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Pit survey
Each developed the pit is undergoing a survey by geologists, after which it is accepted by a commission with the participation of a representative from the customer. The survey of the pit is carried out in order to establish the correspondence of indicators between the already uncovered soils, as well as those adopted in the project according to the results of engineering and geological surveys. The positive result of the pit acceptance is the Pit Survey Certificate. Which is compiled in 4 copies. Architectural and geotechnical supervision, contractor and geological organization, which directly performed the quality certificationsoil in the pit, receive one separate copy.
Act of inspection of open ditches and foundation pits
A method of protecting employees from caves by excavating the sides of the excavation to form one or a series of horizontal levels or steps, usually with vertical or nearly vertical surfaces between the levels. The separation of a mass of soil or rock material from the side of the excavation, or soil loss from under the trench shield or support system, and its sudden movement into the excavation, either by falling or sliding, in sufficient quantity so that it can entrap, bury or otherwise injure and protect the person.
Features of the excavation survey procedure
The survey of the pit begins with a visit to the area by a geological engineer for a preliminary acquaintance with the excavated pit, as well as a description of the soils that were uncovered in its walls. Previously carried out engineering and geological surveys with the developed Technical Report on the study of the territory are the basis for clarifying and detailing new indicators for the excavation. The dimensions and elevations of the pit, its actual bedding, as well as the quality of the soil must match the geological section given in the project. The Commission, also relying on the data on the project, establishes the possibility of laying the foundation slab at the design level or changed for some reason.
Someone who is able to identify existing and foreseeable hazards in the environment or work conditions that could affect employees and the general public, and who has the right to take prompt corrective action to eliminate them. Must be trained and knowledgeable about excavation and trenching standards and other programs that may be applied. Must be able to recognize hazardous conditions and have the authority to shut down and ensure that hazards are eliminated. Performs and documents the Daily Excavation Check and knows when inspections are due. It must be ensured that the location of underground structures or utilities is properly located. Adequate protective systems, working methods and personal protective equipment should be identified and ensured at the site. Any anthropogenic cut, cavity, trench or depression in the earth's surface created by the removal of land.
Visual inspection of the fully open pit is produced by a geological engineer... He also deals with the description of the soils that have been opened in the walls, and on the basis of this description he examines the quality of the soil on the walls of the pit. The geological engineer compares the information obtained with the data that are available in the technical report on engineering and geological surveys. After going through the whole list necessary work, the engineer draws up an act of survey of the pit. In it, he describes the uncovered soil, indicates the presence or absence of uncoveredgroundwater , analyzes the compliance of the actual pit elevations with those that appear in the project, and also indicates other additional information.
Refers to soil that tends to break along certain crack planes with little resistance, or material that exhibits open cracks, such as tensile cracks on an open surface. An atmosphere that is oxygen-deficient, potentially explosive, flammable, toxic, corrosive, oxidative, irritant, toxic, or otherwise harmful that could result in death or serious injury.
Methods for protecting excavation personnel from caves, falling material or rolling outside, or collapsing adjacent structures. Defense systems include the use of support systems, tilt and desktop systems, defense systems, and other systems that provide the necessary protection.
It is important to survey procedure was carried out with a drained base surface. Quite often, engineering surveys for this work are subject to some complications. So, for example, in urban conditions (with increased building density), technogenic complications arise: when digging a new foundation pit, fragments of old foundations and communications, as well as sections of technogenic soils, are encountered. In this case, additional soil sampling is carried out and its study is carried out for a more accurate study of the building site.
Registered professional engineer
A person registered as a professional engineer. A structure that is capable of withstanding the forces imposed on it by the cave and thus protecting the staff with the structure. Shields can be a permanent structure, or they can be designed to be portable and move as work progresses. Also known as trenches or trenches.
Construction such as metal hydraulic, mechanical or wooden system an anchorage that supports the sides of the excavation and is designed to prevent caves. A method of protecting employees from caves by dredging to form excavation sides that are sloped away from the excavation to prevent a cave. The angle of inclination depends on differences in factors such as soil type, environmental conditions and application of injection loads.
If there are significant discrepancies in the results of the control soil sample with the accepted final engineering and geological results in the project, then additional engineering and geological surveys are assigned to this site. The scope of these studies should be sufficient to make the necessary changes to the project. If you do not adhere to this recommendation, then the existing differences can lead to a change in the decisions made in the project or the opening of soils, in the engineering-geological report for which there is no data.
Most stable: clay, silt and clay. There is no type A soil if it is fractured, subject to vibration of any type, previously disturbed or water seeped. Least stable: gravel, loamy sand, soft clay, submerged soil, or dense, heavy unstable rock and soil from which any water seeps.
Mixed types. The soil needs to be classified based on the classification of the soils in the weakest soil layer. A narrow excavation was made below the surface of the earth. In general, the depth is greater than the width, but the width of the trench does not exceed 15 feet. If molds or other structures are installed or designed during excavation to reduce the size, measured from the molds or structure to the side of the excavation, to 15 feet or less, the excavation is also considered a trench.
The survey of the pit is completed upon receipt of the Act on the performance of work, which describes in detail the excavated soils in the investigated area, groundwater, if present (absent), compliance of the actual pit marks with the design marks and other information.
Components of the documentation for the survey of the pit
The final documentation should contain the following components:
The competent person must be identified by name on the digging permit for all excavations 4 feet deep or more in any part that personnel may enter. The location of sewer, telephone, fuel, electricity, water lines or any other underground structures that may be discovered during earthworks, must be identified and marked prior to excavation opening. The project manager should take the necessary action with the appropriate agency to protect, remove, shut down or relocate underground structures.
working drawing of the foundation, foundation pit and fixtures (if any were changed during the construction process);
acts of geodetic breakdown of the pit;
list for permanent benchmarks;
individual acts of execution hidden works (bearing capacity of soils, bedding device, properties of base soils);
an act of survey of the pit (which is drawn up by a geologist on site).
What it is
If the exact location of these installations cannot be determined, work may be undertaken with caution if detection equipment or other safe and acceptable means is used to locate the utility. Excavations must not endanger underground structures or workers employed in this work. Utilities left in place should be protected by barricades, bracing, suspension or other means necessary to protect employees.
Excavations should be isolated from public access by a significant physical barrier. Barricades, lighting and wiring must be properly installed prior to excavation work. All temporary excavations of this type must be completed as soon as possible.
This documentation is accompanied by project plans and as-built ones, as well as pit sections with reference to the foundation axes; indicators of control drilling, indicating both design and actual characteristics for soil conditions; test report bearing capacity soils (if carried out). In some cases, additional drawings of the pit fences are attached, if any.
What is included in the survey documentation
Fences, barriers or barricades should be installed around the excavation site next to paths, roads, walkways or other traffic areas. Using barricade tape alone is not considered a sufficient isolation method when excavating unattended. Warning lights or other lighting should be used as needed for public safety at night.
Wells, holes, pits and similar excavations must be effectively barricaded or covered and dispatched. Walkways or bridges used by the general public to cross an excavation site should be equipped with standard railings. All equipment, materials, materials, buildings, roads, trees, storage facilities, boulders, etc. Those that could pose a hazard to excavation personnel should be removed or supported as necessary to protect personnel.
In fact, a boiler room survey is an assessment of the work performed for their safety during operation. This estimate is made on initial stages, since after the start of subsequent work, the elimination of various defects that are revealed in the course of the survey will be impossible.
The competent person in charge of excavation is responsible for determining the type of soil. Visual test. Assess the conditions around the site, including the soil adjacent to the site and the excavated soil. Look for any signs of vibration. Check for holes for cracks along the failure zone, look at existing utilities that indicate the soil has previously been disturbed, and observe open side excavation to show signs of multi-level geological structuring.
An example of registration of an act of inspection of open ditches and pits
Look for signs of bulging, boiling, or peeling, as well as signs of water seeping from the sides or bottom of the dig. The site adjacent to the excavation should be assessed for foundations or other incursions into the failure area, and the assessor should check the distance from shore to the edge of the excavation.
Pit survey - this is a control procedure, participation, in some cases, can be taken by representatives of the relevant state bodies that oversee the construction industry, as well as independent experts, if necessary. All participants in such works are notified by their performer in advance. If, as a result of the acceptance of the work, any defects are performed, the developer or customer has the right to demand their elimination at a certain time.
Water seepage into excavation Vibration from road traffic or equipment Signs of bulging, boiling or flaking Cracks along the failure zone. Finger Penetration Test: Try to press your thumb firmly against the soil in question. It should be noted that the thumb penetration test is the least accurate test method. Drying Strength Test: Take a dry soil sample. If it crumbles freely or with moderate pressure into individual grains, it is considered grainy.
Components of the documentation for the survey of the pit
Dry soil that ends up in lumps that subsequently breaks apart into smaller clumps is likely clay combined with gravel, sand, or silt. Plasticity or wet thread test. Take a wet soil sample. You can also use a pocket penetrometer, shear force, or torvan to determine the unlimited compressive strength of soils. When excavating more than 4 feet deep, a method of protecting people entering from the cave must be used. Acceptable protective methods include tilting, bench, shielding and securing.
Before proceeding with the construction of a house, the developer must assess whether the soil will withstand the additional load. Practice shows that you should not rely entirely on the result of the geotechnical survey carried out the day before. You must personally make sure that the calculations are correct. If you do not pay due attention to the procedure for examining the bottom of the pit, you can face irreversible consequences in the future, up to the collapse of the building. The most at risk are facilities located in areas with significant traffic, for example, near the metro. In such conditions, even a small flooding of the building promises to turn into a disaster.
Snapping, tilting, snapping and shielding requirements
General: Excavations under a foundation or wall foundation require a support system designed by a registered professional engineer. Sidewalks, sidewalks, warehouses or other similar structures are not eroded unless a support system or other protection is provided to protect employees from potential collapse. The most often preferred methods of protection are tilt or bench; However, overlap or shielding is used when location or depth is made oblique to an acceptable angle impractical.
Survey of the foundation pit of a built house
It is possible to make a decision on the examination of the bottom of the pit and draw up an act based on its results, even if the house has long been commissioned. Such a need arises:
- due to changes in the construction of a new building or its foundation during the period after the completion of construction;
- with a sharp change in the hydrometeorological factors of the territory (for example, an increase in the level groundwater or the formation of landslides).
Often, the survey of the pit is carried out several years after the delivery of the house. And if the situation is not developing in the best way, urgent measures are taken to strengthen the foundation or drain water.
Slope: Maximum allowable excavation slopes less than 20 'in soil type and horizontal angle. Benches of 2 feet or less are preferred. The angle developed by the edge of the bench must not exceed the maximum slope allowed for this type of soil. Trenchers or trench shields are designed to protect workers from caves and similar incidents. The trench shield is lowered into the excavation and workers can then enter the protected area in the shield. Only trenches designed or certified by a registered professional engineer may be used.
Safe foundation
The survey of the soils of the foundation of the excavation ensures the accuracy of calculations during design, and, as a result, the safety of the building. The survey will help establish:
- whether the rocks indicated in the technical report and the actual cut layers are identical;
- where is the zero level of the pit, and whether this point corresponds to the parameters of the prepared project;
- whether the reference marks coincide in levels.
Use is limited to those trenches for which the shield is certified. The manufacturer must approve any modifications to the panels. The area dug between the trench box and the trench surface should be as small as possible. The space between the trench box and the side of the cut should be backfilled to prevent lateral movement of the box.
Trenchers can be used in combination with a tilt and bench. The box should extend at least 18 inches above the surrounding area if tilted toward the excavation. This can be achieved by securing an area adjacent to the box.
Pit survey procedure
The survey of the pit is carried out with the help of a geologist, and the result of the work is accepted by a special commission consisting of a representative of the customer, the contractor and state bodies involved in the control and supervision in the field of construction.
The survey of the pit by a geologist is carried out in several stages:
- introductory inspection;
- assessment of spatial characteristics and their possible dynamics;
- study of the physical parameters of soil samples (the specialist takes samples from the walls of the excavation undergoing inspection);
- comparison of the results obtained with the indicators recorded in the technical report;
- preparation of an act of survey of the foundation pit, which contains data on the characteristics of the soil, the occurrence of groundwater, the correspondence of the foundation laying points, etc.
The result of the survey becomes the basis for the commission's decision: to start construction at the design levels or an offset will be required.
Complications and risks for builders
Examination of the pit can be very unpleasant surprises. Often the procedure is complicated by a number of circumstances:
- The area is regularly flooded and it becomes necessary to drain it first.
- The site is experiencing increased stress in the form of old engineering networks or foundations. In this case, when examining the bottom of the pit, additional soil samples will have to be taken.
- There are significant discrepancies between the results of the survey of the excavation by a geologist and the design data. This situation requires new engineering and geological surveys, the composition and scope of which will be determined by the commission. Based on the results of additional research, the construction project is being adjusted.
Pit survey certificate
The final document of the survey is the certificate of survey of the pit, provided for by SNiP. It contains comprehensive information about the investigated soils and the characteristics of the pit itself. The act is carried out in several copies: for the customer, contractor, geological firm that carried out the survey, as well as state supervisory authorities.
