Vajumisvaatluste läbiviimine ehitusobjektil

Käesoleva lõputööga anti ülevaade Tallinnas Metalli tänav 5 büroohoone ehitusel seda ümbritsevatele hoonetele tehtud vajumisvaatlustest. Töö oli jaotatud kolme ossa. Töö esimeses osas tutvustati vajumisvaatluste mõistet, selle läbiviimise meetodeid, alusvõrkude rajamist, käikude tasandamist ja täpsuslike nõudeid vajumisvaatlustele. Töö teises osas anti ülevaade tööde praktilisest teostamisest objektil. Käsitleti töö tegemiseks kasutatud vahendeid, objekti ettevalmistust, mõõtmise protsessi läbiviimist ja kameraaltöid. Selles osas käsitleti ka nivelleerimisel tekkinud probleeme. Töö kolmandas osas anti hinnang vajumisvaatluste metoodikale, tulemustele ja hinnati nende usaldusväärsust. Analüüsi käigus selgus, et lihtsustatud tasanduse kasutamine range asemel, muutis mõõtmistulemusi marginaalsel (ligikaudu 0,2 mm) määral, ühe vajumisreeperi puhul tuvastati 5 mm suurune vajumine. Veel selgus, et mõõtmistes tekib käigus keskmiselt +0,6 mm suurune välistingimustest ja inimlikest vigadest põhjustatud süstemaatiline viga ja, et õlgade ebavõrdsus käigus mõjutab mõõtmistulemust marginaalsel (maksimaalselt ligikaudu 0,2 mm) määral. Analüüsiga hinnati, et, ühe horisondiga ja ühesuunalise käiguga mõõtmine tagab, antud käigu ja nivelliiri kasutamisel, mõõtmistulemuste vastamise III vajumisvaatluste täpsusklassi nõuetele 99,73% tõenäolisusega. Järelduseks on, et tehtud vajumisvaatluste metoodika oli sobiv, kuid mitte ideaalne, ja vajumisvaatlused saavutasid nõutud täpsuse.

The topic of the given thesis is „Conducting a Subsidence Observation at a Construction Site“, which observes the subsidence of neighbouring buildings to the construction site at Metalli 5. It is rarely possible to find large, vacant properties, in densely populated areas, therefore new buildings are constructed on existing vacant lots, usually very close to neighbouring buildings. There is a danger, when constructing the new building that its weight on the subsoil or the construction activity (ramming of piles etc.) causes movements in the subsoil of neighbouring buildings, which may cause subsidence. For evaluating the extent of subsidence and the potential damage that may result, as well as determining the need to take preventive measures, an observation of a possible subsidence is required. The topic of procedures for observations is therefore very actual, in densely populated areas. This thesis aims to provide an overview of the process of conducting subsidence observations. Different methods of observing a subsidence are considered and the problems that might arise. The conducting of observations of a subsidence on site is also analysed, as are the results, with the aim of answering the question, do the chosen methods give trustworthy results within the chosen desired class of exactness. The thesis additionally examines, if the conducting of the levelling process, in subsidence observations using a single horizon, as marked in literature, is justified and if the use of simplified levelling over rigid levelling was justified. The work was divided into three parts. The first part of the work introduced the concept of subsidence observations, methods of conducting, creation of grids, levelling of paths and precision requirements of subsidence observations. The second part of the work gave an overview of the practical work done on site. Consideration was given to the means used, site preparation, conducting of the measuring process and camera work. This part also examined the problems that occurred during levelling. The third part of the work was an evaluation of the subsidence observation methods, results and the reliability of the results. The analysis showed that simplified levelling over rigid, changed the measuring results marginally (roughly 0.2 mm), one subsidence benchmark showed sinking of 5 mm. It also became apparent that there is on average a systematic measuring error of +0.6 mm and the inequality of shoulders, has a marginal effect on measuring results (maximally roughly 0.2 mm). The analysis evaluated that a single horizon and one directional measuring ensures that the given measurement and levelling results correspond with the III exactness class of subsidence observations with the probability of 99,73%. It can be concluded that the method of subsidence observations was appropriate, but not ideal and the subsidence observations achieved the required exactness.