Laying a road tunnel across N. Ershov Street

Contents

Technology of erection of buildings and structures

1 The situation in the construction area

1.1Specific description and purpose of the object

1.2 Design Input

1.3 Climatic conditions

1.4 Relief

1.5 Transport network

1.6 Pedestrian flows

1.7 Geotechnical and hydrogeological conditions

1.8 Geomechanical situation

1.9 Utilities

1.10 Plot Plan

2. Characteristics of the object under construction

2.1 Main Operational and Process Solutions

2.2 Service life and operation mode

3. Scope and Layout Diagrams and Solutions

4. Basic Design Solutions

5. Aicorrosion pipeline protection

6. Selection of organizational and technological scheme of construction

Forcing Method

7. Preparatory period of construction

8. Construction of open and underground workings

8.1 Breakdown of earthworks

8.2 Drainage and lowering of groundwater level

8.3 Temporary attachment of recess walls

9. Assembly and connection of pipes on welding

10. Testing of pipelines

11. Observation, assessment and forecast of the state of the mountain massif

breeds

12. Final Construction Period

13. Labor protection during the construction of the facility

List of literature used

1.1Specific description and purpose of the object

Since Ershova Nikolay Street is one of the most important and throughput artery connecting the city center and the environs of Kazan. And also due to the fact that the capacity of the old collector began to not meet the needs of the constantly growing and building Soviet district of Kazan. It was decided to lay a new collector tunnel. In the general case, the laying of urban utility networks is usually built in an open way. In our case, in a built-up area, as well as in order not to block traffic on Ershov Nikolai Street, underground construction methods must be used. After the technique of economic analysis and engineering survey robots on the ground, it was decided to penetrate the sewer collector tunnel by pressing methods.

sewage collector consists of metal rings with diameter of 500 mm interconnected by welding and waterproofed from underground waters by adhesive waterproofing.

1.2 Design Input

As a design task, I received the laying of a metal case with a diameter of 500 mm across Ershov Nikolai Street by pressing. This underground structure is intended for pipes of a collector tunnel under road and tram tracks.

Site Plot Plan, sketched (on site).

1.3 Climatic conditions

According to SNiP 2.01.82. "Construction climatology and geophysics" Kazan is assigned to the climatic region II. Standard depth of rock freezing is 1.6 m.

1.4 Relief

The site for the construction of an underground sewage collector is located at the intersection of Ershov and Zinin streets, in the vicinity of Ershov, 26. At the site of digging a special chamber there is a small squalor with planted trees, shrubs and other plantations.

1.6 Pedestrian flows

The volume of pedestrian flows is established by timing at the time of an intensive crossing. In our case, the maximum number of pedestrians passed is 108 people per hour.

1.7 Geotechnical and hydrogeological conditions

For the reasonable design and construction of the sewage collector, initial data are required that characterize the conditions of the environment in which the object should be erected. This refers to the geographical location and topographic conditions of the area, transport links of the construction area, the nature of urban planning and development, the location of terrestrial and underground artificial structures and communications, geological features of the soil mass, geotechnical characteristics of soils, the location and regime of groundwater and gases, climatic factors, etc. The identification of these conditions is the task of engineering surveys - one of the components in the general survey complex - design - construction.

Following geotechnical surveys, the following results were obtained:

EGE-1: Power 3.2m. The soup is plastic, saturated with water, not subsidence.

EGE-2: Power 3.8m. The sand is dusty, medium density, saturated with water, not leaking.

EGE-3: Power 4m. The clay is semi-solid, saturated with water, not sedimentary.

EGE-4: Power 4m. The sand is dusty, dense, moist, not subsident.

EGE-5: Power 5m. Clay is semi-solid, saturated with water, not sedimentary.

Soil characteristics are given in Figure.

The groundwater level is at an altitude of 123.50 m.

1.8 Geomechanical situation

The physical, strength, deformation and rheological properties of soils largely determine the technology of underground construction.

There are no weakened and weathered soils on the territory of construction of the sewage collector. Basically, semi-solid clays and dusty sands are included in the mining zone of the collector.

Groundwater level 123.50 m above the level of the Baltic Sea.

Considering the seasonal freezing of soil rocks and the necessary slope of gravity sewage, the depth of the reservoir, we take 3.0 m.

In the immediate vicinity of the object under construction there are one, two and three storey buildings at ul. Ershova house 14, 20, 26, 26a, 28. The buildings contain shops, offices, etc.

1.9 Utilities

The city communal networks include: storm and domestic sewage networks, water supply, heat supply; gas pipelines; power, low-current, telephone cables. All networks with the exception of sewage, usually only slightly exceeding the freezing depth or even less than it (in unpowered soils).

A cross section of the underground part of Ershova Street is shown in the figure.

1.10 Plot Plan

The construction plan is part of the integrated construction documentation and its decisions should be linked to the rest of the project, including the accepted work technology and construction deadlines set by the schedules. The construction plan solution must meet the requirements of construction standards, they must ensure the rational passage of cargo flows at the site by reducing the number of transshipments and reducing the transportation distance. These requirements, first of all, apply to mass and especially heavy goods.

The construction plan should ensure the most complete satisfaction of the domestic needs of construction workers, the decisions made should meet the requirements of safety, fire safety and environmental protection. Temporary construction costs should be minimal. Their reduction is achieved by using permanent facilities, reducing the volume of temporary buildings.

The object construction plan is designed separately for all types of buildings and structures under construction included in the civil construction plan. For complex objects, the construction plan can be drawn up for various stages and types of work.

During the development of the object construction plan, the sheet is primarily coated with existing buildings and structures, reconstructed and designed structures, existing and designed transport routes, utility network connection points. Taking into account the requirements of the work and safety technology, construction machines and lifting mechanisms are located, their movement and movement paths are indicated, the operation zones of cranes and lifts, dangerous road zones and areas dangerous for the location of people are determined.

The calculation determines the areas of open and closed warehouses and their location. Open warehouses are located in the area of the installation cranes. At least two-week stock of steel and five-day stock of reinforced concrete structures can be stored in acquired warehouses.

The demand for domestic premises is determined for a calendar period corresponding to the time of maximum simultaneous presence of workers on the construction site.

Utility lines shall normally be designed in a ring diagram. Sanitary and technical power supply networks are applied on the drawing with indication of diameter, length of pipes or section of electrical wires.

Electrical networks are recommended to be designed by air, on supports or searchlight masts. In areas of intersection of roads or operation of lifting mechanisms they are designed in the form of underground cables.

Transformer substation is designed by calculation and is located in the group of temporary buildings.

Power supply of lighting networks and power equipment is carried out using separate wires and cables.

Water supply networks are laid below the freezing depth or insulated. The distance from the water pipeline to the walls of the building is not less than 5 m, and not more than 55 m. To connect fire trucks, as a rule, fire hydrants at a distance of not more than 100 m are installed on permanent networks. from each other and not further than 2.5 m from the road. Fire hydrants are installed so that it is possible to close the ignition point with two jets. To meet the needs of the workers, a temporary sewage system is designed, the need for searchlight is calculated.

All calculations for the object construction plan are made on the basis of the work schedule, according to which the maximum need for the work plan is determined, according to which the maximum need for some type of resources, storage areas, lighting of inventory buildings is determined.

2. Characteristics of the object under construction

2.1 Main Operational and Process Solutions

The total length of the underground section of the pipe is 33 m, the depth of the coarse is 2.5 m from the level of the day surface. The sewer capacity of 500 mm diameter is 30 m3 per hour.

2.2 Service life and operation mode

The service life of the underground sewage collector (metal) based on the material used is 10-15 years. The operating mode is round the clock.

3. Scope and Layout Diagrams and Solutions

The sewage pipe is located at a depth of 2.5 m from m from the level of the day surface. The gravity of the sewage pipe is provided by the slope of the pipe, which is 3 °. The diagram is shown in Figure No.

4. Basic Design Solutions

Gravity pipelines and headers of fecal, storm and industrial sewage systems are laid with a slope, which is checked for each laid pipe separately. For this purpose in places of device of inspection wells there installed are flaps on which permanent sights and steel string are fixed along axis of pipeline. Pipe blanks are connected in accordance with welding joint and work procedure.

The length of the pipe passage by pressing 40 m. The material from which the pipes are made is metal. Pipes are coated with anticorrosion coating before pressing.

5. Pipeline corrosion protection

Underground steel structures, including pipelines and cables, are physically and chemically exposed to the environment. At the same time, electrochemical corrosion phenomena of metal of pipes, cable shells, etc. arise. In this regard, special protection of underground metal structures from corrosion is carried out.

Active protection means are special electrical devices used for the organized removal of wandering currents from the anode zones or for bringing pipelines into a cathodic state with current from an external source. To this end, insulating inserts and electrofilters are installed on the networks, and electric drains are installed in the anode zones.

Electric drainage is designed to divert wandering currents from the anode zones of the structure to the current source using an insulated metal conductor with a drainage device. There are direct (simple) and polarized drainage. In the first case, the drainage device has two-sided conductivity, in the second - one-sided conductivity.

Electric cable is connected to protected structure, for example, pipeline. The second end of the cable is connected to the running rail of the track or to the negative bus of the traction substation. The cable includes a drain device that passes a current of only one sign.

When the sign of the drained current, that is, the potential difference, changes, the drain device automatically turns off the system.

A drainage protection device on one of the underground metal structures leads to the formation of anode zones on adjacent underground objects, as a result of which they are destroyed. Therefore, electrical drainage is especially effective with joint (complex) corrosion protection of all underground metal structures with common protective devices.

6. Selection of organizational and technological scheme of construction

Depending on the purpose of the pipelines and the construction conditions, different piping schemes are used.

When laying external networks, the choice of the organization scheme of construction processes depends on the scope and conditions of work, the purpose and structural complexity of pipelines.

Due to the variety of conditions under which pipelines are laid, there cannot be a single process of work along the route.

The design documentation is drawn up in the form of process normals for complex processes for each typical gripping (installation area) on the basis of Job Instructions (for individual work processes) and start-up diagrams, in which the order of commissioning of the final sections of the network and the required capacity of specialized flows for completion of work are determined within the established time frame.

The order of movement of the links is indicated by the received flow patterns, where the boundaries of the sections (grips) are indicated. The timing of the processes and their timing, the need for technological and organizational breaks indicate cyclograms.

Forcing Method

Underground (closed) pipe laying without soil opening by means of forcing is used when they cross roads, streets, squares and tram tracks in cities and towns. In these cases, it is necessary to know exactly the location of all underground communications along the pipeline route, especially at the junction point, and take measures to preserve them.

The essence of the pressing method consists in the fact that the pipe is pressed into the soil massif with an open end, and the soil falling inside as it progresses is developed and removed by means of hydromechanization or manually.

The scheme of the process consists in the fact that on both sides of the road under which the pipeline is laid, two pits are dug: a worker with a length of 8... 13 m to accommodate the equipment and the laid pipe and a receiver with a size of 1.5 x 2.5 m on the other side of the transition. The depth of the pits is accepted at 40... 50 cm more than the design layout of the pipeline.

Working pit is equipped with stop for perception of pressure reactions from jack unit, one - two hydraulic jacks, guide frame and pit for assembly, welding, testing and insulation of mounting joint during pipe build-up. Oil pump is installed on pit berm to actuate hydraulic jacks.

By this method, pipes with a diameter of 500 to 1400 mm and a distance of up to 80 m are laid. This requires the installation of four and sometimes six hydraulic jacks, complicating the structures of the stop, frame for jacks and head.

It is possible to reduce the pressing forces by giving the cutting edge of the pipe a sharpened shape of the knife (at an angle of 15... 20 degrees with its thickening by 50... 60 mm in relation to the outer diameter of the pipe). Such knives in the form of steel sections up to 2 m long are used for laying reinforced concrete pipes.

The length of penetration from one working pit is from 30 to 80 m. Longer routes are divided into several sections. From each pit, penetration is carried out first in the direction of one section, then in the opposite one. Working and receiving pits are prepared for pipe pressing in the same way as for puncture.

Pressure from jacks to the pipe is transmitted by external shompoles. They, like the internal ones, are blocked on one side with the rods of the jacks or the pressure beam, and on the other - with the head .

Penetration speed and labor intensity depend on pipe diameter, gasket length, soil properties and methods of its development. With manual soil development, the process speed is 1.8... 3.2 m/shift, labor costs per 1 m of penetration - 7.8... 21 chel.h, with mechanized accordingly 1.8... 4 m/shift, labor costs - 6.4... 17.9 chel.-h.

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