Energy-based composite foundation reinforcement effect evaluation method

Abstract

The application discloses a kind of based on energy composite foundation reinforcement effect evaluation method.Method includes the working parameter of construction equipment and the vibration signal of site generated by construction during foundation treatment construction, input energy of construction equipment to site soil is obtained using construction equipment working parameter, wave energy output by site during construction is obtained using site vibration signal, and then absorption energy of site soil during construction is obtained;The relationship between soil absorption energy and soil density is calibrated by compression test, and then the relative density of post-construction soil is converted, to judge the reinforcement quality of composite foundation.The application calculates the absorption energy of site soil by vibration monitoring during construction, and then calculates the relative density of post-construction site soil, which is suitable for foundation treatment methods such as dynamic compaction, vibroflotation gravel pile and other methods with seismic source vibration, and can realize quasi-real-time detection and evaluation of the relative density of treated foundation.

Description

Technical Field

[0001] This invention belongs to the field of evaluation of composite foundations in geotechnical engineering, and in particular relates to an energy-based method for evaluating the reinforcement effect of composite foundations. Background Technology

[0002] With the rapid development of my country's economy and society, buildings and structures are becoming increasingly large. Because these large structures often have large loads or are located in areas with high seismic intensity, the natural foundations often cannot meet the requirements for bearing capacity and liquefaction resistance. In such cases, appropriate foundation treatment technologies are needed to improve the physical and mechanical properties of the natural foundations to meet engineering requirements.

[0003] Dynamic compaction and vibro-compaction are typical foundation treatment methods. They use appropriate construction equipment to vibrate and compress the soil of the natural foundation, compacting the loose soil or combining the fill material with the original foundation to form a composite foundation. This improves the bearing capacity of the foundation, reduces foundation settlement, increases foundation stability, and enhances the foundation's resistance to earthquake liquefaction. They are widely used for the reinforcement of soft foundations such as hydropower station dam foundations, port and wharf foundations, petrochemical engineering foundations, and highway and railway foundations.

[0004] During construction, the process by which construction machinery manipulates and alters the state of soil using relevant equipment is essentially a process of doing work on the soil and transferring energy. The change in soil density reflects the amount of effective work done by external forces, that is, the energy absorbed by the soil during this work. Energy is generally considered a state quantity; changes in energy reflect changes in the state of an object, and the energy required for an object to reach a certain state is fixed. For soil, the energy required to reach a certain density is fixed. Moreover, energy, as a scalar quantity, is convenient to calculate and has a wide range of applications.

[0005] According to relevant standards, composite foundations are typically evaluated using penetration tests and static load tests. These methods usually require a certain period after site construction is completed, and the evaluation of foundation treatment effectiveness relies on random sampling. The evaluation results are insufficient to reflect the soil compaction effect during construction and are therefore localized. Therefore, it is necessary to develop a near-real-time, comprehensive method for evaluating the effectiveness of foundation treatment. Summary of the Invention

[0006] To address the problems existing in the background technology and achieve near real-time, full-range evaluation of foundation treatment effects, the present invention aims to provide an energy-based composite foundation reinforcement effect evaluation method. This method calculates the energy absorbed by the foundation throughout the construction process to determine the foundation compaction in real time, providing a basis for judging construction quality.

[0007] The technical solution adopted in this invention is as follows, including the following steps:

[0008] Step S1: First, collect the working parameters of the construction equipment throughout the entire construction process; then, divide the construction into different stages and obtain the energy input of the construction equipment to the site during the key construction stages.

[0009] Step S2: Using the construction equipment as the vibration source, arrange vibration sensors to collect the vibration signals of the vibration source during construction; then, based on the vibration signals, fit to obtain the vibration attenuation curve; then, obtain the output energy of the site through the effectively reinforced area.

[0010] Step S3: Based on the input and output energy of the site, obtain the average absorbed energy of the soil in the site; conduct compression tests on the soil in the site to obtain the relationship curve between the soil absorbed energy and the void ratio, obtain the post-construction compaction of the soil after the composite foundation is reinforced based on the relationship curve, and evaluate the reinforcement effect of the composite foundation based on the post-construction compaction.

[0011] The specific steps of S1 are as follows:

[0012] S11. First, use the control system of the construction equipment to collect the working parameters of the construction equipment for different construction methods throughout the entire construction process;

[0013] In practice, construction methods include, but are not limited to, dynamic compaction and vibro-compaction. For dynamic compaction, key parameters such as the weight of the tamping hammer and the height from which it falls are collected throughout the construction process. For vibro-compaction, key parameters such as the depth of the vibro-compactor, the current, and the power factor are collected throughout the construction process.

[0014] S12. Based on the types of construction methods and the changing characteristics of the working parameters of construction equipment, the entire construction process is divided into different construction stages. Based on engineering experience, key construction stages are selected from all construction stages, and the working parameters of construction equipment within the key construction stages are extracted.

[0015] When using dynamic compaction and vibro-compaction methods, the construction equipment has a reciprocating "lifting-falling" characteristic in space, which can be used to distinguish the various construction stages. Vibro-compaction includes the drilling stage, hole cleaning stage, vibratory pile foundation stage, and casing removal stage, with the vibratory pile foundation stage being selected as the key construction stage. Dynamic compaction includes the site leveling stage, compaction stage, and backfilling and re-compaction stage, with the compaction stage being selected as the key construction stage.

[0016] S13. Obtain the energy input E of construction equipment to the site during key construction phases. in .

[0017] The specific steps of step S2 are as follows:

[0018] S21. Using construction equipment as the vibration source, vibration sensors are arranged in different soil layers of the untreated site, and the vibration signals of the construction equipment are collected in real time during the construction process through the vibration sensors.

[0019] S22. Obtain the vibration signal collected by the vibration sensor under different vibration propagation distances, wherein the vibration propagation distance is the distance between the vibration source and the vibration sensor; process the vibration signal collected under different vibration propagation distances to obtain the fitting relationship curve between vibration velocity and vibration propagation distance in the unprocessed site and use the fitting relationship curve as the vibration attenuation relationship curve;

[0020] Vibration signals can be used to obtain the corresponding vibration velocity. Different vibration propagation distances correspond to different vibration velocities, and thus the relationship between vibration velocity and vibration propagation distance can be obtained. In other words, the vibration velocity attenuation law in the untreated site can be obtained through vibration signals.

[0021] In practice, a single vibration sensor can be placed in each soil layer, or multiple vibration sensors can be placed at different distances. The same construction equipment will move and operate as the construction progresses. When only one vibration sensor is placed, the vibration signals of that sensor and the same construction equipment at different distances can be obtained; when multiple vibration sensors are placed, the vibration signals of these sensors at different distances to the same construction equipment can be obtained.

[0022] S23. Based on the working parameters of the construction equipment, the effective reinforcement area during the construction process is obtained;

[0023] S24: Based on the vibration attenuation curve obtained in step S22, obtain the vibration velocity v of the soil particles at the boundary of the effective reinforcement area, and process it according to the following formula to obtain the site output energy E. out :

[0024]

[0025] Among them, E out S is the output energy of the site. r To effectively reinforce the wavefront area at the regional boundary, E k V is the elastic wave energy of a soil mass; ρ is the saturated density of the soil; V s E represents the wave velocity of the shear wave propagating in the soil; v represents the vibration velocity of the soil particles; t1 and t2 both represent time points, and E... out Specifically, this refers to the output energy of the site during the time period t2-t1; for the dynamic compaction method, the vibration source is considered to propagate in a hemispherical form within the foundation; for the vibro-compaction method, the vibration source is considered to propagate in a spherical form within the foundation.

[0026] In practice, the area radius R can be... sSubstituting the vibration propagation distance into the vibration attenuation curve, we obtain the corresponding vibration velocity, which is the vibration velocity v of the soil particles.

[0027] The specific steps of step S3 are as follows:

[0028] S31: Based on the input energy E obtained in step S13 in and the output energy E obtained in step S24 out The average absorbed energy E of the soil within the effective reinforcement area is obtained by processing it according to the following formula. t :

[0029]

[0030] Among them, E t To effectively reinforce the average energy absorbed by the soil in the area, E in E is the energy input to the site. out E represents the energy output of the site. z For the pile to absorb energy, V r To effectively reinforce the soil volume within the area; for dynamic compaction, the soil volume is a hemispherical volume; for vibro-compaction, the soil volume is a spherical volume; for dynamic compaction, the pile absorbs energy E. z Take 0; For vibro-compaction construction, the energy absorbed by the pile is determined according to the pile / soil energy absorption ratio. For processes involving granular pile filling and compaction, such as vibro-compaction crushed stone piles and compacted sand piles, the energy absorbed by the pile needs to be considered. Soil absorbed energy = input energy - output energy - pile absorbed energy.

[0031] S32: Select the foundation soil of the untreated site as raw material, prepare soil samples and carry out compression tests, obtain the deformation value of the soil sample under each load level and the corresponding void ratio after the deformation stabilizes, and take the cumulative sum of the products of each load level and the corresponding deformation as the soil absorption energy under that load level. Based on the correspondence between load and void ratio and soil absorption energy, establish the relationship curve between soil absorption energy and void ratio, with each soil absorption energy corresponding to a void ratio.

[0032] In practice, the soil absorbs energy E under the nth load. a This refers to the energy absorbed by the soil to achieve the nth porosity level, specifically the energy absorbed by the soil, E. a Expressed using the following formula:

[0033]

[0034] Among them, F j For the j-th load, D j This represents the soil deformation corresponding to the j-th load level.

[0035] S33: Based on the relationship curve between soil absorbed energy and void ratio obtained in step S32, set the average soil absorbed energy obtained in step S31 as the soil absorbed energy in the relationship curve, and take the void ratio corresponding to the relationship curve as the post-construction soil void ratio e corresponding to the average soil absorbed energy. i The post-construction soil density D is obtained by processing the soil void ratio according to the following formula after composite foundation reinforcement. r :

[0036]

[0037] Among them, D r To effectively reinforce the post-construction soil density in the area, e max e is the maximum void ratio of the soil. min e is the minimum void ratio of the soil. i To effectively reinforce the post-construction void ratio of the soil in the area;

[0038] Both the maximum and minimum void ratios of soil can be obtained by conducting triaxial compression tests on soil samples.

[0039] S34: Compare the post-construction soil compaction with the preset relative soil compaction:

[0040] If the soil compaction degree D after construction r If the density is greater than that of the soil relative density, it indicates that the composite foundation reinforcement is qualified.

[0041] Otherwise, it indicates that the composite foundation reinforcement is unqualified.

[0042] According to the classification criteria for relative soil density in the "Code for Geotechnical Investigation" (50021-2001), soil can be divided into three density states: loose, medium-dense, and dense. At the same time, the soil density after construction is compared with the design relative density. If the relative density is greater than the design, it is recorded as qualified; otherwise, it is recorded as unqualified, thus forming the evaluation result of the reinforcement effect.

[0043] The construction methods mentioned include dynamic compaction and vibro-compaction.

[0044] If the dynamic compaction method is used, then the energy input E of the construction equipment to the construction site in step S13 is... in The following formula is used to obtain it:

[0045] E in =m×H×g

[0046] Among them, E inThe value represents the energy input of the tamping hammer onto the soil at the site; m is the mass of the tamping hammer in kg; H is the height the tamping hammer falls in m; and g is the gravitational constant, taken as 9.8 m / s². 2 ;

[0047] If the vibratory compaction method is used, then the energy input E of the construction equipment to the construction site in step S13 is... in The following formula is used to obtain it:

[0048] E in =EE k

[0049] Among them, E in E represents the energy input of the vibratory compactor to the site soil, and E represents the effective work done by the vibratory compactor during construction by consuming electrical energy. k The kinetic energy of the vibratory beater is the effective work done by consuming electrical energy when it is unloaded.

[0050] For dynamic compaction, the energy output of the construction equipment to the site comes directly from the gravitational potential energy of the tamping hammer; for vibro-compaction, the energy input of the construction equipment to the site comes directly from the electrical energy consumed by the vibro-compactor.

[0051] Step S23 specifically involves:

[0052] If the dynamic compaction method is used, the effective reinforcement area radius R during the construction process is... s The following modified Menard empirical formula was used to obtain the following:

[0053]

[0054] Among them, R s Let m be the radius of the effective reinforcement area of ​​the dynamic compaction method with the vibration source as the center, m be the weight of the hammer, H be the falling height of the hammer, and α1 be a given correction coefficient, which is taken as 0.3-0.8.

[0055] If vibro-compaction is used, the effective reinforcement area radius R during the construction process is... s The following formula is used to obtain it:

[0056]

[0057] Among them, R s V is the radius of the effective reinforcement area for vibratory compaction, P is the power of the vibratory compactor, T is the vibration time of the vibratory compactor during construction, and V is the vibration radius of the effective reinforcement area for vibratory compaction. p Let be the velocity of longitudinal wave propagation in the soil, k be an empirical coefficient, taken as 3-5, and a2 be the energy absorption coefficient of the soil, taken as 0.01-0.03 for sand and 0.04-0.1 for clay.

[0058] This invention first collects the working parameters of the construction equipment during construction, calculates the energy input of the construction equipment to the foundation soil during construction; installs vibration monitoring sensors, debugs the vibration signal acquisition system, collects, stores and analyzes the site vibration signals generated during construction, analyzes the effective reinforcement area of ​​construction, calculates the output energy of the site during construction; calculates the energy absorbed by the soil in the effective reinforcement area during construction; conducts indoor compression tests to calibrate the relationship between soil energy absorption and density, calculates the relative compaction of the soil after construction, and detects and judges the quality of composite foundation reinforcement.

[0059] This invention uses construction equipment (such as tampers in dynamic compaction and vibratory compactors in vibro-compaction) as the excitation source for foundation construction. It receives the elastic wave signals from the vibration source in the foundation through a reasonably arranged array of geophones, calculates the elastic wave fluctuation energy of the foundation using known parameters such as geophone amplitude and geophone position, and finally detects the real-time changes in the relative density of the foundation soil during construction by calculating the effective absorbed energy of the foundation and inverting the relative density calculation.

[0060] This invention calculates the energy absorbed by the soil during construction by monitoring vibrations, and then estimates the relative compaction of the soil after construction. It is applicable to foundation treatment methods with seismic sources, such as dynamic compaction and vibro-compaction stone piles, and can achieve near real-time detection and evaluation of the relative compaction of the treated foundation.

[0061] The beneficial effects of this invention are as follows:

[0062] 1. This invention can evaluate the relative compactness of the foundation soil throughout the entire construction process of composite foundations. Compared with the current quality inspection method of local sampling, this invention has the advantages of a larger detection range and a more comprehensive evaluation of the foundation treatment effect.

[0063] 2. By collecting the working parameters of construction equipment and construction vibration signals in real time, this invention can realize the timely calculation of the energy absorbed by the foundation during the construction process, and can evaluate the foundation reinforcement effect at the hourly level, which is more timely than traditional post-construction quality inspection methods.

[0064] 3. This invention is applicable to foundation treatment methods with seismic source excitation, such as dynamic compaction and vibratory stone piles, and can realize real-time detection and evaluation of the relative compaction of the foundation. Attached Figure Description

[0065] Figure 1 This is a flowchart of the technology of this invention;

[0066] Figure 2 This is a schematic diagram of the site conditions during vibro-compaction construction.

[0067] Figure 3 This is a schematic diagram of the site sensor layout;

[0068] Figure 4 This is a schematic diagram of the vibration attenuation law of the site. Detailed Implementation

[0069] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0070] The method of the present invention is as follows: Figure 1 As shown. The following uses vibro-compaction as an example. The main equipment used in vibro-compaction includes a vibratory compactor. The specific implementation process of vibro-compaction is as follows:

[0071] Step S1: First, collect the working parameters of the vibratory compactor during the construction of vibratory crushed stone piles; then, divide the construction into different stages, and take the typical vibratory compaction construction period as the key construction stage, calculate the input energy of the vibratory compactor to the site during the key construction stage; combine the working time and the depth of the vibratory compactor to form the distribution law of the input energy of the vibratory compactor along the depth.

[0072] Step S1 is as follows:

[0073] S11. Using the control system of the vibratory compaction equipment, collect the working parameters of the vibratory compactor throughout the entire process of vibratory compaction of the stone piles. The site conditions during vibratory compaction are as follows: Figure 2 As shown; for the vibro-compaction construction method, the main data collected during the entire construction process include working time, vibro-compaction depth, vibro-compaction current, vibro-compaction voltage, and vibro-compaction power factor.

[0074] S12. Then, based on the changing characteristics of the working parameters of the construction equipment, different construction stages are divided, and based on engineering experience, key construction stages are selected from all construction stages, and the working parameters of the construction equipment in the key construction stages are extracted.

[0075] Based on engineering experience, the different stages of vibratory compaction can generally be distinguished by the change in vibratory compactor depth. These stages include the hole-making stage, the hole-cleaning stage, and the vibratory compaction retention stage, which consists of multiple retention sections. For vibratory compaction, the stage for controlling construction quality is the vibratory compaction retention stage, which can be considered the critical construction stage. The vibratory compactor operating parameters for each retention section within this stage can be extracted based on the vibratory compactor depth and current, according to the following conditions:

[0076]

[0077] Where, d i d is the oscillator depth at the i-th second;i-1 I represents the oscillator depth at the (i-1)th second; i I represents the oscillator current in the i-th second; Δd represents the depth variation constraint; I m It is a dense current;

[0078] When using dynamic compaction and vibro-compaction methods, the construction equipment has a reciprocating "lifting-falling" characteristic in space, which can be used to distinguish the various construction stages.

[0079] S13. Obtain the energy input E of construction equipment to the site during the vibration retention phase. in :

[0080] E in =EE k =(PP k )T

[0081] Among them, E in E represents the energy input of the vibratory compactor to the site soil, and E represents the effective work done by the vibratory compactor during construction by consuming electrical energy. k The kinetic energy of the vibratory beater is the effective work done by consuming electrical energy when it is unloaded.

[0082] P represents the effective power output of the vibratory pulser during vibration; P k T represents the effective work done by the vibratory compactor when it is unloaded; T is the vibration dwell time of the vibratory compactor. The rotational speed of the vibratory compactor remains constant during the unloaded and vibration dwell stages, therefore its kinetic energy is equal. Thus, the energy input to the site by the vibratory compactor during the vibration dwell stage is equal to the electrical energy consumed by the vibratory compactor during its useful work minus the electrical energy consumed by the vibratory compactor during its unloaded state.

[0083] The vibratory beater is driven by a three-phase motor. When the three-phase motor is working, the active power of the vibratory beater can be calculated as follows: Calculation. U i I is the voltage of the oscillator during operation. i This refers to the current of the oscillator during operation. The power factor of the vibratory oscillator is generally considered to be the operating voltage and power factor of the vibratory oscillator, while only the current changes. Therefore, when calculating the active power of the vibratory oscillator in different operating stages, only the change in current needs to be considered.

[0084] For vibro-compaction construction, the energy input to the site by the construction equipment comes directly from the electrical energy consumed by the vibro-compaction device.

[0085] S14: The distribution law of input energy of oscillator along the depth can be obtained further based on the oscillator depth and input energy of the corresponding time period.

[0086] Step S2: Using a vibratory compactor as the vibration source, arrange vibration sensors to collect vibration signals from the vibration source during the vibratory compaction of the stone pile construction process; then, based on the vibration signals, fit and obtain the vibration attenuation curve; and finally, obtain the output energy of the site through the effective reinforcement area.

[0087] Step S2 is as follows:

[0088] S21. During the construction of vibratory compaction stone piles, a vibratory compactor is used as the vibration source. A vibration sensor is placed in each of the different soil layers along a radial direction of the pile in the untreated site. The vibration signals of each construction device are acquired through these sensors throughout the construction process. The sensor arrangement is as follows: Figure 3 As shown;

[0089] S22. Obtain vibration signals from four sets of vibration sensors collected by the vibration sensor at different vibration propagation distances. The vibration propagation distance is specifically the distance between the vibration source and the corresponding vibration sensor. Process the vibration signals collected at different vibration propagation distances to obtain the fitting curve of vibration velocity versus vibration propagation distance in the unprocessed site, and use it as the vibration attenuation curve. Figure 4 As shown;

[0090] Vibration signals can be used to obtain the corresponding vibration velocity. Different vibration propagation distances correspond to different vibration velocities, and thus the relationship between vibration velocity and vibration propagation distance can be obtained. In other words, the vibration velocity attenuation law in the untreated site can be obtained through vibration signals.

[0091] S23. Based on the operating parameters of the construction equipment, obtain the effective reinforcement area during the construction process:

[0092]

[0093] Among them, R s V represents the radius of the effective reinforcement area of ​​the vibratory compaction method, centered on the vibration source, in meters (m); P is the power of the vibratory compactor, in watts (W); T is the vibration dwell time of the vibratory compactor during construction, in seconds (s); V p denoted as ρ, where ρ is the velocity of longitudinal waves propagating in the soil, in m / s; k is an empirical coefficient, taken as 3-5; a2 is the energy absorption coefficient of the soil, taken as 0.01-0.03 for sand and 0.04-0.1 for clay.

[0094] S24: During vibro-compaction construction, the vibration source is considered as a point source. The vibration wave propagates in the foundation in a spherical form. Based on the vibration attenuation curve obtained in step S22, the vibration velocity v of the soil particles at the boundary of the effective reinforcement area is obtained, and the output energy of the site is obtained by processing it according to the following formula:

[0095]

[0096] S r =8πR 2

[0097] Among them, E out S is the output energy of the site. r To effectively reinforce the wavefront area at the regional boundary, E k V is the elastic wave energy of a soil mass; ρ is the saturated density of the soil; V s E represents the wave velocity of the shear wave propagating in the soil; v represents the vibration velocity of the soil particles; t1 and t2 both represent time points, and E... out Specifically, this refers to the output energy of the site during the time period t2-t1; for the vibro-compaction method, the vibration source is considered to propagate in the form of a sphere within the foundation.

[0098] In practical implementation, the effective area radius R can be... s Substituting the vibration propagation distance into the vibration attenuation curve, we obtain the corresponding vibration velocity, which is the vibration velocity v of the soil particles.

[0099] S25: The distribution law of the output energy of the vibrator along the depth can be obtained further based on the vibrator depth and output energy of the corresponding time period;

[0100] Step S3: Calculate the energy absorbed by the soil in the site based on the input and output energy of the site, and calculate the average energy absorbed by the soil within the effective reinforcement area. Conduct compression tests on the soil in the site to obtain the relationship curve between the soil's energy absorption and void ratio. Obtain the post-construction compaction of the soil after composite foundation reinforcement based on the relationship curve, and evaluate the reinforcement effect of the composite foundation based on the post-construction compaction.

[0101] Step S3 is as follows:

[0102] S31: Based on the input energy E obtained in step S13 in and the output energy E obtained in step S24 out The average energy absorbed by the soil within the effective reinforcement area is obtained by processing it according to the following formula:

[0103]

[0104] Among them, E t To effectively reinforce the average energy absorbed by the soil in the area, E in E is the energy input to the site. out E represents the energy output of the site. z To absorb energy from the pile, take 0.5E. in V rTo effectively reinforce the soil volume within the area; for vibro-compaction construction, the soil volume is the volume of a sphere; for vibro-compaction construction, the energy absorbed by the pile is determined according to the pile / soil energy absorption ratio. For processes involving granular pile filling and compaction, such as vibro-compaction stone piles and compacted sand piles, the energy absorbed by the pile needs to be considered. Soil absorbed energy = input energy - output energy - pile absorbed energy

[0105] S32: Select the foundation soil of the untreated site as raw material, prepare soil samples and carry out compression tests, obtain the deformation value of the soil sample under each load and the corresponding void ratio after the deformation stabilizes, and take the cumulative sum of the products of each load and the corresponding deformation as the soil absorbed energy under that load. Based on the correspondence between load and void ratio and volume absorbed energy, establish the relationship curve between soil absorbed energy and void ratio, with each soil absorbed energy corresponding to a void ratio.

[0106] In practice, the soil absorbs energy E under the nth load. a This refers to the energy absorbed by the soil to achieve the nth porosity level, specifically the energy absorbed by the soil, E. a Expressed using the following formula:

[0107]

[0108] Among them, F j For the j-th load, D j This represents the soil deformation corresponding to the j-th load level.

[0109] S33: Based on the relationship curve between soil energy absorption and void ratio obtained in step S32, set the average soil energy absorption obtained in step S31 as the soil energy absorption in the relationship curve, and take the void ratio corresponding to the relationship curve as the post-construction soil void ratio corresponding to the average soil energy absorption. Then, based on the post-construction soil void ratio, calculate the post-construction soil density using the following formula:

[0110]

[0111] Among them, D r To effectively reinforce the relative density of the soil in the area, e max e is the maximum void ratio of the soil. min e is the minimum void ratio of the soil. i To effectively reinforce the post-construction void ratio of the soil in the area;

[0112] Both the maximum and minimum void ratios of the soil can be obtained by conducting triaxial compression tests on soil samples. Since a compression test was performed on the soil in step S32, the post-construction soil density D obtained in step S33 is therefore... r This refers to the soil density after composite foundation reinforcement.

[0113] S34: Compare the post-construction soil compaction with the preset relative soil compaction:

[0114] If the soil density after construction is greater than the relative density of the soil, it indicates that the composite foundation reinforcement is qualified.

[0115] Otherwise, it indicates that the composite foundation reinforcement is unqualified.

[0116] According to the classification criteria for relative soil density in the "Code for Geotechnical Investigation" (50021-2001), soil can be divided into three density states: loose, medium-dense, and dense. At the same time, the soil density after construction is compared with the design relative density. If the relative density is greater than the design, it is recorded as qualified; otherwise, it is recorded as unqualified, thus forming the evaluation result of the reinforcement effect.

[0117] In a specific embodiment, a foundation needs to be treated with vibro-compaction crushed stone piles. The expected depth of the treatment area is 26m. The soil in the treatment area, from shallow to deep, consists of ① a layer of drifting sand and gravel and ② a layer of silty clay, with soil thicknesses of 12m and 18m respectively. The crushed stone piles are designed with a diameter of 1.2m and are arranged in a triangular pattern.

[0118] The first step involves placing two 15-1000Hz triaxial accelerometers at a distance of 12m from the construction crushed stone piles in the untreated foundation at depths of 6m and 15m below the ground surface, and configuring a corresponding vibration signal acquisition system, such as... Figure 3 As shown.

[0119] The second step involves collecting the vibratory compactor's operating parameters and collecting site vibration signals through a vibration signal acquisition system during the vibratory compaction of stone piles.

[0120] The third step is to determine the working parameters of the vibratory compactor and the site vibration signals for different construction stages based on engineering experience.

[0121] The fourth step is to calculate the input energy of the vibratory compactor to different depths of the site based on the working parameters of the vibratory compactor, and to calculate the output energy of the site at different depths based on the site vibration signal, thereby obtaining the energy absorbed by the soil at different depths of the site.

[0122] The fifth step is to take undisturbed soil samples, with 3-4 samples taken from each soil layer, and conduct compression tests. Based on the test results, determine the relationship between the soil void ratio and absorbed energy. The relationship between void ratio and absorbed energy varies for different soil types.

[0123] The sixth step involves substituting the energy absorbed by the soil at different depths into the corresponding functional relationship between the soil void ratio and the absorbed energy, calculating the void ratio of the soil at different depths after construction and converting it into soil density, then comparing it with the designed soil density to form an evaluation report on the effect of vibratory compaction.

Claims

1. A method for evaluating the effectiveness of energy-based composite foundation reinforcement, characterized in that, Includes the following steps: Step S1: First, collect the working parameters of the construction equipment throughout the entire construction process; then, divide the construction into different stages and obtain the energy input of the construction equipment to the site during the key construction stages. Step S2: Using the construction equipment as the vibration source, arrange vibration sensors to collect the vibration signals of the vibration source during construction; then, based on the vibration signals, fit to obtain the vibration attenuation curve; then, obtain the output energy of the site through the effectively reinforced area. Step S3: Based on the input and output energy of the site, obtain the average absorbed energy of the soil in the site; conduct compression tests on the soil in the site to obtain the relationship curve between the soil absorbed energy and the void ratio, obtain the post-construction compaction of the soil after the composite foundation is reinforced based on the relationship curve, and evaluate the reinforcement effect of the composite foundation based on the post-construction compaction. The specific steps of S1 are as follows: S11. First, use the control system of the construction equipment to collect the working parameters of the construction equipment for different construction methods throughout the entire construction process; S12. Then, based on the changing characteristics of the working parameters of the construction equipment, different construction stages are divided, and key construction stages are selected from all construction stages. The working parameters of the construction equipment in the key construction stages are extracted. S13. Obtain the energy input to the site from construction equipment during key construction phases. ; The specific steps of step S2 are as follows: S21. Using construction equipment as the vibration source, vibration sensors are arranged in different soil layers of the untreated site, and the vibration signals of the construction equipment are collected in real time during the construction process through the vibration sensors. S22. Obtain the vibration signal collected by the vibration sensor under different vibration propagation distances, wherein the vibration propagation distance is the distance between the vibration source and the vibration sensor; process the vibration signal collected under different vibration propagation distances to obtain the fitting relationship curve between vibration velocity and vibration propagation distance in the unprocessed site and use it as the vibration attenuation relationship curve; S23. Based on the working parameters of the construction equipment, the effective reinforcement area during the construction process is obtained; S24: Based on the vibration attenuation curve obtained in step S22, obtain the vibration velocity v of the soil particles at the boundary of the effective reinforcement area, and process it according to the following formula to obtain the output energy of the site: in, For the energy output of the site, To effectively reinforce the wavefront area at the regional boundary, V is the elastic wave energy of a soil mass; ρ is the saturated density of the soil; V s ν is the wave velocity of the shear wave propagating in the soil; v is the vibration velocity of the soil particles.

2. The method for evaluating the effect of energy-based composite foundation reinforcement according to claim 1, characterized in that: The specific steps of step S3 are as follows: S31: Based on input energy and output energy The average energy absorbed by the soil within the effective reinforcement area is obtained by processing it according to the following formula: in, To effectively reinforce the average energy absorption of the soil in the area, The energy input to the site, For the energy output of the site, For the pile to absorb energy, To effectively reinforce the spatial volume of the soil within the area; S32: Select the foundation soil of the untreated site as raw material, prepare soil samples and carry out compression tests, obtain the deformation value of the soil sample under each load level and the corresponding void ratio after the deformation stabilizes, take the cumulative sum of the product of each load level and the corresponding deformation as the soil absorption energy under that load level, and establish the relationship curve between soil absorption energy and void ratio. S33: Based on the relationship curve between soil energy absorption and void ratio, the average soil energy absorption is set as the soil energy absorption in the relationship curve, and the void ratio corresponding to the relationship curve is taken as the post-construction soil void ratio. The post-construction soil density after composite foundation reinforcement is obtained by processing the soil void ratio according to the following formula. : in, To effectively reinforce the relative density of the soil in the area, This represents the maximum void ratio of the soil. This represents the minimum void ratio of the soil. To effectively reinforce the post-construction void ratio of the soil in the area; S34: Compare the post-construction soil compaction with the preset relative soil compaction: If the soil compaction after construction If the density is greater than that of the soil relative density, it indicates that the composite foundation reinforcement is qualified. Otherwise, it indicates that the composite foundation reinforcement is unqualified.

3. The method for evaluating the effect of energy-based composite foundation reinforcement according to claim 1, characterized in that: The construction methods mentioned include dynamic compaction and vibro-compaction. If the dynamic compaction method is used, then the energy input of the construction equipment to the construction site in step S13 is... The following formula is used to obtain it: in, Let m be the energy input of the rammer onto the soil at the site, and m be the mass of the rammer. The height to which the hammer falls. It is the gravitational constant; If vibro-compaction is used, then the energy input of the construction equipment to the construction site in step S13 is... The following formula is used to obtain it: in, This refers to the energy input of the vibratory compactor onto the site soil. The effective work done by the vibratory compactor to consume electrical energy during construction. This is the kinetic energy of the vibratory impactor.

4. The method for evaluating the effect of energy-based composite foundation reinforcement according to claim 1, characterized in that: Step S23 specifically involves: If the dynamic compaction method is used, the effective reinforcement area radius during the construction process is... The following formula is used to obtain the result: in, The radius of the effective reinforcement area for the dynamic compaction method is given by m, where m is the weight of the tamping hammer and H is the drop height of the tamping hammer. For the given correction factor; If vibro-compaction is used, the effective reinforcement area radius during construction is... The following formula is used to obtain the result: in, P represents the radius of the effective reinforcement area for vibratory compaction, P is the power of the vibratory compactor, and T is the vibration time of the vibratory compactor during construction. Let k be the velocity of the longitudinal wave propagating in the soil, and k be an empirical coefficient. This is the energy absorption coefficient of the soil.

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