A micro-disturbance control method for shield tunneling

Abstract

The present invention relates to the field of shield tunneling, and specifically to a shield tunneling micro-disturbance control method, comprising the following steps: calculating soil bin pressure, which is obtained by the sum of lateral horizontal loosening pressure, groundwater pressure, and a set pre-pressure, and can be adjusted according to the amount of soil cut and soil discharged; calculating shield thrust and cutter head torque, which is obtained by the front soil pressure of the shield equipment and the friction of the soil on the side; the cutter head torque includes the friction torque between the cutter head and the soil, the stratum resistance, and the torque generated by the cutter; calculating the propulsion speed, which is influenced by factors including the speed at which the shield machine outputs soil, the grouting speed, and the shield tail grease injection speed; and controlling the shield attitude, which is a dynamic adjustment process. Micro-disturbance control of tunneling is ensured by calculating multiple tunneling influencing factors such as the soil bin pressure and tunneling status.

Description

Technical Field

[0001] The present invention relates to the technical field of shield tunneling, and in particular to a shield tunneling micro-disturbance control method. Background Art

[0002] The shield method is a fully mechanized construction method in the underground excavation method. With the vigorous development of rail transit construction in major cities, the shield method has been widely used due to its good safety, high efficiency and low noise.

[0003] Compared to strata composed solely of mudstone, shield tunneling in fractured, rich mudstone formations causes greater settlement and disturbance to the strata. For older buildings with poor structural stability and weak resistance to surface deformation, improper settlement control can cause excessive ground and building settlement, leading to cracking, tilting, or even collapse, resulting in significant economic losses and adverse social impacts. Therefore, how to minimize ground settlement during shield tunneling in fractured, rich mudstone formations is a question that those skilled in the art need to consider. Summary of the Invention

[0004] The purpose of the present invention is to provide a shield tunneling micro-disturbance control method to solve the problems of large settlement caused by shield construction in cement-rich rock strata with developed fissures in the prior art.

[0005] The technical solution of the present invention is: a shield tunneling micro-disturbance control method, comprising the following steps:

[0006] S1. Calculate the soil bin pressure, which is obtained by the sum of the lateral horizontal loosening pressure, the groundwater pressure, and the set preparatory pressure, and can be adjusted according to the amount of soil cut and soil discharge;

[0007] S2. Calculate the shield thrust and cutterhead torque. The shield thrust is obtained by the front soil pressure of the shield equipment and the friction of the soil on the side. The cutterhead torque includes the friction torque between the cutterhead and the soil, the formation resistance, and the torque generated by the cutter.

[0008] S3. Calculate the advancement speed, where factors influencing the advancement speed include the speed at which the shield machine outputs soil, the grouting speed, and the grease injection speed at the shield tail;

[0009] S4. Control of the shield machine's posture. The control of the shield machine's posture is a dynamic adjustment process, including shield machine partition control, serpentine deviation correction, and rolling control.

[0010] Preferably, the soil bin pressure is calculated as follows:

[0011] Lateral loosening pressure for:

[0012] ;

[0013] in, ;

[0014] ;

[0015] therefore, ;

[0016] Where S is the surrounding rock type, which can be obtained from the table in the current "Railway Tunnel Design Code", B is the net width of the tunnel (m), and i is the rate of increase or decrease of the surrounding rock pressure when B increases or decreases by 1m, based on B=5m. When B<5m, i=0.2, and when B>5m, i=0.1.

[0017] Groundwater pressure calculate:

[0018] ;

[0019] Where: q is the empirical value determined based on the permeability coefficient of the soil; γ is the bulk density of water, γ = 10kN / m3; h is the height of the groundwater level from the top of the cutterhead.

[0020] Based on the above calculation, the set soil bin pressure for:

[0021] ;

[0022] Where, The set preparation pressure.

[0023] Preferably, when the shield advances, the shield body gradually sinks into the soil, and its thrust gradually increases. The shield thrust is calculated as follows:

[0024] The positive soil pressure is:

[0025] ;

[0026] The friction force of the soil on the side of the shield equipment is:

[0027] ;

[0028] in, is the pressure on the shield machine, ;

[0029] is the lateral water and soil pressure at the shield machine crown, ;

[0030] is the lateral water and soil pressure at the bottom of the shield machine, ;

[0031] is the uniform pressure at the bottom of the shield machine, ;

[0032] in, is the lateral earth pressure coefficient, is the weight of the shield machine, is the outer diameter of the shield machine, is the length of the shield machine, is the friction coefficient between the shield and the soil;

[0033] The shield thrust is: ;

[0034] in, To match the friction resistance of the trailer, take the empirical value.

[0035] Preferably, the friction torque between the cutter head and the soil includes the friction resistance torque between the front of the cutter head and the soil ; Friction resistance torque between the back of the cutterhead and the soil in the pressure chamber ; The formation resistance and the torque generated by the tool are , then the cutter head torque is:

[0036] ;

[0037] in, ;

[0038] ;

[0039] = ;

[0040] Where, is the positive earth pressure coefficient, is the friction factor between the cutterhead and the soil, is the gravity density of soil, is the tunnel depth (calculated to the tunnel center) (m), is the cutterhead opening ratio of the shield machine, The quality of the cutter head, is the cutter disc coefficient, is the cutterhead radius, is the outer diameter of the shield machine, is the tunneling speed of the shield machine, is the cutter head speed, is the uniaxial compressive strength of soil.

[0041] Preferably, in step S3, in the control of the speed of the shield machine outputting soil, the soil is discharged by the screw machine, and the amount of soil discharged needs to be controlled to maintain the volume balance of the amount of cut soil and the amount of soil discharged. When , the volume of soil removed is:

[0042] ;

[0043] in, is the outer diameter of the shield machine;

[0044] The weight of the soil removed is:

[0045] ;

[0046] in, is the density of the cut soil;

[0047] According to the maximum and minimum values ​​of the density of the cut soil, the maximum and minimum values ​​of the cut soil weight can be obtained:

[0048] ;

[0049] .

[0050] Preferably, in the control of the soil output speed, it is necessary to maintain a balance between the weight of the cut soil and the amount of soil discharged; the shield machine needs to be injected with water during cutting, and the natural soil to be cut needs to be improved by adding an improver solution before discharging the soil. The weight of discharged soil is:

[0051] ;

[0052] Then the maximum and minimum values ​​of the discharged soil are:

[0053] ;

[0054] ;

[0055] in, is the weight of the improver solution, which is an empirical value; The amount of water used during cutting is based on empirical values;

[0056] Volume of discharged soil:

[0057] ;

[0058] The maximum and minimum values ​​of the volume of discharged soil are:

[0059] ;

[0060] ;

[0061] in, The density of the discharged soil can be measured;

[0062] When the shield machine advances a distance L, the amount of soil discharged is controlled at and Within the range, when the amount of discharged soil is less than When the amount of soil discharged is greater than When the shield machine is running too fast or the screw machine is rotating too fast.

[0063] Preferably, the advancement speed is ensured and the tunnel segments are grouting synchronously with the shield machine.

[0064] Preferably, in step S4, the shield zoning control is divided into multiple hydraulic zones according to multiple groups of oil cylinders at the cutter head end of the shield machine, and each group is provided with a stroke sensor to perform separate pressure control so that the cutter head end of the shield machine is in an upward forward posture.

[0065] Compared with the prior art, the advantages of the present invention are:

[0066] (1) In the present invention, the required shield thrust can be calculated by calculating the soil bin pressure, and can be continuously optimized and adjusted during the excavation process to maintain the dynamic balance and stability of the pressure in the soil bin;

[0067] The tunneling speed is controlled by the thrust of the shield machine and the torque of the cutterhead. In combination with the relationship between the amount of soil discharged and the amount of cutting, during the actual tunneling process, the various working parameters of the shield machine can be optimized according to the actual geological conditions and the state of the soil discharged, so that the tunneling speed, shield thrust, cutterhead torque and screw conveyor transmission are kept in dynamic balance, thereby ensuring micro-disturbance control of tunneling.

[0068] (2) In terms of shield machine attitude control, the shield machine cutterhead maintains a slightly upward excavation trend through shield zoning control to avoid the shield machine from falling head due to its own weight, which may cause the shield machine attitude to lose control; the shield machine attitude is adjusted and corrected by adjusting the different propulsion speeds and pressures of each group of cylinders; and the shield machine rolling is corrected by rotating the cutterhead forward and backward. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0070] Figure 1 This is a flow chart of the control method of the present invention;

[0071] Figure 2This is a schematic diagram of the shield type soil pressure structure of the present invention. DETAILED DESCRIPTION

[0072] The present invention is further described in detail below with reference to specific embodiments:

[0073] As shown in the figure, the present invention applies shield tunneling technology to tunneling operations in fractured, cement-rich rock formations. By theoretically calculating soil bin pressure, shield thrust, propulsion speed, and adjusting the shield's posture, the effect of ground settlement during tunneling can be reduced. Specifically, a shield tunneling micro-disturbance control method includes the following steps:

[0074] S1. Calculate the soil bunker pressure, which is the sum of the lateral horizontal loosening pressure, groundwater pressure, and the set reserve pressure. Too low soil pressure will cause significant settlement and deformation. Setting the soil pressure too high will cause ground uplift, increase shield thrust and cutterhead torque, slow down excavation speed, and make soil improvement more difficult. Shield construction in fractured and cement-rich rock formations is more prone to mud cake formation in the soil bunker or on the cutterhead, causing even greater disturbance to the ground caused by shield excavation. The soil bunker pressure is primarily achieved by maintaining a balance between the excavation and discharge volumes. This can be achieved by setting the excavation speed and adjusting the discharge volume, or by setting the discharge volume and adjusting the excavation speed.

[0075] First, based on the determination method of deep and shallow buried tunnels, the calculated tunnel is determined to be a deep buried tunnel or a shallow buried tunnel. The boundary depth between deep and shallow buried tunnels is usually 2 to 2.5 times the average height of the construction collapse. This calculation and determination method is existing technology and will not be described in detail in this embodiment. This embodiment takes a deep buried tunnel as an example:

[0076] Lateral loosening pressure for:

[0077] ;

[0078] in, ;

[0079] ;

[0080] therefore, ;

[0081] Where S is the surrounding rock type, which can be obtained by looking up the table in the current "Railway Tunnel Design Code", B is the net width of the tunnel (m), and i is the rate of increase or decrease of the surrounding rock pressure when B increases or decreases by 1m based on B=5m. When B<5m, i=0.2, and when B>5m, i=0.1.

[0082] While the stratum generates vertical pressure, it also generates lateral pressure, lateral horizontal loosening pressure The calculation is shown in Table 1-1 below:

[0083] 1-1 Lateral horizontal loosening pressure

[0084]

[0085] Groundwater pressure calculate:

[0086] 1) When the shield machine stops, due to the existence of pressure head difference in the stratum, groundwater will inevitably continue to flow into the soil bin until the head pressure in the stratum is eliminated. The water pressure at this time is:

[0087] ;

[0088] Where: q is the empirical value determined based on the permeability coefficient of the soil; γ is the bulk density of water, γ = 10kN / m3; h is the height of the groundwater level from the top of the cutterhead.

[0089] 2) In actual construction, since underground water in the pipe may form a water channel along the gap outside the pipe segment, a certain pressure head will be formed when the shield is shut down for a long time.

[0090] ;

[0091] Where, It is an empirical value determined by the permeability coefficient of the mortar and the fullness of the grouting, generally ranging from 0.8 to 1.0; h is the height difference between the reinforcement grouting point and the top of the cutter head.

[0092] Groundwater pressure and The larger value of the two, this embodiment is based on > Take the value as an example.

[0093] Preparation pressure for:

[0094] Due to uncertainties that may arise during construction, the construction soil pressure is lower than the static soil pressure in the original soil. The value of soil pressure is usually determined based on theoretical calculations and a preliminary pressure of 10 to 20 kPa is considered.

[0095] Based on the above calculation, the set soil bin pressure for:

[0096] ;

[0097] In practice, to maintain excavation face stability, the set earth bunker pressure can be slightly greater than the calculated earth bunker pressure P. By comparing the actual earth pressure Pi within the shield bunker with the set earth pressure, the balance between the two is the control target, and soil discharge management is carried out based on this pressure difference.

[0098] S2. Calculate the shield thrust and cutterhead torque. The shield thrust is obtained by the front soil pressure of the shield equipment and the friction of the soil on the side. The cutterhead torque includes the friction torque between the cutterhead and the soil, the formation resistance and the torque generated by the cutter.

[0099] When the shield advances, the main body of the shield gradually sinks into the soil, and its thrust gradually increases. The shield thrust is calculated as follows:

[0100] The positive soil pressure is:

[0101] ;

[0102] The friction force of the soil on the side of the shield equipment is:

[0103] ;

[0104] in, is the pressure on the shield machine, ;

[0105] is the lateral water and soil pressure at the shield machine crown, ;

[0106] is the lateral water and soil pressure at the bottom of the shield machine, ;

[0107] is the uniform pressure at the bottom of the shield machine, ;

[0108] in, is the lateral earth pressure coefficient, is the weight of the shield machine, is the outer diameter of the shield machine, is the length of the shield machine, is the friction coefficient between the shield and the soil;

[0109] The shield thrust is: ;

[0110] in, To match the friction resistance of the trailer, take the empirical value.

[0111] The friction torque between the cutterhead and the soil includes the friction resistance torque between the front of the cutterhead and the soil ; Friction resistance torque between the back of the cutterhead and the soil in the pressure chamber ; The formation resistance and the torque generated by the tool are , the cutter head torque is:

[0112] ;

[0113] in, ;

[0114] ;

[0115] = ;

[0116] Where, is the positive earth pressure coefficient, is the friction factor between the cutterhead and the soil, is the gravity density of soil, is the tunnel depth (m), is the cutterhead opening ratio of the shield machine, The quality of the cutter head, is the cutter disc coefficient, is the cutterhead radius, is the outer diameter of the shield machine, is the tunneling speed of the shield machine, is the cutter head speed, is the uniaxial compressive strength of soil.

[0117] On the basis of soil bin pressure balance, the shield thrust and cutterhead torque are set to reduce the disturbance caused by shield tunneling to the surrounding strata.

[0118] S3. Calculate the advancement speed. Factors affecting the advancement speed include the speed at which the shield machine outputs soil, the grouting speed, and the grease injection speed at the shield tail.

[0119] During shield tunneling, the screw conveyor discharge system discharges soil in proportion to the shield's advance, always maintaining a balance between the amount of soil removed and the amount discharged to maintain the soil pressure within the bin. The pressure within the bin counteracts the soil and water pressure at the working face to maintain soil stability at the working face, preventing collapse of the working face and the inrush of groundwater. This allows the shield machine to advance in unmoved surrounding rock, ensuring no stratum loss and achieving an earth pressure balance tunneling mode. When the bin pressure is balanced, stable, and not overexcavated, the amount of soil removed per ring (segment width L) is equal to the amount of soil excavated by each ring of the cutterhead. The volume of soil removed is:

[0120] ;

[0121] in, is the outer diameter of the shield machine;

[0122] The weight of the soil removed is:

[0123] ;

[0124] in, is the density of the cut soil;

[0125] According to the maximum and minimum values ​​of the density of the cut soil, the maximum and minimum values ​​of the cut soil weight can be obtained:

[0126] ;

[0127] .

[0128] In the control of soil output speed, it is necessary to maintain the balance of the weight of the cut soil and the amount of soil discharged; the shield machine needs to be injected with water during cutting, and the natural soil to be cut needs to be improved by adding an improver solution before discharging the soil. The weight of discharged soil is:

[0129] ;

[0130] Then the maximum and minimum values ​​of the discharged soil are:

[0131] ;

[0132] ;

[0133] in, is the weight of the improver solution, which is an empirical value; The amount of water used during cutting is based on empirical values;

[0134] Volume of discharged soil:

[0135] ;

[0136] The maximum and minimum values ​​of the volume of discharged soil are:

[0137] ;

[0138] ;

[0139] in, The density of the discharged soil can be measured;

[0140] When the shield machine advances a distance L, the amount of soil discharged is controlled at and Within the range, when the amount of discharged soil is less than When the amount of soil discharged is greater than When the shield machine is running too fast or the screw machine is rotating too fast.

[0141] In this embodiment, shield earth removal adopts dual control indicators of weight and volume to control the amount of stratum loss, which generally does not exceed 3%, so as to achieve the goal of balancing the amount of soil removed and the amount of soil removed.

[0142] In the control of grouting rate, for synchronous grouting, the grouting speed and the advancing speed are kept synchronized, that is, sufficient grouting is carried out while the shield machine is advancing. Synchronous grouting adopts dual control of grouting pressure and grouting volume, with grouting volume control as the main method to ensure that the filling behind the pipe segment is dense and avoid soil disturbance.

[0143] Among them, the grouting volume is the amount of slurry required to fill the gap between the cut soil and the outer wall of the segment.

[0144] Grouting volume: Based on empirical formula calculations and previous shield construction experience, the grouting volume is 1.5 to 2 times the theoretical volume of the annular gap.

[0145] Theoretical grouting volume V=π(D2-d2)L / 4; ;

[0146] Theoretical grouting volume Q=(1.5~2.0)V;

[0147] Where: D is the cutterhead diameter, d is the outer diameter of the segment, and L is the segment width.

[0148] The synchronous grouting pressure is set so that the pressure at the injection port is greater than the sum of the static water pressure and the earth pressure at that point. If the grouting pressure is too high, the soil layer outside the segment will be disturbed by the slurry, causing ground uplift and easily leaking from the shield tail. If the grouting pressure is too low, the slurry filling speed will be too slow, and insufficient filling will also cause surface settlement and cause segment displacement.

[0149] S4. Shield posture control. Shield posture control is a dynamic adjustment process. The more unstable the shield posture and the greater the deviation adjustment, the greater the disturbance caused by shield construction. This mainly includes shield zone control, serpentine deviation correction, and rolling control.

[0150] Shield TBM zone control utilizes multiple cylinder groups at the cutterhead of the shield machine, dividing them into multiple hydraulic zones. Each group is equipped with a stroke sensor for independent pressure control, ensuring an upward-tilted tunneling posture. During shield tunneling, strict control of the shield's attitude is required to ensure smooth tunneling, minimize snaking and rolling, and control disturbances during shield construction. If rolling occurs, the cutterhead is rotated forward and reversed to correct the shield's attitude.

[0151] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they are not intended to limit the scope of protection of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A shield tunneling micro-disturbance control method, characterized in that: The following steps are involved: S1. Calculate the soil bin pressure, which is obtained by the sum of the lateral horizontal loosening pressure, the groundwater pressure, and the set preparatory pressure, and can be adjusted according to the amount of soil cut and soil discharge; S2. Calculate the shield thrust and cutterhead torque. The shield thrust is obtained by the front soil pressure of the shield equipment and the friction of the soil on the side. The cutterhead torque includes the friction torque between the cutterhead and the soil, the formation resistance, and the torque generated by the cutter. S3. Calculate the advancement speed, where factors influencing the advancement speed include the speed at which the shield machine outputs soil, the grouting speed, and the grease injection speed at the shield tail; S4, shield posture control, said shield posture control is a dynamic adjustment process, including shield zoning control, serpentine correction and rolling control; The calculation method of the soil bin pressure is: Lateral loosening pressure for: ； in, ; ; therefore, ; Where S is the surrounding rock type, B is the net width of the tunnel (m), and i is the rate of increase or decrease of surrounding rock pressure when B increases or decreases by 1m, based on the time when B=5m. When B<5m, i=0.2; when B>5m, i=0.

1. Groundwater pressure calculate: ; Where: q is an empirical value determined based on the permeability coefficient of the soil; γ is the bulk density of water, γ = 10kN / m3; h is the height of the groundwater level from the top of the cutterhead; Based on the above calculation, the set soil bin pressure for: ； Where, is the set preparation pressure; When the shield advances, the main body of the shield gradually sinks into the soil, and its thrust gradually increases. The shield thrust is calculated as follows: The positive soil pressure is: ; The friction force of the soil on the side of the shield equipment is: ; in, is the pressure on the shield machine, ; is the lateral water and soil pressure at the shield machine crown, ; is the lateral water and soil pressure at the bottom of the shield machine, ; is the uniform pressure at the bottom of the shield machine, ; in, is the lateral earth pressure coefficient, is the weight of the shield machine, is the outer diameter of the shield machine, is the length of the shield machine, is the friction coefficient between the shield and the soil; The shield thrust is: ; in, To match the friction resistance of the trailer, take the empirical value.

2. A shield tunneling micro-disturbance control method according to claim 1, characterized in that: The friction torque between the cutter head and the soil includes the friction resistance torque between the front of the cutter head and the soil ; Friction resistance torque between the back of the cutterhead and the soil in the pressure chamber ; The formation resistance and the torque generated by the tool are , then the cutter head torque is: ； in, ; ; = ; Where, is the positive earth pressure coefficient, is the friction factor between the cutterhead and the soil, is the gravity density of soil, is the tunnel depth (m), is the cutterhead opening ratio of the shield machine, The quality of the cutter head, is the cutter disc coefficient, is the cutterhead radius, is the outer diameter of the shield machine, is the tunneling speed of the shield machine, is the cutter head speed, is the uniaxial compressive strength of soil.

3. A shield tunneling micro-disturbance control method according to claim 2, characterized in that: In step S3, the shield machine discharges soil through the screw conveyor while controlling the speed of soil output. The amount of soil discharge needs to be controlled to maintain the volume balance between the amount of soil cut and the amount of soil discharge. When , the volume of soil removed is: ； in, is the outer diameter of the shield machine; The weight of the soil removed is: ； in, is the density of the cut soil; According to the maximum and minimum values ​​of the density of the cut soil, the maximum and minimum values ​​of the cut soil weight can be obtained: ； 。 4. A shield tunneling micro-disturbance control method according to claim 3, characterized in that: In the control of soil output speed, it is necessary to maintain the balance of the weight of the cut soil and the amount of soil discharged; the shield machine needs to be injected with water during cutting, and the natural soil to be cut needs to be improved by adding an improver solution before discharging the soil. The weight of discharged soil is: ； Then the maximum and minimum values ​​of the discharged soil are: ； ； in, is the weight of the improver solution, which is an empirical value; The amount of water used during cutting is based on empirical values; Volume of discharged soil: ； The maximum and minimum values ​​of the volume of discharged soil are: ； ； in, The density of the discharged soil can be measured; When the shield machine advances a distance L, the amount of soil discharged is controlled at and Within the range, when the amount of discharged soil is less than When the amount of soil discharged is greater than When the shield machine is running too fast or the screw machine is rotating too fast.

5. The shield tunneling micro-disturbance control method according to claim 1, characterized in that: In step S4, the shield machine is controlled by dividing the multiple groups of oil cylinders at the cutter head end of the shield machine into multiple hydraulic zones, each group is provided with a stroke sensor, and a separate pressure control is performed so that the cutter head end of the shield machine is in an upward forward posture.

Images