Analysis of static and dynamic deformation modulus

This article summarises dynamic deformation modulus correlation with second reload of static plate load test results for an even thickness soil strata layer. An analysis of execution and result interpretation of both static deformation modulus and dynamic deformation modulus is provided also. Different correlations between the two modulus according to different authors are provided. Since dynamic plate load test is not regulated in Lithuania as a soil compaction contron method, a few dynamic plate load tests and static plate load tests were executed in order to compare compaction results. The additional experiments for dynamic plate load tests in different depths were executed which showed that deformation modulus is dependant on depth of test execution, thus it is worthwile to mention to be cautious on compaction results in trenches

Influence of the pile stiffness on the ground slab behaviour

Just as other structural elements, ground slabs are an important unit of a building. It is especially true in the case of buildings, such as logistic centres, for which the primary purpose is storage of various goods. In this kind of buildings, floor slabs usually have high loads. For buildings where truck lifts are used, there are special requirements for flatness tolerance across and along the driving track of truck lifts. Therefore, the floor settlement differences in selected distances are limited. In localities where the soils under the floor slab are weak, they should be replaced or compacted. If these solutions are not possible or economically inappropriate, the slabs have to be supported on piles that must be based on strong deep soils. During the design process, it is very important to assign a proper value of rigidity of the piles. Pile stiffness has an enormous influence on the settlement of the slab as well as on the reinforcement intensity of the slab or even on the slab thickness. This paper presents the methodology for the evaluation of pile stiffness. In addition, it provides recommendations for the calculation of the floor slab on the piles. Calculations and obtained results confirmed the importance of certain design stages

Influence of Calcite Particles on Mechanical Properties of Grouted Sandy Soil

Chemical and mineralogical content of sands has very high influence on uniaxial compressed strength of grouted soils. In this paper influence of calcite particles in sand on mechanical properties of grouted with urea-formaldehyde resin sandy soil is described. Long-lasting experimental laboratory investigations are executed. In result of our investigations we make conclusion, that addition of calcite particles in sandy soil decreased compressed strength of grouted soil specimens observed in time of 3 months.12th international conference “Modern Building Materials, Structures and Techniques” (MBMST 2016

Research of cement additives influence on the properties of soilcrete

The article analyses a possibility of replacing a part of cement with fly ash in jet grouting piles, because the received strength of cement treated grout is much higher than it is necessary for these piles. The paper presents the problems of fly ash utilization, overviews experimental and theoretical works and analyses laboratory tests on the samples of cement treated grout. The conducted experiments involved manufacturing cylindrical cement treated grout samples containing different additives when the diameter of the cylinder is 35 mm, and its height is 70 mm. The experiments on the samples comprising the additives of fly ash were made in sand and clay soils. 25% to 75% of cement was replaced with fly ash in cement treated grout samples tested under compressive strength following 7 days hardening in air

Estimation of axially-loaded bored piles interaction in the design of pile foundation/Centriškai apkrautų gręžtinių polių tarpusavio sąveikos įvertinimas projektuojant polinius pamatus

In Lithuania and many foreign countries traditional approach of replacing the pile group by equivalent raft foundation in order to estimate settlements is used. But now we have another method. H. Poulos [3] described the influence between piles in a pile foundation with the coefficient of interaction, that indicate the pile influence on the neighbouring piles settlement increasing neighbouring pile acted by axial load. General characteristics of Toyoura sand was shown in the table. With this data and two methods of calculation settlement of 5×5 pile foundation was founded (Fig 1) and results are shown in Fig 3. Also Fig 5 shows the effects of non-linearity on the axial load distribution between a piles of 5×5 group embedded in non-cohesive soil. The load distribution is expressed in terms of the ratio of load on pile to the average pile load in the group (N/Nav), and is plotted against the average pile load. The same figure shows how differ results when the normalised pile spacing 3D, 4,5D and 6D. In the case when the normalised pile spacing r/D=3 and pile foundation work in elastic phase the corner piles take 19,5% larger load as the average pile load and central pile take 20,0% smaller load as the average pile load. But after increasing of the average load this difference decreases. This difference also decreases when the normalised pile spacing increases. First Published Online: 30 Jul 201

Soil Behaviour under Deepening Foundations in Reconstructed Buildings

Reconstructing of old buildings, we want to use building space as much as possible. Therefore, the basement’s rooms are adapted as a useful area to employ. Since the height of the basement’s rooms often is too small the floors must be pulled down and where it is necessary the foundations must be deepened using best design decisions. Often is used method of undermining under foundations. Using this method it is necessary to solve the following questions: excavation depth and width; the distance between the excavations which are made at the same time; the influence of different settlement on building structures; methods that reduce the effects of different settlements. The excavations change the distribution of the pressure under the foundations. The excavation depth and width must be calculated considering to the pressure increasing under reconstructing foundations. The pressure must not exceed the bearing capacity of the ground. The settlements are inevitable when the foundations are deepened. As the foundations are deepened by separate sections, settlements are different. Reducing the effects of the different settlements, special design decisions must be used

Geotechnikos kursinio projekto metodikos nurodymai

Leidinyje pateikti pagrindinių pamatų tipų projektavimo principai, pamatų tipo pasirinkimo principai pagal inžinerinių geologinių tyrimų medžiagą, rekomenduojamas kursinio projekto turinys. Mokomojoje knygoje pateikiama sekliųjų ir polinių pamatų projektavimo eiga pagal LST EN 1997-1:2006 bei projektavimui būtini daliniai koeficientai, jų taikymo taisyklės. Vienas skyrius skirtas Lietuvoje plačiai naudojamiems gręžtiniams pamatams

Peculiarity of the foundations deepening in renovated buildings using excavation / Kai kurios rekonstruojamų pastatų pamatų pagilinimo iškasomis problemos ir jų sprendimo metodai

Deepening foundations is often necessary for renovating old buildings. The process is required for several reasons: first, basement rooms are adapted for activity, since the space of basement rooms is not sufficient, and therefore heightening rooms is essential; second, when the walls of the building are cracked, strengthening foundations is needed; third, renovating buildings increases a load onto foundations. Taking into account the above introduced reasons, an appropriate method for changing the construction of foundations must be chosen. Experience shows that, in most cases, ground resistance under building reconstruction is sufficient and foundations may carry a greater load. Before renovation, the exploitation degree of ground strength must be assessed, which may be expressed as a ratio between foundation pressure and ground resistance. Experience also indicates that, in many cases, the strength of the ground is used irrationally. The foundations of the previously built buildings have a low exploitation degree of strength due to the fact that for designing foundations very simple rules have been used. The other reason is that the ground under foundations takes new characteristics due consolidation over a long period of time. In a compacted soil layer, the angle of shear resistance in sands and cohesion in clays increase. Depending on the maintenance period and soils of base building, ground resistance increases from 1.1 to 1.5 times. Building walls frequently have cracks, as a result of unequal settlements of foundations. In this instance, it is necessary to look for ways to increase the bearing capacity of foundations. Therefore, changing the construction of foundations is required. Foundation basics are often deepened using excavations to adapt the basement rooms for activity and strengthen foundations. The use of this method looks at solving the following questions: excavation depth and width; the distance between simultaneously conducted excavations; the influence of different settlements on building structures; methods for reducing the effects of different settlements. Excavations change the distribution of the pressure under foundations, and therefore excavation depth and width must be calculated considering an increase in pressure under the process of reconstructing foundations. Settlements are inevitable when foundations are deepened. Installing stiffness bands in walls is recommended for reducing the effects from different settlements. Stiffness bands are very effective means of reducing the action of different settlements inevitable when making changes in the con-struction of foundations. Another effective way is the use of jet grouting that accelerates the process of deepening foundation basics. The solid of cemented soil is formed under foundations, and therefore this is a safer and more rapid way than conducting excavations and filling them with concrete. The use of jet grouting reduces uneven settlements. Santrauka Renovuojant senus pastatus, labai dažnai tenka gilinti pamatus. Tai daroma dėl kelių priežasčių: pirma, kai norima rūsio patalpas pritaikyti veiklai. Kadangi rūsio patalpų aukštis būna per mažas, tenka aukštinti patalpas; antra, kai pastato sienos dėl nuosėdžių yra supleišėjusios ir būtina stiprinti pamatus; trečia, dėl padidėjusių apkrovų, renovuojant pastatus. Atsižvelgiant į šias priežastis, pasirenkamas būdas, kuriuo keičiama pamato konstrukcija. Dažnai taikomas pamatų pado gilinimo iškasomis būdas. Šiuo atveju būtina spręsti tokius klausimus: iškasų gylį ir plotį; atstumą tarp vienu metu daromų iškasų; papildomų pamatų nuosėdžių dydį ir poveikį pastato konstrukcijoms; būdus, mažinančius nevienodų nuosėdžių pasekmes. Iškasa keičia slėgio pasiskirstymą po pamatu, todėl iškasos gylis ir plotis turi būti apskaičiuotas įvertinant slėgio didėjimą po renovuojamu pamatu. Gilinant pamatus neišvengiami papildomi pamatų nuosėdžiai. Spartinant pamato pado gilinimo procesą iškasomis efektyvu daryti injekcijas. Taikant srautinį injektavimą, po pamatu suformuojamas sucementuoto grunto masyvas. Pamatai gilinami iškasomis ar injektuojant atskirais ruožais, todėl galimi nevienodi nuosėdžiai. Mažinant nevienodų nuosėdžių poveikį, būtini tam tikri konstrukciniai sprendimai. Reikšminiai žodžiai: Pagrindas, pamatas, gilinimas, iškasa, slėgis, laikomoji galia, nuosėdžiai, srautinio injektavimo polia

Pagrindai ir pamatai

Knygoje pateikiama pagrindo vertinimas: gruntų fizinių ir mechaninių savybių nustatymas, gruntų klasifikavimas, pamatų ir pagrindų projektavimas – sekliųjų, polinių ir giliųjų pamatų projektavimas bei įrengimo technologijos, atraminių sienų projektavimo principai, dirbtinių pagrindų įrengimas ir pamatų stiprinimo metodai. Vadovėlis skiriamas studentams, studijuojantiems statybos inžinerijos programą. Knyga bus naudinga antrosios pakopos studijoms, o pateikti pamatų skaičiavimo metodai – konstruktoriams, projektuojantiems pamatus. Pratarmę, 1–8 skyrius parašė J. Medzvieckas ir D. Sližytė. X.X –X.XX poskyrius – R. Mackevičius. Leidinys parengtas ir išleistas už Europos struktūrinių fondų lėšas, jomis finansuojant VGTU Statybos fakulteto projektą „Transporto ir civilinės inžinerijos sektorių mokslo, verslo ir studijų integralumo didinimas (TRANCI V)“, VP1-2.2-ŠMM -09-V-01-00

The engineering method for unifying ground floor slab settlements

For industrial buildings and logistics centres truck lifts are usually used. Therefore, there are special requirements for flatness tolerance of ground floor. The ground floor settlements differences in selected distances are limited. The article reviews the behaviour of soils and the importance of the actual behaviour assessment of soils during the design of floor slab on elastic subgrade. Particular attention is given to the behaviour of floor slab areas above pile foundations that support the building’s columns. Calculation results show the impact of subgrade stiffness on the behaviour of the floor slab, especially in areas above pile foundations, where the stiffness of subgrade is much higher. The article presents a solution for achieving the required level of settlements’ differences in areas where pile foundations for the building’s columns under the ground slab are used. The paper proposes an efficient engineering method to reduce ground slab settlements differences. The results of performed calculations confirm the efficiency of presented method. First published online 23 March 202