{"id":9455,"date":"2023-01-09T10:23:57","date_gmt":"2023-01-09T10:23:57","guid":{"rendered":"https:\/\/blog.geostru.eu\/cedimenti-nel-terreno-nella-realizzazione-di-rilevati\/"},"modified":"2023-01-12T13:32:18","modified_gmt":"2023-01-12T13:32:18","slug":"settlements-of-the-ground-in-the-construction-of-embankments","status":"publish","type":"post","link":"https:\/\/blog.geostru.eu\/en\/settlements-of-the-ground-in-the-construction-of-embankments\/","title":{"rendered":"Settlements of the ground in the construction of embankments"},"content":{"rendered":"

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In the design of road and rail embankments on fine-grained or very fine-grained soils, it is necessary to understand the settlements to overland the time.\u00a0 This is because, in the case of water infiltration, the drainage process takes place very slowly in the medium and long term.<\/p>\n

The problem is particularly felt in the sections adjacent to the shoulders of the viaducts and in the expansion of pre-existing investigations for obvious reasons.<\/p>\n

Therefore, the goal is to speed up the process of the settlement course up to the drainage process or strengthen the terrain. Currently, there are various techniques suitable for the above-mentioned purpose: Traditional ones by applying drainage and\/or preloads and land consolidation techniques with the insertion of columnar reinforcements (pillars, deep mixing, jet grouting, stone columns, etc.)<\/p>\n

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Solutions to intervene in the settlements<\/strong><\/h3>\n

The weak mechanical properties of the foundation soils, together with significant loads deriving from the corresponding weight of those detected, can actually induce instability phenomena or lead to large and prolonged settlements, capable of compromising the functionality of the work.
\nTraditional techniques involve the use of vertical drains, possibly combined with a pre-loading phase. The application of the load has the effect of “pressing” the ground removing water.
\nRecently, solutions are proposed that, instead of aiming at accelerating the drainage process, aim to strengthen the soil in anticipation of subsidence that would occur over time: This is the application of rigid cylindrical elements consisting of piles or columns. On the positive side, it isn\u2019t necessary to wait long periods due to the movement of the soil, but the cost increases.<\/p>\n

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Strengthening through foundation pilots<\/h3>\n

In the application of pilots, the loads are transferred to the head of the latter, trying to increase the central distance and reduce the concentration of tangential forces and distortion in detection that could generate irregularities in the road surface.
\nAn alternative to pillars is the introduction into the soil of various materials such as concrete, sand, gravel, grout, etc. combined with several actions such as tapping, drilling, injection, mixing, vibration, replacement, and compaction. They create cylindrical elements, so-called “columnar reinforcements”: deep mixing, jet grouting, stone columns and all variants associated with them.<\/p>\n

[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]Deep Mixing<\/strong><\/p>\n

This involves the mechanical mixing of lime and\/or cement into the soil through a mechanical drill with rotating blades. If the mixture of lime and cement is added as a powder, dry mixing is usually used for saturated clay soils, if it is previously mixed with wet mixing water.<\/p>\n

[\/vc_column_text][\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text]Jet grouting<\/strong><\/p>\n

It consists of injecting liquid mixtures, designed at high speed.\u00a0\u00a0 This process means that there are phenomena of decay, mixing and\/or soil permeability, which, with adhesion and stiffening, produce a cemented soil element of almost cylindrical shape<\/p>\n

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Fig. 1 – The application of jet grouting on embankment road<\/p>\n

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Stone columns<\/strong><\/p>\n

Stone columns are columns of sand and\/or gravel and have the dual property of water drainage and soil stiffening. They are applied through a vibrating probe that penetrates the ground by thickening the surrounding soil and filling the hole with sand and gravel.<\/p>\n

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Fig. 2 – Railway finding recognized on stone columns<\/p>\n

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A different technique for making stone columns, used in Eastern European countries to strengthen foundations [KWIECIEE and SKI, 2008], consists of dynamic compaction of coarse-grained material with the help of a hammer weighing about 10 tons fallen from maximum heights of 15 m. depending on the characteristics of natural soils, it is possible to reach maximum depths of 4-6 m.<\/p>\n

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