Research On The Application Of Array Anchor Technique In The Levee Breach Plugging

Levee breaches caused by flood during flood season seriously threaten local agriculture,transportation,ecological environment and the safety and stability of society.It has extremely important engineering application value and urgent practical significance to study the mechanism of levee breaches and the new technology of emergency plugging.At present,it is urgent to improve the emergency plugging method of sinking ships and sinking trucks.Fast,safe and efficient plugging technology must solve two key problems: rapid rooting and rapid expansion of plugging projectile at breaching mouth.In this paper,the feasibility of the new technology of plugging based on Array-Rocket-Anchor was analyzed and demonstrated through a series of theoretical analysis and model test studies.The main tasks are as follows:(1)The generalization analysis of the eigenvalue of levee break and the determination of the hydraulic boundary elements of typical breach.Based on more than 100 groups of domestic and foreign examples and test data of embankment/earth dam failure,the correlation between the hydraulic boundary eigenvalues of the breach was studied based on cluster analysis approach,and the missing values were imputed after correlating and fitting.At the same time,the hydraulic boundary parameters and related equations of generalized typical breach are obtained through the statistical analysis of probability density of dimensionless eigenvalues of the breach.The analysis shows that the width of the breach is mostly in 20 ~100 m,the water head of the breach is in 4~12 m,the velocity of the breach is in 2 – 8 m/s,and all of those distribution probabilities are in 64%-71%.The probability density of both the width-to-depth ratio and the Froude number of the breach are subject to the normal distribution characteristics,and the distribution frequency of the width-to-depth ratio of 3-8 is about 55%,and the Froude number's of 0.4-0.8 is about 60%.(2)Model experiment and research on hydraulic characteristics of typical breach.Based on the generalization results of typical breach eigenvalue,a 1:50 typical breach physical model was established in the laboratory,and according to different test conditions,the measurement tests of the eigenvalue parameters(water-head difference inside and outside the levee,the center velocity of the breach,the depth of the breach,etc.)were carried out,and the relationship between equivalent water head diffence with single-width stream power and equivalent water depth is studied and discussed,and the change law of water level-water flow,water level-velocity in the upstream and downstream of the breach.The flow state and surface velocity field of the river,the breach and the floodplain are measured by using the Velocity Distribution Measuring System(VDMS),and the change feature of the velocity field in the middle and later period was analyzed according to the complex flow state around the breach when the levee is broken,and the test shows that the flow rate at the breach mouth is the largest,the velocity rate is generally 4.81-5.80m/s(the relative error is within 4%),and there is a wide range of vortex phenomenon in the floodplain on both sides of the lower breach,the velocity is generally 0.64~0.92m/s.(3)A series of simulation tests were carried out to study the feasibility of new technology of breach plugging.The construction process of plugging is put forward based on the design idea of the new plugging technology of array anchor is put forward.A simulated experimental study on the feasibility of new technology was carried out.The motion law of using anchor cable sliding gabion is analyzed,and gets the critical velocity of gabion with different specifications.And the tensile test of single anchor cable was carried out in the sink,and the correlation between the tensile force of cable with the weight of the gabion,the horizontal angle of the cable and the velocity of the breach are studied and analyzed,and the function relation formula is put forward: F~f(G',v,?).The method of optimizing anchor array arrangement of “staggered anchoring matrix toward the upstream” based on the new plugging technology idea of array rocket anchor is put forward,and the corresponding simulation test study and analysis in the breach model are carried out.The test results show that the use of new technology for accurate plugging with anchor cable can quickly form plugging mainstay,the loss rate of material can be controlled within 4%,plugging efficiency is very significant;and the plugging time is related to the water head difference inside and outside the embankment,the vilocity of the breach and the depth of the downstream side of the plugging body.