It will be about what the concept of “cramped construction conditions” means and what factors influence this process. Let's talk about the details of the work and the change in estimates. We will answer many other interesting questions in this article.
General view
An explanation of the constrained conditions in the construction should begin with a designation of a number of factors that influence the construction of buildings and structures within the city. These include:
- Traffic intensity of pedestrians and vehicles near construction work.
- Considering the nature of underground utilities: its branching.
- The presence of structures (residential complexes or manufacturing enterprises), as well as the preservation of landscaping of various kinds during construction.
- The presence or absence of the possibility of storing materials in the territory allotted for construction.
- Compliance with safety regulations at the construction site, taking into account the rules and regulations for the operation of assembly cranes.
Thus, from the above it follows that the definition of constrained conditions is reduced to various kinds of interference that affect the time and financial costs during the construction of a particular object. Difficulties can also be caused by temporary and auxiliary buildings, heavy construction equipment and everything that is an obstacle to the implementation of the necessary activities for the construction of an object.
Description of the building process (reconstruction)
In order to start construction, you need to get some documents:
- A comprehensive urban development decision on where the developed facility will be located (built).
- The decision of the architectural plan (concept). This includes the following stages: the place where the building will be located; its volumetric model; setting the boundaries of the territory; interaction with the environment.
Thus, the cramped conditions for the construction and reconstruction of buildings (residential) are classified as internal and external interference.
For the first option, the main base is the lack of space in the borders for the organization of the construction process, which is previously approved by the general construction plan. What causes this? There are several reasons:
- A small distance between existing facilities of the site, as well as operated buildings within a given border.
- If the existing utilities pass near the building.
External constrained conditions
They are characterized by the following features:
- A small distance from the ongoing construction to buildings that are in operation outside the site, but at the same time fall into the coverage area of the mechanisms.
- The width of the carriageway outside the construction site is insufficient to deliver the necessary mechanisms or materials to the construction site, but is still used for these needs.
- The influence of the sanitary and hygienic conditions of residential complexes that are located outside the boundaries of the installation work (for example, noise).
Therefore, there are problems that can be eliminated according to the project. These include:
- Communications that can be corrected (redone). This includes both underground and terrestrial species.
- Demolition of buildings that are in operation.
The crane, in cramped conditions, depending on its operation, must be limited to four movements in various combinations according to the safety protocol:
- boom rotation;
- moving the crane along the crane path;
- departure of a hook suspension;
- lifting and lowering the hook suspension.
It is recommended in the installation cabin to display the action plan for the zones on the display: working, warning and forbidden.
When one of the indicated combinations enters an undesirable zone, the system should give a warning sound signal, after which the actuators of the crane mechanisms must switch manually or automatically to reduced speeds.
In this regard, the crane must be prepared, that is, configure the whole system:
- install a sensor;
- mount or position a microprocessor device in a convenient place;
- carry out the necessary work in an electronic circuit to turn on the crane;
- set up a program, test and start the system.
Foundation
Building in cramped conditions is based on laying the foundation. In order to avoid low-quality structures, great attention is paid to this particular stage. It is necessary to calculate all the risks associated with the construction (for example, the movement of underground slabs, which may affect the subsidence of the base of the building in the future and lead to the rapid destruction of the building).
Therefore, if the objects are located at a small distance from each other, then an identical foundation should be used, the same as that of the previously constructed structures. This means that in terms of its composition and level of penetration, the foundation of the new building should be the same with already rebuilt buildings. Otherwise (different properties of the flooded base on which the object is located) it is necessary to study and analyze in detail the influence of the foundation of both buildings on each other.
What can happen in case of different types of foundations? In cramped conditions, for example, between a pile and tile base, the adjoining zone under the grillage of the old building can cause loosening of the soil, which will weaken the bearing capacity of the piles, which will lead to partial destruction of the old structure.
For tight interaction between two objects (new and old), provided that identical bases are used, pits should not be developed up to the wall of the existing foundation without protective measures. Otherwise, this can lead to the elevation of the soil from under the sole of the existing foundation into the pit. To avoid such embarrassment, which will be very expensive, you must:
- Dig a pit along the length of the existing foundation with small grips, about 3-4 meters to the corner of the building.
- The foundation should be laid along the chain: first in the first dug mini-foundation pit, and then in subsequent holes.
In the case of different bedding depths, it is absolutely worthwhile to use a dowel sheet at the junction, due to which stability is checked after a foundation pit has been dug for a new foundation.
Sheet piles and their purpose
A tongue-and-groove wall (or nearby) is called a continuous waterproof structure, which plays the role of a barrier against water entering the pit or its washing out. Based on the definition, if cramped conditions in construction are carried out on soft soils between high-rise buildings, then a dowel sheet is installed according to the safety protocol.
There are several types of such fences:
- bored reinforced concrete;
- driven reinforced concrete;
- Larsen sheet pile (metal).
In the construction process, laying in cramped conditions is most often carried out using bored monolithic tongues. The dependence of its diameter and the deepening of the pit (the number of levels located underground) varies between 32-100 cm and more. For example, if the depth is over 4.5 m, then a sheet pile of piles and the installation of soil anchors are installed, the diameter in this case should be 32 cm.
Warehouse and its role
Properly organized work in cramped conditions involves high speed construction or reconstruction of the object. To do this, you need to allocate a place where stocks of various materials necessary for construction will be stored. They are delivered to the site in specialized containers and packaging. All structures enter the action area and are mounted using transport mechanisms. It is strictly forbidden: storage on the site of long products and the shipment of materials in bulk.
Large assembly of structures is allowed (exceptional cases), if there is:
- technical justification and development of the project of specialized equipment, which together provide the situation during installation of enlarged structures;
- relevant documentation for the construction project regarding the foundation or method of fastening the deepened pits;
- reporting surveys on engineering-geological or technical research of the building;
- programs for monitoring underground spaces and structures that are subject to geotechnical expertise.
Limited manufacturing process
Cramped working conditions are the implementation of installation work, which is associated with many factors that negatively affect and impede the production process. Thereby:
- increased time for technological operations;
- rarely, but overspending of building materials is noticed;
- the time process of finding equipment at the production site slows down;
- in the end, the actual costs of the organization (contractor) for the full range of construction works increase.
For the term “cramped conditions”, the concept of MDS (methodological documents in construction) is quite well-known among specialists. There are a number of regulations that are necessary in the construction of facilities. One of the common documents is MDS 35 on cramped conditions. What does he mean? Let's consider in more detail.
The document reflects the methodology that establishes the price tag of construction products throughout the Russian Federation. There is a bunch of estimated standards that determine the cost of the whole complex of works. They are built in a certain sequence:
- type of work or cost;
- social object;
- launch complex;
- construction phase;
- complete complex for the construction of the building.
In MDS about constrained conditions, the calculation is described:
- direct costs;
- overhead costs;
- estimated costs.
For the first group (direct), the cost of resources that are needed to perform various types of work is taken into account: material, technical and labor (budgeting). The second group is responsible for the costs of organization (construction, installation), that is, it is involved in the creation of general production conditions for maintenance, organization and management. The estimated amount includes: funds that are needed to close certain expenses in a generalized form, for production development, the social sphere and material incentives. MDS on constrained construction conditions recommends a list of the following conditions:
- construction of facilities for the needs of workers who are dismantled at the end of the construction process;
- rental of temporary premises, which will subsequently be liquidated;
- moving structures for various purposes (for example, storage facilities);
- expenses and rent for the maintenance of inventory buildings such as a designer (collapsible);
- the presence of closed (heated) or open (unheated) warehouses for storing materials that are brought for construction work to the site;
- construction of multi-purpose workshops (production);
- installation of temporary power plants for special occasions and needs;
- installation for cleaning surface water supplies.
Communications
The laying of communications is an important moment in construction, which extends to the gas pipeline and water supply system. Using one of these conditions as an example, let us consider the whole process in detail.
Cramped conditions of the gas pipeline mean that before direct installation there should be a ready and thought-out plan of action, in which all risks are thoroughly studied and taken into account. Installation takes place in two ways: ground and underground.
Important. The wires that are underground must be in the embankment. The parameters of the gas pipeline under the ground are calculated based on thermal and other technical characteristics. When laying communication for gas on specific sections of the road, namely between buildings and under their arches, it is necessary to use gas pipelines with a pressure of 0.6 MPa in accordance with the approved standards (at a distance of 5 m), and when combined with single buildings (auxiliary) it is allowed:
- reduce by 1/2 the distance between objects in cramped conditions;
- no more than 1/4 in special conditions.
Gas pipelines above the specified pressure are laid in the following cases:
- when introduced into the industrial zone;
- in the undeveloped part of the village.
In both the first and second cases, the installation must satisfy the layout of construction projects relative to the village plan in which the installation is carried out. As for overhead laying, it is not always used, but only in certain cases:
- along the perimeter of the inner walls of buildings of housing complexes;
- on specific sections of the road;
- on the border of obstacles;
- at the intersection of technical support networks.
It is carried out only if there is a justification and access of unauthorized persons to the gas system is limited. In soil or hydrological conditions, a gas pipeline with a system of barrage facilities can be laid.
Estimates and its calculation
Cramped conditions in the estimate include taking into account increasing coefficients to standard labor costs.
Payment in this case depends on the type of work performed and can be taken into account in each position or according to the final estimate. Also, the estimate can be displayed in two forms at the same time: separately for each position and total.
Grounds for calculating the estimate:
- The task setting for the project, which is issued by the customer.
- The decisions provided in the design documentation adopted by the head of the company.
The customer’s tariff is determined on the basis of the analysis of the estimate documentation, which contains information on the performance of contract work. With the help of this information they can:
- pricing policy proposed by the contractor;
- constants are formed: the cost at the end of the held bidding with the execution of the protocol of all agreements for the construction of the facility in the required form.
Given the MDS on cramped conditions, the cost of a building or construction is determined as part of preliminary studies with the allocation of prices for each separately taken queue, industrial facility and residential civil construction. Also, in individual cases, individually can be determined:
- construction cost;
- expansion of construction;
- renewal;
- technical modernization of the construction industry base and other facilities in this area.
It is desirable to draw up construction cost calculations with justification of investments for a specific type of construction for each type of work. This will greatly facilitate the financial part of the issue.
How is a numerical indicator determined?
The concept of the correction factor and the definition of constrained conditions are very closely intertwined. So, the coefficient in the installation of construction works increases depending on a number of factors. When constructing a building in difficult production conditions, the norms of this indicator are established with respect to time costs and prices for the corresponding work:
- For existing enterprises in the presence of technological equipment from 1.1 to 1.2; at metallurgical, chemical or oil enterprises from 1.1 to 1.25.
- In cramped conditions at construction enterprises from 1.1 to 1.15.
- In warm rooms 1.1.
- In the security zone of the air systems of power equipment and items under voltage from 1.1 to 1.2.
Finally
So, we found out that the constraint of conditions means limiting the possibility of using mechanization equipment, materials, products, structures, as well as the impossibility of rational organization of the site due to the presence of a complex of obstacles.
The cramped conditions of the existing urban development suggest the presence of spatial obstacles on the construction site and the adjacent territory, restrictions on the width, length, height and depth of the working area and underground space, the location of construction vehicles and vehicles, an increased degree of construction, environmental, material risk and, accordingly, enhanced security measures for workers in the construction industry and the living population.
Estimated documentation may be developed on its own by the design organization, if this is provided for by the contract. Specialists who develop budget documents establish the size of the correction factor, guided by the characteristics of cramped conditions, which must necessarily be displayed in an act of a certain form.