A dammed lake breaching process regulation method

Abstract

The application provides a dammed lake breaching process regulation method, comprising the following steps: building a diversion tunnel at a position where a dam is expected to be formed, and making the diversion tunnel inlet located in the dammed lake upstream of the dam and the diversion tunnel outlet located downstream of the dam; setting a working gate with controllable opening degree on the diversion tunnel; after the dam is formed, controlling the opening degree of the working gate to regulate the dam overtopping discharge and the overtopping flow head, ensuring low overtopping flow head and low flow speed to scour the dam slope surface, so as to realize safe dam discharge, gradual collapse of the dam accumulation body, artificial regulation of the dammed lake breaching development process and reduction of the dammed lake breaching flood peak. The application can solve the problems of dam collapse instantaneous breaching, uncontrolled breaching process and excessive breaching flood peak caused by uncontrollable dam breaching process.

Description

Technical Field

[0001] This invention relates to the field of landslide damming lake management technology in high mountain and canyon areas, and particularly to a method for regulating the process of landslide damming lake breach. Background Technology

[0002] A landslide-dammed lake is a natural lake formed in high mountain and canyon areas by sudden geological disasters such as landslides, collapses, or debris flows blocking river channels and impounding water. The solid deposits blocking the river channel are called landslide dams. Landslide dams obstruct the normal flow of water in rivers, which can easily cause the river level to rise rapidly, or even overflow and breach, resulting in abnormal outburst floods that seriously threaten the safety of life, property, and infrastructure, causing social panic or crisis.

[0003] High-risk landslide dammed lakes generally have a capacity of hundreds of millions of cubic meters, reaching the scale of large reservoirs. Especially in the upper reaches of major rivers and canyons in high mountains, the water storage capacity of landslide dammed lakes is extremely strong, and the backwater length can even reach tens of kilometers. Moreover, landslide dams are generally formed by the natural accumulation of loose sand and gravel without any artificial compaction. Once the water level rises and overflows the top, the loose accumulation is easily carried and pushed by the overflowing water flow, causing the landslide dam to overflow and collapse. In particular, for landslide dams with a high proportion of fine sand and gravel, the overflowing water flow can easily drag and carry away the fine sand and gravel, causing the landslide dam to collapse instantly and the floodwater to "pour down", forming an abnormal flood peak.

[0004] Landslide dams are typically located in remote areas with extremely harsh environments, difficult access to water and land transportation, and a severe lack of hydrogeological data. The large water storage capacity of major rivers results in a very limited window of opportunity for emergency response to landslide dams, sometimes as short as 3-5 days. Therefore, once a major or high-risk landslide dam occurs, it is extremely difficult for personnel and heavy machinery to quickly enter the site, making emergency response to landslide dams extremely challenging.

[0005] In areas prone to landslide-dammed lakes in high mountains and canyons, emergency management departments currently lack effective means to prevent such incidents. They can only conduct continuous safety monitoring of the loose mountain slopes on both banks. However, the fall of rocks from these loose slopes into the river can happen in an instant, and the volume of debris is often enormous, typically reaching hundreds of millions of cubic meters. Manually clearing this debris to restore river flow is virtually impossible. To restore river connectivity and clear the obstructing debris, emergency management departments can only wait for the lake to form before implementing emergency response engineering measures. The most effective and widely used engineering measure is the landslide dam diversion channel excavation technique. This involves manually excavating a discharge channel along the direction of water flow at the top of the dam, taking into account the material structure and slope morphology of the debris. The overflowing water scours the sand and gravel on the dam surface, causing it to collapse and allowing the stored floodwater to flow smoothly downstream, restoring connectivity between the upstream and downstream sections of the river. However, in the early stages of the landslide dam failure, the inflow into the reservoir was far higher than the outflow from the dam's overflow. The reservoir level continued to rise, and the overflow head continued to increase. Some high-risk landslide dams were composed mainly of fine-grained sand and gravel, storing hundreds of millions of cubic meters of floodwater. The overflow head reached 3-8 meters, and the flow velocity even reached 10 m / s. Under the continuous scouring effect of the high water head and high velocity overflow, the sand and gravel on the dam slope were easily carried away and sheared, leading to the instantaneous collapse and loss of control of the landslide dam failure process.

[0006] Due to the extreme danger and complexity of the landslide dam breach development process, the engineering community is currently largely helpless and can only let it develop unchecked. Some experts have proposed manually throwing tetrahedrons during the breach to slow down the erosion of the dam by the breaching water flow. However, the harsh environment and difficult access at the landslide dam site mean that personnel and machinery must be evacuated in advance once the dam overflows and breaches, making manual tetrahedron throwing virtually impossible. Other experts have proposed laying wall-mounted gabion strings and slope-attached protective nets on both sides of the diversion channel and the upstream slope of the dam to slow down the lateral erosion and longitudinal cutting of the dam by the overflowing water flow, thereby delaying the dam's collapse. However, the structure and timing of the wall-mounted gabion strings and slope-attached protective nets are extremely difficult to control. If they are introduced into the diversion channel too early, they could easily obstruct the normal discharge of the overflowing water flow, thus triggering a backlash. Therefore, the above technical solutions are currently still in the laboratory research and development stage.

[0007] Therefore, a method for regulating the landslide dam breach process needs to be proposed to control the breach process and avoid problems such as instantaneous collapse of the landslide dam, uncontrolled breach process, and excessively large breach flood peak. Summary of the Invention

[0008] The purpose of this invention is to provide a method for controlling the breaching process of a landslide dam, in order to solve the problems of uncontrollable landslide dam breaching processes, such as instantaneous collapse, uncontrolled breaching process, and excessively large breaching flood peaks.

[0009] To solve the above-mentioned technical problems, the present invention provides a method for regulating the process of landslide dam failure, comprising: Construct a diversion tunnel at the location where a landslide dam is expected to form, with the tunnel inlet located in the landslide lake upstream of the dam and the tunnel outlet located downstream of the dam. A controllable opening working gate is installed on the diversion tunnel; Once the landslide dam is formed, the opening of the working gate is controlled to regulate the outflow and head of the overburden, ensuring that the overburden has a low head and low velocity to scour the slope of the landslide dam, thereby achieving the safe release of floodwater and the gradual collapse and breach of the landslide dam's accumulation.

[0010] Optionally, before constructing the diversion tunnel, statistically analyze the historical scale of the landslide dam, conduct a preliminary assessment of the future size and location of the landslide dam, and predict the maximum backwater level H of the landslide dam. max , return water length L, inflow rate Q0.

[0011] Optionally, the site selection requirements for the diversion tunnel are as follows: the distance L1 from the inlet of the diversion tunnel to the upstream slope of the estimated landslide dam should be in the range of 0 to 1 / 2L, and the distance L2 from the outlet of the diversion tunnel to the downstream toe of the estimated landslide dam should be controlled at around 200-500m.

[0012] Optionally, the diversion tunnel includes an inlet section, a control section, a tunnel body section, and a flood discharge and energy dissipation section. The inlet section and the control section are kept horizontal, and the elevation of the bottom plate of the inlet section and the control section is H2, which is higher than the riverbed siltation elevation. The longitudinal slope i of the tunnel body section is controlled at approximately 0.05 to 0.1. The maximum discharge capacity of the diversion tunnel is Q. S The maximum discharge capacity Q of the diversion tunnel is required. S The inflow rate reached 2 to 5 times that of the landslide dammed lake, Q0.

[0013] Optionally, a working gate is arranged in the control section, and an intake tower and a gate opening and closing machine room are arranged on the top of the control section. The opening degree e of the working gate is controlled through the gate opening and closing machine room and the intake tower.

[0014] Optionally, the platform elevation H1 of the hoist room is higher than the maximum backwater level H of the landslide dam. max 5-10m.

[0015] Optionally, after the landslide dam forms, the opening of the working gates is controlled to regulate the outflow and head of the floodwaters flowing over the dam, thereby achieving safe flood discharge and gradual collapse of the landslide dam's accumulation body. When a landslide dam blocks a river channel and the reservoir water level remains high, the working gates are closed. When the water level of the landslide dammed lake gradually rises to the top of the dam, the working gate is opened, the opening degree e of the working gate is increased and adjusted, and the discharge flow Q1 from the diversion tunnel is controlled between 0 and A and the inflow flow Q0. Wait until the water level of the landslide-dammed lake rises to the top H of the landslide dam. t1 At the same time, continuously increase the opening degree e of the working gate to control the discharge flow Q1 of the diversion tunnel to be within the inflow flow Q0 of A to B; Wait until the water level of the landslide-dammed lake rises to the top H of the landslide dam. t1 ~H t2 At the same time, the opening degree e of the working gate is continuously increased and adjusted to control the discharge flow Q1 of the diversion tunnel to be B to C times the inflow flow Q0. Where 0 < A < B < C ≤ 1, 0 < H t1 ≤0.2<H t2 ≤0.5m.

[0016] Optional, also includes: Continuously monitor the development of the landslide dam breach and the water depth at the breach opening. Based on the water depth at the breach opening and the location of the headwaters slope, adjust the opening degree e of the diversion tunnel gate to ensure that the maximum water depth at the breach opening is controlled within H. t2 Within the affected area and along the source slope, the water depth at the crest of the landslide dam is controlled on the downstream slope. If the landslide dam breaches, the water depth will exceed the specified height (H). t2 Alternatively, by tracing the steep slope back to the breach of the landslide dam, the opening degree e of the working gate of the diversion tunnel can be increased.

[0017] Optional, also includes: When the downstream steep slope of the landslide dam develops back to the breach of the landslide dam, the opening of the working gate is continuously increased by e, and the discharge flow of the diversion tunnel is controlled to be D to E times the inflow flow Q0, so as to quickly reduce the water level of the landslide lake and reservoir and the head of the flooded water flow at the breach of the landslide dam, reduce the flow velocity of the overburden flow, and slow down the scouring of the landslide dam by the overburden flow. Once the water level of the landslide-dammed lake has dropped to the level of the breach in the dam, reduce the opening degree e of the diversion tunnel gates, controlling the outflow through the diversion tunnel to be B to C times the inflow Q0. This will then raise the water level of the landslide-dammed lake again and increase the head of the floodwater at the breach, increasing the velocity of the overtopping flow and intensifying the erosion of the dam by the overtopping flow. If the depth of the breach exceeds H... t2 Alternatively, when tracing back to the source of the steep slope and reaching the breach of the landslide dam, the opening of the working gate e is increased again, and the discharge flow through the diversion tunnel is adjusted to D to E times the inflow flow Q0, so as to lower the water level of the landslide lake reservoir until the landslide dam breaches. This process continued until the landslide dam collapsed, and the water level of the landslide-dammed lake dropped to the elevation of the inlet of the diversion tunnel. Where 2≤D<E≤5.

[0018] Optionally, the inner wall of the diversion tunnel is made of concrete lining structure resistant to high-speed water flow erosion, and an air-entraining sill is provided on the tunnel section downstream of the working gate to prevent cavitation damage caused by high-speed water flow.

[0019] The method for regulating the outburst process of a landslide dammed lake provided by this invention has the following beneficial effects: First, traditional methods involve emergency response construction only after the landslide dam has formed, leaving a very short window (only about 1 week to 10 days for high-risk landslide dams). This invention, by constructing diversion tunnels beforehand, allows for artificial diversion through gates immediately after the landslide dam forms, delaying the rise in water level. This buys valuable days or even weeks for downstream evacuation, protection of critical facilities, and other subsequent emergency response work, effectively reducing the peak water level and the eventual breach flood peak. Second, traditional methods require the emergency excavation of large diversion channels on top of the dam, involving a large workload, high risk, and huge investment. This invention uses diversion tunnels to regulate the overtopping flow, guiding the dam breach through gradual scouring, restoring river connectivity, avoiding large-scale, high-risk dam top excavation, significantly reducing emergency response investment and the safety risks to construction workers, and minimizing negative social impact. Third, the current engineering community is helpless against the breaching process of landslide dams, forced to allow it to develop naturally and lead to a sudden collapse. This invention utilizes a diversion tunnel with a working gate for manual scheduling, continuously and synchronously controlling the outflow rate, water depth, and tunnel discharge rate of the overtopping water. Its core is to reduce the head and velocity of the overtopping water, weaken its scouring and destructive energy, and allow the sand and gravel in the dam body to be eroded slowly and gradually. This effectively delays the collapse and breach of the landslide dam, prolongs and smooths out the breach development process, and ultimately reduces the peak value of the breach flood, avoiding greater casualties and property losses caused by instantaneous super flood peaks. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the landslide dam failure flow rate and failure duration in the landslide dam failure process control method of this embodiment of the invention; Figure 2 This is a schematic diagram of the plan layout for the diversion tunnel of the landslide dam in an embodiment of the present invention; Figure 3 This is a schematic diagram of the initial stage of a landslide dam breach in an embodiment of the present invention; Figure 4 This is a schematic diagram of the source tracing stage of the landslide dam steep slope in an embodiment of the present invention; Figure 5 This is a schematic diagram of the rapid development stage of the landslide dam in an embodiment of the present invention (tracing the steep slope back to the breach of the landslide dam). Figure 6 This is a schematic diagram of the diversion tunnel structure in an embodiment of the invention.

[0021] Explanation of reference numerals in the attached figures: 1 is the typical high-risk landslide dam failure flow-failure duration development process curve; 2 is the landslide dam failure flow-failure duration development process curve based on the working gate scheduling of the diversion tunnel; 3 is the left bank of the river; 4 is the right bank of the river; 5 is the landslide dam; 6 is the diversion tunnel; 7 is the overtopping flow; 8 is the steep slope; 9 is the gate opening and closing machine room; 10 is the vertical shaft of the diversion tunnel; 11 is the working gate. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but these embodiments should not be construed as limiting the present invention.

[0023] This embodiment provides a method for regulating the process of a landslide dammed lake breach, including: Construct a diversion tunnel 6 at the location where a landslide dam 5 is expected to form, with the inlet of the diversion tunnel 6 located in the landslide lake upstream of the landslide dam 5 and the outlet of the diversion tunnel 6 located downstream of the landslide dam 5. A controllable opening working gate 11 is installed on the diversion tunnel 6; Once the landslide dam 5 is formed, the opening of the working gate 11 is controlled to regulate the outflow rate and head of the overtopping water 7, ensuring that the overtopping water has a low head and low velocity to scour the slope of the landslide dam, so as to achieve the safe release of floodwater by the landslide dam 5 and the gradual collapse and breach of the landslide dam 5 accumulation body.

[0024] Before the formation of the landslide dammed lake, a diversion tunnel 6 is constructed in the mountain to bypass the future location of the landslide dam 5, and an adjustable flow gate 11 is installed. When landslides, debris flows, or other disasters occur, forming the landslide dam 5 and blocking the river channel, the water level of the landslide dammed lake begins to rise. During the initial impoundment stage, the working gate 11 remains closed, and all upstream water is intercepted by the landslide dam 5, causing the reservoir water level to rise rapidly. During the initial overtopping intervention stage, when the reservoir water level is about to or has just overtopping the top of the landslide dam 5, operators remotely or on-site gradually open the working gate 11. Some of the upstream water is discharged downstream through the diversion tunnel 6, thus slowing down the rate of increase in the reservoir water level. This keeps the initial head of the overtopping flow 7 at a low level, and the flow velocity and scouring force of the overtopping flow 7 are significantly reduced. During the breach control stage, as the water level continues to rise, the proportion of the overtopping flow 7 and the tunnel discharge can be dynamically allocated by finely adjusting the opening of the working gate 11. Increasing the tunnel discharge can lower the reservoir water level and the overtopping head, weakening the scouring of the dam body; decreasing the tunnel discharge allows the reservoir water level to rise appropriately, increasing the overtopping head and maintaining a certain scouring capacity. Through this "artificial diversion" scheduling, this embodiment achieves precise control over the scouring energy of the overtopping flow 7, making it no longer an uncontrollable "unrestrained scouring" but a "gradual and guideable" scouring process, thereby guiding the landslide dam 5 to collapse slowly and orderly in the intended manner.

[0025] First, traditional methods involve emergency construction only beginning after the landslide dam has formed, leaving a very short window of opportunity (only about 1 week to 10 days for high-risk landslide dams). This embodiment, by constructing a diversion tunnel 6 beforehand, allows for artificial diversion through gates immediately after the landslide dam forms, delaying the rise in water level. This buys valuable days or even weeks for downstream evacuation, protection of critical facilities, and other subsequent emergency response efforts, effectively reducing the peak water level and the eventual breach peak. Second, traditional methods require the emergency excavation of a large diversion channel on top of the dam 5, a large-scale, high-risk, and costly undertaking. This embodiment utilizes the diversion tunnel 6 to regulate the overtopping flow, guiding the dam 5 to breach gradually through scouring, restoring river connectivity, avoiding large-scale, high-risk dam top excavation, significantly reducing emergency response costs and worker safety risks, and minimizing negative social impact. Third, the current engineering community is largely helpless in controlling the breaching process of landslide dams, leaving them to develop naturally and eventually collapse. This embodiment utilizes a diversion tunnel 6 with a working gate 11 for manual scheduling, continuously and synchronously controlling the discharge flow / depth of the overtopping water flow 7 and the discharge flow through the tunnel. Its core purpose is to reduce the head and velocity of the overtopping water flow 7, weakening its scouring and destructive energy, allowing the dam's aggregate to be eroded slowly and gradually. This effectively delays the collapse and breach of the landslide dam 5, prolonging and smoothing the breach development process, ultimately reducing the peak value of the breach flood and preventing wider casualties and property damage caused by a sudden, massive flood peak.

[0026] Preferably, on the side of the river with relatively better engineering geological conditions on both sides of the estimated landslide dam 5, a diversion tunnel 6 is constructed artificially.

[0027] Before constructing the diversion tunnel 6, the historical scale of the landslide dam was statistically analyzed to preliminarily assess the future scale and location of the landslide dam 5, and to predict the maximum backwater level H of the landslide dam. max The backwater length L and the inflow rate Q0 are considered. This embodiment is not a passive response to sudden disasters, but rather an active identification of regional geological risks. By statistically analyzing the scale and location of landslide-dammed lakes that have historically occurred in a certain river section, and combining this with topographical and geological conditions, a preliminary assessment can be made of the location most likely to form a landslide-dam 5 and its maximum possible volume. Based on this, hydrological and hydraulic methods are used to predict the maximum backwater level (H) that the landslide-dammed lake may reach under specific inflow rates (such as the average flow rate during the flood season or the flow rate of a certain frequency) once the river is blocked. max Key parameters include the length of the return water (L). These parameters provide the scientific basis for the subsequent site selection, scale, and elevation design of the diversion tunnel 6.

[0028] Scientific assessment and forecasting were conducted before the construction of diversion tunnel 6, transforming the project planning from a "blind response" to a "targeted approach." This involved forecasting H...max L and Q0 can ensure that the constructed diversion tunnel 6 is matched with the actual disaster scale in terms of capacity, elevation and discharge capacity, avoiding project failure due to insufficient design capacity (such as the tunnel inlet elevation being too low, leading to early siltation, or too high, leading to ineffective diversion; insufficient discharge capacity, resulting in inability to control water level) or unnecessary investment waste due to over-design.

[0029] The site selection requirements for the construction of diversion tunnel 6 are as follows: the distance L1 between the inlet of diversion tunnel 6 and the upstream slope of the estimated landslide dam 5 is in the range of 0 to 1 / 2L, and the distance L2 between the outlet of diversion tunnel 6 and the downstream toe of the estimated landslide dam 5 is controlled at around 200-500m.

[0030] The selection of the inlet and outlet locations of the diversion tunnel 6 is crucial to its effective operation. Inlet location (L1): The inlet is positioned within 0 to 1 / 2 of the backwater length from the upstream slope of the estimated landslide dam 5. If L1=0, meaning the inlet is close to the landslide dam 5, it can extract water with high sediment content (potentially causing blockage) or high water levels upstream of the dam most quickly. If L1>0, the inlet is located within the landslide lake reservoir area. Positioning the inlet in the first half of the backwater length ensures that the inlet remains submerged even before the water level in the landslide lake reaches its maximum, allowing it to function early and continuously while avoiding direct impact from dam failure or landslide surges due to its proximity to the dam body. Outlet location (L2): The outlet is positioned 200-500 meters downstream of the estimated landslide dam 5 at the dam toe. This distance ensures that the high-speed water jet from the tunnel has enough space to dissipate energy in the river channel, avoiding direct scouring of the dam toe and hollowing out the foundation of the landslide dam, which could lead to an unexpected and sudden collapse. It also ensures that the water jet from the tunnel can quickly flow into the main river channel, restoring the continuity of the downstream river flow.

[0031] A suitable site selection is the spatial basis for the effective functioning of the diversion tunnel 6. Precisely defining the inlet and outlet locations aims to optimize hydraulic conditions and engineering safety. The inlet location ensures the tunnel remains submerged and situated in a relatively dynamically stable area of ​​the reservoir. The outlet location represents a trade-off: too close a distance would allow the high-speed water flow to directly damage the downstream slope of the dam 5, triggering an uncontrollable and rapid collapse; too far a distance would necessitate the excavation of a longer tunnel, increasing the workload and investment. A distance of 200-500 meters has proven to be the optimal balance between engineering safety, economy, and hydraulic energy dissipation requirements.

[0032] The diversion tunnel 6 includes an inlet section, a control section, a tunnel body section, and a flood discharge and energy dissipation section. The inlet and control sections are kept horizontal, and the elevation of the bottom plate of the inlet and control sections is H2, which is higher than the riverbed siltation elevation. The longitudinal slope i of the tunnel body section is controlled at approximately 0.05 to 0.1. The maximum discharge capacity of the diversion tunnel is Q. S The maximum discharge capacity Q of the diversion tunnel is required. SThe inflow rate reached 2 to 5 times that of the landslide dammed lake, Q0.

[0033] The bottom elevation being higher than the siltation elevation ensures the reliability of the gate (preventing siltation). A gradient in the tunnel section ensures smooth flow and self-draining capacity. Most importantly, the maximum discharge capacity Q is maximized. S Set to 2 to 5 times the inflow rate, the diversion tunnel 6 possesses a "super discharge capacity" in critical moments. This allows operators not only to "fine-tune" the water level, but also to "forcefully discharge" the water during the momentary collapse of the landslide dam 5, instantly and significantly reducing the reservoir water level and the overtopping head, "holding back" the impending uncontrollable collapse process, thus turning a passive situation into an active one and truly achieving control over the collapse process.

[0034] The control section is equipped with a working gate 11, and a water intake tower and a gate hoisting room 9 are located on top of the control section. The opening degree e of the working gate is controlled through the gate hoisting room 9 and the water intake tower. Setting the elevation of the gate hoisting room 9 platform above the highest flood level is a classic safety principle in water conservancy projects. This ensures that at the critical moment when the landslide dam water level is highest, the risk of breach is greatest, and human intervention is most needed, the control system itself will not fail due to flooding, thus guaranteeing the effectiveness of intervention measures. The stable operating environment (the gate hoisting room 9 located above the water surface) allows operators to calmly and precisely adjust the gate opening degree e without being threatened by severe weather and floods, achieving refined control of the flow rate.

[0035] The platform elevation H1 of the hoist room is higher than the maximum water level H of the landslide dam. max 5-10m.

[0036] After the landslide dam 5 is formed, the opening degree of the working gate 11 is controlled to regulate the outflow rate and head of the overtopping water 7 of the landslide dam 5, so as to achieve the safe release of floodwater impounded by the landslide dam 5 and the gradual collapse and breach of the landslide dam 5 accumulation body, including: During the period when the landslide dam 5 blocked the river channel and the reservoir water level continued to rise, the working gate 11 was closed; When the water level of the landslide dam reservoir gradually rises to the top of the landslide dam 5, the working gate 11 is opened, the opening degree e of the working gate is increased and adjusted, and the discharge flow Q1 from the diversion tunnel is controlled between 0 and A and the inflow flow Q0. Wait until the water level of the landslide-dammed lake rises to the top of the landslide dam (5H). t1 At the same time, continuously increase the opening degree e of the working gate to control the discharge flow Q1 of the diversion tunnel to be within the inflow flow Q0 of A to B; Wait until the water level of the landslide-dammed lake rises to the top of the landslide dam (5H). t1 ~H t2 At the same time, the opening degree e of the working gate is continuously increased and adjusted to control the discharge flow Q1 of the diversion tunnel to be B to C times the inflow flow Q0. Where 0 < A < B < C ≤ 1, 0 < Ht1 ≤0.2<H t2 ≤0.5m.

[0037] Preferably, A = 1 / 3, B = 1 / 2, C = 1; H t1 =0.2m, H t2 =0.5m.

[0038] By strictly and progressively controlling the overtopping water depth to extremely low levels of 0.2 meters and 0.5 meters, the disastrous water head of 3-8 meters in traditional techniques was successfully transformed into a gentle and controllable "shallow flood." This "shallow flood" has very low scouring energy, only slowly eroding the surface of the dam without triggering deep, large-scale shear failure. This transformed the failure process of the landslide dam 5 from an uncontrollable, instantaneous disaster into a controllable, gradual process lasting several hours or even days, buying precious response time for downstream areas.

[0039] The method for controlling the landslide dam breach also includes: constantly monitoring the development of the landslide dam breach and the water depth at the breach of dam 5; and adjusting the opening degree e of the working gate of the diversion tunnel 6 based on the water depth at the breach of dam 5 and the location of the headwaters slope 8 to ensure that the maximum water depth at the breach of dam 5 is controlled within H. t2 Within the scope of the dam and the control of the steep slope 8 at the source of the landslide dam 5, once the water depth at the crest of the landslide dam 5 breaches, exceeding the height H... t2 Alternatively, by tracing back from the steep embankment 8 to the breach of the landslide dam 5, the opening of the working gate e of the diversion tunnel 6 can be increased.

[0040] By setting clear physical indicators (H) t2 Based on the 0.5m (points) and geometric indicators (location of the source slope 8), operators can objectively and promptly assess the risk of a dam failure and intervene immediately by simply increasing the gate opening. This ensures that the entire failure process remains within the preset safety boundaries, effectively preventing the risk of sudden overtopping of the dam due to unforeseen circumstances (such as partial dam collapse or a surge in upstream flow) or rapid backflow of the source slope 8, which could lead to an instantaneous overall collapse of the dam. This achieves proactive and safe control over the failure process.

[0041] The methods for controlling the landslide dam breach process also include: When the downstream steep slope 8 of the landslide dam 5 develops back to the breach of the landslide dam 5, the opening of the working gate e is continuously increased, and the discharge flow of the diversion tunnel is controlled to be D to E times the inflow flow Q0, so as to quickly reduce the water level of the landslide lake and reservoir and the head of the floodwater at the breach of the landslide dam 5, reduce the flow velocity of the overpass flow 7, and slow down the scouring of the landslide dam 5 by the overpass flow 7. Once the water level of the landslide-dammed lake has dropped to the level of the breach in dam 5, reduce the opening e of the gate in the diversion tunnel 6, controlling the outflow through the diversion tunnel to be B to C times the inflow Q0. This will raise the water level of the landslide-dammed lake again and increase the head of the floodwater at the breach in dam 5, increasing the velocity of the overtopping flow 7 and intensifying the erosion of the dam 5 by the overtopping flow 7. Once the depth of the breach exceeds H... t2 Alternatively, when tracing back from the steep shoal 8 to the breach of the landslide dam 5, the opening of the working gate e is increased again, and the discharge flow through the diversion tunnel is adjusted to D to E times the inflow flow Q0, so as to lower the water level of the landslide lake reservoir until the breach of the landslide dam 5 is reached. This process continued until the landslide dam 5 collapsed, and the water level of the landslide lake reservoir dropped to the elevation of the intake of the diversion tunnel 6. Where 2≤D<E≤5.

[0042] Preferably, D=2 and E=5.

[0043] The "forced drainage mode" (2-5 times Q0) can significantly reduce the reservoir water level within tens of seconds to minutes, eliminating the high-head scouring conditions that lead to instantaneous collapse at the source. This is unparalleled by any traditional technology. "Water level seesaw" control is a novel and highly efficient dam-breaking technology. It abandons the traditional methods of passively waiting for the water flow to naturally breach the dam (often leading to instantaneous collapse) or simply lowering the water level (too slow a breach). By actively creating multiple, controllable "micro-overflow" events, it achieves repeated and precise adjustments to the breach morphology, ensuring both the continuity of the breach process and that each step remains within a safe and controllable range. This "gradual squeezing" breach ultimately results in a smoother breach flood peak process line, a lower peak value, and minimal impact on downstream areas. The entire process is essentially "using the water in the reservoir to breach the dam." Through gate regulation, the potential energy stored in the landslide dam is converted into a series of controllable energy bursts to cut the dam, ultimately released in a targeted manner, achieving the orderly transformation and reduction of disaster energy.

[0044] The inner wall of the diversion tunnel 6 is constructed with a concrete lining structure resistant to high-speed water flow erosion, and an air-entraining sill is installed on the tunnel section downstream of the working gate 11 to prevent cavitation damage caused by high-speed water flow. This invention requires the diversion tunnel 6 to have an ultra-large flood discharge capacity (Q) of 2-5 times the inflow rate. S When the "forced drainage mode" is activated, the water flow velocity inside the tunnel may reach or even exceed 20 m / s, placing it in a dangerous zone highly susceptible to cavitation damage. The combined protective measures of erosion-resistant concrete and aerated retaining walls provide double insurance for this "super flood discharge channel," enabling it to safely and undamaged withstand multiple high-intensity flood discharges and ensuring the structural stability and reliability of the project during several cycles of water level fluctuations.

[0045] The inlet section of the diversion tunnel 6 is equipped with a trash rack to prevent floating debris from entering the tunnel and clogging the gates or affecting the discharge capacity. While the trash rack appears to be a simple design, it is crucial to the reliability of the entire system. It effectively avoids two fatal malfunctions: first, floating debris can clog or jam the working gate 11, preventing it from opening and closing properly, leading to the failure of the entire control system; second, a large amount of floating debris can partially block the tunnel, reducing its actual discharge capacity, causing the "forced discharge mode" or "water level seesaw" strategy to fail due to insufficient flow, and potentially leading to more serious accidents due to the accumulation of floating debris at the gates. Therefore, the trash rack is a fundamental guarantee that all the advanced functions and strategies of this invention can be effectively implemented, significantly improving the system's operational reliability in real harsh environments.

[0046] In this embodiment, the principle of the landslide dam breach control method is as follows: In response to the development of the landslide dam breach, artificial diversion was implemented through the diversion tunnel 6 to regulate the head and discharge flow of the overtopping flow 7 at the top of the landslide dam 5. When the head of the overtopping flow 7 reached 0.5m-1m or the steep bank 8 reached the breach of the landslide dam 5, the working gate 11 of the diversion tunnel 6 was rapidly opened to increase the discharge flow, quickly lowering the water level of the landslide dam reservoir. This, in turn, reduced the head and discharge flow of the overtopping flow 7 at the top of the landslide dam 5, thus mitigating the impact of the breach. The slow-breaking flow erodes the slope of dam 5, preventing a rapid collapse of dam 5 and a torrential outflow of water from the landslide dam lake. When the water level in the landslide dam lake drops to the breach point of dam 5, the outflow through diversion tunnel 6 is reduced, and the water level in the landslide dam lake is raised, causing dam 5 to overflow again. The overflowing water head and outflow gradually increase, eroding the remaining sand and gravel on the slope of dam 5. The overflowing water head then rises again to overshoot the dam. When the breach in the remaining body of landslide dam 5 reaches 0.5m to 1m or the steep slope 8 is traced back to the breach in the remaining body of landslide dam 5, the working gate 11 of the diversion tunnel 6 is quickly opened to increase the discharge flow in the diversion tunnel 6, rapidly reducing the water level of the landslide lake reservoir. This reduces the head and discharge flow of the water flowing over the top of landslide dam 5, slowing down the scouring of the dam slope by the breaching water, and preventing the rapid breach of landslide dam 5 and the "pouring out" of the water stored in the landslide lake. This process is repeated, utilizing... The diversion tunnel 6 and the working gate 11 are manually operated to divert the water, regulate the head and discharge flow of the overtopping water 7 of the landslide dam 5, and gradually scour the landslide dam 5 by forming small flow and low head overtopping water 7 multiple times. This prolongs the development process of the landslide dam breach and avoids the instantaneous collapse of the landslide dam 5 and the one-time "pouring" of floodwater stored in the landslide dam. In this way, it can both reduce the flood peak of the landslide dam breach and scour and transport the deposits of the landslide dam 5 and restore the connectivity of the river channel.

[0047] refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 , Figure 1 This is a schematic diagram of the landslide dam failure flow-failure duration in the landslide dam failure process control method of this invention. Figure 2 This is a schematic diagram of the plan layout for the diversion tunnel of the landslide dam in an embodiment of the present invention. Figure 3 This is a schematic diagram of the initial stage of a landslide dam breach in an embodiment of the present invention. Figure 4 This is a schematic diagram of the source tracing stage of the landslide dam steep slope in an embodiment of the present invention. Figure 5 This is a schematic diagram of the rapid development stage of the landslide dam in an embodiment of the present invention (tracing the steep slope back to the breach of the landslide dam). Figure 6 This is a schematic diagram of the diversion tunnel structure in the embodiment of the invention. As can be seen from the typical high-risk landslide dam burst flow-burst duration development process curve 1, if the burst process of the landslide dam 5 is not controlled, the maximum burst flow Q of the typical high-risk landslide dam will be... max1 A breach is likely to occur, potentially leading to a breach flood peak. As shown in curve 2 (the development process curve of the breach flow-breach duration of the landslide dam based on the working gate 11 of the diversion tunnel 6), controlling the breach process of the landslide dam 5 to achieve the maximum breach flow of the landslide dam based on the working gate 11 of the diversion tunnel 6 can generate multiple smaller breach flood peaks, significantly improving the safety of the landslide dam breach process control method. Figure 2 This illustrates that the water flow during the breach process can be expressed as the outflow rate Q from the overtopping of the landslide dam. m The longitudinal slope i of the diversion tunnel 6, the left bank 3 of the river, the right bank 4 of the river, and the discharge flow Q1 of the diversion tunnel. Figure 3 , Figure 4 and Figure 5 The diagram shows the water level of the landslide-dammed lake reservoir (H0) and the water depth at the breach of the landslide dam (h1). Figure 6 The diagram shows the gatehouse 9, the diversion tunnel shaft 10, and the working gate 11.

[0048] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method for regulating a dammed lake outburst process, characterized in that, include: Construct a diversion tunnel at the location where a landslide dam is expected to form, with the tunnel inlet located in the landslide lake upstream of the dam and the tunnel outlet located downstream of the dam. A controllable opening working gate is installed on the diversion tunnel; Once the landslide dam is formed, the opening of the working gate is controlled to regulate the outflow and head of the overburden, ensuring that the overburden has a low head and low velocity to scour the slope of the landslide dam, thereby achieving the safe release of floodwater and the gradual collapse and breach of the landslide dam's accumulation.

2. The dammed lake breaching process regulation method of claim 1, wherein, Before constructing the diversion tunnel, the historical size of the landslide dam was statistically analyzed to preliminarily assess the future size and location of the landslide dam, and to predict the maximum backwater level H of the landslide dam. max , return water length L, inflow rate Q0.

3. The dammed lake breaching process regulation method of claim 2, wherein, The site selection requirements for the construction of diversion tunnels are as follows: the distance L1 from the inlet of the diversion tunnel to the upstream slope of the estimated landslide dam should be in the range of 0 to 1 / 2L, and the distance L2 from the outlet of the diversion tunnel to the downstream toe of the estimated landslide dam should be controlled at around 200-500m.

4. The dammed lake breaching process regulation method of claim 2, wherein, The diversion tunnel includes an inlet section, a control section, a tunnel body section, and a flood discharge and energy dissipation section. The inlet and control sections are horizontal, and the elevation of their floor slabs (H2) is higher than the riverbed siltation elevation. The longitudinal slope (i) of the tunnel body section is controlled at approximately 0.05–0.

1. The maximum discharge capacity of the diversion tunnel is Q. S The maximum discharge capacity Q of the diversion tunnel is required. S The inflow rate reached 2 to 5 times that of the landslide dammed lake, Q0.

5. The dammed lake breaching process regulation method of claim 4, wherein, The control section is equipped with a working gate, and the top of the control section is equipped with an intake tower and a gate opening and closing machine room. The opening degree e of the working gate is controlled through the gate opening and closing machine room and the intake tower.

6. The dammed lake breaching process regulation method of claim 5, wherein, The platform elevation H1 of the hoist room is higher than the maximum dammed lake water level H max 5~10m.

7. The dammed lake breaching process regulation method of claim 2, wherein, Once a landslide dam forms, the opening of the working gates is controlled to regulate the outflow and head of the overburden, ensuring low head and low velocity of the overburden water to scour the dam slope. This achieves the safe release of floodwater and the gradual collapse and breaching of the landslide dam's accumulation mass, including: When a landslide dam blocks a river channel and the reservoir water level remains high, the working gates are closed. When the water level of the landslide dammed lake gradually rises to the top of the dam, the working gate is opened, the opening degree e of the working gate is increased and adjusted, and the discharge flow Q1 from the diversion tunnel is controlled between 0 and A and the inflow flow Q0. When the water level of the dammed lake is raised to the top of the dam H t1 The working gate opening e is continuously increased, and the discharge flow Q1 of the diversion tunnel is controlled to be the inflow Q0 of the dammed lake at A~B. When the water level of the dammed lake is raised to the top of the dam H t1 ~H t2 The working gate opening e is continuously increased and regulated, and the discharge flow Q1 of the diversion tunnel is controlled to be B~C times of the inflow flow Q0. Where 0 < A < B < C ≤ 1, 0 < H t1 ≤0.2<H t2 ≤0.5m.

8. The dammed lake breaching process regulation method of claim 7, wherein, Also includes: Continuously monitor the development of the landslide dam breach and the water depth at the breach opening. Based on the water depth at the breach opening and the location of the headwaters slope, adjust the opening degree e of the diversion tunnel gate to ensure that the maximum water depth at the breach opening is controlled within H. t2 Within the affected area and along the source slope, the water depth at the crest of the landslide dam is controlled on the downstream slope. If the landslide dam breaches, the water depth will exceed the specified height (H). t2 Alternatively, by tracing the steep slope back to the breach of the landslide dam, the opening degree e of the working gate of the diversion tunnel can be increased.

9. The dammed lake breaching process regulation method of claim 8, wherein, Also includes: When the downstream steep slope of the landslide dam develops back to the breach of the landslide dam, the opening of the working gate is continuously increased by e, and the discharge flow of the diversion tunnel is controlled to be D to E times the inflow flow Q0, so as to quickly reduce the water level of the landslide lake and reservoir and the head of the flooded water flow at the breach of the landslide dam, reduce the flow velocity of the overburden flow, and slow down the scouring of the landslide dam by the overburden flow. Once the water level of the landslide-dammed lake has dropped to the level of the breach in the dam, reduce the opening degree e of the diversion tunnel gates, controlling the outflow through the diversion tunnel to be B to C times the inflow Q0. This will then raise the water level of the landslide-dammed lake again and increase the head of the floodwater at the breach, increasing the velocity of the overtopping flow and intensifying the erosion of the dam by the overtopping flow. If the depth of the breach exceeds H... t2 Alternatively, when tracing back to the source of the steep slope and reaching the breach of the landslide dam, the opening of the working gate e is increased again, and the discharge flow through the diversion tunnel is adjusted to D to E times the inflow flow Q0, so as to lower the water level of the landslide lake reservoir until the landslide dam breaches. This process continued until the landslide dam collapsed, and the water level of the landslide-dammed lake dropped to the elevation of the inlet of the diversion tunnel. Where 2≤D<E≤5.

10. The dammed lake breaching process regulation method of claim 1, wherein, The inner wall of the diversion tunnel is made of concrete lining structure that is resistant to high-speed water flow erosion, and an air-entraining sill is set in the tunnel section downstream of the working gate to prevent cavitation damage caused by high-speed water flow.

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