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CN-121993223-A - Tunnel primary support continuous molding system, molded concrete and construction method

CN121993223ACN 121993223 ACN121993223 ACN 121993223ACN-121993223-A

Abstract

The invention discloses a continuous molding system for tunnel primary support, molded concrete and a construction method. The self-adaptive curved surface template device of the system drives the elastic bearing plate to be attached to the irregular rock face through the telescopic oil cylinder, and realizes longitudinal sealing by utilizing the lateral sealing assembly, and is vibrated by combining an attached vibrator arranged on the back in a layered manner. The matched special concrete is doped with a delay accelerator and an early strength agent, and crushed stone aggregate with the particle size of 5-10mm is adopted, so that the unification of good workability and quick early strength is realized. During construction, an interface layer is firstly constructed by primary spraying, then layering and continuous modeling are carried out from bottom to top by using the system, and the template is intelligently controlled to move circularly according to the concrete strength development. The invention uses the cooperative innovation of the self-adaptive template system, the special concrete material and the intelligent control construction method, effectively overcomes the defects of high rebound rate, poor quality uniformity and bad operation environment of the traditional shotcrete technology, and realizes the high-precision, high-quality and green construction of the primary support.

Inventors

  • GAO XUAN
  • WANG SHUAISHUAI
  • YIN XUNJIANG
  • SUN XIANGDONG
  • TU PENG

Assignees

  • 中交第二公路工程局有限公司

Dates

Publication Date
20260508
Application Date
20260107

Claims (10)

  1. 1. The tunnel primary support continuous molding system is characterized by comprising a mobile trolley (3), a multi-degree-of-freedom mechanical arm (2) arranged on the mobile trolley (3), and a self-adaptive curved surface molding plate device (1) arranged at the tail end of the mechanical arm (2); The adaptive curved surface template device (1) comprises: a template main frame (10) hinged with the tail end of the mechanical arm (2); an elastic bearing plate (111) with a working surface for facing the surrounding rock of the tunnel; The cylinder bodies of the telescopic adjusting cylinders (112) are hinged to the main template frame (10), and the end parts of the piston rod of the telescopic adjusting cylinders are hinged to the back surface of the elastic bearing plate (111), and each telescopic adjusting cylinder (112) can independently stretch and retract to drive the elastic bearing plate (111) to elastically bend and deform so that the working surface of the telescopic adjusting cylinder is attached to an uneven tunnel excavation surface or a primary spraying surface; Each side sealing assembly comprises an adjustable side plate (122) capable of moving along the direction perpendicular to the working surface of the elastic bearing plate (111), a flexible sealing element (121) arranged at the front end of the adjustable side plate (122) and a side adjusting oil cylinder (123) for driving the adjustable side plate (122) to move; The plurality of attached vibrators (131) are fixedly arranged on the back surface of the elastic bearing plate (111) and are divided into at least two layers along the height direction of the elastic bearing plate (111).
  2. 2. The continuous tunnel preliminary bracing molding system according to claim 1, wherein the elastic bearing plate (111) is an aluminum alloy plate with the thickness of 7-10mm, reinforcing ribs are fixedly arranged on the back surface of the elastic bearing plate, the working pressure of the telescopic adjusting oil cylinder (112) is 8-12MPa, and the stroke is 50-100mm.
  3. 3. The continuous tunnel preliminary bracing molding system according to claim 1 or 2, wherein the flexible seal member (121) is a rubber plate which is connected with the adjustable side plate (122) by bolts, and an upper edge of the rubber plate contacting with surrounding rock is arc-shaped.
  4. 4. The continuous tunnel preliminary bracing molding system according to claim 1, wherein the vibration frequency of the attached vibrator (131) is adjustable within a range of 50-80Hz and the power is 1.5-2.2kW, and a plurality of attached vibrators (131) are arranged in a partitioned manner along the height direction of the elastic bearing plate (111).
  5. 5. The tunnel primary support molded concrete for the system of any one of claims 1 to 4 is characterized by comprising, by weight, 380-420 parts of ordinary Portland cement, 15-25 parts of sulphoaluminate cement, 20-35 parts of a delayed accelerator, 4-8 parts of an early strength agent, 3.2-5.0 parts of a water reducer, 160-190 parts of water, 1400-1600 parts of aggregate, wherein the aggregate is crushed stone with a particle size of 5-10 mm; The mixing amount of the delay accelerator is 5-8% of the total mass of the cementing material, the mixing amount of the early strength agent is 1-2% of the total mass of the cementing material, the mixing amount of the water reducer is 0.8-1.2% of the total mass of the cementing material, the water-gel ratio of the concrete is 0.40-0.45, the initial setting time of the concrete after vibrating is 2-4 minutes, the final setting time is not more than 9 minutes, and the compressive strength of the concrete after vibrating for 3 minutes is not less than 1.5MPa.
  6. 6. A construction method for continuous construction of preliminary support in a tunnel by using the system according to any one of claims 1 to 4, comprising the steps of: S1, constructing an interface layer, namely performing primary spraying treatment on an excavated surface by adopting a wet spraying process after tunnel excavation and installation of an initial supporting anchor rod and a steel frame to form an initial leveling interface layer; S2, positioning and sealing the template, namely moving the self-adaptive curved surface template device (1) to an initial position of an operation section, controlling the telescopic adjusting oil cylinder (112) to enable the elastic bearing plate (111) to be attached to the interface layer, and then controlling the lateral adjusting oil cylinder (123) to enable the flexible sealing element (121) to be pressed against a longitudinal rock surface of a tunnel to form a closed pouring cavity; S3, layered molding and gradient vibrating, namely pouring molded concrete into the closed pouring cavity, wherein the pouring direction is from bottom to top of arch feet at two sides of the tunnel, and starting the attached vibrator (131) in the corresponding area according to the filling height of the concrete and adopting low-frequency vibrating to lower concrete and high-frequency vibrating to upper concrete in the pouring process; S4, strength monitoring and template circulating movement, namely after the compressive strength of the poured concrete at the lower layer reaches or exceeds 1.5MPa, controlling the self-adaptive curved surface template device (1) to separate from a poured body, and moving to an adjacent non-poured section along the circumferential direction of a tunnel; S5, repeating the steps S2 to S4 until the two sides of the building body are constructed to the reserved capping area of the vault, and then pouring the capping area at a low pressure and slowly and vibrating to compact the capping area.
  7. 7. The construction method according to claim 6, wherein in step S3, the casting speed v (m 3/h) of the concrete is controlled according to the design thickness delta (dm) of the primary support according to the formula v=delta×0.12.
  8. 8. The method according to claim 6, wherein in step S3, the frequency of the low-frequency vibration is 50Hz and the frequency of the high-frequency vibration is 80Hz.
  9. 9. The method according to claim 6, wherein the template is moved in the circumferential direction at a speed of 15-25cm/min in step S4.
  10. 10. The construction method according to claim 6, wherein in step S5, the width of the reserved capping area of the vault is 30-50cm, and the self-adaptive curved surface template device (1) is kept in a compressed state for at least 3 minutes after capping pouring is completed.

Description

Tunnel primary support continuous molding system, molded concrete and construction method Technical Field The invention relates to the technical field of tunnel engineering primary support, in particular to a continuous molding system for tunnel primary support, molded concrete and a construction method. Background The primary support of the tunnel is a key link for controlling surrounding rock deformation and ensuring construction safety in tunnel engineering. At present, the primary support mode widely adopted at home and abroad is anchor spraying support, namely a combined support system combining an anchor rod, a steel arch, a reinforcing steel bar net and sprayed concrete is adopted. The concrete spraying process has the following technical defects which cannot be effectively solved for a long time: The material loss and the cost are high, the rebound rate of the concrete is generally up to 20% -30%, the serious waste of raw materials is caused, the engineering cost is increased, and the construction quantity is additionally increased due to the cleaning work of the splashed rebound materials. The uniformity of the support quality is poor, the spraying thickness depends on manual operation, the accurate control is difficult, the problems of partial excessive thickness or excessive thinness and uneven compactness are easy to occur, the strength discreteness of the support body is large, the adhesion with surrounding rock is insufficient, and the integral bearing efficiency is affected. The working environment is bad, a large amount of cement dust and mechanical noise are generated in the spraying process, the health of operators is seriously endangered, and the requirements of green and civilized construction are not met. The construction efficiency is limited by the fact that layered spraying is often required to achieve the design thickness, the process interval time is long, and the circulating operation progress is affected. In order to overcome the defects of sprayed concrete, the molding concrete process is considered as a potential alternative scheme because of the advantages of good molding quality, flat surface, high compactness and the like. However, conventional molding processes (commonly found in secondary lining of tunnels) cannot be directly applied to primary support because: The application stage is different in that the existing molding technical specifications (such as DB 15/T4023-2025) are definitely specific to the construction of the permanent concrete lining (namely the secondary lining) of the hydraulic pressureless tunnel, and the premise is that the existing stable primary support is taken as an internal mold foundation. The invention aims at the primary support which is immediately implemented after excavation and directly attached to unstable surrounding rock. The technical requirements are contradictory that the surface of the surrounding rock of the primary support is uneven, and the support force is required to be provided rapidly. The traditional rigid template cannot be attached to an irregular rock surface, a large number of holes exist, and the casting thickness and the surface flatness are difficult to ensure by adopting the flexible template. Meanwhile, early-strength and rapid hardening of concrete are required for early-strength and rapid stabilization of surrounding rock, which are contradictory to concrete workability and vibratable time required by a molding process. In recent years, there have been studies on improving lining technologies, for example, adopting a "partially prefabricated, semi-post-cast" steel fiber concrete (SFRC) and self-compacting concrete (SCC) composite lining system to improve construction efficiency and quality, or exploring the use of SFRC for shield segments, but these studies have focused on secondary lining or prefabricated assembly structures, the core of which is to solve the problems of quick installation, joint performance or durability of permanent lining, without touching the fundamental difficulty of directly performing high-precision, quick molding on rugged excavated rock faces. Therefore, an innovative continuous molding concrete construction technology special for tunnel primary support is needed in the industry, and the self-adaptive close adhesion of the template and the irregular surrounding rock surface and the rapid early strength and accurate molding of concrete can be realized, so that the inherent defects of the traditional injection technology are fundamentally overcome. Disclosure of Invention The invention aims to provide a tunnel primary support continuous molding system, molded concrete and a construction method, and aims to solve the technical problems of high rebound rate, uneven quality and great environmental influence of the traditional sprayed concrete. The core aim is to realize continuous, high-precision and rapid molding of the primary support structure through a set of cooperative system integrated