CN-121738162-B - Karst area pile foundation intelligent positioning and accurate construction method

CN121738162BCN 121738162 BCN121738162 BCN 121738162BCN-121738162-B

Abstract

The invention relates to the technical field of geotechnical engineering and underground hidden engineering construction, and discloses an intelligent positioning and accurate construction method of pile foundations in karst areas, which comprises the steps of establishing a drilling string dynamics model and inverting the mechanical impedance and the mechanical equivalent aperture of the bottom of a drill bit; the method comprises the steps of generating a preset hydraulic impedance boundary model based on mechanical parameter mapping, analyzing actual measurement equivalent flow resistance in a pouring stage and reversely pushing effective hydraulic aperture, calculating flow resistance deviation and aperture deviation of actual measurement parameters and a reference model, identifying geological defect types such as lateral communication karst cave, plastic shrinkage and hole wall collapse according to deviation combination, and generating corresponding self-adaptive control instructions. According to the invention, by converting drilling mechanical characteristics into the perfusion rheological standard and utilizing double deviation analysis of mechanical and hydraulic apertures, the accurate identification of hidden karst defects and closed-loop self-adaptive control of the construction process are realized, and pile forming quality and construction safety under complex karst geological environment are ensured.

Inventors

Wang Maiji
DING GUOAN
GUAN ZHONG
ZHENG XUESHENG
FAN DAJUN

Assignees

浙江省地矿建设有限公司
浙江省地矿勘察院有限公司

Dates

Publication Date: 20260512
Application Date: 20260227

Claims (10)

1. The intelligent positioning and accurate construction method for the pile foundation in the karst area is characterized by comprising the following steps of: s100, establishing a discretization dynamics model for describing frequency domain response characteristics of a drill string system of a drilling machine, and correcting boundary parameters of the dynamics model through an idle running test; S200, collecting vibration and force signals at the top end of a drill string, decoupling and inverting by utilizing the dynamic model to obtain real response of the bottom of the drill bit, calculating transient mechanical impedance of the contact surface of the drill bit and rock, extracting a mechanical damping coefficient, calculating a mechanical specific energy dissipation value according to drilling mechanical parameters, and reconstructing a mechanical equivalent aperture along the depth; s300, establishing a mapping relation between mechanical parameters and hydraulic parameters, predicting the permeability of a rock-soil body according to the mechanical damping coefficient and the mechanical specific energy dissipation value, and generating a reference pressure flow characteristic curve which varies with depth by combining the mechanical equivalent aperture; S400, applying a pulsating pressure wave in the fluid filling process, collecting pipe orifice pressure and flow data to construct a pressure flow hysteresis loop, analyzing to obtain actual measurement equivalent flow resistance, and reversely pushing the current effective hydraulic aperture by utilizing the pressure wave propagation characteristic; S500, calculating flow resistance deviation between actually measured equivalent flow resistance and reference flow resistance corresponding to the reference pressure flow characteristic curve and aperture deviation between mechanical equivalent aperture and effective hydraulic aperture, identifying the current geological defect type from lateral communication karst cave, plastic shrinkage and hole wall collapse or pipeline blockage based on the combination relation between numerical value positive and negative of the flow resistance deviation and the aperture deviation and a threshold range, and generating a corresponding self-adaptive control instruction according to the identification result to adjust the operation mode of the perfusion equipment.
2. The intelligent positioning and accurate construction method for pile foundations in karst areas according to claim 1, wherein the step S100 specifically comprises: dividing a drill string system into a plurality of finite element nodes along the axial direction, establishing a unit transfer matrix describing the frequency domain transformation relation between the top state and the bottom state of a drill rod unit by utilizing a one-dimensional wave equation, and constructing an integral drill string state transfer matrix through matrix cascading; And carrying out iterative correction on the equivalent stiffness coefficient and the equivalent damping coefficient of the top boundary of the integral drill string state transfer matrix by taking the residual error of the minimized theoretical natural frequency and the actual measured natural frequency as a target.
3. The intelligent positioning and accurate construction method for pile foundations in karst areas according to claim 2, wherein the step S200 specifically comprises: calculating the acquired frequency domain signal at the top end of the drill string by utilizing the inverse matrix of the integral drill string state transfer matrix, eliminating the elastic effect of the drill rod, and calculating the real displacement data and the real acting force data of the bottom of the drill bit; calculating the ratio of the vibration speed corresponding to the real acting force data and the real displacement data in the frequency domain to obtain a transient mechanical impedance spectrum; And fitting the transient mechanical impedance spectrum by adopting a rheological model with a linear spring and a linear damper connected in parallel, and extracting equivalent transient stiffness reflecting the elastic modulus of the rock and a mechanical damping coefficient reflecting the breaking crack degree of the rock.
4. The intelligent positioning and accurate construction method for pile foundations in karst areas according to claim 1, wherein in the step S200, the step of reconstructing the mechanical equivalent aperture along the depth specifically comprises: Calculating a mechanical specific energy dissipation value required by breaking a unit volume of rock according to the actual torque at the bottom of the well, the rotating speed of a drill rod, the actual weight on the bottom of the well and the mechanical drilling speed in the drilling process; And when the mechanical specific energy dissipation value is lower than the standard specific energy threshold value, judging that the risk of expanding the diameter exists, and calculating the mechanical equivalent aperture larger than the nominal diameter of the drill bit according to the difference ratio of the mechanical specific energy dissipation value and the standard specific energy threshold value of the bedrock.
5. The intelligent positioning and accurate construction method for pile foundations in karst areas according to claim 1, wherein the step S300 specifically comprises: Constructing a nonlinear mapping function, wherein the estimated permeability of the rock-soil body and the mechanical damping coefficient are in positive correlation and in negative correlation with the mechanical specific energy dissipation value; Calculating a reference flow resistance which should be theoretically possessed according to the estimated permeability and the mechanical equivalent aperture by using a radial flow hydrodynamic model; And generating a reference pressure flow characteristic curve describing the dynamic relation between the perfusion pressure and the perfusion flow under the ideal working condition based on the reference flow resistance and the reference volume stiffness.
6. The intelligent positioning and accurate construction method for pile foundations in karst areas according to claim 1, wherein in the step S400, analyzing to obtain actual equivalent flow resistance specifically comprises: Establishing an unsteady rheological dynamics equation comprising a fluid inertia term, a flow resistance term and a system volume stiffness term; And a pressure flow hysteresis loop constructed based on pressure and flow data acquired in real time is used for solving the unsteady rheological dynamics equation through regression analysis, and the actual measurement equivalent flow resistance capable of representing the actual permeability characteristic of the current stratum is extracted.
7. The intelligent positioning and accurate construction method for pile foundations in karst areas according to claim 6, wherein in the step S400, the current effective hydraulic aperture is reversely pushed by using pressure wave propagation characteristics, and the method specifically comprises the following steps: Performing correlation analysis on the collected pressure signals, identifying the propagation time delay of pressure waves in the underground fluid, and calculating the actual propagation speed; Based on a wave velocity theoretical model, establishing an association relation between an actual propagation velocity and fluid bulk modulus, surrounding rock elastic modulus and flow passage section size, wherein the association relation shows that the wave velocity is reduced along with the increase of lateral constraint stiffness; And (3) reversely solving by using the actual propagation speed to obtain the effective hydraulic aperture under the action of fluid pressure.
8. The intelligent positioning and accurate construction method for pile foundations in karst areas according to claim 1, wherein in the step S500, identifying the current geological defect type from the laterally communicated karst cave comprises: when the measured equivalent flow resistance is monitored to be lower than the reference flow resistance and the flow resistance deviation exceeds a first threshold value, and the mechanical specific energy dissipation value is in a normal bedrock range, judging that a hidden karst cave which is not touched by the drilling tool but is laterally communicated with the hole wall exists; The control system generates instructions, adjusts the pouring equipment to be switched to an intermittent grouting mode, and increases the mixing proportion of the accelerator or the flocculant.
9. The intelligent positioning and accurate construction method for pile foundations in karst areas according to claim 1, wherein in the step S500, identifying the current geological defect type from the plastic shrinkage comprises: when the effective hydraulic aperture is monitored to be smaller than the mechanical equivalent aperture and the aperture deviation exceeds a second threshold value, and the measured equivalent flow resistance is higher than the reference flow resistance, determining that the shrinkage caused by stratum elastic rebound or plastic extrusion occurs; the control system generates an instruction, controls the perfusion equipment to increase the pumping static pressure to a target pressure value, and expands the diameter-reduced area by utilizing the hydrostatic pressure.
10. The intelligent positioning and accurate construction method for pile foundations in karst areas according to claim 1, wherein in the step S500, identifying the current geological defect type from hole wall collapse or pipeline blockage comprises: when the measured equivalent flow resistance is higher than the reference flow resistance and the flow resistance deviation exceeds a third threshold value and the deviation amplitude is larger than the deviation caused by diameter shrinkage, judging that hole wall collapse or pipeline blockage occurs; the control system generates instructions to pause continuous pumping and start a high-frequency pressure pulse oscillation program, and the water hammer energy is utilized for dredging.

Description

Karst area pile foundation intelligent positioning and accurate construction method Technical Field The invention relates to the technical field of geotechnical engineering and underground hidden engineering construction, in particular to an intelligent positioning and accurate construction method for pile foundations in karst areas. Background The geological structure of the karst area has high heterogeneity and anisotropy, and the existence of underground karst cave, fissure development zone and weak fillers can lead deep hole pile foundation construction to face the technical problems of uncontrollable pore forming geometric form, pouring medium loss and the like. The realization of the fine monitoring and closed-loop control of the construction process is a key for guaranteeing the structural integrity of the pile foundation. Existing pile foundation construction monitoring techniques typically consider drilling into holes and fluid injection as two independent operational links. In the drilling stage, the measurement while drilling technology mainly collects mechanical parameters such as weight on bit, torque, rotating speed and the like through a ground surface detection unit, and is used for identifying lithology interfaces or optimizing mechanical efficiency. However, when the existing method is used for processing a deep hole long drill string system, a simplified concentrated parameter model or rigid body assumption is often adopted, delay, attenuation and dispersion effects generated by the propagation of stress waves in an elongated drilling tool are ignored, and deviation exists between true well bottom acting force and displacement response obtained through inversion. In addition, the prior art only focuses on macroscopic mechanical strength characterization of the rock, and does not establish a physical mapping relation between mechanical energy dissipation characteristics in the rock breaking process and hydraulic properties such as stratum pore structure, permeability and the like, so that geological information acquired in the drilling stage cannot be effectively transmitted to the pouring stage. In the pouring stage, the construction control is mainly based on pumping pressure and flow data acquired in real time, and the pumping pressure and flow data are compared with a preset experience threshold value to judge the pouring state. This single fluid monitoring mode has difficulty resolving the physical cause of the anomaly data due to the lack of theoretical rheological benchmarks for the current particular pile hole geologic features. Fluctuations in fluid pressure or flow may be caused by a variety of distinct geological defects, such as non-linear decay of the injection pressure, both from slurry leakage caused by lateral concealed karst cave and from plastic expansion of the weak formation after compression. Under the condition that the geometric dimension of the drilled hole and the prior information of the stratum permeability are lost as references, the monitoring system cannot accurately distinguish the working conditions with different properties such as the lateral communication karst cave, the stratum elastic rebound diameter shrinkage, the collapse and blockage of the hole wall and the like, and further, the grouting adjustment or pressure control measures with pertinence are difficult to match, and the accuracy of pile foundation construction quality control under complex geological conditions is limited. Disclosure of Invention Aiming at the defects of the prior art, the invention provides an intelligent positioning and accurate construction method for pile foundations in karst areas, and solves the problems that geological defects such as lateral hidden karst cave, plastic shrinkage and hole wall collapse are difficult to accurately distinguish and targeted control is implemented due to cutting of drilling mechanical characteristics and pouring rheological behavior data in pile foundation construction in karst areas. The intelligent positioning and accurate construction method for the pile foundation in the karst region mainly comprises the following steps of firstly establishing a discretization dynamics model describing the frequency domain response characteristic of a drilling string system of a drilling machine, correcting boundary parameters of the dynamics model through no-load operation test, secondly collecting vibration and force signals of the top end of the drilling string, obtaining real response of the bottom of the drilling bit through decoupling inversion of the dynamics model, calculating transient mechanical impedance of a contact surface of the drilling bit and rock, extracting a mechanical damping coefficient, calculating a mechanical specific energy dissipation value according to drilling mechanical parameters, reconstructing a mechanical equivalent aperture along the depth, then establishing a mapping relation between the mechanical parameters and the h