12 results about "Limit analysis" patented technology

The invention belongs to the field of geological disaster prevention and control, and particularly discloses a slope safety coefficient calculation method considering an upward inclined drainage hole, which comprises the following steps: establishing a slope seepage numerical simulation model containing the upward inclined drainage hole, and obtaining space coordinates of nodes in a slope and pore water pressure data through finite element calculation; generating a potential slip plane based on an upper limit theorem of limit analysis, and calculating a pore water pressure value at each discrete point on the potential slip plane by using a Kriging interpolation method and taking node space coordinates and pore water pressure data as samples; according to the potential slip plane, the soil body strength parameter and the pore water pressure value obtained through interpolation, a balance equation of the soil body gravity power, the pore water pressure power and the internal energy dissipation power when the slope is in the critical failure state is established; and solving the balance equation to obtain the slope safety coefficient considering the inclined drainage hole. According to the method, the slope safety coefficient considering the inclined drainage hole can be efficiently and accurately calculated.

The invention discloses an automatic searching method for a sliding surface of a soil-rock aggregate slope, relates to the technical field of geotechnical engineering slopes, and is characterized in that a new automatic searching method for the sliding surface of the soil-rock aggregate slope is provided, and based on a limit analysis upper-bound method and a graph theory method, the stone winding effect of an instability path can be considered, and the stability of the sliding surface of the soil-rock aggregate slope is improved. And the most dangerous sliding surface of the earth-rock aggregate slope is quickly searched, so that the safety coefficient of the earth-rock aggregate slope is obtained. According to the method, the key problem that the sliding surface is difficult to obtain under the influence of the stone content and the block stone position is solved, a theoretical method capable of rapidly obtaining the critical sliding surface of the earth-rock mixture slope and carrying out stability analysis is provided, and theoretical support can be provided for slope design and landslide disaster prevention and reduction.

The application discloses a kind of minimum safety distance determination method and system of tunnel excavation face crossing gob area, method includes the following steps: set the failure mode of tunnel excavation face instability under the condition that coal mine gob area is contained in stratum, and establish theoretical model based on failure mode;Minimum safety distance condition is judged based on theoretical model;The shape of the failure region is optimized, and the optimal solution of minimum safety distance is obtained based on minimum safety distance condition.The application proposes a failure mode suitable for the instability of tunnel excavation face crossing coal mine gob area, and the analytical solution of minimum safety distance is derived using the upper bound method of limit analysis.Compared with numerical simulation and analytical solution, the model proposed by the application has high precision and can reflect the mechanism of tunnel excavation face instability and failure.

The invention discloses a data and physics dual-drive balance weight type road shoulder retaining wall soil pressure prediction method, which comprises the following steps: firstly, constructing a self-adaptive finite element limit analysis reference model to obtain wall back soil pressure and a fracture surface form, and then extracting a physical rule in combination with a classic soil pressure theory and converting the physical rule into a differentiable mathematical constraint; generating a multi-working-condition structured data set through Latin hypercube sampling in combination with the reference model; and then establishing a physical information neural network model fused with physical constraints, screening out an optimal model through hyper-parameter optimization and batch training, and finally loading the model to realize soil pressure prediction. According to the method, physical constraints are embedded into the neural network, dependence on measured data is reduced, physical consistency is still kept in a data sparse region, soil pressure and fracture surface dip angle parameters of all parts of the wall back can be synchronously output, prediction precision and generalization ability are greatly improved, a comprehensive basis is provided for fine design of the retaining wall, and the rapid design requirement of a project is met.

This invention provides a quasi-regular double-six discontinuous triangular mesh construction method for searching potential slope sliding surfaces, comprising: iteratively generating a quasi-regular initial triangular mesh adapted to the slope model boundary; locally dividing into six meshes to generate a six-directional arrayed topological mesh; constructing a data format of six-node triangular elements and high-order discontinuities; and solving the potential slope sliding surface using a second-order cone programming model. This invention adapts to the geometric boundaries of discrete slope models and meets the special requirements of the quasi-regular double-six discontinuous triangular mesh, forming a six-directional continuous discontinuous mesh structure within any small region. Furthermore, the double-six discontinuous mesh can be further pre-defined with local partitions, reducing resource consumption of mesh elements in non-critical areas. Applied to the upper limit finite element method of limit analysis, it achieves high-precision searching of potential slope sliding surfaces through rapid solving of the second-order cone programming problem, thus reducing computational burden while maintaining search accuracy.

The application discloses a kind of plate pile embedded stability evaluation method of foundation pit considering unsaturated effect.Model test and numerical simulation results show that the failure sliding surface of foundation pit is the combination of curve and straight line, and the combination is not yet applied to the research of unsaturated foundation pit stability at present.Based on the upper limit principle of limit analysis, a kind of horizontal piece half analytical analysis method is proposed, the external power done by unsaturated soil gravity is calculated using this method, and based on the maximum energy consumption principle, the explicit semi-analytical solution of the moment of the lowest way of internal support point by active and passive earth pressure is obtained, and then the stability safety factor of plate pile embedded foundation pit is obtained.The semi-analytical analysis method constructed by the application has the advantages of analytical method and numerical method, effectively combines the unsaturated soil strength theory with limit analysis method, can reasonably explain the strengthening mechanism of suction effect, and has certain practical guiding significance for guiding the design and excavation of foundation pit under complex conditions.

The invention discloses a slope stability analysis method considering anchor cable performance degradation under the action of an earthquake. The method comprises the following steps: constructing an anchored rock slope multi-slider geometric model based on a limit analysis upper-bound method; based on the safety coefficient, the anchor cable limit state and the failure mode, the slope dynamic response is divided into three stages of anchor cable elastic coordination response, elastic response and anchor cable plastic yield and failure; establishing a multi-degree-of-freedom concentrated mass-spring-damping power model; the performance degradation characteristic of the anchor cable is introduced, and the displacement of each sliding block under the earthquake action is calculated; by analyzing the relative acceleration and displacement between the adjacent sliding blocks, the action mode between the sliding blocks is judged in real time, and integrated solution of sliding body displacement, dynamic evolution of the safety coefficient and anchor cable performance degradation and failure judgment under the earthquake action is achieved. According to the method, the elastic-plastic evolution and performance degradation of the anchor cable and the dynamic coupling effect among the multiple sliding blocks under the near-fault earthquake action can be effectively represented, and the accuracy of anchoring slope stability evaluation under the earthquake action is remarkably improved.

This invention discloses a simplified analysis method for the heave stability of unsaturated foundation pits. Addressing the heave stability problem of unsaturated foundation pits, a simplified analysis method based on the upper limit principle of limit analysis is proposed. The Prandtl failure mechanism is used to assess the heave stability of the foundation pit, calculating the velocity field of all sliding soil masses and the external power exerted by soil gravity. Based on the velocity field of the sliding soil masses, the total energy dissipation rate caused by the apparent cohesion of the unsaturated soil is calculated, and the safety factor for the heave stability of the foundation pit is obtained based on the principle of increased unit weight. Compared with existing technologies, this invention effectively combines the unsaturated soil strength theory with the limit analysis method, providing a reasonable explanation for the strengthening mechanism of suction effect in the heave stability problem of foundation pits. This has practical guiding significance for the design and excavation of foundation pits under complex conditions.

The invention relates to the technical field of underground engineering stability analysis, and discloses a city gate opening type tunnel three-dimensional excavation face stability upper limit analysis method which comprises the steps that a city gate opening type tunnel three-dimensional geometric failure model is established, and a symmetric plane and a radial plane with a rotating shaft as the center are defined; discretizing an excavation surface into a plurality of unit nodes by adopting a spatial discretization technology, and iteratively calculating discrete point coordinates of a failure mechanism through a speed compatibility condition; based on an energy conservation principle, calculating external force acting power and an energy dissipation rate, and deducing a critical support pressure upper limit solution; and rotating parameters beta A and beta B are optimized through a genetic algorithm, and the most dangerous instability mode and the minimum support pressure are determined. According to the method, on the basis of the limit analysis upper limit theorem and the associated flow rule, the high-order difference scheme spatial discretization technology is adopted to capture and calculate control nodes, the three adjacent nodes and the projection points of the nodes on the symmetry plane form a calculation unit, and the problem of stability calculation of the urban gate opening type tunnel three-dimensional excavation face under the complex geometric boundary is solved.

The invention discloses an embankment slope stability evaluation method under rainfall and cyclic vehicle-mounted action, and belongs to the technical field of slope stability evaluation of road engineering. According to the method, a three-stage limit analysis framework is adopted, and closed expression and rapid evaluation of the safety coefficient of the embankment are achieved through unsaturated seepage field solving, stress field coupling and spiral failure mechanism analysis. In general, through combination of multi-physics field coupling, a nonlinear strength criterion and an energy balance principle, the stability evaluation precision and calculation efficiency of the embankment slope under the complex environment and load effect are remarkably improved, and the method has important theoretical value and engineering application prospects.

The invention discloses a soil tunnel vault caving mode calculation method based on a limit analysis upper bound method, relates to the technical field of tunnel caving calculation, and solves the technical problem that the accuracy of a corresponding tunnel vault caving theoretical solution is low due to the fact that the prior art stays on a theoretical solution mode based on an ideal elastic-plastic constitutive model. The method comprises the following steps: S1, constructing a geometric model to describe a section boundary of a tunnel collapse block; s2, calculating external force power W made by the gravity of the collapse block by adopting an upper limit analysis method based on the geometric model for describing the boundary, calculating internal energy dissipation rate D along the collapse boundary through a modified Cambridge model, and constructing an equilibrium equation between the external force power W and the internal energy dissipation rate D; s3, carrying out optimization solution on the balance equation by adopting a variational method, and determining a function expression which enables the balance equation to be established; s4, determining the caving range of the tunnel vault based on the function expression. The method has the advantages that the theoretical solving result is more accurate, and the like.

This application discloses a method for predicting the strong seismic stability of high mountains, relating to the field of rock mass engineering geological dynamics. The method includes: constructing a two-dimensional model of the target mountain; determining the sliding surface of the two-dimensional model; dividing the two-dimensional model into multiple sliding body elements based on the sliding surface; constructing a permissible sliding velocity vector field for the two-dimensional model; calculating the external force power and internal energy dissipation of the two-dimensional model based on the permissible sliding velocity vector field and the internal structural surface strength parameters of the two-dimensional model after freeze-thaw cycle degradation; and predicting the strong seismic stability of the target mountain based on the external force power and the internal energy dissipation. This method solves the problem that existing limit analysis upper bound methods generally do not fully consider the synergistic effect of freeze-thaw cycles and fissure water seepage, leading to difficulties in accurately predicting the strong seismic stability of high mountains.