Calculation method of overbreak and overfill of city gate-shaped tunnel

Abstract

The application discloses a kind of calculation method of water and electricity engineering city gate hole shape tunnel overbreak rate and overfill rate in the field of water and electricity engineering.The application provides a kind of simple, reasonable, effective calculation method of city gate hole shape tunnel overbreak rate and city gate hole shape tunnel direct lining, shotcrete post-lining overfill rate based on the research of city gate hole shape tunnel overbreak, overfill and related specification, and corresponding calculation formula is given.Especially when calculating direct lining, shotcrete post-lining tunnel overfill rate, by substituting lining thickness opposite number negative value, radial overbreak value minus shotcrete thickness value into the edited overbreak rate calculation formula, engineering quantity can be greatly reduced, and efficiency can be improved.In the cost prediction and analysis stage of hydropower engineering, the method can be used to calculate the city gate hole shape tunnel overbreak rate and the direct lining, shotcrete post-lining tunnel overfill rate, solve the uncertainty problem of tunnel excavation unit price and tunnel concrete lining unit price preparation, and improve the accuracy of engineering investment preparation results.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water and electricity engineering, in particular to a calculation method of over-excavation rate and over-filling rate of city gate-shaped tunnel. BACKGROUND

[0002] Water and electricity engineering has more underground engineering, especially the popular pumped storage power station, the water delivery system and the plant are generally arranged underground, and the underground cavern group accounts for a large proportion of the engineering construction investment. During the excavation of underground cavern, over-excavation phenomenon is inevitable due to the influence of construction technology level and geological conditions. Over-excavation has different degrees of influence on the safety, quality, cost and progress of the project, mainly including the stability of surrounding rock and the increase of investment. Underground cavern generally needs concrete lining, and over-excavation will also cause over-filling of lining concrete, increase the cost of concrete lining, and have greater impact on investment. It is of great significance to reasonably predict the investment of water and electricity engineering to accurately determine the over-excavation rate and over-filling rate.

[0003] The specification file "Provisions for Engineering Quantity Calculation of Water and Electricity Engineering Design" stipulates that the engineering quantity should be calculated according to the net value of the design geometric contour size of the building or engineering, and the over-excavation and over-filling amount cannot be included in the design engineering quantity. However, over-excavation and over-filling are inevitable, and in actual processing, they are generally distributed in the comprehensive unit price. However, there is no provision for the calculation method of over-excavation rate and over-filling rate of city gate-shaped tunnel in the current regulations and specifications, causing uncertainty in the preparation of stone excavation unit price and tunnel concrete lining unit price.

[0004] The over-excavation amount in stone excavation and the over-filling amount in tunnel lining have a great influence on the comprehensive unit price, and further directly affect the project investment. Therefore, it is necessary to solve the problem of reasonable calculation of over-excavation rate and over-filling rate in the cost prediction and analysis stage. SUMMARY

[0005] In order to overcome the lack of over-excavation rate and over-filling rate calculation method in existing water and electricity engineering, which leads to the inability to estimate the project, the technical problem to be solved by the present application is to provide a calculation method of over-excavation rate and over-filling rate of city gate-shaped tunnel.

[0006] The technical scheme adopted by the present application to solve the technical problem is:

[0007] The calculation method of over-excavation rate and over-filling rate of city gate-shaped tunnel comprises the following steps:

[0008] a. Calculate the unit length city gate-shaped tunnel, the design excavation engineering quantity S of the unit length city gate-shaped tunnel 设计开挖 The over-excavation rate and over-filling rate of city gate-shaped tunnel are calculated by combining the area of the top arch, the area of the inverted triangle and the area of the rectangle, and are expressed by the design excavation bottom width a as follows:

[0009]

[0010] b, when the radial overbreak value is b, the bottom width after overbreak is:

[0011] l = a + 2b,

[0012] The top arch radius r after overbreak is the design excavation radius plus b, that is:

[0013]

[0014] The central angle of the top arch arc after overbreak is:

[0015]

[0016] The distance from the center to the rectangular vertex is:

[0017]

[0018] The straight wall height after overbreak is:

[0019]

[0020] The top arch arc area can be calculated from the central angle θ and the radius r:

[0021]

[0022] The area of the inverted triangle can be calculated from the bottom width l after overbreak and the center distance from the rectangular vertex height h1:

[0023]

[0024] The rectangular area can be calculated from the bottom width l after overbreak and the straight wall height h2 after overbreak:

[0025] S 矩形 = lh2,

[0026] The total excavation amount of the city gate hole type tunnel after overbreak can be calculated by combining the above three areas:

[0027]

[0028] The unit length city gate hole type tunnel overbreak amount is S 超挖 -S 设计开挖 , then the overbreak rate is Specifically, the design excavation bottom width a and the radial overbreak value b are expressed as follows:

[0029]

[0030] c, when the tunnel is directly lined after excavation, the cross-sectional area S 衬砌 of the concrete lining is calculated: 超挖The method is same, and in actual calculation, only the negative value b' of the opposite number of the lining thickness is replaced by b to be substituted into the formula to calculate, according to the foregoing method, the lining amount of the city gate hole type tunnel per unit length is S 设计开挖 -S 衬砌 And the overfilling amount is equal to the overexcavation amount, that is, S 超挖 -S 设计开挖 Therefore, the overfilling rate is Specifically, the designed excavation bottom width a, the radial overexcavation value b and the negative value b' of the opposite number of the concrete lining thickness are represented as follows:

[0031]

[0032] Wherein, l' = a + 2b',

[0033] If the concrete is sprayed first and then lined, the thickness of the sprayed concrete is δ, the cross-sectional area S of the tunnel after spraying the concrete is calculated as follows: 喷混凝土 And the cross-sectional area S of the tunnel after overexcavation is calculated as follows: 超挖 The method is same, and in actual calculation, only the value b'' of the radial overexcavation value b minus the thickness δ of the sprayed concrete is substituted into the formula to calculate, according to the foregoing method, the lining amount of the city gate hole type tunnel per unit length is S 设计开挖 -S 衬砌 The sprayed concrete amount of the city gate hole type tunnel per unit length is S 超挖 -S 喷混凝土 The overfilling amount is equal to the overexcavation amount minus the sprayed concrete amount, that is, S 喷混凝土 -S 设计开挖 Therefore, the overfilling rate is Specifically, the designed excavation bottom width a, the radial overexcavation value b and b'' are represented as follows:

[0034]

[0035] Wherein, l'' = a + 2b'', b'' = b - δ.

[0036] Further, the radial overexcavation value b is 0.2 m.

[0037] The present application has the beneficial effects that: through research, the present application proposes a calculation method of the overexcavation rate of the city gate hole type tunnel and the overfilling rate of the directly lined and sprayed lined tunnel in the cost prediction and analysis stage of the hydropower engineering, provides a calculation formula, the formula is simple and feasible, the calculation result is accurate, the calculation method is efficient, in the cost prediction and analysis stage of the hydropower engineering, the calculation method can be used to calculate the overexcavation rate of the city gate hole type tunnel and the overfilling rate of the directly lined and sprayed lined tunnel, solves the uncertainty problem of the tunnel excavation unit price and the tunnel concrete lining unit price preparation, and improves the accuracy of the engineering investment preparation results. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the over-excavation of the city gate-shaped tunnel of the present invention.

[0039] Figure 2 Schematic diagram of overfilling in a city gate-shaped tunnel under direct lining conditions.

[0040] Figure 3 Schematic diagram of overfilling in a city gate-shaped tunnel under the condition of shotcrete lining. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] This invention studies the over-excavation and overfilling amounts of portal-shaped tunnels, as well as relevant regulations. The regulations stipulate that only over-excavation within the design allowable range can be included in the unit price; costs exceeding the design allowable range are borne by the contractor. For horizontal tunnels, the general design allowable over-excavation value is 0.2m; therefore, the radial over-excavation value b in this application can be taken as 0.2m. Furthermore, this paper stipulates that the over-excavation rate and overfilling rate are calculated according to the common portal-shaped cross-section, i.e., the design excavation straight side wall height is the same as the design excavation bottom width a, and the design excavation top arch arc center angle is 120°. Based on these boundary conditions, a calculation method and formula for the over-excavation rate and overfilling rate of portal-shaped tunnels are proposed, mainly including the following steps:

[0043] a. such as Figure 1 As shown, the calculation is performed using a city gate-shaped tunnel of unit length. The design excavation volume S of the city gate-shaped tunnel of unit length is... 设计开挖 The area of ​​the arch's circular arc, the inverted triangle, and the rectangle is calculated using a combination of their areas, and expressed as the designed excavation bottom width 'a':

[0044]

[0045] b, such as Figure 2 As shown, when the radial overcut value is b, the bottom width after overcut is:

[0046] l = a + 2b

[0047] The radius r of the arch after over-excavation is obtained by adding the designed excavation radius b to the outward expansion, that is:

[0048]

[0049] The central angle of the arch after over-excavation is:

[0050]

[0051] The distance from the center of the circle to the vertex of the rectangle is:

[0052]

[0053] The straight wall height after over-excavation is:

[0054]

[0055] The area of the top arch circle can be calculated from the central angle θ and the radius r:

[0056]

[0057] The area of the inverted triangle can be calculated from the bottom width l after over-excavation and the height h1 of the rectangular vertex:

[0058]

[0059] The area of the rectangle can be calculated from the bottom width l after over-excavation and the straight wall height h2 after over-excavation:

[0060] S 矩形 = lh2,

[0061] The total excavation volume of the city gate hole-shaped tunnel after over-excavation can be calculated by combining the above three areas:

[0062]

[0063] The unit length city gate hole-shaped tunnel over-excavation volume is S 超挖 -S 设计开挖 The over-excavation rate is Specifically, the design excavation bottom width a and the radial over-excavation value b are expressed as follows:

[0064]

[0065] c. When the tunnel is directly lined after excavation, as shown in Figure 2 , the cross-sectional area S 衬砌 after lining with concrete is calculated in the same way as the cross-sectional area S 超挖 after over-excavation. In actual calculation, only the negative value b' of the opposite number of the lining thickness is replaced by b and substituted into the formula for calculation. According to the above method, the lining volume of the unit length city gate hole-shaped tunnel is S 设计开挖 -S 衬砌 The overfilling volume is equal to the over-excavation volume, which is S 超挖 -S 设计开挖 The overfilling rate is Specifically, the design excavation bottom width a, the radial over-excavation value b, and the negative value b' of the opposite number of the concrete lining thickness are expressed as follows:

[0066]

[0067] where l' = a + 2b',

[0068] If concrete is sprayed first and then lining is done, such as Figure 3 As shown, assuming the thickness of the sprayed concrete is δ, calculate the cross-sectional area S after spraying the concrete. 喷混凝土 The cross-sectional area S after over-excavation mentioned above 超挖 The method is the same. In actual calculation, simply substitute the radial over-excavation value b minus the shotcrete thickness δ into the formula. According to the aforementioned method, the lining volume per unit length of the city gate-type tunnel is S. 设计开挖 -S 衬砌 The amount of shotcrete per unit length of the city gate archway is S. 超挖 -S 喷混凝土 The overfill volume equals the over-excavation volume minus the shotcrete volume, which is S. 喷混凝土 -S 设计开挖 The overfill rate is Specifically, the design excavation bottom width a, radial over-excavation value b, and b″ are expressed as follows:

[0069]

[0070] Where l″=a+2b″, b" = b - 6.

[0071] The present invention will be further illustrated below through specific embodiments.

[0072] Example 1:

[0073] Several typical cross-sectional areas of tunnels with arch-shaped openings per unit length were selected for verification and compared with the reference values ​​in the "Estimated Cost Quota for Hydropower Construction Projects (2007 Edition)".

[0074] For the over-excavation rate of the city gate-shaped tunnel, the calculation method and formula given in this paper are used, and the design excavation cross-sectional area is selected as 10-150m². 2 The calculations were performed on 7 typical cross-sections, and the results were compared with the reference values ​​in Table 1.

[0075] Table 1 Verification of Over-excavation Rate Calculation Results for City Gate-Shaped Tunnels

[0076]

[0077] The over-excavation rate plus reasonable additional construction work is converted into the unit project quantity of the quota, which is the amount of rock ballast transported. As can be seen from the analysis of Table 1, for the seven typical cross-sections selected, the amount of rock ballast transported calculated by the formula is basically consistent with the corresponding quota amount of rock ballast transported, with very small deviation. This indicates that the calculation method and formula proposed in this paper for calculating the over-excavation rate of the tunnel is appropriate.

[0078] For the overfill rate of portal-shaped tunnels that are directly lined after excavation, the design excavation cross-sectional area is selected to be 10–150 m². 2 The calculation results and the comparison analysis between the 15 lining thicknesses of the 5 typical cross sections are listed in Table 2.

[0079] Table 2 Verification of Overfill Rate Calculation Results for Direct Lining of City Gate-Shaped Tunnels Table 2 Verification of Overfill Rate Calculation Results for Direct Lining of City Gate-Shaped Tunnels

[0080]

[0081]

[0082] For tunnels with direct lining, the overfill and overexcavation are equal. The overfill rate plus reasonable construction allowance is converted into the unit quantity of the quota, which is the concrete transportation volume. As shown in Table 2, for the 15 lining thicknesses across the 5 selected typical sections, the concrete transportation volume for 6 lining thicknesses deviates only slightly from the corresponding quota concrete transportation volume; the concrete transportation volume for the remaining lining thicknesses is the same as the corresponding quota concrete transportation volume. This indicates that calculating the overfill rate of the arch-shaped tunnel using the method and formula proposed in this paper is appropriate.

[0083] For the overfill rate of portal-shaped tunnels with shotcrete and anchor support and subsequent lining, a design excavation cross-sectional area of ​​10–150 m² is selected. 2 The calculation results and the comparison analysis between the 15 lining thicknesses of the 5 typical cross sections are listed in Table 3.

[0084] Table 3 Verification of Overfill Rate Calculation Results for Shotcrete Lining of City Gate-Shaped Tunnels

[0085]

[0086] For tunnels with shotcrete and anchor support followed by lining, the overfill amount equals the over-excavation amount minus the shotcrete volume. The overfill rate plus reasonable construction allowance is converted into the unit quantity of the quota, which is the lining concrete transportation volume. As shown in Table 3, for the 15 lining thicknesses across the 5 selected typical sections, except for one lining thickness where the concrete transportation volume deviates only slightly from the corresponding quota concrete transportation volume, the concrete transportation volumes for the other lining thicknesses are the same as the corresponding quota concrete transportation volumes. This indicates that calculating the overfill rate of the tunnel arch shape using the calculation method and formula proposed in this paper is appropriate.

Claims

1. A method for calculating the over-excavation rate and over-fill rate of tunnels with arch-shaped openings, characterized by: Includes the following steps: a. Calculate the design excavation volume S of a city gate-shaped tunnel per unit length. 设计开挖 The area of ​​the arch's circular arc, the inverted triangle, and the rectangle is calculated using a combination of their areas, and expressed as the designed excavation bottom width 'a': b. When the radial overcut value is b, the bottom width after overcut is: l = a + 2b The radius r of the arch after over-excavation is obtained by adding the designed excavation radius b to the outward expansion, that is: The central angle of the arch after over-excavation is: The distance from the center of the circle to the vertex of the rectangle is: The height of the straight wall after over-excavation is: The area of ​​the arch's circular arc can be calculated using the central angle θ and the radius r: The area of ​​the inverted triangle can be calculated from the base width l after over-excavation and the distance h1 from the center of the circle to the vertex of the rectangle: The area of ​​the rectangle can be calculated from the bottom width l after over-excavation and the height h2 of the straight side wall after over-excavation: S 矩形 =lh2, By combining the above three areas, the total excavation volume of the city gate-shaped tunnel after over-excavation can be calculated as follows: The over-excavation volume per unit length of the city gate-type tunnel is S 超挖 -S 设计开挖 The over-excavation rate is... Specifically, the design excavation bottom width 'a' and the radial over-excavation value 'b' are expressed as follows: c. When lining the tunnel directly after excavation, calculate the cross-sectional area S after concrete lining. 衬砌 The cross-sectional area S after over-excavation mentioned above 超挖 The method is the same. In actual calculation, simply replace b with the negative value b′ of the lining thickness and substitute it into the formula. According to the aforementioned method, the lining volume per unit length of the city gate-type tunnel is S. 设计开挖 -S 衬砌 The overfill amount equals the over-excavation amount, which is S. 超挖 -S 设计开挖 The overfill rate is Specifically, the design excavation bottom width *a*, radial over-excavation value *b*, and the negative value *b′* of the concrete lining thickness are used to represent the following: Where l′=a+2b′, If shotcrete is applied before lining, and the thickness of the shotcrete is δ, calculate the cross-sectional area S after shotcrete application. 喷混凝土 The cross-sectional area S after over-excavation mentioned above 超挖 The method is the same. In actual calculation, simply substitute the radial over-excavation value b minus the shotcrete thickness δ into the formula. According to the aforementioned method, the lining volume per unit length of the city gate-type tunnel is S. 设计开挖 -S 衬砌 The amount of shotcrete per unit length of the city gate archway is S. 超挖 -S 喷混凝土 The overfill volume equals the over-excavation volume minus the shotcrete volume, which is S. 喷混凝土 -S 设计开挖 The overfill rate is Specifically, the design excavation bottom width a, radial over-excavation value b, and b″ are expressed as follows: where l″ = a + 2b″, b″ = b - δ.

2. The method for calculating the over-excavation rate and over-fill rate of the city gate-shaped tunnel as described in claim 1, characterized in that: The radial overcut value b is 0.2m.

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