H420 pneumatic pipe hammer is laid in Wuhan ¢ 820 steel pipe T Lin Jiahui Li Shuiming Hubei Province Shenlong Foundation Engineering Company 65.8 caliber large, long distance. In this paper, we summarize the selection and completion methods of the 1 program, aiming to provide a reference for the selection of the same management method under the condition of trapping the pipe. The first author introduces Lin Jiaxuan, male. In 984, he graduated from the Department of Geophysics of Changchun Geology. He is currently the chief engineer of the Ministry of Industry in Hubei Province. He is mainly engaged in the construction of non-excavation pipelines for uranium and pipelines. Tongyu Address Wuhan Economic Development 2 is the northern province of Shenlongji, the industrial company. Zip code. , 0056.
1 Introduction Since the introduction of directional drilling into non-excavation pipe laying technology in 19 years, our company has successfully completed the remaining projects of gas water supply and power telecommunications and thermal pipelines, and achieved good social and economic benefits.
In order to adapt to the expanding market demand for non-excavation engineering, expand the construction methods, and after repeated argumentation and comparison, the introduction of the Day 420 pneumatic hammer. This type of pipe hammer has wide adaptability to the stratum. It is almost suitable for all strata except rock formation. For example, gravel layer flow sand layer or even other technically difficult construction waste backfill layer can adapt to a wide range of pipe diameters to accommodate 325, 1200, 1 range. The laying of various pipe diameters has no effect on the ground. Because the cutting core is inserted into the pipe, even if the pipe laying depth is very shallow, the ground uplift and settlement phenomenon will not occur. The pipelaying accuracy is better than the waiting point, and the directional drilling pipe laying rig has an advantage. Complementary, expand the application range of non-excavation pipe laying technology.
In order to complete the laying of 820 electric steel bushings in Xiehe Hospital International Shopping Mall, only 420 pneumatic pneumatic pipe hammers were used for traversing laying, which avoids the laying of large-diameter pipelines in the silt layer in this area, which may cause the pavement and other structures to collapse. And the danger of destruction.
2Pneumatic pipe hammer pipe laying principle and process flow 2.1 Pipe laying principle Pneumatic pipe hammer pipe laying technology as an important branch of non-excavation pipe laying technology, its development has been nearly 35 years of history, a large number of foreign countries every year The pipe laying is done by this method, and the application is relatively mature.
The fistula hammer is essentially a low-frequency, high-impacting pneumatic impactor. It is powered by compressed air. The steel pipe to be laid is directly plunged into the stratum along the design route, thus realizing the non-excavation and pipe-laying tools. During the pipe laying process, the pipe hammer produces a large impact force. This impact force acts on the rear end of the steel pipe by adjusting the cone pipe excavator and the pipe head, and then passes through the steel pipe to the cutting head at the front end to cut the soil. And the frictional force of the stratum and the pipe body keeps the steel pipe continuously entering the soil layer. As the steel pipe advances, the cut core enters the steel pipe. After the steel pipe reaches the target, the cutting head is removed, the core in the pipe is discharged, and the steel pipe is left in the pipe, that is, the pipe is completed.
Only 420 type pipe hammer is developed by the Institute of Exploration Technology of the Chinese Academy of Geological Sciences. The whole set of working system consists of the pipe hammer air compressor, the pipe head, the earthworker, the adjusting cone, the oiler, the tensioner, the pipe system, the grouting system, the soil cleaning system, the trailer. And so on. The main specifications of the outer diameter of 42 wind-powered children 20,2513, the length of the hammer is 2400, the diameter of the pipe is 032512001. It is the largest capacity of the domestically developed pipe hammer.
2.2 Process Flow Pneumatic pipe hammer pipe laying construction main procedures are as follows: site start site survey construction design measurement stakeout work pit construction pipe mechanical installation pipe welding machine installation pipe to receiving pit clearing soil restoration site project end.
3 Engineering application 20-type pneumatic boring pipe hammer Through the practical application of this traversing project, the equipment has the characteristics of high engineering quality and short construction cost when laying large-diameter pipelines. The construction process of this project is described in detail below. 3.1 Engineering Conditions 3.1.1 Engineering The most Wuhan City Power Supply Bureau carries out the urban network transformation. For the first time, 220 high-voltage power supply is laid in the urban area. The power supply needs to cross several main traffic lines such as the Jiefang Avenue Construction Avenue on Zhongshan Road. In order not to affect the traffic and the existing environment, it is necessary to use a non-excavation method to lay power bushings.
The construction site is located at the intersection of Jiefang Avenue and Xinhua Road Youyi Road. The west side is about 50 meters. The terrain is flat, the road traffic is heavy, and there are many obstacles such as billboards on the viaduct piers, especially the trees on the sidewalks. The tree spacing is only 2.54. Meter. The north side is the site to be built by Xiehe Hospital, the south side is the site to be built by Chau International Mall, and the middle part of Jiefang Avenue is a bridge. The foundation is made of bored piles with a length of 50 meters. The site is suitable for pipe hammer construction, but requires high precision to ensure the safety of the viaduct.
3.1.2 Formation conditions According to the static penetration test results and the soil layer in the excavated work pit, the stratum characteristics of the work site are as follows. The miscellaneous fill is composed of construction waste such as cohesive soil and gravel, and the structure is loose with a layer thickness of 0.61.4 meters.
Viscous soil gray yellow soft plastic, local powder content is high, thickness 5.47.3 meters, =180901 can be divided into the following four sub-layers, one layer of clay, compacted, water loss, soil strength is good, southeast Side missing.
2 layers of clay with a constant strength and stable horizon.
3 layers of clay, sandwiched with thin layer of silt, especially the thin layer of silt in the southeast side is located at the top of the pipe.
The silt layer is mainly distributed on the north side of the site, with a maximum control thickness of 1.8 meters, = 128 groundwater level depth of 0.45.30 yang, with an average of 0.9, 1.
The pipe-piercing part is located, and the three layers are covered with thin layer of silt, and the lateral change is large. The bottom of the working pit is located at the lower part of the layer and is a relatively soft soil layer. Therefore, slope excavation and drainage prevention measures are required during excavation.
3.1.3 Underground Pipeline Distribution The construction site is located in the densely populated commercial center of Wuhan City. The underground pipelines are numerous and the relationship is complicated. The pipeline is mainly located in Zhoutian, the Jiefang Avenue section of the mall is an example of a section, and the 20-pipe steel wall is buried in the deep pipeline. The power and telecommunications water and sewage are on the slow lane and the sidewalk, and the extension direction is basically the same as Jiefang Avenue. The pipeline types include water supply pipe, telecommunications box, culvert, power trough, sewage pipe box culvert and rainwater pipe. The sewage tank culvert under the slow lane on the south side was cut with red bricks before the decade, with a width of nearly 5 meters and a bottom of 2.6 meters, and the stability was poor. When the predecessors used the directional drilling and pipelaying method to cross the Jiefang Avenue at a distance of 100 meters, a large-scale cross-bow appeared, which affected the safety of traffic and pipelines. The bottom of the water supply pipe at the north side of the fast lane is buried at a depth of 2.7 meters, and the buried depth of the underground pipelines on both sides of the sidewalk is 1.31.7 meters.
3.2 Several considerations in the construction plan, 3.2.1 夯 方法 method selection directional drilling and boring method comparison according to site construction conditions and Party A engineering requirements, combined with the directional drilling method and the boring method process characteristics, there are The following significant differences: 0 using the directional drilling machine will have the following questions. For the existing, the 8515 drilling rig has a maximum pullback force of 150KN and a torque of 3000NM. It does not have the ability to lay 16 ¢160 power bushings of 65 meters in a single hole. The use of multiple guide holes for laying separately is difficult to find a sufficiently wide construction section due to the limitation of the site. And because the stratum is soft, multiple reaming disturbs the soil, and the pavement and other structures are in danger of collapsing, which inevitably affects other existing pipelines. In addition, in order to ensure the success of pipelaying, a large amount of mud will be used in the construction, and this project will pay a huge price for the prosperous location of the construction site. Secondly, the construction period is long, it is difficult to meet Party A's requirements for the project deadline, and the engineering cost will also increase exponentially.
The underground pipeline that has the greatest impact on the construction of the manifold is mainly the sewage tank culvert located on the south side of Jiefang Avenue.
4 meters, the population is 3000, 1200 and the main water supply pipe under the north side fast lane has a top buried depth of 1.5 meters and a pipe diameter of 120,1 to ensure the safety of the existing pipeline, and determine the depth of the 820 steel pipe center. It is 4.2 meters, 1.
Union Hospital 3.2.2 fistula capacity The construction layer is a clay layer with thin layer of silt, water content is large, and the soil is soft. Refer to the cutting edge cutting pipe jacking construction method thrust calculation formula for the total thrust calculation, the total thrust required to lay the 70,1 long ga 20,1 pipe is below 210 â–¡, if the 420 type pneumatic pipe hammer is used in the working wind pressure 0.7MPa, the maximum impact force can reach 750T when the air volume is 17m3, and the working frequency is 120 minutes. Adjusting the working wind pressure or air volume can control the single impact force and impact frequency.
Yes, the selected equipment has a propulsive force greater than three times the frictional resistance of the pipeline when it is propelled forward, and its ability can meet the requirements for completing the project.
3.2.3 Calculation of the water inflow from the foundation pit According to the average pressure head height Hw from the bottom of the 2 layers, the water weight is 10Knm3. The thickness H of the bottom of the pit floor is 1 layer average residual thickness plus the layer average thickness.
The resistance coefficient 7Iy is considered based on the fact that the pit is shallow and the plane size is not large.
According to the formula 1彡7, ± heart = 4.7, 1 will not surge. That is to say, there is no pressure water surge in the foundation pit, but it is necessary to adopt the open channel drainage measures to drain the upper layer of stagnant water and precipitation of the I layer. The Ifl layer and its soil mechanics index are taken from the detailed investigation report of the geotechnical engineering of Chau International Mall at the work pit, and the geological profile data.
3.2.4 Evaluation of the foundation pit bulge Because the depth of the working pit is less than 7 meters, the east and west sides are open spaces, and only the northwest neighboring road pipelines are far from the sidewalk. The hydrogeological conditions are complex, but the groundwater has little effect on the foundation pit engineering. For the grade pit, the importance factor is 7, taking 1.
The foundation pit excavation has grading space, and the bottom slope of the pit is considered according to the simple slope without the plug-in retaining wall.
In c, according to the strength of the 1st layer of soil at the foot of the slope, the calculation of the filling and filling of the soil is larger than that of the 2l layer. The c value is equivalent to the same. 1.2 Requirements, there is no hazard at the bottom of the pit. In the formula, the partial coefficient coefficient = 245, 2. Call, 1 post, ground overload 9 take 3 = 3.2.5 Slope stability evaluation The pit slope is composed of lu soil, and the layer shear strength c9 index is used to calculate and evaluate Stable å‘», according to the slope of the first layer of 97, H, the tentative slope angle is 60 about l0.58, according to the simple soil slope of the clay soil, the stability number = 7, and = 0.153, to calculate the required cohesion, solution, 14.4 Han 3.
1813 consideration, then the safety factor, 5=1814.4=1.2, meet the stability requirements = 3.3 Construction method According to the design requirements, the entrance work pit and the exit work pit are excavated in the wall of the South Side International Shopping Mall and the North Side Union Hospital. The working pit is excavated in the wall of Chau International Shopping Mall. The working pit depth is 5 meters and the bottom inch is 16000 2000. To ensure the safety of the foundation pit, the step slope is adopted and the slope ratio is 15. The first grade slope during construction Sandbags are used for pressure protection, and the north entrance pipe is used to strengthen the support and set the drainage holes. In order to reduce the artificial disturbance to the upper layer of the bottom of the pit, 20, 1 stone is laid at the bottom of the pit, such as a sleeper and a guide rail placed on a solid cushion. Use the theodolite to measure the center line of the pipe, adjust the left and right direction of the guide rail, measure the elevation of the guide rail, adjust the horizontal angle of the guide rail according to the rising angle of 3, and stabilize the sleeper and guide rail at the bottom of the work pit. The steel pipe with the welded cutting head and the grouting nozzle is placed on the guide rail, and the tensioner is used to connect the fistula hammer taper adjusting sleeve and the end of the steel pipe to make them integral. The inlet pipe of the pipe hammer is connected to the air compressor through the pipeline system, and the grouting bin is connected with the grouting system.
Because the first section of steel pipe guides the subsequent steel pipe, it has the greatest influence on the pipelaying accuracy. Therefore, when the pipe hammer is started, the intake air volume is controlled to be small, and the steel pipe is smoothly impacted into the pit wall. Check and adjust the incident angle of the pipeline to ensure the accuracy of the manifold. After breaking into 3, 4 meters, gradually increase the working air volume to the normal value and quickly break into the steel pipe. In the manifold, two air compressors are used in parallel, and after the end of the steel pipe in the output wind section is finished, the taper and the taper head of the taper hammer are removed from the steel pipe, and moved along the guide rail to the working pit. In order to improve the construction efficiency and improve the pipe laying precision, the length of each section of steel pipe is 12 meters to reduce the number of welds. After completion, connect the upper pipe hammer to continue the pipe work until all the steel pipes are pushed into the ground.
The fistula is simultaneously and continuously grouted to the outer wall of the steel pipe to reduce the resistance of the manifold.
The diameter of the steel pipe of the Qingjing project is up to 820. If the air pressure clearing method is adopted, the energy of the compressed air is more dangerous when released. For this reason, we have chosen the artificial soil clearing method. When the soil is cleaned, the soil is manually digging into the steel pipe and the soil is pulled out with a special trolley, and attention is paid to continuous oxygen supply.
3.4 Effect This time, the 65.8-meter, 820 steel pipe was successfully completed by the fistula method. The time of the 1.71 steel pipe in the first section was 1 hour and 30 minutes, the first section was 12, 1 time was 2 hours and 40 minutes, and all the 65.8 meters were broken. The total time is 30.3 hours. After measurement, the depth of the pipeline is in accordance with the design requirements and has achieved the intended purpose.
6 Conclusions In the computer environment, geographic information systems, 40 and other geographic data products should not and continue to extend the traditional denseness of flat paper to facilitate multi-resolution large area or global seamless continuous visual positioning accurate measurement, and easy and strict Easily expand to dimensional data. Smoothly integrate existing extensive geographic data source data volumes and applications. It is the spatial mathematical foundation of the digital earth.
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