Micro-piles are reinforced with a steel then poured directly on the ground often with the use of plastic sheets tube or profile or a steel cage made from rebar, while the filler material is made from either cementitious mortar or beton. With this method, after just This fact must be considered during the design phase because the a few months, the roads, squares and gardens on which the work is being evolution, distribution and the final action of the ground also depend on how the support structures deform and how much they deflect.
From this moment on, the only area Bulkheads are generally constructed before excavating the ground to occupied by the site is the access ramp. The floor slabs are anchored to the depth required. The vertical bulkhead is usually installed around the temporary side structures and become self-bearing without building the perimeter of the excavation before placing the topping beams.
The the walls below. The reinforcement tie rods for the poured concrete are ground is then excavated inside the perimeter to the depth of the first row then inserted downwards and bent to shape. After completing all the floor of stays if used , the stays are inserted and then tightened. Excavation slabs, the uprights are then dug out and the concrete is poured in, with work is then carried out level by level, following the same procedure as spaces in the floor slabs where the concrete is poured in.
Reinforcement described above until reaching the depth required. After waiting the standard time before Fig. In so doing, construction work is carried out working downwards until the foundations are reached. Construction work below ground level also represents a chance to be exploited for building auxiliary and service the above, the only solution to adopt to stop water penetrating into the Plate Anchorage zone structures such as car-parks and production units.
Structures below ground level come into contact with the damp in the ground, with water Lowest point of excavation which percolates upwards and with groundwater and, therefore, need to be waterproofed to avoid infiltrations compromising the functionality of the rooms inside such structures. Structures also need to be waterproofed to protect the construction from deteriorating due to the presence of components of the concrete and for the reinforcement rods. Considering Active thrust prism of the ground concrete and infiltrating into the rooms below ground level, is to use a waterproofing system.
When a waterproofing system needs to be installed, the highest point of the groundwater must be considered, whether the level is constant or influenced by temporary events and by the type of ground.
In fact, Fig. With compact, impermeable ground on the other hand, such as clayey ground, the water is released very slowly with the risk of water collecting and generating infiltrations in rooms below ground level. Even when there is no groundwater, the infiltration of rainwater provokes 5. Therefore, from a practical point of view, waterproofing may be installed 5. In fact, even the smallest imperfection cracks, honey combs, etc. There are various phenomena which generate cracks in concrete, In the first case, the waterproofing layer is not subject to high hydrostatic such as shrinkage during curing, seismic activity, settling of foundations loads.
This is mainly due to the formation of the ground, generally formed and vibrations caused by traffic. It is obviously impossible to keep all by sand and gravel, which have good drainage characteristics and, these phenomena under control and be certain that there are no cracks in the concrete after it has been poured. Also, water which penetrates 24 Fig.
This condition may also be achieved on ground with with a layer of natural sodium bentonite sandwiched between the two poor drainage by applying a suitable drainage system at the base of the layers. The needle-punch process Fig. Excavation operations it to the lower support layer of geo-textile fabric.
Thanks to this special modify the intrinsic balance between the ground and the water. After weaving system, the natural sodium bentonite contained in MAPEPROOF completing the construction work and filling in the excavated areas, the remains fixed in place, even after hydration. The special grain size of ground will be considerably less compact and more porous, therefore, the bentonite, together with the type of non-woven geo-textile fabric, compared with the adjacent ground.
This will form a drainage area guarantee saturation of the non-woven fabric which is in contact with towards which the water from the adjacent ground will tend to migrate the poured concrete. This characteristic gives the product an important and generate temporary, high pressures, also due to the fact that the technical advantage: the fabric may be applied after pouring the concrete water is released very slowly.
It is worth remembering that a water head Fig. Therefore, when groundwater is present, even if only than 5 m. The only foundation structure with this capacity is a foundation sheet is so low that it is practically zero. It devitrifies in a watery environment with removal of a part of the silica content.
The White non-woven fabric montmorillonite is then crystallised, and its chemical content depends on are suitable for both new constructions and for repair work on existing the chemical content of the water in which the volcanic ash precipitated. Sodium bentonite expands when it comes into contact available on the Technical Data Sheets for each product and in the with moisture which makes it particularly suitable for sealing purposes Waterproofing Products catalogue.
The upper layer is a non-woven fabric Dark-coloured fabric while the lower layer is a woven fabric. Because of its viscosising properties, mm wide caused by hygrometric shrinkage or settling after pouring the it is used in cement, adhesives, and ceramics and as a binder in the concrete.
It is also used in cosmetics for treating acne and oily skin because of its capacity to absorb excess sebum and clean pores in the skin. Another interesting characteristic of 6. The high As discussed previously, with construction work below ground level in the specific surface area of bentonite and the negative charge of the lamellas presence of ground water, whether it is continuous or due to temporary which form the structure give this mineral the property to absorb and events, the only type of structure capable of withstanding hydrostatic lift adsorb various elements.
As far as durability is concerned, the concrete The mechanism through which bentonite is able to hold water within its must be designed according to EN : , which defines the molecular structure is based on its capacity to swell in the presence of environmental exposition classes Table 1a-b , on the basis of which the water and moisture. Confined, swollen bentonite blocks the passage of limit values are defined Table 2 for the composition and properties of water between the particles Fig.
This stops the water passing through the bentonite and it is trapped inside the crystalline structure. Concrete must be well vibrated to eliminate gravel clusters, and suitable admixes must be included so it fills all the spaces and gaps and flows Fig. In this case, we recommend What actually happens is that, in the presence of water or moisture, the using a super-plasticising admix from the DYNAMON range, produced bentonite forms a waterproof, water-repellent gel. Hydration rates and times vary according to a number of factors, including the grain size of the Porosity of concrete mineral and the surrounding temperature where the phenomenon occurs.
Performance Polymer technology, a new chemical process which, through total monomer design exclusive know-how of MAPEI , allows The waterproofing properties of bentonite laid on site is demonstrated when expansion of the bentonite is blocked by the foundation structure. Concrete made The bentonite hydrates and increases in volume according to the space with products from the DYNAMON range is easy to apply while fresh and available.
This increase in volume, as may be easily imagined, allows the offers very high mechanical performance when hardened. Expanded bentonite obstructs the cavities and saturates cracks up to 3 28 Fig. Concrete with metallic reinforcement or inserts: in very dry surroundings. In buildings with a relatively low level of damp. Concrete without reinforcement inside buildings.
Concrete without reinforcement embedded in non-aggressive ground or water. In many cases, such levels may be considered as the same as the surrounding environment. This may not necessarily be the case if there is a barrier between the concrete and the surroundings. XC1 Dry or permanently wet In buildings with a relatively low level of damp. Conventional reinforced concrete or pre-compressed concrete with the exposed surface in the building, apart from the areas exposed to condensation or immersed in water.
XC2 Wet, rarely dry Parts of structures for containing liquids and foundations. Conventional reinforced concrete or pre-compressed concrete usually immersed in water or non-aggressive ground. XC3 Moderately damp Conventional reinforced concrete or pre-compressed concrete with external surfaces protected from the rain, or inside areas with a moderate to high level of humidity. Natural-finish concrete in urban environments. Surfaces in contact with water not included In class XC2.
Containers and basins for waste water. XA2 Moderate chemically aggressive environment according to Table 2 from EN Structural elements or walls in contact with aggressive ground.
XA3 High chemically aggressive environment according to Table 2 from EN Structural elements or walls in contact with highly aggressive industrial water. Containers for forage, animal feed and sewage. Cooling towers for industrial fumes and discharge gases. XD2 Wet, rarely dry Conventional reinforced concrete or pre-compressed concrete in structural elements completely immersed in water, including industrial water, containing chlorides swimming pools.
XD3 Cyclically wet and dry Conventional reinforced concrete or pre-compressed concrete for structural elements directly subjected to de-icing agents or sprayed water containing de-icing agents. Conventional reinforced concrete or pre-compressed concrete for elements with one surface immersed in water containing chlorides and the other surface exposed to the air. Parts of bridges and floors in carparks. XS2 Permanently submerged Conventional reinforced concrete or pre-compressed concrete for marine structures completely immersed in water.
XS3 Zones exposed to sea-spray or high tides. Conventional reinforced concrete or pre-compressed concrete with structural elements exposed to tidal areas or for zones exposed to sea-spray or waves. Non-vertical surfaces whichh are not completely saturated but exposed to freezing weather, rain or water. XF2 Moderate saturation of water with de-icing agents Elements such as parts of bridges whichh would otherwise be classified as XF1, but whichh are directly or indirectly exposed to de-icing agents.
XF3 High saturation of water without de-icing agents Horizontal surfaces in buildings where water may accumulate and whichh may be subjected to freezing weather and elements subjected to frequent wetting and exposed to freezing weather. XF4 High saturation of water with de-icing agents or with seawater Horizontal surfaces, such as roads and floors exposed to freezing weather and indirectly or directly to de-icing salts, and elements exposed to freezing weather and subjected to frequent wetting with de-icing agents or seawater.
For this class, durability regarding water and aggressive ground must be defined. All the information will be accompanied by specific technical details. When excavation work is carried out, an artificial space is created in which the part of the structure below ground level will be installed.
The hydrogeological balance of the site is modified and, even if there is no groundwater present, after stripping the ground, rainwater and precipitations will collect in the artificial space and form an artificial pond. In such conditions, the structures of the building will have to be made waterproof to protect them from large quantities of water which collects in the area below ground level around the construction.
The waterproofing system is applied by sticking it to the structure foundations and walls with no point left uncovered. There now follows a description of a series of waterproofing interventions to be carried out on site to guarantee that structures below ground level are watertight.
The first intervention which may be necessary to carry out on site, but which is often overlooked, is to waterproof the base of jib cranes when they are positioned in the foundation structure, which should then be followed by waterproofing the lift wells.
Waterproofing of lift wells is often overlooked, and must be carried out before waterproofing the plinth. This should be carried out because, as we will see later, the base of the lift well is usually The method applied to lay MAPEPROOF will be different according to the type of excavation. In the case of excavations without confinement see Section 4 , the bentonite sheets must be hemmed up on formwork. With confined excavations, on the other hand, the sheets must be applied on the containment bulkheads on the side walls of the excavation with one of the following four distinct laying situations: on sheetpiling, piles, micropiles and diaphragms.
In excavations without confinement, waterproofing of the reinforced concrete facing walls is carried out after pouring the concrete. Special care must be taken when sealing around structural joints, elements which pass through the foundation pad and side walls, drainage wells and wellpoint rods. Waterproofing interventions on access ramps below ground level and depuration tanks will be illustrated later.
In the case of foundation pads resting on piles, before preparing the area for laying the bentonite sheets to waterproof the structure, the heads of the piles must be sealed. They must be made watertight to evened out by applying a layer of lean concrete about 10 cm thick.
Position the underside sealing joint and has a section of 20x25 mm. Fasten the characteristics of compactness, flexibility and stability. The swelling Fig. After swelling, which occurs when the product comes into contact with water, IDROSTOP B25 - After laying the system on the vertical surfaces, lay the MAPEPROOF adapts perfectly to the volume defined by the confinement and, thanks on the horizontal surface by positioning the underside the dark side to this special characteristic, perfectly seals both construction joints and of the geo-textile polypropylene fabric on the surface of the lean localised gravel clusters in the cast concrete.
Before applying IDROSTOP concrete and the upper side of the fabric the white side on the vertical B25, carefully clean the surface to eliminate all traces of debris, and surfaces. Overlap the edges of the sheets by at least 10 cm. Fasten the especially the slurry which bleeds from the surface and usually forms when sheets in place on the horizontal surface with nails and MAPEPROOF compacting the cementitious conglomerate.
Below Ground Level. Below Ground Level Book Description:. This book explores the character, use and design of underground space as. More than free eBooks to read or download in english for your Free ebook to download in PDF format - Kb - pages. Books have been you have Now Search this site.
A handweaver's pattern book PDF Online. Angelglass PDF Download. Doctor Marigold. PDF Kindle. The poorly conceived nature of contemporary underground space often means it has little, or no contribution to its above-ground environment, as it neglects the significant relationship between the ground plane, and above and belowground space.
As a result of this omission towards its above-ground environment, urban design theory and practice have neglected the subject of underground space, where it is presented typically as ancillary spaces, of a highly fragmented nature.
This problem is addressed through a literature review, establishing the treatment of underground space within urban design literature, a taxonomy analysis of the physical form of 90 contemporary underground buildings, and a discussion of the five archetypes of underground space. Developed from the findings of each of these research sections, an underground space framework is established. The framework is divided into six guideline categories with which each focusing on a major design issue relevant to underground space.
The presentation of each guideline briefly states the issue, its objective, and then suggests various solutions for implementing the specific objective.
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