A lining leakage water prevention and treatment method suitable for straight thin middle wall connected arch tunnel
By constructing a waterproofing and drainage system inside and outside the tunnel, the problem of water leakage at the top of the central wall of the straight thin central wall continuous arch tunnel was solved, achieving comprehensive prevention and control of water leakage, ensuring the safety and reliability of the tunnel structure, and reducing the risk of water leakage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA TIESIJU CIVIL ENGINEERING GROUP CO LTD
- Filing Date
- 2023-11-07
- Publication Date
- 2026-05-19
AI Technical Summary
In traditional twin-arch tunnels, the waterproofing layer at the top of the central wall is difficult to lay and prone to leakage, especially in areas with high groundwater levels or complex geology. Existing waterproofing and drainage measures cannot effectively solve the leakage problem of the thin central wall and increase the project cost and construction complexity.
A complete drainage system was constructed inside and outside the tunnel, including side ditches and underground drainage ditches on both sides of the tunnel. Double-walled corrugated pipes with half-perforated holes were used to connect the transverse drainage blind pipes. A central wall drainage pipe was installed on the top of the central partition wall. A circumferential drainage strip was used to lead the water to the underground drainage ditch. Waterstops and waterproof layers were installed at key locations. High-performance waterproof concrete and waterproof boards were used to ensure the effective discharge of leaking water.
This creates an effective drainage structure in the central partition wall, improving the drainage capacity at the top of the partition wall, preventing water from seeping into the interior of the lining structure, reducing the accumulation of seepage water, ensuring the stability and service life of the tunnel structure, and reducing the risk of water leakage.
Smart Images
Figure CN117627689B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of tunnel lining leakage prevention technology, specifically relating to a method for preventing leakage in the lining of a straight, thin-walled, continuous-arch tunnel. Background Technology
[0002] Compared to two single-arch tunnels, twin-arch tunnels offer advantages such as lower cost and smaller footprint, leading to their increasingly widespread application. However, traditional twin-arch tunnels employ a monolithic straight central wall structure. The top of the central wall is lower than the two side arches, creating a longitudinal seam at the arch-wall junction, resulting in a weak point in waterproofing. The limited space at the top of the central wall makes waterproofing layer installation difficult, compromising construction quality. Furthermore, the recessed area at the top of the central wall provides a breeding ground for groundwater, exacerbating leakage problems, especially in areas with high groundwater levels or complex geological conditions. Therefore, developing an effective drainage system is one of the key issues to be addressed in tunnel construction.
[0003] Chinese patent CN101519969B discloses a double-partitioned, twin-arch tunnel. By replacing the central partition wall with a double partition wall and using drainage holes to allow water to drain into the drainage ditch at the bottom of the central tunnel formed between the two partition walls, the leakage problem of twin-arch tunnels is solved. However, this double partition wall undoubtedly increases the overall width of the central partition wall, increasing the project cost and the land occupied outside the tunnel, and the construction steps are more complex than those of conventional central partition walls. Furthermore, the waterproofing measures of this central partition wall are not suitable for thin, straight central partition walls with small design widths, and traditional waterproofing methods for central partition walls cannot effectively solve the leakage problem of this special structure. Summary of the Invention
[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preventing water leakage in the lining of a straight, thin-walled, arched tunnel.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] A method for preventing water leakage in the lining of a thin-walled, arched tunnel is proposed, which involves constructing a complete and unobstructed drainage system both inside and outside the tunnel. The method includes the following steps:
[0007] Step 1: Construct roadside ditches and drainage culverts on both sides of the tunnel driving lane. The drainage culverts on both sides are connected by transverse drainage blind pipes. The transverse drainage blind pipes are double-walled half-perforated corrugated pipes.
[0008] Step 2: After the central tunnel is constructed, the central partition wall is constructed. The cavity at the top of the central partition wall is backfilled with mortar-grouted rubble to form an arched top. Longitudinal drainage pipes are installed at the corners of both sides of the tunnel roadway. These longitudinal drainage pipes are double-walled, half-perforated corrugated pipes. A central wall drainage pipe is installed longitudinally at the shoulder of the central partition wall. This central wall drainage pipe is also a double-walled, perforated corrugated pipe. In areas with seepage after tunnel excavation, a circumferential drainage strip is laid along the rock surface. This circumferential drainage strip is a semi-circular drainage pipe. The end of the circumferential drainage strip closest to the central partition wall is connected to the central wall drainage pipe. The end of the circumferential drainage strip furthest from the central partition wall is drained into a drainage ditch through a transverse water guide pipe. This transverse water guide pipe is a double-walled corrugated pipe.
[0009] Step 3: Lay a waterproof layer between the initial support and the secondary lining as the first waterproofing measure; use waterproof concrete of not less than P8 for the secondary lining of the arch and sidewalls as the second waterproofing measure; install circumferential drainage pipes at intervals on the surface of the initial support, and use flexible permeable pipes for the circumferential drainage pipes; connect the drainage pipes of the central wall to the circumferential drainage pipes, and connect the two ends of the circumferential drainage pipes to the longitudinal drainage pipes on the back wall of the tunnel on both sides respectively, and then introduce water into the drainage ditch and discharge it outside the tunnel through the transverse water guide pipe.
[0010] Furthermore, the method for preventing water leakage in the lining of a thin-walled arch tunnel also includes waterproofing construction at the tunnel entrance: before excavation of the slope at the tunnel entrance, a water interception ditch is laid out along the terrain 5m away from the tunnel entrance, the side of the open tunnel, and the slope brush line, to divert surface runoff into natural valleys or temporary drainage systems; the water interception ditch is rectangular and is poured with C20 concrete; to prevent uneven settlement of the tunnel roof from damaging the water interception ditch, a settlement joint is set every 10m of the water interception ditch, with a joint width of 2cm, and the settlement joint is filled with asphalt hemp rope.
[0011] Furthermore, the lining concrete is produced by an automatic concrete metering and mixing plant, transported by concrete mixer trucks, and poured by concrete pumps. The lining is constructed using a full-section hydraulic lining trolley. The invert arch of the entire tunnel is constructed in advance, and the lining follows closely behind. The secondary lining arch, invert arch, and outer sidewalls are constructed with 60cm thick reinforced concrete in Class V surrounding rock sections and 50cm thick reinforced concrete in Class IV surrounding rock sections. The inner sidewalls are all constructed with 50cm thick reinforced concrete. The central partition wall is constructed with 150cm thick reinforced concrete.
[0012] Furthermore, the waterproof layer includes a 1.5mm thick EVA waterproof membrane and 350g / m³ waterproofing material. 2 Non-woven fabric; embedded rubber waterstops and grouting pipe expansion waterstops are installed at the construction joints of the secondary lining for water sealing, and back-adhesive rubber waterstops and embedded rubber waterstops are installed at the expansion joints for water sealing.
[0013] Furthermore, the method for preventing water leakage in the lining of a thin-walled, continuous-arch tunnel also includes drainage construction in the open-cut section: In the open-cut section, the outer layer of the lining is covered with a two-layer geotextile and one-layer membrane waterproofing layer and a 2cm thick cement mortar protective layer. The backfill soil and rock bottom layer uses a backfill drainage pipe to remove seepage water; the backfill drainage pipe is a Φ100mm HDPE corrugated pipe. The two-layer geotextile and one-layer membrane waterproofing layer is made of geotextile (350g / m²). 2 ) + 1.5mm thick EVA waterproof membrane + geotextile (350g / m) 2 The structure includes a clay waterproofing layer on the backfill surface of the tunnel to prevent surface runoff from seeping in. The clay waterproofing layer has a slope, and drainage ditches are set at the low-lying areas at both ends of the clay waterproofing layer. Surface runoff flows into the drainage ditches under the action of the clay waterproofing layer and is discharged away. In terms of structural waterproofing, embedded rubber waterstops and back-adhesive rubber waterstops are used at the construction joints and expansion joints of the tunnel. At the same time, the structure uses waterproof concrete with a seepage prevention grade of not less than P8 to form a complete waterproofing and drainage system for the tunnel.
[0014] Furthermore, the tunnel lining is constructed using C35 reinforced concrete with a permeability grade of not less than P8. After the tunnel lining construction is completed, a 3cm thick M10 cement mortar leveling layer is poured on the outer surface of the lining. A two-layer waterproof layer and a cement mortar protective layer are then laid on the leveling layer, followed by backfilling with grouted rubble masonry and crushed stone. The grouted rubble masonry is backfilled on both sides first, followed by crushed stone backfilling, proceeding symmetrically in layers from bottom to top according to the design. The backfill soil should be compacted in layers. The height difference between the backfill surfaces on both sides should not exceed 0.5m. The thickness of each layer compacted manually should not exceed 0.25m, and the thickness of each layer compacted mechanically should not exceed 0.3m. After the tunnel backfilling is completed, timely greening and protection work should be carried out at the tunnel entrance and the tunnel top. The tunnel top backfilling is protected by spraying grass, the slope above the backfill top surface is protected by planting climbing vines, the uphill slope is temporarily protected by anchor spraying, and the uphill slope above the backfill surface is permanently protected by anchor frame planting grass to prevent rainwater erosion.
[0015] Furthermore, the circumferential drainage pipes are made of Φ50mm flexible permeable pipes, which are generally laid evenly along the initial support surface in the longitudinal direction, with an average of one pipe every 10m. In water-rich sections of Class V surrounding rock, the spacing is increased to one pipe every 5m. In areas with seepage in strands after tunnel excavation, 1 to 3 Φ100mm circumferential drainage strips are laid along the rock surface. To ensure that the semi-circular drainage pipes are in close contact with the rock surface, 2 to 5cm thick concrete is sprayed before laying the semi-circular drainage pipes after tunnel excavation. In areas with particularly severe seepage in strands, Φ50mm PE single-wall non-porous corrugated pipes can be used to directly drain the water into the lateral drainage ditch.
[0016] Furthermore, the drainage ditch on the left side of the driving direction is 40cm wide and 40cm deep, while the drainage ditch on the right side of the driving direction is 60cm wide and 35cm deep. The top of the drainage ditch is covered with a C30 precast reinforced concrete cover plate, and the roadside ditch is set on the C30 precast reinforced concrete cover plate. The transverse drainage blind pipes are Φ100mm and are set at intervals of 10m along the longitudinal direction of the tunnel, and are set at the circumferential construction joint of the invert arch as much as possible to drain the water on the road surface. The transverse drainage blind pipes, circumferential drainage pipes, and longitudinal drainage blind pipes behind the wall are all wrapped with non-woven geotextile to prevent cement or soil from clogging the pipes and to ensure smooth drainage.
[0017] Furthermore, the longitudinal drainage pipe behind the wall is Φ100mm and is installed along the bottom of the tunnel. Its slope is consistent with the longitudinal slope of the tunnel. The longitudinal drainage pipe behind the wall is disconnected and plugged at the intersection of each transverse tunnel and the main tunnel. The transverse water guide pipe and the circumferential drainage pipe are connected to the longitudinal drainage blind pipe behind the wall by tees.
[0018] Furthermore, a sedimentation well is set up every 30m in the drainage ditch. All sedimentation wells are underground and also serve as inspection wells.
[0019] The beneficial effects of this invention are:
[0020] This invention enables the concentrated drainage of seepage water from the surrounding rock by setting an annular drainage strip at the threaded part of the surrounding rock, reducing the impact of seepage water from the surrounding rock on the central partition wall during the initial support stage. At the same time, a central wall drainage pipe is set at the shoulder of the top of the central partition wall. The central wall drainage pipe adopts a double-wall perforated corrugated pipe, which can drain the groundwater in the groove at the top of the central wall, forming an effective drainage structure for the central partition wall. This improves the drainage capacity of the top of the central partition wall, and the drainage structure of the central partition wall does not affect the reinforced concrete structure of the central partition wall itself, ensuring the integrity of the central partition wall and facilitating the maintenance of the stress and overall stability of the central partition wall. This solves the problem of waterproofing and drainage of thin, straight central partition walls with a small design width.
[0021] This invention establishes a complete and unobstructed drainage system both inside and outside the tunnel, preventing water from seeping into the tunnel from the surrounding underground. The use of separate waterproofing membranes in the tunnel lining effectively prevents moisture from penetrating the lining structure. Waterstops are installed at key locations within the tunnel to effectively prevent water from seeping into the tunnel through these gaps. The construction of various drainage pipes effectively collects and discharges accumulated water inside the tunnel, thereby reducing the accumulation of seepage water. This method achieves comprehensive prevention and control of water leakage in straight, thin-walled, multi-arch tunnels, ensuring the safety of the tunnel structure while mitigating potential damage caused by water leakage, thus improving the tunnel's reliability and service life. These measures work together to effectively reduce the risk of tunnel water leakage and ensure the long-term stability of the tunnel. Attached Figure Description
[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:
[0023] Figure 1 This is a comprehensive layout diagram of the double-arch tunnel drainage system of the present invention.
[0024] Figure 2 This is a plan view of the drainage system at the opening of the present invention.
[0025] Figure 3 This is a schematic diagram showing the connection between the horizontal water guide pipe and the longitudinal drainage blind pipe behind the wall according to the present invention.
[0026] Figure 4 This is a schematic diagram of the structure of the circumferential drainage blind pipe and the longitudinal drainage blind pipe behind the wall according to the present invention.
[0027] Figure 5 This is a comprehensive layout diagram of the drainage system of the right tunnel of the present invention.
[0028] Figure 6 for Figure 5 Enlarged diagram of point A in the middle.
[0029] Figure 7 for Figure 5 Schematic diagram of the cross section in the middle II direction.
[0030] Figure 8 This is a schematic diagram of the construction of the semi-circular drainage pipe of the present invention.
[0031] Figure 9 This is a schematic diagram of the construction of the horizontal drainage blind pipe of the present invention.
[0032] Figure 10 for Figure 9 Enlarged diagram of point C in the middle.
[0033] Figure 11 This is a diagram showing the arrangement of the rubber waterstop at the deformation joint of the tunnel body according to the present invention.
[0034] Figure 12 This is a schematic diagram of the installation of the rubber waterstop at the deformation joint of the tunnel body according to the present invention.
[0035] Figure 13 This is a diagram showing the arrangement of the rubber waterstop at the construction joint of the tunnel body according to the present invention.
[0036] Figure 14 This is a schematic diagram of the installation of the rubber waterstop at the construction joint of the tunnel body according to the present invention.
[0037] Figure 15 This is a schematic diagram illustrating the construction process of laying the waterproof membrane according to the present invention.
[0038] Figure 16 This is a flowchart illustrating the overall tunnel construction process according to an embodiment of the present invention.
[0039] Figure 17 This is a flowchart illustrating the construction process of waterproofing and drainage for a tunnel according to an embodiment of the present invention.
[0040] Figure 18 A cross-sectional view of the lining structure of the open-cut section of the tunnel according to an embodiment of the present invention.
[0041] Figure 19 for Figure 18 Schematic diagram of the waterproof layer in the open section of the central tunnel. Detailed Implementation
[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art are within the scope of protection of the present invention.
[0043] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.
[0044] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.
[0045] This embodiment uses a series of arch tunnels on a highway as an example. The highway is classified as a mountain highway, and the tunnel's starting and ending points are K12+900 to K13+250. It is a series of arch tunnels with a design speed of 100 km / h. The entrance is at K12+900, and the exit is at K13+250, with a total length of 350m. The maximum burial depth is approximately 70m. The tunnel is located entirely on a curved section with a radius of curvature of 4000m. A 0.5% uphill slope is set from the entrance to K12+950, and a 2.2% uphill slope is set from K12+950 to the exit. The maximum cross-sectional area is 337.4m². 2The tunnel has a total length of 175m in both Class V and Class IV surrounding rock. The standard cross-section of the tunnel is as follows: the tunnel arch and outer sidewalls are made of circular arcs with a radius of 800m, the invert arch is made of a large-radius circular arc with a radius of 2000cm, and they are connected by small-radius circular arcs with a radius of 120cm. The inner sidewalls are straight.
[0046] Building clearance: Clear width: 2*[0.25 (extra width) + 0.75 (left side width) + 3*3.75 (driving lane) + 1.0 (right side width) + 0.75 (right maintenance lane)] + 2.7 (central partition wall) = 30.7m; Clear height: 5.0m; Design load: Highway Class I; Waterproofing grade: Class II. Figure 16 This is a flowchart of the overall construction process for the tunnel.
[0047] like Figures 1 to 15 As shown, the tunnel waterproofing system consists of:
[0048] ① Lay a 1.5mm thick EVA waterproof membrane + 350g / m² between the secondary lining and the initial support. 2 Non-woven fabric;
[0049] ② At the construction joint of the secondary lining, embedded rubber waterstops and grouting pipe expansion waterstops are installed for water sealing, and at the expansion joints, back-adhesive rubber waterstops and embedded rubber waterstops are installed for water sealing.
[0050] ③ Self-waterproofing of lining concrete and secondary lining concrete: The lining concrete is produced by an automatic concrete metering and mixing plant, transported by concrete mixer trucks, and poured by concrete pumps. The lining adopts a full-section hydraulic lining trolley. The invert arch of the entire tunnel is constructed in advance, and the lining follows closely. The secondary lining arch, invert arch and outer sidewalls are poured with 60cm thick reinforced concrete in Class V surrounding rock sections and 50cm thick reinforced concrete in Class IV surrounding rock sections. The inner sidewalls are all poured with 50cm thick reinforced concrete. The central partition wall is poured with 150cm thick reinforced concrete.
[0051] like Figures 1 to 15 As shown, the drainage system consists of:
[0052] ① Trapezoidal longitudinal open roadside ditches are set on both sides of the tunnel surface to drain sewage from operation and cleaning, fire fighting and road surface water;
[0053] ②The main drainage system, consisting of circumferential drainage pipes, longitudinal drainage blind pipes behind the wall, transverse water guide pipes, transverse drainage blind pipes and roadside culverts, is mainly used for centralized diversion and drainage of groundwater.
[0054] ③ The drainage structure at the top of the middle wall, consisting of a circumferential drainage strip, a drainage pipe in the middle wall, and a vertical guide pipe installed close to the rock surface, is connected to the main drainage system and is used to drain seepage water from the top of the middle partition wall.
[0055] The following will combine Figures 1 to 19The present invention will now be described in detail.
[0056] like Figures 1 to 19 As shown, a method for preventing water leakage in the lining of a thin-walled, multi-arched tunnel is proposed. This method follows the principles of "combining prevention, drainage, interception, and plugging; adapting to local conditions and comprehensive management," ensuring the normal operation of the tunnel structure and equipment, and ensuring traffic safety; protecting the natural environment, preventing surface water loss and groundwater pollution, and forming a complete and unobstructed drainage system inside and outside the tunnel; it includes the following steps:
[0057] Step 1: Waterproofing Construction at the Tunnel Entrance: Water accumulation should be avoided at the tunnel entrance area to prevent erosion of the entrance in summer and frost heave damage to the entrance foundation in winter. Before excavation of the slope at the entrance, intercepting ditches should be laid along the terrain 5 meters away from the tunnel entrance, the side of the open tunnel, and the slope sloping line to divert surface runoff into natural valleys or temporary drainage systems. For example... Figure 2 The image shows the intercepting ditch set at the tunnel entrance. The intercepting ditch is rectangular and is constructed with C20 concrete. To prevent uneven settlement of the tunnel roof from damaging the intercepting ditch, a settlement joint with a width of 2cm is set every 10m of the intercepting ditch, and the settlement joint is filled with asphalt hemp rope. Roadbed water at the tunnel entrance is strictly prohibited from flowing into the tunnel. If necessary, a reverse slope can be set.
[0058] like Figures 1 to 6 As shown, the construction roadside ditches and drainage ditches are located on both sides of the tunnel driving lane. The drainage ditches on both sides are connected by transverse drainage blind pipes, which are double-walled half-perforated corrugated pipes.
[0059] Step Two: After the pilot tunnel construction is completed, the foundation of the pilot tunnel is cleared from the tunnel entrance to the exit. Foundation clearing is carried out manually in conjunction with machinery. The foundation elevation is 10cm lower than the design structural bottom elevation. During foundation clearing, strict control is maintained according to the data provided by the surveyors. Over-excavated areas are backfilled with C20 plain concrete, compacted and leveled to ensure foundation stability. After foundation clearing, a 10cm thick C25 concrete subbase is constructed. Following the subbase construction, the central partition wall is constructed. In this embodiment, the central partition wall formwork uses a formwork trolley, which is 10m long. The formwork trolley is assembled from steel formwork and steel back braces, utilizing directional... The concrete is moved using pulleys; the overlap length between each pour and the previous pour is no less than 10cm, and wooden formwork is used to seal the ends; steel formwork is used for the partition wall, and the formwork is processed by a professional manufacturer; C35 concrete is used for the partition wall pouring, transported by concrete mixer truck, and pumped for construction. The concrete is poured in layers with a thickness not exceeding 30cm, and compacted with an immersion vibrator; due to the limited working space, the concrete pouring of the partition wall is carried out unidirectionally from the outlet to the inlet, using pumped concrete, with one cycle every 10m; the construction joint is the weakest point of the partition wall, and it must be roughened each time, and the pre-embedded connecting steel bars should be installed strictly according to requirements.
[0060] There are two common methods for backfilling the cavity at the top of the partition wall: one is to use graded crushed stone grouting, and the other is to use shotcrete or cast-in-place concrete. Considering that the above two methods are prone to causing blockage of the drainage structure of the partition wall, they are not used during construction. This embodiment adopts the method of backfilling the cavity at the top of the partition wall with mortar-grouted rubble masonry. During backfilling, the filling should be compacted, and there should be no gaps between the top of the cavity and the backfill layer.
[0061] like Figures 1 to 5 As shown, longitudinal drainage pipes are installed at the corners of both sides of the tunnel's driving lane, and longitudinal drainage pipes are installed at the top shoulder of the central partition wall. For areas with seepage after tunnel excavation, a Φ100mm semi-circular drainage strip is laid along the rock surface. The end of the drainage strip closest to the central partition wall is connected to the central partition wall drainage pipe, which is a double-wall perforated corrugated pipe. Besides draining seepage from the drainage strip, it also collects seepage accumulated at the shoulder of the central partition wall. The drainage strip is connected to the central partition wall drainage pipe via a tee, and a vertical guide pipe is connected to the drainage strip via a tee. The end of the drainage strip furthest from the central partition wall is drained to a drainage ditch via a transverse guide pipe, thus draining seepage and accumulated water at the shoulder of the central partition wall.
[0062] Step three includes waterproofing and drainage construction for both the culvert and the open section of the tunnel; such as Figure 17 The diagram shown is a flowchart of the structural waterproofing and drainage construction process.
[0063] (1) Construction of drainage and waterproofing for tunnel culverts
[0064] like Figures 1 to 15 As shown, in order to effectively drain water behind the secondary lining and eliminate hydrostatic pressure behind the secondary lining, a circumferential drainage pipe is installed at a 10m interval between the initial support and the waterproof layer. The circumferential drainage pipe is a Φ50mm flexible permeable pipe, and the drainage pipe in the central wall is a Φ100mm double-wall perforated corrugated pipe. The central wall drainage pipe is connected to the circumferential drainage pipe, and the two ends of the circumferential drainage pipe are connected to the longitudinal drainage pipes on the back of the walls on both sides of the tunnel. Then, water is introduced into the drainage culvert through the transverse water guide pipe. The drainage culvert and the roadside ditch are connected to the roadbed drainage ditch outside the tunnel.
[0065] A waterproof layer is laid between the initial support and the secondary lining as the first waterproofing measure; the waterproof layer includes a thick EVA waterproof board and non-woven fabric.
[0066] The secondary lining of the arch and sidewalls uses waterproof concrete of not less than P8 as a second layer of waterproofing.
[0067] The expansion joints of the cast-in-place concrete in the tunnel body are equipped with back-adhesive rubber waterstops and embedded rubber waterstops. The circumferential construction joints of the deep-buried section of the tunnel body are equipped with back-adhesive rubber waterstops and embedded rubber waterstops, and the longitudinal construction joints are equipped with embedded rubber waterstops to ensure the waterproof effect at the construction joints and expansion joints.
[0068] (2) Drainage and waterproofing construction of open-cut tunnel section
[0069] like Figure 18 , 19 As shown, after the tunnel lining construction is completed, a 3cm thick M10 cement mortar leveling layer is poured on the outer surface of the lining. A two-layer waterproofing layer and a cement mortar protective layer are then laid on the leveling layer, followed by backfilling with grouted rubble masonry and crushed stone. The grouted rubble masonry is backfilled on both sides first, followed by crushed stone, proceeding symmetrically in layers from bottom to top, according to the design. The backfill soil should be compacted in layers. The height difference between the backfill surfaces on both sides should not exceed 0.5m. The thickness of each layer compacted manually should not exceed 0.25m, and the thickness of each layer compacted mechanically should not exceed 0.3m. C15 plain concrete is used for the invert arch backfill. The maximum backfill height at the tunnel top should not exceed 6m and should not be less than 1.5m, with a compaction degree of not less than 90%. %; After the tunnel backfilling is completed, timely greening and protection work is carried out at the tunnel entrance and top. The tunnel top backfill is protected by spraying grass, the slope above the backfill surface is protected by planting climbing vines, the uphill slope is temporarily protected by anchor spraying, and the uphill slope above the backfill surface is permanently protected by anchor frame grass planting to avoid rainwater erosion; the anchor frame is composed of C20 concrete and steel reinforcement skeleton, and the frame is protected by tensile mesh grass planting; in terms of structural waterproofing, embedded rubber waterstops and back-adhesive rubber waterstops are laid at the tunnel construction joints and expansion joints, and the lining structure uses C35 waterproof concrete with a seepage prevention grade of not less than P8 to form a complete tunnel waterproofing and drainage system.
[0070] Setting up a waterproof layer is an important measure to ensure the waterproof function of the tunnel. A waterproof layer is laid on the tunnel lining of all levels of surrounding rock. The waterproof layer adopts a separate waterproof board, which is composed of a waterproof board (plain board) and a non-woven fabric. The waterproof board is made of EVA waterproof board with a thickness of not less than 1.5mm. The density of the non-woven fabric (geotextile) is not less than 350g / m².
[0071] Before laying the waterproof membrane, the surface of the initial support shotcrete in the tunnel should be treated, removing hard objects such as anchor bolt heads and rebar ends. Uneven areas should be repaired with shotcrete and mortar leveling. The pit ratio D / L ≤ 1 / 6 (D: the depth of rock indentation between two adjacent convex surfaces of the initial support; L: the distance between two adjacent convex surfaces of the initial support). Leaks should be grouted first. The waterproof membrane should be made of polymer material, and joints are allowed within the specified length. The surface of the waterproof membrane should be flat, with neat edges, free from defects such as cracks, mechanical damage, creases, holes, air bubbles, and abnormal adhesions that affect its use. Unless otherwise specified, the waterproof membrane should be white in color and free from pigments and fillers. Under the condition that it does not affect its use, the surface of the waterproof membrane should be free from pits. The depth of any marks should not exceed 5% of the thickness. The waterproofing membrane is laid using a nail-free hot-melt method, where it is glued to the round pads of the plastic lining using a "hot-melt" method, thus preventing mechanical damage to the membrane. The waterproofing membrane is laid using conventional methods, in a circumferential direction, which will not be elaborated further. Note that in this embodiment, the overlap joints between waterproofing membranes should be staggered from expansion joints and construction joints by a distance of not less than 500mm. The overlap width of the waterproofing membrane is 10cm, and the welding width is not less than 12.5mm. The waterproofing membrane is fixed using adhesive hot-melt welding; the waterproofing layer should not be stretched taut between the rubber pads, ensuring close contact between the membrane surface and the shotcrete. The area where the waterproofing membrane is laid should be at least a safe distance from the excavation face required for blasting. The waterproofing layer must not be damaged during secondary lining concrete pouring. A schematic diagram of the waterproofing membrane and geotextile laying is shown below. Figure 15 As shown.
[0072] Waterstops must be installed at tunnel expansion joints, longitudinal and circumferential construction joints within the tunnel body; such as Figures 11 to 14 The image shows the waterproofing design for expansion joints and construction joints;
[0073] (1) Expansion joint
[0074] Waterproofing measures are adopted at the tunnel expansion joints using embedded rubber waterstops and back-adhesive waterstop strips.
[0075] The tunnel entrance area is generally shallower and more susceptible to natural conditions, resulting in lower stability compared to the tunnel interior. An expansion joint is installed at the boundary between the open and closed sections of the tunnel entrance and exit. To prevent secondary lining cracking and other defects caused by uneven settlement, expansion joints are installed at locations where the lining type changes. Class IV and V surrounding rock are both weak or fractured rock layers, and an expansion joint should be installed when the continuous length exceeds 50m. Expansion joints can also serve as construction joints. At the locations where expansion joints are installed, construction joints should be adjusted to the same position, with a joint width of 2cm. Embedded rubber waterstops are installed across the entire cross-section, and the joints are filled with asphalt-impregnated hemp fiber.
[0076] Installation procedure for embedded waterstop strip:
[0077] ① Drill Φ12mm steel bar holes at 1m intervals on the end plate along the axis of the lining scheme;
[0078] ② Insert the Φ10mm steel bar clip from one side of the concrete to be cast into the other side and clamp half of the waterstop strip inside. The other half of the waterstop strip is fixed to the end plate. At the same time, install asphalt wood fiber board and foam board.
[0079] ③ Pour concrete;
[0080] ④ Remove the end plate after the cast concrete has solidified;
[0081] ⑤ Straighten the waterstop near the central steel bar, then bend the Φ10mm steel bar clip onto the waterstop, and cast the next ring of concrete.
[0082] ⑥ Remove the foam board and the asbestos, asphalt, and hemp fibers that were filled in;
[0083] ⑦ Press two-component polysulfide waterproof sealant into local gaps;
[0084] (2) Construction joint
[0085] The secondary lining trolley template is 10m long, and the secondary lining length of each template is 9.9m (10cm overlap) (local adjustments are made at settlement joints and expansion joints). A circumferential embedded rubber waterstop is installed every 9.9m. A longitudinal continuous embedded rubber waterstop is installed at the construction joint between the secondary lining invert and the sidewall. The waterstops are all located at the center of the lining thickness.
[0086] Installation process of embedded rubber waterstop:
[0087] ① Drill Φ12mm holes at 1.0m intervals on the end plate along the design axis of the secondary lining;
[0088] ② Pass the Φ10mm steel bar through the side of the concrete to be poured, clamp half of the waterstop on the inside, and place the other half of the waterstop flat on the end formwork.
[0089] ③ After the secondary lining concrete is poured and solidified, remove the end formwork, straighten the waterstop near the joint, then bend the other end of the Φ10mm steel bar to fix the waterstop, and cast the next ring of secondary lining.
[0090] Specifically, such as Figure 5 As shown, the circumferential drainage pipes are Φ50mm flexible permeable pipes, generally laid evenly longitudinally along the initial support surface, with an average of one pipe every 10m. This number can be increased as needed when local water volume is high, such as increasing to one pipe every 5m in water-rich sections of Class V surrounding rock. In areas with seepage in strips after tunnel excavation, 1-3 Φ100mm semi-circular drainage pipes are laid along the rock surface as a circumferential drainage strip; Figure 7 As shown, the initial support should be shotcrete on both sides, with a thickness of ≥4cm for both layers. In addition to being laid along the rock surface, the circumferential drainage strip should also be placed at the cracks in the first layer of shotcrete. To ensure the semi-circular drainage strip adheres closely to the rock surface, as shown... Figure 8As shown, after the tunnel is excavated, a 2-5cm thick layer of concrete is sprayed first, and then a semi-circular drainage pipe is laid. For areas with particularly severe seepage in the form of strands, a Φ50mm PE single-wall non-porous corrugated pipe can be used to directly drain the water into the lateral drainage ditch.
[0091] Specifically, to ensure the accurate and reasonable installation position of the circumferential drainage pipe, the installation position of the circumferential drainage pipe is measured, laid out, and marked before installation; then, expansion anchors are driven into the positioning holes or the steel bar ends are pre-embedded in the positioning holes with anchoring agent, and fixing nails are installed on both sides of the blind pipe; finally, the blind pipe is wrapped with non-woven fabric and tied with wire; the blind pipe is clamped with clips and then fixed to the expansion bolts.
[0092] Specifically, the transverse drainage blind pipes are made of Φ100mm HDPE double-wall perforated corrugated pipes (half-perforated), installed every 10m along the longitudinal direction of the tunnel, and preferably located at the circumferential construction joints of the invert arch to drain surface water. Figure 9 , Figure 10 As shown, the transverse drainage blind pipes are installed in the trenches reserved in the backfill of the invert arch. The transverse drainage blind pipes are wrapped with non-woven geotextile. Then, the trenches are filled with washed gravel with a particle size of 2-3 cm, and the lower base layer is laid. Figure 1 , Figure 5 As shown, a Φ100mm HDPE double-wall corrugated pipe is used for the transverse drainage pipe, and one pipe is installed every 10m along the longitudinal direction of the tunnel to connect the longitudinal drainage blind pipe behind the wall with the drainage ditch on the roadside; as shown Figure 5 As shown, the longitudinal drainage pipes behind the wall use Φ100mm PE double-wall corrugated pipes with half-perforated sides. Their slope is consistent with the tunnel's longitudinal slope at 2%. The longitudinal drainage pipes behind the wall are disconnected and plugged at the intersections of each transverse tunnel and the main tunnel; for example... Figure 6 As shown, C30 concrete pipe seats are used for the longitudinal drainage pipes on both sides of the arch tunnel, and the concrete pipe seats are cast together with the invert arch; the transverse drainage blind pipes, circumferential drainage pipes, and longitudinal drainage blind pipes on the back wall are all wrapped with non-woven geotextile to prevent cement or soil from clogging the pipes and to ensure smooth drainage; as Figure 3 , Figure 4 As shown, the horizontal water guide pipe and the circumferential drainage pipe are connected to the longitudinal blind drainage pipe behind the wall using tees; as Figure 1 As shown, a sedimentation well is set up every 30m in the drainage ditch. All sedimentation wells are underground wells and also serve as inspection wells.
[0093] Specifically, such as Figure 1 , Figure 2 As shown, the drainage ditch on the left side of the driving direction is 40cm wide and 40cm deep, and the drainage ditch on the right side of the driving direction is 60cm wide and 35cm deep. The top of the drainage ditch is covered with a C30 precast reinforced concrete cover plate, and the roadside ditch is set on the C30 precast reinforced concrete cover plate.
[0094] Specifically, the tunnel entrance and exit are all downslope drainage. During tunnel construction, a drainage ditch with a width and depth of 30cm is left on one side of the constructed invert surface for temporary drainage. A temporary drainage ditch is dug on the upper step to direct the water flow to the invert excavation site on one side. A sump is set up at the invert excavation site, and a water pump is used to pump the water to the temporary drainage ditch and discharge it outside the tunnel.
[0095] This invention establishes a complete and unobstructed drainage system both inside and outside the tunnel, preventing water from seeping into the tunnel from the surrounding underground. A drainage structure for the central partition wall is constructed by installing drainage pipes and circumferential drainage strips at the top of the partition wall and directing seepage water to a culvert. Compared to traditional partition wall construction methods, this method is implemented after the partition wall construction is complete, with the circumferential drainage strips installed along the outer side of the partition wall, without altering the concrete structure or load-bearing capacity of the partition wall. The installation of separate waterproofing membranes in the tunnel lining effectively prevents moisture from penetrating into the lining structure. The installation of waterstops at key locations in the tunnel effectively prevents moisture from seeping into the tunnel through these gaps. The construction of various drainage pipes effectively collects and discharges accumulated water inside the tunnel, thereby reducing the accumulation of seepage water. This method achieves comprehensive prevention and control of seepage water in straight, thin-walled, multi-arch tunnels, ensuring the safety of the tunnel structure while mitigating potential damage caused by seepage water, improving the reliability and service life of the tunnel. These measures work together to effectively reduce the risk of seepage water and ensure the long-term stability of the tunnel.
[0096] It is understood that the above description is merely exemplary and the embodiments of this application are not intended to limit the scope of the invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.
Claims
1. A method for preventing water leakage in the lining of a thin-walled, arched tunnel, characterized in that: Constructing a complete and unobstructed drainage system inside and outside the cave includes the following steps: Step 1: Waterproofing construction at the tunnel entrance: Before excavation of the slope at the tunnel entrance, according to the terrain, intercepting ditches are laid out along the terrain 5m away from the tunnel entrance, the side of the open tunnel, and the slope brush line. The surface runoff is directed to the natural valley or temporary drainage system through the drainage ditch. The intercepting ditches are rectangular in shape and are poured with C20 concrete. To prevent uneven settlement of the tunnel roof from damaging the intercepting ditches, a settlement joint with a width of 2cm is set every 10m of the intercepting ditches, and the settlement joint is filled with asphalt hemp rope. On both sides of the tunnel driving lane, roadside ditches and drainage ditches are constructed. The drainage ditches on both sides are connected by transverse drainage blind pipes, which are double-walled half-perforated corrugated pipes. Step 2: After the central tunnel is constructed, the central partition wall is constructed. The cavity at the top of the central partition wall is backfilled with mortar-grouted rubble to form an arched top. A central wall drainage pipe is installed longitudinally at the shoulder of the central partition wall top. The central wall drainage pipe is a double-wall perforated corrugated pipe. Longitudinal drainage pipes are installed at the corners on both sides of the tunnel carriageway. The longitudinal drainage pipes on the back of the wall are double-wall half-perforated corrugated pipes. In areas with seepage after tunnel excavation, a circumferential drainage strip is laid along the rock surface. The circumferential drainage strip is a semi-circular drainage pipe. The end of the circumferential drainage strip closest to the central partition wall is connected to the central wall drainage pipe. The end of the circumferential drainage strip away from the central partition wall is led to the drainage ditch through a transverse water guide pipe. The transverse water guide pipe is a double-wall corrugated pipe. Step 3 includes waterproofing and drainage construction for both the culvert and the open section of the tunnel. Tunnel culvert waterproofing and drainage construction: A waterproof layer is laid between the initial support and the secondary lining as the first waterproofing measure; the secondary lining of the arch and sidewalls uses waterproof concrete of not less than P8 as the second waterproofing measure; circumferential drainage pipes are installed at intervals on the surface of the initial support, and the circumferential drainage pipes are flexible permeable pipes; the drainage pipes in the middle wall are connected to the circumferential drainage pipes, and the two ends of the circumferential drainage pipes are connected to the longitudinal drainage pipes on the back wall of the tunnel on both sides respectively, and then the water is introduced into the drainage ditch and discharged outside the tunnel through the transverse water guide pipe; Waterproofing and drainage construction of the open-cut section of the tunnel: In the open-cut section, the outer layer of the open-cut lining is constructed with a two-layer waterproof fabric and a one-layer membrane waterproof layer, and a 2cm thick cement mortar protective layer. The backfill soil and rock bottom layer uses backfill drainage pipes to remove seepage and accumulated water. The backfill drainage pipes are Φ100mm HDPE corrugated pipes; the two-layer waterproof fabric and one-layer membrane waterproof layer has a strength of 350g / m². 2 Geotextile + 1.5mm thick EVA waterproof membrane + 350g / m 2 Geotextile structure; a clay waterproofing layer is installed on the backfill surface of the open tunnel to prevent surface runoff from seeping down. The surface of the clay waterproofing layer has a slope, and drainage ditches are set at the low-lying areas at both ends of the clay waterproofing layer. Surface runoff flows into the drainage ditches under the action of the clay waterproofing layer and is discharged away. In terms of structural waterproofing, embedded rubber waterstops and back-adhesive rubber waterstops are laid at the construction joints and expansion joints of the open tunnel. At the same time, the structure uses waterproof concrete with a seepage prevention grade of not less than P8 to form a complete waterproofing and drainage system for the open tunnel.
2. The method for preventing water leakage in the lining of a thin-walled, arched tunnel according to claim 1, characterized in that: The lining concrete is produced by an automatic concrete metering and mixing plant, transported by concrete mixer trucks, and poured by concrete pumps. The lining is constructed using a full-section hydraulic lining trolley. The invert arch of the entire tunnel is constructed in advance, and the lining follows closely behind. The secondary lining arch, invert arch, and outer sidewalls are constructed with 60cm thick reinforced concrete in Class V surrounding rock sections and 50cm thick reinforced concrete in Class IV surrounding rock sections. The inner sidewalls are all constructed with 50cm thick reinforced concrete. The central partition wall is constructed with 150cm thick reinforced concrete.
3. The method for preventing water leakage in the lining of a thin-walled, arched tunnel according to claim 1, characterized in that: The waterproof layer consists of a 1.5mm thick EVA waterproof membrane and 350g / m³ waterproofing material. 2 Non-woven fabric; embedded rubber waterstops and grouting pipe expansion waterstops are installed at the construction joints of the secondary lining for water sealing, and back-adhesive rubber waterstops and embedded rubber waterstops are installed at the expansion joints for water sealing.
4. The method for preventing water leakage in the lining of a thin-walled, arched tunnel according to claim 1, characterized in that: The tunnel lining uses C35 reinforced concrete with a permeability grade of not less than P8. After the tunnel lining construction is completed, a 3cm thick M10 cement mortar leveling layer is poured on the outer surface of the lining. A two-layer waterproof layer and a cement mortar protective layer are then laid on the leveling layer, followed by backfilling with grouted rubble masonry and crushed stone. The grouted rubble masonry is backfilled on both sides first, followed by crushed stone backfilling, proceeding from bottom to top in symmetrical layers according to the design. The backfill soil should be compacted in layers. The height difference between the backfill surfaces on both sides should not exceed 0.5m. The thickness of each layer for manual compaction should not exceed 0.25m, and the thickness of each layer for mechanical compaction should not exceed 0.3m. After the tunnel backfilling is completed, timely greening and protection work should be carried out at the tunnel entrance and the tunnel top. The backfill of the tunnel top is protected by spraying grass, and the slope above the backfill surface is protected by planting climbing vines. The slope above the backfill surface is temporarily protected by anchor spraying, and the slope above the backfill surface is permanently protected by anchor frame planting grass to prevent rainwater erosion.
5. The method for preventing water leakage in the lining of a thin-walled, arched tunnel according to claim 1, characterized in that: The circumferential drainage pipes are made of Φ50mm flexible permeable pipes. Under normal circumstances, they are laid evenly along the initial support surface, with one pipe every 10m on average. In water-rich sections of Class V surrounding rock, the spacing is increased to one pipe every 5m. In areas with seepage in strands after tunnel excavation, 1 to 3 Φ100mm circumferential drainage strips are laid along the rock surface. To ensure that the semi-circular drainage pipes are in close contact with the rock surface, 2 to 5cm thick concrete is sprayed before laying the semi-circular drainage pipes after tunnel excavation. In areas with particularly severe seepage in strands, Φ50mm PE single-wall non-porous corrugated pipes are used to directly drain the water into the lateral drainage ditch.
6. The method for preventing water leakage in the lining of a thin-walled, arched tunnel according to claim 1, characterized in that: The drainage ditch on the left side of the driving direction is 40cm wide and 40cm deep, while the drainage ditch on the right side of the driving direction is 60cm wide and 35cm deep. The top of the drainage ditch is covered with a C30 precast reinforced concrete cover plate, and the roadside ditch is set on the C30 precast reinforced concrete cover plate. The transverse drainage blind pipe is Φ100mm and is set at 10m intervals along the longitudinal direction of the tunnel, and is set at the circumferential construction joint of the invert arch as much as possible to drain the water on the road surface. The transverse drainage blind pipe, circumferential drainage pipe and longitudinal drainage blind pipe behind the wall are all wrapped with non-woven geotextile to prevent cement or soil from clogging the pipes and ensure smooth drainage.
7. The method for preventing water leakage in the lining of a thin-walled, arched tunnel according to claim 1, characterized in that: The longitudinal drainage pipe behind the wall is Φ100mm and is installed along the bottom of the tunnel. Its slope is consistent with the longitudinal slope of the tunnel. The longitudinal drainage pipe behind the wall is disconnected and plugged at the intersection of each transverse tunnel and the main tunnel. The transverse water guide pipe and the circumferential drainage pipe are connected to the longitudinal drainage blind pipe behind the wall by tees.
8. The method for preventing water leakage in the lining of a thin-walled, arched tunnel according to claim 1, characterized in that: A sedimentation well is installed every 30m in the drainage ditch. All sedimentation wells are underground and also serve as inspection wells.