This zone is characterized by its dry clay and sandy soil containing surface broken bricks and slag mixed with core boulders. The second one underneath the top shows a prominent lower resistivity zone. It is probably caused by the moisture content that reduces the resistivity. The thickness of this zone is not equal at all parts of the site. The third deeper zone typically represents the archaeological walls. Most of the main anomalies perhaps referred to the buried clay brick walls. The map of the archaeological anomalies distribution and 3D view of the foundations at the study area using GPR and ERT techniques clearly show the characteristics of the Babylonian remains. A contour map and 3D view of Uruk show that the archaeological anomalies are concentrated mainly at the NE part of the district with higher values of wall height that range between 6 and 8 m and reach to more than 10 m. At the other directions, there are fewer walls with lower heights of 4–6 m and reach in some places the wall foot.

Histamine Immunoreactive Elements in the Central and Peripheral Nervous Systems of the Snail, Biomphalaria spp., Intermediate Host for Schistosoma mansoni.

Histamine appears to be an important transmitter throughout the Animal Kingdom. Gastropods, in particular, have been used in numerous studies establishing potential roles for this biogenic amine in the nervous system and showing its involvement in the generation of diverse behaviours. And yet, the distribution of histamine has only previously been described in a small number of molluscan species. The present study examined the localization of histamine-like immunoreactivity in the central and peripheral nervous systems of pulmonate snails of the genus Biomphalaria. This investigation demonstrates immunoreactive cells throughout the buccal, cerebral, pedal, left parietal and visceral ganglia, indicative of diverse regulatory functions in Biomphalaria. Immunoreactivity was also present in statocyst hair cells, supporting a role for histamine in graviception. In the periphery, dense innervation by immunoreactive fibers was observed in the anterior foot, perioral zone, and other regions of the body wall. This study thus shows that histamine is an abundant transmitter in these snails and its distribution suggest involvement in numerous neural circuits. In addition to providing novel subjects for comparative studies of histaminegic neurons in gastropods, Biomphalaria is also the major intermediate host for the digenetic trematode parasite, which causes human schistosomiasis. The study therefore provides a foundation for understanding potential roles for histamine in interactions between the snail hosts and their trematode parasites.

Settlement Uncertainty Analysis for Continuous Spread Footing on Elastic Soil

In conventional design, continuous spread footings are always designed on the basis of their transverse behavior, where the natural variability of soil properties and any uncertainties in the geometrical and mechanical properties of the structure are usually not considered. In order to reveal the effects of these uncertainties and the soil variability on the behavior of spread footings, the longitudinal direction needed to be studied. Numerous mechanical models, which describe the soil-structure interaction as a beam on elastic foundation, were developed. The common parameter between these models is the subgrade reaction coefficient which depends on numerous parameters. In this paper, the FOSM method was used, first on four semi-empirical models which give the subgrade reaction coefficient, and secondly on the analytical solution of a beam from Winkler’s hypothesis including different boundary conditions. Uncertainties in the subgrade reaction coefficient, differential settlement and bending moment were obtained for the following case: continuous wall footing in residential construction, where a low stiffness zone or shrinkage of clayey soil is possible. Results from a global uncertainty analysis demonstrated the major effects of uncertainties in soil modulus; Poisson’s ratio and width of the spread footing on the uncertainty of the subgrade reaction coefficient, and thus on uncertainties of the differential settlement and bending moment. Finally, it was shown that when the soil modulus and geometrical dimensions of the foundations are uncertain and where a zone of weak soil or shrinkage of clayey soils are present, the longitudinal behavior of continuous spread footings for residential construction should also be considered in their design.

In-situ measure to internal stress of shotcrete layer in soft-rock roadway

In order to solve the difficult conditions of soft rock, water-trickling and hard-maintain of main air-return roadway in Tarangaole Colliery, high pretensioned stress and intensive bolt-shotcrete support program was designed and mechanical property of shotcrete layer was specially monitored through utilizing a type of concrete stress meter with oscillating chord after the program was carried out. It was indicated that, due to rock pressure and support resistance, the interior of shotcrete layer would emerge diverse stresses in axial, radial and tangential directions. With time passing internal stresses in three directions, whose average values were −0.061, 0.043 and 0.517 MPa respectively, fluctuated first and then tended to stability slowly. The axial and radial stresses were relatively smaller than tangential stress which was 11, 12 times the two formers respectively. Along the section of roadway, axial and tangential stresses distributed symmetrically and increased gradually from the top of arch to the waist of wall, but reduced at the foot of wall. Radial stresses reduced from the top of arch to the waist of arch first, and then increased in the waist of wall. Axial stresses were tensile substantially, except for stresses in arch vault tending to compressive, but all the radial stresses were compressive. Nevertheless, tangential stresses in the wall were compressive and tangential stresses in the arch were tensile. During the period of roadway excavating, the stress of shotcrete layer was less than its ultimate bearing capacity, with no significant stress concentration. At the end of this article, some suggests are given to shotcrete support design.

Bearing Capacity of Rectangular Footing on Sandy Soil Bounded by a Wall

The present study investigated the behavior of model footings bounded by a wall of different depths and located at different distances from the footing resting on sandy soil. Different parameters are considered, such as relative density of sand, distance from the wall to the edge of footing (d), width of footing (B) and depth of wall (h). Test results show that the presence of the wall affects remarkably the bearing capacity, leading to improvement in the bearing capacity with different percentages according to the distance of the wall from the edge of footing and depth of wall due to the increase in the soil confinement underneath the footing. In loose sand, the largest improvement in bearing capacity for rectangular footings bounded by walls reaches about 34 %, at h/B = 0.5 and d/B = 2. In medium sand, the largest improvement in bearing capacity for these footings bounded by walls reaches about 33 %, at h/B = 0.5 and d/B = 2, while in dense sand, the largest improvement in bearing capacity for rectangular footings bounded by walls reaches about 52 %, at h/B = 0 and d/B = 2. The presence of the wall mitigates the vertical settlement, and reduction in the vertical settlement ranges from 3 to 24 % in all tests depending on the wall depth and its distance from the footing. In loose and medium sand, the maximum effect of the wall on the value of bearing capacity is when the distance between the wall and the footing edge h/B is 0.5, while in dense sand, the maximum effect of the wall on the bearing capacity is when the wall is in contact with the footing edge h/B is zero.

Experimental study on the behavior of strip footing on sandy soil bounded by a wall

Structural skirts are walls fixed to the edges of shallow foundations to improve their bearing capacities. Sometimes, the shallow foundation is bounded by a close obstruction like a wall. The presence of this wall has an effect on the bearing capacity of footing, whose behavior in this case can be similar to a skirted foundation in which a structural skirt is located at one side of the footing. The present study investigates the behavior of model footings bounded by a wall of different depths and located at different distances from the footing resting on sandy soil. Different parameters are considered such as relative density of sand, distance from the wall to the edge of footing, h, width of footing, B, and ratio and depth of wall, d, to width of footing. Test results show that the presence of the wall affects remarkably the bearing capacity, leading to improvement in the bearing capacity with different percentages according to the distance of the wall from the edge of footing and depth of wall, due to the increase in the soil confinement underneath the footing. In loose sand, the largest improvement in bearing capacity for strip footings bounded by walls reaches about 37 %, at h/B = 0.5 and d/B = 2. In medium sand, the largest improvement in bearing capacity for these footings bounded by walls reaches about 25 %, at h/B = 0.5 and d/B = 2, while in dense sand, the largest improvement in bearing capacity for strip footings bounded by walls reaches about 59 %, at h/B = 0 and d/B = 2. The presence of the wall mitigates the vertical settlement; the largest reduction in the vertical settlement ranges from 5 to 160 % in all tests depending on the wall depth and its distance from the footing. In loose and medium sand, the maximum effect of the wall on the value of bearing capacity is when the distance between the wall and the footing edge, h/B, is 0.5 in all shapes of footings.

Study on the Model Test of Tunnel Lining Deformation Characteristic under the Frost Heaving Force

To study the lining deformation characteristic of the cold region tunnel under the frost heaving force, a model test was designed, and the low temperature environment in the tunnel of model was made by refrigeration equipment, the groundwater inside the model was frozen, the lining structure deformation characteristic under the frost heaving force was analyzed. The results show that the lining was distorted under the frost heaving force, the lining strain of the tunnel crown and side wall was greatly, the maximum strain is 122μ, the lining strains of inverted arch and foot of wall was less, the minimum strain is 25μ.

A Vertical Wall Dominated by Acesta excavata and Neopycnodonte zibrowii, Part of an Undersampled Group of Deep-Sea Habitats

We describe a novel biotope at 633 to 762 m depth on a vertical wall in the Whittard Canyon, an extensive canyon system reaching from the shelf to the deep sea on Ireland’s continental margin. We explored this wall with an ROV and compiled a photomosaic of the habitat. The assemblage contributing to the biotope was dominated by large limid bivalves, Acesta excavata (mean shell height 10.4 cm), and deep-sea oysters, Neopycnodonte zibrowii, at high densities, particularly at overhangs. Mean density of N. zibrowii increased with depth, with densities of the most closely packed areas of A. excavata also increasing with depth. Other taxa associated with the assemblage included the solitary coral Desmophyllum dianthus, cerianthid anemones, comatulid crinoids, the trochid gastropod Margarites sp., the portunid crab Bathynectes longispina and small fish of the family Bythitidae. The scleractinian coral Madrepora oculata, the pencil urchin Cidaris cidaris and a species of Epizoanthus were also common. Prominent but less abundant species included the flytrap anemone Actinoscyphia saginata, the carrier crab Paramola cuvieri, and the fishes Lepidion eques and Conger conger. Observations of the hydrography of the canyon system identified that the upper 500 m was dominated by Eastern North Atlantic Water, with Mediterranean Outflow Water beneath it. The permanent thermocline is found between 600 and 1000 m depth, i.e., in the depth range of the vertical wall and the dense assemblage of filter feeders. Beam attenuation indicated nepheloid layers present in the canyon system with the greatest amounts of suspended material at the ROV dive site between 500 and 750 m. A cross-canyon CTD transect indicated the presence of internal waves between these depths. We hypothesise that internal waves concentrate suspended sediment at high concentrations at the foot of the vertical wall, possibly explaining the large size and high density of filter-feeding molluscs.

Deglaciación reciente de Sierra Nevada : Repercusiones morfogénicas, nuevos datos y perspectivas de estudio futuro

During the Little Ice Age a small glacier occupied the Veleta cirque (Guarnón glacier, Sierra Nevada, Spain). The successive melting and disappearance of the glacier during the first half of the 20th century were followed by the construction of talus cones located at the foot of the cirque wall. Debris buried the residual ice body. At present the talus cones are fed by clasts from the cirque wall and show periglacial processes as gelifluction and ice-creep. These are mainly controlled by the persistence of the snow cover. Among the periglacial landforms the rock glacier is the most interesting feature. Therefore, thermal and morphometric monitoring of the rock glacier is undertaken. The obtained results point to a degradation of the alpine permafrost

Analysis of the Influence of Geometrical Thermal Bridges and their Elimination by Using a Composite Material Based on Secondary Raw Materials

This paper describes the problems of geometrical thermal bridges and discusses their relative influence on building heat loss. The paper also deals with the use of composite material based on secondary raw materials for elimination of thermal bridges in wall footing detail and flat roof parapet detail.