Method for comprehensively evaluating grouting effect of tunnel face based on continuous current excitation

Abstract

The invention relates to a tunnel face grouting effect comprehensive evaluation method based on continuous current excitation. The method comprises the steps that hole positions are arranged, specifically, a preset number of electrode hole positions, blast hole positions and receiver hole positions are drilled in the two side hole walls behind a tunnel face respectively; data acquisition: before and after grouting, respectively applying TSP once to obtain kinetic parameters of surrounding rock in front of the tunnel through a TSP data acquisition device; the automatic excitation receiving device is used for controlling the transmitting electrodes to transmit signals according to the preset frequency, the voltage data corresponding to all the receiving electrodes are sequentially received according to the preset sequence, the water-containing body information in front of grouting is obtained according to the transmitting signals and all the voltage data, and forecasting is carried out according to the water-containing body information in the grouting process. A surrounding rock water-rich state is obtained according to water-containing body information before and after grouting; and grouting effect evaluation: evaluating the tunnel grouting effect according to the kinetic parameters of the surrounding rock in front of the tunnel obtained by applying the TSP before and after grouting and the water-rich state of the surrounding rock before and after grouting.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel engineering, and in particular to a comprehensive evaluation method for tunnel face grouting effect based on continuous current excitation. Background Art

[0002] During tunnel excavation, water gushing from the tunnel may cause flooding, mudslides and other disasters, seriously threatening the lives of construction workers. Rapid changes in the groundwater level may cause the soil and rocks above or around the tunnel to loosen, leading to tunnel collapse, causing serious traffic disruptions and casualties. Therefore, reinforcement measures such as pre-grouting to block water are required, and the grouting effect needs to be evaluated after grouting.

[0003] At present, the commonly used methods for evaluating grouting effects include the PQt curve method, the inspection hole method, the in-hole phase method, the water inflow comparison method, etc. Although these methods are simple and easy to use, they only reflect the information within the local range of the grouting hole and lack the macroscopic control of the grouting effect of the grouting section. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a comprehensive evaluation method for the grouting effect of a tunnel face based on continuous current excitation.

[0005] To solve the above problems, the technical solution adopted by the present invention is: A comprehensive evaluation method for grouting effect of a tunnel face based on continuous current excitation, the method comprising: Step 1: Lay out holes A predetermined number of electrode holes, blast holes and receiver holes are drilled on the tunnel walls on both sides behind the tunnel face; transmitting electrodes or receiving electrodes are arranged in the electrode holes, and both the transmitting electrodes and the receiving electrodes are connected to an automatic excitation receiving device; Step 2: Data Acquisition Before and after grouting, TSP is applied once to transmit data to the computing device through the TSP data acquisition device to obtain the dynamic parameters of the surrounding rock in front of the tunnel; The transmitting electrode is controlled to transmit a signal at a predetermined frequency by an automatic excitation receiving device, and the voltage data corresponding to all receiving electrodes are received in sequence according to a predetermined order, and transmitted to a computing device, wherein the computing device obtains water-containing body information before grouting according to the transmitting signal and all voltage data, performs a forecast according to the water-containing body information during the grouting process, and obtains the water-rich state of the surrounding rock according to the water-containing body information before and after grouting; Step 3: Evaluation of grouting effect The computing equipment evaluates the tunnel grouting effect based on the dynamic parameters of the surrounding rock in front of the tunnel obtained by applying TSP before and after grouting, as well as the water-rich state of the surrounding rock before and after grouting.

[0006] As an implementation mode of the present invention, in step one, transmitting electrodes are arranged in a pair of electrode holes farthest from the tunnel face, and receiving electrodes are arranged in other holes, and positive electrodes are arranged in the electrode holes on one side of the tunnel wall, and negative electrodes are arranged in the electrode holes on the other side of the tunnel wall, and all the transmitting electrodes and receiving electrodes are connected to the automatic excitation receiving device.

[0007] As an implementation mode of the present invention, in order to enhance the detection of the water body above, the angle α between the line connecting the center lines of all electrode holes on each side of the tunnel wall and the longitudinal axis of the tunnel is 0-30°.

[0008] As an implementation mode of the present invention, the predetermined number of electrode holes on each side of the tunnel wall is 5 to 6, the horizontal spacing D1 between any two adjacent holes is 5 to 10 m, the electrode hole farthest from the tunnel face is located on the center line of the tunnel face; the depth of the hole is greater than or equal to 1.5 m.

[0009] As an embodiment of the present invention, in step one, explosives are arranged in the blast hole, a receiver is arranged in the receiver hole, the explosives are connected to the detonation device, and the receiver is connected to the TSP data acquisition device.

[0010] As an implementation mode of the present invention, in step 2, the water body information includes: the location and amount of water; The water content position and water content are obtained by automatically exciting the receiving device based on the current data I of the current in the transmitting electrode changing with time, and the voltage data V of the voltage in the receiving electrode at each receiving hole position changing with time.

[0011] As an implementation mode of the present invention, the automatic excitation receiving device realizes automatic switching of multiple receiving electrodes through a control system and a radio frequency switch, and has the functions of automatic data collection and remote transmission.

[0012] As an implementation mode of the present invention, step three includes: Step S301, determining the stability level of the surrounding rock before and after grouting according to the dynamic parameters before and after grouting, and determining the water content level of the surrounding rock according to the water-rich state of the surrounding rock before and after grouting; Step S302, using the following formula to obtain the surge risk probability P before and after grouting, and obtaining the surge risk change rate according to the difference between the surge risk probability P before and after grouting; P=Grade1*Grade2; Among them, Grade1 is the surrounding rock stability grade, and Grade2 is the surrounding rock water content grade; Step S303: Evaluate the grouting effect according to the sudden surge risk level corresponding to the sudden surge risk change rate and the sudden surge risk probability after grouting.

[0013] As an embodiment of the present invention, the method further includes: Step 4: Post-grouting effect evaluation After grouting, the safety of excavation in the grouting section is evaluated by continuously monitoring the changes in the water content of the surrounding rock in the grouting section to ensure safe construction of the tunnel.

[0014] The beneficial effects of adopting the above technical solution are: The comprehensive evaluation method of the grouting effect of the face based on continuous current excitation provided by the present invention continuously monitors the risk section of sudden water and mud before grouting, controls the scale and magnitude of the sudden surge risk, and guides the grouting design; during the grouting process, the grouting effect is macroscopically grasped by analyzing the distribution and change law of the water body in front; after grouting, the safety of the grouting section during excavation is evaluated by continuously monitoring the change of the water content of the surrounding rock of the grouting section, so as to ensure the safe construction of the tunnel. Therefore, the comprehensive evaluation method of the grouting effect of the face based on continuous current excitation provided by the present invention can comprehensively cover before grouting, during grouting, and after grouting, and is applicable to the preparatory stage of advanced reinforcement construction, the advanced reinforcement construction stage, the reinforcement effect evaluation stage, and the advanced reinforcement excavation stage, and has a wide range of applications. DETAILED DESCRIPTION

[0015] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is clearly and completely described below in conjunction with specific embodiments.

[0016] The embodiment of the present invention provides a comprehensive evaluation method for grouting effect of a tunnel face based on continuous current excitation, the method comprising: Step 1: Lay out holes A predetermined number of electrode holes, blast holes and receiver holes are drilled on the tunnel walls on both sides behind the tunnel face; transmitting electrodes or receiving electrodes are arranged in the electrode holes, and both the transmitting electrodes and the receiving electrodes are connected to an automatic excitation receiving device; Specifically, a transmitting electrode is arranged in a pair of electrode holes farthest from the tunnel face, and a receiving electrode is arranged in other holes, and positive electrodes are arranged in the electrode holes on one side of the tunnel wall, and negative electrodes are arranged in the electrode holes on the other side of the tunnel wall, and all the transmitting electrodes and receiving electrodes are connected to the automatic excitation receiving device; Explosives are arranged in the gun hole, a receiver is arranged in the receiver hole, the explosives are connected to the detonation device, and the receiver is connected to the TSP data acquisition device; How to set the gun hole position and receiver hole position: The setting method can adopt the method in the prior art, and the embodiment of the present invention does not specifically limit this. In a possible implementation method, it is as follows: Blast holes: Drill 24 blast holes side by side on the side wall near the face. The depth of the blast holes is ≥1.5m. The direction is perpendicular to the side wall and slightly downward at an angle of 15 degrees to facilitate watering. The spacing between each blast hole is 1.0~1.6m (e.g. 1.5m), and the height is 1.5m from the ground. The 24 blast holes can be in a horizontal straight line. The blast hole closest to the face should be as close to the face as possible.

[0017] Receiving hole: Arrange another receiving hole 15-20 m behind the 24th blast hole counted on the face. The height can be on the same horizontal plane as the blast hole. The hole depth is 2 m, the hole diameter is 50 mm, and the direction is perpendicular to the side wall with a slight downward angle of 15 degrees.

[0018] The electrode hole positions are set as follows: A predetermined number of electrode holes are drilled at equal intervals on the tunnel walls on both sides behind the tunnel face. For any side of the tunnel wall, the angle α between the line connecting the center lines of all the electrode holes and the longitudinal axis of the tunnel is 0~30°.

[0019] When α is 0°, all electrode holes are set horizontally; when 0°<α≤30°, the electrode holes are distributed obliquely downward in the direction away from the tunnel face, which can also enhance the detection of water content in the surrounding rock above the tunnel face.

[0020] The predetermined number of electrode holes on each side of the tunnel wall is 5 to 6, the horizontal spacing D1 between any two adjacent holes is 5 to 10 m, the electrode hole farthest from the tunnel face is located on the center line of the tunnel face; the depth of the hole is greater than or equal to 1.5 m.

[0021] Step 2: Data Acquisition Step S201, before and after grouting, TSP is applied once respectively to transmit data to a computing device through a TSP data acquisition device to obtain dynamic parameters of the surrounding rock in front of the tunnel; The dynamic parameters include the calculation of dynamic elastic modulus E d , dynamic shear modulus G d and Poisson's ratio μ d , the kinetic parameters are obtained using the following formula: ; ; ; Among them, ρ is the density of the surrounding rock, v p is the longitudinal wave velocity of the surrounding rock, v s is the shear wave velocity of the surrounding rock.

[0022] Step S202, control the transmitting electrode to transmit a signal at a predetermined frequency through an automatic excitation receiving device, and receive the voltage data corresponding to the receiving electrode in sequence according to a predetermined order, and transmit it to a computing device, the computing device obtains the water-containing body information before grouting according to the transmitting signal and all the voltage data, makes a forecast according to the water-containing body information during the grouting process, and obtains the water-rich state of the surrounding rock according to the water-containing body information before and after grouting.

[0023] The automatic excitation receiving device in the present invention specifically realizes automatic switching of multiple receiving electrodes through a control system and a radio frequency switch, and has the functions of automatic data collection and remote transmission. That is, the automatic excitation receiving device mainly controls the one-way output of the transmitting electrode and the multi-way reception of the receiving electrode through the principle of the radio frequency switch; cables are connected between the transmitting electrode and the receiving electrode to the automatic excitation receiving device to connect all the electrodes to the automatic excitation receiving device at one time.

[0024] Specifically, the present invention uses a microwave switch, which is a common radio frequency switch that uses the electromagnetic field generated by microwave elements to control the opening and closing of radio frequency signals; the radio frequency switch should not add additional electromagnetic wave reflections and other interferences, and should match the impedance of the acquisition card; the switching of multiple channels can be automatically controlled by a program, and manual switching is no longer required. At the same time, a wifi module can be added to allow the control device to be remotely connected to the Internet to achieve remote data transmission operations.

[0025] In the present invention, the predetermined frequency of the transmitting signal in the transmitting electrode is controlled to be an electromagnetic wave with a center frequency of 1 MHz and a frequency range of 200 KHz to 3 MHz. The predetermined order can be carried out according to the number of the receiving electrodes, for example: No. 1, No. 2. When arranging, the receiving electrodes with corresponding numbers can be placed in the electrode holes in advance; the collection can be automatically collected at preset time intervals, and the data of each different time period is processed as a separate set of data. For any set of data, the computing device obtains the water-containing body information in front of the grouting according to the transmitting signal and all the voltage data.

[0026] Among them, the water body information includes: the location and amount of water, and the location and amount of water are obtained by automatically exciting the receiving device based on the current data I of the current in the transmitting electrode changing with time, and the voltage data V of the voltage in the receiving electrode at each receiving hole position changing with time.

[0027] Specifically, the computing device calculates the normalized spectrum data based on the collected current data I and voltage data V, and uses the normalized spectrum data, combined with the coherent energy and coherent frequency of the reflected wave, to calculate the frequency corresponding to 1 / 4 wavelength for the position of each image point, and superimposes the data in the normalized spectrum corresponding to the frequency to obtain a synthetic hole position diameter map, thereby obtaining the water-containing body information in front of grouting.

[0028] In addition, the water-bearing body information includes: the location and amount of water-bearing body, and the surrounding rock water-rich state can be obtained based on the water-bearing body information. The surrounding rock water-rich state includes: the average dielectric constant of the surrounding rock and the water content of the surrounding rock.

[0029] Among them, in the present invention, the water content of the surrounding rock is divided into weak reflection, medium reflection and strong reflection according to the railway tunnel design specification, as shown in Table 1.

[0030] Table 1 Water-rich state of surrounding rock Step 3: Evaluation of grouting effect The tunnel grouting effect was evaluated based on the dynamic parameters of the surrounding rock in front of the tunnel obtained by applying TSP before and after grouting, as well as the water-rich state of the surrounding rock before and after grouting.

[0031] This step includes: Step S301, determining the stability level of the surrounding rock before and after grouting according to the dynamic parameters before and after grouting, and determining the water content level of the surrounding rock according to the water-rich state of the surrounding rock before and after grouting; In this step, according to the railway tunnel design specifications, the surrounding rock stability level is divided into five levels: very stable, stable, relatively stable, unstable, and extremely unstable according to the values ​​of the above-mentioned dynamic parameters, so that the surrounding rock stability level before and after grouting can be obtained based on this; The following method is used to determine the water content level of surrounding rock: The surrounding rock water content level is divided according to the measured average relative dielectric constant and the water-rich state of the surrounding rock; Among them, as shown in Table 1, when the average relative dielectric constant is 0-4, weak reflection is divided into surrounding rock water content level 1, medium reflection is divided into surrounding rock water content level 2, and strong reflection is divided into surrounding rock water content level 3; when the average relative dielectric constant is 4-10, weak reflection is divided into surrounding rock water content level 2, medium reflection is divided into surrounding rock water content level 3, and strong reflection is divided into surrounding rock water content level 4; when the average relative dielectric constant is >10, weak reflection is divided into surrounding rock water content level 3, medium reflection is divided into surrounding rock water content level 4, and strong reflection is divided into surrounding rock water content level 5.

[0032] Among them, the surrounding rock water content level 1 is dry, level 2 is wet, level 3 is dripping, level 4 is rain-like, and level 5 is stream-like gushing water.

[0033] The final classification of surrounding rock stability and water content is shown in Table 2.

[0034] Table 2 Classification of surrounding rock stability and water content Step S302, using the following formula to obtain the surge risk probability P before and after grouting, and obtaining the surge risk change rate according to the difference between the surge risk probability P before and after grouting; P=Grade1*Grade2; Among them, Grade1 is the surrounding rock stability grade, and Grade2 is the surrounding rock water content grade; In the present invention, the maximum surrounding rock stability grade and surrounding rock water content grade are both 5. For example, when the surrounding rock stability grade and surrounding rock water content grade before grouting are both 2, the sudden surge risk probability before grouting is P=2*2=4.

[0035] Thus, the probability P of sudden surge risk before and after grouting can be obtained.

[0036] The grouting effect can be determined based on the changes before and after grouting. For example, if the surrounding rock water content changes from a stream-like gushing or rain-like state to a wet or dry state before and after grouting, the grouting effect can be judged to be good. If the surrounding rock water content remains in a stream-like gushing state before and after grouting, the grouting effect can be judged to be poor; or, if the dynamic elastic modulus increases before grouting (the dynamic elastic modulus is closely related to the hardness and integrity of the rock. Generally speaking, the more complete and stronger the surrounding rock is, the greater the dynamic elastic modulus is), and the Poisson's ratio decreases (the Poisson's ratio is closely related to the water content of the rock and the ground stress. Generally speaking, the larger the Poisson's ratio is, the higher the water-richness of the surrounding rock is), the grouting effect can be judged to be good.

[0037] Therefore, in the present invention, after obtaining the surge risk probability P after grouting, the surge risk change rate is also obtained, and the subsequent grouting effect evaluation is performed based on these two indicators.

[0038] Step S303: Evaluate the grouting effect according to the sudden surge risk level corresponding to the sudden surge risk change rate and the sudden surge risk probability after grouting.

[0039] When the probability of sudden surge risk after grouting is between 1 and 4, the sudden surge risk level is Level I, which means almost no risk; when the probability of sudden surge risk after grouting is between 5 and 9, the sudden surge risk level is Level II, which means medium risk; when the probability of sudden surge risk after grouting is between 10 and 25, the sudden surge risk level is Level III, which means high risk.

[0040] The evaluation method is as follows: The above method is used to judge the risk level of sudden surge during tunnel construction. If the risk level of sudden surge is judged to be level III, prevention and control measures such as grouting reinforcement are required. If the risk level of sudden surge is judged to be level II, it can be determined whether prevention and control measures need to be taken based on the actual situation on site. If the risk level of sudden surge is judged to be level I, no additional measures are required.

[0041] For projects that are reinforced by grouting, it is also necessary to judge the risk level of sudden surge after grouting. In principle, the risk level of sudden surge after grouting should be level I to ensure construction safety. The lower the probability of sudden surge risk after grouting and the greater the rate of change of sudden surge risk, the better the grouting effect; when the sudden surge risk level after grouting is determined to be level I and the rate of change of sudden surge risk is greater than 10, it is determined that the grouting effect is good.

[0042] Step 4: Post-grouting effect evaluation After grouting, continuously monitor the changes in the water content of the surrounding rock in the grouting section, evaluate the safety during excavation of the grouting section, and ensure safe construction of the tunnel.

[0043] After grouting is completed, it is necessary to remove the stop wall, blast and excavate. Under the action of construction disturbance load, the surrounding rock at the weak grouting position will further deteriorate and become a potential water channel. In the present invention, the water content of the surrounding rock of the grouting section can be continuously monitored by automatically exciting the receiving device and the electrode, so as to evaluate the safety of the excavation of the grouting section and ensure the safe construction of the tunnel.

[0044] The comprehensive evaluation method of the grouting effect of the face based on continuous current excitation provided by the present invention continuously monitors the risk section of sudden water and mud before grouting, controls the scale and magnitude of the sudden surge risk, and guides the grouting design; during the grouting process, the grouting effect is macroscopically grasped by analyzing the distribution and change law of the water body in front; after grouting, the safety of the grouting section during excavation is evaluated by continuously monitoring the change of the water content of the surrounding rock of the grouting section, so as to ensure the safe construction of the tunnel. Therefore, the comprehensive evaluation method of the grouting effect of the face based on continuous current excitation provided by the present invention can comprehensively cover before grouting, during grouting, and after grouting, and is applicable to the pre-reinforcement construction preparation stage, the pre-reinforcement construction stage, the reinforcement effect evaluation stage, and the pre-reinforcement excavation stage, and has a wide range of applications; in addition, this method provides a new idea for the quantitative evaluation of the grouting effect.

[0045] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A comprehensive evaluation method for grouting effect of a tunnel face based on continuous current excitation, characterized in that: The method comprises: Step 1: Lay out holes A predetermined number of electrode holes, blast holes and receiver holes are drilled on the tunnel walls on both sides behind the tunnel face; transmitting electrodes or receiving electrodes are arranged in the electrode holes, and both the transmitting electrodes and the receiving electrodes are connected to an automatic excitation receiving device; Step 2: Data Acquisition Before and after grouting, TSP is applied once to transmit data to the computing device through the TSP data acquisition device to obtain the dynamic parameters of the surrounding rock in front of the tunnel; The transmitting electrode is controlled to transmit a signal at a predetermined frequency by an automatic excitation receiving device, and the voltage data corresponding to all receiving electrodes are received in sequence according to a predetermined order, and transmitted to a computing device, wherein the computing device obtains water-containing body information before grouting according to the transmitting signal and all voltage data, performs a forecast according to the water-containing body information during the grouting process, and obtains the water-rich state of the surrounding rock according to the water-containing body information before and after grouting; Step 3: Evaluation of grouting effect The computing equipment evaluates the tunnel grouting effect based on the dynamic parameters of the surrounding rock in front of the tunnel obtained by applying TSP before and after grouting, as well as the water-rich state of the surrounding rock before and after grouting.

2. A comprehensive evaluation method for grouting effect of a tunnel face based on continuous current excitation according to claim 1, characterized in that: In step 1, transmitting electrodes are arranged in a pair of electrode holes farthest from the tunnel face, and receiving electrodes are arranged in other holes. Positive electrodes are arranged in the electrode holes on one side of the tunnel wall, and negative electrodes are arranged in the electrode holes on the other side of the tunnel wall.

3. A comprehensive evaluation method for grouting effect of a tunnel face based on continuous current excitation according to claim 2, characterized in that: In order to strengthen the detection of the water body above, the angle α between the line connecting the center lines of all electrode holes on each side of the tunnel wall and the longitudinal axis of the tunnel is 0~30°.

4. The method for comprehensive evaluation of grouting effect of a tunnel face based on continuous current excitation according to claim 2 is characterized in that: The predetermined number of electrode holes on each side of the tunnel wall is 5 to 6, the horizontal spacing D1 between any two adjacent holes is 5 to 10 m, the electrode hole farthest from the tunnel face is located on the center line of the tunnel face; the depth of the hole is greater than or equal to 1.5 m.

5. The method for comprehensive evaluation of grouting effect of a tunnel face based on continuous current excitation according to claim 1, characterized in that: In step one, explosives are arranged in the blast hole, a receiver is arranged in the receiver hole, the explosives are connected to a detonating device, and the receiver is connected to a TSP data acquisition device.

6. The method for comprehensive evaluation of grouting effect of a tunnel face based on continuous current excitation according to claim 1, characterized in that: In step 2, the water body information includes: the location and amount of water; The water content position and water content are obtained by automatically exciting the receiving device based on the current data I of the current in the transmitting electrode changing with time, and the voltage data V of the voltage in the receiving electrode at each receiving hole position changing with time.

7. The method for comprehensive evaluation of grouting effect of a tunnel face based on continuous current excitation according to claim 1, characterized in that: The automatic excitation receiving device realizes automatic switching of multiple receiving electrodes through a control system and a radio frequency switch, and has the functions of automatic data collection and remote transmission.

8. The method for comprehensive evaluation of grouting effect of a tunnel face based on continuous current excitation according to claim 1, characterized in that: Step three includes: Step S301, determining the stability level of the surrounding rock before and after grouting according to the dynamic parameters before and after grouting, and determining the water content level of the surrounding rock according to the water-rich state of the surrounding rock before and after grouting; Step S302, using the following formula to obtain the surge risk probability P before and after grouting, and obtaining the surge risk change rate according to the difference between the surge risk probability P before and after grouting; P=Grade1*Grade2; Among them, Grade1 is the surrounding rock stability grade, and Grade2 is the surrounding rock water content grade; Step S303: Evaluate the grouting effect according to the sudden surge risk level corresponding to the sudden surge risk change rate and the sudden surge risk probability after grouting.

9. The method for comprehensive evaluation of grouting effect of a tunnel face based on continuous current excitation according to claim 1, characterized in that: The method further comprises: Step 4: Post-grouting effect evaluation After grouting, the safety of excavation in the grouting section is evaluated by continuously monitoring the changes in the water content of the surrounding rock in the grouting section to ensure safe construction of the tunnel.

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