Arrangement structure and construction method for synchronizing in-well excavation and ground pre-grouting

Abstract

The invention discloses an arrangement structure and a construction method for synchronizing in-well excavation and ground pre-grouting, an unfavorable geological well section comprises n grouting sections, and the arrangement structure is characterized in that a concrete grout stop wall is arranged at an excavation tunnel face; a grouting stopping rock pillar protection layer is reserved in front of the pile number position of the grouting starting point of each grouting section from the second grouting section to the nth grouting section; according to the method, the problem that long-distance unfavorable geological structures suddenly occur in the construction process of the large-gradient long inclined shaft can be solved, and reasonable sectional grouting arrangement of the large-gradient long inclined shaft well section penetrating through the long-distance unfavorable geological structures is completed through calculation; the section length of each grouting section and the thickness of the grouting stopping wall or the reserved grouting stopping rock pillar are quantified, so that synchronous implementation of in-well excavation and ground pre-grouting of the large-gradient long inclined shaft is achieved, seamless connection of construction procedures is achieved, the construction efficiency and the construction period guarantee are greatly improved, and the construction period delay risk is reduced.

Description

Technical Field

[0001] The patent of the present invention relates to the field of underground engineering, and specifically to a layout structure and construction method for synchronously implementing excavation in a long inclined shaft with a large slope and ground pre-grouting. Background Art

[0002] According to the existing construction experience at home and abroad, the commonly used methods for general inclined shaft mud and water inrush disasters are ground pre-grouting and in-well advance grouting. As the inclined shaft develops towards large slopes and long distances, the construction conditions faced are more complicated, especially after a certain length of the inclined shaft has been constructed, when long-distance unfavorable geological structures such as faults and weak fractured zones are encountered in front of the face, if the in-well advance grouting treatment method is adopted, it is necessary to "inject and dig" in a cycle, which will cause the construction of the unfavorable geological section of the inclined shaft to take too long, thereby greatly increasing the construction period and causing delays. When the slope of the inclined shaft is large, it will cause the construction space in the inclined shaft hole to be small, and the safety of the in-well advance grouting treatment method is low. Therefore, ground pre-grouting can be considered for treatment. However, the conventional grouting method for long inclined shafts with large slopes is ground vertical group hole grouting. This grouting method has a small drilling and grouting range at one time, low grouting efficiency, and high grouting cost per meter. Therefore, the "L-type" ground pre-grouting method must be adopted for long inclined shafts with large slopes.

[0003] At present, the method of "grouting first and then excavation" is often used in inclined shaft construction, that is, ground pre-grouting is carried out before inclined shaft excavation construction. This construction sequence is only applicable to the case where the distance of the poor geological section of the inclined shaft is short. For long-distance poor geological structures, the method of "grouting first and then excavation" will lead to too long initial grouting time and thus affect the overall construction period. At the same time, due to the limitations of existing ground pre-grouting construction technology, it is impossible to achieve one-time long-distance hole grouting for long-distance poor geological structures, and segmented grouting must be used. To achieve segmented grouting, the following two problems must be solved:

[0004] 1. How to divide the grouting section

[0005] When carrying out ground pre-grouting segmented advance treatment along a long inclined shaft with a large slope, if the grouting sections are divided into too few, it will be impossible to effectively control the sudden mud and water gushing in the inclined shaft, increase the risk of construction in the shaft, and fail to achieve perfect connection with the construction in the inclined shaft, thus resulting in risks such as low construction efficiency and delays in construction period. If the grouting sections are divided into too many, although it can improve the construction period guarantee rate, it will also consume a lot of manpower and material resources, resulting in a significant increase in treatment costs.

[0006] 2. How to arrange the sequence of grouting and well construction

[0007] When carrying out segmented advance treatment of ground pre-grouting along the long inclined shaft with a large slope, if the construction method of "grouting first and then excavation" is adopted, the ground pre-grouting will take a long time, which requires sufficient grouting time before the inclined shaft construction, which will also increase the pressure of the construction period and increase the risk of construction delay. Through the above problems, it can be found that the segmented layout of ground pre-grouting and its connection with the construction in the long inclined shaft with a large slope are particularly important. Therefore, how to dynamically connect the ground pre-grouting layout with the construction process in the long inclined shaft with a large slope to achieve a perfect connection between the construction procedures is a key problem that needs to be solved in the construction process of the long inclined shaft with a large slope. However, there is a lack of relevant research in the field of underground engineering at home and abroad.

[0008] As inclined shafts develop towards greater depths and longer distances, the geological environment faced by their construction has become more complex. In particular, when long-distance adverse geological structures such as large faults and weak fractured zones are suddenly encountered during the construction process, the existing in-well advance grouting and vertical group hole grouting are difficult to meet the construction requirements, and the "L-type" ground pre-grouting treatment method must be adopted. However, due to the limitations of the existing ground pre-grouting construction technology, it is impossible to achieve one-time long-distance hole grouting for long-distance adverse geological structures, and the segmented grouting method must be adopted. How to achieve a reasonable arrangement of the "L-type" ground segmented pre-grouting and achieve a perfect connection with the well construction is a key issue that needs to be urgently solved during the construction of long inclined shafts with large slopes. Summary of the invention

[0009] The purpose of the present invention is to propose a layout structure and construction method for synchronously implementing excavation in a steep long inclined shaft and ground pre-grouting, so as to complete the reasonable segmented grouting layout of a steep long inclined shaft section crossing a long distance of unfavorable geology through calculation.

[0010] To achieve the above objectives, the technical solution of the present invention is:

[0011] A structure for synchronizing well excavation with ground pre-grouting, wherein the poor geological well section includes n grouting sections, and is characterized in that a concrete grouting-stopping wall is arranged at the excavation face, and a reserved grouting-stopping rock column protective layer is arranged before the pile number position of each grouting starting point from the second grouting section to the nth grouting section.

[0012] A construction method for realizing the synchronization of well excavation and ground pre-grouting, characterized in that the method comprises:

[0013] The bad geological section is divided into n grouting sections. The lengths of the first, second, ..., nth grouting sections are L1, L2, ..., L n The thickness of the concrete grouting wall is M, and the thickness of the reserved grouting rock column protection layer before the pile number position of each grouting section from the second grouting section to the nth grouting section is D1, D2, ..., D n-1 ;

[0014] Calculate the critical thickness of the concrete grout-stopping wall and the critical thickness of the reserved grout-stopping rock column protective layer;

[0015] The coordination and matching calculation of the inclined shaft excavation support period and the ground pre-grouting period is carried out by reserving the critical thickness of the grouting rock column protection layer;

[0016] If the coordination and matching calculation of the inclined shaft excavation and support construction period and the ground pre-grouting construction period are qualified, the large-slope long inclined shaft excavation and support and ground pre-grouting will be carried out simultaneously;

[0017] If the coordination and matching calculation between the inclined shaft excavation and support construction period and the ground pre-grouting construction period fails to meet the requirements, the grouting sections shall be re-divided or the length of the grouting sections shall be re-planned until the coordination calculation of the construction periods is met.

[0018] Furthermore, the critical thickness calculation method of the concrete stop wall is as shown in formula (1):

[0019]

[0020] Where M is the critical thickness of the concrete stop wall (m); A is the cross-sectional area of ​​the stop wall (m 2 );P k is the maximum grouting pressure of the first section of ground pre-grouting (MPa); J is the aspect ratio of the inclined shaft; [σ] is the allowable compressive strength of concrete (MPa); k is the safety factor.

[0021] Furthermore, the anti-sliding stability safety factor k0 of the concrete mortar-stopping wall should meet the requirements of formula (2),

[0022]

[0023] Where k0 is the anti-sliding stability safety factor of the concrete mortar wall; ∑P x is the fraction of the total load effect on the grouting wall along the tunnel axis (kN); ∑P z is the fraction of the total load effect on the grouting wall in the direction perpendicular to the shaft axis, with downward being positive (kN); f is the shear friction coefficient of the contact surface between concrete and surrounding rock; c is the shear cohesion of the contact surface between concrete and surrounding rock (kPa); ∑S u is the effective contact area between the concrete mortar stop wall and the surrounding rock (m 2 ).

[0024] Furthermore, the critical thickness D of the reserved grout-stopping rock column protective layer is i The calculation method is as shown in formula (3),

[0025]

[0026] Among them, Di B is the critical thickness of the protective layer of the i-th reserved grouting rock column (m); i is the cross-sectional area of ​​the protective layer of the i-th reserved grouting rock column (m 2 );P i+1 is the maximum grouting pressure of the i+1th section of ground pre-grouting (MPa); τ i is the allowable tensile strength of the protective layer of the reserved grouting rock column in the i-th section (MPa); L is the peripheral length of the inclined shaft (m); λ is the overload safety factor, n is the number of grouting sections, n≥2.

[0027] Furthermore, the critical thickness D of the reserved grout-stopping rock column protective layer is i The response can meet the following requirements,

[0028] D i ≥max{D Yi , D Ji}(i=1,2,…,n-1)(4)

[0029]

[0030] Among them, D Yi and D Ji are the thickness of the ith reserved grouting rock column calculated according to compression and shear resistance (m); σ i and τ i are the compressive strength (MPa) and tensile strength (MPa) of the i-th reserved grouting rock column; W is the width of the inclined well (m); H is the height of the inclined well (m); x is the horizontal projection distance of the inclined well section (m); ξ is the working condition coefficient of the inclined well.

[0031] Furthermore, the coordination and matching calculation of the inclined shaft excavation support period and the ground pre-grouting period includes:

[0032] Calculate the total time T for the i+1th section of ground pre-grouting during the drilling and grouting construction process i+1 ;

[0033] According to the initially planned grouting section length, the coordination of the construction period is verified by the following method:

[0034] First grouting section:

[0035] L1-v1(T2-T q )≥D1(7)

[0036] Wherein, T2 is the total time (days) spent on the second section of ground pre-grouting during the drilling and grouting construction process; T q is the time for removing the concrete stop wall (days); ν1 is the inclined shaft excavation support speed of the first grouting section (m / day); L1 is the length of the first pre-grouting section (m);

[0037] The nth grouting section:

[0038]

[0039] Among them, L i is the length of the i-th grouting section; ν i+1 Inclined shaft excavation support speed of the i+1th grouting section (m / day); T i+2 is the total time (days) spent on the drilling and grouting construction of the i+2th section of ground pre-grouting; n is the number of grouting sections n≥2;

[0040] If the calculation result does not satisfy equations (7) and (8), return to the first step to re-divide the grouting sections or re-plan the length of the grouting sections, and recalculate according to the steps until the coordination calculation of the construction period is met.

[0041] Furthermore, the synchronous construction of large-slope long inclined shaft excavation support and ground pre-grouting includes:

[0042] Concrete stop wall was constructed at the inclined shaft face, and the drilling and grouting of the first section of ground pre-grouting was started;

[0043] After the first grouting section is completed, the concrete stop wall is removed, the inclined shaft is excavated and supported, and the second section of ground pre-grouting drilling and grouting are started simultaneously. When the second grouting section is completed, the distance between the shaft face and the pile number position of the second grouting section starting point is not less than D1;

[0044] Continue to excavate and support the inclined shaft, and start the drilling and grouting of the third section of ground pre-grouting simultaneously. When the third grouting section is completed, the distance between the shaft face and the pile number position of the third grouting section starting point is not less than D2;

[0045] Similarly, the inclined shaft continues to be excavated and supported, and the drilling and grouting of the nth section of ground pre-grouting are started simultaneously. When the nth grouting section is completed, the distance between the tunnel face in the inclined shaft and the pile number position of the nth grouting section is not less than D n-1 , until the inclined shaft excavation and support is completed.

[0046] The beneficial effects of the present invention are:

[0047] The present invention can solve the problem of suddenly encountering long-distance unfavorable geological structures during the construction of a long inclined shaft with a large slope, and completes the reasonable segmented grouting arrangement of the shaft section of the long inclined shaft with a large slope that passes through the long-distance unfavorable geological structures through calculation, and quantifies the length of each grouting section and the thickness of the grouting stop wall or the reserved grouting stop rock column, thereby realizing the simultaneous implementation of the excavation in the long inclined shaft with the ground pre-grouting, achieving seamless connection of the construction procedures, greatly improving the construction efficiency and the guarantee of the construction period, and reducing the risk of construction period delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a flow chart of the layout pattern and construction method for the simultaneous implementation of in-shaft excavation and ground pre-grouting in a long inclined shaft with a large slope.

[0049] Figure 2 It is the layout type and construction schematic diagram of the simultaneous implementation of excavation in a long inclined shaft with a large slope and ground pre-grouting.

[0050] Figure 3 It is a schematic diagram of the spatial arrangement of two-stage ground pre-grouting in a long inclined shaft with a large slope according to an embodiment of the present invention.

[0051] Among them: 1-drilling rig; 2-ground pre-grouting drilling hole; 3-concrete grouting wall; 4-pre-reserved grouting rock column protective layer; 5-excavation outline of long inclined shaft with large slope; 6-grouting reinforcement boundary; 7-grouting hole. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific examples described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0053] like Figure 1 , Figure 2 As shown, this embodiment proposes a layout type and construction method for synchronous implementation of in-well excavation and ground pre-grouting in a long inclined shaft with a large slope. The present invention is aimed at a long inclined shaft with a large slope. When a long distance of unfavorable geological structure is suddenly encountered during the construction process, a reasonable grouting section layout is performed for the unfavorable geological section through calculation, and the length of each grouting section and the critical thickness of the grouting wall and the grouting rock column protective layer are clarified, so as to realize the synchronous implementation of in-well excavation and ground pre-grouting in the long inclined shaft with a large slope.

[0054] The first step is to divide the grouting sections and preliminarily determine the length of each grouting section and the thickness of the grouting wall and grouting rock column.

[0055] The grouting sections are divided into n sections. The first section is the section close to the ground. The lengths of the first, second, ..., nth sections are respectively L1, L2, ..., L n A certain overlap length is considered to be left between each two grouting sections. The overlap length is generally 20m according to the empirical value. A concrete stop wall 3 is set at the tunnel face. The thickness of the concrete stop wall 3 is M. Subsequently, a reserved stop rock column protection layer 4 is set before the pile number position of each grouting section from the second to the nth grouting section. The thicknesses are D1, D2, ..., Dn-1 .

[0056] The second step is to calculate the critical thickness of the concrete grout-stopping wall and the critical thickness of the reserved grout-stopping rock column protective layer respectively.

[0057] 1. According to the length of the first grouting section divided initially, calculate the critical thickness of the concrete stop wall at the tunnel face. The thickness calculation method is as follows:

[0058]

[0059] Where M is the critical thickness of the concrete stop wall (m); A is the cross-sectional area of ​​the stop wall (m 2 );P k is the maximum grouting pressure of the first section of ground pre-grouting (MPa); J is the aspect ratio of the inclined shaft; [σ] is the allowable compressive strength of concrete (MPa); k is the safety factor.

[0060] 2. Check the anti-sliding stability of the concrete mortar stop wall. The calculation method is as follows:

[0061]

[0062] Where k0 is the anti-sliding stability safety factor of the concrete mortar wall; ∑P x is the fraction of the total load effect on the grouting wall along the tunnel axis (kN); ∑P z is the fraction of the total load effect on the grouting wall in the direction perpendicular to the shaft axis, with downward being positive (kN); f is the shear friction coefficient of the contact surface between concrete and surrounding rock; c is the shear cohesion of the contact surface between concrete and surrounding rock (kPa); ∑S u is the effective contact area between the concrete mortar stop wall and the surrounding rock (m 2 ).

[0063] 3. According to the length of the 2nd to nth grouting sections divided initially, calculate the critical thickness D of the reserved grouting rock column protection layer i , the calculation method is as follows:

[0064]

[0065] Among them, D i B is the critical thickness of the protective layer of the i-th reserved grouting rock column (m); i is the cross-sectional area of ​​the protective layer of the i-th reserved grouting rock column (m 2 );P i+1 is the maximum grouting pressure of the i+1th section of ground pre-grouting (MPa); τ i is the allowable tensile strength of the rock mass of the protective layer of the reserved grouting rock column in the i-th section (MPa); L is the peripheral length of the inclined shaft (m); λ is the overload safety factor.

[0066] 4. Check the stability of the protective layer of the grouting rock column. The calculation method is as follows:

[0067] D i ≥max{D Yi , D Ji}(i=1,2,…,n-1)(4)

[0068]

[0069] Among them, D Yi and D Ji are the thickness of the ith reserved grouting rock column calculated according to compression and shear resistance (m); σ i and τ i are the compressive strength (MPa) and tensile strength (MPa) of the i-th reserved grouting rock column; W is the width of the inclined well (m); H is the height of the inclined well (m); x is the horizontal projection distance of the inclined well section (m); ξ is the working condition coefficient of the inclined well.

[0070] The third step is to coordinate and match the inclined shaft excavation support period and the ground pre-grouting period. When the grouting of the next grouting section is completed, the distance from the inclined shaft face to the starting point of the grouting section should be no less than the critical thickness of the reserved grouting rock column protective layer.

[0071] 1. Calculate the total time T for the drilling and grouting construction of the i+1 section of ground pre-grouting according to the actual construction period i+1 .

[0072] 2. According to the initially planned grouting section length, the coordination of the construction period is verified by the following method:

[0073] 1) The first grouting section:

[0074] L1-v1(T2-T q )≥D1(7)

[0075] Wherein, T2 is the total time (days) spent on the second section of ground pre-grouting during the drilling and grouting construction process; T q is the time for dismantling the concrete stop wall (days); v1 is the inclined shaft excavation support speed of the first grouting section (m / day); L1 is the length of the first pre-grouting section (m).

[0076] 2) The nth grouting section, (n≥2):

[0077]

[0078] Among them, L i is the length of the i-th grouting section; v i+1 Inclined shaft excavation support speed of the i+1th grouting section (m / day); Ti+2 It is the total time (days) spent on the drilling and grouting construction of the i+2 section ground pre-grouting.

[0079] 3. If the calculation result does not satisfy equations (7) and (8), return to the first step to re-divide the grouting sections or re-plan the length of the grouting sections, and recalculate according to the steps until the coordination calculation of the construction period is met.

[0080] The fourth step is the simultaneous construction of large-slope long inclined shaft excavation support and ground pre-grouting.

[0081] 1. First, construct a concrete stop wall at the inclined shaft face, and start drilling and grouting the first section of ground pre-grouting.

[0082] When there may be sudden mud and water in the front, the advance is stopped and a concrete stop wall 3 is set in front. The present invention constructs a concrete stop wall synchronously during the drilling process to prevent grouting during the grouting process. The reserved stop rock column protective layer 4 means that when the drilling and grouting of the next grouting section are completed, the distance between the face and the starting point of the next grouting section is the reserved stop rock column protective layer 4, and the reserved stop rock column protective layer 4 is the original rock mass in the forward direction of the tunnel excavation.

[0083] 2. After the first grouting section is completed, the concrete stop wall is removed, the inclined shaft is excavated and supported, and the second section of ground pre-grouting drilling and grouting are started simultaneously. When the second grouting section is completed, the distance between the shaft face and the pile number position of the second grouting section is not less than D1.

[0084] After the first grouting section is completed, the concrete stop wall is removed manually and tunnel excavation continues.

[0085] 3. Continue to excavate and support the inclined shaft, and start the drilling and grouting of the third section of ground pre-grouting simultaneously. When the third grouting section is completed, the distance between the face of the inclined shaft and the pile number position of the third grouting section starting point is not less than D2.

[0086] 4. In the following, the inclined shaft continues to be excavated and supported, and the drilling and grouting of the nth section of ground pre-grouting are started simultaneously. When the nth grouting section is completed, the distance between the face of the inclined shaft and the pile number position of the nth grouting section is not less than D n-1 . Until the inclined shaft excavation and support is completed.

[0087] In the specific embodiment of the present invention, taking an inclined shaft as an example, the specific implementation steps of the present invention are described:

[0088] Step 1: The ground pre-grouting construction is planned to be carried out in two stages for the bad geological section of pile number K0+643~K1+195. The first stage of ground pre-grouting section covers the section of pile number K0+643~K0+833, with a grouting section length of 190m; the second stage of ground pre-grouting section covers the section of pile number K0+813~K1+195, with a grouting section length of 382m. The pile numbers of the two stages overlap by 20m, that is, the pile numbers of K0+813~K0+833 overlap.

[0089] Step 2: Calculate the critical thickness of the concrete grouting wall and the critical thickness of the protective layer of the reserved grouting rock column by using equations (1) and (3) respectively, and perform stability verification.

[0090] 1) Calculation of critical thickness of concrete mortar-stopping wall and verification of anti-sliding stability

[0091] According to the actual construction conditions on site, the cross-sectional area of ​​the mortar stop wall is 57m 2 The maximum grouting pressure of the first section of ground pre-grouting is 10.08MPa, the width-to-height ratio of the tunnel is 1.09, the allowable compressive strength of concrete is 20MPa, the safety factor k is 1.4, and the critical thickness of the concrete slurry stop wall is calculated to be 5.5m.

[0092] According to the on-site engineering, the total load effect on the grouting wall during the construction stage is the grouting pressure. Therefore, the grouting pressure component is substituted into formula (2). The shear friction coefficient of the contact surface between concrete and surrounding rock is 1.2, the shear cohesion of the contact surface between concrete and surrounding rock is 7.5 MPa, and the effective contact area between the concrete grouting wall and the surrounding rock is 193.7 m 2 , after calculation, the anti-slip stability coefficient of the concrete mortar stop wall is 3.34, which is greater than 3.0. The anti-slip stability of the concrete mortar stop wall meets the requirements.

[0093] 2) Calculation of critical thickness of the protective layer of the reserved grout-stopping rock column and stability verification

[0094] According to the actual situation on site, the cross-sectional area of ​​the reserved grouting rock column protection layer is 57m 2 The maximum grouting pressure of the second section of ground pre-grouting is 15.06MPa, the tensile strength of the protective layer rock mass is 4.3MPa, the tunnel perimeter length is 27m, the overload safety factor is 1.15, and the calculated critical thickness of the reserved grouting rock column protective layer is 9.14m.

[0095] The stability check was carried out on the critical calculated thickness of the protective layer of the reserved grouting rock column. According to the actual test conditions, the ultimate compressive strength of the rock mass of the reserved grouting rock column is 27.5MPa, the width of the inclined shaft is 8.3m, and the height of the inclined shaft is 7.6m; the horizontal projection distance of the inclined shaft section is 3.1m; the working condition coefficient of the inclined shaft is taken as 1, and the thicknesses of the reserved grouting rock column calculated according to compression and shear resistance are 8.57m and 8.36m respectively. The critical thickness of the reserved grouting rock column meets the stability requirements.

[0096] Steps 3 and 4: Coordinate and match the inclined shaft excavation support period and the ground pre-grouting period

[0097] In the first phase, six boreholes (i.e., J1-1, J1-2, J1-3, J1-4, J1-5, and J1-6) were arranged. The boreholes adopted a three-level aperture and three-opening casing structure, and three drilling rigs were used for construction in two sequences. After the first phase of ground pre-grouting construction was completed, the excavation and support construction was resumed in the inclined shaft from pile number K0+580.

[0098] In the second stage, six boreholes (i.e., J2-1, J2-2, J2-3, J2-4, J2-5, and J2-6) are arranged, and the boreholes adopt a three-level aperture and three-open casing structure. Grouting is carried out through the ground pre-grouting borehole 2 and the grouting hole 7. Figure 3 The middle serial number 5 is the excavation outline of a long inclined shaft with a large slope, and the grouting reinforcement boundary 6 is the diffusion range of the grouting material on the tunnel surface.

[0099] While the first phase of construction was underway, a fourth drilling rig was deployed to sequentially construct the first and second casing sections of the six boreholes in the second phase. After the first and second casing sections were completed, one drilling rig was dismantled and three drilling rigs were used to carry out the third grouting section of the six boreholes in the second phase in two sequences.

[0100] At the beginning of the second phase of the I sequence hole compaction grouting, the inclined shaft was excavated to the vicinity of pile number K0+601.5, which was 211.5 meters away from the starting pile number K0+813 of the second phase of compaction grouting; at the beginning of the second phase of the II sequence hole compaction grouting, the inclined shaft was excavated to the vicinity of pile number K0+650, which was 163 meters away from the starting pile number K0+813 of the second phase of compaction grouting; at the completion of the second phase of the II sequence hole compaction grouting, the inclined shaft was excavated to the vicinity of pile number K0+718, which was 477 meters away from the end pile number K1+195 of the second phase of compaction grouting. During the implementation of the ground pre-grouting, the distance from the excavated face in the shaft met the safety requirements.

[0101] The above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A structure for synchronizing well excavation with ground pre-grouting, wherein the bad geological well section includes n grouting sections, characterized in that: A concrete grouting-stopping wall (3) is arranged at the excavation face, and a grouting-stopping rock column protective layer (4) is reserved before the pile number position of each grouting starting point from the second grouting section to the nth grouting section.

2. A construction method for realizing the synchronization of well excavation and ground pre-grouting as claimed in claim 1, characterized in that: The method comprises: The bad geological section is divided into n grouting sections. The lengths of the first, second, ..., nth grouting sections are L1, L2, ..., L n The thickness of the concrete grouting wall is M, and the thickness of the reserved grouting rock column protection layer before the pile number position of each grouting section from the second grouting section to the nth grouting section is D1, D2, ..., D n-1 ; Calculate the critical thickness of the concrete grout-stopping wall and the critical thickness of the reserved grout-stopping rock column protective layer; The coordination and matching calculation of the inclined shaft excavation support period and the ground pre-grouting period is carried out by reserving the critical thickness of the grouting rock column protection layer; If the coordination and matching calculation of the inclined shaft excavation and support construction period and the ground pre-grouting construction period are qualified, the large-slope long inclined shaft excavation and support and ground pre-grouting will be carried out simultaneously; If the coordination and matching calculation between the inclined shaft excavation and support construction period and the ground pre-grouting construction period fails to meet the requirements, the grouting sections shall be re-divided or the length of the grouting sections shall be re-planned until the coordination calculation of the construction periods is met.

3. A construction method for synchronous well excavation and ground pre-grouting according to claim 2, characterized in that: The critical thickness calculation method of the concrete stop wall is as shown in formula (1): Where M is the critical thickness of the concrete stop wall (m); A is the cross-sectional area of ​​the stop wall (m 2 );P k is the maximum grouting pressure of the first section of ground pre-grouting (MPa); J is the aspect ratio of the inclined shaft; [σ] is the allowable compressive strength of concrete (MPa); k is the safety factor.

4. A construction method for synchronous well excavation and ground pre-grouting according to claim 2, characterized in that: The anti-sliding stability safety factor k0 of the concrete mortar-stopping wall should meet the requirements of formula (2), Where k0 is the anti-sliding stability safety factor of the concrete mortar wall; ∑P x is the fraction of the total load effect on the grouting wall along the tunnel axis (kN); ∑P z is the fraction of the total load effect on the grouting wall in the direction perpendicular to the shaft axis, with downward being positive (kN); f is the shear friction coefficient of the contact surface between concrete and surrounding rock; c is the shear cohesion of the contact surface between concrete and surrounding rock (kPa); ∑S u is the effective contact area between the concrete mortar stop wall and the surrounding rock (m 2 ).

5. The construction method of synchronous well excavation and ground pre-grouting according to claim 2 is characterized in that: The critical thickness D of the reserved grout-stopping rock column protective layer i The calculation method is as shown in formula (3), Among them, D i B is the critical thickness of the protective layer of the i-th reserved grouting rock column (m); i is the cross-sectional area of ​​the protective layer of the i-th reserved grouting rock column (m 2 );P i+1 is the maximum grouting pressure of the i+1th section of ground pre-grouting (MPa); τ i is the allowable tensile strength of the protective layer of the reserved grouting rock column in the i-th section (MPa); L is the peripheral length of the inclined shaft (m); λ is the overload safety factor, n is the number of grouting sections, n≥2.

6. A construction method for synchronous well excavation and ground pre-grouting according to claim 5, characterized in that: The critical thickness D of the reserved grout-stopping rock column protective layer i The response can meet the following requirements, D i ≥max{D Yi ,D Ji }(i=1,2,…,n-1)(4) Among them, D Yi and D Ji are the thickness of the ith reserved grouting rock column calculated according to compression and shear resistance (m); σ i and τ i are the compressive strength (MPa) and tensile strength (MPa) of the i-th reserved grouting rock column; W is the width of the inclined well (m); H is the height of the inclined well (m); x is the horizontal projection distance of the inclined well section (m); ξ is the working condition coefficient of the inclined well.

7. A construction method for synchronous well excavation and ground pre-grouting according to claim 2, characterized in that: The coordination and matching calculation of the inclined shaft excavation support period and the ground pre-grouting period includes: Calculate the total time T for the i+1th section of ground pre-grouting during the drilling and grouting construction process i+1 ; According to the initially planned grouting section length, the coordination of the construction period is verified by the following method: The first grouting stage: L1-v1(T2-T q )≥D1(7) Wherein, T2 is the total time (days) spent on the second section of ground pre-grouting during the drilling and grouting construction process; T q is the time for removing the concrete stop wall (days); ν1 is the inclined shaft excavation support speed of the first grouting section (m / day); L1 is the length of the first pre-grouting section (m); The nth grouting section: Among them, L i is the length of the i-th grouting section; ν i+1 Inclined shaft excavation support speed of the i+1th grouting section (m / day); T i+2 is the total time (days) spent on the drilling and grouting construction of the i+2th section of ground pre-grouting; n is the number of grouting sections n≥2; If the calculation result does not satisfy equations (7) and (8), return to the first step to re-divide the grouting sections or re-plan the length of the grouting sections, and recalculate according to the steps until the coordination calculation of the construction period is met.

8. The construction method of synchronous well excavation and ground pre-grouting according to claim 2 is characterized in that: The synchronous construction of large-slope long inclined shaft excavation support and ground pre-grouting includes: Concrete stop wall was constructed at the inclined shaft face, and the drilling and grouting of the first section of ground pre-grouting was started; After the first grouting section is completed, the concrete stop wall is removed, the inclined shaft is excavated and supported, and the second section of ground pre-grouting drilling and grouting are started simultaneously. When the second grouting section is completed, the distance between the shaft face and the pile number position of the second grouting section starting point is not less than D1; Continue to excavate and support the inclined shaft, and start the drilling and grouting of the third section of ground pre-grouting simultaneously. When the third grouting section is completed, the distance between the shaft face and the pile number position of the third grouting section starting point is not less than D2; Similarly, the inclined shaft continues to be excavated and supported, and the drilling and grouting of the nth section of ground pre-grouting are started simultaneously. When the nth grouting section is completed, the distance between the tunnel face in the inclined shaft and the pile number position of the nth grouting section is not less than D n-1 , until the inclined shaft excavation and support is completed.

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