A complex geological disaster complex disposal method

Abstract

The application discloses a complex geological disaster complex treatment construction method, and belongs to the technical field of tunnel construction, and comprises the following steps: carrying out spoil backfilling and lifting for an existing gully; carrying out reverse pressure support on an unstable slope body of a tunnel portal, and guiding and changing a debris flow; carrying out pre-reinforcement on a side and upward slope of the tunnel; and carrying out tunnel portal construction by adopting a right-angle portal-entering mode or an oblique portal-entering mode. The construction method can effectively solve the construction problem of a typical 'two-tunnel-enclosing-one-bridge' complex geological disaster complex, and can guarantee the stability of the side slope of the tunnel portal during the whole construction process, so that the construction safety, stability, integrity and efficiency are achieved.

Description

Technical Field

[0001] This invention belongs to the field of tunnel construction technology, specifically relating to a method for dealing with complex geological disaster complexes. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] The mountainous terrain is steep and high, with deep valleys and frequent fault activity. The extremely complex geological conditions and fragile ecological environment create extremely complex engineering construction conditions. Natural disasters such as landslides, collapses, and debris flows are prevalent along the route, and waste disposal sites, high fills, and deep road cuts are widely distributed. There are also multiple geological hazards coexisting, which poses huge safety risks, construction costs, and schedule pressures to the project.

[0004] In recent years, following the principle of geological route selection, the design in deep valley areas is often a typical combination of two tunnels and one bridge. In particular, the construction of highway and railway tunnels has brought many technical challenges and problems. The handling of complex geological disaster complexes with typical two tunnels and one bridge, ensuring construction safety and improving project quality are the core technical challenges.

[0005] In recent years, the treatment of complex geological hazard complexes has gradually emerged due to urgent transportation needs, bringing greater challenges to highway and railway construction. Currently, there is a lack of in-depth analysis and research on the design and construction of typical "two tunnels sandwiching a bridge" complex geological hazard complexes, failing to provide scientific and efficient technical guidance for safe construction and quality assurance. Furthermore, existing tunnel treatment methods cannot meet the needs of complex geological hazard complexes and cannot provide any relevant experience for reference. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a construction method for dealing with complex geological disaster complexes. This method can effectively solve the construction difficulties of dealing with typical complex geological disaster complexes such as "two tunnels sandwiching a bridge". The entire construction process can ensure the stability of the tunnel entrance slope, achieving safe, stable, holistic, and efficient construction results.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] In a first aspect, the present invention provides a method for dealing with complex geological disaster complexes, comprising the following steps:

[0009] The existing gullies were raised by backfilling with waste material.

[0010] Counter-pressure support is used to divert and divert debris flows from the unstable slope at the tunnel entrance.

[0011] Pre-reinforcement of the tunnel side slope;

[0012] Tunnel construction can be carried out using either orthogonal or oblique entry methods.

[0013] As a further technical solution, before backfilling the gully with waste, a water-blocking dam is set up upstream of the gully, and a culvert is laid at the bottom of the gully so that the upstream water flows through the backfill area in the form of a culvert during construction.

[0014] As a further technical solution, multiple blind riprap trenches are laid at the bottom of the gully to drain water from the waste.

[0015] As a further technical solution, the process of counter-pressure support is as follows: a retaining wall or sand dam is set at the downstream lock position of the gully crossed by the tunnel route to reinforce the slope toe of the counter-pressure spoil body.

[0016] As a further technical solution, after reinforcing the slope toe, the waste is backfilled and compacted layer by layer from the location of the retaining wall or silt dam upwards, and a leveling area is formed between the two tunnels, which serves as a construction platform and site.

[0017] As a further technical solution, the process of diverting debris flow is as follows: calculate the size of the diversion channel based on the catchment area, and after the counterweight body is constructed to the design elevation and the compaction degree meets the requirements, construct a concrete diversion channel on the waste debris through reverse excavation along the original debris flow path, connecting with the upstream and downstream gullies; at the location where the diversion channel crosses the highway route, a pile-foundation frame bridge is used to span the diversion channel.

[0018] As a further technical solution, when adopting orthogonal tunnel entry, the process of pre-reinforcing the tunnel side slope is as follows: extend the length of the open tunnel, and set anti-slide piles and pile foundation retaining walls on the outside of the open tunnel lining. The retaining walls are all constructed on the counter-pressure spoil backfilling platform.

[0019] As a further technical solution, when using oblique entry into the tunnel, the process of pre-reinforcing the slope of the tunnel side is as follows: adopting graded unloading to reduce the sliding force of the landslide body; and using a support method that combines anchor bolts or anchor cable grid beams with graded anti-slide piles to support the deep colluvial body.

[0020] As a further technical solution, the construction process of orthogonal tunneling is as follows:

[0021] First, backfill to the inner contour of the tunnel excavation area, then construct the arch support. After the arch support strength reaches the design requirements, carry out the upper backfill construction. After the tunnel slope is stabilized by counter-pressure backfill, carry out the construction of double-row 180° advanced pipe shed, and reinforce the pipe shed with grouting. After the advanced pipe shed construction is completed, the tunnel culvert construction is carried out. Mechanical excavation is used for soil surrounding rock tunnels.

[0022] As a further technical solution, the construction process of the oblique tunnel entrance is as follows:

[0023] The open-cut tunnel is excavated in layers and stages, with support provided during excavation; advanced large pipe roofs and arch supports are constructed; after entering the tunnel, the soil strata at the tunnel entrance should be excavated mechanically; lining and backfilling of the open-cut tunnel are carried out.

[0024] The beneficial effects of the present invention are as follows:

[0025] The treatment method of this invention adopts the following construction procedures: raising the slag dumping area, counter-pressure support for the unstable slope at the tunnel entrance, orderly diverting debris flow, pre-reinforcing the tunnel side slope, zero-excavation tunnel entry, and segmented staggered construction. The entire construction process can ensure the stability of the tunnel entrance slope and achieve the effects of safe, stable, integrated, and efficient construction.

[0026] The disposal method of this invention utilizes tunnel spoil to backfill and counter-pressure the gully, which not only digests a large amount of spoil and reduces the cost of transporting spoil over long distances, thus reducing project costs, but also provides counter-pressure to the unstable slopes on both sides, improving the risk resistance of the "two tunnels sandwiching a bridge" project. At the same time, the spoil backfill area serves as a construction platform and site, reducing the use of temporary construction land and providing greater convenience for construction.

[0027] The disposal method of the present invention involves backfilling and raising the existing gully with waste, setting up a diversion channel according to the debris flow path calculation, and using a pile-foundation frame bridge to span the diversion channel. This ensures that the open water or debris flow in the gully can pass smoothly through the waste body, and ensures the stability of the waste body, avoiding the formation of new debris flow sources.

[0028] The treatment method of this invention pre-reinforces the unstable slope of the tunnel entrance, adopting a scheme of reinforcing before entering the tunnel, which minimizes the geological disasters on the slope caused by the excavation of the tunnel entrance. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, 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 improper limitation of the invention.

[0030] Figure 1 This is a flowchart of a complex geological disaster treatment method according to one or more embodiments of the present invention;

[0031] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only. Detailed Implementation

[0032] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0033] In a typical embodiment of the present invention, such as Figure 1 As shown, a construction method for dealing with complex geological disaster complexes is proposed. Based on the comprehensive consideration of tunnel entry method, safety and stability analysis of tunnel entrance slope, reinforcement and protection, compaction of high fill roadbed, stability analysis and treatment of spoil heap, and debris flow diversion, the method proposes the following construction procedures: raising spoil heap in gullies, counter-pressure support for unstable slopes at tunnel entrance, orderly diversion of debris flow, pre-reinforcement of tunnel side slopes, zero-excavation entry, and phased staggered construction.

[0034] The treatment method specifically includes the following steps:

[0035] Step 1: Comprehensive and effective utilization of tunnel spoil;

[0036] By adopting a partial bridge-to-roadbed conversion at the tunnel entrance, waste disposal is utilized, the stability of the tunnel entrance slope is increased, and a construction platform and site are formed, achieving safe, stable, integrated, and efficient construction results.

[0037] Step 2: Crossing the mudslide;

[0038] The existing gullies are backfilled with waste and raised. Diversion channels are set up according to the debris flow calculation and diverted. A pile-foundation frame bridge is used to span the diversion channels. The scheme is designed according to the actual engineering characteristics, which effectively utilizes the waste, reduces the harm of debris flow to the project, and has significant economic benefits.

[0039] Step 3: Slope protection at the tunnel entrance;

[0040] The unstable slope at the tunnel entrance was pre-reinforced, adhering to the principle of reinforcing before entering the tunnel, thus minimizing geological hazards on the slope caused by tunnel entrance excavation.

[0041] Step 4: Entering the tunnel;

[0042] Tunnel construction can be carried out using either orthogonal or oblique entry methods.

[0043] In step 1, the utilization of tunnel spoil includes:

[0044] To improve the stability of the slopes at the tunnel entrances on both sides and to prevent deep slippage of the slopes due to construction disturbances, heavy rainfall, earthquakes, etc., the gully between the two tunnels is backfilled with tunnel spoil for counter-pressure.

[0045] Step 1 also includes the utilization of tunnel spoil:

[0046] Set up a slag retaining wall or sand retaining dam at the narrowest point downstream of the gully that the tunnel route crosses to reinforce the slope toe of the back pressure spoil body.

[0047] The reinforcement and counter-pressure of the waste slag specifically includes the following processes:

[0048] Starting from the location of the retaining wall or silt dam, the waste material is backfilled and compacted layer by layer upwards, forming a large fill area between the two tunnels. The compaction degree of the backfill waste material needs to reach more than 90% to reduce the risk of traction damage to the bridge-to-road section that may be caused by the settlement of the waste material in the later stage.

[0049] The waste from the section of the tunnel where the bridge was converted to a road was sorted and broken down into smaller pieces and used as roadbed fill material. It was then backfilled to the roadbed elevation, and measures such as dynamic compaction and impact rolling were used within a certain lateral width of the roadbed to ensure that the roadbed compaction met the design requirements.

[0050] In this process, the use of tunnel spoil to backfill and counter-pressure the gully not only consumes a large amount of spoil and reduces the cost of transporting spoil over long distances, thus reducing project costs, but also provides counter-pressure to the unstable slopes on both sides, improving the risk resistance of the "two tunnels and one bridge" project. At the same time, the filled area serves as a construction platform and site, reducing the use of temporary construction land and providing greater convenience for construction.

[0051] In this case, backfilling the scour ditch with waste rock will inevitably block the original drainage channel or the upstream debris flow channel, and the waste rock will also become a new source of debris flow. How to enable the upstream debris flow to quickly cross the waste rock and ensure the stability of the drainage channel is crucial to the long-term stability of the project. Therefore, in step 2, the debris flow is diverted.

[0052] First, before backfilling the gully with waste, a water-retaining dam is set up at a suitable location upstream of the gully, and a culvert of appropriate diameter is laid at the bottom of the gully to ensure that upstream water flows through the backfill area via the culvert during construction. Simultaneously, to ensure the overall stability of the backfill body and reduce the impact of water on the waste, multiple blind drains made of rubble are laid at the bottom of the gully according to the actual situation to quickly drain water from inside the waste.

[0053] Debris flow diversion includes the following processes:

[0054] Calculate the appropriate diversion channel dimensions based on the catchment area. After the counterweight body is constructed to the design elevation and the compaction degree meets the requirements, construct a concrete diversion channel on the spoil heap using reverse excavation along the original debris flow path, connecting with the upstream and downstream gullies. The longitudinal slope of the diversion channel should be reasonably designed to allow the debris flow to pass through the counterweight body quickly. Where the diversion channel crosses the highway route, a pile-foundation frame bridge will be used to span the diversion channel, minimizing the impact of the debris flow on the road construction.

[0055] The above-mentioned measures of diversion channel + pile foundation frame bridge + rubble blind ditch can ensure that the open water or debris flow in the gully can pass smoothly through the waste body, and ensure the stability of the waste body, avoiding the formation of new debris flow sources.

[0056] In step 3, the support measures for the slope at the entrance of the tunnel should be comprehensively considered based on the properties of the rock and soil on both sides of the mountain and the slope morphology.

[0057] For tunnels with orthogonal entrances and large, high slopes containing colluvial deposits, reinforcing these slopes using engineering measures is not only a massive undertaking but also inevitably involves disturbance during the reinforcement process, potentially leading to significant landslides. Therefore, a pre-reinforcement approach at the tunnel entrance can be adopted to minimize disturbance to the slopes during construction. Specific measures include: appropriately extending the length of the open-cut tunnel and installing anti-slide piles and pile-foundation retaining walls on the outside of the open-cut lining. These serve both as anti-slide measures for the slopes and as support structures on both sides of the open-cut tunnel. To further reduce disturbance to the slopes, the retaining walls are constructed on a counter-pressure spoil backfill platform. After the open-cut tunnel construction and backfilling are completed, the tunnel at the colluvial deposit is excavated using a cut-and-cover method.

[0058] For deep colluvial tunnels with oblique entry points and adequate support conditions, a combination of extended open-cut tunnel and side slope support can be adopted. Specifically, this involves: implementing staged unloading to reduce the sliding force of the landslide; and using a support method combining anchor (cable) grid beams and staged anti-slide piles to support the deep colluvial body. Simultaneously, to minimize disturbance to the colluvial body during tunnel entry, the method of constructing the open-cut tunnel first and then the tunnel itself can also be adopted.

[0059] In step 4, when using orthogonal tunnel entry, since there is a ditch below the tunnel entrance, in order to ensure the stability of the tunnel entrance and the slope, the tunnel entry scheme follows the principle of "zero excavation" and adopts a support scheme for tunnel entry.

[0060] Specifically, the construction process for the orthogonal tunnel entrance is as follows:

[0061] (1) To avoid excavation at the tunnel entrance, a river ditch frame bridge was first constructed, and the bridge ends were backfilled to near the design elevation to provide a construction platform for the tunnel entrance.

[0062] (2) On the right side of the right line of the tunnel and at the end of the open tunnel, anti-slide piles and anti-slide retaining walls are constructed. A passive protection net is constructed above the tunnel. Then, bagged sand is backfilled inside the anti-slide piles and anti-slide retaining walls. The tunnel slope is backfilled with counter-pressure to artificially create a "hidden" tunnel position.

[0063] (3) Strengthen monitoring and measurement during construction. First, backfill to the inner contour of the tunnel excavation, then construct the arch support. After the arch support strength reaches the design requirements, carry out the upper backfill construction. After the tunnel slope is stabilized by counter-pressure backfill, carry out the double-row 180° range advanced pipe shed construction and grout reinforcement of the pipe shed.

[0064] (4) After the construction of the advanced large pipe shed is completed, the tunnel construction will be carried out. For soil surrounding rock tunnels, mechanical excavation will be used. For rock surrounding rock blasting, the vibration rate should be controlled and the blasting vibration velocity should be ≤2cm / s.

[0065] During construction, in order to prevent gravel from falling into the roadbed and extend the tunnel opening, a pile foundation opening was adopted to ensure the stability of the tunnel portal; in order to prevent excessive settlement of the backfill soil between the pile foundation opening and the tunnel, grouting reinforcement with steel pipes was used.

[0066] Meanwhile, during the construction process, we will strengthen the monitoring of structures and the monitoring of surface and deep displacement.

[0067] In step 4, when using an oblique entry tunnel, the construction process is as follows:

[0068] (1) After unloading the earthwork of the upper slope, backfill the river ditch, and then implement anti-slide piles at the tunnel entrance (to the foot of the slope) and anti-slide piles on the unloading platform. Tunnel entry and slope protection can be carried out simultaneously. Tunnel entrance construction should be avoided during the rainy season as much as possible, and drainage work should be done well.

[0069] (2) Open-cut tunnels should be excavated in layers and at different stages, with support provided while excavating;

[0070] (3) Construct advanced large pipe sheds and arch supports;

[0071] (4) After entering the tunnel, the soil strata at the tunnel entrance should be excavated mechanically to control the excavation progress; the rock strata should be blasted with controlled blasting and the blasting vibration velocity ≤2cm / s.

[0072] (5) Lining and backfilling of open tunnels should be carried out in a timely manner.

[0073] During construction, strengthen the monitoring of structural and surface displacement, as well as deep displacement.

[0074] This construction method provides excellent guidance for the construction of complex geological disaster complexes, especially for typical mountain highway construction sites with two tunnels and one bridge. It is applicable or combined with other common debris flow diversion, crossing, spoil disposal, tunnel entrance methods, and side slope support. The technology has a wide range of applications, saves construction time, and ensures rapid and safe construction.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for dealing with complex geological disaster complexes, characterized in that, Includes the following steps: The existing gullies are raised by backfilling with waste. Before backfilling the gullies with waste, a water-blocking dam is set up upstream of the gullies. A culvert is laid at the bottom of the gullies so that the upstream water flows through the backfill area in the form of a culvert during construction. Multiple blind ditches made of rubble are laid at the bottom of the gullies to drain the water inside the waste. The unstable slope at the tunnel entrance is supported by counter-pressure to divert debris flow. The size of the diversion channel is calculated based on the catchment area. After the counter-pressure body is constructed to the design elevation and the compaction degree meets the requirements, a concrete diversion channel is constructed on the spoil through reverse excavation along the original debris flow path, connecting with the upstream and downstream gullies. Where the diversion channel passes under the highway route, a pile-foundation frame bridge is used to span the diversion channel. Pre-reinforcement of the tunnel side slope; Tunnel construction can be carried out using either orthogonal or oblique entry methods. The process of counter-pressure support is as follows: a retaining wall or sand dam is set at the downstream lock position of the gully crossed by the tunnel route to reinforce the slope toe of the counter-pressure spoil body; After reinforcing the slope toe, backfill and compact the waste layer by layer from the location of the retaining wall or silt dam upwards, and form a fill area between the two tunnels. The fill area serves as a construction platform and site.

2. The method for handling complex geological disaster complexes as described in claim 1, characterized in that, When using orthogonal tunnel entry, the process of pre-reinforcing the tunnel side slope is as follows: extend the length of the open tunnel, and set anti-slide piles and pile foundation retaining walls on the outside of the open tunnel lining. The retaining walls are all constructed on the backfill platform for counter-pressure spoil disposal.

3. The method for handling complex geological disaster complexes as described in claim 1, characterized in that, When using an oblique entry tunnel, the pre-reinforcement process of the tunnel side slope is as follows: staged unloading is adopted to reduce the sliding force of the landslide body; the deep colluvial body is supported by a combination of anchor bolts or anchor cable grid beams and staged anti-slide piles.

4. The method for handling complex geological disaster complexes as described in claim 1, characterized in that it is orthogonal... The construction process for entering the tunnel is as follows: First, backfill to the inner contour of the tunnel excavation area, then construct the arch support. After the arch support strength reaches the design requirements, carry out the upper backfill construction. After the tunnel slope is stabilized by counter-pressure backfill, carry out the construction of double-row 180° advanced pipe shed, and reinforce the pipe shed with grouting. After the advanced pipe shed construction is completed, the tunnel culvert construction is carried out. Mechanical excavation is used for soil surrounding rock tunnels.

5. The method for handling complex geological disaster complexes as described in claim 1, characterized in that, The construction process for the oblique tunnel entrance is as follows: The open-cut tunnel is excavated in layers and stages, with support provided during excavation; advanced large pipe sheds and arch supports are constructed; after entering the tunnel, the soil strata at the tunnel entrance should be excavated mechanically; lining and backfilling of the open-cut tunnel are carried out.

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