Hob rock breaking synergy and consumption reduction method based on optimal specific energy and limit load

Abstract

The invention discloses a hob rock breaking efficiency-increasing and consumption-reducing method based on optimal specific energy and limit load, and relates to the technical field of tunnel boring machines, and the method comprises the following steps: obtaining an operation parameter with optimal hob rock breaking specific energy through a hob rock breaking indoor experiment; establishing a matching relationship between the hob operation parameters and the rock uniaxial compressive strength under the optimal specific energy; establishing a matching relationship between the hob operation parameters under the limit load and the uniaxial compressive strength of the rock; according to the optimal specific energy and the limit load of rock breaking of the hob, the penetration degree of rock breaking of the hob is determined to achieve efficiency improvement and consumption reduction; the hobbing cutter has the beneficial effects that the rock breaking efficiency of the hobbing cutter can be improved by reducing the rock breaking specific energy of the hobbing cutter, and the consumption of the hobbing cutter can be reduced by limiting the load of the hobbing cutter.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel boring machines, and particularly to a method for enhancing the rock-breaking efficiency and reducing energy consumption of disc cutters based on the optimal special energy and ultimate load. Background Art

[0002] As a "national key equipment" in the field of underground engineering, the Tunnel Boring Machine (TBM) has become an important symbol to measure the level of a country's high-end equipment manufacturing. With the in-depth implementation of the "Transportation Power" strategy, the scale of tunnel projects under construction in China has exceeded 23,000 kilometers, and the proportion of projects constructed by TBM has climbed from 15% in 2010 to 42% in 2022, with the localization rate of core equipment exceeding 85%. However, China's geological structure has typical characteristics of "three highs and three complexities" - high altitude, high ground stress, high-intensity seismic belts, and the superposition of complex strata, complex structures, and complex environments, resulting in world-class problems in TBM construction. Taking the Sichuan-Tibet Railway as an example, its tunnel project passes through the "geological museum" of the Hengduan Mountains, and a single tunnel needs to cope with the drastic phase change from ultra-hard granite of 200 MPa level to grade V soft surrounding rock, which poses strict requirements on the adaptability of the TBM's core rock-breaking tool - the disc cutter.

[0003] Currently, the optimization of disc cutter rock-breaking efficiency faces dual technical bottlenecks: First, the traditional parameter design theory has the defects of "experience dependence" and "theory disconnection". Although domestic and foreign scholars have established classic prediction models such as CSM and NTNU, their linear constitutive relations based on the assumption of homogeneous rock mass have significant deviations from engineering practice. For example, in the construction of a deep-buried tunnel in the southwest, the cutter spacing / penetration ratio (S / h = 15) set according to traditional theory results in a rock-breaking specific energy as high as 12.5 MJ / m 3 in the basalt section, which is 68% higher than the theoretical value; Second, the load control technology has problems of "passive protection" and "dynamic mismatch". Most of the existing overload protections for disc cutters adopt threshold trigger mechanisms such as pressure relays. During the construction of the sandstone-shale interlayer section of a water diversion project in North China, the peak value of the instantaneous impact load of the disc cutter can reach 3.2 times the average value, resulting in an average of 7.3 abnormal cutter changes per month and a direct cost increase of 21%. It can be seen that when the operating parameters of the disc cutter do not match the rock strength, the rock-breaking efficiency of the disc cutter is low and the TBM tunneling speed is slow; at the same time, when the load on the disc cutter exceeds its bearing capacity, the disc cutter is extremely easy to be damaged and the consumption of disc cutters is large. The 2022 annual report of the International Tunneling Association (ITA) pointed out that the cost of disc cutter consumption has accounted for 35%-40% of the total cost of hard rock tunnel construction, and the abnormal loss rate of disc cutters under complex geological conditions in China is 18 percentage points higher than the international average level. Summary of the Invention

[0004] The object of the present invention is to provide a method for enhancing the efficiency and reducing the consumption of hob rock breaking based on the optimal specific energy and the ultimate load, which can not only improve the hob rock breaking efficiency by reducing the specific energy of hob rock breaking, but also reduce the hob consumption by limiting the hob load.

[0005] The present invention realizes the above object through the following technical solutions:

[0006] A method for enhancing the efficiency and reducing the consumption of hob rock breaking based on the optimal specific energy and the ultimate load includes the following steps:

[0007] Step S1: Obtain the operating parameters with the optimal specific energy of hob rock breaking through indoor hob rock breaking experiments on a certain kind of rock with uniaxial compressive strength.

[0008] Step S2: Conduct experiments on rocks with different uniaxial compressive strengths by the method of Step S1, and establish the matching relationship between the hob operating parameters and the uniaxial compressive strength of the rock under the optimal specific energy.

[0009] Step S3: Conduct hob rock breaking experiments on rocks with different uniaxial compressive strengths to determine the operating parameters of the hob when it bears the ultimate load, and then establish the matching relationship between the hob operating parameters and the uniaxial compressive strength of the rock under the ultimate load. This matching relationship is used to reflect the corresponding law between the operating parameters and the uniaxial compressive strength of the rock when the hob bears the ultimate load.

[0010] Step S4: Combine the matching relationship between the hob operating parameters and the uniaxial compressive strength of the rock established in Step S2 under the optimal specific energy and the matching relationship between the hob operating parameters and the uniaxial compressive strength of the rock established in Step S3 under the ultimate load, and comprehensively consider the requirements of the optimal specific energy and the ultimate load of hob rock breaking to determine the penetration of hob rock breaking. The efficiency enhancement and consumption reduction of hob rock breaking are realized by reasonably setting this penetration.

[0011] Preferably: The specific content of Step S1 is to conduct indoor hob rock breaking experiments under different operating parameter conditions, and establish the fitting relationship between the specific energy of hob rock breaking and the operating parameters by using the indoor hob rock breaking experimental data.

[0012] Preferably: The fitting relationship between the specific energy of hob rock breaking and the operating parameters is SE = a(S / h)2 - b(S / h) + c, where SE is the specific energy of hob rock breaking for a certain kind of rock with uniaxial compressive strength, and the abscissa of the vertex of the quadratic function is the operating parameter S / h with the optimal specific energy of hob rock breaking, that is, b / (2a).

[0013] Preferably: The specific content of Step S2 is to obtain the hob operating parameter S / h with the optimal specific energy under the conditions of rocks with different uniaxial compressive strengths by the method of Step S1, and establish the fitting relationship between the hob operating parameter S / h and the uniaxial compressive strength σ of the rock under the optimal specific energy.

[0014] Preferably, the fitting relationship between the hob operating parameter S / h and the uniaxial compressive strength σ of the rock under the optimal specific energy is:

[0015] S / h = -0.0022σ 2 + 0.4692σ + 8.9577, (1)

[0016] In the formula, S is the cutter spacing, in mm; h is the penetration depth, in mm; σ is the uniaxial compressive strength of the rock, in MPa.

[0017] Preferably, the specific step S3 is to establish a calculation formula for the vertical load of hob rock breaking, and based on the calculation formula for the vertical load of hob rock breaking, the hob operating parameters under the limit load are calculated inversely, and the matching relationship between the hob operating parameters under the limit load and the uniaxial compressive strength of the rock is obtained.

[0018] Preferably, the calculation formula for the vertical load of hob rock breaking is:

[0019]

[0020] In the formula, F is the vertical load of hob rock breaking, in N, and the limit value is 250×10 3 N; T is the width of the cutting edge, in mm, and for a hob with a standard cutting edge width, it is taken as 19 mm; D is the diameter of the hob, in mm, and for a commonly used 19-inch hob, it is taken as 483 mm; σ is the compressive strength of the rock, in MPa.

[0021] Preferably, the matching relationship between the hob operating parameters under the limit load and the uniaxial compressive strength of the rock is:

[0022] S·h = 1.827×10 9 σ -3 (3).

[0023] Preferably, the specific step S4 is to calculate the penetration depth of hob rock breaking under different uniaxial compressive strengths of the rock and different cutter spacing conditions according to the relationship between the operating parameters of the hob under the optimal specific energy of rock breaking and the uniaxial compressive strength of the rock, which is called the penetration depth under the optimal specific energy; calculate the penetration depth of hob rock breaking under different uniaxial compressive strengths of the rock and different cutter spacing conditions according to the relationship between the operating parameters of the hob under the limit load of rock breaking and the uniaxial compressive strength of the rock, which is called the penetration depth under the limit load;

[0024] When the penetration depth under the limit load ≥ the penetration depth under the optimal specific energy, the penetration depth of hob rock breaking takes the penetration depth under the optimal specific energy to achieve efficient rock breaking of the hob; when the penetration depth under the limit load < the penetration depth under the optimal specific energy, the penetration depth of hob rock breaking takes the penetration depth under the limit load to achieve energy-saving rock breaking of the hob.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] Improve the rock-breaking efficiency of the hob: By determining the optimal operating parameters of the specific energy of hob rock-breaking, reduce the specific energy of hob rock-breaking, thereby enhancing the rock-breaking efficiency of the hob; specifically, calculate the optimal specific energy penetration of the hob based on the uniaxial compressive strength of the rock and the cutter spacing to achieve efficient rock-breaking of the hob;

[0027] Reduce the hob consumption: By restricting the vertical load of the hob, avoid abnormal wear caused by hob overload; specifically, calculate the limit load penetration of the hob according to the limit load condition of hob rock-breaking to ensure that the hob operates within a safe range and extend the service life of the hob;

[0028] Strong adaptability: The method of the present invention can adapt to the rock-breaking requirements of hobs under different uniaxial compressive strengths of rocks and different cutter spacings, provide a flexible penetration configuration scheme, and ensure the effective use of hobs under different geological conditions;

[0029] Good economy: By optimizing the specific energy of hob rock-breaking and restricting the hob load, both the rock-breaking efficiency is improved, and the replacement frequency and maintenance cost of the hob are reduced, with significant economic benefits;

[0030] Simple operation: The method of the present invention is based on clear mathematical models and experimental data, with clear operation steps and is easy to apply and promote in actual engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 It is the overall flowchart of the method for enhancing the efficiency and reducing the consumption of hob rock-breaking based on the optimal specific energy and limit load provided by the present invention.

[0033] Figure 2 It is the fitting curve of the specific energy of hob rock-breaking and operating parameters when the uniaxial compressive strength of the rock is 190 MPa.

[0034] Figure 3 It is the fitting curve of the operating parameters and the uniaxial compressive strength of the rock when the specific energy of hob rock-breaking is optimal.

[0035] Figure 4 It is the relationship curve between the penetration of hob rock-breaking and the uniaxial compressive strength of the rock when the cutter spacing is 75 mm.

[0036] Figure 5 It is the penetration configuration curve for enhancing the efficiency and reducing the consumption of hob rock-breaking. DETAILED DESCRIPTION OF THE INVENTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings:

[0038] In the following embodiments, the energy efficiency of hob rock breaking is evaluated by the specific energy of rock breaking SE, that is, the energy consumed by the hob to break a unit volume of rock. The lower the specific energy of rock breaking, the higher the energy efficiency of the hob. The unit of the specific energy of rock breaking is MJ / m3; the operating parameters of the hob are characterized by the ratio of the hob spacing to the penetration, expressed as the hob spacing / penetration or S / h, and the units of the hob spacing and penetration are both mm.

[0039] As Figure 1 shown, a method for improving the efficiency and reducing the consumption of hob rock breaking based on the optimal specific energy and the ultimate load includes the following steps:

[0040] Step S1: Obtain the operating parameters with the optimal specific energy of hob rock breaking through indoor hob rock breaking experiments:

[0041] By conducting indoor hob rock breaking experiments under different operating parameter conditions, establish the fitting relationship between the specific energy of hob rock breaking and the operating parameters using the indoor hob rock breaking experimental data; the fitting results show that for a certain rock with uniaxial compressive strength, the specific energy of hob rock breaking has a quadratic function relationship with the ratio of hob spacing to penetration that opens upward, that is, SE = a(S / h) 2 -b(S / h) + c. The abscissa of the vertex of the quadratic function is the operating parameter S / h with the optimal specific energy of hob rock breaking, that is, b / (2a);

[0042] For example, under the condition of a rock uniaxial compressive strength of 190 MPa, the fitting relationship between the specific energy of hob rock breaking and the operating parameters is as Figure 2 shown. This fitting relationship is SE = 0.105(S / h) 2 -5.0663(S / h) + 97.687, and the value of the operating parameter S / h with the optimal specific energy of hob rock breaking is 24.1;

[0043] Step S2: Establish the matching relationship between the hob operating parameters and the rock uniaxial compressive strength under the optimal specific energy:

[0044] Obtain the hob operating parameter S / h with the optimal specific energy of rock breaking under different rock uniaxial compressive strength conditions through the method of Step S1. The values of the hob operating parameter S / h with the optimal specific energy under four different rock uniaxial compressive strength conditions are shown in the following table;

[0045]

[0046] Establish the fitting relationship between the hob operating parameter S / h and the rock uniaxial compressive strength σ under the optimal specific energy as Figure 3 shown. The fitting results show that the hob operating parameters and the rock uniaxial compressive strength have a quadratic function relationship that opens downward, as shown in Equation 1:

[0047] S / h = -0.0022σ 2 +0.4692σ + 8.9577(1)

[0048] Wherein, S is the cutter spacing, unit mm; h is the penetration depth, unit mm; σ is the uniaxial compressive strength of rock, unit MPa;

[0049] Step S3: Establish the matching relationship between the hob operating parameters and the uniaxial compressive strength of rock under the ultimate load:

[0050] According to the hob rock-breaking experimental data fitting, establish the vertical load calculation formula for hob rock-breaking as shown in Equation 2,

[0051]

[0052] Wherein, F is the vertical load for hob rock-breaking, unit N, and the limit value is 250×10 3 N; T is the cutting edge width, unit mm, and the standard cutting edge width hob takes 19 mm; D is the hob diameter, unit mm, and the commonly used 19-inch hob takes 483 mm; σ is the compressive strength of rock, unit MPa;

[0053] According to Equation 2 and the above-mentioned value-taking parameters, calculate the hob operating parameters under the ultimate load; the matching relationship between the hob operating parameters and the uniaxial compressive strength of rock under the ultimate load is as shown in Equation 3;

[0054] S·h = 1.827×10 9 σ -3 (3)

[0055] Step S4: Establish an energy efficiency improvement and consumption reduction model based on the optimal specific energy of hob rock-breaking and the ultimate load:

[0056] In order to improve the hob rock-breaking efficiency, according to the relationship formula 1 between the operating parameters and the uniaxial compressive strength of rock under the optimal specific energy of hob rock-breaking, calculate the penetration depth of hob rock-breaking under different uniaxial compressive strengths of rock and different cutter spacings, which is called the optimal specific energy penetration depth; in order to reduce the abnormal loss caused by hob overload, according to the relationship formula 3 between the operating parameters and the uniaxial compressive strength of rock under the ultimate load of hob rock-breaking, calculate the penetration depth of hob rock-breaking under different uniaxial compressive strengths of rock and different cutter spacings, which is called the ultimate load penetration depth; when the cutter spacing is 75 mm, the relationship between the optimal specific energy penetration depth and the ultimate load penetration depth of hob rock-breaking and the uniaxial compressive strength of rock is as Figure 4 shown, and the optimal specific energy penetration depth and the ultimate load penetration depth of the hob under different uniaxial compressive strengths of rock and different cutter spacings are shown in the following table:

[0057]

[0058]

[0059] The rock-breaking efficiency-increasing and energy-saving method of the hob based on the optimal specific energy and the ultimate load obtains the optimal specific energy penetration of hob rock-breaking under different uniaxial compressive strengths of rocks and different cutter spacings according to the relationship between the operating parameters and the uniaxial compressive strength of rocks under the optimal specific energy of hob rock-breaking, providing a basis for reducing the specific energy of hob rock-breaking and improving the energy efficiency of hob rock-breaking; according to the relationship between the operating parameters and the uniaxial compressive strength of rocks under the ultimate load of hob rock-breaking, the ultimate load penetration of hob rock-breaking under different uniaxial compressive strengths of rocks and different cutter spacings is obtained, providing a basis for reducing the risk of abnormal damage of the hob due to overload.

[0060] When the ultimate load penetration ≥ the optimal specific energy penetration, when focusing on the rock-breaking efficiency of the hob, it is recommended to use the optimal specific energy penetration for hob rock-breaking; however, if the focus is on improving the rock-breaking efficiency of the hob and not considering the optimal specific energy of hob rock-breaking, the penetration of hob rock-breaking is selected between the optimal specific energy penetration and the ultimate load penetration.

[0061] When the ultimate load penetration < the optimal specific energy penetration, at this time, it is necessary to focus on reducing the energy consumption of the hob, and it is required that the penetration of hob rock-breaking be controlled below the ultimate load penetration.

[0062] The intersection coordinates of the optimal specific energy penetration and the ultimate load penetration under different uniaxial compressive strengths of rocks are shown in the following table, and the penetration configuration curve of the hob for efficiency-increasing and energy-saving rock-breaking is as Figure 5 shown.

[0063] Knife spacing / mm 75 80 85 90 95 100 Uniaxial compressive strength of rock / MPa 186.5 182.5 178.7 174.9 171.2 167.6 Penetration / mm 3.76 3.75 3.77 3.79 3.83 3.88

[0064] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A method for enhancing the efficiency of rock breaking and reducing energy consumption of a hob based on the optimal specific energy and ultimate load, characterized in that: It includes the following steps: Step S1: Obtain the optimal operating parameters of the cutter for rock breaking specific energy through indoor experiments on a certain uniaxial compressive strength rock with a cutter for rock breaking; Step S2: Conduct experiments on rocks with different uniaxial compressive strengths by the method of Step S1, and establish the matching relationship between the cutter operating parameters under the optimal specific energy and the uniaxial compressive strength of the rock; Step S3: Conduct indoor experiments on cutters for rock breaking on rocks with different uniaxial compressive strengths to determine the operating parameters of the cutter when it bears the ultimate load, and then establish the matching relationship between the cutter operating parameters under the ultimate load and the uniaxial compressive strength of the rock. This matching relationship is used to reflect the corresponding law between the operating parameters of the cutter and the uniaxial compressive strength of the rock when the cutter bears the ultimate load; Step S4: Combine the matching relationship between the cutter operating parameters under the optimal specific energy and the uniaxial compressive strength of the rock established in Step S2 and the matching relationship between the cutter operating parameters under the ultimate load and the uniaxial compressive strength of the rock established in Step S3. Comprehensively consider the requirements of the optimal specific energy and the ultimate load for cutter rock breaking, determine the penetration of the cutter for rock breaking, and realize the improvement of efficiency and reduction of consumption in cutter rock breaking by reasonably setting this penetration; 2. A method for enhancing the efficiency of rock breaking and reducing energy consumption of a hob based on the optimal specific energy and ultimate load according to claim 1, characterized in that: The specific content of Step S1 is to conduct indoor experiments on cutter rock breaking under different operating parameter conditions, and establish the fitting relationship between the cutter rock breaking specific energy and the operating parameters by using the indoor experiment data of cutter rock breaking; 3. A method for enhancing the efficiency and reducing the energy consumption of hob rock breaking based on the optimal specific energy and ultimate load, as claimed in claim 2, wherein: The fitting relationship between the specific energy of hob rock breaking and the operating parameters is SE = a(S / h) 2 -b(S / h) + c, where SE is the specific energy of hob rock breaking for a certain rock with uniaxial compressive strength, and the abscissa of the vertex of the quadratic function is the operating parameter S / h with the optimal specific energy of hob rock breaking, that is, b / (2a).

4. A method for enhancing the rock-breaking efficiency and reducing energy consumption of a hob based on the optimal specific energy and ultimate load according to claim 1, characterized in that: The specific content of Step S2 is to obtain the cutter operating parameter S / h when the rock breaking specific energy is optimal under the conditions of rocks with different uniaxial compressive strengths by the method of Step S1, and establish the fitting relationship between the cutter operating parameter S / h under the optimal specific energy and the uniaxial compressive strength σ of the rock; 5. A method for enhancing the efficiency and reducing the energy consumption of hob rock breaking based on the optimal specific energy and ultimate load, characterized in that: The fitting relationship between the cutter operating parameter S / h under the optimal specific energy and the uniaxial compressive strength σ of the rock is: S / h = -0.0022σ 2 + 0.4692σ + 8.9577, In the formula, S is the cutter spacing, with the unit of mm; h is the penetration, with the unit of mm; σ is the uniaxial compressive strength of the rock, with the unit of MPa; 6. A method for enhancing the efficiency of hob rock breaking and reducing energy consumption based on the optimal specific energy and ultimate load according to claim 1, characterized in that: The specific content of Step S3 is to establish the calculation formula for the vertical load of cutter rock breaking, and calculate the operating parameters of the cutter under the ultimate load according to the calculation formula for the vertical load of cutter rock breaking, so as to obtain the matching relationship between the operating parameters of the cutter under the ultimate load and the uniaxial compressive strength of the rock; 7. A method for enhancing the efficiency of hob rock breaking and reducing energy consumption based on the optimal specific energy and ultimate load according to claim 6, characterized in that: The calculation formula for the vertical load of cutter rock breaking is: In the formula, F is the vertical load of the hob for rock breaking, with the unit of N, and the limit value is taken as 250×10 3 N; T is the width of the cutting edge, with the unit of mm, and the standard cutting edge width hob takes 19 mm; D is the diameter of the hob, with the unit of mm, and the commonly used 19-inch hob takes 483 mm; σ is the uniaxial compressive strength of the rock, with the unit of MPa.

8. A method for enhancing the efficiency of hob rock breaking and reducing energy consumption based on the optimal specific energy and ultimate load according to claim 7, characterized in that: The matching relationship between the operating parameters of the cutter under the ultimate load and the uniaxial compressive strength of the rock is: S·h = 1.827×10 9 σ -3 。 9. A method for enhancing the efficiency of rock breaking and reducing energy consumption of a hob based on the optimal specific energy and ultimate load according to claim 1, characterized in that: The specific content of Step S4 is to calculate the penetration of the cutter for rock breaking under different uniaxial compressive strengths of the rock and different cutter spacing conditions according to the relationship between the operating parameters and the uniaxial compressive strength of the rock under the optimal specific energy of cutter rock breaking, which is called the penetration under the optimal specific energy; calculate the penetration of the cutter for rock breaking under different uniaxial compressive strengths of the rock and different cutter spacing conditions according to the relationship between the operating parameters and the uniaxial compressive strength of the rock under the ultimate load of cutter rock breaking, which is called the penetration under the ultimate load; When the penetration under the ultimate load ≥ the penetration under the optimal specific energy, the penetration of the cutter for rock breaking takes the penetration under the optimal specific energy to realize the efficiency improvement of the cutter for rock breaking; when the penetration under the ultimate load < the penetration under the optimal specific energy, the penetration of the cutter for rock breaking takes the penetration under the ultimate load to realize the consumption reduction of the cutter for rock breaking.

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