The harsh natural environment of Kunlun Mountain.
1, project overview
The geological, geomorphological and geological conditions of Xidatan fault basin, rock canyon gully, Kunlun mountain pass, Kunlun mountain pass basin and unfrozen spring valley have undergone unique, complex and large-scale projects.
Xidatan fault basin is flat and open with undeveloped vegetation. During this period, small gullies developed, and the deep Quaternary was mostly red and round gravel alluvial soil and gravel soil. On the surface islands, in permafrost regions, the frozen soil is 2.8-3.5m and the thickness is 5m-20m. The ground temperature of frozen soil is higher than -0.5℃ on average, so ice and frozen soil should be used less.
These hilly areas of Kunlun Mountain have complex geological structure, sparse topography and vegetation, with an altitude of 4,500-4,800 meters, including ancient glacier relics, modern glaciers, cold weathered landforms, rocky glaciers, frozen soil development, frozen soil frost heaving, ice cones, melting mudslides, collapses and landslides, with a thickness of 60 m-. The annual average ground temperature is -0.5℃-2.6℃, and the permafrost is stable. The proportion of mountains is large, the tundra is cold, about 48%, and the engineering geological conditions of frozen soil with uneven distribution and high ice content are poor.
Bid section of large-scale main works: subgrade earthwork exceeds 5310.4 million cubic meters (frozen soil in this section is 504,300 cubic meters); Ballast132600 m3; 32 extension lines of various bridges10764m, of which bridge and bridge 18 exceed 10000 linear meter; Tunnel1686m; Culvert 83 is nearly 2000 square meters.
Bidding is centralized, and time is tight for big projects. Construction started on July, 2006 1 day, and all the main works reached the laying conditions on February 20th, 2002.
2 principles of construction organization
According to the actual situation of bidding construction, the following construction principles are determined: "grab the tunnel, grab the subgrade and protect the bridge" and "more machinery and less manpower". "
According to the bidding requirements of the total construction period, the construction period is controlled by Kunlun Mountain Tunnel. Arranged in the Kunlun Mountain Tunnel, highlighting the word "grab". At the same time, make good use of favorable seasons to cut subgrade and fill and dig, and promote bridges and culverts.
For the characteristics of plateau, especially the threat of hypoxia to human survival, people should be thinner, use more machinery and less manpower. Mechanical energy can be resolutely done without manual work; What the mainland can do cannot be stopped; What can be done under the mountain is determined not to look at the mountain.
3 Construction organization
3. 1
The formation of a lean and efficient command structure. Deputy Chief Commander of Qinghai-Tibet Railway Engineering Command of China Railway Fifth Bureau (Group), subsidiaries and functional departments of Chief Engineer's Project Department, including professionals who are fully equipped, skilled, dare to fight hard and are not afraid of difficulties.
3.2 Construction objectives
3.2. 1 time limit for a project target
① Commencement date of Wang Kun Frozen Soil Station on the northern border: July, 200 1 year. Completion date of the main project: June 30, 2002.
② The commencement date of the tunnel entrance of Wang Kun Railway Station: July 2006 1 day, and the completion date of the main project of the line: 20021October 30.
③ commencement date of tunnel: July, 2006 1 day, June, 2002165438+1October, 3 1 day, when the main works were completed, the laying conditions were met.
④ The date from the exit of the tunnel to the start of thawing spring: March 1, and the completion date of the main line project in 2002: 20021October 30.
⑤ Completion time of each bid section: July 2003 1.
Quality objective
Ensure that all projects meet the current acceptance standards and the relevant regulations of the Ministry of Education on railway engineering construction quality. The qualified rate of the project is 100%, the excellent rate of the station project is over 50%, the excellent rate of the fourth electrical project is over 95%, and the excellent rate of the project is over 90%. All bids have reached a record quality level, which meets the requirements of all-round planning, creating excellence and striving for national quality projects.
Security goal
1) put an end to heavy casualties; 2) The control rate is less than 2 ‰; 3) Put an end to illegal command, illegal operation and inertia accidents.
3.3 Resource allocation
1。
The Qinghai-Tibet Railway, especially for human resources in the natural environment, can consider factors such as rotation and rest, and allocate the required labor force according to 1.3 times the labor force and employment planning coefficient. Full-time technical management, scientific and technological research, medical care and other personnel.
2。 Mechanical configuration
Disadvantages: due to the high mountain environment, the power of internal combustion engine is seriously reduced, so it is necessary to use motors. However, only the internal combustion type can be used for earthwork excavation, loading and unloading, transportation and crushing machinery, and it has sufficient mechanical reserve capacity. Because there is no power grid bidding, various forms of self-generation are adopted, and the layout of one of the key equipment and generator equipment must be carefully studied and solved.
3。 Life logistics
The developed Nutrition Guide for Plateau Construction Workers is located in the living procurement station and food processing canteen in Golmud, which tries to process all kinds of food raw materials into finished or semi-finished products and reduce the cooking operation procedures on the construction site. A nutritious meal in strict accordance with human needs. Every day, a special refrigerated truck delivers all kinds of food to the station.
4。 Medical treatment and sanitation and epidemic prevention
The medical rehabilitation center in Golmud is responsible for the treatment and recuperation of the wounded and sick. The imported Kunlun Mountain Tunnel Project Department has set up four medical first-aid centers, which are responsible for the on-site first-aid of operators. And set up epidemic prevention stations to participate in epidemic prevention and nursing work.
Main measures and objectives of health and epidemic prevention work:
Participate in the comprehensive physical examination and regular physical examination methods before the workers enter the site; On-site environmental testing, health education and early health care. In addition to importing scattered camps set up by emergency medical centers and health stations in Kunlun Mountain Tunnel. Give priority to basic prevention and self-care, supplemented by drug treatment, and enhance the health awareness of diseases. Follow up and observe the health records of each worker, medical staff and leaders, master everyone's physical condition, shorten working hours, generate electricity as much as possible as needed, and reduce labor intensity and physical protection. In accordance with the provisions of labor protection, scientifically prepare nutritious meals, pay attention to cold and warmth, prevent diseases, supplement oxygen when necessary, take oxygen medicine, prepare enough first-aid supplies, and master first-aid techniques. In order to maintain normal production and construction, the team implemented some rotations and short breaks to ensure that the disease would not be frostbitten and died. Acute mountain sickness makes every effort, at 3% or below.
3.4 Construction scheme
3.4. 1 Kunlun Mountain Tunnel
According to the special environment of Kunlun mountain tunnel, such as alpine frozen soil, the following principles are determined: first, "more drilling and less cost, weak blasting", second, "short footage, strong support and tight lining" and third, "more machinery and less manpower"
There are four construction organizations on the five sides of the entrance of Kunlun Mountain Tunnel, namely, the entrance working face, the # horizontal hole working face, the exit working face and the # 2 horizontal hole working face (two working faces). The specific plan for the length of the construction surface is as follows:
Import side: The planned construction of import mileage DK976 +250 and DK976 +940 is planned to be 690 meters.
1 # transverse tunnel surface: 1 # the crossing mileage between transverse tunnel and main tunnel is DK876 +940, and it is planned to build DK976 +940- DK977 +200 with a construction length of 260m.
2 # cross-hole surface: the crossing mileage between 2 # cross-hole and main hole is DK977 +500, and it is planned to be built from DK977+200DK97786, with a construction length of 586 meters and divided into two surfaces.
The export faces the planned construction of export mileage DK977 +936 and DK977 786, and the planned construction 150m. If the human face speed is faster than the construction progress, the construction can continue to move forward until it passes-.
Concrete construction method:
Before the formation of rail transit, manual drilling, smooth blasting, sectional bench excavation and special machinery will be used for wheel ballasting and transportation. After the formation of rail transit, claw machine, battery car and shuttle bus are made by drilling with three-arm tie rod, smooth blasting, full-face excavation and ballasting. Lining concrete pumping, hydraulic lining trolley construction. For a large number of soft and broken geology or shallow bench construction, it shall be carried out according to the principle of advanced support and short footage.
Construction of waterproof and drainage structure and insulation layer: waterproof and drainage structure and insulation layer are special, and the key structure of Kunlun Mountain Tunnel is an indispensable part, and its construction technology and quality can easily ensure the quality of Kunlun Mountain Tunnel.
At present, there is no mature experience in waterproof and insulation construction of tunnels in permafrost regions at home and abroad, so it is necessary to select suitable waterproof and insulation materials, conduct a lot of research and performance comparison tests, and complete on-site waterproof and insulation process tests, so as to formulate tunnel waterproof and insulation construction methods and technologies, and provide reliable technical support and scientific construction technology for the construction of waterproof and drainage quality inspection methods, joints of thermal insulation and waterproof boards and joint treatment of Kunlun Mountain Tunnel, so as to ensure the construction quality of waterproof and insulation layers.
bridgework
According to the engineering characteristics, especially the special requirements of buildings, bridges and culverts in permafrost regions, advanced construction methods should be adopted, combined with various new monitoring means used in the test. In the process of construction, frozen soil environment, good ecological environment protection, water and soil protection, after the completion of construction, we should pay full attention to the recovery surface.
1。 Pile foundation construction
According to the geological characteristics of the Qinghai-Tibet line, it is basically unnecessary to make a wall. The main hole-forming machine of rotary drilling rig can prepare some impact drills, and try to use dry hole-forming method to deal with stones and hard rocks encountered in drilling.
The freezing force is designed for piles, and the ground temperature monitored by pile foundation soil piles is completely recovered before the freezing construction of pile foundation soil. Or use artificial cooling method to accelerate refreezing to meet the schedule requirements. P> Within the seasonal thawing layer, piles and caps need some special treatments to reduce the contact and mechanical action of freezing and thawing.
2。 Bridge pier construction
Another external thermal insulation and moisture retention system for low-temperature early-strength durable concrete piers must be set to ensure the normal development of pier concrete strength in cold and dry environment.
culvert
Most of the contract sections are rectangular culverts. Culverts should be prefabricated centrally and assembled by truck crane to achieve the purpose of intensive production and quality assurance.
concrete work
1。 Main technical requirements and difficulties
Natural conditions such as oxygen, low temperature, low air pressure, strong wind and strong radiation are harsh, so special concrete must be used to meet the structural design requirements. Main technical requirements and technical difficulties
(1) Ensure that the concrete strength grade should meet the design requirements when the surrounding medium is negative temperature (different construction time and negative temperature) after concrete pouring.
② Ensure the durability and corrosion resistance of concrete meet the design requirements.
(3) It is necessary to ensure that the concrete is poured within the specified time, and the key anti-freezing strength (≥4 MPa) and formwork removal strength meet the progress requirements.
④ Concrete mixture is required to have good low temperature resistance, fluidity and plasticity, stability, confidentiality and pumpability.
2。 Construction technology and quality control
Due to the large amount of construction, special quality control is needed. From the choice of raw materials and additives, complexity, concrete mix design, concrete mixing, transportation, pouring, vibrating, maintenance, inspection and quality control, a series of effective technical measures, training of on-site construction technicians and guidance of development and construction work are needed to ensure the bidding of concrete construction quality.
In the special natural environment of Kunlun Mountain, admixture is the key factor to ensure the special performance of specific design requirements. Through research, the selection of bidding additives is as follows:
① Low early strength and durability concrete antifreeze is selected for bridge pile foundation north of Kunlun Mountain Pass, and low early strength and durability concrete antifreeze is selected for wharf, combining with early strength.
② The long-lasting, corrosion-resistant early strength, frost-resistant and corrosion-resistant low early strength concrete admixture is selected for the bridge pile foundation south of Kunlun Mountain Pass.
roadbed
1。 Project overview
The subgrade in the bidding area is filled with 3.82 million cubic meters and excavated 1.02 million cubic meters. There are 474,000 cubic meters of earth and stone, 57,000 cubic meters of soil and water filling, 248,000 cubic meters of subgrade reinforcement and soil protection, 29,600 square meters of geomembrane laying, 547,000 square meters of geogrids, PVC pipes (φ 30)163,000 square meters, and polyurethane board128,000 square meters.
2。 Construction method
The parallel assembly production line of subgrade construction section is mainly mechanized construction, and there are many dead ends in mechanized construction. The method of combining manual small mechanical construction is adopted.
The promotion of water diversion, water diversion line and water diversion pipeline construction projects in line construction. Blockade and subgrade earthwork protection project, adopt continuous operation and rapid construction, arrange earthwork construction in time according to the progress of drainage project, and build road crest cutting dam first.
There are a lot of foundation treatment and ventilation rubble to create conditions for subgrade first. When cutting construction is carried out in frozen soil with high ice content, it should be carried out in cold season and warm season due to objective factors, and rapid construction should be organized. The cutting slope and bottom thawing frozen soil should be insulated and sheltered to ensure financial collapse and landslide before the construction is completed, so as to avoid hot and hot-melt debris flow diseases.
Only canned food, it is spring all year round.