At present, tunnel lining construction has changed from manual operation to comprehensive mechanization, and improving tunnel lining quality and working efficiency is the greatest demand of construction. Trolley is a one-step molding equipment for concrete lining of railway and highway tunnels. Design and manufacture according to the tunnel section provided by users can ensure that excavation and lining can be carried out at the same time. The clearance height and width of the portal frame can ensure the passage of rail and trackless transport vehicles. The whole machine is driven by a motor; The formwork is controlled by full hydraulic pressure, and the hydraulic cylinder locks the formwork mechanically. A space for installing tunnel ventilation pipes is reserved between the upper part of the platform frame and the formwork; For the tunnel lining with gas, the electrical system of the product is designed and installed according to the requirements of the Explosion-proof Code for Gas Tunnels to ensure the safety of use.
The railway and highway lining trolley developed by Taiyuan Road and Bridge Machinery Factory has been widely used in many tunnel projects.
1, lining trolley
The development process of 1. 1
Gan Long Railway Tunnel is more than 2,000 meters long, with karst caves, mudstone and groundwater, and its geological conditions are harsh and complicated. On the basis of extensive market research, Taiyuan Road and Bridge Machinery Factory established the "Tunnel Lining Trolley Development Team" and invited experts from relevant engineering units to give guidance. On the basis of the design and calculation of the preliminary drawings and technical documents of the railway tunnel lining trolley, according to the cross-sectional drawings and construction requirements of the tunnel provided by the construction unit and the development trend of the tunnel lining trolley, after optimization and comparison and approval by users, the design and product trial-production will be organized. In order to ensure the processing quality of products, important structures are strictly controlled by tooling and molds. The application shows that the product has good performance, reasonable structure and good lining quality. After repeated improvement and perfection, the product has been finalized.
1.2 key technology of steel formwork lining trolley
1.2. 1 trolley structure type
Hydraulic type and mechanical type can be used. Through analysis and comparison, the hydraulic platform frame has low requirements for rigidity, flexible structure, light weight, low requirements for processing and track laying elevation during construction and convenient use, but high requirements for self-locking of hydraulic cylinders, and the hydraulic cylinders in the lining are not allowed to retract. However, the mechanical type requires high coaxiality of each drive shaft because one motor drives several screw shafts, and the platform frame must have greater rigidity and accurate structural dimensions. Because the structure is bulky, the processing requirements are high, and because the screw shafts are synchronous (unlike hydraulic transmission, each hydraulic cylinder can act synchronously or independently), when the track elevation error (each point is not at the same elevation) is large, it will directly affect the template position, thus affecting the lining quality. After analysis and comparison, the hydraulic transmission scheme is selected, and measures such as hydraulic lock and balance valve are taken to make the hydraulic cylinder self-lock. At the same time, the screw mechanism is used for mechanical locking to strengthen the support of the formwork and ensure that the formwork does not shrink and deform during lining. Practice has proved that the hydraulic lining trolley is reasonable and is the development direction.
1.2.2 structural optimization of vehicle frame
The trolley adopts hydraulic transmission, which simplifies the structure of the platform frame, reduces the weight and improves the flexibility and diversity of the structure. Through the analysis, comparison, strength calculation and optimization of various platform frame structural schemes, the structural scheme of 9m four-door gantry 12m main gantry is selected, which reduces the structural weight by more than 40% and the manufacturing cost by more than 25%.
1.2.3 steel mould
Steel formwork is the working device of trolley, and its appearance quality and dimensional accuracy directly determine the quality of concrete lining, and it is also the most difficult part to process. The reasonable processing and welding technology is formulated, and the special assembly welding tire mold is designed and processed, which ensures the accuracy of the external dimensions, minimizes the welding deformation, and ensures the smooth external surface without concave and convex defects. In order to control the dislocation of adjacent templates, the connecting plates of adjacent templates are fixed into a whole by stable pins with interference fit, which effectively controls the dislocation of adjacent templates caused by bolt hole clearance. After successfully solving the above problems, the quality of concrete lining is guaranteed.
1.2.4 Determination of supporting position
The quality of lining concrete is all transferred to the supporting mechanism through the trolley steel formwork, and then to the portal frame. The lining concrete is in a solid-liquid state, which produces great vertical pressure and lateral pressure at the top and side, and at the same time produces great buoyancy. When the buoyancy of the upper part exceeds the vertical pressure and the weight of the car, the car will float and cannot work normally. In order to solve this technical problem, after careful calculation, optimized design and reasonable selection of support positions. That is, the lower longitudinal beam at the inner side of the portal frame is supported by the ground to prevent the portal frame column from collapsing due to lateral pressure. There are several horizontal supports at the outer side of the portal frame and the longitudinal beam of the side formwork, and several vertical supports at the upper beam and the upper longitudinal beam of the portal frame (top hydraulic cylinders are arranged at the transverse parts of the portal frames at both ends, and vertical support screws are arranged in the middle), which are evenly distributed along the longitudinal direction of the trolley. The hydraulic cylinder is locked by hydraulic lock and the supporting screw is locked mechanically to ensure that the hydraulic cylinder does not retract and the formwork does not deform during lining construction.
2. Main technical parameters of steel formwork lining trolley
3. Main structure and working principle
The trolley consists of six parts: walking mechanism, platform frame, steel formwork, formwork vertical lifting and lateral telescopic mechanism, hydraulic system and electrical control system.
1. Side template
2. Top template
3. Upper longitudinal beam
4. Vertical lifting mechanism (top hydraulic cylinder and vertical support screw)
5. Transverse hydraulic cylinder and transverse support screw Ⅰ
6. Lateral support screw Ⅱ
7. Lateral support screw Ⅲ
8. Portal posts
9. Rigid frame beam
10. Walking mechanism
1 1. Lower support screw
3. 1 walking mechanism
The walking mechanism consists of an active part and a passive part. ***4 sets of devices are respectively installed at the lower end of the gantry column at both ends of the gantry. The whole machine adopts two sets of active walking mechanisms, that is, the walking motor drives the reducer, the driving wheel drives the whole machine through chain transmission, and the passive wheel follows. The traveling transmission mechanism is equipped with a hydraulic push rod brake to ensure that the whole machine can still park safely on the ramp.
3.2 framework
The platform frame consists of an end gantry, a middle gantry, upper and lower longitudinal beams, diagonal tie rods and support rods. All parts are connected into a whole by bolts. Gantries at both ends are supported on the walking wheel frame, and the lower end of the middle gantry is equipped with supporting screws. During lining construction, the concrete load is transferred to the four portal frames through the formwork, and then transferred to the track ground through the walking wheels and supporting screws respectively. When walking, the screw should be retracted, and the front section of the upper part of the gantry is equipped with an operating platform for placing hydraulic and electrical devices.
3.3 template
Formwork is a working part directly lining concrete, which is composed of several top formworks and side formworks connected by bolts. The top die and the side die are hinged, and the side die can rotate around the pin shaft relative to the top die. When supporting the formwork, the top hydraulic cylinder extends the top formwork into place, and then the side hydraulic cylinder is manipulated to extend the side formwork into place, and the top bracing and side bracing screws are adjusted to complete the formwork support. When closing the mold, it should be carried out in the reverse order mentioned above. There is no need to dismantle the formwork, and the lining trolley is adopted to improve the lining quality and construction efficiency and reduce the labor intensity. In addition, several attached vibrators are installed on the top formwork for vibrating concrete, and each formwork has a working window for pouring concrete.
3.4 Hydraulic system
It consists of motor, hydraulic pump, manual reversing valve, vertical and lateral hydraulic cylinders, hydraulic lock, oil tank and pipeline, and its function is to support and retract the mold quickly and conveniently, that is, to lift the upper mold and support the side mold. Manual reversing valves respectively control the vertical lifting of the formwork and the lateral expansion and contraction of the formwork on both sides. When the formwork is supported in place by the hydraulic cylinder, the supporting screw is adjusted, and the vertical and lateral loads caused by pouring concrete on the formwork are mainly borne by the hydraulic cylinder and the screw.
4. Analysis and evaluation of engineering application and trolley lining effect
4. 1 engineering application
Trolley has been widely used in Gan Long Tunnel, Yuyuan Highway Tunnel, Jinji Highway Tunnel, Baolan Single-track Railway Tunnel, neijiang-kunming railway Tunnel, Southwest Railway Tunnel, Qinghai-Tibet Railway Tunnel and other projects, with good performance, reasonable structure and good lining quality.
4.2 lining effect analysis
(1) When the tunnel excavation deviates from the center, it can be adjusted by the formwork adjustment mechanism of the trolley to meet the design and construction requirements.
(2) The trolley has sufficient rigidity and strength, and can resist the strong vertical and lateral pressure of concrete under the joint action of the hydraulic cylinder and the supporting screw, and the trolley is not deformed. Due to the reasonable design and layout of each fulcrum, the self-weight of the trolley and the pressure of concrete weight are effectively utilized, which ensures that the trolley can overcome the floating effect of concrete when pouring mixed soil.
(3) The layout of the working window is reasonable, the concrete pouring and vibrating operation on both sides are convenient, and the top is provided with a material injection port and an auxiliary vibrator, which is convenient for concrete pouring without manual tamping, thus reducing the labor intensity of construction personnel.
(4) The joints of large steel formwork are sealed, the concrete tamping facilities are complete, the concrete is dense without honeycomb, spots and dislocation, and the surface is smooth, flat and beautiful.
4.3 Innovation and progress
The optimized design of (1) frame not only ensures sufficient strength and rigidity, but also has simple structure, light weight and beautiful appearance.
(2) The hydraulic system adopts hydraulic lock, balance valve and other measures to lock the hydraulic cylinder, and at the same time adopts spiral mechanical lock. This "double lock" ensures that the formwork will not be deformed or displaced in the lining state, strengthens the supporting rigidity of the formwork and reduces the structural weight of the formwork.
The successful development of steel formwork lining trolley for railway and highway tunnels is a major breakthrough to the traditional tunnel lining construction method. The longest primary lining length can reach 12m. Mechanized concrete spraying, the lining efficiency is dozens of times that of traditional construction methods, which can save a lot of manpower and material resources and improve workers' working conditions. Trolley can be widely used in lining construction of long and short tunnels. At the same time, the traffic of vehicles during lining and excavation does not interfere with each other and can be operated at the same time. Its comprehensive performance has reached the domestic advanced level, which has good economic and social benefits and can be widely popularized.
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