A monitoring system and method for the stability of water-sensitive soft soil highway engineering

Abstract

The present application discloses a monitoring system and method for the stability of water-sensitive soft soil highway projects. It is used to reduce the time spent on roadbed monitoring, improve monitoring efficiency, and reduce the impact on the construction process. The present application includes a monitoring frame, an oscilloscope, a signal generator, and a terminal; the monitoring frame is set in a water-sensitive soft soil roadbed, and 4 bending element assemblies are set on the monitoring frame, and the 4 bending element assemblies are all connected to the oscilloscope, wherein two adjacent bending element assemblies are connected to the signal generator; the terminal is connected to the signal generator and the oscilloscope respectively; thereby controlling the signal generator to transmit a signal to the bending element assembly, the bending element assembly is used to generate a shear wave through the signal and display it on the oscilloscope, and the terminal is used to monitor the water-sensitive soft soil roadbed through the shear wave.

Description

Technical Field

[0001] The present application relates to the field of highway subgrade monitoring, and in particular to a system and method for monitoring the stability of sensitive soft soil highway projects. Background Art

[0002] Water-sensitive soft soil is an unsaturated, structurally unstable clay soil with significant swelling and shrinkage, overconsolidation, and multiple fissures. This poses a significant threat to highway construction, often causing serious pavement problems such as subsidence and cracking. These conditions severely impact the durability of the pavement structure and driving safety, leading to significant highway maintenance and repair costs. Current highway regulations stipulate that water-sensitive soft soil should not be used directly for roadbed filling. It must undergo appropriate treatment before use, and the total swelling and shrinkage rate of the treated water-sensitive soft soil must not exceed 0.7%. Common chemical treatment materials for water-sensitive soft soil include lime, fly ash, cement, chemical stabilizers, and gravel.

[0003] Research shows that more than 70% of the permanent deformation of the road surface that causes highway diseases comes from the contribution of the roadbed deformation. Therefore, when using improved water-sensitive soft soil to fill the roadbed, monitoring the road surface deformation and whether the roadbed stiffness is stable over a long period of time are important indicators for evaluating the treatment quality of water-sensitive soft soil. max It reflects the ability of water-sensitive soft soil to resist deformation and is an important parameter for evaluating the quality of water-sensitive soft soil roadbeds. Existing technologies often use traditional surveying and mapping, ground photography, and laboratory testing to monitor roadbed stability and assess roadbed quality.

[0004] However, since the construction schedule of most highway projects is very tight and decisions need to be made quickly, the existing roadbed monitoring methods take a long time, resulting in low efficiency of roadbed monitoring and affecting the construction progress. Summary of the Invention

[0005] In order to solve the above technical problems, the present application provides a monitoring system and method for the stability of sensitive soft soil highway projects, which reduces the time spent on roadbed monitoring, improves the efficiency of roadbed monitoring, and reduces the impact on the construction process.

[0006] The first aspect of the present application provides a monitoring system for the stability of sensitive soft soil highway engineering, comprising:

[0007] Monitoring frame, oscilloscope, signal generator and terminal;

[0008] The monitoring frame is set in the water-sensitive soft soil roadbed, and four bending element assemblies are set on the monitoring frame. The four bending element assemblies are all connected to the oscilloscope, and two adjacent bending element assemblies are connected to the signal generator;

[0009] The terminal is connected to the signal generator and the oscilloscope respectively; thereby controlling the signal generator to transmit a signal to the bending element assembly, the bending element assembly is used to generate shear waves through the signal and display them on the oscilloscope, and the terminal is used to monitor the water-sensitive soft soil roadbed through the shear waves.

[0010] Optionally, a device socket is provided at the connection between the monitoring frame and the bending element assembly, the device socket is embedded in the monitoring frame, and the bending element assembly is connected to the device socket and protrudes inwardly from the inner wall of the monitoring frame.

[0011] Optionally, the monitoring frame further includes a rubber plug, which is located beside the device socket and connected to the monitoring frame, and is used to plug the device socket.

[0012] Optionally, the device socket includes a device slot and a gasket;

[0013] The gasket is located at the bottom of the device slot and is flush with the inner wall of the monitoring frame. A rubber membrane is provided in the gasket. A gap is provided between the rubber membrane and the gasket. The bending element assembly is fixed in the device slot through the gap.

[0014] Optionally, the gasket is made of stainless steel;

[0015] and / or;

[0016] The device slot is made of chlorinated polyethylene.

[0017] Optionally, the width of the gap is 10-14 mm.

[0018] Optionally, the bending element assembly includes a bending element, a cable connector and a device base;

[0019] The device base is connected to the monitoring frame, and the bending element is fixed on the device base and connected to the cable connector.

[0020] Optionally, the monitoring frame is made of stainless steel.

[0021] Optionally, two adjacent bending element assemblies are perpendicular to each other.

[0022] Optionally, a cutter is provided at the bottom of the monitoring frame, and the cutter is used to fix the test frame on the water-sensitive soft soil roadbed.

[0023] The second aspect of the present application provides a method for monitoring the stability of a water-sensitive soft soil highway project, comprising:

[0024] Determine the location points to be monitored;

[0025] Setting a test pit at the location point;

[0026] placing a monitoring frame in the test pit;

[0027] Sending a signal to the bending element assembly at a preset interval through a signal generator, so that the bending element assembly generates a shear wave and displays it on an oscilloscope;

[0028] Calculate the small strain stiffness G of water-sensitive soft subgrade soil based on the shear wave displayed in the oscilloscope max And the lateral limit modulus M0, so according to the small strain stiffness G max And the lateral limit modulus M0 is used to monitor the water-sensitive soft roadbed soil.

[0029] Optionally, the small strain stiffness G of the water-sensitive soft roadbed soil is calculated based on the shear wave displayed in the oscilloscope. max And the lateral limit modulus M0 includes:

[0030] Determine the propagation speed of the P shear wave and the S shear wave between the two bending element components respectively, and obtain Vs and V P ;

[0031] The small strain stiffness G is calculated according to the following formula max And lateral limit modulus M0:

[0032]

[0033]

[0034] Where ρ is the dry density of water-sensitive soft subgrade soil.

[0035] It can be seen from the above technical solutions that this application has the following effects:

[0036] 1. Based on the expansion characteristics and small strain characteristics of water-sensitive soft roadbed soil, this application has the advantages of low cost, simple and fast operation, and non-destructive testing. It can be deployed on a large scale, monitor for a long time, save testing costs, and has good economic benefits and engineering prospects.

[0037] 2. This application uses bending element components to perform small strain stiffness G maxThe bending element testing technology used in the bending element assembly has the characteristics of non-destructive testing, can ensure the reliability of the monitoring results, can be reused, and has a long service life.

[0038] 3. This application uses the small strain stiffness G max The relationship between the lateral limit modulus M0 and the shear wave is measured. By measuring the propagation characteristics of the shear wave in the water-sensitive soft soil roadbed, the small strain stiffness G of the water-sensitive soft soil roadbed is calculated. max and lateral limit modulus M0, which has the advantages of short monitoring time and can improve monitoring efficiency, thereby avoiding the impact of the monitoring process on the construction progress. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in this application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 A schematic diagram of a monitoring system for the stability of a water-sensitive soft soil highway project in this application;

[0041] Figure 2 A side view schematic diagram of a test frame in a monitoring system for the stability of a water-sensitive soft soil highway project in this application;

[0042] Figure 3 This is a schematic diagram of a device slot in a monitoring system for the stability of a water-sensitive soft soil highway project in this application;

[0043] Figure 4 This is a schematic diagram of a bending element component in a monitoring system for the stability of a water-sensitive soft soil highway project in this application;

[0044] Figure 5 This is a schematic diagram of a bending element in a monitoring system for the stability of a water-sensitive soft soil highway project in this application;

[0045] Figure 6 This is a schematic diagram of a rubber stopper in a monitoring system for the stability of a water-sensitive soft soil highway project in this application;

[0046] Figure 7 A schematic diagram of a method for monitoring the stability of a water-sensitive soft soil highway project in this application;

[0047] Figure 8 This is a schematic diagram of a method for determining the total time from S shear wave excitation to reception by excitation and reception of shear wave signals in this application;

[0048] Figure 9 Schematic diagram of a method for determining the total time from P shear wave excitation to reception by excitation and reception of shear wave signals in this application;

[0049] Figure 10 A schematic diagram of a method for determining system delay time by exciting and receiving shear wave signal diagrams in this application;

[0050] Figure 11 is the small strain stiffness G of water-sensitive soft subgrade soil at the five monitoring points in this application max Schematic diagram of changes over time;

[0051] Figure 12 Schematic diagram of the change of the lateral limit modulus M0 of the water-sensitive soft roadbed soil at the five monitoring points in this application over time;

[0052] Figure 13 Schematic diagram of the change of Poisson's ratio ν of water-sensitive soft roadbed soil over time at five monitoring points in this application;

[0053] Figure 14 Schematic diagram of the change of axial strain ε of water-sensitive soft soil roadbed with time at five monitoring points in this application;

[0054] Figure 15 is the swelling potential ε of water-sensitive soft subgrade soil at the five monitoring points in this application x Schematic diagram of the relationship with the cumulative strain Δε. DETAILED DESCRIPTION

[0055] The present application provides a monitoring system and method for the stability of water-sensitive soft soil highway projects, which are used to reduce the time spent on roadbed monitoring, improve monitoring efficiency, and reduce the impact on the construction process.

[0056] See also Figures 1 to 6 The present application provides a monitoring system for the stability of a water-sensitive soft soil highway project, comprising:

[0057] Monitoring frame 1, oscilloscope 29, signal generator 30 and terminal 31; monitoring frame 1 is set in a water-sensitive soft soil roadbed, and 4 bending element assemblies are set on the monitoring frame 1, and the 4 bending element assemblies are all connected to the oscilloscope 29, among which two adjacent bending element assemblies are connected to the signal generator 30; terminal 31 is respectively connected to the signal generator 30 and the oscilloscope 29; thereby controlling the signal generator 30 to transmit a signal to the bending element assembly, the bending element assembly is used to generate shear waves through signals and display them on the oscilloscope 29, and the terminal 31 is used to monitor the water-sensitive soft soil roadbed through shear waves.

[0058] For ease of description, the two bending element assemblies connected to signal generator 30 are labeled as S-wave exciter 81 and P-wave exciter 82 in this application. Correspondingly, the bending element assembly opposite S-wave exciter 81 is called S-wave receiver 83, and the bending element assembly opposite P-wave exciter 82 is called P-wave receiver 84. Furthermore, signal generator 30 is connected to S-wave exciter 81 and P-wave exciter 82 via data transmission cable 25, which is used to transmit signals. Further description is provided below.

[0059] When the present application is actually used, the monitoring frame 1 is placed in a horizontal state in the position to be monitored of the water-sensitive soft soil roadbed, and a signal is sent to the S-wave exciter 81 and the P-wave exciter 82 through the signal generator 30. The signal is an excitation signal voltage pulse. At this time, under the signal, the S-wave exciter 81 generates a transverse shear wave and transmits it in the direction of the S-wave receiver 83. Similarly, the compression shear wave generated by the P-wave exciter 82 is also transmitted in the direction of the P-wave receiver 84. When the S-wave receiver and the P-wave receiver receive the shear wave, the oscilloscope 29 displays the shear wave, and then the terminal monitors the water-sensitive soft soil roadbed through the shear wave. The detailed monitoring process will be described in the monitoring method of the present application and will not be described here. In this embodiment, in order to facilitate the connection between the signal generator 30 and the S-wave exciter 81 and the P-wave exciter 82, markings can be made on the monitoring frame 1, such as Figure 1 As shown, an “S” symbol 12 and a “P” symbol 13 are marked on the monitoring frame 1 , which facilitates the connection of the oscilloscope 29 and the signal generator 30 in actual use.

[0060] Optionally, two adjacent bending element components are in a perpendicular state to each other, that is, the S-wave exciter 81, the P-wave exciter 82 and the P-wave receiver 84 are all in a vertical state. It can be seen that the P-wave exciter 82 and the P-wave receiver 84 are in a horizontal state of 180 degrees. Similarly, the S-wave exciter 81 and the S-wave receiver 83 are in a horizontal state of 180 degrees. During actual operation, the transmission of the shear waves generated by the S-wave exciter 81 and the P-wave exciter 82 is a linear transmission.

[0061] Optionally, in one achievable manner, the bending element assembly is composed of a bending element 17, a cable plug 23, and a device base 14. The bending element 17 is fixed in the device base 14, the cable plug 23 passes through the device base 14 and is connected to the bending element 17, and the cable connector 23 is fixed on the outside of the device base 14. In practice, the device base 17 is connected to the monitoring frame 1. When connected, the bending element 17 faces the inside of the monitoring frame 1, and the cable connector 23 faces the outside of the monitoring frame 1. The cable connector 23 is used to connect to the signal generator 30 and the oscilloscope 29. In addition, a ground wire 24 extends from the position of the cable connector 23, and the ground wire 24 is used to connect to the ground. In the present application, the device base 14 includes a device cap body 15 and a device column body 16. The device cap body 15 is vertically connected to the device column body 16. The middle of the device column body 16 is hollow, and the bending element 17 is fixed in the device column body 16.

[0062] The bending element 17 is composed of a metal sheet 18, a piezoelectric ceramic 19, a Teflon layer 20, an aluminum layer 21, and an epoxy resin layer 22. A metal sheet 18 is arranged between a pair of piezoelectric ceramics 19, and the piezoelectric ceramics 19 are shielded and protected by an insulating Teflon layer 20 and an aluminum layer 21. The outermost layer is sealed with an epoxy resin layer 22 for waterproofing.

[0063] In this embodiment, the bending element assembly is connected to the monitoring frame 1 and is connected to the signal generator 30 and the oscilloscope 29. The signal generator 30 is used to send signals to the S-wave exciter 81 and the P-wave exciter 82 in the bending element assembly, thereby generating shear waves. The shear waves are received by the S-wave receiver 83 and the P-wave receiver 84 and displayed on the oscilloscope 29. The terminal 31 monitors the water-sensitive soft soil roadbed through the shear waves in the oscilloscope 29. In this way, compared with the traditional roadbed monitoring method, the time spent on roadbed monitoring is reduced, the monitoring efficiency can be improved, and the impact on the construction process can be avoided.

[0064] Secondly, the operation of this application is simple and quick, with high monitoring efficiency;

[0065] In addition, the bending component testing technology has the characteristics of non-destructive monitoring, so it can improve the reliability of the monitoring results, and can be used multiple times with a long service life.

[0066] Optionally, a device socket 3 is provided at the connection between the monitoring frame 1 and the bending element assembly. The device socket 3 is embedded in the monitoring frame 1, and the bending element assembly is connected to the device socket 3 and protrudes inward from the inner wall of the monitoring frame. In practice, when the device socket 3 is embedded in the monitoring frame 1, the device socket 3 is flush with the inner wall of the monitoring frame 1, and when the bending element assembly is connected to the device socket 3, the bending element 17 in the bending element assembly protrudes inward from the inner wall of the monitoring frame 1. In actual use, the interior of the device socket 3 is hollow, and the bending element assembly inserts the bending element 17 into the device socket 3 and fixes it in the device socket 3, wherein the fixing method includes snaps, bolts, etc.

[0067] Optionally, the present application also includes a rubber plug 26, which is disposed adjacent to the device socket 3 and connected to the monitoring frame 1. The rubber plug 26 is used to plug the device socket 3. In this embodiment, four device sockets 3 are provided corresponding to four bending element assemblies, so four rubber plugs 26 are also provided. In practice, the rubber plug 26 can be connected to the monitoring frame 1 via a connecting rope, making the rubber plug 26 movable. When roadbed monitoring is not required, the rubber plug 26 plugs the device socket 3 to protect the device socket 3. When roadbed monitoring is required, the rubber plug 26 is removed, allowing the bending element assembly in the device socket 3 to be connected to the oscilloscope 29 and signal generator 30, thereby performing roadbed monitoring.

[0068] The rubber stopper 26 includes a stopper cap 27 and a stopper body 28 . In actual use, the stopper body 28 extends into the device socket 3 , while the stopper cap 27 is located outside the device socket 3 .

[0069] Optionally, the device socket 3 includes a device slot 4 and a gasket 5. The gasket 5 is arranged at the bottom of the device slot 4 and is flush with the monitoring frame 1. A rubber membrane 6 is arranged in the gasket 5, and the rubber membrane 6 is embedded in the gasket 5. A gap 7 is provided between the rubber membrane 6 and the gasket 5. The bending element assembly is fixed in the device slot 4, and the bending element 17 in the bending element assembly passes through the gap 7 and the inner wall of the monitoring frame 1. In practice, the middle of the device slot 4 is a hollow area, and the hollow area is used to place the bending element assembly. During actual installation, the bending element assembly is inserted from the front end of the device socket 4 along the direction of the gasket 5, and the bending element 17 is aligned with the gap 7. After the bending element 17 passes through the gap 7 and the inner wall of the monitoring frame 1, the bending element assembly is fixed on the monitoring frame 1.

[0070] In this embodiment, by embedding the rubber membrane 6 in the gasket 5 , soil particles can be prevented from entering the device slot 4 from the gasket 5 , thereby preventing the soil particles from damaging the device slot 4 .

[0071] Optionally, in one practicable manner, the material of the gasket 6 is stainless steel;

[0072] and / or;

[0073] The material of the device slot 4 is chlorinated polyethylene.

[0074] Optionally, in another achievable manner of the present application, the width of the gap 7 provided in the middle position between the gasket 5 and the rubber membrane 6 is 10-14 mm, and the gap 7 matches the bending element 17 in the bending element assembly.

[0075] Optionally, the material of the monitoring frame 1 is stainless steel. In practice, the monitoring frame 1 needs to be buried in the soil when in use. The soil contains moisture and some corrosive substances. In order to ensure the long-term use of the monitoring frame 1, the material of the monitoring frame 1 is selected to be stainless steel to improve the service life of the monitoring frame 1.

[0076] Optionally, a cutter 2 is provided at the bottom of the monitoring frame 1. The cutter 2 is conical from top to bottom. The cutter 2 is used to fix the monitoring frame 1 on the water-sensitive soft soil roadbed. In actual use, the bottom of the cutter 2 is sharper. When the monitoring frame 1 is lowered horizontally, the cutter 2 first contacts the roadbed soil, and an external force is applied downward on the monitoring frame 1, so that the cutter 2 is embedded downward in the soil, thereby fixing the monitoring frame 1 on the water-sensitive soft soil roadbed.

[0077] In this embodiment, by providing a conical cutter 2 at the bottom of the monitoring frame 1, the monitoring frame 1 can be fixed, thereby reducing the position change of the monitoring frame 1 when soil is buried above the monitoring frame 1.

[0078] The second aspect of this application provides a method for monitoring the stability of a water-sensitive soft soil highway project. It should be noted that this method can be applied to a terminal, a system, or a server. For example, the terminal can be a smartphone, a computer, a tablet, a smart TV, a smartwatch, a portable computer terminal, or a fixed terminal such as a desktop computer. For ease of explanation, this application uses a system as the execution subject for example.

[0079] See also Figure 7 The present application provides a method for monitoring the stability of a water-sensitive soft soil roadbed, including:

[0080] 101. The system determines the location point to be monitored.

[0081] In this embodiment, the system selects a location point to be monitored on the water-sensitive soft soil roadbed, and the location point is used to place a monitoring frame and perform detection.

[0082] In addition, in order to ensure data accuracy, in this embodiment, four other different road sections are selected on the water-sensitive soft soil roadbed, and one location point to be monitored is selected for each of them, resulting in a total of five location points to be monitored.

[0083] 102. The system sets up a test pit at the location point.

[0084] After determining the locations to be monitored, test pits are excavated at these locations. The shape of the test pits is determined based on the shape of the monitoring frame, and the size of the test pits also matches the monitoring frame. For example, if the monitoring frame is circular, the test pits can be circular or square. In step 101, a total of five locations to be monitored were selected, so a test pit should be excavated at each location.

[0085] 103. The system places the monitoring frame in the test pit.

[0086] When placing the monitoring frame in the test pit, place the monitoring frame horizontally in the test pit and apply external force downward on the monitoring frame so that the cutter on the monitoring frame is embedded downward in the soil of the test pit. At this time, the signal generator, oscilloscope and bending element assembly on the monitoring frame are connected. Then fill the test pit with improved expansive soil and compact it. At the same time, bury a soil strain gauge 1-2 cm above the monitoring frame. The soil strain gauge is also connected to the terminal through a data cable.

[0087] In this application, the improved expansive soil is formed by adding lime, fly ash, cement, chemical stabilizer, gravel and other improvement materials to water-sensitive soft soil.

[0088] When the monitoring frame is embedded in the soil, the soil in the test pit fills the inner side of the monitoring frame. At this time, the bending element on the inner side of the monitoring frame is vertically inserted into the soil with an insertion depth of 5 mm.

[0089] Optionally, in one feasible manner, after the monitoring frame is installed, the monitoring frame is tested. During the testing process, after the terminal controls the signal generator to send a signal, the monitoring frame, oscilloscope, etc. are checked to see whether they are working properly.

[0090] 104. The system sends a signal to the bending element assembly through a signal generator at a preset interval, so that the bending element assembly generates a shear wave and displays it on an oscilloscope.

[0091] The signal generator is connected to two of the bending element components, namely the S-wave exciter and the P-wave exciter. The signal generator sends signals to the S-wave exciter and the P-wave exciter. In this embodiment, the preset interval is set to 10ms. When sending the signal, the signal generator alternately sends signals to the S-wave exciter and the P-wave exciter. The signal is an excitation signal voltage pulse; under the action of this signal, the S-wave exciter generates a transverse shear wave, and the P-wave exciter compresses the shear wave, and preferably continuously changes the pulse voltage frequency within the frequency range of 2~50 kHz until the oscilloscope records clear S and P shear wave signals.

[0092] 105. The system calculates the small strain stiffness G of water-sensitive soft subgrade soil based on the shear wave displayed on the oscilloscope. max And the lateral limit modulus M0, so according to the small strain stiffness G max And the lateral limit modulus M0 are used to monitor the water-sensitive soft roadbed soil.

[0093] According to the frequency in step 104, the terminal starts to collect and analyze the shear waves displayed in the oscilloscope at a preset time interval, and then starts to calculate the small strain stiffness G of the water-sensitive soft roadbed soil. max And the lateral limit modulus M0, the small strain stiffness G max The lateral limit modulus M0 is used to monitor and evaluate the water-sensitive soft soil roadbed. The objects of monitoring and evaluation are water-sensitive soft soil mixed with improved materials, that is, improved expansive soil.

[0094] During the monitoring and evaluation process, the small strain stiffness G of water-sensitive soft subgrade soil is firstly max Monitor the long-term stability of water-sensitive soft soil roadbed stiffness over time;

[0095] Secondly, by monitoring the small strain stiffness G of water-sensitive soft roadbed soil in different sections max The loss rate k G , initial small strain stiffness G1, stabilization time Δt and expansion potential quantitative parameter ε x The relationship between the maximum allowable expansion rate of highway subgrade soil and the expansion potential ε of water-sensitive soft subgrade soil is predicted by using the maximum allowable expansion rate of highway subgrade soil. x The stability and treatment quality of water-sensitive soft soil roadbed are quantitatively evaluated by the method of

[0096] Optionally, calculate the small strain stiffness G of water-sensitive soft subgrade soil based on the shear wave displayed in the oscilloscope max The detailed process of the lateral limit modulus M0 is as follows:

[0097] Determine the propagation speed of the P shear wave and the S shear wave between the two bending element components respectively, and obtain V s and V P ;

[0098] The small strain stiffness G is calculated according to the following formula max And lateral limit modulus M0:

[0099]

[0100]

[0101] Where ρ is the dry density of water-sensitive soft roadbed soil; S-shear wave is the shear wave transmitted between the S-wave exciter and the S-wave receiver. Similarly, P-shear wave is obtained.

[0102] In practice, we first determine the system delay time Δts, Δtp: Under the selected appropriate excitation frequency, according to the excitation and reception shear wave signals obtained when the bending elements that excite and receive shear wave signals contact each other, such as Figure 8 As shown, Δts and Δtp are obtained.

[0103] Then determine the total time t from the excitation to the reception of S and P shear wave signals. s0 , t p0 :At the selected frequency, according to the method of first arrival wave, Figure 9 The S shear wave signal and Figure 10 The total time t from the excitation to the reception of the S and P shear wave signals is obtained. s0 , t p0 .

[0104] Then determine the propagation time t of S and P shear waves in the improved expansive soil s , t p , the calculation formula is as follows:

[0105] (Formula 1)

[0106] (Formula 2)

[0107] Then determine the propagation velocity V of S and P shear waves s 、V p , the calculation formula is as follows:

[0108] (Formula 3)

[0109] (Formula 4)

[0110] Where L is the shear wave propagation distance, which is calculated as follows:

[0111] (Formula 5)

[0112] Where D is the inner diameter of the monitoring frame; a is the depth of the bending element inserted into the soil. In this application, the depth of the bending element inserted is 5 mm.

[0113] Finally, the small strain stiffness G of the improved expansive soil roadbed is calculated max , lateral limit modulus M0: small strain stiffness G of improved expansive soil roadbed max , The calculation formula of the lateral limit modulus M0 is as follows:

[0114] (Formula 6)

[0115] (Formula 7)

[0116] Also, please continue to read Figure 11 , calculate the small strain stiffness G of water-sensitive soft roadbed soil during monitoring period max The loss rate k G as follows:

[0117] Real-time recording of small strain stiffness G max (t), perform linear fitting on the data points in the decay time period, and take the slope of the fitting line as the small strain stiffness G of the subgrade soil during the monitoring period. max The loss rate k G , the calculation formula is as follows:

[0118] (Formula 8)

[0119] The cumulative volume strain Δθ of the modified expansive soil roadbed deformation during the monitoring period is calculated as follows:

[0120] First, the Poisson's ratio ν(t) of the improved expansive roadbed soil during the monitoring period is calculated and recorded in real time. Figure 12 As shown, the lateral limit modulus M0 (t) is recorded in real time; Figure 13 As shown, according to the real-time recorded G max (t), lateral limit modulus M0(t), real-time calculation and recording of Poisson's ratio ν(t) of the improved expansive roadbed soil during the monitoring period. The calculation formula is as follows:

[0121] (Formula 9)

[0122] Secondly, the axial strain ε(t) of the improved expansive soil roadbed during the monitoring period is recorded in real time. Figure 14 As shown in Figure 1, at the corresponding time point, the strain gauge data collected by the terminal is used to record the axial strain ε(t) of the water-sensitive soft soil roadbed in real time.

[0123] Finally, the cumulative volume strain Δθ after the deformation of the improved expansive soil roadbed stabilizes during the monitoring period is calculated. In the period from the beginning of the change of the axial strain ε(t) to the stability, n time points are uniformly selected, where n is greater than 10. The Poisson's ratio, axial strain, and volume strain at time i are respectively denoted as ν i , ε i ,θ i , then the volume strain θn at time n can be calculated as follows:

[0124] (Formula 10)

[0125] Where θ is the volume strain of the improved expansive roadbed soil; ε is the axial strain of the improved expansive roadbed soil; and ν is the arithmetic mean of the Poisson's ratio of the improved expansive roadbed soil before and after strain.

[0126] Since the improved expansive roadbed soil is a small strain deformation, the magnitude of its volume strain and axial strain is small, so Formula 3 can be simplified to the following form:

[0127] (Formula 11)

[0128] where θ i -1, θ i is the volume strain at moment i-1, i; ν i -1, ν i is the Poisson's ratio at the i-1th and i-th moments; ε i -1, ε i is the axial strain at moment i-1, i.

[0129] Establishment of soil expansion potential ε of improved expansive soil roadbed x The prediction function relationship, the prediction function relationship process is as follows:

[0130] First, calculate the expansion potential ε of the improved expansive soil roadbed x , expansion potential ε x It is expressed by the volume expansion rate of geotechnical materials under unloaded conditions, and the formula is as follows:

[0131] Under the condition that the improved expansive soil roadbed is not loaded, ε x The calculation formula is:

[0132] (Formula 12)

[0133] Where V solid is the particle volume of the improved expansive soil roadbed; e0 is the initial porosity of the improved expansive soil roadbed; Δe is the change in porosity of the improved expansive soil roadbed; θ x In order to improve the volume strain of expansive soil roadbed under unloaded conditions, it can be obtained by correcting the field data. The calculation formula is as follows:

[0134] (Formula 13)

[0135] Where A, B, and m are constants that can be obtained from the expansion rate test data under different loading conditions indoors; σ′ is the deadweight earth pressure at the test depth; p a is atmospheric pressure.

[0136] Combining Formula 12 with Formula 13, we can obtain the expansion potential ε of the improved expansive soil roadbed: x .

[0137] Secondly, the expansion potential ε of improved expansive soil subgrade was established xAccording to the functional relationship between the cumulative axial strain Δε and ε of the improved expansive soil roadbed at the five selected monitoring locations, x , establish Δε-ε x The relationship curve is fitted using a polynomial function. The general equation of the fitting curve is as follows:

[0138] (Formula 14)

[0139] where α i , n is a constant, which can be obtained by fitting the curve; Figure 15 As shown, in this example, n=3, α0=-0.49, α1=-0.23, and α2=-0.027.

[0140] Since the cumulative axial strain Δε of the improved expansive soil roadbed during the monitoring period has a functional relationship with the small strain stiffness loss rate kG, the functional relationship is as follows:

[0141] (Formula 15)

[0142] (Formula 16)

[0143] (Formula 17)

[0144] Where a and b are constants, which can be obtained by substituting field monitoring data or indoor test data into Formulas 15 and 16; γ is the shear strain; G1 is the initial small strain stiffness at the first moment; Δt is the time required for the axial strain of the improved expansive soil roadbed to change from 0 to Δε.

[0145] Finally, by combining Formula 14 and Formula 17, we can obtain the predicted expansion potential ε of the improved expansive soil roadbed: x The functional relationship of , assuming the general form of the functional relationship equation is:

[0146] ε x =F(kG,G1,Δt) (18)

[0147] When evaluating the stability of improved expansive soil roadbed, the evaluation process is as follows:

[0148] First, calculate the allowable expansion potential of the improved expansive soil roadbed [ε x ], the calculation formula is as follows:

[0149] (Formula 19)

[0150] (Formula 20)

[0151] where θ 50is the soil expansion rate under a load of 50 kPa; β, δ, and η are constants that can be obtained through expansion rate tests under different load conditions; Ψ is the safety factor, ranging from 0 to 1.

[0152] Simultaneously formula 12, formula 13, formula 19, formula 20, when θ 50 Taking the maximum value, we can get the allowable expansion potential [ε x ].

[0153] Secondly, the stability of the improved expansive soil roadbed is evaluated. The conditions for evaluating the stability of the improved expansive soil roadbed are:

[0154] (Formula 21)

[0155] If the ε predicted by formula 18 x If formula 21 is satisfied, the quality of the improved expansive soil roadbed is considered qualified, and the predicted εx is used to quantitatively evaluate the quality of the improved expansive soil roadbed; otherwise, the quality of the improved expansive soil roadbed is considered unqualified.

[0156] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0157] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0158] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0159] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0160] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, read-only memory), random access memory (RAM, random access memory), disk or optical disk, and other media that can store program code.

Claims

1. A method for monitoring the stability of water-sensitive soft soil highway engineering, characterized in that: The monitoring method depends on the monitoring system and includes: Determine the location points to be monitored; Setting a test pit at the location point; Placing the monitoring frame in the test pit and filling the test pit with improved expansive soil, wherein the improved expansive soil is formed by adding lime, fly ash, cement, chemical stabilizer and gravel to water-sensitive soft soil; Sending a signal to the bending element assembly at a preset interval through a signal generator, so that the bending element assembly generates a shear wave and displays it on an oscilloscope; Calculate the small strain stiffness G of water-sensitive soft subgrade soil based on the shear wave displayed in the oscilloscope max And the lateral limit modulus M0, so according to the small strain stiffness G max and the lateral limit modulus M0 to monitor the water-sensitive soft roadbed soil; According to the small strain stiffness G max Monitoring the water-sensitive soft roadbed soil using the lateral limit modulus M0 includes: Based on the small strain stiffness G max and the lateral limit modulus M0 to calculate the expansion potential εx of the improved expansive soil, and judge whether the quality of the improved expansive soil roadbed is qualified by comparing the expansion potential εx with the allowable expansion potential [εx]; if the expansion potential εx is less than or equal to the allowable expansion potential [εx], then the quality of the improved expansive soil roadbed is judged to be qualified, and the allowable expansion potential [εx] is calculated under a load of 50 kPa; The monitoring system comprises: Monitoring frame, oscilloscope, signal generator and terminal; The monitoring frame is arranged in a water-sensitive soft soil roadbed, and four bending element assemblies are arranged on the monitoring frame. A device socket is provided at the connection between the monitoring frame and the bending element assembly, and the device socket is embedded in the monitoring frame. The bending element assembly is connected to the device socket and protrudes inwardly from the inner wall of the monitoring frame. The four bending element assemblies are all connected to the oscilloscope, and two adjacent bending element assemblies are connected to the signal generator; The terminal is connected to the signal generator and the oscilloscope respectively; thereby controlling the signal generator to transmit a signal to the bending element assembly, the bending element assembly is used to generate a shear wave through the signal and display it on the oscilloscope, and the terminal is used to monitor the water-sensitive soft soil roadbed through the shear wave; A cutter is provided at the bottom of the monitoring frame, and the cutter is used to fix the monitoring frame on the water-sensitive soft soil roadbed.

2. The monitoring method according to claim 1, characterized in that The monitoring frame further comprises a rubber plug, which is located beside the device socket and connected to the monitoring frame. The rubber plug is used to plug the device socket.

3. The monitoring method according to claim 1, characterized in that The device socket includes a device slot and a gasket; The gasket is located at the bottom of the device slot and is flush with the inner wall of the monitoring frame. A rubber membrane is provided in the gasket. A gap is provided between the rubber membrane and the gasket. The bending element assembly is fixed in the device slot through the gap.

4. The monitoring method according to claim 3, characterized in that: The gasket is made of stainless steel; and / or; The device slot is made of chlorinated polyethylene.

5. The monitoring method according to claim 3, characterized in that: The width of the gap is 10-14 mm.

6. The monitoring method according to any one of claims 1 to 5, characterized in that: The bending element assembly includes a bending element, a cable connector and a device base; The device base is connected to the monitoring frame, and the bending element is fixed on the device base and connected to the cable connector.

7. The monitoring method according to any one of claims 1 to 5, characterized in that: The monitoring frame is made of stainless steel.

8. The monitoring method according to any one of claims 1 to 5, characterized in that: Two adjacent bending element assemblies are perpendicular to each other.

9. The monitoring method according to claim 1, characterized in that: The small strain stiffness G of the water-sensitive soft roadbed soil is calculated based on the shear wave displayed in the oscilloscope. max And the lateral limit modulus M0 includes: Determine the propagation speed of the P shear wave and the S shear wave between the two bending element components respectively, and obtain V s and V P ; The small strain stiffness G is calculated according to the following formula max And lateral limit modulus M0: Where ρ is the dry density of water-sensitive soft subgrade soil.

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